Schistosomiasis is a parasitic disease caused by five species of the flatworm or blood flukes known as schistosomes. The disease affects over 200 million people and results in excess morbidity and mortality. Animal studies as well as human examples with pregnant women show that schistosomiasis can have dramatic negative effects on both mother and foetus.
Praziquantel is the drug of choice in treating schistosomiasis. However, current drug policies discriminate against the use of praziquantel for the treatment of schistosomiasis in women of child-bearing age. At the beginning of April 2002, an informal consultation took place in WHO, Geneva on the use of praziquantel in lactating and pregnant women.
A thorough review of the non-clinical toxicity and pharmaco-kinetics of praziquantel was presented, which concluded that the drug lacks significant toxic potential. Furthermore, although no systematic monitoring had been carried out, there was no indication of reproductive toxicity with inadvertent use in clinical practice. The WHO database held in the WHO Collaborating Centre for International Drug Monitoring contains only 208 adverse drug reaction reports for praziquantel none of which are related to reproductive toxicity.
Praziquantel in breast milk was also discussed. It was demonstrated that a suckling infant would ingest a maximum of 0.1% of the weight-adjusted maternal dose; this was regarded as safe.
Conclusions of the consultation may be summarised as follows:
1) Given the special schistosome related morbidity of women world wide, and the clear beneficial effect of praziquantel treatment,
a) women of child-bearing age should not be excluded from population based chemotherapy programmes for schistosomiasis
b) pre and post pubescent females should be included in all schistosomiasis control strategies and specific steps taken to guarantee their coverage.
2) All pregnant and lactating women infected with schistosomiasis should be offered immediate treatment.
3) All pregnant and lactating women living in areas highly endemic for schistosomiasis, where universal population chemotherapy is employed, should be included and offered treatment.
4) In schistosomiasis endemic areas where universal chemotherapy is not implemented, women of child-bearing age (including those pregnant and lactating) should be considered as a high-risk group for morbidity and targeted treatment should be offered to them.
5) WHO should encourage control programmes using praziquantel in pregnant women to collect data on the outcome of pregnancy for mother and infant in sufficiently large numbers. This data should be compared with the expected incidence of foetal abnormalities and other negative birth outcomes in the populations concerned.