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[Emergence and species barriers].

Emergent viral infections are defined as those the incidence of which has increased over the last 20 years. These infections concern human but also animal viruses affecting wild or tame animals. In humans, emergent viruses are of zoonotic origin and often due to crossing of species barrier. This inter-species crossing is promoted by various circumstances: environmental and climatic variations, bioterrorism, evolutive potential of the virus, etc. Screening for the animal reservoir is extremely important to prevent re-emergence and to eradicate the disease. The emergential success of some viruses has had serious consequences on human public health: flu pandemics, AIDS pandemic, hemorrhagic fever, and more recently SARS.

Animals↗

Diversity of serotypes of Campylobacter jejuni and Campylobacter coli isolated in laboratory animals.

One hundred nineteen isolates of Campylobacter jejuni and Campylobacter coli from nine laboratory animal species were serotyped using antisera to 20 Penner serotypes commonly isolated from cases of human enteric infections. Although C. jejuni and C. coli were isolated from laboratory animals with diarrhea, the majority were cultured from asymptomatic animals (81%). Seven of twenty-two isolates from animals with diarrhea were serotype 4 (32%) and three were serotype 1 (14%). Sixty-one of the 119 isolates (51%) were typeable using the 20 Penner antisera indicating that many of the isolates obtained from 29 nonhuman primates (five species), 20 ferrets, 7 hamsters, 15 cats and 48 dogs are serotypes commonly associated with human enteritis. Among typeable strains, 13 different serotypes were identified. Two particular serotypes, 4 and 19 were isolated from several species of animals and comprised 24% of the isolates studied. Since asymptomatic laboratory animals of several different species harbor serotypes of C. jejuni and C. coli that are potentially pathogenic to man, appropriate precautions should be instituted to minimize exposure of personnel to the organisms in laboratory animal feces. If suspected cases of zoonotic-related enteric campylobacteriosis involving laboratory animals do occur, serotyping of isolates would be a useful epidemiologic marker in studying the outbreak.

Animals↗

Human infection with foamy viruses.

Virtually all nonhuman primate species investigated thus far including prosimians, New World and Old World monkeys and apes all harbor distinct and species-specific clades of simian foamy virus (SFV). However, evidence supporting the existence of a human-specific foamy virus (FV) is not yet available. Early reports describing widespread infection of healthy and sick humans with FV could not be confirmed. In contrast, all FV infections documented in humans are of zoonotic origin and are identified in persons occupationally exposed to nonhuman primates. The introduction of SFV into humans raises several public health questions regarding disease outcomes and potential for human-to-human transmissibility. The available data from a very limited number of SFV-infected humans suggest that these infections are nonpathogenic and are not easily transmissible. Additional studies are needed to better define the prevalence and natural history of SFV in humans.

Animals↗

[SARS, possible zoonosis in the area of conflict of pathogenic coronaviruses of animals].

Severe acute respiratory syndrome (SARS) is an emerging disease, which was first recognized in Guangdong Province, China, in November 2002. In the meantime, SARS has been recognized in patients on all five continents. A novel coronavirus, which is not related to the hitherto known coronaviruses, has been proven to be associated with the disease. Our genomic analyses strongly suggest that the new SARS-coronavirus did not emerge through mutation or recombination and that it has probably been transmitted from a so far not identified animal species to humans. Therefore, it is most likely that SARS virus is a zoonotic agent. A broad body of knowledge originating from research in veterinary medicine indicates that development of vaccines against the SARS-coronavirus may be problematic. The potential danger of such vaccines should not be neglected during the process of vaccine development.

Animals↗

Incidence and control of Campylobacter in foods.

Campylobacter jejuni is known as the most common human enteropathogen in developed countries. The epidemiology of the organism has now been adequately determined and indicates that campylobacteriosis is a zoonotic disease. Pets, water, and contaminated foods are the main sources of sporadic infections in humans, and no single animal food source can be excluded as a potential vehicle for infection of humans. The available information indicates that 50 to 70% of cases of enteritis in man are associated with poultry. Cross-contamination and improper handling and cooking of foods of animal origin account for the majority of disease. Hygienic measures must be applied in order to reduce the incidence of campylobacteriosis in humans.

Adolescent↗

Rotavirus an emerging enteropathogen of man and animals: an overview.

Rota Viral infection is recognised as a significant global public health concern causing large numbers of potentially preventable illnesses and deaths, especially among young ones of man and animals. The paper presents an overview of the epidemiology, control, treatment, virology, diagnosis and the zoonotic aspects of the problem. Problems for further research are identified.

Animals↗

Transmission of infectious diseases during commercial air travel.

Because of the increasing ease and affordability of air travel and mobility of people, airborne, food-borne, vector-borne, and zoonotic infectious diseases transmitted during commercial air travel are an important public health issue. Heightened fear of bioterrorism agents has caused health officials to re-examine the potential of these agents to be spread by air travel. The severe acute respiratory syndrome outbreak of 2002 showed how air travel can have an important role in the rapid spread of newly emerging infections and could potentially even start pandemics. In addition to the flight crew, public health officials and health care professionals have an important role in the management of infectious diseases transmitted on airlines and should be familiar with guidelines provided by local and international authorities.

Aerospace Medicine↗

Cryptosporidiosis. A global challenge.

During the last 30 years, our concept of cryptosporidiosis has changed from that of a rare, largely asymptomatic disease, to an important cause of diarrhea in animals and humans worldwide. Significant disease first appeared in cattle. Subsequently, the zoonotic danger of the organism was recognized in HIV-infected persons and young children. Cryptosporidium are now ubiquitous and disease has been described in over 79 host species. Cryptosporidiosis has become a major cause of calfhood diarrhea worldwide. In humans it accounts for up to 20% of all cases of childhood diarrhea in developing countries and is a potentially fatal complication of AIDS. Waterborne contamination is a growing concern as a source of widespread outbreaks of disease. Factors that have contributed to the emergence of cryptosporidiosis in animals include biological features of the organism, the lack of an effective treatment or preventative, increased environmental contamination, and trends in livestock production. In humans the zoonotic nature of infection and an increased at-risk population have contributed to disease. Genetic characterization of Cryptosporidium, improved detection methods, and a better understanding of the factors that predispose to disease are important contributions to understanding the epidemiology of cryptosporidiosis.

AIDS-Related Opportunistic Infections↗

Assessment of the viral safety of antivenoms fractionated from equine plasma.

Antivenoms are preparations of intact or fragmented (F(ab')2 or Fab) immunoglobulin G (IgG) used in human medicine to treat the severe envenomings resulting from the bites and stings of various animals, such as snakes, spiders, scorpions, or marine animals, or from the contact with poisonous plants. They are obtained by fractionating plasma collected from immunized horses or, less frequently, sheep. Manufacturing processes usually include pepsin digestion at acid pH, papain digestion, ammonium sulphate precipitation, caprylic acid precipitation, heat coagulation and/or chromatography. Most production processes do not have deliberately introduced viral inactivation or removal treatments, but antivenoms have never been found to transmit viruses to humans. Nevertheless, the recent examples of zoonotic diseases highlight the need to perform a careful assessment of the viral safety of antivenoms. This paper reviews the characteristics of equine viruses of antivenoms and discusses the potential of some manufacturing steps to avoid risks of viral contamination. Analysis of production parameters indicate that acid pH treatments and caprylic acid precipitations, which have been validated for the manufacture of some human IgG products, appear to provide the best potential for viral inactivation of antivenoms. As many manufacturers of antivenoms located in developing countries lack the resources to conduct formal viral validation studies, it is hoped that this review will help in the scientific understanding of the viral safety factors of antivenoms, in the controlled implementation of the manufacturing steps with expected impact on viral safety, and in the overall reinforcement of good manufacturing practices of these essential therapeutic products.

Animals↗

Venezuelan encephalitis emergence mediated by a phylogenetically predicted viral mutation.

RNA viruses are notorious for their genetic plasticity and propensity to exploit new host-range opportunities, which can lead to the emergence of human disease epidemics such as severe acute respiratory syndrome, AIDS, dengue, and influenza. However, the mechanisms of host-range change involved in most of these viral emergences, particularly the genetic mechanisms of adaptation to new hosts, remain poorly understood. We studied the emergence of Venezuelan equine encephalitis virus (VEEV), an alphavirus pathogen of people and equines that has had severe health and economic effects in the Americas since the early 20th century. Between epidemics, VEE disappears for periods up to decades, and the viral source of outbreaks has remained enigmatic. Combined with phylogenetic analyses to predict mutations associated with a 1992-1993 epidemic, we used reverse genetic studies to identify an envelope glycoprotein gene mutation that mediated emergence. This mutation allowed an enzootic, equine-avirulent VEEV strain, which circulates among rodents in nearby forests to adapt for equine amplification. RNA viruses including alphaviruses exhibit high mutation frequencies. Therefore, ecological and epidemiological factors probably constrain the frequency of VEE epidemics more than the generation, via mutation, of amplification-competent (high equine viremia) virus strains. These results underscore the ability of RNA viruses to alter their host range, virulence, and epidemic potential via minor genetic changes. VEE also demonstrates the unpredictable risks to human health of anthropogenic changes such as the introduction of equines and humans into habitats that harbor zoonotic RNA viruses.

Amino Acids↗

[Importance of the different species and genotypes of Cryptosporidium in public health].

Until recently, only the bovine and human genotypes of Cryptosporidium parvum had been considered to infect man and to be potential pathogens. Lately, symptomatic infections with C. felis, C. meleagridis, and C. parvum-like dog genotype have been described in immunocompetent and immunosuppressed individuals. These findings suggest that zoonotic parasites could also play an important role in Public Health.

Animals↗

[Importance of the different species and genotypes of Cryptosporidium in public health].

Until recently, only the bovine and human genotypes of Cryptosporidium parvum had been considered to infect man and to be potential pathogens. Lately, symptomatic infections with C. felis, C. meleagridis, and dog C. parvum-like genotype have been described in immunocompetent and immunosuppressed individuals. These findings suggest that zoonotic parasites could also play an important role in Public Health.

Animals↗

Cryptosporidiosis: a brief literature review and update regarding Cryptosporidium in feces of Canada geese (Branta canadensis).

Canada geese are increasingly abundant in Ohio, with large nesting populations throughout the state, and goose feces contaminate grassy areas and pavements in many public, commercial, and residential sites. In 1999 the authors found a high prevalence of Giardia, Campylobacter, and especially Cryptosporidium in collected feces of Canada geese. The purpose of this follow-up study was to survey known Canada geese sites in three counties in Ohio (Lucas, Ottawa, and Wood) and to determine the prevalence of sites testing positive for Cryptosporidium. The sites included golf courses, cemeteries, public parks, and health care and teaching facilities. At each of 11 sites, 12 goose feces of wet and loose appearance were collected and manually compressed into one composite sample representing that site. The samples were tested for Cryptosporidium with a sensitive monoclonal enzyme immunoassay (EIA) method. In 2000 and 2001, nine of 11 sites (81.8 percent) and nine of 10 sites (90 percent), respectively, were positive for Cryptosporidium. The species or genotypes of Cryptosporidium found in the geese feces and their potential to infect humans is unknown. A survey of the literature indicates, however, that while C. parvum (human genotype) is the main cause of cryptosporidiosis in humans, C. parvum (zoonotic genotypes), C. meleagridis (bird genotype), and C. felis (cat genotype) have occasionally been isolated from infected people. Further research is required to define the public health importance of Cryptosporidium in feces of Canada geese and other bird species.

Animals↗

Colonization of Syrian hamsters with streptomycin resistant Campylobacter jejuni.

A streptomycin resistant Campylobacter jejuni inoculated per os into two populations of Syrian hamsters (one endemically harboring C. jejuni, the other free of C. jejuni) established chronic colonization of the organism in both groups. Diet, steroid administration, age of hamsters or prior exposure to C. jejuni did not appreciably alter incidence of diarrhea or colonization of C. jejuni. The majority of hamsters sampled during the course of the experiment (1 to 22 weeks) shed streptomycin resistant C. jejuni in the feces. In four hamsters sampled at 14, 17, 19, and 22 weeks, post inoculation, streptomycin resistant C. jejuni were recovered in ileal, cecal, jejunal, duodenal and colonic contents (10(4) to 10(7) colony forming units/gram of intestinal content). The hamster appears to be a potentially useful model for the study of intestinal colonization of enteropathogenic C. jejuni. Hamsters shedding C. jejuni in their feces for extended periods of time should be considered a zoonotic threat to both pet owners and laboratory personnel.

Animals↗

Animal coronaviruses: what can they teach us about the severe acute respiratory syndrome?

In 2002, a new coronavirus (CoV) emerged in the People's Republic of China, associated with a severe acute respiratory syndrome (SARS) and mortality in humans. The epidemic rapidly spread throughout the world before being contained in 2003, although sporadic cases occurred thereafter in Asia. The virus is thought to be of zoonotic origin from a wild animal reservoir (Himalayan palm civets [Paguma larvata] are suspected), but the definitive host is unknown. There is concern about possible transmission of SARS CoV to rodents or domestic cats (as proven experimentally) with perpetuation of the disease in these species. In livestock and poultry, CoVs are recognised causes of enteric and respiratory infections that are often fatal in young animals. Although the emergence of SARS surprised the medical community, veterinary coronavirologists had previously isolated CoVs from wildlife and documented their interspecies transmission to livestock. Furthermore, scientists were aware of compelling evidence pointing to the emergence of new CoV strains and the mutation of existing strains resulting in new disease syndromes in animals, but the evolution and disease impact of CoVs was not widely appreciated before SARS. This review focuses on the comparative pathogenesis of CoV infections, including the factors that accentuate CoV respiratory disease, with emphasis on livestock and poultry. The goal is to provide insights into CoV transmission and disease mechanisms that could potentially be applicable to SARS, highlighting the contributions of veterinary scientists to this area of study. Such examples illustrate the need for communication and collaboration between the veterinary and medical communities to understand and control emerging zoonotic diseases of the 21st Century.

Animals↗

Using HIV-1 sequence variability to explore virus biology.

Human immunodeficiency virus type 1 (HIV-1) only recently established an epidemic world-wide infection in the human population. The virus persists in the human host through active replication and is able to avoid clearance by the immune system. Active replication is an important component of the rapid evolutionary potential of HIV-1, a potential which manifests itself in the evolution of immune escape variants, drug resistant variants, and variants with the ability to use different cell surface coreceptors in conjunction with CD4. Multiple zoonotic introductions, compartmentalization of virus replication in the body, and genetic bottlenecks associated with sampling during transmission, antiretroviral therapy, and geographic and/or host population isolation further contribute to the range of sequences present in extant viruses. The sum of the history of all of these phenomena is reflected in HIV-1 sequence variability, and most of these phenomena are ongoing today. Here we review the use of HIV-1 sequence variability to explore its underlying biology.

Animals↗

Preventive and therapeutic approaches to viral agents of bioterrorism.

Certain viruses, such as those that cause smallpox and hemorrhagic fevers, have been identified as possible bioterrorism agents by the Centers for Disease Control and Prevention. They have been designated as potential threats because large quantities can be propagated in cell culture, they are transmissible as aerosols and, for the most part, there are only limited vaccine and pharmaceutical strategies for either prevention or treatment of established infection. An additional concern is the potential to genetically modify these agents to enhance virulence or promote resistance to vaccines or identified antivirals. Although the major impact of these agents is human illness, the release of zoonotic agents, such as the Nipah virus, would have consequences for both humans and animals because infected and noninfected animals might need to be sacrificed to control the spread of infection. Continued research is necessary to develop effective strategies to limit the impact of these biological threats.

Animals↗

Vaccine design for severe acute respiratory syndrome coronavirus.

Severe acute respiratory syndrome (SARS) is an emerging infectious disease caused by a new coronavirus (SARS-CoV). Recent studies suggest that SARS-CoV is zoonotic and may have a broad host range besides humans. Although the global outbreak of SARS has been contained, there are serious concerns over its re-emergence and bioterrorism potential. As a part of preparedness, development of a safe and effective vaccine is one of the highest priorities in fighting SARS. A number of candidate vaccines, using a variety of approaches, are under development. The first vaccine tested in clinical trial is made from the inactivated form of SARS-CoV. Several live attenuated, genetically engineered or vector vaccines encoding the SARS-CoV spike (S) protein have been in pre-clinical studies. These vaccine candidates are effective in terms of eliciting protective immunity in the vaccinated animals. However, caution should be taken with the safety of whole virus or full-length S protein-based immunogens in humans because they may induce harmful immune or inflammatory responses. We propose to use the receptor-binding domain (RBD) of SARS-CoV S protein (residues 318--510) for developing a safe and effective subunit SARS vaccine, as it is not only a functional domain that mediates virus-receptor binding but also a major neutralization determinant of SARSCoV. It has been demonstrated that the RBD of SARS-CoV S protein contains multiple conformational epitopes capable of inducing highly potent neutralizing antibody responses and protective immunity.

Animals↗