Avian Influenza

(Bird flu)

Avian influenza is caused by Influenza A strains that normally infect only birds and wild domesticated fowl (and sometimes pigs). Recently, human infections have been discovered that were caused by these strains.

Most cases of avian influenza in humans have been caused by the avian influenza strains A H5N1 and more recently by strain A H7N9, but the strains H7N7, H7N3, H9N2 and H10N8 also led to several human infections. Infection with these strains lost in wild birds usually asymptomatic, but can lead to a disease with very high mortality in poultry.

Avian influenza is caused by Influenza A strains that normally infect only birds and wild domesticated fowl (and sometimes pigs). Recently, human infections have been discovered that were caused by these strains. Most cases of avian influenza in humans have been caused by the avian influenza strains A H5N1 and more recently by strain A H7N9, but the strains H7N7, H7N3, H9N2 and H10N8 also led to several human infections. Infection with these strains lost in wild birds usually asymptomatic, but can lead to a disease with very high mortality in poultry. The first human cases of H5N1 were discovered in Hong Kong 1997th Further spread to humans could be prevented by the slaughter of poultry stocks. 2003 and 2004, however, occurred in H5N1 infections in humans and there continue to be reports of occasional cases, particularly in Asia and the Middle East. Human infection with other avian influenza strains were also in Asia (H9N2), Canada (H7N3), the Netherlands (H7N7) and China (H10N8) reported. At the end of 2013, the first two human cases of avian H10N8 influenza were diagnosed in southeast China. One patient, an elderly woman with a weakened immune system, died. All their contacts were asymptomatic. Although most cases of avian influenza have been caused by exposure to infected birds, there were probably some transfers from person to person in the Netherlands and in Asia. In early 2013 there was a widespread outbreak of avian H7N9 influenza in several provinces in southeast China. About a third of the cases was fatal, but a significant illness occurred usually only in the elderly. Sustainable human-to-human transmission did not occur, although there is some evidence of limited human-to-human transmission. The human infection appeared from a direct contact with infected birds to poultry markets in live animals (wet markets) in which birds are bought for the subsequent consumption at home, to result. The outbreak came in late spring 2013 to its peak, then lay down (in part because the markets were closed), but then returned in early autumn. The effect of this outbreak is not yet clear. So far, he is, however, confined to the south of China. It is likely that avian influenza viruses of any antigen specificity influenza can cause in humans if the virus acquires mutations through which it can bind to specific receptors in the airways of humans. Because all influenza viruses to be able to change rapidly genetically, there is a probability that avian strains can acquire the ability to more easily from person to person through direct mutation or a rearrangement of genome subunits with human strains during replication in to be transferred to a human, animal or avian host. Many experts are concerned that it could lead to an influenza pandemic if these strains acquire the capacity for easy transmission from human to human. Human infections with avian H5N1 influenza strains can cause severe respiratory symptoms. The mortality was at the outbreak of 1997 33% and> 60% in the subsequent infections. Infection with H7 strains usually leads to conjunctivitis, although some patients in the outbreak in the Netherlands had influenza-like symptoms and one patient died (of 83). Diagnostic reverse transcriptase PCR (RT-PCR) This infection should be considered when clinical after exposure to a known infected person or, in an area with ongoing outbreaks of avian influenza, after exposure to birds in a patient to characteristic complaints come. A positive history of travel to areas with ongoing transmission of the virus from domestic fowl to humans (eg. As for H5N1 Egypt, Indonesia and Vietnam) as well as exposure to birds or infected humans requires immediate testing for influenza A by RT-PCR. A cultural virus isolation should not be sought. Suspected and confirmed cases to the CDC (n. D. Übers .: to the competent health authority) reported. Therapy A neuraminidase inhibitor is indicated, treatment with oseltamivir or zanamivir in the usual dosage. The H5N1 virus is resistant to amantadine and rimantadine; of resistance to oseltamivir has also been reported.

Health Life Media Team

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