Viruses of Special Concern Highly Pathogenic Avian Influenza HPAI Human infections with novel avian influenza virus are concerning because flu changes rapidly, and animal flu viruses can change such that they may gain the ability to infect people easily and spread among people.
How is HPAI spread? Avian influenza viruses are spread through direct contact with infected birds or through contact with contaminated bedding, feed or water. Can humans be infected with HPAI? Some highly pathogenic avian flu viruses can infect people causing mild to severe respiratory illness. In most cases, people are infected after direct contact with birds that are sick with or died from highly pathogenic avian influenza.
Symptoms in infected people can include influenza-like illness e. Person-to-person transmission of avian influenza viruses is very rare. HPAI does not pose a health risk to the public. We report a case of human H7N9 virus infection in Jilin Province in northeastern China, an area not contiguous with provinces in which human cases have been previously reported Figure 1.
Furthermore, this case was associated with a small-scale poultry farm, not an LPM. Provinces in China in which human cases of infection with influenza A H7N9 virus have been confirmed gray shading.
On February 15, , a year-old man, owner of a small farm in Changchun, Jilin Province, experienced an isolated fever axillary temperature He had no history of underlying medical conditions. The man sought medical care that day at Jilin University Third Hospital and returned to the hospital on February 16, 17, and 19 with ongoing fever.
Radiographic imaging showed evidence of pneumonia; he received intravenous administration of azithromycin and xiyanping, a traditional Chinese medicine. On February 19, the man sought care at Jilin University First Hospital, where throat swab samples were taken.
The man recovered and was discharged from the hospital on March 7. The man denied exposure to poultry other than on his farm, including to poultry on other farms or in LPMs. He reported no contact with persons who had similar symptoms before onset of his illness.
As part of the case investigation, 68 close contacts of the case-patient were monitored for 7 days; 1 contact had influenza-like illness. Throat swab specimens were collected from this person on days 2 and 3 after symptom onset and tested for influenza A H7N9 by using real-time RT-PCR; results were negative.
The birds were turkeys, guinea fowl Numida meleagris , black-bone silkie chickens Gallus gallus domesticus , local chickens, and a goose.
Birds commingled in an egg production warehouse Figure 3 maintained by the case-patient and by 2 farmers hired in early January The warehouse was seldom cleaned and never disinfected.
The case-patient cared for the birds daily and did not use personal protective equipment. Timeline of introduction of new birds to the farm of the case-patient with influenza A H7N9 virus infection in Jilin Province, China, — Internal top and external views of the warehouse where poultry were housed on the farm of the case-patient who had confirmed influenza A H7N9 virus infection in February in Jilin Province, China.
Arrow indicates location of the chicken warehouse. In October , a group of silkie chickens and guinea fowl was introduced to the warehouse and subsequently exhibited signs of illness; many of these birds died during the next 3 months. A veterinarian reportedly diagnosed air sacculitis and enteritis; testing for influenza A was not performed. By January , all but 4 silkie chickens and 40 guinea fowl had died. More birds were added on February 3, but no further illness was noted until 2 additional flocks, totaling birds, arrived on February 10 and Asian H7N9 Outbreak Characterization.
CDC does not have any new or special recommendations for the U. CDC will keep you updated. Stay informed. Since Asian H7N9 is not spreading easily from person to person at this time, CDC does not recommend that people delay or cancel trips to China.
The World Health Organization also is watching this situation closely and does not recommend any travel restrictions. CDC advises travelers to China to take some common sense precautions, like not touching birds and washing hands often. Poultry and poultry products should be fully cooked. CDC will update its advice for travelers if the situation in China changes. View and download H7N9 Images. Get Email Updates. To receive email updates about this page, enter your email address: Email Address.
This is different from the H7N9 outbreaks in neighboring Guangxi Province, where showed a higher proportion of backyard poultry exposure among human cases [ 16 ]. Therefore, the Wenshan outbreak was quickly brought under control by closure of LPM and environmental disinfection.
HA genes of isolates from Wenshan mainly clustered with viruses from Guangxi provinces. However, the isolates from other newly emerged provinces clustered with different isolates from various regions of China [ 15 ]. However, there was no significant difference in fatality and severity in humans infected with either low or high pathogenicity H7N9 AIV [ 18 ]. However, all of the four Wenshan isolates did not contain any of the amino acid substitutions that are known to confer reduced inhibition by the NA inhibitor class of antivirals.
These results indicate that neuraminidase inhibitor antiviral drugs could still be effective for the treatment. Amino acid changes DK and DN in PB2 have been considered to be critical adaptations and virulence factors for infecting mammals. They have much higher proportions in human-isolated H7N9 viruses than in avian-isolated forms in all five waves [ 20 ]. In the Wenshan outbreak, no isolate presented K and N mutations, which reflects a direct cross-species transmission of H7N9 AIV from chickens to humans.
In this study, both epidemiological investigations of chicken sources and phylogenetic analyses of the genetic similarity of virus strains indicated that the source of infection is from Guangxi Province.
Guangxi is adjacent to Guangdong Province in the east, and it is one of two H7N9 origin centers the other one is YRD with the highest cumulative numbers of reported incidences of human infection with H7N9 AIV since [ 21 ]. The first laboratory-confirmed case in Guangxi was imported from neighboring Guangdong on January Soon after that, the H7N9 outbreak was detected in Wenshan City.
The transmission route spanned a long geographical region with spread from east to west. Similar findings from Chongqing also demonstrated a high positive rate of H7N9 infection in live chickens transported from other provinces between February and June [ 23 ].
However, due to the low pathogenicity of the H7N9 virus causing asymptomatic infections and circulating silently in chickens, it was impossible to predict a possible human infection by infected chickens without any laboratory tests [ 24 , 25 ] Thus, virological screening in chickens before cross-regional transportation is necessary to prevent H7N9 virus spread.
Our study documented that the sudden emergence of human cases of H7N9 in Wenshan in was due to exposure to imported live poultry at LPMs, indicating that hygienic management of LPMs and virological screening of chickens transported across regions should be reinforced to limit the spread of H7N9 virus.
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