The effects of quarry mining on the epidemiology of Schistosoma haematobium in schoolchildren, in Ishiagu, south-eastern Nigeria

Over the last two decades there has been a noticeable increase in the activities of quarry-mining companies in the Ishiagu area of south-eastern Nigeria. These activities have produced an ever-growing number of abandoned quarry pits that usually quickly fill with water and appear to become suitable habitats for the freshwater snails that may act as intermediate hosts of Schistosoma haematobium. To examine the potential role of quarry mining on the prevalence of urinary schistosomiasis caused by S. haematobium, urine samples were collected from 1819 schoolchildren in northern Ishiagu (an area with intense mining activities and many quarry pits) and from 252 schoolchildren in southern Ishiagu (an area with no mining activity or quarry pits). When these 2071 samples were checked for schistosome eggs, 1005 (48.5%) were found positive and 252 (25.1%) of the infected children showed visible haematuria. The children from northern Ishiagu were much more likely to be infected than the children from the south (53.3% v. 13.9%; P < 0.001). Curiously, only the children from northern Ishiagu showed a gender-related difference in prevalence that was statistically significant, with boys more likely to be infected than girls (60.9% v. 38.5%; P < 0.001). Although the 'children' investigated varied in age from 5 to 20 years, no statistically significant increase or decrease in prevalence with age was apparent. Four species of snails (Bulinus globosus, B. rohlfsi, B. forskalii and B. senegalensis) were found in the overall study area but B. globosus was only found in the quarry pits in northern Ishiagu and never in the water bodies of southern Ishiagu. It does appear that quarry-mining activity in the Ishiagu area is a factor in the local epidemiology of urinary schistosomiasis, with the water bodies that form in the abandoned quarry pits serving as the principal foci of transmission.

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