Reassessment of blood donor selection criteria for United States travelers to malarious areas

Abstract

In the United States (US), travelers who have had malaria or who have taken antimalarial chemoprophylaxis are deferred as blood donors for 3 years to prevent transfusion-transmitted malaria. To assess the impact of shortening this 3-year exclusion period, national malaria surveillance data from 1972 to 1988 were reviewed. The average annual rate of transfusion-transmitted malaria is 0.25 cases per million units of blood collected. Of 45 reported cases, 38 percent were caused by Plasmodium malariae, 29 percent by P. falciparum, 24 percent by P. vivax, and 9 percent by P. ovale. Thirty-two donors were implicated in 34 cases of transfusion-transmitted malaria. Of 30 implicated donors whose native country was identified, 23 (77%) were foreign nationals and 7 (23%) were from the US. In a review of all imported malaria cases by species and by interval between date of entry and onset of illness, 98 percent of P. falciparum, 86 percent of P. malariae, 76 percent of P. vivax, and 74 percent of P. ovale infections became symptomatic within 6 months of the patient's arrival in the US, regardless of the use of prophylaxis. Shortening to 6 months the donor exclusion period for US travelers to malarious areas would result in a minimum of 70,000 additional blood donors' being made available, with a maximum annual increase of 0.03 additional cases of transfusion-transmitted malaria. The potential benefit of bringing healthy travelers back into the donor pool after a shorter period of exclusion merits consideration by the blood banking industry.

Current Concepts on Transmission of Bacteria and Parasites by Blood Components

“…number of healthy donors. A recent study in the USA (95), where the incidence of TxM is 0.25 cases/ million units, claims that by reducing the interval to 6 months after travel, irrespective of prophylaxis, some 70,000 to 315,000 additional blood units could be collected a year with an additional calculated risk of 0.03 cases/million units in the annual incidence. The authors stated that the 6-month deferral was accurate for 88% of cases, and the 3-year deferral period used for preventing P. vivax and P. ovale (which accounted for only 33% of cases) would have prevented only one case in 17 years.…”

“…The authors stated that the 6-month deferral was accurate for 88% of cases, and the 3-year deferral period used for preventing P. vivax and P. ovale (which accounted for only 33% of cases) would have prevented only one case in 17 years. Low sensitivity -After a careful examination of all cases of TxM in the USA, it was stated that at least 50% of them could be avoided if the aforementioned questionnaire were correctly filled out (95). The interviewer has also to rely upon the accuracy of the donors' history, which may be fallible in most cases.…”

“…Detection of antigens -The easiest one is the thick smear test, however it lacks sensitivity, with a limit of 100 parasites/l, which is more than the minimum necessary for transmission; it is also highly subjective and cannot be used as a mass screening method. One study showed prevention by thick smear in only 10% of TxM, and positivity in 31 % (8/26) of donors implicated in TxM in the USA (95). The detection of parasites within erythrocytes, or of soluble antigens, has been achieved by RIA, ELISA or IIF, the latter mainly in endemic countries (86).…”

Prevalencia de anticuerpos antimaláricos en donantes del banco de sangre del Hospital Universitario San Vicente de Paúl de Medellín, Colombia

“…Cabe destacar que 57% (4 casos) de los sueros positivos para anticuerpos antimaláricos, pertenecían a personas que afirmaron no haber estado en zona endémica para malaria; esto podría indicar que tales donantes posiblemente no informaron la verdad en el momento de la encuesta, o no recordaron sus episodios anteriores de malaria, o no saben cuáles son las zonas endémicas para malaria; estas fallas también se han informado en otros trabajos (5,41).…”

“…La incidencia de malaria transfusional (MT) varía considerablementeentre 1967 y 1997, pues a entre 0,25 casos por millón de unidades pesar del descenso en las muestras examinadas, transfundidas (Estados Unidos, Reino Unido) y que disminuyeron en un 29,3%, la infección más de 50 casos por millón en algunas regiones malárica aumentó en 580,8% y, específicamente, endémicas (3)(4)(5). la infección por Plasmodium falciparum en ese mismo período aumentó 468.9% (datos no La sangre almacenada entre 4 y 6 "C mantiene publicados) la viabilidad de los parásitos hasta por 14 días, aunque la mayoría de las infecciones transfusionales han ocurrido cuando la sangre ha sido almacenada menos de 5 días (6)(7)(8).…”