Elimination of Biomphalaria pfeifferi, Bulinus tropicus and Lymnaea natalensis by the ampullarid snail, Marisa cornuarietis, in a man-made dam in northern Tanzania.

Marisa cornuarietis is a well known ampullarid competitor/predator of Biomphalaria glabrata in Puerto Rico. For the first time in Africa a flourishing population of Marisa has been established in a small, permanent, man-made dam at Kisangara, near Moshi, Tanzania. Prior to the release of M. cornuarietis in June 1977, this dam supported thriving populations of the pulmonate snail hosts Biomphalaria pfeifferi and Lymnaea natalensis; Bulinus tropicus and the melaniid Melanoides tuberculata were also common. Some 24 months after the establishment of Marisa the three pulmonate species had been eliminated; only M. tuberculata remained at about the same population density as originally recorded. Marisa has not caused any obvious adverse environmental impact in the dam. There is at present no valid evidence that this ampullarid would be a threat to local rice production, which is the only crop at risk, but carefully designed field trials should be undertaken to confirm or refute this view. In view of the vast number of permanent, lentic habitats throughout the Afrotropical region, which act as important transmission sites of schistosomiasis and fascioliasis, the role of Marisa cornuarietis as a cost-effective biological control agent in integrated control operations deserves henceforth to be energetically explored.

Patterns of partnership and condom use in two communities of female sex workers in Tanzania.

Two rapid ethnographic studies have found that commercial sex workers (CSWs) and other high-risk women in Tanzania have different categories of partners, ranging from single-time contacts to long and enduring relationships. Since the advent of HIV/AIDS prevention programs in Tanzania in the late 1980s, CSWs and their clients have been aware of the multiple benefits of condom use for the prevention of pregnancy and STDs including HIV. These women often use condoms for the single-time contact. However, since the HIV/AIDS epidemic, casual partners have decreased in number. These days, most of their sexual contacts occur within long-term partnerships, and within these relationships, condom use is rare. Although the message that condoms should be used during high-risk behavior has been largely accepted, the definition of a high-risk relationship needs to be extended from casual partnerships to include multiple long-term partnerships. In addition, men and women's empowerment through education, business, and equal rights needs to be addressed at all levels of society.