Occurrence of Amblyomma dissimile on wild crocodylians in southern Mexico

Candidatus Rickettsia colombianensi in ticks from reptiles in Córdoba, Colombia

Background and Aim

Wildlife animals are reservoirs of a large number of microorganisms pathogenic to humans, and ticks could be responsible for the transmission of these pathogens. Rickettsia spp. are the most prevalent pathogens found in ticks. This study was conducted to detect Rickettsia spp. in ticks collected from free-living and illegally trafficked reptiles from the Department of Córdoba, Colombia.

Materials and Methods

During the period from October 2011 to July 2014, ticks belonging to the family Ixodidae were collected, preserved in 96% ethanol, identified using taxonomic keys, and pooled (between 1 and 14 ticks) according to sex, stage, host, and collected place for subsequent DNA extraction. Rickettsia detection was performed using real-time polymerase chain reaction (RT-PCR), followed by conventional PCR to amplify a larger fragment of the gltA and 16S rRNA genes. The amplicons were sequenced using the Sanger method, and the nucleotide sequences were subjected to BLAST analysis to identify homologous sequences in GenBank, after which phylogenetic analysis was performed using the MEGA X software.

Results

In total, 21 specimens of nine species of reptiles were sampled, from which 805 Amblyomma dissimile ticks were collected, but only 180 ticks were selected to create 34 groups. The DNA of Rickettsia spp. was detected in 30/34 (88%) groups. The sequences of the gene gltA and 16S rRNA revealed a 100% identity with Candidatus Rickettsia colombianensi (GenBank: KF905456 and GenBank: KF691750).

Conclusion

A. dissimile was the only tick found in all the sampled reptiles. The presence of Candidatus Rickettsia colombianensi in reptile ticks could represent a public health problem due to the risk of transmission to humans and the introduction of microorganisms to other geographical areas.

Tick-crocodilian interactions: a review, with the first record of tick (Acari: Ixodidae) infestation in the saltwater crocodile (Crocodylus porosus), and a concise host-parasite index

Interactions between ticks and crocodilians (crocodiles, alligators, caiman, and gharials) are poorly studied but may have significant bearing on the ecology and health of these reptiles. The first record of tick infestation of the saltwater crocodile (Crocodylus porosus) is reported along with the first case of infestation by Amblyomma cordiferum on Cuvier's dwarf caiman (Paleosuchus palpebrosus). A review is also provided of tick-crocodilian interactions with a concise host-parasite index.

Rickettsia species in ticks that parasitize amphibians and reptiles: Novel report from Mexico and review of the worldwide record

Ticks are obligate haematophagous ectoparasites that are associated with a wide range of vertebrate hosts, among them also reptiles and amphibians. They have dynamic ecological interactions with multiple microorganisms, ranging from endosymbionts to pathogens, such as the members of the genus Rickettsia. The aim of this work was to detect Rickettsia in ticks from amphibians and reptiles from southern Mexico by the amplification, sequencing and phylogenetic reconstruction of the gltA and ompA genes, and also to compile all the published records worldwide of Rickettsia associated with ticks attached to reptiles and amphibians, in order to elucidate the host-parasite relationships, and to identify the geographical distribution of each bacterial species. We record for the first time the presence of Rickettsia sp. strain Colombianensi and Rickettsia amblyommatis in ticks from several reptiles and amphibians collected in three new localities from the states of Guerrero and Veracruz, Mexico. Additionally, we here report 23 Rickettsia taxa associated with 18 tick species attached to 42 host taxa of amphibians and reptiles in 36 countries. Our findings increase the inventory of rickettsia reported in Mexico and summarizes the knowledge of these bacteria associated with ticks of this particular group of vertebrate host worldwide.

Rickettsial infection in ticks (Acari: Ixodidae) from reptiles in the Colombian Caribbean

Although more reptiles are illegally traded in Colombia than any other group of animals, for both local and international markets, little is known about ticks associated with reptiles or pathogens associated with these ticks. In this study, ticks were collected from reptiles in Magdalena, Cesar and La Guajira regions in northern Colombia, and identified morphologically using taxonomic keys and molecularly by sequencing of the COI gene. In addition, Rickettsia spp. were detected by PCR amplifying the gltA, 16S rRNA, and sca1 genes. Ticks were identified as Amblyomma dissimile, representing the first record for this species in 17 of the 26 species of reptiles sampled. Additionally, our data expand the distribution range for this tick in Colombia. Rickettsia spp. DNA was detected in 18 ticks (3.6%) from 16 reptiles. Sequence analyses indicated that most of the Rickettsia were members of the R. monacensis clade, most closely related to Rickettsia sp. strain Colombianensi. We detected one tick infected with a Rickettsia with 99% identity to R. bellii.