Current status of malaria in Taiwan from 1966 to 1990

Malaria was highly or moderately endemic in about 200 townships among the 360 municipalities in Taiwan before the World War II. During and after the War, annual incidence of malaria was estimated as 1.2 million cases out of 6 million population at that period. In 1952, malaria mortality was reported as 27.5 per 100,000 persons. Malaria Eradication Program in Taiwan was successfully carried out during 1947-1965 through a combined effort made by the Government, WHO, UNICEF and USAID, and by the participation of the community. Since 1966, avoidance of malaria transmission in population centers has been well maintained through the network of malaria surveillance system, both parasitological and entomological, at the ports (sea and air) of entry and by the 383 public health services all over the island. Through this surveillance network, a total of 936 malaria cases and distribution of the vector mosquito Anopheles minimus have been well documented during 1966- June 1990. Of the 936 malaria cases detected, 819 cases were classified as imported from outside the country, 14 cases as relapsing, 17 cases as induced infection through blood transfusion, and 86 cases as the secondary infection originating from the imported cases. These 86 cases were exclusively P. vivax infections which were found concealed in the mountainous area of the northern most of Taiwan during 1968-1973. This small transmission focus was swiftly eliminated without further dissemination to the other parts of the island. Of the 819 imported cases; 250 cases were P. falciparum infection, 516 cases were P. vivax, 19 cases were P. malariae, 18 cases were P. ovale and 16 cases were mixed infection of P. falciparum with other parasite species. among the imported malaria cases with P. falciparum (in total 266), six were reported fatal cases before proper diagnose and treatment. Of the 14 relapsing cases; 13 cases were P. malariae infection, and the remaining one case was P. vivax malaria. All the 17 induced malaria cases were caused by the blood transfusion, exclusively with P. malariae infection. It was quite difficult to prove the positive parasitemia directly under microscopy from the blood donors due to very low parasite density of their blood.