"Candidatus anaplasma camelii" in one-humped camels (Camelus dromedarius) in Morocco: a novel and emerging anaplasma species?

Abstract

Background: There has been a growing interest in camel anaplasmosis due to its recent emergence in this reservoir species and concerns for its zoonotic potential. The epidemiology of anaplasmosis in camels therefore remains poorly understood mostly because camels belong to marginalised poor and often transhumant populations whose interests are largely neglected. Most studies of anaplasmosis in camels have relied on microscopy and serology for diagnosis and only three studies, undertaken in Tunisia, Saudia Arabia and China, have used molecular diagnostics. The present work characterises Anaplasmataceae strains circulating in the Camelus dromedarius reservoir in Morocco using PCR.

Methods: Camels (n = 106) were randomly sampled from 6 regions representing different agro-ecological areas in southern Morocco. Whole blood was collected and screened using PCR methods targeting the gene groEL. Anaplasmataceae strains were characterised by sequence analysis of the gene groEL.

Results: A total of 39.62% (42/106) camels screened were positive for Anaplasmataceae spp. GenBank BLAST analysis of five positive sequenced samples revealed that all strains were 100% identical to "Candidatus Anaplasma camelii". Phylogenetic investigation and genetic characterisation of the aligned segment (650 bp) of the gene groEL confirmed high similarity with A. platys.

Conclusion: This study demonstrates the circulation of a previously unidentified species of the genus Anaplasma in Morocco which is genetically close to the agent causing canine anaplasmosis but whose main reservoir is thought to be Camelus dromedarius.

Trial registration number: This study is not a clinical trial and therefore a trial registration number does not apply.

Keywords: Anaplasma camelii; Morocco; One-humped camel (Camelus dromedarius); Phylogeny; Tick-borne; groEL.

Fig. 1

Map of Moroccan regions sampled

Fig. 2

Dependent oedema in the region of the sternum and xiphoid in a 6 years old female camel

Fig. 3

Phylogenetic tree of the groEL gene derived from Moroccan camel strains of Anaplasma sp. The tree was obtained using the neighbour joining method with software Mega after alignment with ClustalW of 650 bp sequences of the groEL gene from this study and Anaplasma sp. sequences available from GenBank from various host species and countries of origin. We used Kimura 2-parameter method to calculate distance matrices. In each node, percentages of bootstrap values (1 000 repeats) are indicated

Fig. 4

Mass tick infestation in a juvenile camel. Pruritus promotes hair loss in the thoracic region and head wounds through excessive rubbing

Fig. 5

Mass tick infestation in a juvenile camel