An assessment of the replicability of a standard and modified sanitary risk protocol for groundwater sources in Greater Accra.

Sanitary risk inspection, the systematic observation of contamination hazards, is often used to manage safety of water sources such as wells and boreholes. However, the replicability of sanitary risk inspections undertaken by different observers has not been studied. This study aimed to assess the replicability of sanitary risk inspections by two different observers in urban and peri-urban neighbourhoods of Greater Accra, Ghana. Two observers independently used a standard protocol to record contamination hazards around 62 groundwater sources, additionally recording urban-specific hazards such as damaged sewage pipes via a modified protocol. We calculated risk scores as the proportion of hazards observed at each source, separately for each observer. Linn's concordance correlation coefficient indicated very high agreement between the two observers' risk scores (n = 62; c = 0.949, 95% confidence limits 0.917-0.968). However, risk scores from urban-specific observations were uncorrelated with those from the standard protocol (r = 0.11, p = 0.41 for observer 1; r = 0.16, p = 0.22 for observer 2). Ours is the first study of replicability of sanitary risk observations and suggests high inter-observer agreement. However, urban contamination hazards were not captured using the standard protocol. In the future, assessment of inter-observer agreement and observations of urban-specific hazards could be incorporated into nationwide or regional sanitary risk surveys.

Sachet water quality and product registration: a cross-sectional study in Accra, Ghana.

The study's objectives were to assess the extent to which packaged water producers follow product registration procedures and to assess the relationship between product registration and drinking water quality in Accra, Ghana. Following preliminary analysis of a national water quality survey, 118 packaged sachet water samples were collected by sampling all brands sold by 66 vendors. A sample of vendors was selected from two high-income and two low-income areas of Accra, Ghana. Sachet packaging and labelling details were recorded and compared to a regulatory database to assess product registration. All samples were weighed and tested for faecal indicator bacteria and selected physico-chemical parameters. Product registration numbers and brand names could be matched to regulatory records for 77 of 118 sachets (65.2%). All samples tested were compliant with national water quality standards for faecal indicator bacteria and nitrate. Brand registration was not associated with any of the quality indicators considered. The results of this study suggest that while a substantial proportion of sachet water is sold without formal product registration, the microbial quality of the unlicensed water is consistently high in Accra, Ghana. Further examination of regulatory enforcement and monitoring will be needed to ensure sustained high water quality over time.

Associations between frequencies of a susceptible TNF-alpha promoter allele and protective alpha-thalassaemias and malaria parasite incidence in Vanuatu.

Tumour necrosis factor-alpha (TNF-alpha) is one of the key cytokines that influence the pathology of microbial infections. The genetic susceptibility to severe forms of falciparum malaria is differentially associated with TNF-alpha promoter gene polymorphisms (TNFP alleles). In a previous study, we identified a TNFP-allele characterized by a C to T transition at position -857 (TNFP-D allele) as a marker for susceptibility to cerebral malaria in Myanmar. The frequencies of TNFP alleles on six islands of Vanuatu, Melanesia (South-west Pacific) were estimated to investigate whether malaria selection pressure on this susceptibility marker has influenced its prevalence. Within the archipelago of Vanuatu there is a decreasing cline of parasite incidence from North to South. Of the four alleles of the TNFP gene detected in Vanuatu, the TNFP-D allele frequencies were inversely correlated with the parasite incidence of islands; TNFP-D varied from 0.55 on the island with the lowest parasite incidence to 0.26 on the island with the highest parasite incidence (r = -0.855, P = 0.03). We also observed a significant correlation between the frequencies of alpha-thalassaemia alleles, thought to protect against malaria and parasite incidence in the same populations. These data are consistent with a previously reported correspondence between the frequencies of glucose 6-phosphate dehydrogenase (G6PD) deficiency and parasite incidences on the islands of Vanuatu (Kaneko et al. 1998) and indicate that the degree of malaria endemicity has influenced the allele frequencies of at least three loci that confer both susceptibility (TNFP-D) and protection (alpha-thalassaemias and G6PD deficiency).

Bancroftian filariasis in an irrigation project community in southern Ghana.

An epidemiological study to document the endemicity and transmission characteristics of bancroftian filariasis was conducted in an irrigation project community in southern Ghana. In a 50% random sample of the population, the prevalence of microfilaraemia was 26.4% and the geometric mean microfilarial intensity among positives was 819 microfilariae/ml of blood. Hydrocoele was found in 13.8% of the males aged > or =18 years, and 1.4% of the residents examined, all females, had tymphoedema/elephantiasis. Detailed monitoring of the microfilarial intensity in 8 individuals over a 24-h period confirmed its nocturnal periodicity with a peak at approximately 0100 hours. The most important vector was Anopheles gambiae s.l., followed by An. funestus. The abundance of these mosquitoes and their relative importance as vectors varied considerably between the wet and the dry season. Opening of the irrigation canals late in the dry season resulted in a remarkable increase in the population of An. gambiae (8.3% of which carried infective filarial larvae) to levels comparable to those seen during the wet season, suggesting that the irrigation project is responsible for increased transmission of lymphatic filariasis in the community.