Volume 193 - Issue 8
Complexity of risk for transfusion malaria and differentiated response to risk management
Authors: Bryan R Spencer and Louis M Katz
Med J Aust 2010; 193 (8): 484. || doi: 10.5694/j.1326-5377.2010.tb04011.x
Published online: 18 October 2010
Published online: 18 October 2010
To the Editor: We read with interest the article by Seed and colleagues1 about the collection and distribution of blood from two donors diagnosed with Plasmodium vivax malaria following travel to Papua New Guinea (PNG). Although the potentially infectious blood components were recalled before transfusion, this case underscores the complexity of managing the risk of transfusion-transmitted malaria (TTM).
Three points in particular are worth noting. First, the donors were asymptomatically harbouring infection at donation following routine foreign travel. (Between 1963 and 1999 in the United States, only one donor was implicated in TTM following routine travel, compared with more than 30 donors with lengthy residence in Sub-Saharan Africa.2) Second, both donors acquired malaria despite observing Australian guidelines for chemoprophylaxis. Finally, both were non-reactive on the enzyme immunoassay (EIA) used to screen their donations (Malaria EIA, NewLabs, Newmarket, United Kingdom) after intervals of 4 and 13 months between return from PNG and their donations.
Interestingly, chemoprophylaxis for these donors was both the cause and a potential solution for the “near-miss” event. The primary prophylactic regimens used were sufficient to modify the primary infection such that antibody response to the blood-stage antigens, on which the EIA is based, occurred only after relapse months later. Had the donors taken primaquine following their travel, the parasitaemia triggered by the hepatic hypnozoite forms that characterize P. vivax infections might well have been prevented. Although primaquine is not universally recommended for terminal prophylaxis, it is consensually recommended for terminal prophylaxis for travellers who have had “intense” or “significant” exposure to P. vivax or Plasmodium ovale, such as PNG would offer.3
Seed and colleagues suggest the need for an exception to blood service management practices for donors who have recently visited a geographic area with distinct epidemiological risk for malaria. Noting the disproportionate risk associated with travel to PNG, they suggest excluding donors with a history of recent visits to PNG from routine testing for malaria (and excluding their donations from fresh component production for an appropriate period). In the United States, regulators are similarly considering carving out an exception for travellers to Mexico,4 a low-risk country where the areas associated with most (approximately 75%) malaria deferrals report near-zero malaria risk (our unpublished data). US data suggest that more than 45 000 donors will be recovered annually if the Mexican state of Quintana Roo is exempted from the deferral requirements, and regulators are weighing this benefit against the exquisitely low added risk. The outcome of this deliberation is pending, but the fact that risk gradients within a given risk category are prompting consideration of differentiated management in two countries is notable.
References
- Seed CR, Coughlin JT, Pickworth AM, et al. Relapsing vivax malaria despite chemoprophylaxis in two blood donors who had travelled to Papua New Guinea. Med J Aust 2010; 192: 471-473. 0_i1095402
- Mungai M, Tegtmeier G, Chamberland M, Parise M. Transfusion-transmitted malaria in the United States from 1963 through 1999. N Engl J Med 2001; 344: 1973-1978. 0_CBBDCHBA
- Hill DR, Baird JK, Parise ME, et al. Primaquine: report from CDC Expert Meeting on Malaria Chemoprophylaxis I. Am J Trop Med Hyg 2006; 75: 402-415. 0_i1095407
- United States Food and Drug Administration. Blood Products Advisory Committee 96th Meeting, 2009. Topic 1: Blood donor deferral for malaria risk associated with travel to Mexico. http://www.fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/BloodVaccinesandOtherBiologics/ BloodProductsAdvisoryCommittee/UCM189010.pdf (accessed Jul 2010).