Data concerning the area, political divisions, topography, geology, meteorology, hydrography, and population of the Republic of El Salvador, Central America, have been assembled.
In a malaria survey 23,614 persons in 268 different localities were examined for splenomegaly and 11,354 blood preparations were made for detecting malaria parasites.
The provincial splenic indices varied from 9 to 35 per cent. For the country as a whole the index was 22.56 per cent.
Differences in the relative prevalence of each species of Plasmodium were not great.
The highest percentage of malaria-free villages corresponded to the zone situated at more than 900 meters altitude; whereas 90 per cent of the indices over 50 per cent were found in areas below 600 meters.
Spleen indices seemed to be unaffected by age, but the youngest children did have significantly higher blood parasite rates.
Ten localities were studied for their anopheline fauna and seven species were found.
The prevalence of A. albimanus varied inversely with altitude; just the reverse occurred with A. pseudopunctipennis.
A. albimanus was the only anopheline encountered infected with malaria parasites.
We have no evidence as yet that any other species acts as a natural vector of malaria in El Salvador.