The Manson Lecture Theatre at the London School of Hygiene and Tropical Medicine (LSHTM) was crowded on Wednesday 8th September 1995, with Society members and other interested parties, keen to hear Dr Sandy Cairncross of the LSHTM deliver the third annual Pumphandle Lecture, entitled “Turning the Worm”, on the Guinea Worm eradication programme.The Manson Lecture Theatre at the London School of Hygiene and Tropical Medicine (LSHTM) was crowded on Wednesday 8th September 1995, with Society members and other interested parties, keen to hear Dr Sandy Cairncross of the LSHTM deliver the third annual Pumphandle Lecture, entitled “Turning the Worm”, on the Guinea Worm eradication programme.
Dr Cairncross was a member of a UNICEF/WHO joint eradication team who worked in Ouagadougou between 1992 and 1995. The guinea worm is a “good” parasite in that it does not kill its host but nevertheless 0.5% of patients are handicapped for life and 30% have some degree of pain and suffering even after losing the worm. The economic consequences for regions where it is found are vast.
Larvae escape from infected humans into water where they are ingested by water fleas (Cyclops spp.). Humans who ingest an infected water flea in their drinking water are likely to become infected, the worm, which may reach two feet long maturing a year later ready to shed larvae. The whole life cycle outside humans therefore takes place in water, the only human parasite in which this is the case.
This parasite is widely distributed throughout central Africa and into central Asia. The slave trade led to its brief introduction into the Americas. The disease is seasonal. In the Sahel belt of Africa cases peak in the rainy season, but in forest areas, where water is always present, it peaks in the dry season. Its seasonality and lack of annual vector mean that eradication programmes can be targeted at that time of year.
No vaccine has been developed against the disease; eradication programmes are aimed either at the vector or the human host. Two major methods have been used:
Insecticidal treatment aimed at the vector. Insecticides such as Temephos, which are harmless to humans, are effective against Cyclops and can provide effective cover at a local level. However, the costs of staff, equipment and insecticide for treatment of large areas is prohibitive.
Production of safe water. This has two components, the first involving educating infected persons not to go into water – and hence not transmit the larvae; and the second the provision of simple water filter to remove Cyclops from drinking water and break the chain of transmission.
These measures, particularly the latter, combined with a detailed community based surveillance programme have proved successful in reducing the incidence of the disease. A valuable sideline of the eradication programme, which trains local people to undertake the work, has been that the availability of these trained personnel has had an impact on other diseases and has improved local health care.
Dr Stanwell-Smith gave the vote of thanks after which the meeting was formally brought to an end by the ceremonial removal of the handle of the society’s pump. A large group then moved to the John Snow pub in Broadwick Street, Soho, for the customary toast to Snow’s name, examination and signing of the visitor’s book.