Intestinal protozoa and intestinal helminthic infections among schoolchildren in El dhayga, Central Sudan

A cross-sectional study was carried- out to determine the prevalence of intestinal parasitic infections and soil-transmitted helminths [STHs] among primary schoolchildren in El dhayga, Central Sudan. In total, 142 [90.4%] of 157 children harboured at least one type of intestinal parasite. Ascaris lumbricoides, Hymenolepis nana, Entamoeba histolytica and Giardia lamblia were the most common parasites found, with prevalence rates of 32.5%, 30.6%, 33.1 and 19.7%, respectively. Out of these 157, 29[18.5%] children harboured >/= two intestinal parasitic infections. No cases of Schistosoma mansoni or Enterobius vermicularis were identified. Thus, our study demonstrates significant burden of intestinal protozoa and STH infections in this part of Sudan and highlights the need for preventive and intervention measures

Laboratory studies on the prevalence and cercarial rhythms of trematodes from Bulinus truncatus and Biomphalaria pfeifferi snails from Khartoum state, Sudan

[a] To determine the natural infection rate of Bulinus truncatus and Biomphalaria pfeifferi snails with trematodes' cercariae. [b] To determine the emergence and rhythmicity of cercariae. [c] To elucidate the high-risk time for man and other animals to acquire infection. Snails were collected from Dawar El Mahadi Agricultural Scheme, Khartoum State, identified in the laboratory, kept at room temperature and fed on lettuce. The snails were screened weekly for six weeks for natural infection and infected snails were kept in the dark. The swimming patterns and resting position of the freshly emerged cercariae were studied using a stereomicroscope. The rhythmicity of the different types of cercariae was studied by screening three sets of 5 naturally infected snails under fluorescent light from 07.00 to 19.00 and similar sets from 19.00 to 07.00. Out of 1,257 screened Bulinus truncatus, 187 [14.9%] shed four types of cercariae. The highest prevalence of natural infection [9.5%] was by schistosome cercariae followed by amphistome [2.5%], xiphidiocercariae [2.4%] and lastly by avian cercariae [0.5%]. However, out of 200 screened B. pfeifferi, 22 [11%] shed only xiphidiocercariae. The rhythmicity studies showed that the emergence of schistosome cercariae increased steadily from 07.00 to reach its peak at 11.00-13.00. The emergence rhythms of avian cercariae are similar to those of the schistosome, but with an early peak at 09.00-11.00. The xiphidiocercariae and amphistome cercariae started with high rate of emergence at 07.00. and decreased gradually to very low levels or complete disappearance, respectively, around sunset. Information on cercarial rhythmicity and chronobiological characteristics are thought to be useful in avoiding water contact during high-risk time of infection and may be helpful in the identification of closely related species and strains of cercariae