The sero-prevalence of T. gondii infection in this study was lower than that reported in Dar es Salaam, Tanzania two decades ago in which more than 35% of the pregnant women had evidence of T. gondii infections [7, 8]. The difference could partly be explained by the geographical variation; Dar es Salaam is hotter than Mwanza and hotter weather has been found to favour sporulation of oocysts; secondly the difference could be due to the diagnostic methods, a study in Dar es Salaam used an immunosorbent agglutination assay while in the current study a highly specific ELISA method was used. However, the variation of sero-prevalence within a given country is not a new phenomenon; in USA the seroprevalence was found to vary from 17.5% in the west to 20.5% and 29.2% in the south-midwest and north-east, respectively . Also the sero-prevalence in this study was low compared to studies in Brazil , Saudi Arabia , Morocco  and Sudan . This may be accounted for by differences in climatic conditions, as reported before, where higher sero-prevalence is associated with hotter and wetter areas, which is favourable for sporulation of oocysts compared to less humid areas [14, 15].
An increase in sero-positivity of anti-T. gondii antibodies was observed with increasing age in this study, which is consistent with other studies [6, 16]. The observed risk increase per year might be considered high and may reflect higher infection risks at early adolescence. In this study, business women and employed pregnant women had higher infection rates with T. gondii than peasants, in contrary to other studies [6, 17]. This may partly be explained by the economic status of the pregnant women in which more employed and business women, who have a high income compared to peasants; also tend to live in towns and can afford to eat poultry and pork which have been found to be a major source for T. gondii transmission [17, 18]. This observation is further supported by the fact that, in this study, as it was observed in China ; residents from urban areas were more infected with T. gondii than those from rural areas.
Contaminated fruits and eating undercooked meat has been reported as a potential source of T. gondii infection [18, 20–22]. Drinking contaminated water is another source of T. gondii infection [23, 24]. A study done in Zaria, Nigeria documented a high sero-prevalence rate among pregnant women who drunk water from the well , this was not the case in the recent study done in Mexico  and in the present study. Contact with cat litter may pose another risk for T. gondii infection. However, in this study no significant association between T. gondii infection and a history of cat contact was found. The findings are consistent with studies done in Palestine , Turkey  and Nigeria . Nevertheless, studies from Taiwan  and Ethiopia  showed a significant association between contact with cats and sero-prevalence of T. gondii. However, the risk of contracting T. gondii infection is not just the mere contact with cats but the way the cats’ litter is handled.