Deconstructing the risk for malaria in United States donors deferred for travel to Mexico

Abstract

Background: More than 66,000 blood donors are deferred annually in the United States due to travel to malaria-endemic areas of Mexico. Mexico accounts for the largest share of malaria travel deferrals, yet it has extremely low risk for malaria transmission throughout most of its national territory, suggesting a suboptimal balance between blood safety and availability. This study sought to determine whether donor deferral requirements might be relaxed for parts of Mexico without compromising blood safety.

Study design and methods: Travel destination was recorded from a representative sample of presenting blood donors deferred for malaria travel from six blood centers during 2006. We imputed to these donors reporting Mexican travel a risk for acquiring malaria equivalent to Mexican residents in the destination location, adjusted for length of stay. We extrapolated these results to the overall US blood donor population.

Results: Risk for malaria in Mexico varies significantly across endemic areas and is greatest in areas infrequently visited by study donors. More than 70% of blood donor deferrals were triggered by travel to the state of Quintana Roo on the Yucatán Peninsula, an area of very low malaria transmission. Eliminating the travel deferral requirement for all areas except the state of Oaxaca might result in the recovery of almost 65,000 blood donors annually at risk of approximately one contaminated unit collected every 20 years.

Conclusion: Deferral requirements should be relaxed for presenting donors who traveled to areas within Mexico that confer exceptionally small risks for malaria, such as Quintana Roo.

Figure 1. States in Mexico where U.S. Centers for Disease Control reports risk for malaria, 2005-2006

Sources: Map adaptedfrom INEGI; Yellow Book Description from CDC: “Risk in rural areas, including resorts inrural areas, of the following states: Campeche, Chiapas, Guerrero, Michoacan, Nayarit, Oaxaca, Quintana Roo, Sinaloa, and Tabasco. In addition, risk exists in the state of Jalisco (in its mountainous northern area only). Risk also exists in an area between 24°N and 28°N latitude, and 106°W and 110°W longitude, which lies in parts of the states of Sonora, Chihuahua, and Durango. No risk along the United States-Mexico border. No risk in major resorts along the Pacific and Gulf Coasts.”

Figure 2

Mexican State of Quintana Roo, with 2005 county-level malaria risk and general distribution of REDS-II malaria travel deferral destinations. Source: Map adapted from INEGI; malaria incidence derived from online county-level data on malaria cases and population.

Figure 3

Mexican State of Nayarit, with 2005 county-level malaria risk and destination location of large majority of REDS-II malaria travel deferrals. Source: Map adapted from INEGI; malaria incidence derived from online county-level data on malaria cases and population.