Occurrence of gastrointestinal (GI) parasites in captive Olive Baboon and Common Langur in Bangladesh

Non-human primates (NHPs) serve as necessary reservoir hosts of parasites that create diseases to human. A close interaction between human and NHP can make a pathway for transmission of zoonotic diseases. To prevent zoonotic infection of zoo keepers, park visitors as well as keeping the captive NHPs in healthy state, it is necessary to carry out regular parasitological examination and treatment. A total of 72 fecal samples of Olive Baboon (n = 39) and Common Langur (n = 33) irrespective of their age and sex were collected from two zoological gardens of Bangladesh. Eggs and oocysts of seven gastrointestinal (GI) parasites were observed and identified in samples of both host species. The prevalence of GI parasites recorded was 100%. In case of Olive Baboon, the protozoan prevalence was higher (53.83%) than that of helminths, but opposite scenario was seen in case of Common Langur. Besides, higher intensity of coccidian oocysts in both hosts was recorded in the study.

Non-human primates (NHPs) represent one of the most interesting as well as important groups among zoo animals for their valuable role in public recreation (Agoramoorthy and Hsu 2005). NHPs in captivity often live in small to large groups characterized by frequent social interactions, which facilitate parasite transmission between individuals making them vulnerable to gastrointestinal (GI) parasitic infections (Stoner 1996). Severe GI parasitic infections can lead to serious damages such as, tissue damage, blood loss, congenital malformations and eventually death (Verweij et al. 2003). Many studies reported the occurrence of GI parasites in wild and captive NHPs worldwide (Karere et al. 2002;Tachibana et al. 2009;Li et al. 2015). Olive Baboon (Papio anubis) is frequently studied in different countries (Bezjian et al. 2008); on the contrary, studies on endoparasitic infections of Common Langur (Semnopithecus entellus) are still on the baseline. To date, very few data is available about the prevalence of GI parasites in captive NHPs in zoos of Bangladesh (Raja et al. 2014;Khatun et al. 2014;Tabasshum et al. 2018;Karim et al. 2020).
The present study was performed to investigate the occurrence of GI parasites in captive Olive Baboon and Common Langur present in two zoological gardens of Bangladesh. Moreover, systematic studies on GI parasitic infections among captive NHPs present in the zoos of Bangladesh are demanded for the proper appliance of anthelmintic drug administration as well as the safety management of the animal keepers and visitors.
The current study showed that all fecal samples were positive with at least one protozoan or helminth parasite. We identified eggs and oocysts of seven GI parasites consisting of one protozoan (Coccidia spp.) and six helminths of which, two cestodes (Hymenolepis spp. and Spirometra spp.) and four nematodes (Ascaris spp., Toxocara spp., Trichuris spp. and hookworms) in both host species (Fig. 1) We found dominance of helminths prevalence over protozoan parasites in Common Langur. 100% prevalence was recorded for Spirometra spp., Ascaris spp., Toxocara spp. and hookworms and the lowest prevalence was recorded for Trichuris spp. (9.09%) ( Table 2). But the maximum intensity of protozoan parasites (here, Coccidia spp., intensity 31.95) was identified in Common Langur, which is also a similar case for Olive Baboons. The least intensity in Common Langur was calculated for Toxocara spp. (0.18) ( Table 2).
The present study reported seven similar GI parasites recorded in both host species with overall 100% prevalence. Literature records showed various prevalence among NHPs in different countries. For example, Li et al. (2015) reported 26.51% prevalence of GI parasites in 24 zoos of China; Bichi et al. (2016) found 26.09% prevalence in Kano State Zoological Garden, Nigeria; Aviruppola et al. (2016) detected 61.1% prevalence in Dehiwala National Zoological Gardens, Sri Lanka. On the contrary, the prevalence of GI parasites in present study was much higher than those recorded previously. The host species, Olive Baboon and Common Langur were housed in adjacent cages and provided the same food, which makes a great   possibility to contaminate each other. Additionally, it came to our knowledge during the survey that anthelmintic drug administration among the zoos is irregularly maintained. We found oocysts of only one protozoan parasite Coccidia spp. with high prevalence and intensity in both hosts. The high rate might occur due to their simple life cycle, lack of intermediate host and favorable climatic condition (Kheysin 2013). Among nematodes, Ascaris spp. was the most prevalent parasite with 46.15% and 100% in Olive Baboon and Common Langur respectively (Tables 1 and 2). Previous studies of Ocaido et al. (2003), Hope et al. (2004) and Larbi et al. (2020) reported Ascaris spp. in Olive Baboon; and Parmar et al. (2012) in Common Langur. Among these studies, Hope et al. (2004) found 78.6% prevalence of this parasite which is higher than other parasites.
Spirometra spp. and Toxocara spp. are generally found in carnivores (Ghoke 2012;Javaregowda 2016). Liza et al. (2020aLiza et al. ( , 2020b found these two parasites in captive Asiatic black bear, Bengal tiger and African lion in different zoological gardens of Bangladesh. We also detected these helminths in the present study (Tables 1  and 2). One of the reasons behind their presence in non-human primates can be the strong resistance and longevity of infective eggs in the environment that ensure their transmission to another host. Again both the zoos, selected as study areas, have one or two carnivore cages nearby NHP cages. The walls and floors of those cages are built with cement which aid in clutching parasite eggs and may promote infections.
Previous studies showed the presence of Trichuris sp., Ascaris sp., and Hymenolepis sp. (including unidentified protozoa, nematode and hookworm) in Olive Baboon; and Trichuris sp., Ascaris sp., Spirometra sp. and unknown hookworms in Common Langur similar to current study (Table 3). Among these parasites, Trichuris sp. was the most reported nematode in both hosts (Table 3). The study of Raja et al. (2014) in Dhaka zoo of Bangladesh found Trichostrongylus sp. and Balantidium coli in Olive Baboon; and Balantidium coli and Capillaria sp. in Common Langur, which we did not observe in the current study. We collected samples randomly from both Dhaka and Rajshahi zoo, two different zoos with different geographic conditions unlike Raja et al. (2014). This may result the variation in parasites from the previous study. Khatun et al. (2014) also conducted a similar study in Rangpur zoo of Bangladesh, but did not report any parasites in Olive Baboon.
Different studies found diverse parasites in Olive Baboon and Common Langur that have not been observed during our study. For example, Oesophagostamum sp. was reported in the studies of Murray et al. (2000), Ocaido et al. (2003), Legesse and Erko (2004), Bezjian et al. (2008) and Ryan et al. (2012) in Olive Baboon; while the studies of Gunasekera et al. (2012)   This may be different from our study due to different geographic location, climatic condition and varied susceptibility of hosts to the parasites. These parasites can affect health of the primates in captivity, increasing their stress level and consequently can claim their lives. The presence of zoonotic parasites, like-Trichuris spp., Ancylostoma spp. in the host species can affect the health of handlers and visitors to the zoos if not controlled (Adejinmi and Ayinmode 2008;Monteiro et al. 2007). The present result with high prevalence of protozoan and helminth parasite necessitates initiating an optimization of the treatment protocol in both zoological gardens.

Methods
This study was conducted at two zoological gardens of Bangladesh (Bangladesh National Zoo, Dhaka and Shaheed A.H.M. Central Park and Zoo, Rajshahi) from July 2017 to February 2018. The fecal samples were collected from two species of captive nonhuman primates (Olive Baboon and Common Langur) from both zoos with permission of the authority. A total of 72 fresh fecal samples of Olive Baboon (n = 39) and Common Langur (n = 33) were collected from the cage floor with the help of caretakers following simple random sampling (Yates et al. 2008) (details in Table 4).
All individuals of the host species seemed healthy during sample collection and were housed in small to large cages with available water supply. Generally, the cages of NHPs were cuboid in shape in both zoos; average height was about 4 m. The roof of the cages was covered by iron sheets, and the floor was made of concrete. Wire net was used around the cage for safety. The procedures of sample processing, identification, counting and calculation of eggs/ cysts/ oocysts of GI parasites are given as follows: After collection, the samples were placed in plastic jars containing 10% formalin, and sealed tightly to avoid contamination. Later, samples were stored in the refrigerator at 4°C for not more than seven days in Parasitology laboratory of Department of Zoology, University of Dhaka.
The sample screening was performed following Formol-Ether Concentration Technique (Cheesbrough 1987). Observation of eggs/ cysts/ oocysts and larva has been performed with the help of compound microscope using 10X and 40X objective lenses.
Identification of parasite's eggs/ cysts/ oocysts was confirmed on the basis of morphological descriptions, life cycles and pictures published by Chatterjee (1980), Cheng (1997), Soulsby (1982) and Schmidt and Roberts (1996). We found hookworm eggs in all samples but they were difficult to identify to genus or species level.