H5N1 Avian Influenza is Spreading and Affecting Selected Fauna

Avian influenza, avian (bird) and influenza (flu) also known as Bird flu is a form of influenza caused by a virus found in birds. 

It is similar to variants found in animals and humans caused strains which have over time adapted to specific hosts. 

OVERVIEW OF AVIAN INFLUENZA

Three types of influenza viruses exist, labelled A, B and C. The A variant is noticed in birds and is commonly referred to as Avian influenza. Influenza A viruses are part of the Orthomyxoviridae. Influenza B and C have been found in other species, only A is known to infect birds. The mechanism of how one bird is infected from one bird to another is not well known as of now. 

The avian viruses occur in both domestic and wild bird species. Domestic birds are held more responsible for disease outbreaks in humans as humans are more exposed to them. Migratory birds also carry diseases to different locations, subsequently infecting domestic birds, followed by human transmission. 

Recent research has confirmed that it was adapted from both human and avian strains. The avian strains are also divided according to their pathogenicity, which can be both high (HP) and low (LP). The LP strains are comparatively more common and cause a few diseases only. But, in humans both LP and HP strains can bring disastrous influenza outbreaks. Among the two, HP strains occur more frequently. 

The potential of a microbe to cause damage in host organisms is Pathogenicity. On the other hand, Virulence is the degree of damage caused by the microbe. The most well-known strain is H5N1, which was first isolated from a farm goose in China, in the year 1996. It was between 2013 and 2017 that 916 laboratories confirmed human cases of strain H7N9. These were reported to the world health organization (WHO). 

SUBTYPES OF AVIAN INFLUENZA

Many subtypes of avian influenza viruses exist, but only the following have been known to infect human beings, 

• H5N1
• H7N3 
• H797
• H9N2
• H10N8 
• H10N3

TRANSMISSION

While most avian influenza is not zoonotic( they do not spread from animals to humans), some strains such as H5N1 can infect humans. Bird-to-human infection has been observed to be the result of handling infected poultry birds. Not just that, contaminated surfaces are also a source of infections. 

The low hygienic conditions and close quarters make H5N1 the largest threat in the Asian continent. Infection from the bird to humans happens relatively easier as compared to human-to-human transmission. 

All viruses mutate over time- particularly influenza viruses. Since the viruses move amongst and between both human and animal populations, viral mutation can and does occur. This is why surveillance is crucial. 

BIRD FLU SYMPTOMS

The symptoms of Bird flu may vary from person to person but generally, they are similar to typical flu symptoms. They include, 

• Fever of 100 degrees Fahrenheit or higher 
• Body ache 
• Cough 
• Sore throat
• Nausea and vomiting
• Diarrhoea
• Conjunctivitis

It may also cause severe respiratory symptoms and conditions like, 

• Pneumonia
• Respiratory distress
• Breathing disorders 

Infection with Bird flu may also cause bacterial infections in patients. If the bird infection gets severe, the patient might develop neurological signs and symptoms like seizures. There’s also a possibility of the flu causing multiple failure organs and a septic shock. 

The diagnosis of avian flu cannot be done  by symptoms alone. Specialized testing is done to arrive at the result. 

TREATMENT

The flu is treated with medicines that target the virus ruthlessly, the antiviral medications.  The most common treatments of the same involve, 

Oseltamivir, Peramivir and Zanamivir 

PREVENTION

Residents and travelers must avoid, 

• Poultry farms 
• Getting in contact with animals in poultry markets 
• Entering areas of animal flesh 
• Touching or contact of any kind with surfaces that might be contaminated with faeces of poultry
• Consumption of raw or partially cooked meat or eggs 

Along with this, people must adopt best hygiene practices. 

VACCINATION

As of now, no vaccination against avian influenza is commercially available. 

The world health organization and its partners are currently working on developing a vaccine that could offer protection from the deadly Bird flu. The commonly available seasonal influenza vaccine does not prevent avian influenza but it reduces the possibility of getting infected with both avian and seasonal influenza, also called dual infection. 

QUARANTINE

When H5N1 is diagnosed on a site, government officials quarantine the site and cull and dispose of all the birds in the infected flock. This is followed by decontamination of the site. A few weeks later, a test is carried out, it must be negative to be deemed infection free. 

GLOBAL HEALTH THREAT 

The strain of H5N1 has spread farther than ever. Scientists are concerned that it might turn out to be a global health threat. It could become the next pandemic if it swiftly spreads from human to human. 

Six simple bio-security steps have been formulated  that will help lower the transmission of avian flu, 

• Keeping a safe distance
• Keeping the surroundings clean 
• Don’t haul diseases home 
• Vigilant on carrying it home from the neighbourhood
• Awareness of the warning signs of infections and bird diseases
• Reporting sick bird

These measures will help contain the disease. It will also ensure a secure supply of food. Poultry continues to be safe for consumption however attention should be paid to o its preparation. 

PANDEMIC POTENTIAL

In recent years, A rise has been noticed in the number of avian influenza cases.  The H5N1 strain holds a 50% mortality rate and has become a matter of concern for the public authorities. The mortality rate is higher than other viruses that caused recent flu pandemics. At this point, the risk of avian influenza causing a pandemic is very low.