Gastro-intestinal parasites in two subspecies of toque macaque (Macaca sinica) in Sri Lanka and their zoonotic potential

Zoonotic pathogens in wild Asian primates: a systematic review highlighting research gaps

Introduction

Ongoing global changes, including natural land conversion for agriculture and urbanization, modify the dynamics of human-primate contacts, resulting in increased zoonotic risks. Although Asia shelters high primate diversity and experiences rapid expansion of human-primate contact zones, there remains little documentation regarding zoonotic surveillance in the primates of this region.

Methods

Using the PRISMA guidelines, we conducted a systematic review to compile an inventory of zoonotic pathogens detected in wild Asian primates, while highlighting the coverage of primate species, countries, and pathogen groups surveyed, as well as the diagnostic methods used across the studies. Moreover, we compared the species richness of pathogens harbored by primates across diverse types of habitats classified according to their degree of anthropization (i.e., urban vs. rural vs. forest habitats).

Results and discussion

Searches of Scopus, PubMed, and the Global Mammal Parasite Database yielded 152 articles on 39 primate species. We inventoried 183 pathogens, including 63 helminthic gastrointestinal parasites, two blood-borne parasites, 42 protozoa, 45 viruses, 30 bacteria, and one fungus. Considering each study as a sample, species accumulation curves revealed no significant differences in specific richness between habitat types for any of the pathogen groups analyzed. This is likely due to the insufficient sampling effort (i.e., a limited number of studies), which prevents drawing conclusive findings. This systematic review identified several publication biases, particularly the uneven representation of host species and pathogen groups studied, as well as a lack of use of generic diagnostic methods. Addressing these gaps necessitates a multidisciplinary strategy framed in a One Health approach, which may facilitate a broader inventory of pathogens and ultimately limit the risk of cross-species transmission at the human-primate interface. Strengthening the zoonotic surveillance in primates of this region could be realized notably through the application of more comprehensive diagnostic techniques such as broad-spectrum analyses without a priori selection.

First Molecular Identification of Ancylostoma Species in Dogs in a Rural Tea Estate Community in Sri Lanka and the Detection of Other Zoonotic Gastro-intestinal Parasites

PURPOSE

Ancylostoma spp. causing canine hookworm infections are distributed worldwide with a high prevalence in the South Asian region. Here, we report the first molecular identification of the canine hookworm infecting the dogs in Sri Lanka.

METHOD

Fresh faecal samples were collected from free-roaming dogs in tea estate communities in Talawakelle, processed and microscopically analysed for gastro-intestinal parasites. The common dog hookworm Ancylostoma sp. was further investigated using molecular diagnostic tools including PCR, sequencing, and phylogenetic analyses.

RESULTS

Of the individual dogs sampled, 97.0% (97/100) were positive for GI parasites, identifying 14 species, all of which were zoonotic. Entamoeba sp. (58.0% (58/100)) was the most prevalent infection and Ancylostoma sp. (45.0% (45/100)) was the most prevalent helminth infection. Overall, helminth prevalence was higher in female dogs (92.5% (37/40)) than male dogs (73.3% (44/60)), potentially due to immune suppression during pregnancy and lactation. The prevalence and burden of Toxocara canis was higher in puppies (≤ 1 year) (68.8%(11/16); Chi-square test; χ² = 20.912, p < 0.001 and FEC = 5.91; Mann-Whitney U test; p < 0.001), possibly due to vertical trans-mammary or trans-placental transmission of infective larvae. This study also presents the first record of Hymenolepis sp. from dogs in Sri Lanka. Ancylostoma sp. was molecularly confirmed as A. caninum.

CONCLUSION

The local variant of A. caninum was phylogenetically unique and showed 99.2% similarity to that from India. The high prevalence of zoonotic GI parasites with public health significance highlights the importance of improving community well-being, veterinary care for dogs, and public awareness on zoonoses.

Effect of urbanization on zoonotic gastrointestinal parasite prevalence in endemic toque macaque (Macaca sinica) from different climatic zones in Sri Lanka

Understanding variations in host-parasite relationships with urbanization is vital for both, public health management and conservation of endemic animals with high anthropogenic interactions. Toque macaques (Macaca sinica) are such endemic old-world monkeys in Sri Lanka. Three macaque sub species inhabit the main climatic zones of the island; M . s. sinica , M . s. aurifrons and M . s. opisthomelas inhabit the dry zone, wet zone, and montane regions of the island, respectively. This study aimed to examine parasite prevalence in this host in association with urbanization. A total of 180 fecal samples were collected from the three sub species of toque macaques inhabiting the main climatic zones (dry, wet, and montane) in Sri Lanka; 20 samples each were collected from urban, suburban, and wild populations representing each climatic zone. Twenty gastrointestinal (GI) parasite genera types i.e. five types of protozoan cysts, two types of trematode ova, four types of cestode ova, eight types of nematode ova, and a single type of acanthocephalan ova were identified. The overall prevalence of parasites was 62% (112/180) with the highest prevalence of Strongyloides infection. In all three sub species, toque macaque populations with proximity to human settlements, including urban and suburban populations, manifested a greater GI parasitic prevalence, mean ova/cyst counts and species richness, compared to their wild counterparts. Importantly, records of five parasite types in toques in Sri Lanka are reported for the first time, while Moniliformis type was reported as a first record in free ranging macaques, globally. This study clearly demonstrated that human contact and habitat modification may influence patterns of parasitic infections in macaques. As most of the parasite types identified manifest zoonotic potential, with public health implications, close associations of macaques may cause a threat to human well-being.

Preliminary assessment of gastrointestinal parasites of the sun-tailed monkey (Allochrocebus solatus) in a semi-free-ranging colony

BACKGROUND

The occurrence of gastrointestinal parasites in the sun-tailed monkey (Allochrocebus solatus) at the CIRMF primatology center is unknown. We, therefore, assessed the presence and richness (number of different parasite taxa) of gastrointestinal parasites in a semi-free-ranging colony of A. solatus.

METHODS

A total of 46 fecal samples were screened using a modified McMaster technique for fecal egg counts.

RESULTS

In the 46 samples collected, seven taxa of gastrointestinal parasites, including protozoa and nematodes were identified. The most prevalent parasite was strongyles parasites (98%), followed by Trichuris spp. (72%), Strongyloides spp. (67%) and Entamoeba coli (65%). Balantioides coli (33%), Endolimax nana (25%), and Spirurid eggs (26%) were only found in a minority of the animals.

CONCLUSIONS

This study contributes new host records of gastrointestinal parasites in semi-free-ranging A. solatus and highlights the need to investigate the health of this species and implement proper precautions in the management of this colony.

Case Report: Molecular and Pathological Investigations of Zoonotic Anatrichosoma Spp.-Induced Ulcerative Pododermatitis in a Domestic Cat in Thailand

Anatrichosoma spp. is a group of trichuroid nematodes that mainly infect non-human primates and domestic cats. The lifecycle of these nematodes remains unclear. In non-human primates, Anatrichosoma spp. were found in the nasal cavity. However, ulcerative dermatitis has been reported in infected cats. An adult, intact, female domestic short-haired cat was presented with ulcerative pododermatitis of all limbs. Punch biopsy was performed at the edge of the ulcerative wound for histopathological investigation and showed necrosis and infiltration of inflammatory cells around the nematode-like lesion. Eggs with Capillaria-like characteristics were present. Tissue sections were subjected to DNA extraction and PCR targeting 18S rRNA, using primers designed from Anatrichosoma 18S rRNA. The phylogenetic tree revealed that DNA obtained from the lesion of the domestic cat was grouped with Anatrichosoma spp. from the olive glass mouse (Abothirx olivacea), Capillaria plica and Eucoleus aerophilus, both from the red fox (Vulpes Vulpes). The study is the first report of feline anatrichosomiasis in Thailand, and we present both pathological findings and molecular evidence. The cat was successfully treated with emodepsine/praziquantel. The skin lesion recovered within 3 days after anthelmintic treatment. Because Anatrichosoma spp. have been reported in humans, the zoonotic potential of this parasite should be considered.