Hemoglobin E protects against acute Plasmodium vivax infections in a Kachin population at the China-Myanmar border

Objectives: Hemoglobin E (HbE, beta(26)(Glu-Lys)) is the most prevalent hemoglobinopathy in Southeast Asia. This study aimed to determine whether HbE protects against clinical Plasmodium vivax malaria in Southeast Asia. Methods: In a case-control study performed in villages along the China-Myanmar border, we determined the prevalence of HbE in 257 villagers who had acute P. vivax infections and in 157 control healthy villagers. Results: HbE in P. vivax patients (17.4%) was significantly less prevalent than in the healthy villager population (36.3%). Moreover, there was a complete lack of HbEE homozygotes in the vivax patients as compared to 9.5% prevalence in the healthy villagers. Using the HbAA group as the reference, both the HbEA heterozygotes and HbEE homozygotes had significantly lower odds of presenting with acute P. vivax infections. Furthermore, HbEA heterozygotes also had significantly lower P vivax asexual parasite densities. HbEA did not affect the proportion of P. vivax patients with gametocytemia nor the gametocyte densities. Conclusions: HbE offers significant protection against the occurrence and parasite density of acute P. vivax infections and provides a renewed perspective on P. vivax malaria as a potentially strong driving force behind the high frequencies of HbE in the Kachin population. (C) 2018 The British Infection Association. Published by Elsevier Ltd. All rights reserved.