Prevalence of Giardia in dairy cattle in Lusaka and Chilanga districts, Zambia.

Giardia is an intestinal protozoan parasite of mammals including humans. A cross-sectional study was conducted to estimate prevalence of Giardia infections in smallholder and commercial dairy herds in Chilanga and Lusaka districts of Zambia. A total of 377 calves aged from 1 to 365 days were sampled on 34 farms. All faecal samples were analyzed for Giardia antigen using a commercially available ELISA kit. Overall prevalence of Giardia was 34.5% (95% CI=29.7-39.3). Among smallholder farms, animal level prevalence ranged from 0 to 100% (mean=44.6±36.9 standard deviations) and 12.5 to 60.9% (mean=33.5±16.7 standard deviations) within commercial herds. Prevalence was highest in calves less than three months old (p=0.010), and there was no significant difference in the prevalence between smallholder and commercial farms (p=0.300). Giardia prevalence was not associated with occurrence of diarrhoea in the calves (p=0.205). The study demonstrates that Giardia infections are common in dairy herds in the study areas, especially in calves less than three months of age.

Seasonal prevalence and incidence of Cryptosporidium spp. and Giardia duodenalis and associated diarrhoea in children attending pre-school in Kafue, Zambia.

Prevalence, incidence and seasonal variation of Cryptosporidium and Giardia duodenalis were studied over a 12-month period in 100 children from four pre-schools in Kafue, Zambia. Questionnaire data and a single stool sample were collected monthly from each child. Samples were processed using a commercial kit (Meridian Diagnostics Inc., USA) and oo(cysts) visualised by immunofluorescence microscopy. Cryptosporidium was detected in 30.7% (241/786; 95% CI = 27.5-33.9) while G. duodenalis was detected in 29.0% (228/786; 95% CI = 25.8-32.2). A total of 86% experienced one or more episodes of cryptosporidiosis while 75% had giardiasis. Cumulative incidence per 100 children was 75.4 for Cryptosporidium and 49.0 for G. duodenalis. Both infections were significantly more common in the wet compared to the dry season (34.8%, 162/466 vs. 24.7%, 79/320, P = 0.003 and 35.2%, 164/466 vs. 20.0%, 64/320, P < 0.001, respectively). Thus, risk ratios (RR) were 1.41 (95% CI = 1.13-1.77) and 1.76 (95% CI = 1.38-2.27) for Cryptosporidium and Giardia, respectively. Diarrhoea was significantly associated with cryptosporidiosis (RR = 1.23, 95% CI = 1.03-1.47; P = 0.029) but not with giardiasis (RR = 1.12, 95% CI = 0.91-1.53; P = 0.26). We conclude that gastro-intestinal protozoal infections are highly prevalent among children attending pre-school in peri-urban Zambia highlighting the need for further studies of risk factors.

Development of PCR/dot blot assay for specific detection and differentiation of taeniid cestode eggs in canids.

We report the development of a colourimetric PCR/dot blot assay targeting the mitochondrial gene NADH dehydrogenase subunit 1 (nad1) for differential diagnosis of taeniid eggs. Partial sequences of the cestode nad1 gene were aligned and new primers were designed based on conserved regions. Species-specific oligonucleotide probes (S-SONP) for canine taeniid cestodes were then designed manually based on the variable region between the conserved primers. Specifically, S-SONP were designed for the Taenia crassiceps, T. hydatigena, T. multiceps, T. ovis, T. taeniaeformis, Echinococcus granulosus (genotype 1), E. multilocularis and E. vogeli. Each probe showed high specificity as no cross-hybridisation with any amplified nad1 fragment was observed. We evaluated the assay using 49 taeniid egg-positive samples collected from dogs in Zambia. DNA from 5 to 10 eggs was extracted in each sample. Using the PCR/dot blot assay, the probes successfully detected PCR products from T. hydatigena in 42 samples, T. multiceps in 3 samples, and both species (mixed infection) in the remaining 4 samples. The results indicate that the PCR/dot blot assay is a reliable alternative for differential diagnosis of taeniid eggs in faecal samples.

Intestinal helminths and protozoa in children in pre-schools in Kafue district, Zambia.

Intestinal parasitic infections are among the most widespread of human infections in developing countries, and children are the most vulnerable. The aim of this study was to determine the prevalence of the protozoa Cryptosporidium and Giardia, as well as prevalence and intensity of intestinal helminths in children attending pre-school or day-care centres in Kafue District, Zambia. Single stool samples were collected from 403 children from 10 pre-schools and were subjected to duplicate Kato-Katz thick smears to identify and quantify helminths. A commercial immunofluorescence kit was used to identify Cryptosporidium- and Giardia-positive samples. The overall prevalence of helminth infection was 17.9%. Ascarislumbricoides was found in 12.0%, hookworm in 8.3%, Taenia spp. in 0.9%, Hymenolepisnana in 0.6% and Schistosomamansoni in 0.3%. The overall prevalence of Cryptosporidium and Giardia was 28.0 and 29.0%, respectively, with more girls infected with Giardia (33.8%) than boys (22.7%) (P=0.02). Significant differences in infections with A. lumbricoides and Cryptosporidium were observed between the various pre-schools (P < 0.001). These findings indicate that intestinal parasites are prevalent in children enrolled in pre-schools in Zambia. Future studies should explore local factors associated with transmission of these infections, and consequently provide the necessary health education to parents and teachers.

Asymptomatic cryptosporidiosis in Zambian dairy farm workers and their household members.

The prevalence of Cryptosporidium and the possibility of zoonotic transmission on dairy farms were examined. Eighteen cases of cryptosporidiosis (prevalence 6%) were identified in 82 farm workers and 207 household members. Furthermore, 70 (34%) of 207 calf samples were positive. Based on the 70kDa heat shock protein and the 18S rDNA gene, Cryptosporidium parvum was identified in 75% of the positive farm workers and in 60% of the household members. Of the positive calves, 62% were infected with C. parvum, indicating a possible zoonotic transmission on these farms.