Leprosy (Ref: Park 22nd edition; Pg:245,281,314)
Mass chemoprophylaxis or mass drug administration has been an accepted and recommended woy of controlling diseases like trachoma, yaws and filariasis however, the general applicability of chemoprophylaxis as a means of preventing leprosy and its control is still to be determined.
a. The value of chemoprophylaxis especially among contacts (mass drug treatment “Research” )of leprosy, has been the subject of study in India since 1963.
b. These studies, established that dapsone prophylaxis (at a dose of 1-4 mg per kg body weight per week) gave a protection among child contacts ranging between 35 to 53 per cent.
c. The prophylactic treatment was given for at least three years or until the index case in each household became bacteriologically negative.
d. Acedapsone (a long-acting repository sulphone) was also found to be as effective as DDS. Acedapsone has great operational advantages over DDS in view of the fact it involves only one injection (i.m.) every 10 weeks.
e. More recently, in India, a shorter course of acedapsone prophylaxis was tried (3 injections at intervals of 10 weeks to cover a period of 210 days), and was found to be effective (about 78 per cent protection .
In filariasis four major breakthroughs have occurred. The first of these is the development of safe, single-dose, annual drug treatment. Trials have proved that a single dose of DEC is very effective even two years after treatment. A single dose of ivermectin has proved to be equally effective. A combination of single dose of both drugs reduced microfilaraemia more than 95 per cent, 2 years after treatment.
In trachoma control, the main activity is chemotherapeutic intervention. The objective of chemotherapy is to reduce severity, lower the incidence and in the long run decrease the prevalence of trachoma. The antibiotic of choice is 1 per cent ophthalmic ointment or oily suspensiol1 of tetracyclines. Erythromycin and rifampicin have also been used in the treatment of trachoma. Treatment may be given to the entire community - this is known as mass treatment (or blanket treatment). In some programmes, selective treatment is chosen, in which case, the whole population at risk is screened, and treatment is applied only to persons with active trachoma
Mass treatment: A prevalence of more than 5 per cent severe and moderate trachoma in children under 10 years is an indication for mass or blanket treatment. The treatment consists of the application twice daily of tetracycline 1 per cent ointment to all children, for 5 consecutive days each month or once daily for 10 days each month for 6 consecutive months, or for 60 consecutive days . An alternative antibiotic is erythromycin.
1. From the practical point of view, one of the main difficulties is the need for repeated applications of the antibiotic over long periods of time. Emphasis is now being placed on the active participation of the community itself in trachoma control activities and on the utilization of village health guides (primary health care workers). This makes possible a wider coverage and a greater efficacy of the programme .
2. In case of yaws chemoprophylaxis is based on the following observations: A. treatment with a single injection of long-acting penicillin will cure infection B. the simultaneous treatment of all clinical cases and their likely contacts in the community will interrupt transmission in the community.
3. Benzathine penicillin G is the penicillin of choice. The dose of BPG is 1.2 million units for all cases and contacts, and half that dose (0.6 million units) for children under 10 years of age.
4. The WHO has recommended three treatment policies:
5. Total Mass Treatment: In areas where yaws is hyperendemic (I.e., more than "10 per cent prevalence of clinically active yaws), a great part of the population is at risk. The entire population including the cases should be given penicillin in the doses mentioned above
6. Juvenile Mass Treatment: In meso-endemic communities (5 to 10 per cent prevalence), treatment is given to all cases and to all children under 15 years of age and other obvious contacts of infectious cases
7. Selective Mass Treatment: In hypoendemic or areas of low prevalence (less than 5 per cent) treatment is confined to cases, their household and other obvious contacts of infectious cases.