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.

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.

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.

Hemotropic mycoplasmas, also known as hemoplasmas, are parasitic bacteria that infect red blood cells, potentially leading to varying degrees of anemia across numerous mammalian species, including nonhuman primates. The present study aims to investigate the prevalence of hemoplasma infection and identify the species involved among free‐ranging Assamese macaques (Macaca assamensis) inhabiting northern Thailand. A total of 133 blood samples were collected from Assamese macaques in Chiang Rai province, Thailand, and subjected to screening for hemoplasma infection utilizing nested PCR amplification targeting the 16S rRNA gene. Positive samples were subsequently analyzed through nucleotide sequencing and phylogenetic analysis for putative species identification. Current study results revealed that 17.3% (23/133; 95% CI 11.29‐24.81) of Assamese macaques tested positive for hemoplasma infection using the nested PCR assay. Partial 16S rRNA sequences derived from hemoplasma isolates in Assamese macaques exhibited 99% homology, forming a cluster within the same phylogenetic clade as “Candidatus Mycoplasma haematomacacae,” previously identified in long‐tailed macaques, rhesus macaques, and Japanese macaques. These findings suggest the presence of “Ca. M. haematomacacae” not only in long‐tailed macaques and rhesus macaques but also in Assamese macaques in Thailand. To our knowledge, this marks the first molecular detection of “Ca. M. haematomacacae” in Assamese macaques in Thailand. These results hold significance as they enhance our understanding of hemoplasma infection distribution among macaque populations in Thailand.

Zoonotic malaria, caused by simian Plasmodium spp., poses a major public health challenge in Southeast Asia, including Thailand, where long‐tailed macaques ( Macaca fascicularis ) serve as natural reservoirs. This study investigated the molecular prevalence and species identification of zoonotic simian Plasmodium spp. in macaques from four provinces in Southern Thailand: Phetchaburi, Satun, Phang Nga, and Surat Thani. A total of 310 blood samples were collected between May 2023 and June 2024 and analyzed using nested and seminested polymerase chain reaction (PCR) techniques targeting the 18S rRNA gene. Sequencing analyses confirmed the presence of zoonotic Plasmodium species. Overall, 11.3% (35/310; 95% CI: 7.9–15.3) of the macaques tested positive, with Plasmodium inui being the most prevalent species at 9.4% (29/310), followed by Plasmodium knowlesi and Plasmodium cynomolgi , each at 0.9% (3/310). The highest prevalence was observed in Surat Thani at 18% (18/100). These findings underscore the zoonotic potential of simian malaria and its geographic distribution in Southern Thailand, which may be associated with the significant increase in macaque populations and their expanding habitat overlap with human communities. In conclusion, this study highlights the major role of long‐tailed macaques as reservoirs for zoonotic Plasmodium spp. Enhanced surveillance and community awareness are crucial for mitigating cross‐species transmission and improving malaria control.

Protected national parks continue to face increased pressure from the expansion of human–wildlife interface zones, where habitat encroachment promotes human–wildlife contact and zoonotic disease transmission. Gastrointestinal parasites (GIPs) are a significant health issue in wild Asian elephants (Elephas maximus), affecting their fitness, survival, and potential for cross-species transmission. This study aimed to investigate the prevalence of GIPs among wild elephants at Khao Sip Ha Chan National Park in eastern Thailand. Direct smear, formalin-ethyl acetate sedimentation, flotation, and McMaster egg per gram (EPG) counting were used to examine 135 fecal samples from three populations. The findings showed that nematodes (Strongyle-type and Strongyloides spp.) and trematodes (Paramphistomum spp. and Fascioloides jacksoni) were identified. All samples were positive for at least one parasite species, and 84.4% were affected by mixed infections. The prevalence of Strongyle-type and Strongyloides spp. varied significantly among the studied populations, but Paramphistomum spp. had a moderate prevalence, and Fascioloides jacksoni had a low prevalence. The high parasite burden could be explained by environmental factors, host density, and movement patterns influencing parasite transmission, and these factors should be further investigated. These findings provide crucial baseline data and underscore the need for integrated parasite surveillance, alongside long-term conservation and future research.