World health report

Executive summary

Insect-borne diseases

WHO helped to fight malaria on many fronts in 1995. It established an interregional system for monitoring drug resistance in South-East Asia and the Western Pacific; supported research on such subjects as drug regimens and new diagnostic techniques; provided training for programme managers, specialists, district medical officers and community health workers; issued training materials; and assisted in control measures in refugee camps in Burundi, Rwanda, United Republic of Tanzania, and Zaire. WHO-led research enabled scientists to modify the genes of Plasmodium falciparum, the deadliest malaria parasite, opening up the possibility of developing new techniques for diagnosis and drug and vaccine development.

The only effective way to prevent dengue fever and dengue haemorrhagic fever is to eliminate the mosquito vectors or drastically reduce their numbers. The WHO control programme recommends selective, integrated vector control; active surveillance; emergency preparedness; capacity-building and training; and research on vector control. With WHO support, national control programmes have been developed in Indonesia, Myanmar and Thailand.

WHO participated in the implementation of the vaccination campaign that controlled the epidemic of jungle yellow fever in Peru in 1995, the largest outbreak recorded since 1950.

The Organization provided technical support and diagnostic reagents and assisted in vaccine procurement for the immunization strategy used to control Japanese encephalitis in endemic areas of India, Sri Lanka and Thailand.

New control tools and elimination strategies are being used in the fight against lymphatic filariasis (elephantiasis). Multicentre trials have shown that single-dose diethylcarbamazine, single-dose ivermectin, and especially combinations of the two drugs, are all effective and safe.

WHO set up a leishmaniasis surveillance network of 14 institutions worldwide, endorsed diagnostic guidelines and established a central epidemiological registry. The Organization cooperated with Sudan and Bangladesh in combating this disease. The results obtained from using insecticide-impregnated bednets in six countries are promising.

WHO prepared guidelines for the control of African trypanosomiasis (sleeping sickness) on behalf of Angola and Zaire, developed plans of action for several countries, and established a revolving fund for the supply of drugs to national programmes. Clinical trials are under way to ascertain whether shorter treatment schedules and lower dosages of pentamidine and melarsoprol may be just as effective as those currently used.

To combat onchocerciasis, the WHO, World Bank, UNDP and FAO joint Onchocerciasis Control Programme was launched in 1974. It has carried out vector control activities and distributed the drug ivermectin free of charge, curing 1.5 million people of the disease and opening up vast tracts of fertile land for resettlement and cultivation. The new African Programme for Onchocerciasis Control will continue to draw on the support of several United Nations agencies and nongovernmental organizations.

The campaign to eliminate Chagas disease from Argentina, Brazil, Bolivia, Chile, Paraguay and Uruguay is making good progress. House infestation rates have declined by 75%-98% in various affected areas.