Parasites of two co-occurring house gecko species, Hemidactylus frenatus and Gehyra mutilata from Central Sri Lanka

Two house gecko species, the Asian house gecko, Hemidactylus frenatus (Schlegel, 1836) and the four-clawed gecko, Gehyra mutilate (Wiegmann, 1834) inhabiting urban areas in Kandy and Kegalle districts were examined to determine the types of ecto and endo parasites, their prevalence and intensity of infections. A total of 45 geckos from the two species were dissected after anesthetizing of which 21 individuals (47%) were infected with one or more parasites. Both host species were infected by helminthes such as the nematodes and a fluke species. In addition mites (Geckobia sp.) and an acanthocephalan (Acanthocephalus serendibensis), and ciliates were found only in H. frenatus. Although the two gecko species co-occur, some parasites show host specificity. Nematode infections (possibly Oxyuris infection) were the most common type with 29% prevalence. Although A. serendibensis has been previously described from an agamid, Ceratophora stoddarti, and two geckonids Cnemaspis kandiana and Cnemaspis tropidogaster from Sri Lanka, H. frenatus presents a new host record for A. serendibensis and occurred at high intensity of 510 worms per host. There were no parasites in the blood or body cavity of the geckos examined. More female geckos were infected with parasites than males (χ2=5.20, p<0.05). Although H. frenatus harboured parasites of all five groups while G. mutilate had only two groups, there was no significant difference in the prevalence of infections between the two species (χ2=1.16, p>0.05). None of the identified parasite species have a zoonotic potential.


Introduction
Twenty species of geckos (Family: Gekkonidae) have been recorded in Sri Lanka (de Silva, 2001) and those found in human dwellings are called "house geckos". In this study we aim to identify the parasites found in two house gecko species, the Asian house gecko, Hemidactylus frenatus and the four-clawed gecko, Gehyra mutilate and to determine prevalence and intensity of infections. Hemidactylus frenatushas a worldwide subtropical-tropical distribution and a patchy occurrence outside Asia (Goldberg et al., 1998). International movement of ships and cargo has assisted its spread across the world and populations now exist in numerous islands and countries (Csurhes and Markula, 2009). There is some evidence that H. frenatus can compete and perhaps replace locally native gecko species, especially in urban areas. It is very adaptable and prey on insects and spiders. Gehyra mutilata ranging from India to Myanmar, Indo-China, the Malay Peninsula, and Indonesia to Oceania and coastal Mexico (Goldberg et al., 1998). It is also very adaptable to its surrounding and usually prefers woodlands, rocky areas and human habitats.

Materials & Methods
Geckos inhabiting houses from selected urban sites in Kandy and Kegalle districts in Central Sri Lanka were collected from August 2007 to February 2008. Geckos were identified, euthanized within 12 hr of capture, and necropsies were carried out. Information about sex, microhabitat and the physiological condition of each animal was recorded. External areas of the body such as head region, armpits and anal area and between fingers and toes were examined for ectoparasites. Parasites found were transferred into 70% ethanol and were observed under the dissection microscope and identified.
The body cavity was opened by a longitudinal incision, and the gastrointestinal tract was removed and opened. The esophagus, stomach, small intestine, and large intestine were examined for parasites under a dissecting microscope. Identification was made from these temporary wet mounts. A portion of each part of the gut of each individual was placed on a watch glass and a few drops of saline were added on to it and observed under the light microscope. Live parasites were separated by using a dropper and preserved in 70% ethanol. Permanent slides were prepared by using the single staining procedure (Borax Carmine) for identification. Nematodes were identified after glycerol wet mounts. Smears were prepared from the gut content and were fixed in Shouding's fixative and then double stained in Harris' Heamatoxyline and Eosine and observed under the light microscope for parasites and eggs. The heart was removed and a few drops of blood were taken from a puncture. Blood smears were prepared on a microscope slide and stained with Leishman's dye and observed for blood parasites. The prevalence and the mean intensity of different types of parasites were determined. The difference of prevalence in overall infection was compared between males and females, two sites and two species using a chi

Results
All the geckos dissected looked healthy and active. External appearances of any of the species did not indicate symptoms of any disease. Their microhabitats were mostly inside houses on walls, roofs and other surfaces where there were lights to attract insects. They were also found in outdoors like under logs and surface of the tree barks in the vicinity of the house. Of the 45 individuals examined, 21 (47%) were infected with one or more parasites. The parasitic fauna found in the two species consisted of five broad groups namely one ectoparasitic mite and endo parasites such as nematodes, flukes, acanthocephalans and ciliates (Table 1). There were no parasites in the blood or body cavity of the geckos examined.
Mites were found only in H. frenatus collected from both sites with an overall prevalence 19% (4/21) and an average intensity of five (Table 1). Their body was usually flattened, bright orange to red in color, eyes seemingly absent, four pairs of legs were present except in larvae and body is circular to broadly oval in outline and densely hairy. They were found attached to the skin of hind and forelegs in between fingers and under side of the arms. All the nematodes were found in the small intestine. One species of digenetic trematode was found in the stomach and small intestine of both species which could be Mesocoelium monas. DNA studies are required to confirm the morphological identification of the nematode and trematode species. Larval stage of Acanthocephalus serendibensis and ciliates were found only found in H. frenatus collected from Kandy district. None of the gut associated organs had any parasites. There were no parasites in blood smears or in the body cavity of dissected specimens of both gecko species.
There was no difference in the prevalence of infection between the two sites Kandy and Kegalle (Chi Square test, p>0.05; Table 2) or between the two species (χ 2 =1.16, p>0.05). However, H. frenatus harboured parasites of all five groups while G. mutilate had only nematodes and flukes (Table 2). More female geckos were infected with parasites than males (Chi Square test, p<0.05; Table 2). These two gecko species were infected by generalist helminth species such as the nematodes and the fluke species but Acanthocephala, ciliates and mites were only found in H. frenatus. Geckos are easily spread across the world through ships and cargo and the parasites that they harbor also move with the host species.