Chickens and pigs as transport hosts forAscaris,TrichurisandOesophagostomumeggs

Abstract

Ten chickens and 2 pigs were fed non-embryonated eggs ofAscaris suum,Trichuris suisandOesophagostomum dentatum. Each chicken was fed approximately 15000 eggs of each parasite species while approximately 300000 eggs were given to each of the pigs. After passage in chickens 8.3% ofO. dentatumeggs were recovered in faeces compared to 61.1% and 41.6% ofA. suumandT. suiseggs, respectively. After passage in pigs the percentages were 38.4%, 49.1% and 30.3%, respectively. After embryonation in the laboratory, 1000 eggs of each parasite species having passed through chickens or pigs or having been kept in the laboratory as controls were fed to groups of 6 pigs to check the infectivity. The number ofA. suumrecovered from pigs was similar in the 3 groups with 34.0, 52.8 and 41.8%, respectively. The recovery ofT. suisin the pig passage group was 54.0% which was significantly lower than the recovery in the chicken passage group (81.8%) and the laboratory group (88.0%). The number ofO. dentatumrecovered was not significantly different among the 3 experimental groups, the percentage recovery being 30.5, 9.2 and 28.5%, respectively. One explanation for the lower infectivity ofT. suisin the pig passage group may be that the eggs have been sublethally damaged through their passage. The results demonstrate that chickens and pigs can act as transport hosts forA. suum, T. suisandO. dentatum, and it is highly probable that these domestic animals are able to act also as transport hosts for the human parasite equivalents. This will have important consequences for the environmental and behavioural strategies in human helminth control programmes.