{'fraction_non_alphanumeric': 0.01834862385321101, 'fraction_numerical': 0.0024464831804281344, 'mean_word_length': 5.127340823970037, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Reappraisal of the guinea-pig as an experimental host for studies of schistosomiasis mansoni

Summary The guinea-pig has been reassessed as a potential laboratory host for Schistosoma mansoni. Twenty-six per cent of an infective cercarial population survive to maturity in this rodent and there are no gross fluctuations in worm burden subsequent to pairing of male and female parasites. Five day, 4-week and 6-week-old schistosomes grown in guinea-pigs have topographical features that are identical to those exhibited by similarly aged mouse worms, but different from those exhibited by rat worms. Schistosome eggs are never detected in the faeces of infected guinea-pigs, but they can be observed in the pulmonary, hepatic and intestinal tissues. Only 55% of the eggs that can be recovered from the intestinal tissues are viable, and some of these can be hatched to release miracidia that penetrate the intermediate snail host. Cercariae are sometimes liberated from infected snails, but in insufficient numbers to permit infection of naive guinea-pigs. The schistosome cycle cannot, therefore, be completed in this host. Collaterals are sometimes observed in the vasculature serving the rectum and kidneys of infected guinea-pigs and the fact that schistosome eggs are deposited in the lungs of these animals indicates that portal systemic anastomosis is a feature of the model. Pathology associated with cercarial invasion or egg deposition is not dissimilar to that described for other laboratory animals infected with S. mansoni, except that basophils participate in the inflammatory response observed in the skin and intestine.