TO Westerners, the repatriation of five nurses and a doctor to Bulgaria last week after more than eight years’ imprisonment meant the end of an unsettling ordeal. The medical workers, who in May 2004 were sentenced to death on charges of intentionally infecting hundreds of Libyan children with H.I.V., have been freed, and another international incident is averted.

But to many Africans, the accusations, which have been validated by a guilty verdict and a promise to reimburse the families of the infected children with a $426 million payout, seem perfectly plausible. The medical workers’ release appears to be the latest episode in a health care nightmare in which white and Western-trained doctors and nurses have harmed Africans — and have gone unpunished.

The evidence against the Bulgarian medical team, like H.I.V.-contaminated vials discovered in their apartments, has seemed to Westerners preposterous. But to dismiss the Libyan accusations of medical malfeasance out of hand means losing an opportunity to understand why a dangerous suspicion of medicine is so widespread in Africa.

Africa has harbored a number of high-profile Western medical miscreants who have intentionally administered deadly agents under the guise of providing health care or conducting research. In March 2000, Werner Bezwoda, a cancer researcher at South Africa’s Witwatersrand University, was fired after conducting medical experiments involving very high doses of chemotherapy on black breast-cancer patients, possibly without their knowledge or consent. In Zimbabwe, in 1995, Richard McGown, a Scottish anesthesiologist, was accused of five murders and convicted in the deaths of two infant patients whom he injected with lethal doses of morphine. And Dr. Michael Swango, ultimately convicted of murder after pleading guilty to killing three American patients with lethal injections of potassium, is suspected of causing the deaths of 60 other people, many of them in Zimbabwe and Zambia during the 1980s and ’90s. (Dr. Swango was never tried on the African charges.)