Infectivity of Trichinella spiralis muscle larvae recovered from pig carcasses

PASQUALETTI, M.; FARIÑA, F.; ROSA, A.; CARDILLO, N; RIBICICH, M

Conferencia; 14th International Conference on Trichinellosis; 2015

Trichinellosis is an endemic disease in Argentina, with pork being the most important animal species usually involved in human outbreaks. Pig farming and home slaughtering as well as home sausage making, are some very rooted traditions in Argentina, that when are not made properly, contributes to the perpetuation of this disease. The production of free?ranging pigs has increased in many countries, including Argentina. Pig farming with low sanitary and hygienic conditions, where animals are fed with food scraps or other forms of meat? containing animal wastes, allows Trichinella spiralis to infect domestic pigs. The aim of the present work is to assess the role played by porcine infected meat in the perpetuation of this parasite in the environment. A male pig, hybrid (Landrace x Yorkshire) was infected per os with 2,000 muscle larvae of T. spiralis. In order to prepare the inoculums, larvae were recovered from a laboratory mouse by enzymatic digestion. The pig was allowed to acclimatize to the new environment, prior to parasite infection. At 120 days post inoculation (p.i) the pig was euthanized and eviscerated, according to bioethics rules. The carcass was cut into two identical pieces. One of the carcasses was placed on the surface of a plastic container which had previously been filled with soil. The second carcass was buried in another box. Both of them were covered with fine mesh wire and were located in an enclosed area with adequate ventilation, exposed to sunlight, and protected from rain. Weekly, muscle samples were taken from each carcass and were subjected to artificial digestion. The recovered larvae were counted and inoculated to mice (300 larvae/mouse). After 6 weeks, mice were euthanized and digested to confirm the intensity of infection. The reproductive capacity index was calculated for each mouse. The study lasted 9 weeks, with a mean temperature of 16ºC and the humidity ranging from 88 % to 36 %. Infective capacity remained for 5 weeks in the samples belonging to the carcass that was on the surface, and 4 weeks in the samples belonging to the carcass that was buried. There were no significant differences between groups (p>0.05). Our study demonstrates that T. spiralis has the ability to remain infective in pig carcasses for several weeks under natural conditions, which would be a key link in the epidemiology of the disease.