Schistosoma japonicum in the pig: the influence of age on the host/parasite relationship.

The current study sought to elucidate a possible association between age and susceptibility to a primary infection with Schistosoma japonicum in pigs. Sixteen Landrace/Yorkshire crossbred specific pathogen-free pigs in three different age groups (group A-C), aged approximately 7, 24 and 37 weeks at the beginning of the experiment, were infected by intramuscular injections of 1,000, 1,500 or 2,400 cercariae, respectively. Fecal egg counts were obtained twice weekly from six to eight weeks post infection (wpi), and the pigs were killed 11 wpi. The number of worms collected were counted and sexed subsequent to perfusion. Tissue egg counts were estimated on samples from the liver. The worm recoveries for group A, B and C were 3.2%, 8.1% and 3.8%, respectively. No differences were observed between the male/female ratios of the three groups. The fecundity parameters, ie, fecal egg counts per mature female and liver egg counts per mature female, showed no significant differences between the three age groups. The results did not indicate any difference in susceptibility between the different age-groups of pigs to a primary infection with S. japonicum.

The prevalence and control of soil-transmitted nematode infections among children and women in the plantations in Sri Lanka.

OBJECTIVE: To determine the prevalence of soil-transmitted nematode infections among children and to assess the magnitude of nematode infections among women in the reproductive age group. DESIGN: Cross-sectional study. SETTING: 14 government owned plantations in the up-country and low-country regions of Sri Lanka. SUBJECTS: 1614 children 3 to 12 years of age and 246 women 18 to 44 years selected using a multi-stage random sampling technique. MEASUREMENTS: Egg count from stool samples collected from subjects using the quantitative Kato-Katz technique; percentage of children and women infected. RESULTS: 89.7% of the children and 86.2% of the women had at least one type of soil-transmitted nematode infection. Ascaris lumbricoides was the most common infection (77.0% of the children and 69.5% of the women). 69.4% of the children and 56.5% of the women had Trichuris trichiura infection and 23.2% of the children and 41.4% of the women had hookworm infection. Hookworm infection was much more common in the low country plantations. CONCLUSION: The high prevalence rates reflect widespread faecal contamination of the environment in the plantations due to poor and congested housing conditions and insufficient sanitary facilities. As the physical environment is not likely to change in the short term, the strategy for control of soil-transmitted nematode infections should focus on regular deworming of children and health education. A control program based on these principles was initiated in the estate sector after this study was completed.

The efficacy of three anthelmintic drugs given in a single dose.

OBJECTIVE: To compare the efficacy of a single dose mebendazole 500 mg from the original manufacturer and a formulation locally produced by State Pharmaceuticals Manufacturing Corporation of Sri Lanka and albendazole 400 mg in mass treatment of soil-transmitted nematode infections. DESIGN: Randomised trial. SETTING: Government owned plantations in low-country regions of Sri Lanka with poor sanitary facilities. SUBJECTS: 399 children 3 to 15 years of age infected with at least one type soil-transmitted nematode. INTERVENTION: Mebendazole 500 mg or albendazole 400 mg given as single dose treatment. MEASUREMENTS: Cure rates and egg reduction rates calculated from egg counts of pre- and post-treatment stool samples using the quantitative Kato-Katz technique. RESULTS: All three drugs were effective against Ascaris infection with cure rates above 95%. The efficacy against Trichuris trichuria was uniformly poor. For hookworm infection albendazole appeared to be more effective in a single dose with cure rates of 77.9% compared with 28.7% and 35.8% for the two mebendazole formulations; corresponding egg reduction rates were 95.4% compared with 72.0% and 74.5%. CONCLUSION: Albendazole is the drug of choice for mass deworming where hookworm disease is prominent. There was no statistically significant difference between the original and locally produced mebendazole.