Worm Development in Hamsters Infected with Unisex and Cross-Mated Schistosoma mansoni and Schistosoma haematobium

Abstract

Schistosoma mansoni and Schistosoma haematobium coexist in Egypt and in other areas in Africa, and people frequently are infected with parasites of both species. The effects of the interactions between worms of both sexes of the 2 species on development and egg laying were evaluated in vivo by infecting hamsters with cercariae from Biomphalaria alexandrina and Bulinus truncatus snails infected with single miracidia. In hamsters with unisex infections, male worms of both species were small. Schistosoma mansoni females were stunted and partially mature but did not contain eggs. Schistosoma haematobium females, though stunted, sometimes contained and laid small eggs, which were deposited in the liver, but few of which contained motile embryos. This suggests that unisexual infection with S. haematobium female worms produces a risk for liver damage due to egg deposition in tissues. Both S. mansoni and S. haematobium females that mated with males of the heterologous species were significantly larger than females from unisexual infections; they were sexually mature and possessed eggs in the uterus. The eggs in the liver homogenates of cross-specific infected hamsters contained fully developed miracidia that hatched in filtered pond water.

A new description of the reproductive system of Schistosoma mansoni (Trematoda: Schistosomatidae) analyzed by confocal laser scanning microscopy

“…However, occasionally some differentiated vitelline cells were developed and even some malformed eggs with shells were found, despite the complete absence of males (Shaw and Erasmus 1981). Virgin females that grow up in the absence of males differ considerably in size from those recovered from mixed infections in which they are coupled (Khalil and Mansour 1995;Kunz 2001).…”

“…Specimens grown in the absence of the other gender are smaller than those from mixed infections (Khalil and Mansour 1995;Kunz 2001). Females have an undeveloped reproductive system with a poorly developed Mehlis' gland, an ovary in which the Golgi complexes do not produce typical cortical granules, and vitteline cells which remain immature (Erasmus 1973).…”

Schistosome Satellite DNA Encodes Active Hammerhead Ribozymes

“…Horizontal transmission between organisms in the same host, however, may be possible. In the laboratory, cross-mating can readily be accomplished between S. haematobium and S. mansoni when they share a hamster host (22). These two species also coparasitize their human hosts in Africa.…”

Microarray analysis of gene expression induced by sexual contact in Schistosoma mansoni

“…Nevertheless, some studies show that male S. mansoni and S. haematobium worms from single-sex infections are significantly smaller and have a reduction in the number of testes when compared to worms from homologous paired infections [24,25]. Using the data published by Basch and Gupta it is possible to observe that pairing also stimulates a higher rate of cell division (as measured by the number of nuclei per section unit area) in males when bisexually paired males and unisexual unpaired males are compared [26].…”