Food-borne Zoonosis Research Articles

Foodborne zoonoses control in low- and middle-income countries: Identifying aspects of interventions relevant to traditional markets which act as hurdles when mitigating disease transmission

Globally, foodborne zoonoses are responsible for approximately one third of all foodborne disease burden and this picture is likely to worsen if consumption of animal source foods continues to rise with insufficient attention to risk mitigation. Traditional markets represent highly important nodes that can be targeted for risk mitigation; in this series of case studies, we discuss food safety interventions relevant to this nexus. We illustrate that to improve food safety within traditional markets it is essential to consider some of the motivations and incentives of the stakeholders involved and the cultural, social, and economic context in which interventions are undertaken, highlighting barriers, enablers future interventions should aim to avoid, embrace. We also conclude that a holistic approach to foodborne zoonoses control will require the institutionalization of One Health across food systems of which traditional markets are part.

Cryptosporidiosis: From Prevention to Treatment, a Narrative Review.

Cryptosporidiosis is a water- and food-borne zoonotic disease caused by the protozoon parasite of the genus Cryptosporidium. C. hominis and C. parvum are the main two species causing infections in humans and animals. The disease can be transmitted by the fecal-oral route as well as the respiratory route. The infective stage (sporulated oocysts) is resistant to different disinfectants including chlorine. Currently, no effective therapeutic drugs or vaccines are available to treat and control Cryptosporidium infection. To prevent cryptosporidiosis in humans and animals, we need to understand better how the disease is spread and transmitted, and how to interrupt its transmission cycle. This review focuses on understanding cryptosporidiosis, including its infective stage, pathogenesis, life cycle, genomics, epidemiology, previous outbreaks, source of the infection, transmission dynamics, host spectrum, risk factors and high-risk groups, the disease in animals and humans, diagnosis, treatment and control, and the prospect of an effective anti-Cryptosporidium vaccine. It also focuses on the role of the One Health approach in managing cryptosporidiosis at the animal-human-environmental interface. The summarized data in this review will help to tackle future Cryptosporidium infections in humans and animals and reduce the disease occurrence.

Surveying citizens on food safety

Surveying citizens on food safety

Seroprevalence of Specific Antibodies to Toxoplasma gondii, Neospora caninum, and Brucella spp. in Sheep and Goats in Egypt.

Toxoplasmosis, neosporosis, and brucellosis are devastating diseases causing infectious abortion and, therefore, substantial economic losses in farm animals. Toxoplasmosis and neosporosis are caused by the intracellular protozoan parasites Toxoplasma gondii (T. gondii) and Neospora caninum (N. caninum), respectively. Brucellosis is a bacterial disease caused by numerous Brucella species in multiple hosts. Toxoplasmosis and brucellosis are also considered foodborne zoonotic diseases. In the current study, specific antibodies to T. gondii and N. caninum, in addition to those to Brucella spp., were detected to gain a better understanding of the epidemiological situation for these three pathogens. Sheep and goat sera from Egypt (n = 360) of animals with and without a history of abortion were tested using commercial ELISAs. Seropositivity rates of 46.1%, 11.9%, and 8.6% for T. gondii, N. caninum, and Brucella spp., respectively, were revealed. Mixed infections with T. gondii and Brucella spp. (4.4%), T. gondii and N. caninum (4.2%), N. caninum and Brucella spp. (1.4%), and even some triple infections (0.6%) have been observed. Animals with a history of abortion had a significantly higher seroprevalence for Brucella spp. infection than those without abortion (12.6%; 28/222 vs. 2.2%; 3/138) (p = 0.0005; Odds ratio = 1.9-21.8), while none of the other pathogens showed a similar effect. This result suggests brucellosis as a possible cause of abortion in the study population. However, the high seroprevalence for T. gondii and N. caninum revealed in our study warrants further investigations.

Occurrence of Campylobacter spp. and Phenotypic Antimicrobial Resistance Profiles of Campylobacter jejuni in Slaughtered Broiler Chickens in North-Western Romania

Campylobacteriosis is recognized as one of the most common food-borne zoonoses, with worldwide distribution, having undercooked poultry meat and other cross-contaminated foodstuffs as the main sources of human infections. The current study aimed to provide data on the occurrence of the thermophilic Campylobacter spp. in seven broiler chicken flocks, from three north-western Transylvanian counties of Romania, as well as to determine the antimicrobial resistance profile of the isolated C. jejuni strains. A total of 324 fresh cecal samples were collected during the slaughtering process, and screened for the presence of Campylobacter spp., using routine microbiological and molecular diagnostic tools. Overall, 85.2% (276/324; 95% CI 80.9-88.6) of the tested samples expressed positive results for Campylobacter spp., with dominant occurrence of C. coli towards C. jejuni (63.4% vs. 36.6%). From the six tested antimicrobials, the 101 isolated C. jejuni strains were resistant against ciprofloxacin (79.2%), nalidixic acid (78.2%), tetracycline (49.5%), and streptomycin (7.9%), but total susceptibility was noticed against erythromycin and gentamicin. Seven (6.9%) isolates exhibited multidrug resistance. The study results emphasize the role of broiler chicken as reservoir of Campylobacter infections for humans, as well as strengthen the necessity of the prudent using of antimicrobials in the poultry industry.

An ensemble learning approach to identify pastured poultry farm practice variables and soil constituents that promote Salmonella prevalence

Animal sourced foods including contaminated poultry meat and eggs contribute to human non-typhoidal salmonellosis, a foodborne zoonosis. Prevalence of Salmonella in pastured poultry production systems can lead to contamination of the final product. Identification of farm practices that affect Salmonella prevalence is critical for implementing control measures to ensure the safety of these products. In this study, we developed predictive models based predominantly on deep learning approaches to identify key pre-harvest management variables (using soil and feces samples) in pastured poultry farms that contribute to Salmonella prevalence. Our ensemble approach utilizing five different machine learning techniques predicts that physicochemical parameters of the soil and feces (elements such as sodium (Na), zinc (Zn), potassium (K), copper (Cu)), electrical conductivity (EC), the number of years that the farms have been in use, and flock size significantly influence pre-harvest Salmonella prevalence. Egg source, feed type, breed, and manganese (Mn) levels in the soil/feces are other important variables identified to contribute to Salmonella prevalence on larger (≥3 flocks reared per year) farms, while pasture feed and soil carbon-to-nitrogen ratio are predicted to be important for smaller/hobby (<3 flocks reared per year) farms. Predictive models such as the ones described here are important for developing science-based control measures for Salmonella to reduce the environmental, animal, and public health impacts from these types of poultry production systems.

The NIH Climate Change and Health Initiative and Strategic Framework: addressing the threat of climate change to health

Climate change is the single greatest health hazard facing humanity, according to WHO and the UN.1 Increasing global temperatures are altering Earth's ecosystems and affecting the fundamentals of life, including access to clean and sufficient air, water, food, and shelter, with cascading impacts on human health. Extreme weather events associated with climate change are becoming more frequent and severe.2 Climate change contributes to the emergence and spread of infectious diseases, exacerbates threats to human health across various health conditions, such as respiratory and cardiovascular diseases and mental health conditions, and increases the risk of water-borne and food-borne diseases, malnutrition, vector-borne and zoonotic diseases, and extreme-weather-related morbidities and mortality.

CLIMATE CHANGES DUE TO GLOBAL WARMING AND RISKS OF EXPECTED DISEASE OUTBREAKS

Global warming is the process of rapid increase in the average annual temperature of the ground layer of the atmosphere and the world's oceans, which is due to the increase in the concentration of &lt;greenhouse gases&gt; in the atmosphere. Climate change is causing more frequent extreme weather events such as extreme heat waves, hurricanes and floods. This is related to the disorganization of food supply to the population. Food-borne zoonotic diseases, contaminated water-related illnesses, communicable diseases, and mental disorders are also on the rise. The situation of the economically disadvantaged population is even more difficult and the death rate is even higher in this population group. The aim of our study was to study the trends in the mental health of the population of Georgia under the conditions of global climate change. The results of our research show that mental disorders are quite common in Georgia, the morbidity rates are especially high among children and adolescents, which is unfortunate for a country with such a small population as Georgia.

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Seafood is an essential part of nutrient acquisition and is considered a staple food in areas located nearby water bodies. The potential pathogens associated with seafood consumption are often neglected to make foodborne zoonosis more likely to occur. Anisakiasis resulting from infected nematodes Anisakis has worldwide distribution including developing continents like Asia (China, Japan, Korea and Bangladesh) and some developed areas like the Netherlands and the United States. Despite a global burden of morbidities and fatalities, Anisakiasis remains a neglected zoonotic disease. The intensity and distribution of disease rise owing to the consumption of different kinds of raw or improperly cooked seafood like sushi etc. There is no proper treatment for Anisakiasis owing to the delays in reaching out for medical opinions. Keeping in view the gaps in Anisakiasis research and surveillance, we should improve the treatment with medicine, surgery, and essential oil and curtail the transmission of diseases from parasites to humans. There are gaps in the existing information on the epidemiological significance of the so far known species of Anisakis, both in their natural and accidental host-like human population worldwide. This review signifies the importance of awareness, knowledge of Anisakiasis among humans and animals from a global viewpoint. A holistic approach by thorough assessment of the rapidly spreading disease Anisakiasis in natural and accidental hosts as well as in marine ecosystems is required to prevent morbidities and mortalities in humans

Peanut Skins as a Natural Antimicrobial Feed Additive To Reduce the Transmission of Salmonella in Poultry Meat Produced for Human Consumption

Salmonella is the leading cause of bacterial foodborne zoonoses in humans. Thus, the development of strategies to control bacterial pathogens in poultry is essential. Peanut skins, a considerable waste by-product of the peanut industry is discarded and of little economic value. However, peanut skins contain identified polyphenolic compounds that have antimicrobial properties. Hence, we aim to investigate the use of peanut skins as an antibacterial feed additive in the diets of broilers to prevent the proliferation of Salmonella Enteritidis (SE). One hundred sixty male hatchlings (Ross 308) were randomly assigned to (i) peanut skin diet without SE inoculation (PS); (ii) peanut skin diet and SE inoculation (PSSE); (iii) control diet without SE inoculation (CON); and (iv) control diet with SE inoculation (CONSE). Feed intake and body weights were determined at weeks 0 and 5. On days 10 and 24 posthatch, three birds per pen (24 total) from each treatment group were euthanized, and the liver, spleen, small intestine, and ceca were collected. The weights of the liver, spleen, and ceca were recorded. Organ invasion was determined by counting SE colonies. Each pen served as an experimental unit and was analyzed by using a t test. Performance data were analyzed in a completely randomized design by using a general linear mixed model to evaluate differences. There were no significant differences (P > 0.05) in weekly average pen body weight, total feed consumption, bird weight gain, and feed conversion ratio between the treatment groups. There were no significant differences in SE CFU per gram for fecal, litter, or feed between the treatment groups CONSE and PSSE. However, for both fecal and litter, the PSSE treatment group tended (P ≤ 0.1) to have a lower Salmonella CFU per gram compared with the CONSE treatment group. The results indicate that peanut skins may have potential application as an antimicrobial feed additive to reduce the transmission or proliferation of SE in poultry environments or flocks.

Pigs' management practices and exposure to Trichinella spp. in pigs and warthogs in the northern area of Senegal.

Trichinellosis is a neglected and emerging foodborne zoonosis in Africa. Trichinella infection occurs through the consumption of raw or undercooked infected meat and meat products. This study aimed to assess pigs' management practices and determine the exposure of pigs and warthogs to Trichinella spp. in the northern area of Senegal. Surveys and observations were carried out among 40 pig farmers to assess husbandry practices regarding Trichinella spp. life cycle. In addition, 201 pig meat juices and 83 warthog meat juices were extracted and tested for anti-Trichinella antibodies by indirect enzyme-linked immunosorbent assay. Most (97%) of farms practiced a traditional farming system with free-ranging of pigs in 85% of farms. Farms had local pig breed without housing and supplementary feeding. Some farmers (27.5%) used slaughter waste to feed pigs and farmers were not aware that free-range farming is a source of infection to Trichinella infection. They were also unaware that some pig diseases could be transmitted to humans. The seroprevalence of Trichinella infection was 10.9% (95% confidence interval [CI]: 6.6-15.2%) in pigs and 10.8% (95% CI: 4.16-17.52%) in warthogs with significantly higher seroprevalence in male (22.2%: 95% CI: 6.6-37.8%) compared to female (9.2%; 95% CI: 4.9-13.5%) (p < 0.05). The confirmation of exposure to Trichinella spp. in this area in pigs and warthogs shows a significant risk of transmission of this disease to humans if the farming conditions and the health surveillance system are not respected. However, control measures are needed to reduce any risk of transmission of Trichinella infection to humans.

Quantification of Campylobacter contamination on chicken carcasses sold in retail markets in the United Arab Emirates

BackgroundCampylobacter is among the leading causes of foodborne zoonotic disease worldwide, with chicken meat accounting for the majority of human illnesses. This baseline study generates the first quantitative data for Campylobacter contamination in the United Arab Emirates chicken meat. Such data will help inform risk analysis and develop evidence-based food safety management.MethodsFor a year, chilled whole chicken carcasses (n = 315) belonging to seven different companies were collected from retail supermarkets. According to standard methods, Campylobacter enumeration was achieved by a direct plating in all chicken samples, and isolates were confirmed using multiplex PCR.ResultsCampylobacter spp. were recovered from 28.6% (90/315) of the samples. Campylobacter enumeration results indicated that 71.4% of the tested samples were contaminated with < 1 log10 CFU (colony-forming units)/g, and 7% were contaminated with ≥3 log10 CFU/g. The mean Campylobacter concentration was 2.70 log10 CFU/g, with a standard deviation of 0.41 log10 CFU/g. Campylobacter counts varied significantly in relation to the sourcing chicken processing companies. Six out of the seven surveyed companies provided Campylobacter positive samples. Moreover, significantly higher (p-value< 0.0001) counts were found to be associated with smaller size chicken carcasses (weighted 600–700 g; compared to the other categories, 800 g and 900–1000 g). Interestingly, C. coli was present in 83% of the positive samples, while C. jejuni was only detected in 6.4% of the samples. Compared with studies from other countries utilizing the same enumeration method, the UAE chicken appears to have a lower prevalence but a higher Campylobacter count per gram of carcasses. Higher Campylobacter counts were significantly associated with smaller carcasses, and C. coli was the dominant species detected in this study’s samples.ConclusionThese results add to our understanding of the local, regional and global epidemiology of Campylobacter in chicken meat. Outputs of the current study may aid in developing a risk assessment of Campylobacter in the UAE, a country among the biggest per capita consumption markets for chicken meat worldwide.

From the Intersection of Food-Borne Zoonoses and EU Green Policies to an In-Embryo One Health Financial Model.

The European Union (EU) adopts the One Health (OH) approach, based on the relationships between human, animal, and environmental health. OH concerns a multitude of aspects, some of which are discussed here. OH overlaps the European Green Deal plan and its relaunched Farm to Fork Strategy, which aims at spreading organic farms adopting the circular economy, in order to improve human health through both better environmental conditions and healthier food. Nevertheless, zoonoses cause sanitary cost in terms of infected farm personnel, lower productivity, and lower fertility of infected farm animals. In such scenarios, the decreased breeding yield and the lower income induce higher cost of farm products, meaning that the market price rises, becoming uncompetitive when compared to the prices of industrial products. Consequently, lower revenues can hinder the farm growth expected in the framework of the EU Green Deal. Since zoonosis control is a key element in aligning EU policies aimed at achieving the EU Green Deal goal of “ZERO environmental impact” by 2050, the authors suggest the inclusion of the parameter economic health in the OH approach, in order to individuate EU Member States (MSs) economically unable to conduct eradication programmes and to finance them. Economic health is here considered as a starting point of the new ethical and science-based One Health Financial Model that the authors suggest as an in-embryo model, in which specific rules should regulate public funds, private investments, and trading, which should exclusively concern public services and private enterprises complying with most of the OH parameters. In this way, economic losses due to collateral negative effects deriving from human activities can be progressively decreased, and the entire planet will benefit from the process. Despite the considerable efforts being carried out in the context of the OH approach, war causes tragic and devastating effects on the physical and mental health of human beings, on their lives, on pandemic and zoonotic threats, on animals, on plants and, last but not least, on the environment. War is incompatible with OH. Enormous efforts for peace are therefore urgently needed.

Global Prevalence of Echinococcosis in Goats: A Systematic Review and Meta-Analysis.

Echinococcosis is a foodborne parasitic zoonosis caused by the larvae of Echinococcus. This disease can affect goats and other mammals. In this study, a systematic review and meta-analysis for echinococcosis in global goats were performed based on the following five databases (China National Knowledge Infrastructure [CNKI], VIP Chinese Journal Database, Wanfang Data, PubMed, and ScienceDirect). In total, 108,197 samples were collected. The global prevalence of echinococcosis in goats was identified to be 10.85% (3217/108,197). The prevalence of echinococcosis in goats was 6.16% (1369/22,208) and 13.27% (874/5932) in South America and Africa, respectively. The prevalence of echinococcosis in goats before 2010 (9.76%; 112/713) was significantly higher than that from 2010 to 2014 (1.44%; 45/32,145) or after 2014 (2.95%; 154/3889). The prevalence of echinococcosis in goats aged <12 months (4.48%; 70/2911) was higher than that in goats aged ≥12 months (2.88%; 36/819). We also investigated the effects of geographical factors and climates on the prevalence of echinococcosis in goats. The results showed that the prevalence of echinococcosis was higher in the areas with high altitude and cold climate. This meta-analysis indicated that echinococcosis was ubiquitous in goats. Thus, we should improve the feeding conditions for goats, and strengthen the control measures of echinococcosis epidemic in goats, with the aims of reducing the economic losses of animal husbandry and providing protection for humans in the aspects of food security and health.

In vitro evaluation of sodium butyrate on the growth of three Salmonella serovars derived from pigs at a mild acidic pH value.

Foodborne zoonotic diseases can be transferred into the food chain at the stage of livestock farming. As an emerging public health challenge, practicable reduction measures in porcine health management for Salmonella are constantly being investigated. This in vitro study aimed to determine the influence of six different sodium butyrate (SB) concentrations (0, 5, 10, 20, 40, and 80 mM) on the growth of three different Salmonella enterica serovars at a constant pH value of 6.0, corresponding to conditions in the pig's hindgut. S. Derby and S. Typhimurium, isolated from a pig farm, and S. Typhimurium DSM 19587, which served as control, were used. Broth microdilution assay was applied to record Salmonella growth in the presence of different SB-concentrations over six different incubation periods (0, 1, 2, 4, 6, and 24 h). Results were quantified in the log colony-forming units (log10 CFU/mL). For 1 h incubation, the addition of SB showed no significant differences in the range of initial Salmonella dose of about 5.7 log10 between concentrations (0–80 mM, 5.26 ± 0.10–5.60 ± 0.07 log10, p > 0.05). After 6 h, for SB addition, the range of Salmonella counts was significantly lower compared to no addition of SB (5–80 mM, p < 0.05), 6.78 ± 0.84–7.90 ± 0.10 log10 for 5 mM, and 7.53 ± 0.04–8.71 ± 0.22 log10 for 0 mM. Moreover, for SB concentrations of 40 and 80 mM, no difference in the range of Salmonella counts over 6 h was obtained (5.23 ± 0.11–5.38 ± 0.05 log10, p > 0.05), and minor Salmonella growth was recorded at the earliest after 24 h incubation. Growth rates for varying SB concentrations and incubation times were confirmed in a similar manner for the three serovars. Obtained results suggest that increasing SB concentrations suppress Salmonella growth for concentrations of 5–20 mM over a 6 h incubation period and for 40 and 80 mM over a 24 h incubation period. When transferring these in vitro findings to the porcine organism, it may be assumed that Salmonella reduction can be achieved by increased butyrate content in the chyme of the large intestine.

Survival of Campylobacter jejuni Co-Cultured with Salmonella spp. in Aerobic Conditions.

Campylobacter and Salmonella are responsible for the two major foodborne zoonotic diseases in Europe; poultry is the main infection source. Campylobacter cannot grow under aerobic conditions, but can show aerobic survival when co-cultured with other microorganisms; however, its interaction with Salmonella has not been studied yet. In this study, these two bacteria were co-cultured under controlled aerobic conditions. Different concentrations and strains of C. jejuni were incubated with or without different Salmonella serotypes (10 CFU) at 37 °C for 16 h. C. jejuni did not grow after incubation with or without Salmonella. The survival of C. jejuni was observed only for the highest initial concentration of 6 log CFU/mL with or without Salmonella. However, its survival was significantly higher when co-cultured with Salmonella. No survival was observed at lower concentrations. C. jejuni survival was positively affected by the presence of Salmonella but depended on the Salmonella serotype, the C. jejuni strain and the initial concentration. On the other hand, the Salmonella enumerations were not affected by C. jejuni. Our results suggest potential interactions between Salmonella and C. jejuni that require further investigations for a clearer understanding of their behavior in natural habitats.

Isolation and characterization of Yersinia enterocolitica from foods in Apulia and Basilicata regions (Italy) by conventional and modern methods.

Yersiniosis is the third most reported food-borne zoonosis in Europe. The aim of the present study was to perform the search for Yersinia enterocolitica in food samples collected from Apulia and Basilicata regions (Southern Italy) and to characterize any isolates by classical and modern analytical methods. A total of 130 samples were analyzed between July 2018 and July 2019: most of them were raw milk and dairy products made from it. Furthermore, 8 out of 130 samples were individual milk samples collected from bovines reared in a Brucella-free farm which showed false positive serological reaction for brucellosis due to the presence of pathogenic Y. enterocolitica O:9 biotype 2 in faeces. The Real Time PCR targeting the ail gene and the culture method were performed to detect pathogenic Y. enterocolitica. Isolates were subjected to API 20E (Biomerieux) and MALDI-TOF MS (Matrix Assisted Laser Desorption Ionization Time-of-Flight) for species identification. All samples were negative for the ail gene. The culture method allowed to isolate suspicious colonies from 28 samples. The API 20E system and the MALDI-TOF MS technique identified 20 Y. enterocolitica and 1 Y. intermedia in a concordant way. The remaining 7 strains were all identified as Y. enterocolitica by the API 20E system, while the MALDI-TOF MS recognized 4 Y. intermedia, 1 Y. bercovieri and 2 Y. massiliensis. Genotypic characterization of the discordant strains was performed by rMLST and it confirmed the MALDI-TOF MS’ results. Only non-pathogenic Y. enterocolitica biotype 1A strains were found, although with a non-negligible prevalence (P = 0.15 with CI 95% = ± 0.06). This study indicates a poor circulation of pathogenic Y. enterocolitica in food products made and marketed in the investigated areas. However, the small number of samples, insufficient for some food categories such as meat and vegetable, does not allow to exclude the presence of pathogenic strains at all.

Occurrence, antimicrobial resistance, virulence, and biofilm formation capacity of Vibrio spp. and Aeromonas spp. isolated from raw seafood marketed in Bangkok, Thailand.

Background and Aim:Bacteria of the genera Vibrio and Aeromonas cause seafood-borne zoonoses, which may have a significant impact on food safety, economy, and public health worldwide. The presence of drug-resistant and biofilm-forming phenotypes in the food chain increases the risk for consumers. This study aimed to investigate the characteristics, virulence, biofilm production, and dissemination of antimicrobial-resistant pathogens isolated from seafood markets in Bangkok, Thailand.Materials and Methods:A total of 120 retail seafood samples were collected from 10 local markets in Bangkok and peripheral areas. All samples were cultured and the Vibrio and Aeromonas genera were isolated using selective agar and biochemical tests based on standard protocols (ISO 21872-1: 2017). The antibiotic susceptibility test was conducted using the disk diffusion method. The presence of hemolysis and protease production was also investigated. Polymerase chain reaction (PCR) was used to determine the presence of the hlyA gene. Furthermore, biofilm formation was characterized by microtiter plate assay and scanning electron microscopy.Results:The bacterial identification test revealed that 35/57 (61.4%) belonged to the Vibrio genus and 22/57 (38.6%) to the Aeromonas genus. The Kirby–Bauer test demonstrated that 61.4% of the isolates were resistant to at least one antibiotic and 45.61% had a high multiple antibiotic resistance index (≥0.2). PCR analysis indicated that 75.44% of the bacteria harbored the hlyA gene. Among them, 63.16% exhibited the hemolysis phenotype and 8.77% showed protease activity. The biofilm formation assay demonstrated that approximately 56.14% of all the isolates had the potential to produce biofilms. The moderate biofilm production was the predominant phenotype.Conclusion:The results of this study provide evidence of the multiple drug resistance phenotype and biofilm formation capacity of Vibrio and Aeromonas species contaminating raw seafood. Effective control measures and active surveillance of foodborne zoonoses are crucial for food safety and to decrease the occurrence of diseases associated with seafood consumption.

Prevalence of Listeria monocytogenes in Foods of Animal Origin: Study from Assam, A North-Eastern State of India

Listeriosis is an important emerging bacterial food-borne zoonotic disease caused by Listeria monocytogenes. During the last two decades, the organism has been implicated in several food-borne disease outbreaks making it a serious public health hazard. The pathogenic strains of Listeria can cause severe illness in man after the ingestion of contaminated food products, especially the refrigerated foods of animal origin. In India, very few studies have been carried out in respect to the occurrence and incidence of L. monocytogenes. Assam, one of the eight states of Northeastern India, where approximately 79.0 percent of the total population are non-vegetarians. Chicken meat, pork, chevon and beef are exclusively taken as regular food items throughout the state. The present study describes about isolation, identification and molecular characterization of L.monocytogens from different foods of animal origin from Assam, India. A total of 750 different meat (chicken, chevon, pork and beef) and milk and their products (curd and paneer) samples were collected and analyzed for presence of Listeria. Isolation of L. monocytogenes was done from different food samples of animal origin by using selective enrichment method. PCR was employed for confirmation of the suspected cultures of Listeria targeting prsand16SrRNAgene. Upon confirmation, the isolates were further characterized based on 16S rRNA gene and phylogenetic analysis was performed. Of 750 samples, 48 (6.4%) samples were found positive. The highest rate of isolation of Listeria spp. was recorded in raw milk (8.95%) followed by curd (6.58%), chevon (5.36%), chicken (5.74%), pork (5.98%) and beef (3.75%). Molecular characterization of the isolates based on 16S rRNA gene of L.monocytogens isolated from foods of animal origin from Assam with that of other sequences reported from different parts of the world revealed that all the isolates of the present study are clustered along with other L.monocytogens isolates reported from different parts of the world, however, showing more closely related to isolates reported from China.

Isolation of 15 hepatitis E virus strains lacking ORF1 rearrangements from wild boar and pig organ samples and efficient replication in cell culture.

As a zoonotic pathogen, the hepatitis E virus (HEV) leads to numerous infections in humans with different clinical manifestations. Especially genotype 3, as causative agent of a foodborne zoonosis, is transmitted to humans by ingestion of undercooked or raw meat containing liver from HEV-infected animals. Although the virus' prevalence and dissemination in hosts like wild boar and pig have been well characterized, HEV is greatly understudied on a molecular level and reliable cell culture models are lacking. For this reason, the present study concentrated on the isolation and subsequent characterization of porcine HEV from tissue samples derived from wild boar and domestic pigs: 222 wild boars hunted in Northern Germany were investigated for the presence of HEV RNA with a detection rate of 5.9%. Three additional HEV-positive wild boar liver samples as well as an HEV-positive spleen and a positive kidney from domestic pigs were included. After inoculation of positive samples onto the human hepatoma cell line PLC/PRF/5, cells were grown for several weeks. Successful isolation was confirmed by RT-qPCR, virus passage, immunofluorescence staining and titration. Overall, 15 strains from a total of 18 RNA-positive organ samples could be obtained and viral loads>109 RNA copies/ml were measured in cell culture supernatants. Accordingly, 83.3% of the HEV RNA-positive samples contained infectious hepatitis E viral particles and therefore must be considered as a potential source for human infections. Phylogenetic analyses revealed that all isolated strains belong to genotype 3. Further genetic characterization showed a high degree of sequence variability, but no sequence insertions, in the hypervariable region within the open reading frame 1.