Avian influenza (AI) is classified as an influenza A virus that originates from the birds and causes diseases in domestic and wild mammals including human beings (Su et al., 2015). When it was first detected, the avian influenza outbreak was observed to spread high pathogenic avian influenza virus (HPAIV) strains of subtype H5N1from Asia and caused diseases to human and animals leading to high mortality rates in Southern Countries of Asia including China, India, and Vietnam (Mittal & Medhi, 2007). The diseases caused by avian influenza have been declared endemics in some countries in domestic poultry since it led to slaughter or deaths of more than 250 million birds(Adlhoch et al., 2018). By 2006, the World Health Organization had established a mechanism to prevent, protect, and respond to human health hazards by setting up alert and rapid network actions in the affected regions around the globe. The established response network across the globe is vital for the World Health Organization since it facilitates international communication. The paper discusses the biochemistry of avian influenza and its relation to the current novel coronavirus. In 1997, the risk factors associated with Avian influenza was observed in 15 hospitalized patients in Hong Kong after the death of a child (Su et al., 2015). Human characteristics including age, sex, and locality were assessed concerning exposure to live chicken and it was discovered that the interaction with the birds significantly led to the acquisition of the respiratory disease while food preparation and consumption was insignificant in the spread of the diseases (Mittal & Medhi, 2007). Avian influenza is mainly transmitted to humans by chickens with studies in Hong Kong pointing at manipulation, defeathering, and slaughtering of chicken and geese, and preparation of meat from H5N1 infected birds (Korteweg et al., 2008; Mittal & Medhi, 2007). Though avian influenza is linked to Asian countries, the spread of the disease is rare in human and it predominantly attacks young healthy individuals. The number of cases, however, increased from 2005 with the discovery of new strains of the virus in Europe, Asia, and Africa. The average age of the affected people in the population is 18-year-old youth with 90% of the sick being below the age of 40 (Su et al., 2015). Once an individual is exposed to Avian influenza, the incubation period varies from the first day to the seventh day but may extend up to 9 days in some patients. The mortality rate of the disease caused by Avian influenza is 61% which is quite high compared to an average of 2% of the coronavirus.
A vital characteristic of avian influenza viruses is the composition of the PB1, PB2, and PA which defines the genetic determinants of the host range that principally mutate in the viral polymerase (Tran et al., 2018). The viral polymerase accumulates into viral ribonucleoprotein (vRNP) complexes and another pathological genome RNA(vRNA) in addition to a nucleoprotein (NP) that aids in the transmission of viral transcription and genome replication (Tran et al., 2018). PB1 functions as a polymerase catalyst for the replication of nucleotides in the synthesized RNA. After the bonding of the viral polymerase on the cellular RNA polymerase, PB2 notices the new formations of polymerase 2, which leads to cleavage of pre-m-RNAs on PA endonuclease that aid in viral transcription. Though scientists have not divulged further details of the breakdown in the body, the viral genome replication is independent since it generates mature vRNA and cRNA that are fully complementary to copies of vRNA (Korteweg et al., 2008). The process can be compared to the adaptive nature of the mutation and substitution of amino acids position 627 from the bird's signature glue to the human signature. In extremely fatal cases of the flu in humans, PB2 627K has been detected in people with avian influenza, a factor that increases polymerases activity and viral pathogens in mammals (Tran et al., 2018). One infected with the avian flu, multiple mutations occur in the body in the viral polymerase subunits like the F35L and T97I, contained in the PA protein and play an important role in host range determinants of avian influenza. Multiple replications of the H5N1 virus in the human body lead to damages of the cells and organs through cytolytic processes, which are similar to other human influenza diseases (Tran et al., 2018). Avian influenza is characterized by active viral replication in the respiratory tract. However, there is little evidence to show infections in the throat, trachea, and lung tissues. In tests undertaken from avian influenza patients, viral RNA was detected in nasal, nasopharyngeal, and tracheal specimens from day one to the fifteenth day (Su et al., 2015). The viral replication of H5N1 appears to take a long time because a study of the viral load versus time did not show a decline. Under the category of H5N1 cases, the viral RNA levels in pharyngeal and nasal tests were high compared to patients with common influenza diseases (Mittal & Medhi, 2007). Studies have suggested that there is a high viral load in fatal cases indicating the association between viral replication and negative outcomes of avian influenza (Korteweg et al., 2008; Su et al., 2015; Tran et al., 2018). The laboratory diagnosis of H5N1 is undertaken from nasopharyngeal aspirate that is extracted three days after the manifestations of symptoms. According to Korteweg et al. (2008), the specimen undergoes antigen assays, virus culture, and real-time polymerase chain reaction (RT-PCR) for the detection of the various.
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The World Health Organization established procedures that were vital in preventing the spread of avian influenza among people who were highly exposed. Just like the coronavirus, the people at high risk of acquiring avian influenza were advised to wear protective clothing, surgical masks, goggles, and rubber boots (Adlhoch et al., 2019). Upon testing positive for avian influenza, the antivirals must be prescribed for confirmed cases. Additionally, vaccination is recommended for individuals who are highly exposed to H5N1 like healthcare workers. Currently, there are two groups of drugs available for the treatment of the virus, which include the adamantanes and the neuraminidase inhibitors (Su et al., 2015). The adamantanes are prescribed in two formats: the amantadine, and rimantadine and work by interfering with the viral uncoating inside the cell. The adamantanes are an effective drug for treatment avian influenza though it is associated with some toxic effects because of some resistant variants. The second drug combination of the drug uses to treat the avian influenza is neuraminidase, which is a combination of zanamivir and oseltamivir (Mittal & Medhi, 2007). The neuraminidase functions in the body of confirmed patients by interfering with the release of progeny influenza virus from infected host cells thus preventing infection of new host cells while halting the spread of infection in the respiratory tract.
The history of finding the cure and treatment of avian influenza started in the 1970s and led to the discovery of sixteen hemagglutinin and nine neuraminidase subtypes (Su et al., 2015). According to Mittal and Medhi (2007), AI viruses are occasionally transmitted to domestic poultry thereby leading to LPAI or HPAI viruses. One of the effective drugs for the treatment of avian influenza is the Oseltamivir, which is consumed in oral formulations (Smith, 2010). Oseltamivir medication has been discovered to reduce mortality rates in an infected patient. It is advised that suspected patients get administered with the drug even before the confirmation of etiology. The strain of the virus that affects humans from the avian influenza H5N1 is associated with higher levels and sustained viral replication. When administered in higher doses of 150mg twice daily for a period of 8 to 10 days, oseltamivir will control viral replication and lead to better patient outcomes (Smith, 2010). The administration of the drug must follow a clinical process and when fever and other conditions persist, bacterial superinfections and nosocomial complications must be examined. Treatment can be extended for a further five days if the conditions of patients do not improve after the standard five days.
Oseltamivir seems to be an effective drug for adults’ ones administered because there is a high rate of absorption in the body. Oseltamivir is taken together with amantadine to reduce viral replication since it enhances the functioning of the antiviral. When either of the drugs is administered alone, the successful outcome of treatment ranges from 50% to 60%, while complete protection is achieved when used together (Tran et al., 2018). Additionally, the combination of the two drugs was effective to counter the resistance caused by the consistent use of oseltamivir (Mittal & Medhi, 2007).
Unlike avian influenza, COVID19 has no known cure and there is no vaccine yet. Currently, the management of the infections from the virus is symptomatic and the use of oxygen therapy for patients with severe symptoms (Cascella M, Rajnik M, 2020). Healthcare systems across the globe implemented the use of mechanical ventilators to aid in oxygen therapy in cases where patients experienced respiratory failure. The World Health Organization recommended a raft of scientific guidelines based on scientific evidence while handling previous pandemics and epidemics. According to Cascella and Rajnik (2020), measures that were used to contain the spread of avian influenza can be used to contain the spread of coronaviruses such as sorting outpatients with severe respiratory illnesses, implementing infection and control measures such as the face mask and social distancing, and early supportive therapy like the antivirals.
The strategies that were used to halt the spread of the coronavirus just like it happened with avian influenza is preventive measures. Vital preventive measures involve isolation of patients and watchful infection control from diagnosis to clinical care of the victims. This entail taking care of the necessary precautions during contact and specimen collection as well as the administration of oseltamivir. Patients infected with avian influenza have been observed to experience almost the same symptoms as COVID-19, influenza, parainfluenza, and rhinovirus. Detection of the disease involves the use of rapid antigen detection and other mechanisms of respiratory pathogen assessment. There is no known cure treatment of COVID-19, however, investigations are rife on the most reliable disease management mechanisms.
References
Adlhoch, C., Fusaro, A., Kuiken, T., Monne, I., Smietanka, K., Staubach, C., Muñoz Guajardo, I., & Baldinelli, F. (2019). Avian influenza overview February– August 2019. EFSA Journal , 17 (9), 4–23.
Adlhoch, C., Kuiken, T., Mulatti, P., Smietanka, K., Staubach, C., Muñoz Guajardo, I., Amato, L., & Baldinelli, F. (2018). Avian influenza overview May – August 2018. EFSA Journal , 16 (9), 3–12.
Cascella M, Rajnik M, C. A. (2020). Features, evaluation and treatment coronavirus (COVID-19). StatPearls Publishing . https://www.ncbi.nlm.nih.gov/books/NBK554776/
Korteweg, C., Gu, J., & Ph, D. (2008). Pathology , molecular biology , and pathogenesis of avian influenza A (H5N1) infection in humans. The American Journal of Pathology , 172 (5), 1155–1170.
Mittal, N., & Medhi, B. (2007). The bird flu: A new emerging pandemic threat and its pharmacological intervention. International Journal of Health Sciences , 1 (2), 277–283.
Smith, J. R. (2010). Oseltamivir in human avian influenza infection. Journal of Antimicrobial Chemotherapy , 65 (2), 25–33.
Su, S., Bi, Y., Wong, G., Gray, G. C., Gao, G. F., & Li, S. (2015). Epidemiology, evolution, and recent outbreaks of avian influenza virus in China. Journal of Virology , 89 (17), 8671–8676.
Tran, P., Pham, V., Turan, K., Nagata, K., & Kawaguchi, A. (2018). Biochemical characterization of avian influenza viral polymerase containing PA or PB2 subunit from human influenza A virus. Microbes and Infection , 3–15.
