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Fulltext Molecular evidence of potential novel spotted fever group rickettsiae, Anaplasma and Ehrlichia species in Amblyomma ticks parasitizing wild snakes

Kho KL, Koh FX, Tay ST

Parasit Vectors, 2015;8:112.
PMID: 25889376 DOI: 10.1186/s13071-015-0719-3

Amblyomma ticks parasitize a wide range of animals in tropical regions. This study describes the identification of Amblyomma ticks from wild snakes in Malaysia and the detection of potential human pathogens such as Rickettsia, Anaplasma, Ehrlichia and bartonellae in the ticks.

Matched MeSH terms: Ehrlichia/genetics
Characterization of the SF agent, an Ehrlichia sp. isolated from the fluke Stellantchasmus falcatus, by 16S rRNA base sequence, serological, and morphological analyses

Wen B, Rikihisa Y, Yamamoto S, Kawabata N, Fuerst PA

Int. J. Syst. Bacteriol., 1996 Jan;46(1):149-54.
PMID: 8573488

The organism designated the SF agent was originally isolated in Japan in 1962 from Stellantchasmus falcatus metacercaria parasitic on gray mullet fish. The SF agent resembles members of the genus Ehrlichia morphologically and exhibits weak antigenic cross-reactivity with Ehrlichia sennetsu. This organism causes mild clinical signs in dogs, but severe splenomegaly and lymphadenopathy in mice. This suggests that the SF agent may be similar to either Neorickettsia helminthoeca, an intracellular parasite of a fluke and the cause of salmon poisoning disease in dogs, or E. sennetsu, the causative agent of human sennetsu ehrlichiosis in Japan and Malaysia. In order to determine the phylogenetic relationship between the SF agent and other ehrlichial species, the 16S rRNA gene was amplified by the PCR and sequenced. The SF agent sequence was most closely related to the sequences of Ehrlichia risticii (level of sequence similarity, 99.1%), the causative agent of Potomac horse fever, and E. sennetsu (level of sequence similarity, 98.7%). The next most similar sequence was that of N. helminthoeca, but the level of sequence similarity was only 93.7%. E. sennetsu, E. risticii, the SF agent, and N. helminthoeca formed a distinct cluster that was separated from all other ehrlichial species. As determined by immunofluorescence labeling, antiserum against the SF agent cross-reacted strongly with E. sennetsu, E. risticii, and N. helminthoeca. When three genetically distinct ehrlichial isolates obtained from horses with Potomac horse fever were compared with the SF agent, we found that the SF agent was most closely related to Ohio isolate 081, followed by IllinoisT (T = type strain) and a Kentucky isolate. We observed strong antigenic cross-reactivities and similarities in Western blot (immunoblot) reaction profiles when we compared the SF agent, E. risticii, and E. sennetsu; however, weaker antigenic cross-reactivity was observed when the SF agent and N. helminthoeca were compared. Our results indicate that the SF agent is antigenically more closely related to E. risticii and E. sennetsu than to N. helminthoeca. The biological and antigenic characteristics and the 16S rRNA sequence data suggest that the SF agent is a new species that belongs to the genus Ehrlichia.

Matched MeSH terms: Ehrlichia/genetics
Molecular investigation of Anaplasma spp. in domestic and wildlife animals in Peninsular Malaysia

Koh FX, Panchadcharam C, Sitam FT, Tay ST

Vet Parasitol Reg Stud Reports, 2018 08;13:141-147.
PMID: 31014863 DOI: 10.1016/j.vprsr.2018.05.006

Anaplasma spp. are Gram-negative obligate intracellular, tick-borne bacteria which are of medical and veterinary importance. Little information is available on Anaplasma infection affecting domestic and wildlife animals in Malaysia. This study investigated the presence of Anaplasma spp. in the blood samples of domestic and wildlife animals in Peninsular Malaysia, using polymerase chain reaction (EHR-PCR) assays targeting the 16S rRNA gene of Anaplasmataceae. High detection rates (60.7% and 59.0%, respectively) of Anaplasma DNA were noted in 224 cattle (Bos taurus) and 78 deer (77 Rusa timorensis and one Rusa unicolor) investigated in this study. Of the 60 amplified fragments obtained for sequence analysis, Anaplasma marginale was exclusively detected in cattle while Anaplasma platys/Anaplasma phagocytophilum was predominantly detected in the deer. Based on sequence analyses of the longer fragment of the 16S rRNA gene (approximately 1000 bp), the occurrence of A. marginale, Anaplasma capra and Candidatus Anaplasma camelii in cattle, Candidatus A. camelii in deer and Anaplasma bovis in a goat was identified in this study. To assess whether animals were infected with more than one species of Anaplasma, nested amplification of A. phagocytophilum, A. bovis and Ehrlichia chaffeensis DNA was performed for 33 animal samples initially screened positive for Anaplasmataceae. No amplification of E. chaffeensis DNA was obtained from animals investigated. BLAST analyses of the 16S rDNA sequences from three deer (R. timorensis), a buffalo (Bubalus bubalis) and a cow (B. taurus) reveal similarity with that of Candidatus Anaplasma boleense strain (GenBank accession no.: KX987335). Sequence analyses of the partial gene fragments of major surface protein (msp4) gene from two deer (R. timorensis) and a monitor lizard (Varanus salvator) show the detection of a strain highly similar (99%) to that of A. phagocytophilum strain ZJ-China (EU008082). The findings in this study show the occurrence of various Anaplasma species including those newly reported species in Malaysian domestic and wildlife animals. The role of these animals as reservoirs/maintenance hosts for Anaplasma infection are yet to be determined.

Matched MeSH terms: Ehrlichia/genetics
Fulltext Bacterial community in Haemaphysalis ticks of domesticated animals from the Orang Asli communities in Malaysia

Khoo JJ, Chen F, Kho KL, Ahmad Shanizza AI, Lim FS, Tan KK, et al.

Ticks Tick Borne Dis, 2016 07;7(5):929-937.
PMID: 27132518 DOI: 10.1016/j.ttbdis.2016.04.013

Ticks are vectors in the transmission of many important infectious diseases in human and animals. Ticks can be readily found in the semi-forested areas such as the settlements of the indigenous people in Malaysia, the Orang Asli. There is still minimal information available on the bacterial agents associated with ticks found in Malaysia. We performed a survey of the bacterial communities associated with ticks collected from domestic animals found in two Orang Asli villages in Malaysia. We collected 62 ticks, microscopically and molecularly identified as related to Haemaphysalis wellingtoni, Haemaphysalis hystricis and Haemaphysalis bispinosa. Bacterial 16s rRNA hypervariable region (V6) amplicon libraries prepared from the tick samples were sequenced on the Ion Torrent PGM platform. We detected a total of 392 possible bacterial genera after pooling and sequencing 20 samples, indicating a diverse bacterial community profile. Dominant taxa include the potential tick endosymbiont, Coxiella. Other dominant taxa include the tick-associated pathogen, Rickettsia, and environmental bacteria such as Bacillus, Mycobacterium, Sphingomonas and Pseudomonas. Other known tick-associated bacteria were also detected, including Anaplasma, Ehrlichia, Rickettsiella and Wolbachia, albeit at very low abundance. Specific PCR was performed on selected samples to identify Rickettsia and Coxiella. Sequence of Rickettsia felis, which causes spotted fever in human and cats, was identified in one sample. Coxiella endosymbionts were detected in three samples. This study provides the baseline knowledge of the microbiome of ticks in Malaysia, focusing on tick-associated bacteria affecting the Orang Asli communities. The role of the herein found Coxiella and Rickettsia in tick physiology or disease transmission merits further investigation.

Matched MeSH terms: Ehrlichia/genetics
Fulltext Molecular detection of pathogens in ticks and fleas collected from companion dogs and cats in East and Southeast Asia

Nguyen VL, Colella V, Greco G, Fang F, Nurcahyo W, Hadi UK, et al.

Parasit Vectors, 2020 Aug 15;13(1):420.
PMID: 32799914 DOI: 10.1186/s13071-020-04288-8

BACKGROUND: Ticks and fleas are considered amongst the most important arthropod vectors of medical and veterinary concern due to their ability to transmit pathogens to a range of animal species including dogs, cats and humans. By sharing a common environment with humans, companion animal-associated parasitic arthropods may potentially transmit zoonotic vector-borne pathogens (VBPs). This study aimed to molecularly detect pathogens from ticks and fleas from companion dogs and cats in East and Southeast Asia.
METHODS: A total of 392 ticks and 248 fleas were collected from 401 infested animals (i.e. 271 dogs and 130 cats) from China, Taiwan, Indonesia, Malaysia, Singapore, Thailand, the Philippines and Vietnam, and molecularly screened for the presence of pathogens. Ticks were tested for Rickettsia spp., Anaplasma spp., Ehrlichia spp., Babesia spp. and Hepatozoon spp. while fleas were screened for the presence of Rickettsia spp. and Bartonella spp.
RESULT: Of the 392 ticks tested, 37 (9.4%) scored positive for at least one pathogen with Hepatozoon canis being the most prevalent (5.4%), followed by Ehrlichia canis (1.8%), Babesia vogeli (1%), Anaplasma platys (0.8%) and Rickettsia spp. (1%) [including Rickettsia sp. (0.5%), Rickettsia asembonensis (0.3%) and Rickettsia felis (0.3%)]. Out of 248 fleas tested, 106 (42.7%) were harboring at least one pathogen with R. felis being the most common (19.4%), followed by Bartonella spp. (16.5%), Rickettsia asembonensis (10.9%) and "Candidatus Rickettsia senegalensis" (0.4%). Furthermore, 35 Rhipicephalus sanguineus ticks were subjected to phylogenetic analysis, of which 34 ticks belonged to the tropical and only one belonged to the temperate lineage (Rh. sanguineus (sensu stricto)).
CONCLUSION: Our data reveals the circulation of different VBPs in ticks and fleas of dogs and cats from Asia, including zoonotic agents, which may represent a potential risk to animal and human health.

Matched MeSH terms: Ehrlichia/genetics