A novel ehrlichial agent detected in tick in French Polynesia

A novel Ehrlichia strain (Rickettsiales: Anaplasmataceae) detected in Amblyomma triste (Acari: Ixodidae), a tick species of public health importance in the Southern Cone of America

The aim of this work was to report the detection of a putative novel Ehrlichia strain associated with the tick Amblyomma triste. Free-living adult ticks determined as A. triste were collected by drag-sampling in Argentina and Uruguay. Molecular detection of Ehrlichia agents was performed targeting three different loci: 16S rRNA gene, dsb gene and a fragment of groESL heat shock operon. In total, 164 adults of A. triste (38 from INTA E.E.A Delta del Paraná in Argentina and 126 from Toledo Chico in Uruguay) were analyzed. One tick (0.6%) collected in INTA E.E.A. Delta del Paraná (Argentina) was positive. The phylogenetic analyses show that the Ehrlichia strain found in this study (named Ehrlichia sp. strain Delta) represents an independent lineage within the genus Ehrlichia, close to E. chaffeensis and E. muris. This is also the first report of an Ehrlichia agent infecting the tick A. triste. The medical and veterinary significance of Ehrlichia sp. strain Delta remains to be demonstrated. However, it is important to mention that adults of A. triste are aggressive to humans and domestic mammals. Therefore, the potential role of A. triste in the transmission of Ehrlichia agents to humans or domestic animals across its distributional range should be highlighted, even more considering that Ehrlichia sp. strain Delta is phylogenetically related to the zoonotic E. chaffeensis, which is recognized as pathogenic to both humans and animals.

Ticks and Tick-Borne Pathogens of the Caribbean: Current Understanding and Future Directions for More Comprehensive Surveillance

Ticks are obligate hematophagous arthropods of significant importance to human and veterinary medicine. They transmit a vast array of pathogens, including bacteria, viruses, protozoa, and helminths. Most epidemiological data on ticks and tick-borne pathogens (TBPs) in the West Indies are limited to common livestock pathogens such as Ehrlichia ruminantium, Babesia spp. (i.e., B. bovis and B. bigemina), and Anaplasma marginale, and less information is available on companion animal pathogens. Of note, human tick-borne diseases (TBDs) remain almost completely uncharacterized in the West Indies. Information on TBP presence in wildlife is also missing. Herein, we provide a comprehensive review of the ticks and TBPs affecting human and animal health in the Caribbean, and introduce the challenges associated with understanding TBD epidemiology and implementing successful TBD management in this region. In particular, we stress the need for innovative and versatile surveillance tools using high-throughput pathogen detection (e.g., high-throughput real-time microfluidic PCR). The use of such tools in large epidemiological surveys will likely improve TBD prevention and control programs in the Caribbean.

Detection of relapsing fever Borrelia spp., Bartonella spp. and Anaplasmataceae bacteria in argasid ticks in Algeria

BACKGROUND

Argasid ticks (soft ticks) are blood-feeding arthropods that can parasitize rodents, birds, humans, livestock and companion animals. Ticks of the Ornithodoros genus are known to be vectors of relapsing fever borreliosis in humans. In Algeria, little is known about relapsing fever borreliosis and other bacterial pathogens transmitted by argasid ticks.

METHODOLOGY/PRINCIPAL FINDINGS

Between May 2013 and October 2015, we investigated the presence of soft ticks in 20 rodent burrows, 10 yellow-legged gull (Larus michahellis) nests and animal shelters in six locations in two different bioclimatic zones in Algeria. Six species of argasid ticks were identified morphologically and through 16S rRNA gene sequencing. The presence and prevalence of Borrelia spp., Bartonella spp., Rickettsia spp. and Anaplasmataceae was assessed by qPCR template assays in each specimen. All qPCR-positive samples were confirmed by standard PCR, followed by sequencing the amplified fragments. Two Borrelia species were identified: Borrelia hispanica in Ornithodoros occidentalis in Mostaganem, and Borrelia cf. turicatae in Carios capensis in Algiers. One new Bartonella genotype and one new Anaplasmataceae genotype were also identified in Argas persicus.

CONCLUSIONS

The present study highlights the presence of relapsing fever borreliosis agents, although this disease is rarely diagnosed in Algeria. Other bacteria of unknown pathogenicity detected in argasid ticks which may bite humans deserve further investigation.