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Yersinia pestis: still a plague in the 21st century.

Yersinia pestis, the causative agent of plague, is an aerobic, non-motile, gram-negative bacillus belonging to the family Enterobacteriacea. It is a zoonotic infection transmitted to humans via the bite of a flea. Three clinical forms of human plague exist: bubonic, pneumonic, and septicemic. Many important virulence factors associated with this organism are responsible for its extreme pathogenicity and high mortality rates. The bubonic form of plague is usually not transmitted human to human but the pneumonic form is--through inhalation of contaminated aerosol droplets. The pneumonic plague would be the form most likely implicated in the event of an intentional attack. Inhalation of aerosols can cause devastating consequences resulting in many casualties. Unless antibiotics are administered within 24 hours of the initial symptoms, death is inevitable. Its potential for use as a biological weapon is of major concern to public health officials.

Anti-Bacterial Agents↗

Do dogs and cats present a risk of transmission of salmonellosis to humans?

Examination of rectal swabs from 187 dogs and 13 cats showed that Salmonella spp. was present in only one dog, a 4-month old mongrel puppy, weighing 3.5 kg. It was identified as S. dublin, a species specific serovar of cattle. The animal exhibited no signs of disease during clinical examination. Of the total number of examined animals this positive dog represents only 0.5%. Within the group of patients included in our monitoring in none of those with gastrointestinal problems it was possible to isolate Salmonella spp. This indicates that the risk of transmission of salmonellosis from dogs and cats in the region of Kosice seems to be rather low. On the basis of literature and our own observations we identified the potential sources and the possible ways of the transfer of this disease. The most common appears to be the oral infection by infected feed of various types, particularly by direct contamination of feed with either animal or human contaminants. In dogs and cats salmonellosis occurs most frequently in a latent form. The clinical findings vary with regard to the number of pathogens, immune status of the host, occurrence of health complications and the form of associated disease units. There are suitable isolation and diagnostic methods for diagnostics of salmonellosis. Due to the need for continuous protection of health of humans and animals, screening of occurrence of zoonotic pathogens appears topical. (Tab. 3, Fig. 1, Ref. 35.).

Animals↗

Cultivation of Babesia and Babesia-like blood parasites: agents of an emerging zoonotic disease.

Babesia and its close relatives are members of a group of organisms called piroplasms, a name which comes from their pear-shaped outlines. Long associated with blood diseases of cattle and other mammals, members of the genus Babesia have been recognized since the 1950s as infectious agents in humans. Species of this protozoan blood parasite that have routinely been isolated from mice (B. microti) or cattle (B. divergens) have also been isolated from humans. In addition to these familiar species, new isolates that resist being placed in existing taxonomic categories are the basis for rethinking their phylogenetic relationships based on sequencing data. The parasite represents a threat to the safety of the blood supply in that blood from asymptomatic humans can transmit Babesia to blood recipients. Such transmissions have occurred. The development of methods for cultivation of these organisms represents a significant opportunity to study their biology and disease potential. In addition, in vitro cultivation has provided a basis for studying immune responses of mammals to these infectious agents, with the hope of ultimately producing attenuated strains that could be used for immunizing of cattle and, perhaps, humans who live in areas of endemicity. The microaerophilous stationary phase culture technique, which uses a tissue culture medium base supplemented with appropriate serum and erythrocytes, has made it possible to obtain large numbers of parasitized erythrocytes for studying the biology of this parasite.

Animals↗

The food safety perspective of antibiotic resistance.

Bacterial antimicrobial resistance in both the medical and agricultural fields has become a serious problem worldwide. Antibiotic resistant strains of bacteria are an increasing threat to animal and human health, with resistance mechanisms having been identified and described for all known antimicrobials currently available for clinical use. There is currently increased public and scientific interest regarding the administration of therapeutic and sub-therapeutic antimicrobials to animals, due primarily to the emergence and dissemination of multiple antibiotic resistant zoonotic bacterial pathogens. This issue has been the subject of heated debates for many years, however, there is still no complete consensus on the significance of antimicrobial use in animals, or resistance in bacterial isolates from animals, on the development and dissemination of antibiotic resistance among human bacterial pathogens. In fact, the debate regarding antimicrobial use in animals and subsequent human health implications has been going on for over 30 years, beginning with the release of the Swann report in the United Kingdom. The latest report released by the National Research Council (1998) confirmed that there were substantial information gaps that contribute to the difficulty of assessing potential detrimental effects of antimicrobials in food animals on human health. Regardless of the controversy, bacterial pathogens of animal and human origin are becoming increasingly resistant to most frontline antimicrobials, including expanded-spectrum cephalosporins, aminoglycosides, and even fluoroquinolones. The lion's share of these antimicrobial resistant phenotypes is gained from extra-chromosomal genes that may impart resistance to an entire antimicrobial class. In recent years, a number of these resistance genes have been associated with large, transferable, extra-chromosomal DNA elements, called plasmids, on which may be other DNA mobile elements, such as transposons and integrons. These DNA mobile elements have been shown to transmit genetic determinants for several different antimicrobial resistance mechanisms and may account for the rapid dissemination of resistance genes among different bacteria. The increasing incidence of antimicrobial resistant bacterial pathogens has severe implications for the future treatment and prevention of infectious diseases in both animals and humans. Although much scientific information is available on this subject, many aspects of the development of antimicrobial resistance still remain uncertain. The emergence and dissemination of bacterial antimicrobial resistance is the result of numerous complex interactions among antimicrobials, microorganisms, and the surrounding environments. Although research has linked the use of antibiotics in agriculture to the emergence of antibiotic-resistant foodborne pathogens, debate still continues whether this role is significant enough to merit further regulation or restriction.

Animal Husbandry↗

Copper is an intestinal habitat filter affecting the gut microbiota interactions with Salmonella Typhimurium.

BACKGROUND: Foodborne pathogens, including Salmonella enterica serovar Typhimurium (S. Typhimurium), pose a significant threat to both human health and livestock productivity. The pandemic S. Typhimurium ST34 clone acquired a genomic island (SGI-4) conferring high copper resistance, an adaptation relevant in the context of the widespread use of copper sulphate at therapeutic levels in pig farming. We investigated how high dietary copper influences the piglet gut microbiota and Salmonella-microbiota interactions that may explain the global spread of S. Typhimurium ST34. RESULTS: An on-farm study combined with faecal shotgun metagenomics revealed that several potential Salmonella competitor species, including Bifidobacterium, Escherichia, and Lactobacillus, were less abundant in piglets on high-copper diets. Anaerobic and aerobic culturing alongside whole genome sequencing of 131 species and copper sulphate susceptibility testing identified copper resistance gene acquisition in selected microbes, particularly within Escherichia. Niche competition assays demonstrated that copper resistance is critical for inter-species competition under high-copper conditions, with Salmonella's Type VI Secretion System providing a distinct advantage over Escherichia in the copper-modified niche. CONCLUSIONS: Our findings suggest that copper supplementation alters the piglet gut environment, impacting competitive dynamics between pathogenic and commensal bacteria, likely to influence the zoonotic transmission of pathogens. Video Abstract.

Animals↗

Oral vaccine that breaks the transmission cycle of the Lyme disease spirochete can be delivered via bait.

Borrelia burgdorferi causes Lyme disease, a potentially debilitating human disease for which no vaccine is currently available. We developed an oral bait delivery system for an anti-B. burgdorferi vaccine based in OspA. Mice were immunized orally via gavage and bait feeding. Challenge was performed via Ixodes scapularis field nymphs carrying multiple B. burgdorferi strains. Vaccination protected 89% of the mice and the systemic immune response was skewed toward IgG2a/2b production. Moreover, this oral vaccine reduced the pathogen in the tick vector by eight-fold. We conclude that this oral vaccine induces a protective systemic immune response against a variety of infectious B. burgdorferi strains found in nature and therefore it can eliminate this zoonotic pathogen from its major host reservoirs. Because we observed elimination of the spirochete from the tick vector, a broad delivery of this oral vaccine to wildlife reservoirs is likely to disrupt the transmission cycle of this pathogen.

Administration, Oral↗

Canine faecal contamination and parasitic risk in the city of Naples (southern Italy).

BACKGROUND: Dogs are associated with more than 60 zoonotic diseases among which, parasitosis and, in particular, helminthosis, can pose serious public-health concerns worldwide. Many canine gastrointestinal parasites eliminate their dispersion elements (eggs, larvae, oocysts) by the faecal route. The quantity of canine faeces deposited on public and private property in cities worldwide is both a perennial nuisance and an important health issue. Public sites such as playgrounds, parks, gardens, public squares and sandpits may be an important source of human infection. The aim of this study was to evaluate the extent of both canine faecal contamination in the city of Naples (southern Italy), and presence of canine parasitic elements, with particular regard to those which are potential agents of zoonosis. A regular grid of sub-areas (1 km x 700 m) was overlaid on the city map using a Geographical Information System (GIS). In each sub-area the straightest 1 km transect was drawn and digitalized on-screen in the GIS. Between February and May 2005 canine faeces were counted along the 1 km transects in 143 sub-areas, and 415 canine faecal samples were collected and submitted to coprological examinations. Negative binomial regression models and Gaussian random effects models were used to analyze the association between faeces count and human population density taking into account for extraPoisson variability. Logistic regression model was used to evaluate the association between positivity to parasitic elements and number of canine faeces. RESULTS: Out of the 143 studied sub-areas, 141 (98.6%) contained canine faeces. There was a strong spatial gradient with 48% of the total variability accounted by between neighbourhood variability; a positive association between the number of faeces and the human population density was found. Seventy (over 415, 16.9%) canine faecal samples were positive for parasitic elements. There was no association between positivity to parasitic elements and the number of canine faeces. Eggs of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Trichuris vulpis were found, as well as oocysts of Isospora canis. CONCLUSION: In conclusion, the results of the present study, conducted using GIS both for planning and sampling and for evaluation and presentation of findings, showed the presence of canine faecal contamination in the city of Naples, and the presence of canine parasitic elements, some of which are potential agents of zoonosis.

Animals↗

Cryptosporidiosis in Poland: clinical, epidemiologic and parasitologic aspects.

Stool samples from 692 children hospitalized with symptoms of gastroenteritis, were examined for Cryptosporidium parvum. The oocysts were found in 17 (2.4%) children. There was no association with age, sex or location of household. However, relatively higher rate of oocyst exclusion was found among 2-month- to 3-year-old groups (50%) and among children from villages (43%). Six children from the group of infected were additionally screened for general immunocompetence. Four of these exhibited signs of immunodepletion of IgA isotype in serum. This study has established that cryptosporidiosis occurred rather sporadically among children in the examined groups. Further study was undertaken to provide relevant information whether wild small mammals are a zoonotic reservoir of Cryptosporidium sp. Samples were collected from autumn 1989 until spring 1991 in northern Poland, District Mazury Lake. Twenty percent (66 of 330) of the examined mammals were naturally infected with Cryptosporidium sp.: 55 of 275 Clethrionomys glareolus, 6 of 39 Apodemus flavicollis, and 5 of 16 Sorex araneus were positive. The histological study clearly indicates that the population of C. glareolus was infected with C. parvum. Endogenous stages were found in duodenum near the pylorus. The intensity of infection in those animals was generally low, and relatively small numbers of trophozoites and oocysts were found. This report indicates that C. glareolus and possibly other rodents have the potential to act as reservoirs for C. parvum.

Adolescent↗

Prevalences of zoonotic bacteria among seabirds in rehabilitation centers along the Pacific Coast of California and Washington, USA.

Many seabirds are rehabilitated annually by wildlife rehabilitation centers along the Pacific Coast, USA. Although various strains of zoonotic bacteria have been isolated from seabirds, risks to rehabilitators at these centers have not been well documented. From November 2001 through January 2003, we determined the prevalence of detectable enteric fauna by isolation and characterization of Gram-negative bacteria from cloacal swabs taken from 26 common murres (Uria aalge), 49 gulls (Larus spp.), and 14 other seabirds treated by rehabilitators in California and Washington (USA). At least 25 bacterial species were identified, including multiple strains of Escherichia coli, as well as Enterobacter cloacae, Citrobacter freundii, and Klebsiella pneumoniae. Antibiotic resistance was found in 13 of 19 bacterial isolates tested, including E. coli, K. pneumoniae, Acinetobacter baumanii, and Pseudomonas aeruginosa. Potential transfer of these bacteria poses a risk to wildlife rehabilitators and to seabirds in these centers, as well as to free-ranging birds.

Animals↗

The control of human (neuro)cysticercosis: which way forward?

Taenia solium cysticercosis, and its public health and economic consequences, appears to be a growing problem in poor areas of Africa, Asia and Latin America where people eat pork and traditional pig husbandry is practiced (and expanding). Its burden is counted in terms of human disease (mainly neurocysticercosis related epilepsy) and economic losses, in a context of both commercial and traditional subsistence pig farming. Although substantial fragmentary information seems to be available from local settings, national and global burdens due to T. solium cysticercosis are still to be comprehensively assessed. With regard to control, several strategies have been checked out at a small or medium scale and have proven to be successful. Yet, no intervention programmes have been implemented so far at the national level with proven success. Although T. solium cysticercosis is considered to be a potentially eradicable disease, there is no evidence yet that it is feasible and recommendable to envisage this within a reasonable time frame. However, it appears realistic to aim for the rapid definition of a simple package of interventions, which can routinely be carried out by existing services and structures, and will give an optimal, long-term return in terms of burden relief. Also, a number of international initiatives and opportunities currently exist in which a more pro-active attitude towards the control of T. solium cysticercosis can be integrated and promoted. Commitment of both national and local authorities to control the disease needs to be convincingly solicited and, as for most zoonotic diseases, an interdisciplinary approach is essential.

Animal Husbandry↗

Interaction between probiotic lactic acid bacteria and canine enteric pathogens: a risk factor for intestinal Enterococcus faecium colonization?

Selected probiotic lactic acid bacteria (LAB) have been shown to elicit positive health effects particularly in humans. Competitive exclusion of pathogens is one of the most important beneficial health claims of probiotic bacteria. The effect of probiotic LAB on competitive exclusion of pathogens has been demonstrated in humans, chicken and pigs. In this study we evaluated the ability of certain LAB strains (Lactobacillus rhamnosus GG, Bifidobacterium lactis Bb12, Lactobacillus pentosus UK1A, L. pentosus SK2A, Enterococcus faecium M74 and E. faecium SF273) to inhibit the adhesion of selected canine and zoonotic pathogens (Staphylococcus intermedius, Salmonella Typhimurium ATCC 14028, Clostridium perfringens and Campylobacter jejuni) to immobilised mucus isolated from canine jejunal chyme in vitro. Adhesion of C. perfringens was reduced significantly by all tested LAB strains, between 53.7 and 79.1% of the control without LAB, the LAB of canine origin yielding the best reduction. The adhesion of S. Typhimurium and S. intermedius were not significantly altered by any of the LAB included in the study. Both enterococci tested significantly enhanced the adhesion of C. jejuni, to 134.6 and 205.5% of the control without LAB. E. faecium may thus favor the adhesion and colonization of C. jejuni in the dog's intestine, making it a potential carrier and possibly a source for human infection. Enhanced C. jejuni adhesion is a new potential risk factor of enterococci. Our results further emphasize the importance of safety guidelines to be established for the probiotics intended for animal use.

Animals↗

Neuropathogenesis of herpesvirus papio 2 in mice parallels infection with Cercopithecine herpesvirus 1 (B virus) in humans.

Cercopithecine herpesvirus 1 (monkey B virus; BV) produces extremely severe and usually fatal infections when transmitted from macaque monkeys to humans. Cercopithecine herpesvirus 16 (herpesvirus papio 2; HVP2) is very closely related to BV, yet cases of human HVP2 infection are unknown. However, following intramuscular inoculation of mice, HVP2 rapidly invades the peripheral nervous system and ascends the central nervous system (CNS) resulting in death, very much like human BV infections. In this study, the neurovirulence of HVP2 in mice was further evaluated as a potential model system for human BV infections. HVP2 was consistently neurovirulent when administered by epidermal scarification, intracranial inoculation and an eye splash. Quantitative real-time PCR, histopathology and immunohistochemistry were used to follow the temporal spread of virus following skin scarification and to compare the pathogenesis of neurovirulent and apathogenic isolates of HVP2. Apathogenic isolates were found to be capable of reaching the CNS but were extremely inefficient at replicating within the CNS. It is concluded that neurovirulent strains of HVP2 exhibit a pathogenesis in mice that parallels that observed in human BV infections and that this model system may prove useful in dissecting the viral determinants underlying the extreme severity of zoonotic BV infections.

Animals↗

Use of mobile genetic elements as tools for molecular epidemiology.

Trypanosomiasis is a complex zoonotic disease where human-infective and non-human-infective strains of Trypanosoma brucei interact in the same transmission cycles. Differentiating these strains is paramount to understanding disease epidemiology. Restriction fragment length polymorphism analysis of repetitive DNA has provided such a method for distinguishing human and non-human isolates. Unfortunately, this approach requires large amounts of material and a more rapid approach is required. We have developed a novel technique, mobile genetic element-PCR, for assaying for positional variation of the mobile genetic element, RIME. The trypanosome genome contains up to 400 copies of RIME. Using this approach we have observed considerable variation between strains of T. brucei. Such a technique may offer potential as a method for differentiating non-human- and human-infective trypanosomes and shows promise as a rapid sensitive tool for investigating the epidemiology of sleeping sickness.

Animals↗

Bottle feeding and exposure to Toxocara as risk factors for wheezing illness among under-five Amazonian children: a population-based cross-sectional study.

We investigated the prevalence and risk factors for wheezing and asthma in young Amazonian children. A population-based cross-sectional survey of 606 children aged 6-59 months was performed in two small towns in Acre State, Northwestern Brazil. Information on outcome variables (recent wheezing and medical diagnosis of asthma) and demographic, socioeconomic, environmental, maternal and nutritional variables was obtained by interviewing children's mothers or guardians. Infections with intestinal parasites and antibodies to the zoonotic nematode Toxocara were diagnosed using standard laboratory techniques. Multiple unconditional logistic regression models were used to describe associations between independent variables and outcomes. The prevalence of recent wheezing (one or more reported episodes in the past 12 months) was 42.6%, but only 19.8% of wheezing children were also reported to have a medical diagnosis of asthma (prevalence, 8.5%); 21.5% of the children examined had antibodies to Toxocara. Increased risk of asthma was independently associated with early introduction of bottle feeding, defined as <4 months of exclusive breastfeeding [adjusted odds ratio (aOR) = 2.21, 95% confidence interval (95% CI), 1.07-4.59, P = 0.033], and seropositivity to Toxocara (aOR = 2.37, 95% CI 1.17-4.77, P = 0.016), suggesting two potential targets for public health interventions.

Animals↗

Rabies.

The practicing veterinarian has a key role to play in rabies control in the maintenance of protection in the companion animal populations, in the education of the pet-owning community on rabies, and in the decision-making process that accompanies human exposure to potentially rabid animals. This role encompasses far more than the routine maintenance of health and well-being in pet animal populations. Although it is important to remain diligent in the immunization of domestic pets against rabies to provide a barrier between wildlife, the main reservoir of infection, and man, it is also important to be aware of the current trends in wildlife rabies within a region. Research is currently underway to investigate methods of immunizing wildlife populations, but the effective and widespread control of rabies in these species is still a long way off; in the meantime, there will be an increasing demand for practicing veterinarians to take the lead in the control of this most fearful zoonotic disease.

Animals↗

[Research on three parasitic infestations in rats captured in Marseille: evaluation of the zoonotic risk].

A cross sectional survey was carried out on a population of 82 rats (Rattus norvegicus and Rattus rattus alexandrinus) trapped in Marseille. The main histopathological finding was the presence of adults or eggs of Capillaria hepatica in 44% of the animals. 21% were found with fleas (Xenopsylla cheopis). There was no evidence of trichinosis in any of the rats examined. Hepatic capillariasis is a zoonosis seldom described in human beings. About 30 human cases have been reported in the world. Human infestation occurs first by consumption of raw rat liver containing un-embryonated eggs causing only pseudoparasitism without disease. The genuine mode of infestation is the consumption of sullied soil with rats feces containing embryonated eggs. Therefore parasites provoke, true as in rat inflammatory lesions, necrosis and fibrosis of the liver. The treatment associates antiparasitic drugs such as ivermectine, disophenol or pyrantel tartrate. The presence of a large population of infested synanthropic rats requires epidemiological monitoring and extermination of rats. All physicians must be informed of this potential risk.

Animals↗

Selection of and recombination between minor variants lead to the adaptation of an avian coronavirus to primate cells.

An interesting question posed by the current evidence that severe acute respiratory syndrome coronavirus may be originated from an animal coronavirus is how such an animal coronavirus breaks the host species barrier and becomes zoonotic. In this report, we study the chronological order of genotypic changes in the spike protein of avian coronavirus infectious bronchitis virus (IBV) during its adaptation to a primate cell line. Adaptation of the Beaudette strain of IBV from chicken embryo to Vero cells showed the accumulation of 49 amino acid mutations. Among them, 26 (53.06%) substitutions were located in the S protein. Sequencing analysis and comparison of the S gene demonstrated that the majority of the mutations were accumulated and fixed at passage 7 on Vero cells and minor variants were isolated in several passages. Evidence present suggests that the dominant Vero cell-adapted IBV strain may be derived from the chicken embryo passages by selection of and potential recombination between the minor variants. This may explain why adaptation is a rapid process and the dominant strain, once adapted to a new host cell, becomes relatively stable.

Adaptation, Physiological↗

Cysticercosis/taeniasis in Asia and the Pacific.

Three taeniid tapeworms infect humans in Asia and the Pacific: Taenia solim, Taenia saginata, and Taenia asiatica. Although there is continuing debate about the definition of a new species, phylogenetic analyses of these parasites have provided multiple lines of evidence that T. asiatica is an independent species and the sister species of T. saginata. Here we review briefly the morphology, pathology, molecular biology, distribution and control options of taeniasis/cysticercosis in Asia and the Pacific and comment on the potential role which dogs may play in the transmission of T. solium. Special attention is focused on Indonesia: taeniasis caused by T. asiatica in North Sumatra, taeniasis/cysticercosis of T. solium and taeniasis of T. saginata in Bali, and taeniasis/cysticercosis of T. solium in Papua (formerly Irian Jaya). Issues relating to the spread of taeniasis/cysticercosis caused by T. solium in Papua New Guinea are highlighted, since serological evidence suggests that cysticercosis occurs among the local residents. The use of modern techniques for detection of taeniasis in humans and cysticercosis in humans, pigs and dogs, with the possible adoption of new control measures will provide a better understanding of the epidemiology of taeniasis/cysticercosis in Asia and the Pacific and lead to improved control of zoonotic and simultaneously meat-borne disease transmission.

Animals↗