Wild boars as hosts of human-pathogenic anaplasma phagocytophilum variants.
Article Type: Letter to the editor
Authors: de la Fuente, Jose
Gortazar, Christian
Pub Date: 12/01/2012
Publication: Name: Emerging Infectious Diseases Publisher: U.S. National Center for Infectious Diseases Audience: Academic; Professional Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2012 U.S. National Center for Infectious Diseases ISSN: 1080-6040
Issue: Date: Dec, 2012 Source Volume: 18 Source Issue: 12
Accession Number: 313345677
Full Text: To the Editor: Michalik et al. (1) reported a 12% prevalence of Anaplasma phagocytophilum, the causative agent of human granulocytic anaplasmosis and tick-borne fever of ruminants, in wild boars in Poland. A. phagocytophilum has been reported with low prevalence among wild boar in the Czech Republic, Slovenia (2), and Japan (3). In Spain and Mississippi, United States, A. phagocytophilum in wild boars or feral pigs, respectively, has not been reported (4,5). Furthermore, in Slovenia and Poland, the A. phagocytophilum gene sequences found in samples from wild boars were identical to those found in samples from humans and the tick vector Ixodes ricinus (1). These results suggested, as pointed out by Michalik et al. (1), that wild boar might play a role in the epizootiology of A. phagocytophilum by serving as a natural reservoir host, at least in some regions.

To test this hypothesis, we conducted transcriptomics studies to characterize host response to A. phagocytophilum infection in naturally and experimentally infected boars (6,7). The results suggested that boars are susceptible to A. phagocytophilum, but are able to control infection, mainly through activation of innate immune responses and cytoskeleton rearrangement to promote phagocytosis and autophagy. Control of A. phagocytophilum infection in boars might result in infection levels below PCR detection or infection clearance, contributing to the low percentage of infection prevalence detected for this species in most regions.

The low detection levels suggest that boars have a low or no impact as a reservoir host for A. phagocytophilum. Even if boars remain persistently infected with A. phagocytophilum at low levels by downregulating some adaptive immune genes and delaying the apoptotic death of neutrophils through activation of the Jak-STAT pathway, among other mechanisms (6), their role as a source of infection for ticks remains to be demonstrated.

Jose de la Fuente and Christian Gortazar

Author affiliations: Instituto de Investigacion en Recursos Cinegeticos, Ciudad Real, Spain (J. de la Fuente, C. Gortazar); and Oklahoma State University, Stillwater, Oklahoma, USA (J. de la Fuente)

DOI: 10.3201/eid1812.120778

References

(1.) Michalik J, Stanczak J, Cieniuch S, Racewicz M, Sikora B, Dabert M. Wild boars as hosts of human-pathogenic Anaplasma phagocytophilum variants. Emerg Infect Dis. 2012;18:998-1001. http://dx.doi. org/10.3201/eid1806.110997

(2.) Strasek Smrdel K, Tozon N, Duh D, Petrovec M, Avsic Zupanc T. Diversity of groESL sequences of Anaplasma phagocytophilum among dogs in Slovenia. Clin Microbiol Infect. 2009;15(Suppl 2):7980. http://dx.doi.org/10.1111/ j.1469-0691.2008.02201.x

(3.) Masuzawa T, Uchishima Y, Fukui T, Okamoto Y, Muto M, Koizumi N, et al. Detection of Anaplasma phagocytophilum from wild boars and deer in Japan. Jpn J Infect Dis. 2011;64:333-6.

(4.) Portillo A, Perez-Martinez L, Santibanez S, Santibanez P, Palomar AM, Oteo JA. Anaplasma spp. in wild mammals and Ixodes ricinus from the north of Spain. Vector Borne Zoonotic Dis. 2011;11:3-8. http:// dx.doi.org/10.1089/vbz.2009.0214

(5.) Castellaw AH, Chenney EF, Varela-Stokes AS. Tick-borne disease agents in various wildlife from Mississippi. Vector Borne Zoonotic Dis. 2011;11:439-42. http:// dx.doi.org/10.1089/vbz.2009.0221

(6.) Galindo RC, de la Fuente J. Transcriptomics data integration reveals Jak-STAT as a common pathway affected by pathogenic intracellular bacteria in natural reservoir hosts. J Proteomics Bioinform. 2012;5:108-15. http://dx.doi.org/10.4172/ jpb.1000221

(7.) Galindo RC, Ayllon N, Strasek Smrdel K, Boadella M, Beltran-Beck B, Mazariegos M, et al. Gene expression profile suggests that pigs (Sus scrofa) are susceptible to Anaplasma phagocytophilum but control infection. Parasit Vectors. 2012;5:181. http://dx.doi.org/10.1186/1756-3305-5181

Address for correspondence: Jose de la Fuente, Department of Veterinary Pathobiology, College of Veterinary Medicine, 250 McElroy Hall, Oklahoma State University, Stillwater, OK 74078, USA; email: jose.de_la_fuente@ okstate.edu
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