Emerg Infect DisEmerging Infect. DisEIDEmerging Infectious Diseases1080-60401080-6059Centers for Disease Control and Prevention22000395331068311-071910.3201/eid1710.110719Letters to the EditorPlasmodium vivax Seroprevalence in Bred Cynomolgus Monkeys, China1P. vivax Seroprevalence in Bred Cynomolgus MonkeysElmoreDavid B.DBE Veterinary Consulting, San Diego, California, USAAddress for correspondence: David B. Elmore, DBE Veterinary Consulting, 1785 Guizot St, San Diego, CA 92107, USA; email: dbevetcon@aol.com102011171019781979Keywords: cynomolgus monkeymalariaPlasmodium vivaxseroprevalenceparasitesnonhuman primatemacaqueChinaletter

To the Editor: Having worked with numerous species of research nonhuman primates over the past 26 years, I have a keen interest in related occupational health and safety. In this regard, I was quite interested in the recent report by Li et al. (1) and have some comments and questions relative to this article.

The occurrence of Plasmodium spp. infection in feral primates, feral source captive primates, or primates bred outdoors in malaria-endemic areas is not uncommon. However, with the exception of P. knowlesi, it is my understanding that malarial organisms found in cynomolgus monkeys do not pose a major zoonotic concern (although this can always change). Furthermore, it is my understanding that P. vivax does not infect macaques, including cynomolgus monkeys.

Other malarial parasites of cynomolgus monkeys, apart from P. knowlesi, may include P. cynomologi, P. inui, P. fieldi, and P. coatneyi. A recent publication reported that in wild-source cynomolgus monkeys in Malaysia, >90% of the animals tested were positive for >1 Plasmodium species. Furthermore, >80% of samples from these animals were positive by specific PCR for >1 of these organisms (2).

Using PCR for Plasmodium spp. identification, I have tested newly imported research cynomolgus monkeys from various breeding centers in China. I can confirm that some animals have subclinical malarial infections.

Except for the report by Li et al. (1), I am unaware of other reports of P. vivax in cynomolgus monkeys. It would be interesting to confirm the presence of this organism by using PCR primers specific for Plasmodium spp. My questions to the authors relate to the test method used in their study. Was an ELISA for detecting P. vivax antibodies the only diagnostic method used to identify this parasite? It may be useful to re-address the specificity of this test in differentiating various Plasmodium spp. Until these issues are clearly addressed, their reported results are not reliable.

Suggested citation for this article: Elmore DB. Plasmodium vivax seroprevalence in bred cynomolgus monkeys, China [letter]. Emerg Infect Dis [serial on the Internet]. 2011 Oct [date cited]. http://dx.doi.org/10.3201/eid1710.110719

Li et al. have declined to respond to this letter.

ReferencesLi H-L, Liu Z-Y, Li J, Ai L, Zhou D-H, Yuan Z-G, Plasmodium vivax seroprevalence in bred cynomolgus monkeys, China. Emerg Infect Dis. 2011;17:928921529415Lee K-S, Divis PCS, Zakaria SK, Matusop A, Julin RA, Conway DJ, Plasmodium knowlesi: reservoir hosts and tracking the emergence in humans and macaques. PLoS Pathog. 2011;7:e1002015 10.1371/journal.ppat.100201521490952