Posts or Comments 27 January 2022

Elimination &Monkeys &Zoonoses Bill Brieger | 09 Jan 2022 06:32 am

Humans, Monkeys, and Malaria in Costa Rica: Implications for Elimination

A just-published article by Andrea Chaves and colleagues entitled, “Presence and potential distribution of malaria-infected New World primates of Costa Rica”, Specifically their results state that, “PCR analysis for the Plasmodium presence was conducted in 384 samples of four primates …

  • Howler monkey [n?=?130]
  • White-face monkey [n?=?132]
  • Squirrel monkey [n?=?50]
  • red spider monkey [n?=?72]),

… from across Costa Rica. Three Plasmodium species were detected in all primate species (P. falciparum, P. malariae/P. brasilianum, and P. vivax). Overall, the infection prevalence was 8.9%, but each Plasmodium species ranged 2.1–3.4%. The niche model approach showed that the Pacific and the Atlantic coastal regions of Costa Rica presented suitable climatic conditions for parasite infections. However, the central pacific coast has a more trustable prediction for malaria in primates.”

Last year, Tobias Mourier et al. reported another human/non-human primate connection in Brazil. According to them, “Analysis of the P. simium genome confirmed a close phylogenetic relationship between P. simium and P. vivax, and suggests a very recent American origin for P. simium. The presence of the DBP1 deletion in all human-derived isolates tested suggests that this deletion, in combination with other genetic changes in P. simium, may facilitate the invasion of human red blood cells and may explain, at least in part, the basis of the recent zoonotic infections.

The connection between human and primate malaria also flows toward humans as traditional human plasmodium infections decrease in prevalence in Malaysia. Lai are co-researchers explain that, “The incidence of zoonotic malaria Plasmodium knowlesi infection is increasing and now has been the major cause of malaria in Malaysia.”

In fact, the 2021 World Malaria Report noted that, “Malaysia had no cases of human malaria for 3 consecutive years, but in 2020 reported 2607 cases of P. knowlesi, a zoonotic malaria.” The report does not specify efforts to handle this issue.

These studies raise a continuing question about the feasibility of eliminating malaria in countries when those plasmodium species that infect humans also infect other primates and vice versa. As we have noted before, monkeys do not use bednets. As long as primate Plasmodium reservoirs exist, our ability to eliminate the disease will remain elusive.

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