Avian Influenza: Human Pandemic Concerns (original) (raw)

Highly pathogenic H5N1 avian influenza virus: Cause of the next pandemic?

Comparative Immunology, Microbiology and Infectious Diseases, 2009

Since 1997, when human infections with a highly pathogenic (HP) avian influenza A virus (AIV) subtype H5N1 -previously infecting only birds -were identified in a Hong Kong outbreak, global attention has focused on the potential for this virus to cause the next pandemic. From December 2003, an unprecedented H5N1 epizootic in poultry and migrating wild birds has spread across Asia and into Europe, the Middle East, and Africa. Humans in close contact with sick poultry and on rare occasion with other infected humans, have become infected. As of early March 2007, 12 countries have reported 167 deaths among 277 laboratory-confirmed human infections to WHO. WHO has declared the world to be in Phase 3 of a Pandemic Alert Period. This paper reviews the evolution of HP AIV H5N1, molecular changes that enable AIVs to infect and replicate in human cells and spread efficiently from person-to-person, and strategies to prevent the emergence of a pandemic virus. #

Avian and Pandemic Influenza Threats: the Current Situation

Procedia in Vaccinology, 2010

Pandemic, zoonotic and seasonal influenza viruses remain a threat to humans, and have major health and economic impacts globally. The pandemic threat due to Influenza A (H5N1) still exists since the virus is still endemic in poultry population in some countries. Sporadic cases of influenza A (H5N1) in humans are regularly reported. Efforts made by the animal sector to reduce circulation in poultry have contributed in reducing the risk of human H5N1 infection in many parts of the world. On 25 April 2009, Mexico, under the International Health Regulations (2005), notified the World Health Organization (WHO) about an outbreak of new influenza virus, which was characterized as a H1N1 virus previously not found in human. In less than nine weeks, the pandemic virus spread in the six WHO regions. On 11 June 2009, WHO announced a phase 6 pandemic alert. Thanks to the preparedness efforts carried out in a large number of countries in the world in response to influenza A (H5N1) threats, the international community has responded quite well to the pandemic. In particular, countries have been especially collaborative regarding the exchange of information and the global approach of access to supplies such as vaccine and antiviral drugs. The current pandemic presents significant differences to seasonal influenza epidemics and specific challenges are identified.

The emergence of pandemic influenza viruses

2010

Pandemic influenza has posed an increasing threat to public health worldwide in the last decade. In the 20th century, three human pandemic influenza outbreaks occurred in 1918, 1957 and 1968, causing significant mortality. A number of hypotheses have been proposed for the emergence and development of pandemic viruses, including direct introduction into humans from an avian origin and reassortment between avian and previously circulating human viruses, either directly in humans or via an intermediate mammalian host. However, the evolutionary history of the pandemic viruses has been controversial, largely due to the lack of background genetic information and rigorous phylogenetic analyses. The pandemic that emerged in early April 2009 in North America provides a unique opportunity to investigate its emergence and development both in human and animal aspects. Recent genetic analyses of data accumulated through long-term influenza surveillance provided insights into the emergence of this novel pandemic virus. In this review, we summarise the recent literature that describes the evolutionary pathway of the pandemic viruses. We also discuss the implications of these findings on the early detection and control of future pandemics.

Avian Influenza Virus Tropism in Humans

A pandemic happens when a novel influenza A virus is able to infect and transmit efficiently to a new, distinct host species. Although the exact timing of pandemics is uncertain, it is known that both viral and host factors play a role in their emergence. Species-specific interactions between the virus and the host cell determine the virus tropism. These include binding and entering cells, replicating the viral RNA genome within the host cell nucleus, assembling, maturing, and releasing the virus to neighbouring cells, tissues, or organs before transmitting it between individuals. Influenza has a vast and antigenically varied reservoir. In wild aquatic birds, the infection is typically asymptomatic. Avian influenza virus (AIV) can cross into new species, and occasionally, it can acquire the ability to transmit from human to human. A pandemic might occur if a new influenza virus acquires enough adaptive mutations to maintain transmission between people. This review highlights the key...

Pandemic potential of highly pathogenic avian influenza clade 2.3.4.4 A(H5) viruses

Reviews in Medical Virology, 2020

The panzootic caused by A/goose/Guangdong/1/96-lineage highly pathogenic avian influenza (HPAI) A(H5) viruses has occurred in multiple waves since 1996. From 2013 onwards, clade 2.3.4.4 viruses of subtypes A(H5N2), A(H5N6), and A(H5N8) emerged to cause panzootic waves of unprecedented magnitude among avian species accompanied by severe losses to the poultry industry around the world. Clade 2.3.4.4 A(H5) viruses have expanded in distinct geographical and evolutionary pathways likely via long distance migratory bird dispersal onto several continents and by poultry trade among neighboring countries. Coupled with regional circulation, the viruses have evolved further by reassorting with local viruses. As of February 2019, there have been 23 cases of humans infected with clade 2.3.4.4 H5N6 viruses, 16 (70%) of which had fatal outcomes. To date, no HPAI A(H5) virus has caused sustainable human-to-human transmission. However,

Emerging Infectious Disease (1): Avian Influenza

2005

Avian influenza is one of the two terrible virus infections, and the other one is severe acute respiratory syndrome (SARS) in early 21 th century. Studies showed most avian influenza infections of human were directed invaded by the virus (most H5N1 Strain) from poultry but some case reports suspected the possibility of human-to-human transmission. The most frightening possibility is the reassortment of the high pathologic avian influenza with common human influenza virus. If this occurred, a new virus pandemic, like Spanish flu, may come and cause millions of people die. The most important effort is to halt further spread of epidemics in poultry population. Culling the infected and suspected infected poultry widely is needed. It is also essential to have good hand hygiene, have adequate general precaution and educate people to decrease the opportunity for exposure to poultry or their droppings. Health worker have to wear enough precaution in the hospital. The scientists must do their best to develop vaccine against avian influenza as soon as possible.(Ann Disaster