Epidemiology and control of human schistosomiasis in Tanzania

Abstract

In Tanzania, the first cases of schistosomiasis were reported in the early 19th century. Since then, various studies have reported prevalences of up to 100% in some areas. However, for many years, there have been no sustainable control programmes and systematic data from observational and control studies are very limited in the public domain. To cover that gap, the present article reviews the epidemiology, malacology, morbidity, and the milestones the country has made in efforts to control schistosomiasis and discusses future control approaches. The available evidence indicates that, both urinary and intestinal schistosomiasis are still highly endemic in Tanzania and cause significant morbidity.Mass drug administration using praziquantel, currently used as a key intervention measure, has not been successful in decreasing prevalence of infection. There is therefore an urgent need to revise the current approach for the successful control of the disease. Clearly, these need to be integrated control measures.

Figure 1

Distribution of schistosomiasis (both S. mansoni and S. haematobium ) in Tanzania: Maximum point prevalence of schistosomes infection and location of S. mansoni and S. haematobium surveys in the United Republic of Tanzania.

Figure 2

Active water contact activities such as fishing, fetching water direct from the lake and agriculture along the lake basin increases the risk of S. mansoni transmission on the southern shore of the Lake Victoria, north-western Tanzania.

Figure 3

Arrows showing eggs of S. mansoni (with lateral spine) in the submucosa and mucosa of the ileum and caecum of a 7 year old Tanzania boy presenting with intestinal.

Figure 4

Arrows showing eggs of S. haematobium in the urinary bladder wall of a 40 year old male reported at the Bugando Medical Center, north-western Tanzania with a chief complaint of genital mass and frequent micturitions. Histological (H &E) examination of urinary bladder biopsy revealed co-infections of urinary bladder cancer and S. haematobium eggs in the wall of the bladder and fibrosis.