Genetic characterization and risk factors for feline hemoplasma infection in semi-domesticated cats in Bangkok, Thailand

Abstract

Background and aim: Stray cats are a reservoir for various zoonotic diseases relevant to public health in Thailand. The vector-borne infection, hemoplasmosis, also known as infectious anemia, is one such disease carried by domestic and wild felids. This study focuses on molecular characterization and phylogenetic analysis of hemoplasma in semi-domesticated cats in Bangkok, Thailand.

Materials and methods: In total, 473 blood samples were collected from 53 temple communities in 34 metropolitan districts and assayed using polymerase chain reaction (PCR) to amplify partial 16S rRNA genes for hemoplasma detection. Risk factors for hemoplasma infection (gender, age, free-roaming, and ectoparasite exposure) were analyzed using Chi-square tests, logistic regression, and odds ratios (OR) with 95% confidence intervals (95% CI) using R software (version 3.6.1). A phylogenetic tree was established from genetic characterization of hemoplasmas.

Results: In total, 180 samples (38.05%) were positive for hemoplasma. Of half of the positive sequenced samples, 83.33% were infected with Candidatus Mycoplasma haemominutum (CMhm), 13.33% with Mycoplasma haemofelis (Mhf), and 3.33% with Candidatus Mycoplasma turicensis (CMt). Cats over 5 years old were more likely to be infected than younger cats (p<0.005, OR=3.8, 95% CI=1.64-4.78). Cats were diagnosed as positive based on PCR assays in 97% (33/34) of districts surveyed. The phylogenetic tree showed two majority clusters with three clades of feline hemotropic mycoplasma.

Conclusions: Overall, the survey shows the prevalence (38.05%) and distribution of feline hemoplasma in semi-domesticated cats. This information will contribute to effective prevention and control strategies to minimize infections by feline vector-borne pathogens in Thailand.

Keywords: Thailand; hemoplasma; semi-domesticated cat; vector-borne diseases.

Figure-1

Map of study area in Bangkok. The highlighting 34 selected districts (yellow-colored areas identified as infected with the pathogen and black-colored area indicates no detected of infection) (https://upload.wikimedia.org/wikipedia/commons/4/4f/Thailand_Bangkok_location_map.png).

Figure-2

Phylogenetic tree of feline hemoplasma based on the nucleotide sequences of a 595 bp fragment of 16S rRNA gene using the maximum likelihood method. Numbers at nodes represent percentage occurrences of clades based on 1000 bootstrap replications of data. The CMhm, Mhf, and CMt sequences generated in the present study are in bold and indicated by black diamond (♦), square (◼), and circle (●) symbols, respectively.