It is said that malaria was brought into Yaeyama in 1530 by a Dutch ship which drifted ashore on Iriomote Island. From then until the 20th century, malaria in Yaeyama was an endemic disease of unknown cause. In 1921, the first administrative organization of malaria control, "Malaria Prevention Office, Yaeyama Islands Branch" was established. However, with no continuous and fundamental malaria control measures implemented, the number of patients did not decrease. Under such circumstances, Yaeyama became involved in the Battle of Okinawa.

There were no land battles fought in Yaeyama during the Battle of Okinawa. However, as air raids intensified, residents were forcibly evacuated to malaria-endemic areas by the order of the Japanese Army.
Lacking food and medicine, 16,884 people, about half of the population, contracted malaria, resulting in the loss of 3,647 precious lives. In contrast, the death toll from the battle was 178. This malaria disaster during the war is called "Wartime Malaria.”
Dr. Kozen Yoshino, PhD, a parasitologist from Yaeyama, together with Naoki Kuroshima, a public health center official, and others, collected detailed data on the wartime malaria patients. These scientific data led to postwar malaria control measures.
After the war, Dr. Yoshino became Director of the Yaeyama Branch Office, and Dr. Shinken Ohama, PhD, a malariologist from Yaeyama, was appointed Director of the Public Health Department, who drew up "Regulations for Malaria Eradication.” The enforcement of the regulations was strict, with a fine imposed for non-compliance, but owing to the concerted efforts made by the public and private sectors, in 1949 the number of malaria cases decreased to 17 and deaths fell sharply as well.
However, zero malaria had yet to be achieved.

In 1950, the new administration elected by the residents cut the budget for malaria control and pushed forward with a resettlement program. Consequently, many "pioneer immigrants" from other islands settled in malaria-endemic areas, resulting in the resurgence of malaria among them. This is known as "Immigrant Malaria."
In 1957 in Yaeyama, at the request of USCAR (the United States Civil Administration of Ryukyu Islands), Dr. Charles M. Wheeler, a public health entomologist of GHQ in Japan, developed the "Wheeler Plan," a malaria control plan. A special budget was allocated for the plan with a focus on the indoor residual spraying of DDT*, which had been scientifically proven effective in other countries. With thorough spraying operations carried out by health center staff, the effects appeared immediately, and then the residents actively cooperated. As a result, in 1962 Yaeyama achieved zero malaria with the patients in Iriomote in 1961 being the last on record.　　
*DDT was an inexpensive and effective insecticide, but its use was banned due to its hazardous properties.

Malaria is an infectious disease caused by Plasmodium parasites. The disease is characterized by high fever and intense chills, which can lead to death if treatment is delayed. The parasites are transmitted to people through the bites of infected Anopheles mosquitoes. The parasite enters the body through the mosquito’s saliva when it sucks blood. Malaria is one of “the three major infectious diseases in the world,” along with AIDS and tuberculosis.
In Yaeyama, a vector Anopheles yaeyamaensis, which carries Plasmodium falciparum, the most life-threatening malaria species, breeds in jungle streams. Although malaria is no longer present in Yaeyama, it still claims more than 600,000 lives a year in the world, mainly in low- and middle-income countries in tropical and sub-tropical areas in Asia, Africa, etc. (2020)

On July 7, 1950, Inoda village was established in the malaria-endemic area with the
inauguration of “Malaria Eradication Inoda Branch Office,“ which was built by the residents
themselves.
On July 7, 1950, Inoda village was established in the malaria-endemic area with the inauguration of “Malaria Eradication Inoda Branch Office” which was build by the residents themselves. In October 1951, first 21 families from Ogimi village in the main island of Okinawa started to settle in Inoda under the resettlement program, and many other followed, to clear and cultivate the land. Then, a malaria outbreak occurred among the settlers in the northern part of Ishigaki Island, including Inoda. The Inoda Branch Office undertook a wide range of activities including treatment, prevention, mosquito control, as well as public awareness, and it later acted as a focal point in implementing the Wheeler plan in the northern area.
Thanks to all those efforts, in 1962 the annual number of malaria cases was reduced to zero.

Finally, in Yaeyama the over 400-year history of anti-malaria struggle came to an end.