Evidence of Influenza A Virus Infection in Cynomolgus Macaques, Thailand

Little is known about the ecology of influenza A virus (IAV) in nonhuman primates (NHPs). We conducted active surveillance of IAV among 672 cynomolgus macaques (Macaca fascicularis) living in 27 free-ranging colonies in Thailand between March and November 2019. A hemagglutination inhibition (HI) assay was employed as the screening test against 16 subtypes of avian influenza virus (AIV) and two strains of the H1 subtype of human influenza virus. The serum samples with HI titers ≥20 were further confirmed by microneutralization (MN) assay. Real-time RT-PCR assay was performed to detect the conserved region of the influenza matrix (M) gene. The seropositive rate for subtypes of IAV, including AIV H1 (1.6%, 11/672), AIV H2 (15.2%, 102/672), AIV H3 (0.3%, 2/672), AIV H9 (3.4%, 23/672), and human H1 (NP-045) (0.9%, 6/672), was demonstrated. We also found antibody against more than one subtype of IAV in 15 out of 128 positive tested sera (11.7%). Moreover, influenza genome could be detected in 1 out of 245 pool swab samples (0.41%). Evidence of IAV infection presented here emphasizes the role of NHPs in the ecology of the virus. Our findings highlight the need to further conduct a continuous active surveillance program in NHP populations.

Zoonotic pathogens survey in free-living long-tailed macaques in Thailand

Long-tailed macaques (Macaca fascicularis) are known to harbour a variety of infectious pathogens, including zoonotic species. Long-tailed macaques and humans coexist in Thailand, which creates potential for interspecies pathogen transmission. This study was conducted to assess the presence of B virus, Mycobacterium spp., simian foamy virus (SFV), hepatitis B virus (HBV), and Plasmodium spp. in 649 free-living Thai long-tailed macaques through polymerase-chain reaction. DNA of SFV (56.5%), HBV (0.3%), and Plasmodium spp. (2.2%) was detected in these macaques, whereas DNA of B virus and Mycobacterium spp. was absent. SFV infection in long-tailed macaques is broadly distributed in Thailand and is correlated with age. The HBV sequences in this study were similar to HBV sequences from orangutans. Plasmodium spp. DNA was identified as P. inui. Collectively, our results indicate that macaques can carry zoonotic pathogens, which have a public health impact. Surveillance and awareness of pathogen transmission between monkeys and humans are important.

Molecular Detection of Bartonella quintana among Long-Tailed Macaques (Macaca fascicularis) in Thailand

Bartonella quintana is a zoonotic pathogen with a worldwide distribution. Humans and non-human primates are considered to be natural reservoir hosts for B. quintana. However, information on the molecular epidemiology of this organism is very limited in regard to long-tailed macaques (Macaca fascicularis) in Thailand. Therefore, this study aimed to investigate the occurrence and genetic diversity of Bartonella spp. among long-tailed macaques in Thailand. In total, 856 blood samples were collected from long-tailed macaques in Thailand. All specimens were screened for Bartonella spp. using a polymerase chain reaction (PCR) assay targeting the 16S rRNA, gltA and ftsZ genes. All positive samples were further analyzed based on nucleotide sequencing, phylogenetic analysis and multiple sequence alignment analysis. Only one macaque showed a positive result in the PCR assays based on the 16S rRNA, gltA and ftsZ genes. Nucleotide sequencing and phylogenetic analysis revealed that the obtained sequences were closely related to B. quintana previously detected in non-human primates. Single-nucleotide polymorphisms (SNPs) were detected in the gltA and ftsZ gene sequences. This study revealed that long-tailed macaques in Thailand carried B. quintana. Despite the low infection rate detected, long-tailed macaques may be a reservoir of B. quintana.

Detection and genetic characterization of "Candidatus Mycoplasma haemomacaque" infection among long-tailed macaques (Macaca fascicularis) in Thailand using broad-range nested polymerase chain reaction assay

Background and Aim

Hemoplasmas are defined as small, epicellular parasitic bacteria that can infect the red blood cells of several mammalian species. Diseases caused by these bacteria range from asymptomatic infections to acute hemolytic anemia. However, data on hemoplasmas in non-human primates in Thailand remain to be limited. Therefore, this study aims to determine the occurrence and genetic diversity of hemoplasmas among long-tailed macaques in Thailand.

Materials and Methods

Blood samples were collected from 339 long-tailed macaques in three provinces of Thailand. DNA was then extracted from the blood samples and tested for hemoplasma using broad-range nested polymerase chain reaction (PCR) based on the 16S rRNA gene. PCR-positive samples were sequenced, and phylogenetic analysis for species identification was conducted.

Results

In total, 38 (11.2%) out of the 339 samples were found to be positive for hemoplasmas, based on the broad-range nested PCR assay of the 16S rRNA gene. The 16S rRNA sequences of Mycoplasma spp. were highly similar (98-99% identity) to "Candidatus Mycoplasma haemomacaque." Furthermore, phylogenetic analysis using maximum likelihood demonstrated that the sequences were located in the same cluster of "Ca. M. haemomacaque."

Conclusion

The detection of hemoplasmas among long-tailed macaques in Thailand is reported. Genetic characterization confirmed that these hemoplasmas are closely related to "Ca. M. haemomacaque." These results indicate that long-tailed macaques in several locations in Thailand may be infected and serve as reservoirs for this parasite.

Molecular characterization of Hepatozoon felis in Rhipicephalus sanguineus ticks infested on captive lions (Panthera leo)

Hepatozoon spp. are protozoan parasites that infect a wide range of domestic and wild animals. The infection occurs by ingestion of an infected tick. This study was carried out to detect and characterize Hepatozoon spp. in ticks collected from captive lions (Panthera leo) in Thailand based on the partial 18S rRNA gene sequence. A total of 30 ticks were collected and identified as Rhipicephalus sanguineus. The collected ticks were separated into 10 tick pools by sex and life stages. Of the 10 tick pools examined, only one (10%) was found to be infected with the Hepatozoon species. Sequencing and phylogenetic analysis showed a clustering of the partial 18S rRNA gene sequence like that of H. felis from the GenBank database. This is the first report of H. felis in R. sanguineus ticks collected from captive lions in Thailand. Our results indicated that R. sanguineus may be a possible vector of feline Hepatozoon in Thailand.

Dengue, Japanese encephalitis and Chikungunya virus antibody prevalence among captive monkey (Macaca nemestrina) colonies of Northern Thailand

The potential of macaque Macaca nemestrina leonina in Thailand to be infected by endemic arboviruses was assessed. The prevalence of antibodies of three arboviruses actively circulating in Thailand was determined by Plaque Reduction Neutralization assay procedures using samples from captive colonies in Northern Thailand. Out of 38 macaques, 9 (24%) presented reacting antibodies against dengue virus, 5 (13%) against Japanese encephalitis virus, and 4 (10%) against Chikungunya virus. Our results indicate that the northern pig-tailed macaque in Thailand can be infected by these arboviruses, inferring therefore that their virus specific vectors have bitten them. Given that, northern pig-tailed macaque represents an abundant population, living in close range to human or in peridomestic setting, they could play a role as potential reservoir host for arboviruses circulating in Thailand.