Rodents as a Source of Salmonella Contamination in Wet Markets in Thailand

Emerging zoonotic diseases in Southeast Asia in the period 2011-2022: a systematic literature review

As COVID-19 has shown, pandemics and outbreaks of emerging infections such as Zika, Nipah, monkeypox and antimicrobial-resistant pathogens, especially emerging zoonotic diseases, continue to occur and may even be increasing in Southeast Asia. In addition, these infections often result from environmental changes and human behaviour. Overall, public health surveillance to identify gaps in the literature and early warning signs are essential in this region. A systematic review investigated the prevalence of emerging zoonotic diseases over 11 years from 2011 to 2022 in Southeast Asia to understand the status of emerging zoonotic diseases, as well as to provide necessary actions for disease control and prevention in the region. During the 2011-2022 period, studies on pigs, poultry, ruminants, companion animals and wildlife in Southeast Asia were reviewed thoroughly to assess the quality of reporting items for inclusion in the systematic review. The review was performed on 26 studies of pigs, 6 studies of poultry, 21 studies of ruminants, 28 studies of companion animals and 25 studies of wildlife in Southeast Asia, which provide a snapshot of the prevalence of the emerging zoonotic disease across the country. The findings from the review showed that emerging zoonotic diseases were prevalent across the region and identified a few zoonotic diseases associated with poultry, mainly stemming from Cambodia and Vietnam, as high priority in Southeast Asia.Clinical relevance: Appropriate prevention and control measures should be taken to mitigate the emerging zoonotic diseases in Southeast Asia.

Low Occurrence of Salmonella spp. in Wild Animals in Bahia, Brazil-Population Assessment and Characterization in the Caatinga and Atlantic Forest Biomes

Salmonella spp. are known to persist in the environment. Wild animals are believed to act as important reservoirs, with antimicrobial resistance frequently occurring in the environment. However, little is known about the role of the wildlife in Bahia as a reservoir for Salmonella in Brazil. This study aimed to isolate and characterize Salmonella spp. from wildlife in the Atlantic Forest and Caatinga biomes considering indicators such as the animal species, degree of anthropization, sampling area, and feeding habits. Convenience wildlife sampling and characterization were conducted, followed by microbiological and molecular identification of Salmonella isolates, serotyping, and antimicrobial susceptibility testing. A total of 674 fecal samples were collected from 12 municipalities during 2015-2021, and 4 were positive for the following Salmonella species: Salmonella enterica subspecies enterica serovar Agona (n = 1), Salmonella enterica subsp. enterica serogroup O:16 (n = 2), and Salmonella enterica subsp. enterica serovar Muenchen (n = 1). Antimicrobial susceptibility analysis revealed that one isolate was resistant to six antibiotics, including extended-spectrum penicillins and beta-lactamase inhibitors. These results indicated a low frequency of Salmonella spp. in the sampled forest fragments. The presence of Salmonella in wild animals increases the risk to public health and biodiversity and indicates that they can act as sentinels of environmental contamination or indicators of preservation.

Avoiding novel, unwanted interactions among species to decrease risk of zoonoses

Circumstances that precipitate interactions among species that have never interacted during their evolutionary histories create ideal conditions for the generation of zoonoses. Zoonotic diseases have caused some of the most devastating epidemics in human history. Contact among species that come from different ecosystems or regions creates the risk of zoonoses. In certain situations, humans are generating and promoting conditions that contribute to the creation of infectious diseases and zoonoses. These conditions lead to interactions between wildlife species that have hitherto not interacted under normal circumstances. I call for recognition of the zoonotic potential that novel and unwanted interactions have; identification of these new interactions that are occurring among wild animals, domestic animals, and humans; and efforts to stop these kinds of interactions because they can give rise to zoonotic outbreaks. Live animal markets, the exotic pet trade, illegal wildlife trade, human use and consumption of wild animals, invasive non-native species, releasing of exotic pets, and human encroachment in natural areas are among the activities that cause the most interactions among wild species, domestic species, and humans. These activities should not occur and must be controlled efficiently to prevent future epidemic zoonoses. Society must develop a keen ability to identify these unnatural interactions and prevent them. Controlling these interactions and efficiently addressing their causal factors will benefit human health and, in some cases, lead to positive environmental, ethical, and socioeconomic outcomes. Until these actions are taken, humanity will face future zoonoses and zoonotic pandemic.

Increased rat-borne zoonotic disease hazard in greener urban areas

Urban greening has benefits for both human and environmental health. However, urban greening might also have negative effects as the abundance of wild rats, which can host and spread a great diversity of zoonotic pathogens, increases with urban greenness. Studies on the effect of urban greening on rat-borne zoonotic pathogens are currently unavailable. Therefore, we investigated how urban greenness is associated with rat-borne zoonotic pathogen prevalence and diversity, and translated this to human disease hazard. We screened 412 wild rats (Rattus norvegicus and Rattus rattus) from three cities in the Netherlands for 18 different zoonotic pathogens: Bartonella spp., Leptospira spp., Borrelia spp., Rickettsia spp., Anaplasma phagocytophilum, Neoehrlichia mikurensis, Spiroplasma spp., Streptobacillus moniliformis, Coxiella burnetii, Salmonella spp., methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum beta-lactamase (ESBL)/AmpC-producing Escherichia coli, rat hepatitis E virus (ratHEV), Seoul orthohantavirus, Cowpox virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Toxoplasma gondii and Babesia spp. We modelled the relationships between pathogen prevalence and diversity and urban greenness. We detected 13 different zoonotic pathogens. Rats from greener urban areas had a significantly higher prevalence of Bartonella spp. and Borrelia spp., and a significantly lower prevalence of ESBL/AmpC-producing E. coli and ratHEV. Rat age was positively correlated with pathogen diversity while greenness was not related to pathogen diversity. Additionally, Bartonella spp. occurrence was positively correlated with that of Leptospira spp., Borrelia spp. and Rickettsia spp., and Borrelia spp. occurrence was also positively correlated with that of Rickettsia spp. Our results show an increased rat-borne zoonotic disease hazard in greener urban areas, which for most pathogens was driven by the increase in rat abundance rather than pathogen prevalence. This highlights the importance of keeping rat densities low and investigating the effects of urban greening on the exposure to zoonotic pathogens in order to make informed decisions and to take appropriate countermeasures preventing zoonotic diseases.

Zoonoses in a changing world

Animals are continuously exposed to pathogens but rarely get infected, because pathogens must overcome barriers to establish successful infections. Ongoing planetary changes affect factors relevant for such infections, such as pathogen pressure and pathogen exposure. The replacement of wildlife with domestic animals shrinks the original host reservoirs, whereas expanding agricultural frontiers lead to increased contact between natural and altered ecosystems, increasing pathogen exposure and reducing the area where the original hosts can live. Climate change alters species' distributions and phenology, pathogens included, resulting in exposure to pathogens that have colonized or recolonized new areas. Globalization leads to unwilling movement of and exposure to pathogens. Because people and domestic animals are overdominant planetwide, there is increased selective pressure for pathogens to infect them. Nature conservation measures can slow down but not fully prevent spillovers. Additional and enhanced surveillance methods in potential spillover hotspots should improve early detection and allow swifter responses to emerging outbreaks.

Urban rats as carriers of invasive Salmonella Typhimurium sequence type 313, Kisangani, Democratic Republic of Congo

Background

Invasive non-typhoidal Salmonella (iNTS–mainly serotypes Enteritidis and Typhimurium) are major causes of bloodstream infections in children in sub-Saharan Africa, but their reservoir remains unknown. We assessed iNTS carriage in rats in an urban setting endemic for iNTS carriage and compared genetic profiles of iNTS from rats with those isolated from humans.

Methodology/Principal findings

From April 2016 to December 2018, rats were trapped in five marketplaces and a slaughterhouse in Kisangani, Democratic Republic of the Congo. After euthanasia, blood, liver, spleen, and rectal content were cultured for Salmonella. Genetic relatedness between iNTS from rats and humans—obtained from blood cultures at Kisangani University Hospital—was assessed with multilocus variable-number tandem repeat (VNTR) analysis (MLVA), multilocus sequence typing (MLST) and core-genome MLST (cgMLST). 1650 live-capture traps yielded 566 (34.3%) rats (95.6% Rattus norvegicus, 4.4% Rattus rattus); 46 (8.1%) of them carried Salmonella, of which 13 had more than one serotype. The most common serotypes were II.42:r:- (n = 18 rats), Kapemba (n = 12), Weltevreden and Typhimurium (n = 10, each), and Dublin (n = 8). Salmonella Typhimurium belonged to MLST ST19 (n = 7 rats) and the invasive ST313 (n = 3, isolated from deep organs but not from rectal content). Sixteen human S. Typhimurium isolates (all ST313) were available for comparison: MLVA and cgMLST revealed two distinct rat-human clusters involving both six human isolates, respectively, i.e. in total 12/16 human ST313 isolates. All ST313 Typhimurium isolates from rats and humans clustered with the ST313 Lineage 2 isolates and most were multidrug resistant; the remaining isolates from rats including S. Typhimurium ST19 were pan-susceptible.

Conclusion

The present study provides evidence of urban rats as potential reservoirs of S. Typhimurium ST313 in an iNTS endemic area in sub-Saharan Africa.

Dadi (°1974, DR Congo) is a Medical Doctor (Kisangani University 2005) with a master in pediatrics (Kisangani University 2015) with special interest in infectious diseases and tropical medicine. He has 11 years of field research experience. He was team member of scientific expedition “Boyekoli Ebale Congo” in 2010 as medical support for the researchers. He conducted work field in a multidisciplinary framework with biologists from faculty of sciences (university of Kisangani) exploring zoonotic diseases in several places in the Congo. Currently, he is doing his PhD research at KU Leuven and Institute of Tropical Medicine Antwerp (ITM), Belgium. Passionate about transmissible diseases, Dadi is exploring the potential reservoirs of non-typhoidal Salmonella in Kisangani, DR Congo.

Prevalence and Multidrug Resistance of Salmonella in Swine Production Chain in a Central Province, Thailand

ABSTRACT

Salmonella causes foodborne disease outbreaks worldwide and raises concerns about public health and economic losses. To determine prevalence, serovar, antimicrobial resistance patterns, and the presence of extended-spectrum β-lactamase (ESBL) genes in a cross-sectional study, 418 total samples from feces and carcasses (from three slaughterhouses) and pork and cutting boards (from four markets) were collected in a central Thailand province in 2017 and 2018. Of the 418 samples, 272 (65.1%) were positive for Salmonella. The prevalence of Salmonella-positive samples from markets (158 of 178; 88.8%) was significantly higher than that among samples from slaughterhouses (114 of 240; 47.5%) (P < 0.05). A total of 1,030 isolates were identified; 409 were assigned to 45 serovars, with Salmonella Rissen the most common (82 of 409; 20%). Two serovars, Salmonella Cannstatt and Salmonella Braubach, were identified for the first time in Thailand in market and slaughterhouse samples, respectively. Among 180 isolates representing 19 serovars, 133 (73.9%) exhibited multidrug resistance. Screening for ESBL production revealed that 41 (10.3%) of 399 isolates were ESBL positive. The prevalence of ESBL-producing Salmonella isolates was significantly higher among the market isolates (31 of 41; 75.6%) than among the slaughterhouse isolates in (10 of 41; 24.4%) (P < 0.05). In market samples, 24 (77.4%) of 31 isolates were recovered from pork and 7 (22.6%) were recovered from cutting boards. Nine ESBL-producing isolates carried single ESBL genes, either blaTEM (4 of 41 isolates; 9.8%) or blaCTX-M (5 of 41 isolates; 12.2%), whereas 11 (26.8%) carried both blaTEM and blaCTX-M. No ESBL-producing Salmonella isolate carried the blaSHV gene. These results suggest that pigs, their flesh, and cutting boards used for processing pork could be reservoirs for widespread ESBL-producing Salmonella isolates with multidrug resistance and outbreak potential across the food chain.

HIGHLIGHTS

Zoonotic potential and prevalence of Salmonella serovars isolated from pets

Salmonellosis is a global health problem, affecting approximately 1.3 billion people annually. Most of these cases are related to food contamination. However, although the majority of Salmonella serovars are pathogenic to humans, animals can be asymptomatic carriers of these bacteria. Nowadays, a wide range of animals is present in human households as pets, including reptiles, amphibians, dogs, cats, ornamental birds, and rodents. Pets contaminate the environment of their owners by shedding the bacteria intermittently in their feaces. In consequence, theyare thought to cause salmonellosis through pet-to-human transmission. Each Salmonella serovar has a different zoonotic potential, which is strongly regulated by stress factors such as transportation, crowding, food deprivation, or temperature. In this review, we summarize the latest reports concerning Salmonella-prevalence and distribution in pets as well as the risk factors and means of prevention of human salmonellosis caused by contact with their pets. Our literature analysis (based on PubMed and Google Scholar databases) is limited to the distribution of Salmonella serovars found in commonly owned pet species. We collected the recent results of studies concerning testing for Salmonella spp. in biological samples, indicating their prevalence in pets, with regard to clinical cases of human salmonellosis.

Magnitude, risk factors and antimicrobial susceptibility pattern of Shigella and Salmonella, among children with diarrhea in Southern Ethiopia: A Cross-sectional Study

Objective:

This study was aimed at identifying Shigella and Salmonella infection, their antibiotic susceptibility pattern and associated risk factors among children with diarrhea who attended Alamura Health Center.

Method:

A facility-based cross-sectional study was conducted on 263 children aged below 14 years with diarrhea. A structured questionnaire was used to collect socio-demographic and clinical data after obtaining the necessary consent from their parents or caretakers. The culture and sensitivity tests were performed using the standard operating procedure of the microbiology laboratory.

Results:

Accordingly, 20/263 (7.6%), 95% confidence interval: 4.4%–11.4% Shigella and 1/263 (0.38%), 95% confidence interval: 0.0%–1.1% Salmonella were isolated. Shigella dysenteriae was dominant 11 (4.2%), followed by Shigella spp. 9 (3.42%) and Salmonella typ 1 (0.38%). The isolates showed 71.4% overall resistance to ampicillin and 61.9% for augmentin and tetracycline, whereas 95.2% of the isolates were sensitive to ciprofloxacin, 85.9% to ceftriaxone and ceftazidime, 81% to gentamycin, 76.2% to chloramphenicol, 66.7% to cefuroxime and 52.4% to cotrimoxazole. The habit of washing hands after toilet use for a while (adjusted odds ratio: 235.1, 95% confidence interval: 20.9–2643.3, p < 0.000) and storing cooked food in an open container for later use (adjusted odds ratio: 36.44, 95% confidence interval: 5.82–228.06, p < 0.000) showed a statistically significant association.

Conclusion:

High level of Shigella and single Salmonella was isolated. Ampicillin, augmentin and tetracycline were resistant and ciprofloxacin, ceftriaxone, ceftazidime, gentamycin, chloramphenicol, cefuroxime and cotrimoxazole were relatively sensitive. Hand-washing after defecation for some time and storing of foods for later use in an open container were statistically associated. Therefore, to alleviate this infection, the concerned body should focus on imparting health education for hand-wash after defecation and storing food in a closed container for later use is mandatory.

Insects, Rodents, and Pets as Reservoirs, Vectors, and Sentinels of Antimicrobial Resistance

This paper reviews the occurrence of antimicrobial resistance (AMR) in insects, rodents, and pets. Insects (e.g., houseflies, cockroaches), rodents (rats, mice), and pets (dogs, cats) act as reservoirs of AMR for first-line and last-resort antimicrobial agents. AMR proliferates in insects, rodents, and pets, and their skin and gut systems. Subsequently, insects, rodents, and pets act as vectors that disseminate AMR to humans via direct contact, human food contamination, and horizontal gene transfer. Thus, insects, rodents, and pets might act as sentinels or bioindicators of AMR. Human health risks are discussed, including those unique to low-income countries. Current evidence on human health risks is largely inferential and based on qualitative data, but comprehensive statistics based on quantitative microbial risk assessment (QMRA) are still lacking. Hence, tracing human health risks of AMR to insects, rodents, and pets, remains a challenge. To safeguard human health, mitigation measures are proposed, based on the one-health approach. Future research should include human health risk analysis using QMRA, and the application of in-silico techniques, genomics, network analysis, and ’big data’ analytical tools to understand the role of household insects, rodents, and pets in the persistence, circulation, and health risks of AMR.

Multidrug-Resistant Salmonella enterica Isolated in Paca (Cuniculus paca) Carcasses from the Belen Market, Iquitos, Perú

The consumption of wildlife meat is traditionally accepted in the Peruvian Amazon; however, little is known about the pathogens present in this type of food. One of the most frequently consumed species is a rodent, the paca (Cuniculus paca) or "majaz" in the Peruvian language. The objective of this study was to determine the presence of Salmonella enterica and its antimicrobial resistance profile in paca carcasses sold in the Belen Market of Iquitos-Peru. An observational, descriptive, cross-sectional study was carried out. Fresh and smoked paca carcasses (72 samples) were evaluated during the low-rain period (July 2019) in the traditional market of Iquitos, in the Amazonian Region. Meat samples were swabbed, and International Standards Organization (ISO) 6579-1: 2017 protocol was followed to Salmonella isolation. Antimicrobial susceptibility analysis was performed by the disk diffusion method. In addition, serotyping was performed by using the Kauffmann-White scheme. A total of 25 strains of S. enterica were isolated in the paca carcasses, mainly in fresh carcasses (48.6%). The serovars isolated were Agona (45.8%), Infantis (41.7%), Wangata (8.3%), and Javiana (4.2%). A considerable number of the isolated strains were multidrug resistant (40%). The highest prevalence of resistance corresponded to trimethoprim-sulfamethoxazole (64%) followed by nitrofurantoin (44%), chloramphenicol (40%), cefotaxime (40%), and nalidixic acid (40%). Ten strains isolated (40%) were identified as producers of extended spectrum beta lactamases, all in S. enterica serovar Infantis. This study describes the presence of Salmonella Infantis with multidrug resistance profiles in wildlife meat carcasses, making the consumption of this type of products a risk factor for the development of foodborne diseases in the Amazon region. Institutional Review Board: Approval Resolution of Thesis Project: N° 024-DACMVZ-DAFCVB-U.CIENTÍFICA-2019.

Sociocultural, behavioural and political factors shaping the COVID-19 pandemic: the need for a biocultural approach to understanding pandemics and (re)emerging pathogens

Although there has been increasing focus in recent years on interdisciplinary approaches to health and disease, and in particular the dimension of social inequalities in epidemics, infectious diseases have been much less focused on. This is especially true in the area of cultural dynamics and their effects on pathogen behaviours, although there is evidence to suggest that this relationship is central to shaping our interactions with infectious disease agents on a variety of levels. This paper makes a case for a biocultural approach to pandemics such as COVID-19. It then uses this biocultural framework to examine the anthropogenic dynamics that influenced and continue to shape the COVID-19 pandemic, both during its initial phase and during critical intersections of the pandemic. Through this understanding of biocultural interactions between people, animals and pathogens, a broader societal and political dimension is drawn as a function of population level and international cultures, to reflect on the culturally mediated differential burden of the pandemic. Ultimately, it is argued that a biocultural perspective on infectious disease pandemics will allow for critical reflection on how culture shapes our behaviours at all levels, and how the effects of these behaviours are ultimately foundational to pathogen ecology and evolution.

PCR-based detection and serovar identification of Salmonella in retail meat collected from wet markets in Metro Manila, Philippines

This study aimed to detect Salmonella from retail meat collected from nine wet markets in Metro Manila, and identify the subtypes of Salmonella isolates using molecular serotyping assays from previously developed primers. Of the 720 collected meat samples, 57.64% were found to be Salmonella-contaminated. The most predominant serogroup was Salmonella O:3, and Salmonella serogroups O:4, O:6,7, O:8, O:9, and undetermined serogroups were also found. Most frequently detected isolates in bovine meat were S. 3:e,h:1,6 (putative identity: S. Anatum) and S: 4:e,h:1,2 (putative identity: S. Saintpaul), in porcine meat was S. 3:e,h:1,6 (putative identity: S. Anatum), and S. 8:i:z6 (putative identity: S. Kentucky) was common in poultry products. This study also demonstrated retail meat samples were contaminated with multiple Salmonella serogroups and serovars. This is the first Philippine study that utilized PCR-based assays to characterize Salmonella isolates down to a serovar level and provides baseline information regarding Salmonella prevalence and serovar distribution in retail meat. Molecular serotyping performed in this study can be used as an alternative approach to traditional serotyping in surveillance of Salmonella in the Philippines since the latter is expensive, time-consuming, and requires skilled technicians.

Salmonella and Antimicrobial Resistance in Wild Rodents-True or False Threat?

Transmission of pathogenic and resistant bacteria from wildlife to the bacterial gene pool in nature affects the ecosystem. Hence, we studied intestine content of five wild rodent species: the yellow-necked wood mouse (Apodemus flavicollis, n = 121), striped field mouse (Apodemus agrarius, n = 75), common vole (Microtus arvalis, n = 37), bank vole (Myodes glareolus, n = 3), and house mouse (Mus musculus, n = 1) to assess their potential role as an antimicrobial resistance (AMR) and Salmonella vector. The methods adopted from official AMR monitoring of slaughtered animals were applied and supplemented with colistin resistance screening. Whole-genome sequencing of obtained bacteria elucidated their epidemiological relationships and zoonotic potential. The study revealed no indications of public health relevance of wild rodents from the sampled area in Salmonella spread and their limited role in AMR dissemination. Of 263 recovered E. coli, the vast majority was pan-susceptible, and as few as 5 E. coli showed any resistance. In four colistin-resistant strains neither the known mcr genes nor known mutations in pmr genes were found. One of these strains was tetracycline-resistant due to tet(B). High diversity of virulence factors (n = 43) noted in tested strains including ibeA, cdtB, air, eilA, astA, vat, pic reported in clinically relevant types of enteric E. coli indicate that rodents may be involved in the ecological cycle of these bacteria. Most of the strains represented unique sequence types and ST10805, ST10806, ST10810, ST10824 were revealed for the first time, showing genomic heterogeneity of the strains. The study broadened the knowledge on phylogenetic diversity and structure of the E. coli population in wild rodents.

Salmonella in native "village" chickens (Gallus domesticus): prevalence and risk factors from farms in South-Central Peninsular Malaysia

Village chicken or Ayam Kampung, common to Southeast Asian countries, has always been regarded as superior in comparison to commercial broiler chicken in terms of wholesomeness and health benefits. The current study investigates the prevalence and risk factors of Salmonella among village chicken flocks from the central and southern states of Peninsular Malaysia. A total of 35 village flocks were sampled from Selangor (n = 19), Melaka (n = 10), Johor (n = 4), and Negeri Sembilan (n = 2). In total, 1,042 samples were collected; these included cloacal swabs (n = 675), eggs (n = 62), pooled drinking water (n = 175), pooled feeds (n = 70), and pooled flies (n = 60). Isolation of Salmonella from cloacal swabs, poultry drinking water, and feeds was carried out according to the protocols and recommendations of the World Organization for Animal Health (OIE) terrestrial manual. The prevalence of Salmonella at an individual bird-level was 2.5% (17/675, 95% CI: 1.6 to 4.0). All eggs screened were negative; in the case of environmental samples, however, Salmonella was detected in 5.14% (9/175), 7.14% (5/70), and 5.0% (3/60) for water, feed, and flies, respectively. A total of 34 isolates and 8 Salmonella serotypes were identified. Weltevreden (20.6%) was the most common, followed by Typhimurium and Agona (17.6%), Albany and Enteritidis (8.8%), Molade (5.9%), Corvallis and Schleissheim (2.9%), and others grouped as Salmonella spp. (11.8%). Multivariable logistic regression models revealed that Salmonella positivity among flocks could be strongly predicted by storage of feeds (uncovered feeds; OR = 10.38; 95% CI: 1.25 to 86.39; p = 0.030) and uncovered water tanks (uncovered tank; OR = 6.43; 95% CI: 1.02 to 40.60; p = 0.048). The presence of Salmonella in village chickens in the study area was lower than that of commercial chickens in Malaysia.

Infection, colonization and shedding of Campylobacter and Salmonella in animals and their contribution to human disease: A review

Livestock meat and offal contribute significantly to human nutrition as sources of high-quality protein and micronutrients. Livestock products are increasingly in demand, particularly in low- and middle-income settings where economies are growing and meat is increasingly seen as an affordable and desirable food item. Demand is also driving intensification of livestock keeping and processing. An unintended consequence of intensification is increased exposure to zoonotic agents, and a contemporary emerging problem is infection with Campylobacter and Salmonella spp. from livestock (avian and mammalian), which can lead to disease, malabsorption and undernutrition through acute and chronic diarrhoea. This can occur at the farm, in households or through the food chain. Direct infection occurs when handling livestock and through bacteria shed into the environment, on food preparation surfaces or around the house and surroundings. This manuscript critically reviews Campylobacter and Salmonella infections in animals, examines the factors affecting colonization and faecal shedding of bacteria of these two genera as well as risk factors for human acquisition of the infection from infected animals or environment and analyses priority areas for preventive actions with a focus on resource-poor settings.

Antimicrobial Resistance of Salmonella spp. Isolates and Heavy Metal Traces from Rodent Meat Purchased from Roadside Markets, Central Thailand

Although game meat consumption is widespread across the globe, involving a great diversity of species in very different ecological and sociocultural environments, the safety of wild meat products is rarely assessed routinely. We conducted a survey to evaluate the safety of two rodents products (Rattus tanezumi and Bandicota indica) purchased from roadside markets in central Thailand. Total aerobic bacteria and Escherichia coli counts measured were above Thai poultry product standards for 83.3% and 100% of the samples, respectively (n = 108), although there was no difference between rat species (analysis of variance [ANOVA], p > 0.05). Salmonella spp. were isolated from 32% of the swabs collected (67/208), including 19 different serovars. All strains were resistant or partially resistant to at least 2 of the 16 antibiotics tested, with levels of resistance varying greatly among antibiotics (e.g., 97% of strains sensitive to ciprofloxacin and 98.5% of strains resistant to cloxacillin). Detectable traces of Cd and Pb were found in 98% and 46% of the samples analyzed, respectively (n = 61). Pb and Cd concentrations measured in the kidneys of R. tanezumi were significantly higher than in the liver and muscles and significantly higher than B. indica muscles and kidneys but not liver (ANOVA, p < 0.05). These results highlight potential health hazards that may be associated with rodent-meat consumption, including contamination by coliform bacteria, multiresistant Salmonella spp. strains, and heavy metals. The significance of these results for public health cannot be determined precisely in the absence of appropriate standards, and information gaps remain regarding the frequency of rodent-meat consumption and the origin of bacterial and heavy metal contaminations (i.e., capture environment or during carcass handling and processing). We suggest that appropriate information and training on best hygienic practices for preparing, cooking, and preserving rodent meat should be provided to the producers and to the consumers.

Helminths in rodents from Wet Markets in Thailand

Only a few surveys have ever been carried out of the helminths of the commensal rodents found in the traditional wet markets that play such an important part of daily life in South-east Asia. The potential of rodents as reservoirs of zoonoses including helminths is of great interest since in these markets humans and rodents come into closer contact than in other environments and food may be indirectly contaminated via rodent faeces. Helminths in a total of 98 rats belonging to two species (Rattus norvegicus and Rattus exulans) were surveyed in eight traditional wet markets in Udon Thani, Thailand. Thirteen species of helminths were recovered, seven of which are potentially zoo-notic, with an overall prevalence of 89.8 %. Our results show that rodents in wet markets could pose a threat to human health as potential reservoirs of zoonotic helminthiases.