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Schistosomiasis in Mauritius

1953; Oxford University Press; Volume: 47; Issue: 6 Linguagem: Inglês

10.1016/s0035-9203(53)80010-6

1878-3503

S. G. Cowper,

Global Maternal and Child Health

Summary In the course of a survey of schistosomiasis (S. haematobium only) in Mauritius, this infection was found to be widespread throughout large areas of the island. The most heavily infected regions are the Port Louis-Pamplemousses area, an area round Argy and an area in the south centering round Carreau Accacias (Grand Port). The part of the island lying north of the Port Louis-Argy-Flacq line is more heavily infected than the rest but there is also a good deal of infection in the built-up areas of Plaines Wilhems with a possible source of infection in Rose Hill. The city of Port Louis is dealt with in some detail. The infection rate in the northern half of the city is significantly higher than in the southern half. It is believed that the River Latanier and various streams and irrigation channels in the Ste. Croix (Père Laval) area are a principal source of infection. In a survey of 50 schools extending throughout the island an infection rate above 50 per cent. was found in two schools, above 25 per cent, in eight and above 10 per cent. in 15 schools. Full details are presented in a table. No significant seasonal incidence in cases recorded in the laboratory routine was noted, but there is some evidence that transmission corresponds with the hot wet season (December to April). The sex incidence showed that about twice as many males as females are infected (all ages). Age-groups indicated that the disease is uncommon in infants below 5 years and in the middle-aged, while incidence is highest in school children, adolescents and young adults. There is no indication of any racial immunity or susceptibility, the predominance of infection among Indians and Creoles being certainly occupational. In a series of experiments the local strain of S. haematobium was passed through Bulinus (Pyrgophysa) forskali Erhenberg, cercariae were shed, mice infected, and adult worms and ova recovered. This confirms the previous experimental work of Adams (1934–35). A description of this snail is given. All experiments with other molluscs were negative. The epidemiological evidence in favour of B. forskali as the only natural vector is considered and found to be conflicting. While a second vector cannot be absolutely ruled out, B. forskali should certainly be considered the presumptive vector. No natural wild infection has yet been discovered. Part of the literature dealing with B. forskali as a suspect is summarized. This species has not been definitely incriminated outside Mauritius so far as the writer can ascertain. An attempt to use the cercarial antigen skin test for screening and diagnosis is described. Reasons are given for rejecting this test as locally unreliable.