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Communicable Diseases

  1. Transmission of Communicable Diseases:
    1. Direct transmission: Contact transmission When disease is spread by direct contact with an infected person, it is called contact transmission. This may be by kissing, touching, biting or sexual intercourse. Ringworm, scabies, yaws, etc. are examples of such diseases.
    2. Indirect transmission: Vehicle (fomite) borne, vector-borne, air-borne (droplet nuclei and infected dust).
    3. Transplacental.
  2. Period of communicability
    Period of communicability or communicable period refers to the time during which an infectious agent may be transferred directly or indirectly from an infected person to a susceptible person. This period is usually equal to the maximum known incubation period for that disease.
  3. Zoonoses
    An infectious disease transmissible under natural conditions from vertebrate animals to man is called a zoonoses. There are over 150 disease common to man and animals. These include anthrax, psittacosis, liver fluke, T. solium, T. saginata, bovine TB, salmonellosis, brucellosis, scabies, plague, typhus, yellow fever and KFD.
  4. Transmission of arthropod borne disease

Direct contact

Directly transferred

Pediculosis, scabies


Diarrhoea, dysentery, typhoid, food poisoning & trachoma.



Disease agent only multiplies

Plague bacilli in rat flea Q


Cyclic change and multiplication

Malaria parasite in anopheles mosquito (AIIMS May’08)


Only cyclic change

Filarial parasite in culex mosquito, guinea worm

embryo in Cyclops. (AIIMS Nov’08)

    1. In India AIDS is most commonly caused by HIV-l subtype.
    2. HIV-l is also more Common than HIV-2 worldwide.
    3. MC mode of transmission is sexual transmission.
    4. Causes life threatening opportunistic infections, neurological disorders & unusual malignancies.
    5. Estimated number of people living with HIV/AIDS is 34-46 million.
    6. Agent:
      1. HIV or lymphadenopathy associated virus or Human T-cell lymphotropic Virus III.
      2. RNA virus with a protein capsule containing 2 short strands of RNA & enzymes.
      3. Actively replicates in T4 lymphocytes & like other retroviruses can remain in lymphoid cells in latent or activated state. It destroys the helper T cells of body.
      4. Easily inactivated or killed by – heat, B-propiolactone, ethanol, acetone & ether.
      5. Belongs to family - retroviridae.
      6. HIV: cytopathic viruses
        two types – HIV I & HIV II.
      7. Both zoonotic infection.
      8. HIV I more common than HIV II.
      9. HIV II resembles Simian immuno-deficiency virus (SIV).
      10. HIV I originated from Pan troglodytes troglodytes a species of chimpanzees.
      11. Easily killed by heat.
      12. Readily inactivated by ether, acetone, ethanol(20%) and beta - propiolactone.
      13. Relatively resistant to ionizing radiation and ultraviolet light.
  1. Reservoir of infection: cases & carriers:
    1. Sources of infection: Blood, Semen, CSF.
    2. Lower conc of HIV also found in : tears, saliva, breast milk, urine, cervical & vaginal mucus.
    3. Host factors: mainly sexually active group (mc-15-24), homosexuals, bisexuals, prostitutes, IV drug users, recipients of blood transfusion, clients of STD patients mostly affected.
  2. Mode of transmission:
    1. Sexual transmission – through vaginal, anal or oral route. For all forms of sex, risk of transmission is more where there are abrasions of skin or mucous membrane.
    2. Blood contact – transfusion of contaminated blood, whole blood cells, platelets, factors VIII & IX derived from human plasme.
    3. Materno-fetal – through placenta, during delivery, breast feeding.

Extra Edge
Prevalence of active TB in HIV patients: 60%
AIDS patients have a 10 times higher risk of developing TB

  1. Routes of Transmission & Efficiency of transmission

Routes of Transmission

Cumulative cases




.001 – 1%

Transfusion of blood & blood products



Sharing Needles & Syringes





25 – 30%

Percutaneous exposure

Others 7%


Mucocutaneous exposure


  1. High risk groups
    1. Homosexuals/MSM and bisexuals
    2. Heterosexual partners (including prostitutes)
    3. Intravenous drug abusers
    4. Transfusion recipients of blood and blood products
    5. Hemophiliacs
    6. Clients of CSWs
    7. Truck drivers
      1. IP: uncertain from few months to 10 yrs or even more
      2. Clinical manifestations:
        1. Initial infection: mostly asymptomatic, may have just mild illness like fever, sore throat, rash, but once infected they remain so for life & are highly infective during this period
          1. Window period: time period between initial infection with HIV & appearance of antibodies against it ; usually lasts from 2-12 wks, patient remains highly infectious but he will test negative on standard antibody blood test.
        2. Asymptomatic carrier state: Ab present, pt infectious, but no overt signs of disease except PGL.
        3. ARC: pt is ill due to damage of immune system but without opportunistic infections or AIDS related cancers. Exhibit one or more of the following signs:
          1. Unexplained diarrhoea >1 month
          2. Fatigue, malaise, fever, night sweat
          3. Loss of > 10% body weight
          4. PGL & oral thrush
Patient with 2 or > of these features with reduced T4 helper cell count is said to have ARC
  • AIDS ( End stage HIV infection): a number of opportunistic infections & cancers tend to occur. Death is usually due to untreatable infections & reduction of CD4 count.
  1. Diagnosis:
    1. WHO case definition for AIDS surveillance
      1. Major
        1. Weight loss >10% of body weight
        2. Chronic diarrhoea for > 1 month
        3. Prolonged fever for >1month
      2. Minor
        1. persistent cough for >1 month
        2. Generalized pruritic dermatitis
        3. H/O herpes zoster
        4. oropharyngeal candidiasis
        5. Chronic progressive or dissemibated herpes simplex inf.
        6. Generalized lymphadenopathy
        7. Viral load
    2. Expanded WHO case definition for AIDS surveillance: If test for HIV Ab is positive & one or > of the following conditions are present in case of an adult or adolescent.
      1. Lab Diagnosis:
        1. ELISA: 99.9% sensitive
        2. Western blot : confirmatory
        3. Other confirmatory tests: Nucleic acid based tests – RT-PCR test & Quantiplex branched DNA test
        4. Complete blood count
        5. Absolute CD4 count
        6. CD4 lymphocyte percentage
        7. HIV viral load tests
  2. Control of AIDS - 4 basic approaches
    1. Prevention
      1. By education for life saving choices, avoid use of shared razors, tooth brush, use of  sterilized needle & syringes.
      2. By refraining from donating blood if people come under high risk group.
      3. All blood should be screened for HIV 1 & 2.
      4. Targeted Intervention is being currently given to the following high risk groups of HIV:
        1. CSW Interventions 209
        2. Truckers Interventions 190
        3. Migrant Workers Interventions 249
        4. IDU Interventions 74
        5. Street Children Interventions 26
        6. MSM Interventions 25
        7. Prison Inmates Interventions 56
        8. Others 56
    2. Antiretroviral T/t: zidovudine, saquinavir, nevirapine
      1. WHO Recommendation for initiating ART in adults and adolescents (2006).

WHO Clinical Stage

CD4 testing not available

CD4 testing available


Do not start ART

Start ART if CD4 <200/ cmm


Do not start ART

Start ART if CD4 <200/ cmm


Start ART

Consider starting ART if CD4 < 350/cmm, starting before it drops to <200/cmm. Recommended for all HIV + pregnant women if CD4<350/cmm


Start ART

Start ART irrespective of CD4 count

  1. WHO Recommendation for initiating ART in Infants and Children (2006)


Criteria to start ART in infants & children

Infants <12 m

12m through 35m

36m through 59m

5 yrs & over

% CD4





Absolute CD4

<750 cmm

<350 cmm

As in adults

Post exposure prophylaxis: 
4 wks of T/t with zidovudine after accidental exposure to HIV by needle prick.

  1. Specific prophylaxis
  2. Primary health care
  1. Chickenpox (varicella zoster)
    1. Chickenpox is a highly communicable disease caused by the varicella virus, a member of the herpes virus family. In temperate climates, chickenpox occurs most frequently in winter and early spring.
    2. Incubation period of Chicken Pox is 7-21 days and commonly it is 14-16 days.
    3. It can affect people of all ages but most commonly children below 10 years are affected as they do not have protective antibodies.
    4. Chickenpox is transmitted to others by direct person-to-person contact, by droplet or airborne spread of discharges from an infected person's nose and throat or indirectly by contact with articles freshly soiled by discharges from the infected person's lesions.
    5. The scabs themselves are not considered infectious. Crusts of chickenpox are also not infective.
    6. The rash in chickenpox has a centripetal distribution – first appearing on the trunk and then spreading towards the periphery. The palm and soles are not affected. The rash is seen mostly on the flexor surfaces and appears on the very first day and thereafter in crops, evolving very rapidly. The lesions are superficial, unilocular  and are surrounded by a red areola. They are small, elliptical and mostly discrete with no umbilication.
  1. Complications associated with chickenpox Newborn children (less than one month old) whose mothers are not immune and patients with leukemia may suffer severe, prolonged or fatal chickenpox. Immunocompromised patients, including those on immunosuppressive drugs, may have an increased risk of developing a severe form of chickenpox or shingles. Reye’s Syndrome has been a potentially serious complication associated with clinical chickenpox involving those children who have been treated with aspirin. Aspirin or aspirin-containing products should never be given to a child with chickenpox.
  2. Vaccine for chickenpox A vaccine to protect children against chickenpox was first licensed in March 1995. It has been recommended for persons over 12 months of age. To protect high-risk newborns and immunocompromised patients from exposure, a shot of varicella zoster immune globulin (VZIG) is effective in modifying or preventing disease if given within 96 hours after exposure to a case of chickenpox. Older children and adults who have previously had chickenpox do not need to be vaccinated.
  3. Treatment for chickenpox: In 1992, acyclovir was approved by the U.S. Food and Drug Administration for treatment of chickenpox in healthy children. However, because chickenpox tends to be mild in healthy children, most physicians do not believe that it is necessary to prescribe acyclovir.
  1. Measles
    1. Measles virus is a RNA paramyxovirus. The virus can not survive outside the human body for any length of time.
    2. > 80% SAR among susceptible.
    3. The only source of infection is a case of measles. Carriers are not known to occur.
    4. Most infection are clinical (sub-clinical infection not seen).
    5. Immunity develops 11-12 day after vaccination & persist throughout life.
    6. The incubation period of measles ranges from 8–16 days with an average incubation period of 10 days.
    7. Common life-threatening complications of measles are broncho-pneumonia and diarrhea. Encephalitis can also occur rarely.
    8. Measles is most infectious 4 days before to 5 days after the rash appears.
    9. An eruptive rash appears in measles as dark red macules or maculopapular granules, first evident behind the ears and at the junction of the scalp and forehead and then spreading over the face, trunk and limbs, very rapidly. The rash lasts for 4-6 days and disappears in the same order in which it appeared. It dries off leaving a brawny discoloration of the skin.
Extra Edge:
TYPHOID “Rose spots,” appear as small, pale red, blanching, slightly raised macules and are occasionally seen on the chest and abdomen during the first week. They can evolve into nonblanching small hemorrhages
 MEASLES The characteristic erythematous, non pruritic, maculopapular rash of measles begins at the hairline and behind the ears, spreads down the trunk and limbs to include the palms and soles, and often becomes confluent.
 SMALLPOX An eruption that passes through the successive stages of macules, papules, vesicles, pustules, and crusts. Only one stage of rash may be seen at one time.
CHICKENPOX The skin lesions include maculopapule, vesicles, and scabs in various stages of evolution.
Rash is pleomorphic, i.e. different stages of rash are seen at one given time, because rash appears in successive crops.
  1. Influenza A (H1N1)
    Influenza A (H1N1) is an influenza virus, which has been reported as a cause of illness and death in people. It was earlier known as Swine Flu. Originating in Mexico in April 2009, the virus has since spread to many countries worldwide.Early laboratory testing showed that many genes in this virus were similar to those found in pigs of North America, which is why the illness was originally called Swine Flu. Later on, further tests proved that this virus has gene segments from the swine, avian and human flu virus genes. This led scientists to discard the previous name and rename the virus the 'Influenza-A (H1N1) Virus'.
    1. Symptoms of Influenza A (H1N1)
      The symptoms of Influenza A (H1N1) are similar to the symptoms of regular seasonal flu.
      People who have this illness may experience fever, cough, sore throat, body aches, headache, chills and fatigue. Some patients have also reported diarrhoea and vomiting.
      The flu virus is thought to spread from person to person through droplets that come out of an infected person's nose or mouth when he/she sneezes or coughs. Pigs have nothing to do with this disease. Pork products are absolutely safe if properly cooked and culling of pigs is not needed.
      IP: Commonly 3-7 days, may extend upto 10 days.
    2. Commons Precautions
      Here are some precautions to prevent contraction of the virus-
      1. Cover your nose and mouth with a tissue when you cough or sneeze. Discard the tissue after use.
      2. Wash your hands thoroughly after you cough or sneeze.
      3. Avoid touching your eyes, nose or mouth as germs may spread this way.
      4. Stay away from close contact with people having respiratory illnesses.
      5. If one displays influenza like symptoms, one must limit contact with others by staying at home. However, in case of respiratory distress, one should visit a nearby hospital without delay.
      6. Take care of your health. Get plenty of sleep, exercise regularly, manage stress, drink plenty of liquids and eat wholesome food.
      7. The Government has also created a strategy to detect Influenza A (H1N1) cases among passengers arriving from affected countries either by air, land or sea and quarantine them. A standard process for screening, testing and treatment will be used across the country. If you have travelled from any of the affected countries in the past 10 days and display the symptoms of Influenza A (H1N1), then kindly visit a nearby hospital.
      8. Treatment: DOC is Oseltamivir.
      9. Chemoprophylaxis: Oseltamivirxz.
  2. Rubella
    A baby born to a mother with rubell may may be born with congenital defects like deafness, microcephaly, microphthalmia, PDA, septal defects and other malformations, which are called the Congenital Rubella Syndromme, if the mother is infected during pregnancy. The frequency of congenital defects is 20-25% if infection occurs in 1st trimester and less after that.
  3. Diphtheria
    Diphtheria is spread through direct droplet/ direct air-borne routes and indirectly through inhalation of contaminated dust by dried particles of the diphtheria membrane. It can also be spread through contaminated milk, fomites, convalescent or healthy carriers, cross infection in wards and infection of wounds or cuts in skin or mucous membrane, including conjunctiva.
    1. Schick test
      1. The Schick test was done to identify individuals who are susceptible to diphtheria and those who are allergic to the toxoid use in the vaccine. Schick test.
      2. Injecting i/d into skin of forearm 0.2 ml of Schick test toxin, while into opposite arm, is injected as a control- same amt. of antitoxin, inactivated (better control – fluid toxoid vaccine preparation).
      3. Negative Reaction- no reaction of any kind on either arm- immune to diphtheria->0.03 units of antitoxin/ml.
      4. Positive reaction- in test arm-circumscribed red flush- 10-50 mm dia- generally appears within 24-36 hrs – max. 4-7 day, slowly fades, desquamates; control arm shows no reaction- person is susceptible.
      5. Pseudo positive reaction- a red flush equally on both arms, but less circumscribed than the true positive reaction, reaction fades very quickly and disappears by 4th day – allergic type of reaction- Schick test negative.
      6. Combined reaction- control arm shows pseudo negative reaction , test arm is true positive. The person is susceptible to diptheria.
      7. A person who is proved to be susceptible but allergic- vaccination with caution.



i   Negative

Not Susceptible & No Hypersensitivity

(H.S.) & Immune to dipth.

ii   Positive

No H.S.& susceptible to dipth.

iii Psuedo (+)

H.S. Present Not susceptible

iv. Combined

HS Present, Susceptible Dipth.

  1. Tuberculosis
    1. Normal reactions that occur after giving BCG vaccine
      The weal raised immediately after giving the BCG vaccine disappears within a few hours. Nothing happens over the next two weeks. Redness and induration at the site are seen in the third week. A papule then develops reaching its maximum size in the 4th week. The papule cracks, discharges pus and is gradually changed into a crust during the 5th – 6th week. The scab falls off during the 7th – 8th week leaving a small oozing ulcer which heals and leaves a scar about 5 mm in diameter. These reactions are often more marked in positive reactors.
    2. Tuberculin test
      The tuberculin test is performed to screen individuals who are already infected and those who are highly susceptible to the disease. Tuberculin containing PPD (purified protein derivative) prepared from the RT strain along with Tween 80 is injected intradermally. The injection is given on the anterior side of the forearm and the result is read after 48 – 72 hours. The induration is measured and any induration greater than 10 mm is taken as positive. Strong reactors (more than 20 mm induration) have more chance of developing active TB. Similarly weak reactors (< 5 mm) also have a higher chance of infection. In countries where BCG vaccine is given at birth, tuberculin testing loses its value.
    3. Prevalence rate of tuberculosis infection in India
      The prevalence of TB infection is the percentage of individuals in the community showing positive reaction to tuberculin test. Its usefulness has decreased in recent years due to widespread BCG immunization. A third of the Indian population is infected transmission of infection in a community. The prevalence rate of TB disease is 4 per 1000 population while the incidence rate of disease is 1 per 1000 population.
    4. Case of tuberculosis
      A case of TB is an individual who is sputum positive and is therefore capable of transmitting infection. While a suspect of TB is a person who is sputum negative but has radiological evidence of Tubercular shadows in the lungs. Therefore, a case is infectious while a ‘suspect’ is not infectious.
  2. Acute respiratory infections
    1. Danger signals signifying severe disease in Acute Respiratory Infections
      1. Child stops proper feeding.
      2. Child too sleepy or difficult to wake up.
      3. Stridor even when the child is calm.
      4. Wheezing.
      5. Convulsions.
      6. Severe malnutrition.
      7. A very young infant who has fever or is cold to touch.

  1. Meningococcal Meningitis
    1. Etiology
      1. Neisseria meningitidis, a gram-negative aerobic diplococcus
      2. 13 serotypes although only five serotypes, A, B, C, Y and W135, are clinically important
      3. Serotypes A, B and C most common causes of illness worldwide, with serotypes B and C predominant in Europe, and A and C predominant throughout Africa and Asia.
      4. In recent years increasing emergence of serotype W135 in Africa and the Middle East.
      5. Common inhabitant of the mucosal membranes of nose and throat.
      6. Upto 5-10% of the population may be asymptomatic carriers.
      7. Approximately 500 million people worldwide are carriers of the bacterium in their nasopharynx.
    2. Transmission
      1. By direct contact, including respiratory droplets.
      2. Predisposing factors: waning immunity in population against a strain, active or passive inhalation tobacco smoking, upper viral respiratory tract infections, drought seasons, and overcrowding. These factors explain the frequent occurrence of outbreaks
    3. Incubation Period
      1. 2 to 10 days, most often three to four days
    4. Clinical Features
      1. Spectrum of disease ranges from occult bacteremia to fulminant sepsis resulting in death in only a few hours.
      2. Meningococcemia or meningitis (with or without meningococcemia).
      3. Febrile, with headache, vomiting, malaise, and often myalgia. A hemorrhagic rash- frequently evolving into purpura and shock.
      4. Meningeal infection, resulting from hematogenous seeding, occurs in about 50% of patients.
      5. Clinical S/S similar to other causes of acute bacterial meningitis with abrupt onset of headache, fever, neck stiffness, often accompanied by nausea, vomiting, photophobia and altered mental status. 
        • Despite medical care, mortality rates remain at 9-40%, with 11-19% of survivors with serious sequelae such as hearing loss, neurologic disability, or loss of limb.
    5. Children >1 year and adults
      1. Neck stiffness
      2. Headache
      3. Nausea and vomiting
      4. Neck and/or back pain
      5. Fever and chills
      6. Increased sensitivity to light
      7. Irritability, confusion
    6. Infants
      1. Refusing feeds
      2. Increased irritability
      3. Sleeping all the time
      4. Fever
      5. Bulging fontanelle
      6. Inconsolable crying
      7. Epileptic fits (seizures)
    7. Diagnosis
      1. Lumbar puncture
      2. CSF smear
      3. CSF culture
      4. CSF biochemistry
      5. PCR assays for bacterial DNA- widely used in the UK
      6. Skull X-ray, sinuses X-ray and chest X-ray
      7. Head CT scan for abscess or deep swelling
      8. (Antigen tests of urine or serum are unreliable)
    8. Management
      1. Always view as medical emergency
      2. Admission to hospital/health centre
      3. Initial assessment of ABC
      4. Management of shock
      5. Monitor for metabolic abnormalities and acute renal failure
      6. Cultures of blood, CSF and skin lesions ideally prior to antibiotics
      7. Treatment: Penicillin G i.v. 250,000 units/kg/day (maximum 12 million units/day) divided every 4-6 hours. Cefotaxime, ceftriaxone, and ampicillin acceptable alternatives. For patients with anaphylactic penicillin allergy-chloramphenicol. Five to seven days of  therapy. Use of steroids remains controversial
    9. ChemoprophylaxisRecommended for household contacts of an index case, and persons who have had significant contact with oral secretions of the index case, including healthcare workers.
      1. Useful only in the endemic situation; not an effective mean of interrupting transmission during an epidemic.
      2. DOC: Rifampicin. 600mg BD X 2 days.
      3. Others: Minocycline, Spiramycin, Ciprofloxacin, Ceftriaxone.
      4. Ciprofloxacin as a single oral dose for adults is also an option.
      5. Some experts recommend a single dose of azithromycin for adults.
      6. Rifampicin C/I in pregnant women. For them a single i/m dose of ceftriaxone.
    10. Immunoprophylaxis
      A mass immunization campaign that reaches atleast 80% of the entire population, needed to halt an epidemic Vaccination is recommended for high-risk groups Immunization advised by WHO for travelers to the “meningitis belt” and the areas affected by outbreaks Meningococcal vaccination not compulsory for entry into any country, except Saudi Arabia, for pilgrims to Mecca for the Hajj. In the UK, universal vaccination with meningococcal conjugate C vaccine.
      1. Meningococcal Vaccines
        1. Polysaccharide vaccines
        2. Monovalent (group A or C)
        3. Bivalent (groups A & C)
    11. Tetravalent (groups A,C,W135 & Y)
      1. Purified, heat-stable, lyophilized capsular polysaccharides.
      2. Each dose has 50mcg of each individual polysaccharide.
      3. Short-term efficacy 85-100% in age 2 and above.
      4. Protective Ab response in 10-14 days.
      5. No difference in safety & immunogenicity b/w Bi and Tetra-valent.
    12. Conjugate vaccines
      1. Group C meningococcal conjugate (MCC) vaccine.
      2. 3 MCC vaccines currently licensed internationally.
      3. In 2, a non-toxic Diphtheria toxin form used.
      4. In  the other, Tetanus toxoid is the carrier protein.
      5. Became part of the national immunization programme of UK since 1999.
      6. Serogroup C causes 35% of meningococcal disease in the UK.
      7. Infants vaccinated at 2,3 and 4 months; children & young adults offered catch-up immunization as a  single dose.
      8. Has used immunogenicity rather than efficacy data for licensure.
      9. Initially age groups with highest incidence (under 5) and the greatest burden of mortality (15–17y)  targeted. Plan to vaccinate all individuals under 25 years of age.
      10. MCC expected to provide high levels of protection for at least 10 years 2. Group A meningococcal conjugate (menA) vaccine.
      11. Being developed as part of the MVP project.
      12. Expected to be available by 2008-9.
  2. Typhoid
    1. Incubation period of Typhoid is 10 – 14 days, but it can range from 4 – 21 days.
    2. Convalescent carrier A convalescent carrier is one who sheds infective micro-organisms during the period of convalescence. In typhoid this is for a period of 1-2 weeks after the temperature comes down.
    3. Permanent carrier A permanent carrier is one who continues to shed organisms forever after the disease has been cured. This is seen in typhoid where the gall bladder and kidneys are involved and bacilli are passed for a long time with interspersed periods of remission. 2.5% of typhoid cases develop into permanent carriers.
    4. Period of isolation: Till 3 negative stool or urine test on three different occasions. (AIIMS May’09).
  3. Polio (AIIMS May’08)
    1. Agent: Polio virus type 1, 2, 3.
    2. P1: MC cause of epidemics & paralytic polio.
    3. P2: Most antigenic & therefore most easy to control.
    4. P3: MCC of VAPP, responsible for maximum cases in India.
    5. Reservoir: Humans only (no chronic carrier or animal host)
    6. Incubation period is 7-14 days with an overall range of 3-35 days.
    7. The prevalence of polio in the community is assessed by conducting lameness surveys in the community among children aged 0-10 years. Lameness in children aged 0-4 years is most indicative of the current level of the problem.
    8. Vaccines for polio:- There are two types of vaccines available for prevention against polio – One is a killed vaccine and is injected (Salk vaccine) and the other is a live vaccine which is given orally (Sabin vaccine).
  1. Clinical Feature
    1. Inapparent(sub clinical) infection Commonest 95%
    2. Abortive or minor illness – 4 - 8 %
    3. = Virus isolation, Ab titer
    4. Non paralytic polio (1%) Aseptic meningitis
    5. Paralytic polio (<1%)
    6. No sensory loss
    7. Asymmetrical Flaccid paralysis
    8. Descending
    9. Cranial nerve involvement in bulbospinal form of polio
  2. Case Definition: In the global polio eradication initiative, acute flaccid paralysis is defined as:
    1. Any case of AFP in a child aged <15 yrs, or any case of paralytic illness in a person of any age when polio is suspected.
    2. Acute: rapid progression of paralysis from onset to maximum paralysis.
    3. Flaccid: loss of muscle tone, “floppy” as opposed to spastic or rigid.
    4. Paralysis: Weakness, loss of voluntary movement.
  3. AFP Case Investigation:
    1. Every AFP case to be investigated within 48 hrs of reporting.
    2. Stool sample collection: From every AFP case, 2 stool samples, 24 – 48 hrs apart, within 14 days of onset of paralysis (max 8weeks), each sample 8 gms, clean, dry, screw capped container which is transported to the WHO accredited lab in “reverse cold chain”.
  1. Leprosy (AIIMS Nov’08)
    1. Lepromin Test detects cell mediated immunity. It simply measures the individual susceptibility or resistance. It does not indicate past or present infection. Lepromin positivity is associated with resistance to leprosy infection. After intradermal injection of 0.1 ml of lepromin antigen, two types of reactions can be seen. These are referred to as the early (Fernandez), which is read at 48 hours and the late (Mitsuda) reaction, which is read at 21 days. The early reaction comprises of redness and induration and is regarded as positive if the area of redness is greater than 10 mm at 48 hours. The late reaction consists of a papule or nodule, which is first measured after 2 weeks, and then at weekly intervals.
    2. Rationale for MDT in Leprosy
      1. MDT in leprosy is very useful because of the following reasons:
        1. To interrupt transmission of the infection in the community as rapidly as possible using a combination of bactericidal drugs.
        2. It provides an opportunity for cure
        3. It helps to prevent drug resistance.
        4. A shorter course of therapy ensures a better compliance
        5. There is reduced work load on the health-care delivery system.
    3. Bacteriological index
      This index denotes change in the number of leprosy bacilli present in the tissues. Smears are made from at least 7 sites, including a nasal smear, both earlobes and 4 skin lesions. Each smear is graded separately. If there are no bacilli, a score of ‘0’ is given while if bacilli are found in some fields (mean < 1 bacilli per field), it is scored as ‘1’; If bacilli are found in all fields it is scored as ‘2’ and if many bacilli are found in all fields it is scored as ‘3’. All scores of all smears are added and a mean calculated. If the index is < 2, it is paucibacillary leprosy and if it is > 2 it is classified as multibacillary leprosy.
    4. Morphological index
      A. This index is the percentage of solid rods among 200 organisms counted in a smear stained for demonstrating M. leprae. Solid rods represent the viable bacilli. This index changes more rapidly than the bacteriological Index. If it shows a rise after an initial decline, it could indicate either inadequate drug intake or development of drug resistance.
    5. Leprosy control units are established in endemic zones with a prevalence rate of 5 per 1000 and above and cover a rural population of 4-5 lakhs. There is a central leprosy clinic at the headquarters.
    6. SET centers under NLEP stands for survey, education and training and these are the main functions of these centers. These are established in endemic zones where prevalence rate is < 5 per 1000.
  2. STDs
    1. A. STDs are diseases in which sex plays an important part in transmission. They include the five classical diseases–syphilis, gonorrhea, chancroid, LGV and granuloma inguinale and additional conditions like non gonococcal urtheritis, herpes progenitalis, genital warts, trichomoniasis and moniliasis. In addition, some diseases where sexual transmission is possible but not epidemiologically important are also considered as STDs. These include genital scabies, hepatitis B, genital pediculosis and genital molluscum contagisum.

2. Classification of sexually transmitted disease agents

Bacterial agents - Neisseria gonorrhoeae; Chlamydia trachomatis; Treponema pallidum; Haemophilus ducreyi; Mycoplasma hominis; Ureaplasma urealyticum; Calymmatobacterium granulomatis; Shigella spp.; Campylobacter spp.; Group B streptococcus; Bacterial vaginosis -associated organisms

Viral agents - Human (alpha) herpesvirus 1 or 2 (herpes simplex virus) Human (beta) herpesvirus 5 (formerly cytomegalovirus) Hepatitis virus B; Human papilloma viruses; Molluscum contagiosum virus; Human immunodeficiency virus

Protozoal agents - Entamoeba histolytica; Giardia lamblia; Trichomonas vaginalis

Fungal agents - Candida albicans

Ectoparasites - Phthirus pubis; Sarcoptes scabiei


 3. Important sexually transmitted pathogens and the diseases caused by them


Disease or syndrome

Neisseria gonorrhoea

Gonorrhoea urethritis cervicitis epididymitis, salpingitis, PID, neonatal conjunctivitis

Treponema pallidum


Haemophilus ducreyi


Chlamydia trachomatis

LGV, urethritis, cervicitis, proctitis, epididymitis, infant pneumonia, Reiter's syndrome, PID, neonatal conjunctivitis

Calymmatobacterium granulomatis

Donovanosis (granuloma inguinale)

Herpes simplex virus

Genital herpes

Hepatitis B virus

Acute and chronic hepatitis

Human papillomaviruses

Genital and anal warts

Human immuno deficiency virus (HIV)


Molluscum contagiosum

Genital molluscum contagiosum

Candida albicans


Trichomonas vaginalis


  1. Syndromic Approach: 5 syndromes based on the chief presenting complain
    1. Urethral discharge/Burning micturition ( gonococcal or chlamydial)
    2. Vaginal discharge: Cervicitis ( gonococcal or chlamydial) or vaginitis (trichomoniasis, Candiasis or bacterial vaginosis)
    3. Genital ulcer: Syphilis, chancroid, LGV, Granuloma inguinale or herpes virus infection (multiple painful blisters)
    4. Inguinal swelling (bubo): usually due to LGV
    5. Lower abdominal pain: PID
  2. Management of Urethral discharge/Burning micturition
    1. Treat for both Chlamydial & gonococcal infections.
    2. Gonorrhoea: Cefixime 400 mg single dose.
    3. Chlamydia: Azithromycin 1g single dose or Doxycycline 100mg BD X 7days or Erythromycin 500mg QID X 7 days.
    4. Suspect trichomoniasis if discharge persists even after above treatment & give Secnidazole 2g single dose & treat the partner also.
  3. Management of Genital ulcer
    1. Vesicles/multiple painful ulcers (Herpes): Acyclovir 400mg TDS X 7days
    2. Syphilis: Inj. Benzathine penicillin, 2.4 million units i/m in 2 equal divided doses, one in each buttock ATD
    3. Chancroid: Azithromycin 1g single dose
  4. Management of Vaginal Discharge
    1. Could be due to cervicitis due to Gonorrhoea or Chlamydia: T/t same as males
    2. Could be due to vaginitis:
    3. Bacterial: Secnidazole 2g single dose
    4. Candiasis: Fluconazole150mg single dose or Clotrimazole 500 mg vaginal pessary
  5. Management of Lower Abdominal pain
    1. PID: Infection of the genital tract above the cervix
    2. May be caused by a wide variety of organisms
    3. Infertility is a frequent complication
    4. T/t: Cefixime 400 mgX 7 days +
      Metrinidazole 400mg BD X 14 days+
      Brufen & Rantac+
      IUD removal if present+
      A urine pregnancy test to rule out ectopic pregnancy.
  6. Contact tracing is for tracing of Sexual partners of STDs cases (also called conjugal partners) must be located, examined and treated. This helps in arresting the transmission of disease. This process of identifying and following up the contacts is called contact tracing.
  7. Partner notification All cases of STDs are asked to name all their sexual partners from whom they could have contacted the disease or to whom they could have transmitted the disease. This process of  identifying the sexual partners is called partner notification.
  8. Incubation period of gonorrhea is 2-7 days.It is primarily spread by sexual intercourse. The chance of contracting gonorrhea after a single exposure is 20-35% for men and probably double for women.
  1. Plague
    1. Incubation period of plague  is 3-4 days.
    2. Pneumonic plague is infectious and is responsible for man-to-man spread. Other forms of plague are only transmitted through bite of rat flea which is infective for a few months under suitable conditions. Man-to-man transmission can.

1.  Stages of plague

Bubonic plague

Pneumonic plague


IP. 2 - 7 days

I.P 1-3 days

I.P. 2-7days

MC type

Suppuration is

favourable sign

man to man spread present

Highly infectious via droplet

DOC for chemoprophylaxis is tetracycline & for treatment is streptomycin

Steps be taken to control an epidemic of plague:-

  1. The following steps should be followed for control of plague in man:
    1. Notification: Continuous surveillance of human and rat plague and its immediate notification.
    2. Isolation in cases of pneumonic plague.
    3. Suspected contacts should be quarantined for 6 days. This also applies to vessels and plane coming from plague infected areas.
    4. All unusual rat falls should be investigated and dead rats should be dissected for microscopic evidence of plague.
    5. Prompt treatment with antibiotics like streptomycin, chloramphenicol, etc. should be instituted.
    6. Chemoprophylaxis should be instituted for contacts.
    7. Adequate disinfection measures should be instituted. Safe disposal of sputum and proper boiling of patient’s clothes should be undertaken.
    8. Insecticidal spraying of affected areas.
    9. Rat burrows should be treated with DDT.
    10. Mass inoculation with plague vaccine.
    11. Health education measures.

Extra edge
Typhoid is regarded as                   - Index of general sanitation of country
Tuberculosis is called                     - Barometer of social welfare
Black death term was given to       - Plague

  1. Rabies
    1. Causative organism for rabies is Lyssavirus type 1, a neurotropic virus belonging to the family of Rhabdoviruses. The incubation period is usually between 2-8 weeks.
    2. When a patient comes with a history of a dog bite by an unknown dog
      After being bitten by any unknown animal the following steps should be undertaken:
      1. Exact wound should be carefully examined. It should be seen whether there are true bite marks on the skin or whether the clothes prevented a bite. If the bite has not penetrated through the clothes, vaccine is not necessary.
      2. Local treatment: Should be washed thoroughly with water and 20% soap solution. It should then be washed with savlon.
      3. Topical application and infiltration of 5 ml hyperimmune antirabies serum or gamma globulin should be done.
      4. Wounds should not be sutured. If sutures are essential, loose sutures should be applied.
      5. Anti-tetanus serum or a booster dose of TT should be given if the person gives a history of previous immunization.
      6. Antirabies vaccine should be instituted.

Early symptoms include irritability, headache, fever and sometimes itching or pain at the site of exposure. Within days, the disease progresses to paralysis, spasms of the throat muscles, convulsions, delirium and death.

  1. Exposure category and immunization:

Table 1 - Guidelines for post - exposure treatment


Type of contact with a suspect or confirmed rabid domestic or wilda animal or animal unavailable for observation



Touching or feeding of animals, Licks on intact skin

None, if reliable case history is available


Nibbling of uncovered skin; Minor scratches or abrasions without bleeding; Licks on broken skin

Administer vaccine immediatelyb. Stop treatment if animal remains healthy throughout an observation periodc of 10 days, or if animal is killed humanely and found to be negative for rabies by appropriate laboratory techniques


Single or multiple transdermal bites or scratches. Contamination of mucous membrane with saliva (I.e. licks)

Administer rabies immunoglobulin and vaccine immediately. Stop treatment if animal remains healthy throughout an observation periodc of 10 days, or if animal is killed humanely and found to be negative for rabies, by appropriate laboratory techniques

a. Exposure to rodents, rabbits and hares seldom, if ever, requires specific anti-rabies treatment.

b. If an apparently healthy dog or cat, in or from a low risk area is placed under observation, the situation may warrant delaying initiation of treatment.

c. This observation period applies only to dogs and cats. Except in the case of threatened or endangered species, other domestic and wild animals suspected as rabid should be killed humanely and their tissues examined using appropriate laboratory techniques.

  1. Different types of antirabies vaccines
    The different types of antirabies vaccines are as follows:
    1. Nerve tissue vaccines: Semple’s vaccine, etc.
    2. Avian embryo vaccine: Chick or duck embryo vaccines
    3. Primary cell culture vaccines: Human diploid cell vaccine.
  2. Schedule for Purified Chick embryo cell culture vaccine
    The dosage depends on whether it is pre exposure or post exposure prophylaxis. For pre exposure prophylaxis, 3 doses are given at weekly intervals followed by a 4th dose 1-3 months after the last primary dose. A booster is repeated every 2 years. For post exposure prophylaxis, the vaccine is given on days 0, 3, 7, 14, 30 and 90 days after exposure.
  3. Pre-exposure prophylaxis in Rabies:- Pre-exposure prophylaxis is given in cases of persons who are at high risk of infection such as dog catchers, veterinary personnel and lab workers. Three doses of Purified embryo vaccines or Human Diploid Cell vaccines are used. Semple vaccine should not be used for pre-exposure prophylaxis because of the risk of side effects.
  1. Anthrax
    Is primarily a disease of animals and occurs in man in 3 forms: Cutaneous form (in hide handlers), pulmonary form (wool sorters disease) and intestinal form. Pulmonary form can also occur by inhalation of anthrax spores and this is also used as a method of biological warfare.
  2. Hepatitis






Enterovirus 72




Hepadna Virus


Parenteral, Sexual






Viriod like







  1. Incubation period of hepatitis A and hepatitis B 15-50 days and 50-150 days respectively.
    Hepatitis B is transmitted through body fluids including blood and through sex where exchange of body fluids takes place. The routes of transmission can be categorized as follows:
    1. Parenteral or percutaneous: Through infected blood, blood products, syringes, transfusion apparatus, etc.
    2. Vertical or perinatal spread: Mother to infant transmission can occur when the mother is a chronic carrier or suffers from acute infection during the first trimester of pregnancy. The infection can also occur during passage through the birth canal or during the post-natal period due to close contact.
    3. Permucosal spread: Blood, saliva, vaginal fluids and semen are infective.
  2. Hepatitis B (serum hepatitis)
    Hepatitis B is a liver disease caused by the hepatitis B virus (HBV). The virus can cause lifelong infection, cirrhosis (scarring) of the liver, liver cancer, liver failure and death.
    1. Anyone can get hepatitis B, greater risk if:-
      1. ​Have sex with someone infected with HBV.
      2. Have multiple sex partners.
      3. Are a man and have sex with men.
      4. Have ever been diagnosed with a sexually transmitted disease.
      5. Are an injection drug user.
      6. Live in the same house with someone who has lifelong (chronic) HBV infection.
      7. Are a health care or public safety worker who has contact with human blood.
      8. Are an infant born to an HBV-infected mother.
      9. Are a hemodialysis patient.
      10. Are an infant/child or immigrant from areas with high rates of inf.
    2. ​Hepatitis B virus can be found in the blood and, to a lesser extent, saliva, semen and other body fluids of an infected person. It is spread by direct contact with infected body fluids; usually by needle stick injury or sexual contact. Hepatitis B virus is not spread by casual contact.
    3. The symptoms of hepatitis B include fatigue, poor appetite, stomach pain, fever, nausea, vomiting and occasionally joint pain, hives or rash. Urine may become darker in color and then jaundice (a yellowing of the skin and whites of the eyes) may appear. Adults are more likely than children to develop symptoms; however, up to 50 percent of adults who have acute infection do not have any symptoms.
    4. The symptoms may appear six weeks to six months after exposure, but usually within four months.
      The virus can be found in blood and other body fluids several weeks before symptoms appear and generally persists for several months afterward. Approximately 10 percent of infected adults may become long-term (chronic) carriers of the virus. Infants infected at birth have a 90 percent chance of becoming chronically infected.
  3. Hepatitis A (infectious hepatitis)
    The symptoms of hepatitis A may include an abrupt onset of fever, malaise, loss of appetite, nausea,  stomach pain, dark-colored urine and jaundice (a yellowing of the skin and whites of the eyes). The disease is rarely fatal and most people recover in a few weeks without any complications. Adults have signs and symptoms of illness more often than children. Infants and young children tend to have very mild symptoms and are less likely to develop jaundice than are older children and adults. Not everyone who is infected will have all of the symptoms. The symptoms commonly appear within 28 days of exposure, with a range of 15-50 days.
    The contagious period begins about a week or two before the symptoms appear and is minimal the week after the onset of jaundice.
  1. XVIII. Tetanus (lockjaw)
    1. Tetanus, commonly called lockjaw, is a bacterial disease that affects the nervous system.
    2. Tetanus is contracted through a wound which becomes contaminated with the organism.
    3. It is not transmitted from person to person. Hence Herd immunity is not protective.
    4. The tetanus germ is present throughout the environment and is commonly found in soil contaminated with manure.
    5. A common first sign of tetanus is muscular stiffness in the jaw (lockjaw), followed by stiffness of the neck, difficulty in swallowing, rigidity of abdominal muscles, spasms, sweating and fever.
    6. The incubation period is usually eight days but may range from three days to three weeks. Shorter incubation periods are associated with more heavily contaminated wounds. Recovery from tetanus may not result in immunity. Second attacks can occur and immunization is indicated after recovery.
    7. Complications include spasm of the vocal cords and/or spasms of the respiratory muscles causing interference with breathing. Other complications include fractures of the spine or long bones, hypertension, abnormal heartbeats, coma, generalized infection, clotting in the blood vessels of the lung, pneumonia and death.
  1. Strategy for neonatal tetanus elimination.
    1. Increase and sustain high coverage levels with two doses or in booster dose of IT in pregnant woman.
    2. Increase proportion of deliveries by trained personnel; intensify dais training.
    3. Supply disposable delivery kits to ensure clean practices for domiciliary deliveries.
    4. Implement essential new born care, including cord care, to reduce risks of neonatal tetanus.
    5. Strengthen surveillance system and undertake follow up action in areas from where cases are reported.
    6. Continue IEC activities to promote clean deliveries.
  2. Five Clean Practices
    1. Clean surface for delivery.
    2. Clean hands of the attendant.
    3. Clean blade for cutting the cord.
    4. Clean cord tie.
    5. No applicants on the cut stump of the cord (clean cord).
  1. Neonatal tetanus elimination (Classification of districts) –
  2. NT high risk –
    1. Rate > 1/1000 live births or
    2. TT 2 coverage < 70% or
    3. Attended deliveries < 50%
  3. NT control –
    1. Rate < 1/1000 live births &
    2. TT 2 coverage> 70% &
    3. Attended deliveries> 50%
  4. NT elimination –
    1. Rate < 0.1/1000 live births &
    2. TT 2 coverage> 90% &
    3. attended deliveries> 75%
  1. Common diseases transmitted by mosquitoes in IndiaThe common diseases transmitted by mosquitoes in India are malaria (anopheles), filarial, JE and West Nile fever (Culex), Malayan filariasis and Chikungunya fever (Mansonia) and dengue, yellow fever, DHF and Chikungunya fever (Aedes).
    1. Malaria
      1. Advice on chemoprophylaxis for malaria will you give to a foreigner visiting India
        Chloroquine 300 mg once a week starting 2 weeks before arrival or latest on the day of arrival and continued for 4-6 weeks after leaving the country is useful if there is no resistance to chloroquine in the area to which the foreigner is traveling. Sulfadoxine – pyrimethamine combination or mefloquine can also be taken if chloroquine resistance is reported.
      2. Spleen rate in malaria
        1. Children aged 2 – 10 years are examined for enlargement of spleen and areas are classified according to endemicity as indicated by the spleen rate:
        2. Below 10% - Non endemic
        3. 10 – 25% - Hypo endemic
        4. 25 – 40% - Endemic
        5. 40% - Hyper endemic.
      3. Indices for blood surveys for malaria
        The main indices are:
        1. Infant parasite rate: It is a good indicator of recent infection Q and is measured by proportion of blood smears of infants positive for malarial parasite.
        2. Children parasite rate: Here blood smears of children aged 2-10 years are examined.
        3. Annual parasite index: This is the most common index used currently. It is defined as the number of confirmed malaria cases per 1000 persons in an area per year.
        4. Slide positivity rate: Proportion of slides examined which are positive for the malarial parasite.
        5. Slide falciparum rate: Proportion of slides examined which are positive for falciparum species.
        6. Annual Blood Examination Rate: The number of blood slides examined per 100 population.
          • ​​An ABER of 10% is warranted for good coverage of the population under surveillance.
        7. Monthly blood examination rate: This should be 1% during the non-transmission season and 2% during the transmission season (July – Oct) in areas under active surveillance and 15% and 20% respectively (as a proportion of new OPD cases) in passive surveillance zones.
        8. Annual Parasite Incidence is defined as the number of confirmed malaria cases per 1000 persons in an area per year. It is the most sensitive index in use currently.
        9. Annual Blood Examination Rate
          This is a monitoring tool to ensure that adequate number of blood slides have been collected. The workers should have collected blood smears equivalent to > 10% of the population residing in an area. This is based on the expected load of fever cases in a community in a year.
    2. Japanese Encephalitis
      1. It is a zoonosis, affects mainly animals, incidentally to man. Man is incidental dead end host. (Man to man transmission does not occur), Subclinical infection is seen.
      2. Horses show symptoms.
      3. Culex tritaeniorhychnus (or C. Vishnuvi) is main vector.
      4. Rice field is breeding place (zoophilic).
      5. Case fatality rate is 20 - 40 % (average 30%).
      6. Re-vaccination required after 3 yrs.
      7. Death occurs in about 9 days (3 x 3)
      8. Vaccination required for children < 3 yrs.
      9. Spraying up to 3 km range.
      10. Immunity develops in 30 days, persist for 3 yrs
JE vaccine
  1. Nature: 3 types
    1. ​Mouse brain derived inactivated vaccine.
    2. Cell culture derived inactivated vaccine.
    3. Cell culture derived live attenuated vaccine.
  2. ​Dose & schedule: (live attenuated vaccine) – 0.5ml sc at insertion of deltoid. It shall be given to a child at the age of 8 months, 2 yrs, & 7 yrs respectively.
  3. Cold chain: +2 - +8*C.
  4. Side effects: live attenuated – transient fever (<2d), sporadic skin rashes.
  5. C/I: fever, acute infections, otitis media, active TB, cardiac, renal & hepatic ds, immunodeficient individuals, pregnancy, h/o allergy or epilepsy.
  1. Chikungunya fever
    Till 10 October 2006, 151 districts of eight states/provinces of India have been affected by chikungunya fever.
    1. The affected states are Andhra Pradesh, Andaman & Nicobar Islands, Tamil Nadu, Karnataka, Maharashtra, Gujarat, Madhya Pradesh, Kerala and Delhi.
    2. More than 1.25 million cases have been reported from the country with 752,245 cases from Karnataka and 258,998 from Maharashtra provinces. In some areas attack rates have reached up to 45%.
  1. Chikungunya and Dengue fevers
    The clinical manifestations of chikungunya fever have to be distinguished from dengue fever.
    Co-occurrence of both fevers has been recently observed in Maharashtra state of India thus highlighting the importance of strong clinical suspicion and efficient laboratory support.
  2. Laboratory Diagnosis
    The clinical manifestations of chikungunya fever resemble those of dengue fever.
    Laboratory diagnosis is critical to establish the cause of diagnosis and initiate specific public health response.
  3. Treatment
    1. Chikungunya fever is not a life threatening infection.
    2. Symptomatic treatment for mitigating pain and fever using anti-inflammatory drugs along with rest usually suffices.
    3. While recovery from chikungunya is the expected outcome, convalescence can be prolonged (up to a year or more), and persistent joint pain may require analgesic (pain medication) and long-term anti-inflammatory therapy.
  4. Prevention and control
    1. No vaccine is available against this virus infection.
    2. Prevention is entirely dependent upon taking steps to avoid mosquito bites and elimination of mosquito breeding sites.
    3. To avoid mosquito bites:
      Wear full sleeve clothes and long dresses to cover the limbs;
      Use mosquito coils, repellents and electric vapour mats during the daytime;Use mosquito nets – to protect babies, old people and others, who may rest during the day. The effectiveness of such nets can be improved by treating them with permethrin (pyrethroid insecticide). Curtains (cloth or bamboo) can also be treated with insecticide and hung at windows or doorways, to repel or kill mosquitoes.
      Mosquitoes become infected when they bite people who are sick with chikungunya. Mosquito nets and mosquito nets and mosquito coils will effectively prevent mosquitoes from biting sick people.
  5. To prevent mosquito breeding
    1. The Aedes mosquitoes that transmit chikungunya breed in a wide variety of manmade containers which are common around human dwellings.
    2. These containers collect rainwater, and include discarded tires, flowerpots, old oil drums, animal water troughs, water storage vessels, and plastic food containers.
    3. These breeding sites can be eliminated by
      • ​​Draining water from coolers, tanks, barrels, drums and buckets, etc.;
      • Emptying coolers when not in use;
      • Removing from the house all objects, e.g. plant saucers, etc. which have water collected in them
      • Cooperating with the public health authorities in anti-mosquito measures.
  1. Dengue fever
    (breakbone fever, dengue hemorrhagic fever)
    1. Dengue fever is a mosquito-borne disease caused by a virus. The disease is mainly tropical in origin but occasionally residents or visitors from other countries may arrive in this country with dengue fever.
    2. Dengue fever may occur in people of all ages who are exposed to infected mosquitoes. Dengue fever is spread by the bite of infected Aedes mosquitoes.
    3. Dengue fever is characterized by the rapid development of a fever that may last from five to seven days with intense headache, joint and muscle pain and a rash. The rash develops on the feet or legs three to four days after the beginning of the fever. The hemorrhagic form of dengue fever is more severe and associated with loss of appetite, vomiting, high fever, headache and abdominal pain. Shock and circulatory failure may occur. Untreated hemorrhagic dengue results in death in up to 50 percent of cases.
    4. Dengue fever may occur from three to 14 days after exposure to an infected mosquito, commonly within four to seven days.
    5. Infection with one of the four strains of dengue virus usually produces immunity to that strain but does not provide protection against the other strains.
    6. There is no specific treatment available. Intravenous fluids and oxygen therapy are often used for patients who experience shock during their illness.
  1. Food Poisoning
Some important facts about other types of food poisoning are mentioned below:
  1. Salmonella food poisoning
    Salmonella food poisoning is characterized by an incubation period of 12-24 hours, abdominal pain, diarrhea, vomiting and fever. The organisms most commonly multiply rapidly in animal foods like milk and milk preparations, meat, fish, eggs, ice creams, puddings, pastries, sausages and meat pies, etc. and so history of intake of such foods is elicited.
  2. Botulism
    In botulism, change of voice, diplopia, ptosis, cranial nerve palsies and obstinate constipation are observed. History of consumption of tinned food is usually observed. An incubation period of 12-36 hours is seen. Death usually occurs in 3- 7 days and mortality is high (40%).
Dracunculiasis is a vector-borne parasitic disease. Man acquires infection by drinking water containing cyclops harboring the infective stages of parasite. The adult parasite inhabits the subcutaneous tissue mainly in the legs. India has been declared free of guinea worm disease. Asia is now free of the disease since February 2000. The main endemic areas of the disease are Sudan, Ghana and Nigeria.

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