Current status of food-borne parasitic zoonoses in India.

Food-borne parasitic zoonoses have a major impact on the health and economy in developing countries in the tropics and sub-tropics. Complex socio-economic and socio-cultural factors impact on the maintenance of parasitic zoonoses. In addition to human disease, some of these parasites are responsible for economic loss to livestock production. Throughout India, problems of food-borne parasitic zoonoses differ because of varied food habits. Other factors, however, such as unhygienic living conditions, lack of education, poor personal hygiene, poverty and occupation, also contribute to the dissemination of parasitic infections. The present status of various food-borne parasitic zoonoses are briefly given here.

Prevalence of Sarcocystis in domestic pigs in India.

Muscle samples from 890 slaughtered pigs were examined for the presence of sarcocysts. A high prevalence rate of 67.98% was observed. Two types of microsarcocysts were recorded. The sarcocyst wall of one type had redial striations and the other possessed hair-like villar protrusions. The species were identified as Sarcocystis miescheriana and Sarcocystis suihominis; there was a slightly higher incidence of the latter species (47.11%) than of the former (43.14%). S. suihominis has been identified for the first time from pigs in India.

Toxicity of cyst extract of Sarcocystis fusiformis from buffalo in rabbits and mice.

The toxic effect of cysts of Sarcocystis fusiformis (of buffalo origin) in rabbits and mice have been studied. It is shown that inoculation of a 2 mg ml-1 concentration of protein of the macrosarcocyst extract (ME) into rabbits and mice was lethal. The toxic substance was thermolabile at greater than or equal to 60 degrees C for 30 min. Protease and trypsin caused inactivation, while papain did not affect the toxicity. ME was found to be non-dialysable, but precipitable. There was also no effect of a pH of 6-9, while pH 4-5 altered the toxicity and pH 10 only partially affected the toxic effect.

Effect of temperature on the infectivity of Sarcocystis miescheriana cysts in pork.

Sarcocysts of Sarcocystis miescheriana in the thigh muscles of pigs became non-infective to pups after heating infected pork in minute pieces at 60 degrees C for 20 min, 70 degrees C for 15 min and 100 degrees C for 5 min. Similar pieces of infected muscle tissues, when exposed to -4 degrees C for 2 days or -20 degrees C for 1 day, became non-infective to pups. The experiment suggests that pork containing sarcocysts of S. miescheriana, and possibly of S. suihominis, requires cooking at a minimum of 70 degrees C for 15 min or freezing at -4 degrees C for 2 days or -20 degrees C for 1 day for making it safe for consumption.

Spirometra sp. in a domestic cat in India.

Adult Spirometra sp. were found in an experimental cat. This is the first report from northern India. It is suggested that this infection may have resulted from the feeding of raw fish offal.