Epidemiological stratification of malaria in Comoro archipelago, Indian Ocean.

In the Comoros Islands, the level of malarial endemicity varies greatly fro m one island to the other; even though the total area (4 islands) covers le ss than 2 300 km(2) and has a population of some 600 000 people only. The epidemiological stratification is based on the diversity of human and p hysical characterisation. They both determine the presence and the behaviou r as well as the size of the vector's populations. Vectorial dynamics can e xplain varying levels of endemicity given parasitological indicators and sp ecific morbidity. Analysising these criteria shows up different epidemiolog ical features and serves as a basic guideline for malaria control. The effi ciency of this control depends on the relationships between the intensity a nd the length of the transmission, in the framework of protection mechanism s; it is of crucial importance for clinical treatment Further elements are the age of the patient, the season and the geographic situation of the area . Stratification provides explanations for these relationships and helps to d efine antimalarial programmes adapting to each situation a range of therape utic and antivectorial methods. The availability and accessibility of anti-malarial medicine is the minimum requirement for reducing mortality domestic spray insecticides for reducin g transmission are effective for several years and should be followed by th e use of mosquito nets or curtains impregnated with pyrethrinoids, and in t he particular case of Grande Comore, the use of larvivorous fish. As anywhere else the economic development, which is dependent on political stability is the essential basis for malaria control.