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1.
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2.
The introduction of swine or avian influenza (AI) viruses in the human population can set the stage for a pandemic, and many fear that the Asian H5N1 AI virus will become the next pandemic virus. This article first compares the pathogenesis of avian, swine and human influenza viruses in their natural hosts. The major aim was to evaluate the zoonotic potential of swine and avian viruses, and the possible role of pigs in the transmission of AI viruses to humans. Cross-species transfers of swine and avian influenza to humans have been documented on several occasions, but all these viruses lacked the critical capacity to spread from human-to-human. The extreme virulence of H5N1 in humans has been associated with excessive virus replication in the lungs and a prolonged overproduction of cytokines by the host, but there remain many questions about the exact viral cell and tissue tropism. Though pigs are susceptible to several AI subtypes, including H5N1, there is clearly a serious barrier to infection of pigs with such viruses. AI viruses frequently undergo reassortment in pigs, but there is no proof for a role of pigs in the generation of the 1957 or 1968 pandemic reassortants, or in the transmission of H5N1 or other wholly avian viruses to humans. The major conclusion is that cross-species transmission of influenza viruses per se is insufficient to start a human influenza pandemic and that animal influenza viruses must undergo dramatic but largely unknown genetic changes to become established in the human population.  相似文献   

3.
For the response to a zoonotic disease outbreak to be effective, animal health authorities and disease specialists must be involved. Animal health measures are commonly directed at known diseases that threaten the health of animals and impact owners. The measures have long been applied to zoonotic diseases, including tuberculosis and brucellosis, and can be applied to emerging diseases. One Health (veterinary, public, wildlife and environmental health) and all-hazards preparedness work have done much to aid interdisciplinary understanding and planning for zoonotic diseases, although further improvements are needed. Actions along the prevention, preparedness, response and recovery continuum should be considered. Prevention of outbreaks consists largely of import controls on animals and animal products and biosecurity. Preparedness includes situational awareness, research, tool acquisition, modelling, training and exercises, animal movement traceability and policy development. Response would include detection systems and specialized personnel, institutions, authorities, strategies, methods and tools, including movement control, depopulation and vaccination if available and appropriate. The specialized elements would be applied within a general (nationally standardized) system of response. Recovery steps begin with continuity of business measures during the response and are intended to restore pre-event conditions. The surveillance for novel influenza A viruses in swine and humans and the preparedness for and response to the recent influenza pandemic illustrate the cooperation possible between the animal and public health communities.  相似文献   

4.
During the last 10 years, scientists have grown increasingly aware that emerging respiratory viruses are often zoonotic in their origin. These infections can originate from or be amplified in livestock. Less commonly recognized are instances when humans have transmitted their respiratory pathogens to animals (reverse zoonoses). Even with this knowledge of viral exchange at the human–livestock interface, few studies have been conducted to understand this cross‐over. In this pilot study, we examined persons with influenza‐like illness at an outpatient clinic for evidence of infection with novel zoonotic respiratory pathogens in rural North Carolina where there are dense swine and poultry farming. Environmental air sampling was also conducted. From July 2016 to March 2017, a total of 14 human subjects were enrolled and sampled, and 192 bioaerosol samples were collected. Of the 14 human subject samples molecularly tested, three (21.4%) were positive for influenza A, one (7.1%) for influenza B and one (7.1%) for human enterovirus. Of the 192 bioaerosol samples collected and tested by real‐time RT‐PCR or PCR, three (1.6%) were positive for influenza A and two (1.0%) for adenovirus. No evidence was found for novel zoonotic respiratory viruses.  相似文献   

5.
Pigs have been associated with several episodes of influenza outbreaks in the past and are considered to play a significant role in the ecology of influenza virus. The recent 2009 pandemic influenza A/H1N1 virus originated from swine and not only did it cause widespread infection in humans, but was also transmitted back to swine in Asia, Europe and America. What may be the prevailing situation in Africa, particularly in sub‐Saharan Africa, with respect to the circulation of classical swine or pandemic influenza? The ecology of influenza viruses, as well as the epidemiology of human or animal influenza, is poorly understood in the region. In particular, little is known about swine influenza in Africa despite the relevance of this production in the continent and the widespread pig husbandry operations in urban and rural areas. In this review, the gap in the knowledge of classical and pandemic swine influenza is attributed to negligence of disease surveillance, as well as to the economic and public health impact that the disease may cause in sub‐Saharan Africa. However, emerging serological and virological evidence of swine influenza virus in some countries in the region underscores the importance of integrated surveillance to better understand the circulation and epidemiology of swine influenza, a disease of global economic and public health importance.  相似文献   

6.
Variant influenza viruses are swine‐origin influenza A viruses that cause illness in humans. Surveillance for variant influenza A viruses, including characterization of exposure settings, is important because of the potential emergence of novel influenza viruses with pandemic potential. In Minnesota, we have documented variant influenza A virus infections associated with swine exposure at live animal markets.  相似文献   

7.
The close genetic relationship of noroviruses and sapoviruses found in animals and humans has raised the question whether these viruses have a zoonotic potential. Transmission from animals to humans and vice versa would have far-reaching consequences for epidemiology and food safety. So far animal noro- and sapoviruses have not been found in humans. However detection of human noroviruses in animals as well as simultaneous presence of animal and human viruses in bivalve molluscs suggest a risk of transmission. Furthermore, antibodies against animal noroviruses were detected in humans as well as antibodies against human noroviruses in swine. Experimental infection of gnotobiotic calves and pigs with human noroviruses demonstrated that virus replication and seroconversion can occur. Accordingly the possible role of noro- and sapoviruses as zoonotic agents needs to be further investigated.  相似文献   

8.
The zoonotic introduction of an animal pathogen into the human population and the subsequent extension or alteration of its host range leading to the successful maintenance of the corresponding pathogen by human‐to‐human transmission pose a serious risk for world‐wide health care. Such a scenario occurred for instance by the introduction of simian immunodeficiency viruses into the human population resulting in the human immunodeficiency viruses (HIV) and the subsequent AIDS pandemic or the proposed recent host range switch of the SARS coronavirus from a presently unknown animal species to humans. The occurrence of zoonotic transmissions of animal viruses to humans is a permanent threat to human health and is even increased by changes in the human lifestyle. In this review, the potential of the zoonotic transmission of bovine, feline and equine foamy retroviruses will be discussed in the light of well‐documented cases of zoonotic transmissions of different simian foamy viruses to humans.  相似文献   

9.
Influenza A viruses (IAVs) have both zoonotic and anthroponotic potential and are of public and veterinary importance. Swine are intermediate hosts and ‘mixing vessels’ for generating reassortants, progenies of which may harbour pandemic propensity. Swine handlers are at the highest risk of becoming infected with IAVs from swine but there is little information on the ecology of IAVs at the human–animal interface in Africa. We analysed and characterized nasal and throat swabs from swine and farmers respectively, for IAVs using RT‐qPCR, from swine farms in the Ashanti region, Ghana. Sera were also analysed for IAVs antibodies and serotyped using ELISA and HI assays. IAV was detected in 1.4% (n = 17/1,200) and 2.0% (n = 2/99) of swine and farmers samples, respectively. Viral subtypes H3N2 and H1N1pdm09 were found in human samples. All virus‐positive swine samples were subtyped as H1N1pdm09 phylogenetically clustering closely with H1N1pdm09 that circulated among humans during the study period. Phenotypic markers that confer sensitivity to Oseltamivir were found. Serological prevalence of IAVs in swine and farmers by ELISA was 3.2% (n = 38/1,200) and 18.2% (n = 18/99), respectively. Human H1N1pdm09 and H3N2 antibodies were found in both swine and farmers sera. Indigenous swine influenza A viruses and/or antibodies were not detected in swine or farmers samples. Majority (98%, n = 147/150) of farmers reported of not wearing surgical mask and few (4%, n = 6) reported to wear gloves when working. Most (n = 74, 87.7%) farmers reported of working on the farm when experiencing influenza‐like illness. Poor husbandry and biosafety practices of farmers could facilitate virus transmission across the human–swine interface. Farmers should be educated on the importance of good farm practices to mitigate influenza transmission at the human–animal interface.  相似文献   

10.
Swine coronaviruses (SCoVs) are one of the most devastating pathogens affecting the livelihoods of farmers and swine industry across the world. These include transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), porcine respiratory coronavirus (PRCV), porcine hemagglutinating encephalomyelitis virus (PHEV), swine acute diarrhea syndrome coronavirus (SADS-CoV), and porcine delta coronavirus (PDCoV). Coronaviruses infect a wide variety of animal species and humans because these are having single stranded-RNA that accounts for high mutation rates and thus could break the species barrier. The gastrointestinal, cardiovascular, and nervous systems are the primary organ systems affected by SCoVs. Infection is very common in piglets compared to adult swine causing high mortality in the former. Bat is implicated to be the origin of all CoVs affecting animals and humans. Since pig is the only domestic animal in which CoVs cause a wide range of diseases; new coronaviruses with high zoonotic potential could likely emerge in the future as observed in the past. The recently emerged severe acute respiratory syndrome coronavirus virus-2 (SARS-CoV-2), causing COVID-19 pandemic in humans, has been implicated to have animal origin, also reported from few animal species, though its zoonotic concerns are still under investigation. This review discusses SCoVs and their epidemiology, virology, evolution, pathology, wildlife reservoirs, interspecies transmission, spill-over events and highlighting their emerging threats to swine population. The role of pigs amid ongoing SARS-CoV-2 pandemic will also be discussed. A thorough investigation should be conducted to rule out zoonotic potential of SCoVs and to design appropriate strategies for their prevention and control.  相似文献   

11.
Since the first detection of human H3N2 influenza virus in Taiwanese pigs in 1970, infection of pigs with wholly human viruses has been known to occur in other parts of the world. These viruses, referred to as human‐like H3N2 viruses, have been known to cause clinical and subclinical infections of swine populations. Due to the paucity and complete unavailability of information on transmission of influenza viruses from other species, especially humans, to swine in Nigeria and Ghana, respectively, this study was designed to investigate the presence and prevalence of a human strain of influenza A (H3N2) in swine populations at three locations in two cities within these two West African countries in January and February, 2014. Using stratified random technique, nasal swab specimens were collected from seventy‐five (75) pigs at two locations in Ibadan, Nigeria and from fifty (50) pigs in Kumasi, Ghana. These specimens were tested directly by a sensitive Quantitative Solid Phase Antigen‐detection Sandwich ELISA using anti‐A/Brisbane/10/2007 haemagglutinin monoclonal antibody. Influenza virus A/Brisbane/10/2007 (H3N2) was detected among pigs at the three study locations, with an aggregate prevalence of 4.0% for the two locations in Ibadan, Nigeria and also 4.0% for Kumasi, Ghana. Transmission of influenza viruses from other species to swine portends serious sinister prospects for genetic reassortment and evolvement of novel viruses. We therefore recommend that further studies should be carried out to investigate the presence of other circulating human and avian influenza viruses in swine populations in West Africa and also determine the extent of genetic reassortment of strains circulating among these pigs. This would provide an early warning system for detection of novel influenza viruses, which could have pandemic potentials.  相似文献   

12.
In 2009, a pandemic influenza A virus (pH1N1) spread globally in humans and infected a broad range of captive animals with close human contact. In February 2014, a pH1N1 virus was isolated from a sloth bear with respiratory signs at a US zoo, demonstrating that recurring epidemics present an ongoing threat to animals, including threatened species. This is the first report of pH1N1 infection in sloth bears. To understand the sloth bear virus within the global context of pH1N1, phylogenetic trees were inferred including full‐length sequences from available non‐human, non‐swine hosts, representing four families in the order Carnivora and one order of birds. A combination of phylogenetic and epidemiological evidence strongly suggests the sloth bear was infected with a human‐origin pH1N1 virus, supporting the implementation of biosecurity measures to protect human and animal health.  相似文献   

13.
Zoonotic agents challenging the world every year afresh are influenza A viruses. In the past, human pandemics caused by influenza A viruses had been occurring periodically. Wild aquatic birds are carriers of the full variety of influenza virus A subtypes, and thus, most probably constitute the natural reservoir of all influenza A viruses. Whereas avian influenza viruses in their natural avian reservoir are generally of low pathogenicity (LPAIV), some have gained virulence by mutation after transmission and adaptation to susceptible gallinaceous poultry. Those so-called highly pathogenic avian influenza viruses (HPAIV) then cause mass die-offs in susceptible birds and lead to tremendous economical losses when poultry is affected. Besides a number of avian influenza virus subtypes that have sporadically infected mammals, the HPAIV H5N1 Asia shows strong zoonotic characteristics and it was transmitted from birds to different mammalian species including humans. Theoretically, pandemic viruses might derive directly from avian influenza viruses or arise after genetic reassortment between viruses of avian and mammalian origin. So far, HPAIV H5N1 already meets two conditions for a pandemic virus: as a new subtype it has been hitherto unseen in the human population and it has infected at least 438 people, and caused severe illness and high lethality in 262 humans to date (August 2009). The acquisition of efficient human-to-human transmission would complete the emergence of a new pandemic virus. Therefore, fighting H5N1 at its source is the prerequisite to reduce pandemic risks posed by this virus. Other influenza viruses regarded as pandemic candidates derive from subtypes H2, H7, and H9 all of which have infected humans in the past. Here, we will give a comprehensive overview on avian influenza viruses in concern to their zoonotic potential.  相似文献   

14.
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15.
Influenza A viruses circulate in swine and can spread rapidly among swine when housed in close proximity, such as at agricultural fairs. Youth who have close and prolonged contact with influenza‐infected swine at agricultural fairs may be at increased risk of acquiring influenza virus infection from swine. Animal and human health officials have issued written measures to minimize influenza transmission at agricultural exhibitions; however, there is little information on the knowledge, attitudes, and practice (KAP) of these measures among animal exhibitors. After an August 2016 outbreak of influenza A(H3N2) variant (“H3N2v”) virus infections (i.e., humans infected with swine influenza viruses) in Michigan, we surveyed households of animal exhibitors at eight fairs (including one with known H3N2v infections) to assess their KAP related to variant virus infections and their support for prevention measures. Among 170 households interviewed, most (90%, 151/167) perceived their risk of acquiring influenza from swine to be low or very low. Animal exhibitor households reported high levels of behaviours that put them at increased risk of variant influenza virus infections, including eating or drinking in swine barns (43%, 66/154) and hugging, kissing or snuggling with swine at agricultural fairs (31%, 48/157). Among several recommendations, including limiting the duration of swine exhibits and restricting eating and drinking in the animal barns, the only recommendation supported by a majority of households was the presence of prominent hand‐washing stations with a person to monitor hand‐washing behaviour (76%, 129/170). This is a unique study of KAP among animal exhibitors and highlights that animal exhibitor households engage in behaviours that could increase their risk of variant virus infections and have low support for currently recommended measures to minimize infection transmission. Further efforts are needed to understand the lack of support for recommended measures and to encourage healthy behaviours at fairs.  相似文献   

16.
The zoonotic introduction of an animal pathogen into the human population and the subsequent extension or alteration of its host range leading to the successful maintenance of the corresponding pathogen by human-to-human transmission pose a serious risk for world-wide health care. Such a scenario occurred for instance by the introduction of simian immunodeficiency viruses into the human population resulting in the human immunodeficiency viruses (HIV) and the subsequent AIDS pandemic or the proposed recent host range switch of the SARS coronavirus from a presently unknown animal species to humans. The occurrence of zoonotic transmissions of animal viruses to humans is a permanent threat to human health and is even increased by changes in the human lifestyle. In this review, the potential of the zoonotic transmission of bovine, feline and equine foamy retroviruses will be discussed in the light of well-documented cases of zoonotic transmissions of different simian foamy viruses to humans.  相似文献   

17.
H9N2亚型禽流感病毒已在世界范围内的禽类中分离确认,并被证实可以传播到人类和低等哺乳类动物。对于它存在的潜在危害已经越来越多地受到关注,相关的研究也相继开展。许多遗传进化的分析为禽或猪流感可以直接感染人提供了证据,通过在人体的适应或与人流感病毒基因重组,可以形成新的病毒株,引起人类流感疫情暴发。文章提示应当密切监控H9N2亚型禽流感病毒,防止人类流感大流行。  相似文献   

18.
Influenza A virus (IAV) infection in swine plays an important role in the ecology of influenza viruses. The emergence of new IAVs comes through different mechanisms, with the genetic reassortment of genes between influenza viruses, also originating from different species, being common. We performed a genetic analysis on 179 IAV isolates from humans (n. 75) and pigs (n. 104) collected in Northern Italy between 2010 and 2015, to monitor the genetic exchange between human and swine IAVs. No cases of human infection with swine strains were noticed, but direct infections of swine with H1N1pdm09 strains were detected. Moreover, we pointed out a continuous circulation of H1N1pdm09 strains in swine populations evidenced by the introduction of internal genes of this subtype. These events contribute to generating new viral variants—possibly endowed with pandemic potential—and emphasize the importance of continuous surveillance at both animal and human level.  相似文献   

19.
Shiga toxin (Stx) [Verotoxin (VT)]-producing Escherichia coli (STEC), also called enterohaemorrhagic E. coli or VTEC are emerging zoonotic agents and became most important as human pathogens, particularly in the industrialized countries. Production of cytotoxins, also called Stx or VT, is the major pathogenicity determinant of STEC, which can cause life-threatening haemorrhagic diseases in humans. The spectrum of STEC phenotypes is diverse and domestic and wildlife animals constitute important reservoirs for these bacteria. STEC are spread from animal faeces to the environment, water and food. Ingestion of contaminated foodstuff and water, as well as contact with the environment, STEC-excreting animals or humans are the major sources of human infection. Economical changes in animal and food production, alteration of consumer habits and lack of specific immune response, particularly in urbanized populations, have contributed to the recent spread of STEC as a zoonotic agent. Supranational surveillance networks as well as national reference laboratories as sentinels play an important role in the prevention and control of STEC infections in humans. Development of new vaccines and probiotics may serve as future tools to control the spread of STEC in animals and humans.  相似文献   

20.
Although swine origin A/H1N1/2009 influenza virus (hereafter "pH1N1″) has been detected in swine in 20 countries, there has been no published surveillance of the virus in African livestock. The objective of this study was to assess the circulation of influenza A viruses, including pH1N1 in swine in Cameroon, Central Africa. We collected 108 nasal swabs and 98 sera samples from domestic pigs randomly sampled at 11 herds in villages and farms in Cameroon. pH1N1 was isolated from two swine sampled in northern Cameroon in January 2010. Sera from 28% of these herds were positive for influenza A by competitive ELISA and 92.6% of these swine showed cross reactivity with pandemic A/H1N1/2009 influenza virus isolated from humans. These results provide the first evidence of this virus in the animal population in Africa. In light of the significant role of swine in the ecology of influenza viruses, our results call for greater monitoring and study in Central Africa.  相似文献   

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