Phylogenetic relationship and variation of alarm call traits of populations of red‐cheeked ground squirrels (Spermophilus erythrogenys sensu lato) suggest taxonomic delineation

Distribution area and taxonomic borders within the species complex Spermophilus erythrogenys sensu lato remain questionable. Early evidence suggests that red‐cheeked ground squirrels of Southeast Kazakhstan are remarkably different in terms of the acoustic structure of their alarm calls from the red‐cheeked ground squirrels of the Kurgan region in Russia. In this study, we analyzed the differences in the acoustic structure of the alarm call and mitochondrial DNA (complete control region, 1005–1006 bp and complete cytochrome b gene, 1140 bp) in 3 populations of red‐cheeked ground squirrels (Tara, Altyn‐Emel and Balkhash), all located within areas isolated by geographical barriers in Southeast Kazakhstan. We found that the alarm call variables were similar between the 3 study populations and differed by the maximum fundamental frequency (8.46 ± 0.75 kHz) from the values (5.62 ± 0.06 kHz) reported for the red‐cheeked ground squirrels from the Kurgan region of Russia. Variation in mtDNA control region was only 3% and variation in cytochrome b gene was only 2.5%. Phylogenetic trees based on cytochrome b gene polymorphism of 44 individuals from the study area and adjacent territories indicated 3 clades with high (98–100%) bootstrap support: “intermedius,” “brevicauda” and “iliensis”). We conclude that the 3 study populations in Southeast Kazakhstan belong to the clade intermedius and suggest a taxonomical revision of the species complex Spermophilus erythrogenys sensu lato, including analyses of nuclear DNA and alarm calls for populations of the brevicauda and iliensis clades.     

Simulation model for Campylobacter cross-contamination during poultry processing at slaughterhouses

Broiler meat is regarded as the most common source of Campylobacter infection and risk management measures are required to reduce broiler meat contamination. Among the quantitative risk assessments for Campylobacter in broiler meat, evaluation of the poultry processing stage is particularly important for predicting the contamination level of broiler meat and the effects of control measures. In this study, we built a simulation model for cross‐contamination during poultry processing focusing on Campylobacter contamination at the individual carcass level. Using this model, we examined changes in the prevalence of contaminated carcasses and the number of Campylobacter per carcass after processing. As a result, it was found that the prevalence and number of Campylobacter after processing were largely influenced by the number of Campylobacter on the contaminated carcasses before processing. In the baseline model, where it was assumed that the mean number of Campylobacter on contaminated carcasses before processing was 4.7 log₁₀ cfu per carcass, the prevalence after processing was less than that before processing. Although the median value of Campylobacter on contaminated carcasses was reduced after processing, the distributions after processing became wider and the upper limit of the 95% credible interval of Campylobacter on contaminated carcasses remained elevated. The individual‐based simulation model can trace individual level changes considering discrete interactions, while models tracing mean values cannot handle these interactions in detail. The individual‐based approach is considered useful for modelling cross‐contamination among individual carcasses during poultry processing.     

Occurrences of thermophilic <Emphasis Type="Italic">Campylobacter</Emphasis> in cattle slaughtered at Morogoro municipal abattoir,Tanzania

An investigation was conducted in Morogoro municipality to assess the likelihood of slaughter cattle posing public health risk of contaminating carcasses with thermophilic Campylobacter. Butchers and meat shopkeepers were interviewed on source of slaughter cattle, method of animal and carcass transportation, carcass dressing, meat storage facilities, access to clean water and availability of food hygiene practices. Faecal samples were collected from 107 slaughter cattle and after slaughter; four different parts of dressed carcasses (i.e. from ham, neck, pelvis and thigh muscles) were also sampled. In addition 107 cattle meat samples for Campylobacter culture were collected in different meat shops. The samples were subjected to standard bacteriological examination using Skirrows protocol. It was found that cattle slaughter, dressing and meat handling in meatshops was done under unhygienic condition. Thermophilic Campylobacter prevalence in slaughter cattle was 5.6% while contamination rate of dressed carcasses and cattle meat at shops was 9.3% and 1.9%, respectively. The majority of thermophilic Campylobacter isolated were C. jejuni (88.9%) while C. coli was isolated at 11.1%. Findings of this study suggest possibility of humans acquiring zoonotic Campylobacter infections from cattle meat particularly when meat preparation and processing is not done properly. More work is required to establish the magnitude of zoonotic enteric Campylobacteriosis in humans and epidemiological role of cattle and other animals in the study area.     

Interrelationship of soil moisture and temperature to sylvatic plague cycle among prairie dogs in the Western United States

Plague, caused by Yersinia pestis, is a flea-borne disease that is endemic in areas throughout the world due to its successful maintenance in a sylvatic cycle, mainly in areas with temperate climates. Burrowing rodents are thought to play a key role in the enzootic maintenance as well as epizootic outbreaks of plague. In the United States, prairie dogs (Cynomys), rodents (Muridae), and ground squirrels (Spermophilus) are susceptible to infection and are parasitized by fleas that transmit plague. In particular, prairie dogs can experience outbreaks that rapidly spread, which can lead to extirpation of colonies. A number of ecological parameters, including climate, are associated with these epizootics. In this study, we asked whether soil parameters, primarily moisture and temperature, are associated with outbreaks of plague in black-tailed prairie dogs and Gunnison's prairie dogs in the Western United States, and at what depth these associations were apparent. We collected publicly available county-level information on the occurrence of population declines or colony extirpation, while historical soil data was collected from SCAN and USCRN stations in counties and states where prairie dogs have been located. The analysis suggests that soil moisture at lower depths correlates with colony die-offs, in addition to temperature near the surface, with key differences within the landscape ecology that impact the occurrence of plague. Overall, the model suggests that the burrow environment may play a significant role in the epizootic spread of disease amongst black-tailed and Gunnison's prairie dogs.     

Longevity of Mycobacterium bovis in brushtail possum (Trichosurus vulpecula) carcasses,and contact rates between possums and carcasses

Abstract

AIM: To determine, for a variety of environmental conditions, how long Mycobacterium bovis might remain viable inside the carcass of a brushtail possum (Trichosurus vulpecula) that died of bovine tuberculosis (Tb), and to measure the rate of contact between free-ranging possums and possum carcasses.

METHODS: Lesions of M. bovis were simulated by inoculating excised spleens weighing 0.5–1 g with 0.2 mL liquid culture containing approximately 5 x 10⁷ cfu M. bovis/mL. Simulated lesions were inserted into possum carcasses (n=48) at the peripheral lymph nodes. Carcasses were placed in the field at two sites (a tussock grassland and a podocarp-broadleaved forest site) and in two seasons (summer and winter) for up to 62 days. Survival rates of M. bovis were estimated by sampling the simulated lesions over time, and culturing the recovered lesion to determine if any viable M. bovis bacteria were present.

The time taken for a free-ranging possum to first encounter a dead possum in its home range was estimated by live-trapping possums and fitting them with proximity loggers (n=13). A ‘contact’ was recorded if these possums came within 40–50 cm of proximity loggers fitted to possum carcasses.

RESULTS: There were strong seasonal and site effects in the survival rate of M. bovis in possum carcasses. In the grassland habitat, no viable bacilli were cultured from any carcass after 3 days in summer, whereas in winter all samples were culture-positive for the first 20 days, and some were still positive after 27 days. The survival rates for forest habitat were intermediate between the results for grassland, and there were no culture-positive carcasses after 9 days in summer or 27 days in winter.

In summer, infected carcasses (n=6) were first encountered by possums a mean 1.9 (range 0.4–6.7) days after placement.

CONCLUSIONS: Possum carcasses were contacted by free-ranging possums within the period that viable M. bovis were shown to survive in a carcass. The risk of such infection is likely to be most significant in winter or in areas with microhabitats where the survival of M. bovis is high. However, the generally low survival rate of M. bovis in possum carcasses and the low frequency of possum-to-carcass contacts indicate this route of transmission alone could not maintain Tb in a possum population.     

Prevalence of the Bacterium Coxiella burnetii in Wild Rodents from a Canadian Natural Environment Park

Zoonotic diseases impact both wild and domestic animal populations and can be transmitted to humans through close contact with animal species. Reservoir species acting as vectors are major traffickers of disease. Rodents contribute to the transmission of Coxiella burnetii although little is known about its prevalence in wild animal populations. DNA was extracted from genital swabs collected from woodland jumping mice, deer mice, Southern red‐backed voles, Eastern chipmunks, North American red squirrels, as well as Southern and Northern flying squirrels collected from Algonquin Park, Canada. The presence of C. burnetii was determined through real‐time PCR. All species sampled had some prevalence of infection, except Eastern chipmunks, indicating wild rodents in Algonquin Park are reservoirs for C. burnetii. Emerging zoonotic diseases are linked to increasing globalization. Contact amongst individuals increases as crowding, habitat loss and fragmentation increase within wild spaces. Parks often act as a last refuge for wildlife but may also be an important transmission zone of wildlife disease to humans. Investigations that attempt to discover wild reservoir species of zoonotic disease are critically important to understanding the risk of pathogen exchange between wild and human populations.     

The bacteriological condition of eviscerated chickens processed under controlled conditions in a spin-chilling system and sampled by two different methods

Quantitative changes have been determined in the flora of chicken carcasses after passage through a series of three separate spin‐chillers. The majority of organisms were eliminated from the chill‐water during processing by using 1.7 1 of water per carcass and 45 to 50 ppm of total residual chlorine in the first two chillers and 1.0 1 of water per carcass and 25 to 30 ppm of residual chlorine in the third chiller.

Total viable counts at 20 and 37 °C and levels of coli‐aerogenes bacteria obtained from the rinsing of whole carcasses were reduced by more than 90% during chilling. Results obtained both with and without the use of chlorination compared favourably with those claimed for other chilling systems. It was concluded that the main effect of chlorination in the chillers was to destroy organisms washed from the carcasses, thus avoiding recontamination.

A comparison of two different sampling methods showed that maceration of neck‐skin usually gave higher counts of both faecal and spoilage bacteria after chilling than the rinsing of whole carcasses.     

A scrape‐sampling device for the microbiological examination of poultry carcasses

1. A device was developed to permit standardisation of the scrape‐sampling method and facilitate sampling of different parts of the poultry‐carcass.

2. Scrape‐sampling of turkey carcasses from five different stages in processing yielded only slightly lower counts of micro‐organisms than maceration of excised skin samples in the Colworth Stomacher, thus indicating that the scrape method removed a large proportion of the organisms present on the skin. Only at two stages of processing were the differences in count significant (P<0.05).     

Factors associated with endemic raccoon (Procyon lotor) rabies in terrestrial mammals in New York State, USA

This study evaluated characteristics associated with raccoon (Procyon lotor) rabies in New York State (NYS), USA, where this disease has been endemic for the last 15 years. The study included 4448 cases of raccoon rabies in terrestrial mammals reported across 1639 census tracts of NYS during 1997-2003. A Poisson-regression model with census tract-year as the unit of analysis revealed a higher number of raccoon-variant rabies cases per square kilometer in census tracts with each percent increase in the proportion of low-intensity residential areas (those with a lower concentration of housing units) (RR=7.68) and a lack of rivers/lakes (RR=1.20) and major roads (RR=1.10), while the number of cases decreased with each 1-m increase in land elevation (RR=0.998), and each percent increase in the proportion of wetlands (RR=0.01). The model was adjusted for county, ecoregion, and latitude to help control for unknown spatially dependent covariates. The model may be used in prioritizing areas for rabies control based on differential risk, including use of costly intervention methods such as oral rabies vaccine.     

Surveys of rodent‐borne disease in Thailand with a focus on scrub typhus assessment

The epidemiology of many rodent‐borne diseases in South‐East Asia remains ill‐defined. Scrub typhus and lep‐tospirosis are common and medically significant, while other zoonotic diseases, such as spotted fever group Rickettsiae have been identified, but their overall medical significance is unknown. Rodent surveillance was conducted from June 2002 to July 2004 in 18 provinces from Thailand. Traps were set up for one to three nights. Blood and serum samples and animal tissue samples (liver, spleen, kidney and urinary bladder) were collected. Chiggermites, ticks and fleas were removed from captured rodents. A total of 4536 wild‐caught rodents from 27 species were captured over two years of animal trapping. Rattus rattus was the dominant species, followed by Rattus exulans and Bandicota indica. Almost 43 000 ectoparasites were removed from the captured animals. Approximately 98% of the ectoparasites were chigger‐mites, of which 46% belonged to the genus Leptotrombidium (scrub typhus vector). Other genera included Schoengastia and Blankaartia. Tick and flea specimens together comprised less than 1% of the sample. Among the five species of ticks collected, Haemaphysalis bandicota was the predominant species caught, followed by Ixodes granulatus other Haemaphysalis spp., Rhipicephalus spp. and Dermacentor spp. Only two species of fleas were collected and Xenopsylla cheopis (rat flea) was the predominant species. Using both commercial diagnostic kits and in‐house molecular assays, animal tissue samples were examined and screened for zoonotic diseases. Seven zoonotic diseases were detected: scrub typhus, leptospirosis, murine typhus, tick typhus, bartonella, babesiosis and trypanosomiasis. Most samples were positive for scrub typhus. Other zoonotic diseases still under investigation include borrelosis, ehrlichiosis, the plague, and other rickettsial diseases. Using geographic information systems, global positioning systems and remote sensing technology, epidemiological and environmental data were combined to assess the relative risk in different biotopes within highly endemic areas of scrub typhus in Thailand.     

Nutrient mobilization from body tissues as influenced by litter size in lactating sows

Twenty-eight primiparous sows were used to study nutrient mobilization among body tissues as influenced by litter size in lactating sows. Litter size was set to 6, 7, 8, 9, 10, 11, or 12 pigs within 48 h postpartum by cross-fostering. Four sows were allotted to each litter size group. Sows had 11.5 +/- 1.3 Mcal of ME and 39.3 +/- 4.4 g of lysine per day and were killed on d 20.6 +/- 1.1 of lactation. Liver, gastrointestinal tract (GIT, composed of the empty stomach, empty small and large intestines, cecum and rectum), reproductive tract, and other organs (excluding liver, GIT, reproductive tract, and mammary gland) were separated from the carcass. Gastrointestinal tracts were manually stripped of contents and flushed with water to remove digesta. Hot carcasses were split longitudinally at the midline after removing mammary glands and internal organs. Individual organs and carcasses were weighed then ground for chemical analysis. Dry matter, crude protein, fat, and ash contents were measured. As litter size increased, protein mobilization was linearly increased (P < 0.05) in carcass, GIT, and reproductive tract. Protein mobilization in liver was quadratically affected by litter size (P < 0.05). Fat mobilization was not affected by litter size. The amount of protein mobilized from carcass, GIT, liver, and reproductive tract in sows increased by 641 g as litter size increased by one pig from 6 to 12 pigs after a 21-d lactation. Carcass contributed the largest amount of protein (600 g for an additional pig) among body tissues, whereas the reproductive tract contributed the highest percentage (26%) of its protein among body tissues. Protein efficiency from milk to litter weight gain was 72% as litter size increased during a 21-d lactation. In feeding lactating sows, effect of litter size on nutrient mobilization from various tissues should be considered for minimizing the excess tissue mobilization during lactation.     

Yersinia pestis: examining wildlife plague surveillance in China and the USA

Plague is a zoonotic disease caused by the bacterium Yersinia pestis Lehmann and Neumann, 1896. Although it is essentially a disease of rodents, plague can also be transmitted to people. Historically, plague has caused massive morbidity and mortality events in human populations, and has recently been classified as a reemerging disease in many parts of the world. This public health threat has led many countries to set up wild and domestic animal surveillance programs in an attempt to monitor plague activity that could potentially spill over into human populations. Both China and the USA have plague surveillance programs in place, but the disease dynamics differ in each country. We present data on plague seroprevalence in wildlife and review different approaches for plague surveillance in the 2 countries. The need to better comprehend plague dynamics, combined with the fact that there are still several thousand human plague cases per year, make well-designed wildlife surveillance programs a critical part of both understanding plague risks to humans and preventing disease outbreaks in the future.     

Adaptive strategies of Yersinia pestis to persist during inter-epizootic and epizootic periods

Plague is a flea-borne zoonotic bacterial disease caused by Yersinia pestis. It has caused three historical pandemics, including the Black Death which killed nearly a third of Europe's population in the 14th century. In modern times, plague epizootics can extirpate entire susceptible wildlife populations and then disappear for long time periods. Understanding how Y. pestis is maintained during inter-epizootic periods and the factors responsible for transitioning to epizootics is important for preventing and controlling pathogen transmission and ultimately reducing the burden of human disease. In this review, we focus primarily on plague in North American foci and discuss the potential adaptive strategies Y. pestis might employ to ensure not only its survival during inter-epizootic periods but also the rapid epizootic spread and invasion of new territories that are so characteristic of plague and have resulted in major pandemics and establishment of plague foci throughout much of the world.     

Best Practices for Planning Events Encouraging Human–Animal Interactions

Educational events encouraging human–animal interaction include the risk of zoonotic disease transmission. It is estimated that 14% of all disease in the USA caused by Campylobacter spp., Cryptosporidium spp., Shiga toxin‐producing Escherichia coli (STEC) O157, non‐O157 STECs, Listeria monocytogenes, non‐typhoidal Salmonella enterica and Yersinia enterocolitica were attributable to animal contact. This article reviews best practices for organizing events where human–animal interactions are encouraged, with the objective of lowering the risk of zoonotic disease transmission.     

Microbiological Contamination of Reindeer Carcass During Slaughter

Microbiological counts for 10 different sampling sites of 28 reindeer carcasses were studied in 3 reindeer slaughterhouses in Finland. On each carcass the hindshank, round, abdomen, flank, brisket, foreleg, shoulder, neck, foreback and back were sampled immediately after slaughter, using a nondestructive swabbing method. The overall mean bacterial count for 10 sampling sites of reindeer carcasses was 1.51 ± 0.51 log₁₀ cfu/cm². Statistically significant differences were detected between sampling sites. The back part of the reindeer carcass, i.e. hindshank, round, back and foreback, seemed to be relatively clean. The most contaminated parts were the foreleg, brisket and abdomen (2.05–2.95 log₁₀ cfu/cm²); these could be used for monitoring the hygiene of the reindeer carcass after slaughter. Differences between the 3 slaughterhouses were detected for some sampling sites, which may be due to differences in slaughter techniques and hygiene.     

City sanitation and socioeconomics predict rat zoonotic infection across diverse neighbourhoods

Rat‐associated zoonoses transmitted through faeces or urine are of particular concern for public health because environmental exposure in homes and businesses may be frequent and undetected. To identify times and locations with greater public health risks from rats, we investigated whether rat characteristics, environmental features, socioeconomic factors, or season could predict rat infection risk across diverse urban neighbourhoods. In partnership with a pest management company, we sampled rats in 13 community areas along an income gradient in Chicago, a large city where concern about rats has increased in recent years. We collected kidneys for Leptospira spp. testing and colon contents for aerobic bacteria such as Salmonella spp. and Escherichia coli. Of 202 sampled rats, 5% carried Leptospira spp. and 22% carried E. coli. Rats were significantly more likely to carry Leptospira spp. on blocks with more standing water complaints in higher‐income neighbourhoods (OR = 6.74, 95% CI: 1.54–29.39). Rats were significantly more likely to carry E. coli on blocks with more food vendors (OR = 9.94, 2.27–43.50) particularly in low‐income neighbourhoods (OR = 0.26, 0.09–0.82) and in the spring (OR = 15.96, 2.90–88.62). We detected a high diversity of E. coli serovars but none contained major virulence factors. These associations between environmental features related to sanitation and infection risk in rats support transmission through water for Leptospira spp. and faecal–oral transmission for E. coli. We also found opposing relationships between zoonotic infection risk and income for these two pathogens. Thus, our results highlight the importance of sanitation for predicting zoonotic disease risks and including diverse urban areas in pathogen surveillance to mitigate public health risks from rats.     

Field assessment of dog as sentinel animal for plague in endemic foci of Madagascar

The epidemiology of Yersinia pestis, the causative agent of plague, involves vectors and reservoirs in its transmission cycle. The passive plague surveillance in Madagascar targets mainly rodent and fleas. However, carnivores are routinely surveyed as sentinels of local plague activity in some countries. The aim of this study is to assess the use of domestic dog (Canis familiaris) as sentinel animal for field surveillance of plague in a highly endemic area in Madagascar. Cross-sectional surveys of plague antibody prevalence in C. familiaris were conducted in endemic areas with contrasting histories of plague cases in humans, as well as a plague free area. Rodent capture was done in parallel to evaluate evidence for Y. pestis circulation in the primary reservoirs. In 2 sites, dogs were later re-sampled to examine evidence of seroconversion and antibody persistence. Biological samplings were performed between March 2008 and February 2009. Plague antibody detection was assessed using anti-F1 ELISA. Our study showed a significant difference in dog prevalence rates between plague-endemic and plague-free areas, with no seropositive dogs detected in the plague free area. No correlation was found between rodents and dog prevalence rates, with an absence of seropositive rodents in some area where plague circulation was indicated by seropositive dogs. This is consistent with high mortality rates in rodents following infection. Re-sampling dogs identified individuals seropositive on both occasions, indicating high rates of re-exposure and/or persistence of plague antibodies for at least 9 months. Seroconversion or seropositive juvenile dogs indicated recent local plague circulation. In Madagascar, dog surveillance for plague antibody could be useful to identify plague circulation in new areas or quiescent areas within endemic zones. Within active endemic areas, monitoring of dog populations for seroconversion (negative to positive) or seropositive juvenile dogs could be useful for identifying areas at greatest risk of human outbreaks.     

Risk-based cost modelling of oral rabies vaccine interventions for raccoon rabies

Distribution of oral rabies vaccine (ORV) is an effective but costly strategy to control raccoon rabies. Because of high costs, ORV for raccoon rabies in the U.S. has been limited primarily to epizootic areas, leaving extensive raccoon rabies regions without any ORV intervention. Several cost scenarios for ORV application in raccoon rabies enzootic and epizootic regions were modelled in New York State to obtain estimated costs of ORV baits per scenario and potential savings compared with a uniform ORV baiting strategy. These cost scenarios modelled at the census tract, level the application of ORV baits at different densities according to levels of risk defined by the observed number of raccoon rabies cases per km2 and the expected number of cases per km2 estimated with a Poisson regression model. Bait purchase costs were lower using the modelled cost scenarios than a uniform baiting strategy, for both the NYS enzootic region and the Long Island epizootic zone. The proportion of savings for the NYS enzootic region was 29.57%, and the proportion of savings for the Long Island epizootic zone was 38.9%. Use of these cost scenarios to determine bait distribution by rabies risk level should be considered to maximize efficacy and reduce costs of ORV interventions.     

Ovarian follicle development and genital tract characteristics in different birthweight gilts at 150 days of age

In the last decades, selection for improved prolificacy has resulted in higher litter sizes and has thereby increased the proportion of low birthweight (LW) piglets. It is well documented that LW piglets have lower growth performance, muscle accretion and poor carcass quality. However, little is known about the relations of birthweight with subsequent reproductive performance in gilts. This study investigated the effects of birthweight on reproductive tract and ovarian follicle development in 150‐day‐old gilts. Twenty eight female pigs of different birthweight ranges (high‐HW: 1.8–2.2 kg; low‐LW: 0.8–1.2 kg) from higher parity commercial sows were reared until 150 days of age, and their body weights were recorded at weaning, end of nursery and end of the grower‐finisher phase. The animals were killed and their reproductive tracts collected for biometrical and histomorphometrical analysis. LW gilts showed significantly lower body weights and growth rates during all phases of production compared to their HW counterparts (p < .01). Most biometrical measurements of the reproductive tract were similar between the experimental groups, except vaginal length and the gonadossomatic index (relative ovarian weight), which were affected by birthweight class (p < .05). LW females also showed fewer medium size (3–5 mm; p < .01) ovarian follicles, pre‐antral follicles (p < .07) and more atretic follicles per ovarian cortex area (p < .05). Therefore, besides the effects on post‐natal growth performance, birthweight affects vaginal length and the follicular dynamics process, which may impair the reproductive performance of replacement gilts.