Bareng, Barney

Chan, John G.

Shero, Charlene

Young, Laura

English

ScholarSpace at University of Hawai'i at Manoa

Salmonella in Two Gecko Specieson the Island of HawaiiJohn G. ChanCharlene SheroLaura YoungBarney BarengBiology DisciplineUniversity of Hawaii at HiloHilo, Hawaii 96720INTRODUCTIONThe occurrence of Salmonella and other enteric pathogensin reptiles has been reported by Iveson, Mackey and Bamford(l969) and Kourany, Myers and Schneider (1970). Numerousreptilian species were reported as carriers of Salmonella.While r~ptiles were known as carriers of Salmonella theirepidemiological role in human ealmonellosiswas unclearuntil outbreaks from contact with freshwater· turtles wasreported by Williams and Hedson (1965). Kourany and Telford(1981) suggested that gecko lizards might infect man throughbonta~inationof food and eating utensils with their excreta.In Hawaii, geckos are extremely common throughout theislands. Just about every dwelling has its population ofgeckos. While there· are seven gecko species in Hawaii, onlytwo, Hemidactylus frenatus and Lepidodactylus lugubris, arecommon to households. The geckos are insectivoDous and mostoften station themselves along walls and window sills wherethere is sufficient light to attract insects. Although theyare active primarily at night, their presence is revealed bytheir extensive fecal droppings. Since these geckos are oftenfound inside the home in areas where food is prepared orstored, it appears the opportunity for gecko to human trans-mission of salmonellosis might exist. An investigation of asalmonellosis outbreak in Dar es Salaam, Africa by Mackey(1955) indicated household geckos as the source of contamina-tion.In our study, we attempted to establish whether Salmonellabacteria were present in the two species of household geckos,H. frenatus and L. lugubris, and in their droppings.4142MATERIALS AND METHODSCollection and Analysis of Gecko LizardsGeckos are normally active only at night. Hence, collectingwas initiated usually well after dark. The geckos were mostcommon around older buildings especially those with corrugatediron roofing since the space between the roof covering andwalls offered numerous crevices in which thegeckos could hide.The geckos were most numerous around light fixtures andwindow areas. These well-lit areas served as establishedfeeding sites and were heavily marked by gecko excreta.Once the feeding sites were located the geckos were spottedwith flashlights and captured by knocking them off the wallwith heavy rubber bands. The rubber band was stretched overthe index finger and simply aimed at the gecko. With a bit ofpractice, a surprising degree of accuracy was attained. Whenhit, the stunned gecko would falloff the wall and couldeasily be captured. Later, a water spray was found to beequally effective. The spray loosened thegeckos' grip causingthem to falloff the wall; this method had the added advantagein that the animals were recovered undamaged.The captured animals were placed in individual plasticpouches and taken back to the laboratory in a styrofoam chest.Upon arrival at the laboratory, the pouches with the geckoswere refrigerated overnight at 4C. By next morning the geckostreated in this fashion were in a state of stupor. Beforeinitiating dissection, each gecko was killed by severing thespinal cord just behind the neck. With the animal pinned onits back, the abdomen was swabbed with 70 percent alcohol,then an incision was made to expose the interna} organs. Ahemostat was clamped onto the esophagus just anterior to thestomach, while the lower intestine was clamped near the analopening. The entire gut was then severed and removed. Thegut contents were then squeezed out, and transferred, alongwith the minced gut, to 10 ml of Tetrathionate Broth withBrilliant Green dye and iodine. After incubation for 24 hoursat 37C a loopful of the enrichment broth was streaked ontoBrilliant Green Agar (BGA) , MacConkey Agar and SS Agar ~ndincubated for 24 hours at 37C. Suspected salmonella~likecolonies were restreaked onto BGA for further testing. Con-firmation of Salmonella was made by testing cultures onTriple Sugar Iron and using a diagnostic test system, eitherRoche Enterotube II or General Diagnostic's MICRO-ID system.Final confirmation was made with Salmonella Polyvalent 0 andVi antisera (Difco). In some cases suspected colonies weretested directly with the antisera for rapid confirmation.43Collection and Analysis of Gecko Droppings. . Fecal droppings were collected from a variety of habitats.Collections were made without regard to the condition or age ofthe droppings. Individual droppings were picked off surfaceswith a sterile cotton-tipped swab and transferred to an enrich-ment tube containing 10 ml tetrathionate broth and macerated.Subsequent analysis for Salmonella was conducted in the samemanner described for the gecko gut.All isolated identified as Salmonella await further testing.to determine the specific serotype.Sampling SitesGeckos were collected from 13 sites and droppings were col-lected from 17 sites on the Island of Hawaii. The samplingsit~s encompassed a variety of structures ranging from classroombuildings, restaurants, dwellings and coconut trees. An attempt.was made to cover as wide a geographical range as possible. Mostsampling locations were at altitudes ranging from sea level toabout 500 feet. Higher elevations had far fewer geckos.Results and DiscussionOur results show Salmonella-infected geckos to be distributedthroughout the island 'of Hawaii~ Of 13 sites surveyed, 10 yieldedgeckos with Salmonella - a 76.9 percent occurrence (Table 1). Theonly sites not yielding Salmonella were Hapuna Beach Park on theleeward side of the island and Mooheau Park in Hilo. Hilo ShoppingCenter yielded only a single gecko which tested negative. HapunaBeach and Mooheau Park differed from other collecting sites inbeing located close to the seashore in areas of low permanent humanpopulation. Helm (1981) in his study of 7 urban subdivisions onOahu found Salmonella-infected geckos at all of the sampling sites.It may be that the incidence of Salmonella in geckos is correlatedwith human population density or activities. However, Kournay andTelford (1981) found Salmonella-infected reptiles in remote unin-habited forest areas as well as in urban areas in Panama; theysuggest that reptile-salmonellae associations may be independentof human activities.44The incidence of Salmonella-infected geckos varied fromsite to,site on the island of Hawaii. The incidences rangedfrom 0 to 22.2 percent occurrence. The highest levels of positiveSalmonella isolations were made from geckos at Kawaihae Harbor,Hawaii Community College and Pepeekeo. Kourany and Telford (1981)found the highest level of reptile infection to be attributed togreater contact with sources of infection such as animal and humanexcreta. In Hawaii the infection of geckos by Salmonella conta-minated animal excreta is unlikely. However, insects such ascockroaches are well known as carriers for Salmonella (Bi·tter andWilliams, 1949). The ingestion of cockroaches may account forthe rela·tively high Salmonella incidence in some of the geckosamples. In a sample of 10 geckos captured at the Universityof Hawaii at Hilo campus, 4 had cockroaches in their stomachs.The overall incidence of Salmonella on the Island of Hawaiiwas 18 of 151 specimens - 11.9 percent. Our findings indicatethat Salmonella is widespread among the geckos of the Island ofHawaii. Helm (198l) showed even higher incidence of Salmonellain the geckos of Oahu. Of 70 geckos captured on Oahu, 32 werepositive for Salmonella, a 45.7 percent incidence. The higherincidence of positive geckos on Oahu might be due to a greateropportunity to contact Salmonella sources.In Panama, Salmonella was isolated from 131 of 447 (29.4percent) reptiles examined by Kourany and Telford (1981). Theresults of our study and others suggest salmonellae-reptileassociation to be commonplace.If reptiles are to serve as sources of human salmonellosis,infection via their excreta would be the most likely mode oftransmission. Our examination of gecko droppings, however,showed only 4 of 224 (1.8 percent) droppings from 17 sites tobe positive for S.almonella (Table 2). The incidence of droppingspositive for Salmonella seems low when compared to the percentageof geckos infected. Helm (1981) found 7 of 23 (30.4 percent)gecko feces positive for Salmonella in 9 households on Oahu.These homes also had 27 of 63 geckos (42.9 percent) positive forSalmonella.It.appears that gecko lizards in Hawaii present a vastreserV01r of Salmonella. Transmission of Salmonella to humansfrom geckos would most likely occur through contamination offoods and water by their feces. A comparison of data from theislands of Oahu and Hawaii show a higher incidence of Salmonella-infe~t7d geckos.in highly urbanized Oahu. It may be that highdens1t1es of an1mals, humans, insects and geckos promote the in-terspecies transmission of Salmonella.How geckos acquired their Salmonella microflora needs to bedetermined. It is suspected that insects--in particular, cock-roaches--to be the major source of Salmonella for geckos ..........__._--45ACKNOWLEDGEMENTThe authors wish to thank R. Jake Marley for assistan6eincapturing geckos and to the National Institute of Health forsupport through the Minority Biomedical Research Support Grant2S06.RR 08073-10AlLITERATURE CITEDBitter, R. S. and o. B. Williams, 1949. Enteric Organisms fromthe American Cockroach. J. Infect. Dis. 85(1) :87-90Helm, F. L. 1981. The role of geckos in the transmission ofSalmonella in Hawaii with emphasis on Salmonella weltevreden,Master Thesis. School of Public Health, University of Hawaii,47 p.Iveson, J. B., E. M. Mackey and B. Bamford. 1969. Salmonellaand Arizona in reptiles and man in western Australia, J.Hygiene, 67:135-141.Kourany, M., C. W. Meyers and C. R. Schneider, 1970.amphibians and reptiles as carriers of Salmonella.Med. Hygiene. 19:632-638.PanamanianAm. J. Trop.Kourany, M. and S. Telford. 1981. Lizards in the ecology ofsalmonellosis in Panama. Appl. Environ. Microbiol. 41(5):1248-1253.Mackey, J. P.Afr. Med. J.1955. Salmonellosis in Dar es Salaam.32:1-6.East.Williams, L. P. and H. L. Hedson, 1965.of salmonellosis. J. Am. Med. Assoc.Pet turtles as a cause192:347.46TABLE 1. Salmonella in Geckos from VariousSites on the Island of HawaiiNumber of Salmonella PositiveSampling Sites. Geckos Number PercentUH Hilo 1 28 3 10.7Mooheau Park 7 0 0Cafe II A" 8 1 12.5Hilo Shopping Center 1 0 0Hawaii Community College 9 2 22.2Keaau 2 17 2 11.8Captain Cook 6 1 16.6Honaunau 22 2 9.1Hapuna Beach 10 0 0Kawaihae 15 3 20.0Kailua 14 2 14.3Pepeekeo 5 1 20.0Pahoa 9 1 11.1151 18 11. 91Wentworth Hall and College Hall2Keaau Police Station and Credit Union BuildingTABLE 2. Salmonella Isolations from GeckoFeces, Island of Hawaii47Number ofNo. of Fecal Positive for SalmonellaSampling Area Sites Droppings Number PercentHi10 District 9 141 2 1.4Hamakua District 2 14 0 0Ka'u District 1 10 0 0Kailua, Kona District 5 59 2 3.417 224 4 4.8

Salmonella in two gecko species on the island of Hawaii

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Salmonella in two gecko species on the island of Hawaii

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