We've another report of large cats, kept in a Chinese Zoo, infected by the H5N1 virus. This time - instead of Asian tigers - the victims are African lions.
Despite reporting only 15 human H5N1 infections (and 6 deaths) over the past 5 years, and with H7N9 and H5N6 making bigger a splash in recent years, we continue to see evidence that HPAI H5N1 is alive and well on the Chinese Mainland.
Last May, in Fatal H5N1 Infection In Tigers By Different Reassortant Viruses - China, we looked at 5 recent tiger infections and/or deaths from H5N1 over 2014-2015.
Three of these infections occurred in Yunnan Province over an 18 month period, and remarkably, all three viruses represented different clades of H5N1.
- A/tiger /Yunnan /tig1404 /2014(H5N1) subclade 22.214.171.124e reassortant with six internal genes from avian influenza A(H5N2) virus
- A/tiger /Yunnan /tig1412 /2014(H5N1) subclade 126.96.36.199b
- A/tiger /Yunnan /tig1508 /2015(H5N1) clade 188.8.131.52c reassortant with three internal genes from the A(H9N2) avian virus.
In summary, all of mutations/substitutions of the gene segments of the tiger originated viruses could contribute to the enhancement of virulence or the increase of the H5N1 virus binding to the α2-6 receptor.
The authors also documented replication and pathogenicity in mice, and a loss of effectiveness of China's RE-6 vaccine against the most recent (Aug 2015) tiger isolate.
As we've noted previously (see Subclinical Highly Pathogenic Avian Influenza Virus Infection among Vaccinated Chickens, China) - poultry vaccines don’t always prevent infection – sometimes they only mask the symptoms, allowing the virus to spread and evolve under the radar.
This `healthy facade' likely explains why so many zoo animals have been infected with H5N1, as raw poultry is often used to feed carnivorous animals in captivity.
While the following government report lacks some crucial details (the event was described only as `recent'), it does provide a pretty good narrative of the incident.
Hubei Provincial People's Government portal www.hubei.gov.cn
Source: Hubei Emergency Management website
Recently, the provincial wild animal epidemic sources and disease monitoring center has successfully disposed of together Ezhou African lion H5N1 infection anomalies.
Provincial wildlife epidemic sources and disease monitoring center Ezhou monitoring stations, the city zoo SEG two African lions (1 male 1 female) high fever, dying, sudden abnormal situation, the provincial wild animal epidemic sources and disease monitoring immediate establishment of a panel by the center of Changchun military Medical veterinary hospital, Huazhong Agricultural University and other emergency experts, arrived in the afternoon Ezhou, two African lions to carry out isolation and treatment, to identify the cause and related investigations. Male African lion condition suddenly deteriorated because he died soon afterwards. The other a female African lion, the careful treatment of the Expert Group has been recovered, and other park animals not see the death of the new phenomenon.
Group of Experts on the African lion was death autopsy, found it impossible to exclude the possibility of death from communicable diseases, immediately took samples back to the laboratory. Provincial wildlife epidemic sources and disease monitoring center immediately to the State Forestry Protection Department, Monitoring Station, the Provincial Forestry Department and the provincial joint prevention and control office to report in a timely manner to Ezhou health planning, forestry and animal husbandry and veterinary department informed, and requested the zoo, take Feng Yuan, disinfection and other treatment, the African lion death was burned deep disposal, the park of birds have been vaccinated. Meanwhile, the province also organized to go to other zoos technology, domestication and breeding places to carry out sample testing, tracing investigation, as of now, the province found no abnormalities other wildlife.
African lion samples Conservancy Military Medical Veterinary Hospital detect H5N1 influenza virus gene sequence homology with the white tiger isolates 2015 Nanning death up to 99%. Experts believe that a comprehensive analysis, African lions since the H5N1 flu virus and bacterial mixed infection caused by lung, kidney and other organ damage and death.
To further strengthen the province's wild animal epidemic sources and disease monitoring and prevention and control work, the provincial Forestry Department issued a document requiring the forestry sector at all levels, in accordance with the requirements of the focus period, to strengthen prevention and control of wild animal epidemic sources and disease monitoring, so early detection, early reporting, early disposal; further implement the ban order of birds, wildlife and out Closure transport permits, each zoo prohibited person close contact with wild animals, wild animals in captivity breeding strengthening workplace health supervision. (Provincial Forestry Department)
As we discussed last year in HPAI H5: Catch As Cats Can,
felines (and canines) are susceptible to HPAI H5 viruses, including H5N1.
In 2006, virologist C. A. Nidom of the Institute of Tropical Disease, Airlangga University demonstrated that of 500 cats he tested in and around Jakarta, 20% had antibodies for the H5N1 bird flu virus. Findings that prompted the FAO in 2007 to warn that: Avian influenza in cats should be closely monitored.
More recently, in 2012 the OIE reported on Cats Infected With H5N1 in Israel, while in early 2015 we saw Guangxi Zoo Reports 2 Tiger Deaths Due To H5N1.
Just over a year ago we saw reports of Fatal H5N6 Avian Influenza Virus Infection in a Domestic Cat and Wild Birds in China. While last May, in Report: Skunks and Rabbits Can Catch And Shed Avian Flu, we saw evidence that other peridomestic animals are susceptible as well.
Although reports of H5N1 have declined out of Asia over the past few years (while surging in the Middle East and Africa), reports like the one today are a reminder that it remains a player in China's diverse avian flu ecology.