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  1. Spherical, pleomorphic, 150-300nm
  2. Single stranded RNA, linear, nonsegmented, negative sense
  3. Enveloped, contains two different transmembrane glycoproteins
  4. HN/ H: may possess both haemagglutinin & neuraminidase activities
  5. F: membrane fusion & hemolysin activities
Characteristics of genera in the subfamilies of the family Paramyxoviridae
Property Paramyxovirinae Pneumovirinae
Paramyxovirus Rubulavirus Morbillivirus Pneumovirus
Parainfluenza 1,3 Mumps, parainfluenza 2,4 Measles RSV
Serotypes 4 1 1 1
Dia. of nucleocapsid (nm) 18 18 18 13
F protein + + + +
Hemolysin + + + -
Hemagglutinin HN HN H -
Hemadsorption + + + -
Neuraminidase HN HN - -
Inclusions C C N,C C
a. Para influenza virus :
  1. Infection acquired by droplets
  2. All parainfluenza viruses produce respiratory tract infections
  3. In infants & children: lower respiratory tract infection, pneumonia
  4. In older children (6 months to 5 years): Mainly type1 & in some cases type 2 cause laryngotracheobronchitis or croup
  5. Fever, cough, respiratory distress, emergency tracheostomy
    Laboratory diagnosis :
  6. Demonstration of viral antigen: Immunofluorescence staining
  7. Virus is isolated from throat swabs, nasopharyngeal washes or sputum through tissue         culture, viral growth detected by immunofluorescent staining
  8. Antibody detection: CFT, HAI, Nt, ELISA
  1. Disease of childhood
  2. Transmitted by respiratory secretions
  3. Virus multiplies in the upper respiratory tract and local lymph nodes, viremia occurs and virus spreads to many organs
  4. Major manifestation: painful swelling of one or both salivary glands 14-18 days after exposure
  5. Complications: meningoencephalitis, orchitis, oophoritis, pancreatitis, arthritis, myocarditis, renal dysfunction
  6. Natural mumps confers life long immunity
  7. Some patients may not develop parotitis
Sterility (due to orchitis) is not a common complication
  1. Laboratory diagnosis
  2. Isolation: tissue culture
  3. Serology: ELISA, IgM antibody detection
  4. Prophylaxis
  5. Live attenuated vaccine (Jeryl –lynn strain)  
c. Measles (rubeola) virus:
Contagious childhood disease spread by respiratory secretions
Virus gains access through respiratory route→multiplies locally→spreads to the regional lymph nodes→primary viraemia→dissemination of virus→multiplies in reticuloendothelial system→secondary viraemia→seeds epithelial surfaces of the body (skin, respiratory tract, conjunctiva)
  1. Clinical features
    Incubation period: 10-12 days
    Upper respiratory tract infection, fever, rhinitis, cough, conjunctivitis
  2. Koplik’s spots: small, 1-3mm diameter, bluish white spots surrounded by erythema seen on buccal mucosa
    After 1-2 days symptoms decline with the appearance of maculopapular rash which appears first on the cheek and then spreads to the rest of the body. In next 10-14 days rash fades with the desquamation of the skin
  3. Complications Otitis media, pneumonia
    Secondary bacterial infections
    Giant cell pneumonia in patients with impaired cell mediated immunity-Hecht pneumonia
    Acute post infectious encephalitis (1/1000 cases of measles)-immune mediated
  4. Subacute sclerosing panencephalitis (1/300,000 cases of measles)
    It occurs 5-15 years after an attack of measles. Due to a defective measles virus in neurons
    Progressive mental deterioration, involuntary movements, muscular rigidity, coma
    Invariably fatal High titres of measles antibody in CSF
  5. Laboratory diagnosis of measles
    Direct detection: Multinucleated giant cells, antigen (immunofluorescence) in nasopharyngeal aspirates
    Isolation: tissue culture, multinucleated giant cells containing eosinophilic inclusions in cytoplasm and nucleus, detection of growth by immunofluorescence
    Serology: IgM antibody by ELISA, CFT
  6. Prophylaxis
    Live attenuated vaccine, Edmonston-Zagreb strain
d. Respiratory syncytial virus
  1. Lacks both hemagglutinin and neuraminidase activities
  2. Contains only fusion (F) protein that results in the formation of multinucleated syncitia
  3. Responsible for 50% cases of bronchiolitis and 25% cases of pneumonia during first few months of life
  4. Infection is spread through respiratory secretions
  5. Lower respiratory infection (bronchiolitis, pneumonia) in infants less than 6 months of age
  6. Upper respiratory tract infection (cold) in older children and adults
  7. Immunocompromised transplant recipients, it may cause severe pneumonia
Treatment: Supportive care, ribavirin

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