NEW YORK, Apr 01 (Reuters Health) -- Blood transfusions given to patients in the US carry a very small risk of transmitting malaria, according to a report released Thursday by the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia.
Only about one case of malaria occurs for every 4 million units of blood collected, but closer questioning of donors could lower that infection rate even further, according to the CDC.
Between 1958 and 1998, there were 103 cases in which malaria was contracted after a blood transfusion, and in the three cases that occurred between 1996 and 1998 in Missouri and Pennsylvania, two patients died of the disease.
The two men who died were in their 70s or 80s, and the third, a 49-year-old man, became ill but recovered. None of the patients had recently traveled outside the US, and the parasitic infection was traced to the donated blood.
One donor was a US Army reservist who immigrated to the US from west Africa in 1996, one was a recruit at a military training base who had immigrated to the US from west Africa in 1995, and a third had lived in west Africa for 20 years before moving to the US.
"Because no approved tests are available in the United States to screen donated blood for malaria, prevention of transfusion-transmitted malaria requires careful questioning of prospective donors," according to the CDC report.
People who have emigrated from regions of the world where malaria is endemic can become immune and exhibit no symptoms of the infection. Although the parasite rarely persists in the blood beyond 2 years in such individuals, in rare cases, certain species have remained in the blood for up to 40 years -- making it next-to-impossible to completely eliminate the malaria risk.
However, the three cases in Missouri and Pennsylvania may have been prevented with better donor screening, according to the CDC.
The federal agency is working with the Food and Drug Administration to develop new guidelines for blood collection centers on screening potential donors.
SOURCE: Morbidity and Mortality Weekly Report 1999;48:253-256.
