Evaluation of newly isolated probiotics in the protection against experimental intestinal trichinellosis.

The potential use of probiotics in controlling enteric infections has generated tremendous interest in the last decade. The protective efficacy of seven oral doses of two newly isolated Egyptian probiotic strains; Lactobacillus acidophilus P110 (L. acidophilus) and Lactobacillus plantarum P164 (L. plantarum) versus Lactobacillus casei ATCC 7469 (L. casei) - against experimental intestinal trichinellosis - was assessed via parasitological, immunological and histopathological parameters, after verifying their in vivo safety and intestinal colonization. Parasitologically, the highest adult count reduction was observed in L. plantarum-fed infected sub-subgroup (56.98, 65.42 and 69.02%) - on the 5th, 12th and 17th days post infection (P.I.), respectively. Lesser percentage reductions were recorded in both the L. casei-fed infected sub-subgroup (36.19, 23.68 and 31.58%) and L. acidophilus-fed infected sub-subgroup (36.50, 11.8 and 7.61%) at the same intervals. On the 28th day post challenge, the highest larval count reduction was in L. plantarum-fed infected sub-subgroup (87.92%). While lower percentage yet still significant were observed in the L. casei-fed infected (74.88%) and L. acidophilus-fed infected sub-subgroups (60.98%). Immunologically, serum IFN-γ levels in the probiotic-fed non infected sub-subgroups were higher than those in the probiotic-fed infected sub-subgroups. Both showed higher levels of IFN-γ than the non probiotic-fed sub-subgroups. Histopathologically, intestinal sections of the probiotic-fed infected sub-subgroups showed amelioration of the inflammation and damage resulting from Trichinella spiralis (T. spiralis) infection. Results indicate that, through mechanical and immunological mechanisms, L. plantarum showed parasitological and histopathological protective superiority with respect to both L. casei and L. acidophilus against murine T. spiralis infection.

Congenital trichinellosis in experimentally infected mice.

The present study aimed at allocating the time during pregnancy at which transplacental transmission of Trichinella spiralis (T. spiralis) larvae took place. Swiss albino mice were infected at different durations of pregnancy; five days before mating, on gestation day zero and five days after mating. Furthermore, to study the effect of immunosuppression on transplacental transmission, half of the experimental mice were immunosuppressed using cyclophosphamide drug (Endoxan). The percentage of infected uteri, embryos and placentas and the mean larval count were calculated on day 8 post infection (PI). Moreover, the percentage of infected offspring and the mean larval count in their muscles were estimated on day 30 PI. The results of the present study revealed that, transplacental transmission of T. spiralis could occur in offspring of mice when their mothers are infected before or after pregnancy. This was documented by the presence of larvae in the muscles of offspring. However, the rate of this transmission increased when the mothers are infected at late pregnancy whether they were immunosuppressed or not. The administration of the immunosuppressive drug whether before or after pregnancy increased the rate of infection and the mean larval count in both uteri of mothers and muscles of their offspring. A higher percentage of abortion was demonstrated in females infected before mating in different studied groups.

Effect of topical agents on cercariae of Schistosoma mansoni.

DEET (N, N-diethyl-m-toluamide) is one of the reliable and most widely used insect repellents. The present work was planed to evaluate the effect of free DEET, controlled release DEET and white precipitate ointment on the viability of cercariae of S. mansoni in-vitro. They were also topically applied to mice to study their efficiency in preventing cercarial skin penetration. Free DEET and controlled release DEET formula caused immobilization and death of cercariae within twenty and five minutes respectively. The number of adults detected after application of free DEET and white precipitate ointment to mice skin prior to infection were significantly lower than the control group. When controlled release DEET was applied no adults could be detected indicating failure of cercariae to enter through the skin. This was confirmed by histopathological study of the liver which was free of granuloma. Scanning electron microscopy revealed tegumental changes in cercariae exposed to both free DEET and controlled released DEET. So, topical application of any of the three chemicals was effective in controlling S. mansoni infection. The best was with controlled release DEET.