Zoonoses: challenges and strategies.

Zoonoses account for about four fifth of the human infections. The health problems posed by these seem to be increasing. Newer problems are recognised. Older and endemic problems appear in different forms. Zoonosis management is getting complex and complicated. Attention on their control and eradication is essentially required.

Mechanisms of Bacillus cereus enteropathy.

Three strains of Bacillus cereus isolated from sausages (Salami and Trekker, RANBAC, Ranchi) produced enterotoxin which caused vascular permeability in skin and haemorrhage in the ligated ileal loops of rabbits. Histopathological studies revealed haemorrhage and congestion in submucosa, mononuclear cell infiltration in lamina propria and submucosa and villous atrophy. Histochemical studies ruled out the effect on mitochondrial enzymes of intestinal epithelial cells. Purified enterotoxin given intradermally to rabbits caused severe necrotic reaction at the site of injection and death within 4 hr. Histopathological changes observed in liver included congestion of portal veins and sinusoids, vacuolar degeneration of hepatocytes, and hyperplasia of bile ducts. These suggested that B. cereus enterotoxin affected the capillaries of blood vessels locally and also systemically resulting into release of proteinaceous exudates and red blood cells.

Haemagglutinin production by enterotoxigenic strains of Clostridium perfringens type A.

Thirty-nine enterotoxigenic cultures of Clostridium perfringens type A were studied for enterotoxin and haemagglutinin production. Enterotoxin was quantitated by sandwich ELISA and DOT-ELISA techniques and haemagglutinin titres were determined using sheep and human erythrocytes. Haemagglutinins from only six cultures reacted against both sheep and human erythrocytes; a further 13 reacted only against human erythrocytes, and another five only against sheep cells.

DOT-enzyme linked immunosorbent assay for detection of Clostridium perfringens type A enterotoxin.

A procedure, which we have termed DOT-ELISA, to detect Clostridium perfringens type A enterotoxin on nitrocellulose paper is described. Seventy eight preparations from 39 cultures of C. perfringens type A were tested simultaneously by this and by Plate-ELISA methods. The results were comparable. DOT-ELISA detected as little as 0.02 micrograms of purified enterotoxin and 0.13 micrograms of enterotoxin in cell-free culture supernatant. As little as 0.02 micrograms purified enterotoxin mixed with human faeces could be detected specifically. The method is simple and does not require an ELISA reader.

Hydrophobia cases and post-exposure anti-rabic vaccines in Ranchi, Bihar (1979-84).

Rabies is endemic in India. The status of Rabies at the national level is difficult to present because of inadequate reporting system. However, a national awareness has been created over the years (Anonym 1968, 1970, 1974, 1977, 1978, 1980, 1983, 1984a and 1984b). National Canine Rabies Control Programme finalised by the National Committee on Zoonoses has been taken up recently by the Ministry of Agriculture, Government of India. Use of mass communication media like newspaper, radio and television has also been started. The department of Veterinary Public Health & Epidemiology started working on Rabies in 1979. Observations of the first six years constitute this paper.

Direct immunoperoxidase test in the diagnosis of rabies--an alternative to fluorescent antibody test.

Direct immunoperoxidase test was run parallel to fluorescent antibody test using known rabies-positive and negative materials. Both the tests had 100.0% sensitivity and specificity when mice brain infected with CVS strain of Rabies virus was used. With the field samples and the mice brains infected with these, the sensitivity of direct immunoperoxidase test and also of fluorescent antibody test dropped a little, giving an overall sensitivity of 95.3 and 99.0 percent respectively. The standardization of immunoperoxidase test is described and the results discussed.

Urban dog rabies endemicity and dog physiology.

The frequency of dog-bite cases receiving anti rabic vaccine was studied for five years. Their monthwise frequency was studied. Six opportunities of contact in any calendar year which might lead to rabies transmission were identified to be provided by dog's physiological behaviour. A prediction on this basis of the frequency of months when dog rabies would appear, was brought out. This was compared with observed frequency. These are discussed.

Pseudomonas aeruginosa infection-evidences of amphixenosis.

In the present investigation many of the isolates of Pseudomonas aeruginosa from human beings, poultry and pigs fell in the same aeruginocine type. Aeruginocine A1 of Ps. aeruginosa was isolated from pigs and also from one of the pig attendants on the farm. Majority of the strains of Ps. aeruginosa of the same aeruginocine type also exhibited similar drug sensitivity patterns. The organism appeared to be polyphagous in nature and infection with this agent may be considered as amphixenosis.

Use of enzyme linked immunosorbent assay (ELISA) in the quantitation of Clostridium perfringens type A enterotoxin and antienterotoxin antibodies.

ELISA procedure for quantitation of enterotoxin of Clostridium perfringens type A was worked out. It was possible to detect as little as 0.0022 microgramme of enterotoxin. When applied to quantitate the enterotoxin in laboratory contaminated faeces and cooked minced beef, ELISA detected as little as 0.024 microgramme of enterotoxin. ELISA procedure for determination of titre of antibodies to enterotoxin was also developed using hyperimmunised rabbit and sheep sera. It was possible to use this procedure in sero-survey.

Serological evidence of persistence of Japanese encephalitis virus activity in Bihar, India.

A total of 64 sera samples from ducks, 212 from 245 fowls, 1 from 16 sparrows and 5 from human were examined for HI and CF antibodies to Japanese encephalitis (JE), West Nile (NW), Dengue-2 (DN-2), and Chikungunya (CHIK) viruses. The results were compared with those obtained earlier while examining pigs' sera from the same area. The results revealed that ducks, fowls and peridomestic sparrows possessed antibodies to JEV. JEV activity in ducks and fowls was significantly higher compared to its activity in pigs in the same area reported earlier indicating persistence of its activity.

Food borne infection with Clostridium perfringens type A.

Clostridium perfringens type A is one of the four most important bacterial agents causing food poisoning. Differential biochemical characterization appears to be important because of certain confounding species. Both the heat sensitive and resistant spore forming strains cause food poisoning. Ubiquitous nature, ability to contaminate carcass intravitally, thermal resistance of spores, relatively short generation time at high incubation temperature, survival in chilled and frozen meat and ability to overcome stomach acid barrier makes Cl. perfringens type A a common agent of food borne infection. Enteropathy is mediated through enterotoxin synthesised in vivo during sporulation. The enterotoxin is relatively insensitive to intestinal enzymes and is cytotoxic. The membrane bound transport enzyme, Na+K+-ATPase seems to be affected resulting into fluid accumulation in the ligated ileal loop of rabbit. Agglutination test using vegetative cell antigen is the commonly used epidemiological tool. New tools such as agglutination test with antispore serum, precipitin-in-gel test with anti-enterotoxin serum, active and passive bacteriocin, bacteriophage and biotyping have been developed using standard strains and isolates of c. perfringens type A from foods, food poisoning and others. Except for bacteriophage typing, others appears to be useful alone or in combination, though these require to be tested in field investigations.

Serological evidence of Japanese encephalitis virus activity in Bihar.

Serum samples from 404 pigs originating from eight districts of Bihar were examined for haemagglutination-inhibiting and complement fixing antibodies of Japanese Encephalitis, Dengue-2, West Nile and Chikungunya viruses. Japanese Encephalitis viral infection was found to be widely prevalent compared to other arboviruses tested. RElatively large number of pigs had antibodies to JEV only (i.e. monoconverters). High geometric mean titre to JEV was observed. These observations appear to be of epidemiologic significance to the 1978 epidemic of encephalitis in Bihar. Epidemic of encephalitis was reported in 1978 from several states of India including Bihar. The only evidence of the activity of Japanese Encephalitis in Bihar came from Khan and Banerjee who found neutralizing antibodies in ardeid birds from Asansol - Dhanbad regions. Evidences are presented in this paper on the prevalence of Japanese Encephalitis in eight districts including Dhanbad of Bihar.