Public health risk from avian influenza viruses

Since 1997, avian influenza (AI) virus infections in poultry have taken on new significance, with increasing numbers of cases involving bird-to-human transmission and the resulting production of clinically severe and fatal human infections. Such human infections have been sporadic and are caused by H7N7 and H5N1 high-pathogenicity (HP) and H9N2 low-pathogenicity (LP) AI viruses in Europe and Asia. These infections have raised the level of concern by human health agencies for the potential reassortment of influenza virus genes and generation of the next human pandemic influenza A virus. The presence of endemic infections by H5N1 HPAI viruses in poultry in several Asian countries indicates that these viruses will continue to contaminate the environment and be an exposure risk with human transmission and infection. Furthermore, the reports of mammalian infections with H5N1 AI viruses and, in particular, mammal-to-mammal transmission in humans and tigers are unprecedented. However, the subsequent risk for generating a pandemic human strain is unknown. More international funding from both human and animal health agencies for diagnosis or detection and control of AI in Asia is needed. Additional funding for research is needed to understand why and how these AI viruses infect humans and what pandemic risks they pose.     

Antigenic relatedness of pigeon herpes encephalomyelitis virus to other avian herpesviruses

Pigeon herpes encephalomyelitis virus (PHEV) was compared with seven avian herpesviruses for antigenic relatedness using monospecific antisera and the indirect fluorescent-antibody (IFA), agar-gel-immunodiffusion, and serum-neutralization tests. No antigenic relationship was detected between PHEV and Marek's disease virus, turkey herpesvirus, infectious laryngotracheitis virus, and duck enteritis virus. A common precipitating antigen was detected between the PHEV and pigeon herpesvirus (PHV), owl herpesvirus (OHV), and falcon herpesvirus (FHV). These four viruses also cross-reacted in the IFA test. Weak neutralizing activity was detected only between PHV antiserum and PHEV. These results suggest that the PHEV should be classified as a herpesvirus related to, but distinct from, the PHV-OHV-FHV group of viruses with which it shares common antigens.     

禽流感病毒对人类健康的危险

本文根据近年来国内外大量相关研究报道,从流感病毒的生物学特性、人类流感病毒的历史与禽流感病毒的关系、近年人类感染禽流感病毒H5N1的发生情况与H5N1病毒的进化、实验室诊断和防治技术现状等方面,系统论述并提出禽流感病毒对人类健康已经构成危险,再次强调必须及时监测和识别新的流感毒株,以有效预防和控制该病发生和传播。     

猪正面临着禽型流感病毒的威胁

到目前为止,H5N1亚型禽流感病毒还没有在猪农中引起普遍恐慌。但是,禽流感病毒在近十年来的若干重大变化,已经使猪在密切接触受感染的家禽时就受到危害,但这在猪群中的传播并不容易。禽流感的传染史表明,持续不断进行监控对极早发现流感具有重要作用。     

Serological evidence for exposure to avian influenza viruses within poultry workers in southern China

The risk of infection with avian influenza viruses for poultry workers is relatively unknown in China, and study results are often biased by the notification of only the severe human cases. Protein microarray was used to detect binding antibodies to 13 different haemagglutinin (HA1‐part) antigens of avian influenza A(H5N1), A(H7N7), A(H7N9) and A(H9N2) viruses, in serum samples from poultry workers and healthy blood donors collected in the course of 3 years in Guangdong Province, China. Significantly higher antibody titre levels were detected in poultry workers when compared to blood donors for the most recent H5 and H9 strains tested. These differences were most pronounced in younger age groups for antigens from older strains, but were observed in all age groups for the recent H5 and H9 antigens. For the H7 strains tested, only poultry workers from two retail live poultry markets had significantly higher antibody titres compared to blood donors.     

Pathogenic and immunogenic responses in turkeys following in ovo exposure to avian metapneumovirus subtype C

Commercial turkey eggs, free of antibodies to avian metapneumovirus subtype C (aMPV/C), were inoculated with aMPV/C at embryonation day (ED) 24. There was no detectable effect of virus inoculation on the hatchability of eggs. At 4 days post inoculation (DPI) (the day of hatch (ED 28)) and 9 DPI (5 days after hatch), virus replication was detected by quantitative RT-PCR in the turbinate, trachea and lung but not in the thymus or spleen. Mild histological lesions characterized by lymphoid cell infiltration were evident in the turbinate mucosa. Virus exposure inhibited the mitogenic response of splenocytes and thymocytes and upregulated gene expression of IFN-γ and IL-10 in the turbinate tissue. Turkeys hatching from virus-exposed eggs had aMPV/C-specific IgG in the serum and the lachrymal fluid. At 3 week of age, in ovo immunized turkeys were protected against a challenge with pathogenic aMPV/C.     

食品生产用动物及其健康关乎人类健康

正益生元的概念相对较新,不易消化的食物成分(如不能消化的低聚糖)可被一种或多种对肠道生理具有益作用的细菌选择性发酵,一些益生元可选择性地刺激肠道中内源乳酸菌和双歧杆菌的生长,增加益生菌数量,从而改善宿主健康。如果特定有益菌不存在,益生元就没有用处。同样,如果环境不利,活菌也不会产生效力。最近提出了共生概念,即同时含有益生元和益生菌属性的食物才是有益健康的功能食品。1益生菌和益生元能够改善动物健康、生产性     

Public health response to an imported case of canine melioidosis

Melioidosis in humans presents variably as fulminant sepsis, pneumonia, skin infection and solid organ abscesses. It is caused by Burkholderia pseudomallei, which in the United States is classified as a select agent, with “potential to pose a severe threat to both human and animal health, to plant health or to animal and plant products” (Federal Select Agent Program, http://www.selectagents.gov/ , accessed 22 September 2016). Burkholderia pseudomallei is found in soil and surface water in the tropics, especially South‐East Asia and northern Australia, where melioidosis is endemic. Human cases are rare in the United States and are usually associated with travel to endemic areas. Burkholderia pseudomallei can also infect animals. We describe a multijurisdictional public health response to a case of subclinical urinary B. pseudomallei infection in a dog that had been adopted into upstate New York from a shelter in Thailand. Investigation disclosed three human contacts with single, low‐risk exposures to the dog's urine at his residence, and 16 human contacts with possible exposure to his urine or culture isolates at a veterinary hospital. Contacts were offered various combinations of symptom/fever monitoring, baseline and repeat B. pseudomallei serologic testing, and antibiotic post‐exposure prophylaxis, depending on the nature of their exposure and their personal medical histories. The dog's owner accepted recommendations from public health authorities and veterinary clinicians for humane euthanasia. A number of animal rescue organizations actively facilitate adoptions into the United States of shelter dogs from South‐East Asia. This may result in importation of B. pseudomallei into almost any community, with implications for human and animal health.     

Neutralising antibody to herpesviruses dervied from wildebeest and hartebeest in wild animals in East Africa.

The sera of 728 game animals, collected in East Africa, were tested for neutralising antibody to a strain (WC11) of wildebeest herpesvirus, which is an important cause of malignant catarrhal fever of cattle. In addition, 290 of these sera were tested for neutralising activity against a closely related herpesvirus (K/30) from hartebeest (Alcelaphus sp.). Antibody was frequently present in three species of the subfamily Alcelaphinae (wildebest, hartebeest and topi) and one of the subfamily Hippotraginae (oryx). No activity was found in the sera of nine other species of four additional subfamilies. The proportion of hartebeest sera positive for WC11 virus (60 per cent) was not significantly different from that neutralising the K/30 isolate (77 per cent) and antibody titres against the two agents did not differ significantly. Of 62 topi sera 40 per cent neutralised WC11 virus, while all of three oryx sera were positive. It is suggested that the antibody detected in hartebeest, topi and oryx was induced by infection with viruses related to, but not identical with, the WC11 and K/30 strains. Some characteristics of the latter indicated that it was not the usual herpesvirus of hartebeest and may have been derived from wildebeest. It is proposed that the group of viruses involved should be provisionally designated as 'alcelaphine herpesviruses' in order to separate them from the rest of the 'bovid' herpesviruses, a name proposed by the Herpesvirus Sbucommittee of the International Committee on the Nomenclature of Viruses.     

Analysis of human infectious avian influenza virus: Hemagglutinin genetic characteristics in Asia and Africa from 2004 to 2009

In the present study, we used nucleotide and protein sequences of avian influenza virus H5N1, which were obtained in Asia and Africa, analyzed HA proteins using ClustalX1.83 and MEGA4.0, and built a genetic evolutionary tree of HA nucleotides. The analysis revealed that the receptor specificity amino acid of A/HK/213/2003, A/Turkey/65596/2006 and etc mutated into QNG, which could bind with á–2, 3 galactose and á–2, 6 galactose. A mutation might thus take place and lead to an outbreak of human infections of avian influenza virus. The mutations of HA protein amino acids from 2004 to 2009 coincided with human infections provided by the World Health Organization, indicating a “low–high–highest–high–low” pattern. We also found out that virus strains in Asia are from different origins: strains from Southeast Asia and East Asia are of the same origin, whereas those from West Asia, South Asia and Africa descend from one ancestor. The composition of the phylogenetic tree and mutations of key site amino acids in HA proteins reflected the fact that the majority of strains are regional and long term, and virus diffusions exist between China, Laos, Malaysia, Indonesia, Azerbaijan, Turkey and Iraq. We would advise that pertinent vaccines be developed and due attention be paid to the spread of viruses between neighboring countries and the dangers of virus mutation and evolution.