Survey of bovine trypanosomosis in the Kachia Grazing Reserve, Kaduna State, Nigeria.

This study assessed the prevalence of trypanosomes in cattle at the Kachia Grazing Reserve (KGR) in March and June 2004 and in February 2005. A total of 1293 cattle blood samples were collected at random. The samples were analysed using the buffy coat technique and Giemsa thin blood films for parasite detection and identification. The effects of herd pen location to watering and grazing point's distances (using the global positioning system (GPS)) were determined and mean Packed cell volume (PCV) assessed. Overall, the detected prevalence of trypanosomosis was 8.4%, much higher than the previous prevalence of 5.3% before the present study was conducted. The prevalences in the months of March, June (2004) and February (2005) were 2.3%, 11.6% and 15.4%, respectively. Increased prevalence was associated with proximity of herd pens to watering point's distances (chi(2) for linear trend=4.447, P<0.05), but no association of herd pens to grazing point distances (chi(2)=2.186, P>0.05); suggesting that hydrological network played an important part in trypanosomosis transmission. The mean PCV of parasitaemic and apparasitaemic cattle were respectively 25.99+/-1.82% and 29.31+/-1.70%. The drop in mean PCV was most in 0-1-year age group, 23.47+/-3.10% and was statistically significant (P<0.05), suggesting that anaemia was most pronounced in this age group. Factors that may have contributed to the increased prevalence obtained were collapse of control measures and breed susceptibility. Since, Zebu cattle were the predominant breeds in the reserve, the study advocates effective use of insecticide impregnated screens (traps and targets) with community participation in mind for sustainability. If government intervenes through PATTEC ground spraying of insecticides in the reserve is recommended. In addition, chemotherapeutic and chemoprophylaxis should be systematically used to fight the problem of trypanosomosis in the KGR towards improved livestock production.

Analysis of IgG isotype responses against Onchocerca volvulus antigens in children in an onchocerciasis-endemic area in northern Nigeria.

This study evaluated the usefulness of parasite-specific IgG and IgG isotype responses for diagnosing early or pre-patent onchocerciasis in children using sandwich ELISA. The children (n = 199) were aged between 5 and 12 years and living in a meso-endemic area of northern Nigeria. Only five had detectable skin microfilariae. The mean optical density (OD) values of children from the study area were significantly higher than those of normal controls' sera (n = 10, p < 0.01), except for IgG2. There were 145 (73%) children positive for total IgG, 161 (81%) for IgG1, 68 (34%) for IgG3 and 187 (94%) for IgG4 antibodies. The mean OD values of all antibodies tended to increase with age and peaked in the 9-10-year age group, except in the case of IgG3 which peaked at 11-12 years. IgG4 proved most sensitive compared with IgG, IgG1 and IgG3 in all age groups, and was significantly different (p < 0.05). Analysis by sex showed no significant difference between the boys and girls. We conclude that IgG4 serology is a useful diagnostic tool in the assay of early or pre-patent onchocerciasis in children.

Analysis of Plasmodium falciparum infections in a village community in Northern Nigeria: determination of msp2 genotypes and parasite-specific IgG responses.

The genetic diversity of P. falciparum and multiplicity of infection has been studied in a village in Northern Nigeria at the end of the rainy season, when transmission is high. We analysed blood samples from 104 individuals aged 5-70 years by polymerase chain reaction (PCR) amplifying the gene for the merozoite surface protein MSP2 followed by genotyping based on restriction fragment length polymorphism (RFLP). 94.2% of all samples were parasite positive by PCR and over 80% of those had multiple infections. The age distribution of the average number of parasite clones present in P. falciparum infections showed an initial increase, then reached a peak multiplicity in children 8-10 years of age, and afterwards decreased significantly with age. Mean multiplicity in those 8-10-year-old children was 5.4 clones per carrier. Peak multiplicity and parasite diversity in Nigerian individuals is compared to findings from other study sites in Africa and PNG. The prevalence of IgG antibodies against the circumsporozoite protein (CSP), an indicator for malaria exposure, was over 85% in all age groups showing a high exposure of villagers to P. falciparum. OD values in ELISA were positively correlated with age. There was no correlation between the level of IgG against CSP and the multiplicity of P. falciparum infections determined by PCR of msp2. These results imply that in highly endemic areas multiplicity of infection is not directly correlated with exposure to P. falciparum.