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European Journal of WildlifeResearch ISSN 1612-4642 Eur J Wildl ResDOI 10.1007/s10344-015-0949-x

Galoncus perniciosus-associated death in awild Bengal tiger (Panthera tigris)

N. Kalaivanan, C. Sreekumar,R. Venkataramanan, P. Selvan, R. AnilKumar, Arun Zacharia & M. Iyue

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SHORT COMMUNICATION

Galoncus perniciosus-associated death in a wild Bengal tiger(Panthera tigris)

N. Kalaivanan2& C. Sreekumar3 & R. Venkataramanan3

& P. Selvan1& R. Anil Kumar1 &

Arun Zacharia4 & M. Iyue1

Received: 13 April 2015 /Revised: 16 July 2015 /Accepted: 17 July 2015# Springer-Verlag Berlin Heidelberg 2015

Abstract The tiger (Panthera tigris), which is the largest liv-ing feline, is waging a grim battle for survival, with only lessthan 2300 left out in the wild. Information on the cause ofdeath of every single tiger is important, as it will help in de-vising suitable conservation measures. However, most of thedeaths reported in the wild are due to ‘unknown etiology’ andreports on infectious causes are almost absent. The presentpaper describes the death of a wild tiger, associated with in-fection of the submucosal hookworm of large felines,Galoncus perniciosus. Necropsy revealed that the small intes-tinal serosa was congested with extensive paint-brushhaemorrhages for the most part. There were about 27 intestinalnodules, each measuring about 1.5 cm in diameter, containinghaemorrhagic exudate and parasites identified asG. perniciosus. The serosa also showed clear ante-mortemcircumferential tears in seven places; some of them were su-perficial, limited to the serosa, while others extended into themuscularis mucosa. The possibility of death due tosepticaemia or neurogenic shock resulting from galoncosis is

discussed based on the circumstances and distinct necropsylesions. The implications of such infectious diseases on thetiger conservation strategy are also discussed.

Keywords Tiger . Panthera tigris . Hookworm .Galoncusperniciosus . Intestinal nodules . Septicaemia

Tiger (Panthera tigris), the largest living feline on earth, holds asignificant position in the upper most trophic level of the eco-logical pyramid in the wild/forest and is grouped in schedule Iof the Wildlife Protection Act of India. However, the species iswaging a grim battle for survival (Chundawat et al. 2008), withhabitat loss and demand for body parts taking a heavy toll onthe dwindling population. Presently, there are fewer than 2300of these magnificent beasts alive in the wild in India. It is im-portant to analyse every single event of death, not only to un-derstand the cause but also to rule out other conflict relatedreasons such as poisonings. Unnatural deaths caused by poison-ing, both primary (Venkataramanan et al. 2008) and secondary(Kalaivanan et al. 2011), as well as poaching, make up for themost common causes of deaths in wild carnivores. Some of thecommon aetiology for natural death in wild tigers are old age,territorial (intraspecific) fights, injuries caused during hunting(interspecies fight), and disease (Tigernet report 2014). Infec-tious disease, as a cause of death in wild tigers, is uncommon,and a confirmative diagnosis in such cases is even rarer.Galoncus perniciosus, a hookworm of large felines, has beenattributed to the death of tigers in captivity (Alexander et al.2011). Natural selection operating in the wild maintains anoptimal population density. In the evolutionary process, para-sites are known to co-exist with the hosts, especially in the wild.There are no documented reports incriminating G. perniciosuswith death of tigers in the wild. The present paper describes

In memory of late Shri. A.C. Soundarrajan, wildlife enthusiast andmember of Nilgiri Wildlife and Environment Association, whodedicated his life for the welfare of the Nilgiri Biosphere Reserve. Theforests have lost a good friend!

* C. Sreekumarsreesnake@gmail.com

1 Sheep Breeding Research Station, Tamil Nadu Veterinary andAnimal Sciences University, Sandynallah, The Nilgiris, TamilNadu 643 237, India

2 Forest Veterinary Dispensary, Mudumalai, Tamil Nadu, India3 Present address: Postgraduate Research Institute in Animal Sciences,

Kattupakkam, Kancheepuram, Tamil Nadu 603 203, India4 Wildlife Disease Diagnostic Laboratory, Wayanad, Kerala, India

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death of a wild tiger associated withG. perniciosus infection, inthe Nilgiri Biosphere Reserve.

Materials and methods

It was reported that the carcass of a tiger was found near astream in Morakutty reserve land near Pikkapatthy Toda tribalmund (village) of the Udhagai North Range, Nilgiri NorthForest Division, Tamil Nadu. The site was thoroughly exam-ined, and preliminary investigation with the members of theToda tribe, regarding the movement of tigers in the region,was carried out. Necropsy was conducted at the same site.The salient lesions were noted, and clinical samples were col-lected for examination. Helminths extracted from the nodulesof the intestine were fixed in 10 % formalin along with repre-sentative samples from all the visceral organs, for histopatho-logical examination. The helminths were processed by stan-dard technique for species identification (Yamaguti 1953).

Results

The carcass was that of a healthy adult male tiger of about8 years and was found with its hind quarters and abdomensubmerged in water of the stream and the anterior portion onthe banks. The soft grass just above the site showed indica-tions that the animal had rested there for a long time and evenrolled around. Investigation with members of the Toda tribeliving nearby revealed that the animal had been sighted in theregion for the past fewweeks. They also reported that they hadheard prolonged vocalization from the animal about 3 daysback.

The carcass was putrefied, with maggots, the largest mea-suring about 1.5 cm long, found all over. Most of the internalorgans showed signs of autolysis. The subcutaneous, mesen-teric, epicardial, and perirenal fat depots of the animal were inexcellent condition. The liver, spleen, and kidney showed pu-trefactive changes. The epicardium of the heart was congestedand slightly injected. The chambers of the heart were filledwith clotted blood. No abnormalities were detected in themajor vessels. The stomach did not have any solid ingestaand contained only about one and half litres of water. Thesmall intestinal serosa was congested with extensive paint-brush haemorrhages for the most part (Fig. 1a). There wereabout 27 circular nodules, each measuring about 1.5 cm indiameter, visible from the serosal surface of the small intes-tines (Fig. 1a). The serosa also showed clear ante-mortemcircumferential tears in seven places. Some of the tears weresuperficial, limited to the serosa (Fig. 1a), while others extend-ed into themuscularis mucosa (Fig. 1b). The mucosal surface,in the region of the nodules, was slightly congested andoedematous. The nodules projected into the intestinal lumen

with a central orifice (Fig. 1c). The contents of the noduleswere haemorrhagic and, on pressure, extruded nematodes(Fig. 1c). Cut section of the nodule revealed mononuclearinfiltration of the nodular parenchyma, with the presence ofsections of nematodes associated with plugs of mucosa(Fig. 1d). The entire intestinal tract was also practically empty,barring scanty, semisolid contents and a few pellets of formedfaeces in the rectum.

The worms collected from the nodules were stout and, onmicroscopic examination, were indistinguishable from thesubmucosal ancylostome G. perniciosus, as described byYamaguti (1953). The anterior end revealed the presence ofa well-developed, chitinous buccal capsule with two dorsalteeth (Fig. 2a). The cuticle had fine striations. Females were17 mm long and had a distinct digitiform tail with a fine,terminal cuticular appendage (Fig. 2b). The males were11 mm long with slender, long, sub-equal (~1750–1800 μm)spicules and a gubernaculum (60 μm), shaped like a ‘tadpole’(Fig. 2c, d). They also had a well-developed bursa containinglateral lobes supported by three bursal rays and a dorsal rayforked at the tip (Fig. 2d).

Discussion

The tiger conservation efforts taken up by India through ‘Pro-ject Tiger’ and supported bymany other countries are in a waya flagship programme that would determine if and how aturnaround can be brought from the steady erosion of forestareas. Considering the very small numbers of tigers present inthe wild, the slogan of ‘every tiger counts’ is indeed fitting.The success of Project Tiger, in essence, depends upon pro-viding this specialist animal adequate forest cover andpreventing conflict-induced death to the extent possible. Toachieve this, it is pertinent that all cases of tiger mortality arethoroughly investigated and specific aetiology determined.

However, in reality, the situation is far from satisfactory.Details on death of tigers, as revealed by the official website ofNational Tiger Conservation Authority of India (Tigernet re-port 2014), indicate that the cause(s) of death for more thanhalf (137) of the 257 recorded tiger deaths reported in Indiasince 2010 to 2014 is not known. About one fourth of thedeaths (59 out of 237) have been attributed to natural causes,among which old age and territorial fights appear to be mostcommon. However, no information is available on any specif-ic causes of death, like those due to infectious diseases.

The tiger in the present case was, based on its body con-formation, dentition, and fat depots, a very healthy male in thepeak of its life. The time of death was about 72 h prior tonecropsy, going by the development of maggots and the wetand cold weather conditions prevailing in that region. Theanimal had excellent fat depots indicating that the cause ofdeath was acute. The place where the carcass was found was

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the core jungle, away from human habitation (except for aToda tribal settlement), ruling out conflict with humans asthe reason of death. Retaliatory and secondary poisoning werealso discounted as reasons, as the stomach was practicallyempty, barring the presence of water the animal had probablydrunk before its death. These circumstances, and the presenceof distinct necropsy lesions, pointed to the possibility of anacute infectious disease being the aetiology.

The submucosal hookworm of large felids, G. perniciosus,has been associated with the deaths of wild felids in captivity.Kono (1952) reported a case of ‘ancylostomiasis’ (due toG. perniciosus) in a leopard imported from Siam to Kagoshi-ma zoo. Patnaik et al. (1971) identified G. perniciosus in theintestines of captive lions. Niphadkar et al. (1989) identifiedGaloncus rammohanii from a leopard in India. Death of whitetigers in Ragunan zoo, South Jakarta, has been attributed toG. perniciosus (Report 2001). Shirbhate (2006) reviewed theoccurrence ofG. perniciosus among leopards in zoos in India.Alexander et al. (2011) foundG. perniciosus lesions in an oldcaptive tiger that died in a zoo. In the wild, Pythal et al.(1993) found G. perniciosus and Paragonimus westermaniinfections in a carcass of a wild leopard. However, there

are no confirmed reports of G. perniciosus causing death inwild tigers.

The lesions found in the tiger were essentially limited to thesmall intestines. Extensive, serosal paint-brush haemorrhageswere found, especially in the regions of the intestines whichhad numerous nodules. It is possible that the serosal tears werecaused by asynchronous, violent peristalsis resulting from theneuromuscular deformities induced by the nodules. Normalperistalsis is a synchronous action that requires neuromuscularcoordination between the nerves and smooth muscles liningthe intestines. Denervation of intestine has been shown tocause altered and significant increase in colonic motility(Lee et al. 2008). The damage caused to both the musclesand the nerves by the presence of large number of nodulescould have led to increased, powerful asynchronous peristal-sis, resulting in severe colicky pain and serosal tear. The pres-ence of distinct ‘rings of constriction’, mainly in the regions ofthe nodules (Fig. 1a), supports this view. Further, there wereno obstructive intestinal lesions (like intussusception or vol-vulus) or ascites, indicating that the episode was acute. Thefact that the animal had tried to alleviate its pain by trying toimmerse its trunk in the stream, that vocalization was heard by

Fig. 1 Salient lesions found in the tiger carcass. a Congestion andextensive ‘paint-brush’ haemorrhages all over the small intestinalserosa, along with the presence of groups of nodules (white arrow),visible from the serosal side. A partial circumferential tear of the serosacan also be seen (black arrow). Arrowheads point to a ‘ring ofconstriction’ along the circumference of the intestine adjacent to anodule. Note the rich fat depots along the mesentery. b Extensiveserosal ‘paint-brush’ haemorrhage with the presence of a deep tear

extending to the muscularis mucosa of the intestine. Note the presenceof maggots. c Luminal surface of the intestine showing the presence of anodule with a central opening. Note mild, generalized congestion of theintestinal mucosa and extrusion of nematode and serosanguinous exudatefrom the nodule on pressure. d Section of a nodule revealing the presenceof transverse section of nematode in association with a mucosal plug.Generalized mononuclear infiltration can be noticed in the parenchyma(haematoxylin and eosin ×200)

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the villagers, and that it had apparently rolled in the grass (inpain) provides oblique evidence to this assumption. Consider-ing the severity of the condition, it is possible that the animalcould have died due to neurogenic shock resulting from theextreme pain.

Verminous nodules in the intestines can also act as a pointof entry for pathogenic microbes into the system. Septicaemiaresulting from such bacterial invasion can lead to death.Septicaemia due to Bacillus coli (Escherichia coli) and faecalStreptococci, originating from the damaged mucosa in theregions ofGaloncus nodules in the intestine of a captive leop-ard, has already been reported (Perry 1921). The bacteria wereisolated from the heart blood, mesenteric lymph node, andspleen of the leopard, which had died in a zoo. Kono (1952)also found lesions similar to oesophagostomosis in the intes-tines of the leopard. In the case of the tiger here, it is entirelypossible that the haemorrhages seen in the intestinal serosawere in response to the septicaemia. However, bacterial isola-tion and culture could not be attempted as the carcass wasputrefied.

The identity of the nematode was confirmed asG. perniciosus, based on the morphology of the male andfemale specimens obtained from the nodule. The life cycleof G. perniciosus is not fully known. Perry (1921) reportedthe presence of larval stages in the nodules from the intestinesof the leopard. However, there have been no subsequent re-ports of the same. In the present case, no larval stages were

found in the nodules. It is likely that the parasite is ageohelminth like other hookworms, with percutaneous infec-tion being the preferred mode of entry into final host (Khalail1922). Instances of galoncosis among large felines (whichwere presumably captive bred and maintained extensively incaptivity) in zoos also point to this mode of infection. How-ever, considering that tigers are solitary animals with a verywide geographical range, it would be intriguing to understandthe mechanism by which the life cycle is completed. It is quitepossible that the parasites utilize transport hosts, includingmany of the prey species, to improve their chances of reachingthe final host. Unlike in captivity, in the wild, it is presumedthat parasites tend to co-exist in balance with their hosts andextraneous circumstances are needed to tilt this balance infavour of parasites, leading to overt disease. So far,Galoncus-related deaths have been reported only in captivetigers. The present case of clinical galoncosis, leading todeath, in wild tigers points to a wider role of the parasite. Tounderstand the role of parasites and impact of any infectiousdisease, long-term monitoring of population, habitat quality,and pathogens, along with the extent of anthropogenic inter-vention and biotic pressure, is important. Conduction of de-tailed necropsy to ascertain the causes of death in every deathof wild tigers is warranted. As the number of tigers in the wildis already perilously low, each of such incidences needs to beanalysed thoroughly. Control of any infectious disease in thewild would pose tremendous logistical problems. However,

Fig. 2 Distinguishingmorphological features ofGaloncus perniciosus include thefollowing: a a typicalancylostomatid buccal capsule,armed with two chitinous teeth atthe anterior end. b The femaletail-end showing the slenderdigitiform process with a thin,cuticular appendage (arrow).Note the fine cuticular striationson the body. c A pair of long,slender, sub-equal spicules withthe presence of a copulatory bursaof the male. d Male copulatorybursa showing three bursal rayseach (1, 2, and 3) on the laterallobes along with a dorsal rayforked at the tip (arrow). A ‘tad-pole’-shaped gubernaculum canbe seen (arrowhead)

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considering the importance of conservation of these animals,efforts should be undertaken to elucidate the life cycle of path-ogens like G. perniciosus to design effective controlstrategies.

Acknowledgments The authors thank the Professor and Head, Depart-ment of Veterinary Parasitology, Madras Veterinary College, for facilitat-ing the identification of the parasite

Conflict of interest The authors declare that they have no competinginterests.

Compliance with ethical standards This article does not contain anystudies with human participants or animals performed by any of theauthors.

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