Mass migrations of non-immune populations into endemic areas for political reasons further complicates matters. From the early 1970's the malaria situation has slowly and progressively deteriorated, and reduced control measures between 1972 and 1976 due to financial constraints lead to a massive 2-3 fold increases in cases globally. Spraying never truly eradicated the mosquitoes anywhere, and the reduction in the more persistent P.vivax infections were much less than for P.falciparum - though the latter returned in much greater strength as control measures waned. The growing interchange of populations between malarious countries and malaria free countries is responsible for the continuous increase in the number of imported malaria cases in European countries, and causes serious concern because of possible epidemic focal resurgence in receptive areas such as the Mediterranean. Since 1976, several new pockets of malaria transmission have evolved, and a WHO 1980 report recommended that countries which had become non-malarious should maintain at least one malaria vigilance unit.
Malaria is generally endemic in the tropics, with extensions into the subtropics.
Distribution varies greatly from country to country, and within the counties themselves, as the flight range of the vector from a suitable habitat is fortunately limited to a maximum of 2 miles, not taking account of prevailing wind etc. Current data for Africa is unavailable. The disease is endemic in 91 countries currently, with small pockets of transmission in a further eight. P.falciparum is the predominant species, with 120,000,000 new cases and up to 1,000,000 deaths per year globally. It is the P.falciparum species which has given rise to the formidable drug resistant strains emerging in Asia.