H5N1 Influenza A

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Etiology/Bacteriology

Taxonomy

| Domain = Viruses
| Class = ssRNA viruses
| Order = ssRNA negative strand viruses
| Family = Orthomyxoviridae
| Genus = Influenzavirus A
| species = Influenza A virus

NCBI: [1] Genome: Influenza A Virus H5N1 [2]

Description

Avian Influenza A (H5N1) is a type of influenza virus responsible for causing severe respiratory disease in birds, generally waterfowl and humans. However, researchers have yet to definitively document human-to-human transmission and victims of avian-to-human transmission generally spend substantial amounts of time around birds (like poultry farm workers, migratory duck herders, etc.) There is a growing amount of concern about the virus because of its high mortality rate and its disposition to mutation, which renders the human adaptive immune response fairly limited and the virus would be devastating if it were to mutate to a strain capable of human-to-human transmission. Symptoms of infection include high fever (>38°C), malaise, cough, sore throat, muscle aches, abdominal or chest pain, and diarrhea. The sequelae of H5N1 infection are often severe respiratory illness including pneumonia and acute respiratory distress syndrome as well as neurological changes like altered mental state and seizures. Treatment often involves implementation of the antiviral medication oseltamivir. At this stage, all vaccinations are still experimental (3).

Pathogenesis

Transmission

Transmission of H5N1 primarily occurs via direct avian-to-human contact. Major risk factors include handling diseased poultry and the consumption of raw or undercooked poultry products. The exact mode and sites of infection in the respiratory tract remain unknown. H5N1 also has several mammalian hosts including cats, dogs, and ferrets. None have been shown to transmit the disease to humans. However, a genetically modified strain of the virus was capable of airborne transmission in ferrets, which gives insight into the possibility of human-to-human transmission (4). The mode of transmission remains unclear for about one quarter of infected patients and environment-to-human transmission has not been ruled out. It is still uncertain whether infection can begin in the gastrointestinal tract, but it has been implicated in other mammals and is an open area of research.

References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Created by {Marrett Hild}, students of Tyrrell Conway at the University of Oklahoma.