Transmission studies on Trichinella species isolated from Crocodylus niloticus and efficacy of fenbendazole and levamisole against muscle L1 stages in Balb C mice

Forty-four Balb C mice, aged 18 weeks were infected with crocodile (Crocody lus niloticus)-derived Trichinella species. Of the infected mice, 32 were r andomly divided into two groups each containing equal numbers of males and females; levamisole treated group and fenbendazole treated group. Each grou p was randomly subdivided into two subgroups as follows: levamisole group ( subgroup 1:treated with levamisole on day 35 post infection, and subgroup 2 : treated with levamisole on days 35 and 42 post infection) and fenbendazol e group (subgroup 1: treated with fenbendazole on day 35 post infection and subgroup 2: treated with fenbendazole on days 35 and 42 post infection). T he first subgroups treated on day 35 post infection were slaughtered on day 42 post infection and the second subgroups were treated on day 35 and day 42 post infection and slaughtered on day 49 post infection. Two female mice were infected a day after mating and were slaughtered together with the of fspring on day 64 post-infection. Ten infected control mice were given 1 mi distilled water orally as placebo, and five of these were slaughtered on d ay 42 post infection. The results showed that the mean reproductive capacit y index of this strain (RCI) in Balb C mice was 110. There was a significan t reduction (P < 0.01) in larval counts in the single treatment groups (day 35) and in the double treatment groups (days 35 and 42) for both anthelmin tics when compared the number of parasites in the control groups. After a s ingle treatment, levamisole reduced the infection by 79.9 % and fenbendazol e by 76.7 %. Following double treatments, levamisole reduced the infection by 95.5 % and fenbendazole by 99.1 %. There was evidence that the infected pregnant mice transmitted the parasite to their offspring. It is not certai n whether the parasite was transmitted congenitally or transmammary. Altern ative ways of controlling the parasite in crocodile farms in Zimbabwe are d iscussed.