The schistosomiasis problem in Nigeria

Schistosomiasis is endemic in Nigeria as revealed by several prevalence studies but the degree of endemicity is low. The proliferation of several irrigation projects all over the country has stabilized the infection in Northern Nigeria while in the West rapid urbanisation, supply of portable water and mass chemotherapy have combined to reduce the prevalence rates. Human infection is measured by the determination of incidence, prevalence and intensity of infection. Heavy infections can rapidly be detected by use of urinalysis reagent strips to measure haematuria and protein levels in urine. The prevalence of severe pathological forms of the disease is very low and schistosomiasis is not associated with bacteriuria or hypertension in Nigeria, although isolated cases of ectopic lesions of the genitalis and uterus have been reported. Nodular filling defects occur early during infection, while bladder calcification comes at a later stage. The severity of the disease is related to the intensity of infection. Clinical trials with metrifonate and niridazole among other drugs have been carried out, with varying results. A new drug, praziquantel has been assessed and found suitable for mass use. Three methods of control include adequate provision of safe water, selective or targeted mass chemotherapy and use of molluscicides to kill the snails. Each method has its advantages and drawbacks, but the therapeutic approach is cheap, effects quicker result and treats the infected patients.