Containing and Eradicating a Pandemic - Coursework Example

Containing and Eradicating a Pandemic Containing and Eradicating a Pandemic Yee et al. (2009) find that H5N1 avian influenza (A1) infection associates with direct contact with infected poultry. Avian Influenza Viruses envelope in a single stranded negative sense belongs to the Orthomyxovindae family. The virus has eight different RNA segments that have high susceptibility of mutation. The AIVs exchange RNA segments in the nucleocapsid and lysed from a cell to transform to a new virus. Type A influenza is highly pathogenic in humans and poultry to infect a wide range of hosts. The subtype of characterization of AIV includes hem agglutinin (HA) and neuraminidase (NA) glycoprotein located on the outer surface of the envelope. Yee et al. (2009) identify sixteen HA and nine NA subtypes. Low pathogenic AIVs cause respiratory diseases and low mortality in birds. High pathogenic viruses cause systematic disease that lead in turkeys and chickens. The origin of AIV began in 1990s in Hong Kong and recently spread beyond Asia, Europe, and Africa. Researchers were able to isolate some sick birds in Guangdong Province in China in 1996. In 1997, a boy from Hong Kong was infected with H5N1. He later succumbed to respiratory failure. At the end of 1997, the death toll of H5N1 victims in Hong Kong claimed 18 human lives and all live birds market. Researchers associate the death of H5N1 victims to the infected birds since upon the closure and depopulation of LBMs, human death ceased. The early epidemic investigations associate human cases and the exposure of LBM system in Hong Kong. The HA from human cases and subsequent H5N1 outbreaks in Asia genetically relate to the issue of birds in Guangdong. The lineage of the 2003-2006 H5N1 epidemic roots genetically from isolates in 1997. H5N1 HPAI continues to spread across Asian countries such as China, Vietnam, and Hong Kong in domestic and wild birds. Human cases H5N1 resurfaces in Vietnam in 2003 that began another epidemic in Southeast Asia with sporadic cases in Europe, Africa, and Middle East. Currently, there is a global concern on the possibility of a outbreak of AVI influenza isolated human case HPAIV H5N1 continue in several Asian countries, and this could mutate to a form spreading rapidly to humans. Most of the human cases have a history of very close contact with infected poultry .inhalation of infectious droplets is the most common route of infection as Most of the human cases history Since October 2003, there has been 60percent case-fatality rate with most of the documented cases human cases dying (Lenes et al. 2010). In addition to humans, birds, fowls, and poultry died from the AVIs scourge. Some of the host infected host species for H5N1 expands to canines, swine, wild birds, and mustelidae. The far-reaching effect of H5N1 adversely affects domestic bird, poultry industry, and human population health. In April 2009, a global outbreak of A H1N1 virus started in Mexico. The swine flu virus generated by multiple re assortment of events in pigs and people that led to contamination of other human beings. The World Health Organization declared AVIs as a pandemic in June 2009. The evaluation of isolates collected from surveillance in Hong Kong and Mainland China conclude that LBMs provide an environment for AIVs. Birds sold in the LBM system are highly susceptible to for transmission of disease as they have a high rate of co-mingling with other different species from different flocks. The poultry to human transmission of H5N1 associates with direct contact of the sick poultry. () report that exposure or contact with dead or sick birds in the house, indoor water source, and neighborhood. LBMs or live animal markets pose a risk for AI infection. Another mode of transmission for the spread of H5N1 is in the illegal trade and transport of sick birds. A country with high demand of poultry during the era of the pandemic could have a high H5N1 transmission. Vietnam authorizes claim that most of their poultry was through illegal transportation from China. The poultry cases in Thailand largely associates with rice paddy fields and free-grazing ducks in the area. The authors suggest that infection of domestic poultry is due to co-mingling of wild waterfowl and domestic ducks that arise due to agricultural practice. Dead poultry in Europe is a situation preceded by H5N1 poultry cases. Most isolations of H5N1 emanates from dead or sick world birds. Shim & Galvani (2009) believes that since 2003 there has been a significant concern concerning the possibility of A (H1N1) a subtype of H5N1. The pandemic of novel swine-origin influenza already claims thousand of human deaths and illnesses. The virus contaminates the water resources through wild birds’ excreta and sewerage systems. Wild birds constitute the natural reservoir for all AIVs that cause asymptomatic or low pathogenic infection. The viruses replicate in the respiratory and in the gastro-intestinal tract in ducks. Researchers have recently detected AIV in water bodies where waterfowl gather for replenishment. The viruses can persist for a longtime in water that varies among AIV isolates and water attributes such as salinity, temperature, and PH. The potential considerations of AIV surface water using quantitative microbial risk, oral ingestion, or aspiration of contaminated water. The surface water resources and groundwater aquifers under the influence of surface water is a potential route for H5N1 virus to enter drinking water supply. Shim & Galvani (2009) cite that to decrease the threat of H5N1 influenza virus transmission, one has to place ready control policies in place. The objective of the control policy is to reduce the average number of infections produced by an infected individual in a susceptible population. Lenes et al. (2010) speaks of mass culling of avian hosts as a long-standing practice for influenza control within the avian reservoir. The culling of more than 100 million chicks took place in Asia to contain H5N1 between 2004 and 2005. The economic impact of H5N1 and associated culling exceeded 22 billion dollars. Culling is a successful plan to control the emergence of H5N1 outbreak. The subsequent virus surveillance shows that control measures such as culling and vaccination are effective upon implementation. Lenes et al. (2010) evaluates the evolutionary repercussion of mass avian culling as a vital strategy and epidemiological beneficial to reduce long-term resistance to H5N1, increase host mortality, and select elevated influenza virulence. According to Shim & Galvani (2009), culling reduces the average duration of infection and influenza to decrease the resistance of the threshold. The author’s analysis illustrates culling as sufficient rapid to eliminate the influenza without selecting the host resistance. The author’s finding indicate that a mass culling six times the rate of background avian mortality is sufficient to drive the influenza below 1 that result in the termination of the epidemic. The culling policy delays the initial progress of the influenza pandemic with the expectation of having greater mortality. As the rate of culling continues to increase, the resistance evolved reduces. At the cessation of the culling strategy, the population remains vulnerable to H5N1 reemergence. Vaccination reduces selective pressure that acts on the host resistance to decrease transmission while the impact of the vaccination last longer than the culling policy. Infected countries such as China and Hong Kong implement different control measures with intent of stamping out, restricting, disinfecting, cleaning, and vaccinating poultry. Researchers are yet to come upon one effective control measure to eradicate H5N1. The cleaning and disinfecting premises require the removal of all potential contaminated materials. Improper disposal and handling of the carcass can further spread the disease. References Lénès, D., Deboosere, N., Ménard-Szczebara, F., Jossent, J., Alexandre, V., Machinal, C., & Vialette, M. (2010). Assessment of the removal and inactivation of influenza viruses H5N1 and H1N1 by drinking water treatment. Water Research, 44(8), 2473-2486. Shim, E., & Galvani, A. P. (2009). Evolutionary Repercussions of Avian Culling on Host Resistance and Influenza Virulence. Plos ONE, 4(5), 1-8. Yee, K. S., Carpenter, T. E., & Cardona, C. J. (2009). Epidemiology of H5N1 avian influenza. Comparative Immunology, Microbiology & Infectious Diseases, 32(4), 325-340. Read More