A SURVEY TO DETECT PATHOGENS OF REGIONAL IMPORTANCE IN SELECTED NORTHERN QUEENSLAND RODENT SPECIES

1. A SURVEY TO DETECT PATHOGENS OF REGIONAL IMPORTANCE IN SELECTED NORTHERN QUEENSLAND RODENT SPECIES Shovon Chakma1, Jackie Picard1, Richard Duffy2 , Constantin Constantinoiu1 and Bruce Gummow1 1School of Veterinary and Biomedical Sciences, James Cook University, Townsville, Australia 2School of Marine and Tropical Biology, James Cook University, Townsville, Australia House mouse (M. musculus) Black rat (R. rattus) Background Rodents potentially carry several zoonotic pathogens such as Leptospira, Salmonella and Brucella. Since rats and humans live in close proximity, there exists potential for transmission. Studies on the zoonotic diseases carried by rodents in north Queensland were last done in the mid 1970s (Cook et. al., 1966, Glazbrook, 1976, Mesinaet. al., 1974) . This study was carried out to identify zoonotic bacterial and ectoparasitic organisms in rodents from an area as close as possible to the original site where Brucellawas last isolated from native rodents by Cook et al. (1966) and only recently found to be a novel Brucellagenotype (Tiller et al 2010). Methods Seventy one non-native rodents and 38 native rodents were trapped on four properties adjacent to the Woorooroonran National Park, northern Queensland between 9 July 2012 and 14 July 2012 (Fig. 3) (the site of the original Cook et al. work). Ethics approval was only for the euthanasia of non-native rodents. Non-native rodents were euthanased by pentabarbitone sodium injection and preserved in formalin after serum and organs samples were collected. Standard laboratory tests were used to culture bacteria from organs, with a focus on the zoonotic bacteria Salmonella, Brucella and Leptospira (OIE manual, 2012). Ectoparasites and helminths carried by rodents were identified using standard methods (Traub & Dunnet, 1972; Khun & Ludwing, 1966; CDC, 2003; Domrow, 1964). Results and Discussion The percentage of rodents carrying Salmonella (14.29%) was considerably greater than in the previous studies in Queensland (Glazebrook, 1976 and Lee, 1955). All properties surveyed owned livestock and most rodents were trapped near feed sources and could thus potentially transmit the disease to livestock.Leptospirawas not isolated from non-native rodent organs in this study. This finding agreed with the work of Wangdi (2011) that non-native rodents may not be a major source of Leptospira in the Atherton Tableland region. No Brucella organisms were isolated, which was contrary to the 1966 study. This may be because these were not native rodents or because the agent is no longer present. The ectoparasites identified on the black rat (Rattusrattus) were two species of sucking lice, Polyplax spp.  (23.53%) and Hoplopleuraspp. (17.65%), one species of fleas, Stephanocircusharrisoni, one species of mites, Laelaps spp. (41.17%) and one species of hard ticks, Ixodes spp. (17.64%). No ectoparasites were found on the house mouse (Mus musculus). These ectoparasites are known to transmit zoonotic pathogens such as Rickettsia spp. from rat to rat and these could be transmitted to humans  by  other arthropods  that  do  bite  humans. Figure 1: Rodent trapping location N. QLD Figure 2: Trapping sites in Atherton Tablelands Figure 3: Number of rodents trapped by species and by location Conclusions and Recommendations Non-native rodents in Atherton Tablelands carry ectoparasites and bacteria that could have potential public health risks in the area. Non-native rodents have a low prevalence of Brucella and Leptospira on the Atherton Tablelands Further surveillance is required to understand the epidemiology, domestic-wildlife and non-native/native rodent interface of the more important zoonoses for the maintenance of public health. Figure 4: Salmonella choleraesuisssparizonae using API®20E (bioMerieux) Figure 9: S. harrisoni Figure 5: Ixodes spp. Figure 7: Hoplopleura spp. Figure 8: Laelaps spp. Figure 6: Polyplax spp. • References • CDC (CENTERS FOR DISEASE CONTROL & PREVENTION) 2003. Pictorial keys to arthropods, reptiles, birds, and mammals of public health significance, United States, Atlanta, Ga. : Department of Health & Human Services, Centers for Disease Control and Prevention. • COOK, I., CAMPBELL, R. & BARROW, G. 1966. Brucellosis in North Queensland rodents. Australian Veterinary Journal, 42, 5-8. • DOMROW, R. 1965. The genus Laelaps in Australia (Acarina: Laelapidae). 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