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

Vaginal hirudiniasis from Dhaherah Province, Oman: With a note on internal hirudiniasis

A 75 years old lady from the Dhaherah Province, Oman, presented at Ibri Hospital, complaining from abnormal vaginal bleeding. Histopathological investigations of a cervical biopsy revealed no atypical features. A worm-like organism was removed from the vagina. Histocytological investigations of the organism revealed typical structures of a leech. The case was identified as vaginal hirudiniasis, probably due to Limnatis nilotica that necessitated a note on internal hirudiniasis

Comparative performance of parasitological and enzyme immunoassay tests in the diagnosis of intestinal protozoan infections

Diagnosis of Entamoeba histolytica, Giardia lamblia and Cryptosporidium parvum depends on microscopic detection of their cysts, trophozoites or oocysts in faeces. The aim of this study was to evaluate the use of three enzyme immunoassay [EIA] kits namely, Entamoeba CELISA, Giardia CELISA and Crypto CELISA [all from Cellabs diagnostic, Australia] in detecting the above mentioned intestinal protozoans. It was also aimed to compare the performance of these immunoassay kits with microscopy examination tests [direct faecal wet smears, formalin-ether concentration, Gomori's trichrome stain and auramine-phenol staining] routinely performed in the diagnostic Microbiology Laboratory at Sultan Qaboos University Hospital. A total of 571 stool specimens were examined. Giardia CELISA and Crypto CELISA were found to be more sensitive and specific than microscopy. The sensitivity of both kits was 100% and the specificity was 99% and 95% respectively. The performance of Entamoeba CELISA kit could not be established due to the small number of E. histolytica positive specimens. The enzyme immunoassay tests were easy to run and read compared to the cumbersome, insensitive and labour intensive parasitological tests. The enzyme immunoassays may not replace the parasitological tests but may be used to confirm the clinical diagnosis of these parasites

Usefulness of Kato-Katz and trichrome staining as diagnostic methods for parasitic infections in clinical laboratories

To assess the effi cacy of the Kato-Katz technique and to re-evaluate other routine procedures conducted in the Microbiology Clinical Laboratory at Sultan Qaboos University Hospital [SQUH] and to throw light on the prevalence of intestinal parasitic infections among a small group of food handlers in Muscat. Faecal samples collected from food handlers were examined using fi ve parasitological techniques. Out of 100 faecal samples, 53 were positive for one or more of 11 intestinal parasites. The Kato- Katz and trichrome stain methods were found superior to the other techniques in detecting helminthic and protozoan infections, respectively. The auramine stain was useful only in detecting Cryptosporidium parvum oocysts. A combination of trichrome stain and Kato-Katz techniques for stool examination is suffi cient and recommended for busy laboratories; auramine stain should be applied only to samples with suspected cryptosporidal infections