versão On-line ISSN 2078-5135
SAMJ, S. Afr. med. j. vol.100 no.12 Cape Town Dez. 2010
Schistosomiasis - an endemic but neglected tropical disease in Limpopo
To the Editor: After malaria, schistosomiasis is the second most prevalent tropical infection, but is first among the neglected tropical diseases (NTDs).1 Worldwide, an estimated 750 million people are at risk of schistosomiasis, and 200 million have the disease; 85% of the latter and all 20 million with severe disease are concentrated in Africa.2,3
We conducted a study that describes the pathology of biopsy diagnosed schistosomiasis, silent or symptomatic, in Limpopo Province to call attention on an NTD with potentially severe morbidity and mortality. This is especially important in view of the HIV/AIDS epidemic that poses a higher burden on women than men. Evidence is accumulating that female genital schistosomiasis (FGS) acts as a co-factor in the genesis of cervical pre-invasive and invasive lesions and/or as an entry point for the HI virus.
Over the period 2008-2009, all new cases of biopsy diagnosed schistosomiasis were prospectively recorded. The diagnosis was made in the presence of viable (embryonated) and/or non-viable (calcified) ova; Schistosoma haematobium in the presence of a terminal spike and S. mansoni if the spike was lateral.
The patients' age, gender, geographical origin, anatomical site and type of lesion, if any, were recorded. There were 266 females, and 45 males (F/M ratio 5.9/1). Table I illustrates the relative distribution by gender and affected organs. FGS accounted for 233 (87.6%) of the female cases; of the 127 cases involving the cervix, 29 (22.8%) were HIV-seropositive. Only 44 cases were asymptomatic, namely the incidentally found ova in bilateral tubal ligation (N=40) and prolapsed fibromyomas (N=4). In males, the appendix was the most common site - 30 (66.6%). The overall S. haematobium to S. mansoni ratio was 5.1/1. The ratio was 6.1/1 with urogenital pathology, and 3.2/1 with digestive tract pathology. These figures show an overlap of the two subtypes in urogenital and digestive lesions, and an overall predominance of S. haematobium. Of the cases of known geographical origin, 91% were from the northern and north-eastern parts of the province bordering Zimbabwe and Mozambique.
Failure in the supply of safe water sources and sanitation, and failure to control snail intermediate hosts, lead to the continued transmission of the infection.2,4 Control interventions require economic progress, political will and stability, and adequate public health structures and programmes.2 School-based health programmes are a major tool to reduce morbidity.5,6 South Africa is a signatory of World Health Assembly Resolution 54.19 that calls on member states to take effective steps to control schistosomiasis and soiltransmitted helminthiasis. This calls for non-selective treatment of all children at risk, and targets the year 2010 for regular chemotherapy programmes.6
The importance of such preventive policies is because praziquantel kills the adult schistosoma but not the ova. The ova cause granulomas, the entry and exit for the transmission of HIV, and possibly act as a co-factor in cervical carcinogenesis.3
Louis-Jacques van Bogaert
National Health Laboratory Service, and
University of Limpopo
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