Delineating<i>Anaplasma phagocytophilum</i>Ecotypes in Coexisting, Discrete Enzootic Cycles

Bown, Kevin; Lambin, Xavier; Ogden, Nicholas H.; Begon, Michael; Telford, Gill; Woldehiwet, Z.; Birtles, Richard J.

doi:10.3201/eid1512.090178

Cited by 111 publications

(128 citation statements)

References 34 publications

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“…However, sequence analysis revealed that the strains were most closely related to those recovered from large mammals across Europe suggesting that other, large mammal, hosts of I. ricinus present at the study site were responsible for these infections. Moreover, Bown et al (2009) observed that different A. phagocytophilum strains exist in discrete enzootic small mammal and large mammal cycles. The prevalence of infection of I. ricinus nymphs was low (1·12%) and the probability of a mouse feeding a nymph was also low (2·02%).…”

Section: Discussionmentioning

confidence: 99%

“…In Europe, rodents host both larvae and nymphs of I. ricinus (Milne, 1949;Gern et al 1998;Liz et al 2000;Karbowiak, 2004) and are competent transmission hosts of B. microti, A. phagocytophilum and B. burgdorferi s.l. B. microti is a small mammal specific pathogen whilst A. phagocytophilum infects both small mammals and large mammals such as deer, although it is thought that separate A. phagocytophilum strains exist in discrete small mammal and large mammal cycles (Bown et al 2009). Members of the B. burgdorferi s.l.…”

Section: Introductionmentioning

confidence: 99%

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Investigating the persistence of tick-borne pathogens via the R₀model

2011

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In the epidemiology of infectious diseases, the basic reproduction number, R 0 , has a number of important applications, most notably it can be used to predict whether a pathogen is likely to become established, or persist, in a given area. We used the R 0 model to investigate the persistence of 3 tick-borne pathogens; Babesia microti, Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in an Apodemus sylvaticus-Ixodes ricinus system. The persistence of these pathogens was also determined empirically by screening questing ticks and wood mice by PCR. All 3 pathogens behaved differently in response to changes in the proportion of transmission hosts on which I. ricinus fed, the efficiency of transmission between the host and ticks and the abundance of larval and nymphal ticks found on small mammals. Empirical data supported theoretical predictions of the R 0 model. The transmission pathway employed and the duration of systemic infection were also identified as important factors responsible for establishment or persistence of tick-borne pathogens in a given tick-host system. The current study demonstrates how the R 0 model can be put to practical use to investigate factors affecting tick-borne pathogen persistence, which has important implications for animal and human health worldwide.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigating the persistence of tick-borne pathogens via the R₀model

2011

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“…In contrast, the role of the white-tailed deer, Odocoileus virginianus, has been questioned (38,40) because it might harbor A. phagocytophilum strains not infectious for humans. In Europe, A. phagocytophilum has been detected in wildlife such as roe deer, red deer, and rodents (1,35,36,42,44), but their specific function in the transmission cycle of A. phagocytophilum is not completely understood (8).…”

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confidence: 99%

“…Most often the 16S rRNA gene was used, and a different pathogenic potential of distinct 16S rRNA gene variants of A. phagocytophilum has been suggested (40,60). However, 16S rRNA gene sequences were shown to not be informative enough to delineate distinct genotypes of A. phagocytophilum (8,9,12,71). Other genes that were used for typing include the groESL heat shock operon (64), the msp4 gene encoding one of the major surface proteins (17), and the ankA gene (39).…”

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Distinct Host Species Correlate with Anaplasma phagocytophilum ankA Gene Clusters

et al. 2011

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Anaplasma phagocytophilum is a Gram-negative, tick-transmitted, obligate intracellular bacterium that elicits acute febrile diseases in humans and domestic animals. In contrast to the United States, human granulocytic anaplasmosis seems to be a rare disease in Europe despite the initial recognition of A. phagocytophilum as the causative agent of tick-borne fever in European sheep and cattle. Considerable strain variation has been suggested to occur within this species, because isolates from humans and animals differed in their pathogenicity for heterologous hosts. In order to explain host preference and epidemiological diversity, molecular characterization of A. phagocytophilum strains has been undertaken. Most often the 16S rRNA gene was used, but it might be not informative enough to delineate distinct genotypes of A. phagocytophilum. Previously, we have shown that A. phagocytophilum strains infecting Ixodes ricinus ticks are highly diverse in their ankA genes. Therefore, we sequenced the 16S rRNA and ankA genes of 194 A. phagocytophilum strains from humans and several animal species. Whereas the phylogenetic analysis using 16S rRNA gene sequences was not meaningful, we showed that distinct host species correlate with A. phagocytophilum ankA gene clusters.

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“…50,51 We have focused on two of these strains, one of which is found in many wildlife hosts and humans (A. phagocytophilum-ha) and the other one of which is found in many wildlife hosts but not humans (A. phagocytophilum-v1). Future research should continue to investigate the origins and consequences of strain diversity in A. phagocytophilum, particularly because it affects variation in human risk of exposure to this emerging pathogen.…”

Section: Discussionmentioning

confidence: 99%

Prevalence of Human-Active and Variant 1 Strains of the Tick-Borne Pathogen Anaplasma phagocytophilum in Hosts and Forests of Eastern North America

Keesing¹,

McHenry²,

Hersh³

et al. 2014

The American Society of Tropical Medicine and Hygiene

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Abstract. Anaplasmosis is an emerging infectious disease caused by infection with the bacterium Anaplasma phagocytophilum. In the eastern United States, A. phagocytophilum is transmitted to hosts through the bite of the blacklegged tick, Ixodes scapularis. We determined the realized reservoir competence of 14 species of common vertebrate hosts for ticks by establishing the probability that each species transmits two important strains of A. phagocytophilum (A. phagocytophilum human-active, which causes human cases, and A. phagocytophilum variant 1, which does not) to feeding larval ticks. We also sampled questing nymphal ticks from~150 sites in a single county over 2 years and sampled over 6 years at one location. White-footed mice (Peromyscus leucopus) and Eastern chipmunks (Tamias striatus) were the most competent reservoirs for infection with the A. phagocytophilum human-active strain. Across the county, prevalence in ticks for both strains together was 8.3%; ticks were more than two times as likely to be infected with A. phagocytophilum human-active as A. phagocytophilum variant 1.

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DelineatingAnaplasma phagocytophilumEcotypes in Coexisting, Discrete Enzootic Cycles

Abstract: Genetically distinct subpopulations have adapted to different niches

Cited by 111 publications

References 34 publications

Investigating the persistence of tick-borne pathogens via the R₀model

Investigating the persistence of tick-borne pathogens via the R₀model

Distinct Host Species Correlate with Anaplasma phagocytophilum ankA Gene Clusters

Prevalence of Human-Active and Variant 1 Strains of the Tick-Borne Pathogen Anaplasma phagocytophilum in Hosts and Forests of Eastern North America

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DelineatingAnaplasma phagocytophilumEcotypes in Coexisting, Discrete Enzootic Cycles

Abstract: Genetically distinct subpopulations have adapted to different niches

Cited by 111 publications

References 34 publications

Investigating the persistence of tick-borne pathogens via the R0model

Investigating the persistence of tick-borne pathogens via the R0model

Distinct Host Species Correlate with Anaplasma phagocytophilum ankA Gene Clusters

Prevalence of Human-Active and Variant 1 Strains of the Tick-Borne Pathogen Anaplasma phagocytophilum in Hosts and Forests of Eastern North America

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Investigating the persistence of tick-borne pathogens via the R₀model

Investigating the persistence of tick-borne pathogens via the R₀model