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One thousand three hundred and seventy-five (1375) persons, who were vaccinated against Rabies with Purified Chick Embryo Cell (PCEC) vaccine from 1984 to 1993, were included in this ten-year longitudinal study, conducted to observe the consistency, immunogenicity, inocuity, safety and efficacy of PCEC vaccine under controlled trial and field conditions. The study period was divided into three phases. Phases I and II covered the premarketing controlled trial and Phase III the post-marketing serosurveillance study of the vaccine. During Phase I, fifteen healthy volunteers were given a pre-exposure regime of vaccine on Day 0, 7 and 21, and the rest 15, simulated post-exposure regime on Day 0, 3, 7, 14, 30 and 90. All the subjects had satisfactory antirabies antibody response with mean titres, of 7.08 and 5.72 I.U./ml respectively, and minimal side reactions. In the Phase II, from 1984-85, 56 persons with proven rabid animal bites were given post-exposure vaccination and all had satisfactory antibody titres with mean titre of 4.45 I.U./ml after 6th dose of vaccine and with minimal side reactions. 19 to 36 months follow up after vaccination revealed no vaccine failures. In the Phase III post-marketing field study conducted from 1985 to 1993, 1289 persons reported to our Centre for consulation and antirabies antibody titre estimation following PCEC vaccination. One thousand two hundred and fifty-two (1252) persons took post-exposure vaccination following bites by rabid animals, contact with an hydrophobia patient and 37 high risk personnel took pre-exposure vaccination.(ABSTRACT TRUNCATED AT 250 WORDS)

Fifty-five individuals bitten by rabid animals were administered purified vero-cell rabies vaccine (PVRV) at WHO Collaborative Centre for Rabies Epidemiology for South-East Asia at National Institute of Communicable Diseases, Delhi to test its immunogenicity, inocuity, safety and clinical efficacy. Fifty-two (94.5 per cent) of these individuals underwent complete course of treatment. Sera samples collected prior to the commencement of treatment showed all these persons to be sero-negative for antibody against Rabies virus. However mean titre of 2.44 I.U./ml, 7.76 I.U./ml and 10.77 I.U./ml were detected after third, fourth and sixth injections, respectively of PVRV. Persistance of protective titres of this antibody could be demonstrated even after 15 months of treatment. Of 327 inoculations, local and general reactions were observed after 10.6 per cent inoculations. All these cases were followed up for periods between 7 and 25 months and were, alive and healthy till the end of observation period, thereby proving the efficacy of the vaccine in preventing rabies.

Comparative evaluation of indirect fluorescent antibody test (IFAT) and Weil-Felix test (WFT) was carried out for detecting rickettsial antibodies in 102 patients with pyrexia of unknown origin (P.U.O.), 20 brucellosis cases and 20 normal healthy controls (N.H.C.). Of 102 sera of cases with P.U.O., antibodies against rickettsia could be detected in 11 (10.7 per cent) cases by IFAT and in 10 (9.8 per cent) cases by WFT, but amongst these 10 sera, antibodies could be detected only in six by IFAT. All 20 brucella positive sera were negative for rickettsia by IFAT but by WFT in 6 sera antibodies against rickettsia could be detected and 20 N.H.C. sera were negative by both the tests. Thus the advantages of IFAT over WFT in detecting antibodies against rickettsia in terms of sensitivity and specificity make it a more reliable test.

The demographic features of acute x sporadic viral hepatitis as diagnosed by specific markers of viral infection in four different cities in north and north-east India, were examined. Of 405 patients examined, 26 per cent had HB,Ag, 5.9 per cent IgM-anti-HAV antibody, and 8.4 per cent IgM-anti-HBc antibody. Hepatitis B occurred more frequently in male patients (76 per cent) compared to hepatitis A (54 per cent), and in the young adult age group (21-30 years), compared to the latter, which occurred predominantly in children (0-10 years). By using tests to detect HbsAg and IgM-anti-HBc antibody, this study found that hepatitis B accounted for 3 per cent and 8.8 per cent of clinically detected acute sporadic hepatitis in patients less than and older than 10 years of age respectively, which is in contrast with previously-reported rates from India. This study also suggests that many of the infections thought to have been due to HBV, may be due to NANB hepatitis virus. This study emphasizes the importance of specific laboratory tests to draw epidemiologic conclusions regarding hepatitis.

The sensitivity and specificity of three serological tests viz. indirect immunofluorescent antibody test (IFAT), enzyme linked immunosorbent assay (ELISA) and counterimmunoelectrophoresis (CIEP) for the diagnosis of Indian kala-azar were evaluated. Of the 209 patients in whom Leishmania donovani parasite could be demonstrated in bone marrow, 207 (99.04 per cent) could be diagnosed with IFAT, 203 (96.6 per cent) with CIEP and 208 (99.5 per cent) with ELISA. None of these serological tests was positive in 40 healthy individuals and 10 patients each with tuberculosis, toxoplasmosis and malaria. In only one out of 10 patients with malaria ELISA alone gave false positive result. Of the 119 patients who had clinical features simulating kala-azar but were negative for Leishmania donovani in bone marrow and responded to treatment other than that for Indian Kala-azar, IFAT, CIEP and ELISA were false positive in three (2.5 per cent), nil and three (2.5 per cent) cases, respectively. The use of serodiagnostic tests like ELISA for mass screening and CIEP in less well equipped peripheral laboratories is suggested.

Intimate and prolong contact between man and animal facilitates the transmission of various communicable diseases between them. These diseases (zoonoses) are more prevalent in developing countries especially in the rural areas. These diseases virtually stunt the economic and social growth also. Lack of authentic data and awareness regarding the occurrence of these diseases and their true impact on public health have acted as major obstacles in instituting adequate and effective control measures. The information available regarding the current status of few important zoonoses in India is being presented in this paper.

One thousand and thirty-six serum samples obtained from women with bad obstetric history (BOH) were subjected to detection of toxoplasma antibody by indirect immunofluorescent antibody test (IFAT) using whole promastigotes of Rh strain of Toxoplasma gondii as antigen. Thirtyone (2.99 per cent) samples were found to be positive (titre greater than or equal to 1:64). Of these 31 patients' sera 27 (87.09 per cent) showed rising titre of antibody when second samples were drawn after 4 weeks. Two hundred serum samples from general population were also assayed and only 2 (1 per cent) were found to be having toxoplasma antibodies in titre of 1:64. The observations suggest low prevalence of toxoplasmosis in and around Delhi which is in consonance with the food habits of local people and their infrequent contact/association with cats.

Delhi experienced an outbreak of cholera during July-August 1988 which affected residents from all walks of life. A total of 1824 laboratory confirmed cholera cases were detected in two months period at I.D. Hospital, Delhi alone. The number of cholera cases in July-August 1988 was 5-10 times that of the same period during the previous years in the Capital. The outbreak was caused by Vibrio cholerae Ogawa biotype ElTor. Majority of the laboratory confirmed cases (about 74 per cent) were seen in children under the age of 15 years. Though the cases were spread all over Delhi, almost three-fourths of total cases were reported from two specific zones (Shahdara and Civil Lines). Most of the isolates were sensitive to all antibiotics tested. The proportion of isolates resistant to furazolidone during this outbreak was substantially higher than in previous years suggesting that the outbreak may have been caused by the introduction of a new strain rather than proliferation of endemic strain. The salient features of the outbreak are discussed.

Search for livelihood makes many people move from kala azar endemic areas to metropolitans like Delhi from where indigenous cases have not been reported. During 1986-1989, 211 laboratory confirmed kala azar cases were detected in Delhi. Of these 202 (95.73 per cent) were from Bihar and remaining nine (4.27 per cent) belonged to Uttar Pradesh. Younger age groups were affected more and maximum cases (54.02 per cent) were in the age group of 5-15 years. Male:female ratio was 2:1. Fever (100 per cent) along with mass in abdomen (99.05 per cent) were the major presenting complaints. Splenomegaly was seen in all the patients whereas hepatomegaly was a feature in 184 (87.20 per cent) cases. Response to sodium antimony gluconate (SAG) was variable and number of injections administered reached upto 80 in some (23) cases. All 37 patients responded to pentamidine after two full courses of SAG failed to bring about any clinical and parasitological cure.

Sixty drinking water samples collected from various sources in different areas of Delhi during epidemic of cholera and gastroenteritis were analysed for bacteriological standards. Only 27 (45 per cent) samples were found to be satisfactory for human consumption. Remaining thirty-three (55 per cent) samples showed presence of coliform organisms with MPN value ranging from 10 to 1800+ per 100 ml. Among these positive samples, 31 (93.9 per cent) samples contained faecal coli. Twenty out of thirty (66.6 per cent) Hand pump, 9 out of 21 (42.8 per cent) Taps 2 out of 4 (50 per cent) Tube well and 2 out of 5 (40 per cent) of miscellaneous sources showed contamination with coliform organisms.