Biswal Chichilichi Chitta Ranjan Pradhan Lakshman Kumar Babu Niranjan Sahoo Mitra Ranjan Panda Sumanta Kumar Mishra Kumaresh Behera Abinash Das Ananta Hembram Vol 9(2), 302-310 DOI- http://dx.doi.org/10.5455/ijlr.20180918101740
The study was conducted to evaluate the incidence of endoparasitic infestation in free ranging and captive Asian elephants in Odisha covering three seasons namely, summer (April-June), rainy (July-September) and winter (November-January). The locations were Chandaka Wildlife Sanctuary, Khordha; Satkosia Wildlife Sanctuary, Angul; Similipal Biosphere Reserve, Mayurbhanj for free-ranging, and Nandankanan Zoological Park, Bhubaneswar for captive elephants. Faecal samples were analysed by direct smear method, sedimentation technique and floatation method. The captive location showed a markedly lower endoparasitic infestation rate than any of the free-range locations, in every season; the differences being significant (P≤0.01) in summer and rainy only. Thus, as regards to the seasonal influence, for each of the free-range and captive locations, the highest rate of infestation was observed in summer followed by rainy and winter.
Asian elephants, the majestic animals, are now-a-days imperiled to several adversities affecting their very survivability and longevity, which include increased parasitic infestation as well. Parasitic infestations in wild animals act as a potential stressor afflicting their health status. Parasitic study can serve as an effective, practical, non-invasive early warning system for the health of individual hosts, host populations and the ecosystems of which they are a part, because environmental changes impact upon both hosts and their parasites (Lafferty, 1997; Marcogliese, 2005). Parasitic study in wild animals is often a neglected area, though it serves as an important tool of conservation science from the perspective that, ecosystem and animal health are linked and hence, monitoring parasites can be an indicator of both (Lafferty, 1997; Marcogliese, 2005; Howells et al., 2011). This study was conducted to ascertain the incidence of endoparasites from the faecal samples and the influence of seasonality in both free-ranging and captive Asian elephants.
Materials and Methods
Study Locations and Duration
The field study was carried out in both geographically distinct free-range areas and captive locations in Odisha, India involving Chandaka Wildlife Sanctuary (WLS), Bhubaneswar, Khordha; Satkosia Wildlife Sanctuary, Angul and Similipal Biosphere Reserve (BR), Mayurbhanj for free-ranging Asian elephants, and in the Nandankanan Zoological Park (ZP), Bhubaneswar, Khordha for captive ones. The three naturally classified seasons namely, summer (April-June), rainy (July-September) and winter (November-January) were covered during the trial.
Collection of Sample
Core samples were collected within few hours of defecation from faecal boli of elephants to reduce contamination by soil helminthes, and stored in 10% formalin. Since parasite eggs may not be evenly distributed among the boli of a dung pile or even within a bolus, each sample comprised of separate portions from the surface and the interior of different boli of a dung pile. Due care was taken to prevent cross-contamination among the samples by putting on gloves during sample collection and changing them after each collection. The age and sex of the elephants were unknown for samples collected from free range. The samples were collected labeling with place, date and time of collection.
Direct Smear Method
Samples of 10-15 g were mixed thoroughly in a clean glass mortar and pestle by adding little amount of water and poured through a sieve of mess size 500-800 micrometer to remove debris and large lumps. The strained fluid was collected in a beaker. The sieve was rinsed with water and the debris left on the screen was discarded. A few drop of strained fluid was placed on a slide with removal of any fibers or particles present followed by placing a cover slip on it while avoiding any air bubble. The slide was investigated using a magnification of 10X and 40X.
The strained suspension was transferred to centrifuge tube and centrifuged at 1500 rpm for 2 minutes. The sediment was mixed well after discarding the supernatant. A small quantity of it was taken and mixed with a drop of water on the slide. A cover slip was applied and observed under low power objective of the microscope to identify the parasitic ova present, through their morphological characteristics (Bowman, 1999).
About 5 g of faeces was taken in a glass mortar and pestle and small quantity of saturated flotation solution (magnesium sulphate/ zinc sulphate/ sugar solution) was added and mixed well. Suspension was strained to remove the debris and was centrifuged at 1500 revolutions per minute (rpm) for 2-3 minutes. The surface layer was examined under low power microscope by covering with a cover slip. The presence of eggs was identified through their morphological characteristics (Bowman, 1999).
The data generated in the experiment was statistically analyzed using the Statistical Package for the Social Sciences (SPSS) Version 20.0. For comparison of groups, ANOVA procedure and Duncan’s multiple range tests were used (Steel and Torrie, 1980). Pearson’s Chi- square test was conducted to analyze the seasonal and locational differences in parasitic incidence.
Results and Discussion
Infestation Rate (%)
A comparison of endoparasitic infestation rates, denoted by percent of samples positive for parasitic ova, among different locations and seasons are presented in Table 1.
Table 1: Endoparasitic infestation rate in different locations and seasons
|Season||Free Range (%)||Captive (%)||P value|
|P value||< 0.01||< 0.01||< 0.01||< 0.05|
a,b,c Means along rows differ significantly (P≤0.05 or 0.01); A, B,C Means along columns differ significantly (P≤0.05 or 0.01)
It was revealed (Table 1) that there was no difference (P≥0.05) among the free-range locations in any season, suggesting that the free-range locations, though geographically different, did not influence infestation rate. It indicated that the elephants, irrespective of geographical locations, were exposed to parasitic infestation in the wilderness. Exposure to parasitic infestation might have arisen from contact with other animals and use of common waterholes. The range of infestation rates (6.25 to 82.86%) in free-range locations as found in the present study, across locations and seasons, falls within the reported figures from different parts of the country. Kashid et al. (2002) reported 25% helminthic infestation incidence in elephants at Kanha National park while, Nishanth et al. (2012) reported endoparasitic infestation of 80%, 88% and 80%, respectively, in free ranging elephants of Tamil Nadu state at Mudumalai sanctuary, Anamalai sanctuary and Sathyamangalam forest. As regards to the comparison between free range and captive locations, it was found that the captive location, as compared to any of the free-range locations, showed a much lower infestation rate in every season, the differences being significant (P≤0.01) in summer and rainy. The lower infestation rates in captive elephants could be ascribed to the stringent bio-security measures followed resulting in the elimination of intermediate hosts affecting transmission of parasites.
In the present study, the range of infestation rates (2.86 to 22.86%) in the captive location across seasons, were found similar to or different from the reported figures. Saseendran et al. (2004) observed an incidence 17.17 percent of helminthic infestation in the captive elephants of Thrissur district in Kerala. Pandit et al. (2015) reported a lower incidence (Fascioloides magna– 9%, Strongyloides westeri– 23%) of parasitic infestation in captive elephants of Nepal. In both the cases, the animals were regularly dewormed with Albendazole @ 2.5 mg/ kg body weight. In contrast, higher infestation rates than in the present study have also been reported. The reported figures were; 41-43 percent for the elephants of Gemini circus (Kashid et al., 2002), 62.5 percent for the temple elephants of Gujarat (Jani, 2008) and 100 percent parasitic infestation in the captive elephants of Nepal (Karki, 2008). The differences in the reported findings might be due to variation in geographical locations, environmental conditions, bio-security measures adopted and deworming practices followed.
Effect of Seasons
As regards to the seasonal influence, it was found that, for each of the free-range locations, the highest rate was in summer followed by rainy and winter. For each of the free-range locations, summer or rainy showed significantly (P ≤ 0.01) higher rates than winter, there being fluctuating trends between summer and rainy. It was found that, while for Chandaka or Similipal, there was no significant (P≥0.05) difference between summer and rainy; for Satkosia, summer showed a significantly (P ≤ 0.01) higher rate than rainy. For the captive location, a similar pattern was observed, in that, the highest rate was recorded in summer followed by rainy and winter. However, while there was no significant (P≥0.05) difference between summer and rainy, the difference between summer and winter was significant (P≤0.05), there being no difference (P≥0.05) between rainy and winter. Thus, it was found that for free-range or captive locations, the highest rate was found in summer followed by rainy and winter.
As regards to the seasonal influence, the highest rate of infestation was recorded in summer followed by rainy and winter, for both free-range and captive locations. The parasite incidence was comparable between summer and rainy seasons for all the study locations. Very low incidence in winter months might be due to the unfavourable environmental temperature and humidity affecting shedding of eggs in faeces. The periodical larval hypobiosis phenomenon is a characteristic of the parasite species belonging to Trichostrongylidae family; therefore, the results of fecal samples examination from autumn-winter season were negative (Gundlach and Sadzikowski, 2004). Increased faecal shedding of the nematode ova during spring time or early summer might be attributed to the ‘spring-rise phenomenon’. The higher prevalence of parasitic infestation during summer could be attributed to the prevalence of conducive climatic conditions (temperature and humidity) for faster rates of hatching of eggs and rapid development to the infective stage as suggested by English (1979). Higher stress in elephants during summer as detected from the faecal cortisol level might be another reason of higher infestation percentage owing to the fact that stress affects host immunity thereby predisposing animals to parasite infestation (Dhabhar and McEwen, 1997; Agarwal and Marshall, 2001). Further, increased susceptibility of individuals to parasites and pathogens due to nutritional stress such as limited food availability and deficiencies in dietary components was reported by Chapman et al. (2006b).
The highest rate of infestation in summer followed by rainy and the lowest in winter, as observed in this study, was similar to the findings of Vanitha et al. (2011), with reports of highest infestation rate during summer (49.0%), followed by monsoon (38.0%), and the lowest infestation rate during winter (7.0%). The findings were further corroborated by those of Pechimuthu (2014), where captive elephants showed a mean higher prevalence during summer (55.0%), followed by monsoon (37.5%), pre-monsoon (25.0%) and post-monsoon (22.5%). Similarly, higher parasitic load during dry season was reported for captive and wild Indian elephants by Watve (1993) and Vidya and Sukumar (2002). In contrast, Mbaya et al. (2013) quoted typically peak helminthic prevalence during the rainy season in African elephants in Nigeria. Unlike the above studies, Baines et al. (2015) observed no strong associations between season (rainy, flood and dry) and the prevalence or density of parasite stages in wild African elephant faeces. The differences in the reports could be due to variation in the climatic conditions of the study locations.
Effect of the Locations
The infestation rates for the free-range locations ranged from 72.50 to 82.86 percent in summer, 60.00 to 62.86 percent in rainy, and 6.25 to 10.71 percent in winter. No significant (P≥0.05) difference was observed among the free-range locations across the seasons. For the captive location of Nandankanan Zoological Park (NZP), the infestation rates were 22.86%, 20.00% and 2.86% in summer, rainy and winter, respectively. The captive location showed a markedly lower infestation rate than any of the free-range locations, in every season. The differences between the captive and any free-range location were found significant (P≤0.01) in summer and rainy, while in winter, no significant (P≥0.05) difference was observed between any of the free range and captive locations.
Spectrum of Endoparasitic Infestation
The spectrum of infestation in different locations and seasons are presented in Table 2. Single as well as mixed endoparasitic infestations were encountered. Single infestations comprised Strongyle spp., Strongyloides spp., Paramphistomum spp., Fasciola spp. and ciliates; while mixed infestations comprised Strongyle spp. + Strongyloides spp., Strongyle spp./Strongyloides spp. + Fasciola spp./ Paramphistomum spp. and Strongyle spp. + Strongyloides spp. + Fasciola spp./ Paramphistomum spp.
Table 2: Spectrum of endoparasitic infestation in different locations and seasons
|Season||Location||Total no. of samples||Single Infestation (%)||Mixed Infestation (%)|
|Positive for endoparasites (%)||Strongyle spp.||Strongyloides spp.||Paramphistomum spp.||Fasciola spp.||Ciliates||Strongyle
|Strongyle spp./ Strongyloides spp. +||Strongyle spp. + Strongyloides spp. + Fasciola spp./ Paramphistomum spp.|
|+ Strongyloides spp.||Fasciola spp./ Paramphistomum spp.|
It was found that location did not influence spectrum of parasites in any season. Season influenced spectrum, winter showing the lowest and rainy the highest. The Strongyle spp. was the only parasite to be observed during winter season, across locations, though Strongyloides spp. and Paramphistomum spp. were found only sporadically. The spectrum of infestation in different locations and seasons are presented in Table 2. It was found that location did not influence spectrum of parasites in any season. In contrast to the present finding, Karki (2008) reported different spectrum and intensity of infestation in location-wise samples of elephants from four different locations namely, Chitwan National Park, Suklaphanta, Bardiya and Koshi Tappu wildlife reserves in Nepal owing to the difference in bio-geographical conditions. Season influenced spectrum of parasites, winter showing the narrowest and rainy the widest. The presence of wider spectrum of endoparasites during summer and rainy might be due to the favorable warm and humid environmental conditions required to complete the life cycle, while the same not being available during winter might be the reason of lower endoparasitic spectrum. Very low incidence in winter months might be due to the unfavourable environmental temperature and humidity affecting shedding of eggs in faeces. The periodical larval hypobiosis is a phenomenon, characteristic of the parasite species belonging to Trichostrongylidae family, therefore the results of fecal samples examination from autumn-winter season were negative (Gundlach and Sadzikowski, 2004). The higher prevalence of parasitic infestation during summer can be attributed to the prevalence of conducive climatic conditions (temperature and humidity) for faster rates of hatching of eggs and rapid development to the infestive stage (English, 1979). The Strongyle spp. was ubiquitous across seasons and locations studied. A similar finding was observed by Vanitha et al. (2011) who reported presence of Strongyle spp. in summer (49%), rainy (41%) and winter (15%) seasons in temple, private and forest department elephants in Tamil Nadu.
The spectrum of parasites observed in the present study (Strongyle spp., Strongyloides spp., Paramphistomum spp., Fasciola spp. and ciliates) was previously reported in the free range and captive elephants. In free range locations, they consisted of Strongyloides spp., Strongyle spp., Bivitellobilharzia spp. and Anoplocephala spp. (Vimalraj et al., 2012; Nishanthet al., 2012; Hinget al., 2013; Vimalraj and Jayathangaraj, 2015; Heinrich, 2016). The same for captive locations comprised Strongyloides spp., Strongyle spp., Fasciola spp., Paramphistomum spp., Fascioloides magna, Balantidium coli and Oesophagostomum spp. (Suresh et al., 2001; Saseendran et al., 2004; Stremme et al., 2007; Jani, 2008; Chandrasekharan et al., 2009; Vanitha et al., 2011; Rahman et al., 2014; Pechimuthu, 2014; Pandit et al., 2015; Heinrich, 2016), while Strongyle spp., Strongyloides spp. and Paramphistomum spp. were reported in semi-captive elephants (Lynsdale et al., 2015). The order of predominance by single or mixed infestations was more or less similar between locations as well as seasons. In free-range or captive locations, and in all seasons, the most predominant species were nematodes (Strongyle spp. and Strongyloides spp.) followed by trematodes (Paramphistomum spp. and Fasciola spp.), which were followed by mixed infestations of different combinations.
The captive location showed a markedly lower endoparasitic infestation rate than any of the free-range locations, in every season. The differences between the captive and any free-range location were found significant (P≤0.01) in summer and rainy, while in winter, no significant (P≥0.05) difference was observed between any of the free range and captive locations. As regards to the seasonal influence, it was found that, for each of the free-range locations, the highest rate was in summer followed by rainy and winter. For each of the free-range locations, summer or rainy showed significantly (P≤0.01) higher rates than winter, there being fluctuating trends between summer and rainy.
Authors are thankful to PCCF (Wildlife) and Chief Wildlife Warden, Odisha for providing scholarship and necessary facilities in the field to conduct the research work. The authors also thank Director, Nandankanan Zoological Park, Bhubaneswar, Odisha for permission to carry out research.