When two cases of malaria surfaced in New Haven late last year, they were of interest to clinicians not because of any epidemiological threat, but for the treatment problems they posed. Both cases were imported, rather than transmitted within North America. Both patients had contracted malaria during visits to West Africa to visit family. One was 24 weeks pregnant and one was found to be HIV-positive.

The clinicians treating the HIV-positive patient, according to Frank J. Bia, M.D., M.P.H., professor of medicine and laboratory medicine, speaking at grand rounds in January, were concerned about the interactions between HIV infection and malaria. In the case of the pregnant patient, noted Marissa Wilck, M.D., Winchester Fellow in Clinical Microbiology, clinicians were interested in the interaction of hemoglobinopathy and malaria. Ultrasound revealed the woman’s fetus to be healthy.

A distant memory in the developed world, malaria is thriving in 91 countries (See cover story, To the vector go the spoils). In southern Asia, Africa and Latin America, malaria affects about 300 million people annually and kills as many as 1.5 million each year, mostly children. Malaria has defeated eradication efforts, which were abandoned 30 years ago in favor of control strategies. It has become resistant to synthetic cures such as chloroquine and, with increased ease of travel, threatens to reach places where it was thought to be done away with. It is not unusual to see imported cases at Yale-New Haven Hospital, Wilck said. New York City, with its large population of immigrants, Bia said, has reported cases of transmitted, as well as imported, malaria.

Western medicine first found a remedy for malaria in the 17th century, when a Jesuit missionary in Peru was cured with the bark of the cinchona tree. It was thereafter known as Jesuit’s bark or Peruvian bark. Its active ingredient was quinine.

The pathogen’s portal into the body remained a mystery until 1898, when Ronald Ross, a British physician with the India Medical Service, identified the female Anopheles mosquito as a vector. Malaria is believed to be 30 million years old, and humans are not its only vertebrate target. Other primates, even birds, have their own forms of malaria infection.