Bird flu - contagious viral disease

Species on earth bed are facing challenges of infectious diseases from time to time.  Bird flu is a contagious viral infection, which can have an effect on all species of birds. Outbreaks of bird flue (avian influenza) have been recognized in poultry flocks in most countries of the world for many years. In modern equipped world, it is a hot topic for laypeople as well as scientist to explore root causes and preventive measure.

Flu has been a usual scourge of humanity for thousands of years. Bird flu is a transmittable disease of birds caused by type A strains of the influenza virus. The virus is well adapted to immune systems to animals, and does not usually make them sick. This leaves the animals free to move around and spread the virus - just what it needs to persist.  Recent cases of anticipative and intrusive risk regulation include the ill-fated attempt to immunize every man, woman, and child in the USA in 1976 against a swine flu epidemic that failed to eventuate (Moore 1995: 110-48), the compulsory slaughter of over a million chickens in Hong Kong in 1997 as a response to a 'bird flu' that was considered to pose a risk of a serious regional or international epidemic, and the UK's ban on beef on the bone in 1997(Robert Baldwin).

History:

The disease, first identified in Italy more than 100 years ago, occurs worldwide. All birds are thought to be susceptible to the avian influenza though some species, such as wild ducks, are more resistant than others. Domestic poultry, such as chickens or turkeys, are particularly susceptible.  Infection triggers a wide spectrum of symptoms in birds, ranging from mild illness to a highly contagious and rapidly fatal disease resulting in severe epidemics. In severe cases, the flu is characterized by a sudden onset of severe illness, and rapid death, with a mortality that can approach 100 percent. (Cnn).

The virus was first isolated from birds (terns) in South Africa in 1961. Avian influenza A (H5N1) was first recognized in 1997 in Hong Kong. Bird flu outbreaks in Asia have prompted the cull of tens of thousands of ducks and chickens to curtail the disease's spread. As the human death toll continues to grow, many are concerned that the virus will mutate and trigger a human pandemic (Nature, UPDATED 25 AUGUST 2004).

In 2003, H7N7 avian influenza affected poultry flocks in the Netherlands, leading to one human death amongst 83 affected people. Culling affected flocks halted the outbreak. H5N1 has recently re-emerged in many Asian countries in slightly altered form. The disease has been confirmed among poultry in Cambodia, China, Hong Kong, Indonesia, Japan, Laos, South Korea, Thailand and Vietnam. Millions of poultry have been slaughtered. The disease has also infected humans in Vietnam and Thailand and deaths have been reported.

The spread of a lethal strain of bird flu in the past two years has sparked fears of a new pandemic. Although more than 200 people have contracted the H5N1 virus, experts point out that cross-infection to humans is still relatively rare, and usually occurs where people have been in close contact with infected birds. Many scientists fear migrating birds to Europe and Africa may carry it but say it is hard to prove a direct link. Others argue that farming methods and human lifestyle could be accelerating the spread (BBC).

15 different types of avian influenza viruses routinely infect birds around the world. H5N1 virus is highly contagious among birds and rapidly fatal. It can be transmitted to humans, causing severe illness and death. Bird Flu is a disease of viral etiology that ranges from a mild or even a symptomatic infection to an acute, fatal disease of chickens, turkeys, guinea fowls, and other avian species, especially migratory waterfowl. The Avian viruses, along with the other influenza viruses, make up the virus family Orthomyxoviridae. The virus particle has an envelope with glycoprotein projections with hemagglutinating and neuraminidase activity. These two surface antigens, hemagglutinin (HA) and neuraminidase (NA), are the basis of describing the serologic identity of the influenza viruses using the letters H and N with the appropriate numbers in the virus designation e.g., H7N2.

The main carriers of this virus are Wild waterfowl. They can be responsible for the prime introduction of infection into domestic poultry. When avian influenza spreads to poultry or other birds, it can cause more severe diseases. Among domestic poultry species, turkeys are more commonly infected than chickens. All birds are thought to be susceptible to infection with avian influenza, though some species are more resistant to infection. If the disease is severe, it can only be eradicated by slaughtering all birds in affected flocks.

In most cases, it has been observed that people suffer from bird flu will recover in one to two weeks, but some people will develop life-threatening complications (such as pneumonia). Elderly People, people with chronic medical conditions, and very young children are more likely to get complications such as Pneumonia, bronchitis, and sinus and ear infections from bird flu.

Waterfowl act as a reservoir of avian influenza virus by carrying the virus in their intestinal tract and shedding it in their faeces. Avian influenza viruses are spread to susceptible birds through inhalation of influenza particles in nasal and respiratory secretions and from contact with the faeces of infected birds.

A person can spread the flu starting one day before he or she feels sick. Adults can continue to pass the flu virus to others for another three to seven days after symptoms start. Children can pass the virus for longer than seven days. Symptoms start one to four days after the virus enters the body. The incubation period is usually 3 to 7 days.

The symptoms can vary from a mild disease with little or no mortality to a highly fatal, rapidly spreading epidemic (highly pathogenic avian influenza) depending on the infecting virus strain, host factors, and environmental stressors. It is considered to be a contagious disease and the main way that influenza viruses are spread is from person to person in respiratory droplets of coughs and sneezes. Common symptoms consist of coughing, sneezing, ruffled feathers, swelling of the skin under the eyes, blisters on the combs, swollen heads, nervous signs like depression, and diarrhea. In some cases, birds die rapidly without clinical signs of disease. Client also complaint for fever, headache, tiredness, sore throat,

After getting infection, affected person should drink plenty of liquids, avoid using alcohol and tobacco, and take medication to relieve the symptoms of flu. Antiviral Medications can also be used to prevent the flu. Though virus causes it, so antibiotics (like penicillin) don't work to cure it. The best way to prevent the flu is to get an influenza vaccine (flu shot). Reye syndrome, a rare but serious illness is often observed when children and teenagers who have influenza are taking aspirin.

Wildlife circles have been debating on whether or not wild birds are spreading the virus around the globe. Experts believe they are playing a role but most believe poultry movement, poultry products and poultry manure is the main cause of the spreading of the virus.” But probably not in this case," said Thiermann. "While it's too early to blame the wildlife, it's very likely to be in an area that's remote enough that it's not likely to be associated with international trade.

Statistical data indicates that in 1997, avian influenza A (H5N1) infected both chickens and humans. This was the first time an avian influenza virus had ever been found to transmit directly from birds to humans. During this outbreak, 18 people were hospitalized and 6 of them died. In 2003, two cases of avian influenza A (H5N1) infection occurred among members of a Hong Kong family that had traveled to China. One person recovered, the other died. Since December 2003, 105 people have died from avian flu in nine countries, although the virus has reached birds in 48 countries.

Preventive measure:

The under mentioned preventive and control measures are recommended as per the WHO guidelines (WHO Regional Office for the Western Pacific, Manila, and 26 January 2004):

1. Cullers and transporters should be provided with appropriate personal protective equipment: Protective clothing, preferably coveralls plus an impermeable apron or surgical gowns with long cuffed sleeves plus an impermeable apron. Heavy-duty rubber work gloves may be disinfected. N95 respirator masks are preferred. Standard well-fitted surgical masks should be used if N95 respirators are not available. Rubber or polyurethane boots can be disinfected or protective foot covers that can be discarded.

2. All persons who have been in close contact with the infected animals should wash their hands frequently with soap and water. Cullers and transporters should disinfect their hands after the operation.

3. Environmental clean up should be carried out in areas of culling, using the same protective measures as above.

4. All persons exposed to infected chickens or to farms under suspicion should be under close monitoring by local health authorities.

 It is recommended that oseltamivir be readily available for the treatment of suspected H5N1 respiratory infections in cullers and farm workers involved in the mass culling.

 They should also be vaccinated with the current WHO recommended influenza vaccine to avoid simultaneous infection by human influenza and avian influenza and to minimize the possibility of a re-assortment of the virus's gene. Serological surveillance of exposed animal workers and veterinarians is encouraged.

Scientific view

Scientists fear the bird flu virus could evolve into a form that is easily spread between people, resulting in an extremely contagious and lethal disease. This could happen if someone already infected with the human flu virus catches the bird flu. The two viruses could recombine inside the victim’s body, producing a hybrid that could readily spread from person to person. The resulting virus likely would be something humans have never been exposed to before. With no immune defences, the infection could cause devastating illness, such as occurred in the 1918-19 Spanish flu pandemic, which killed an estimated 40 million to 50 million. Scientists explain migrating birds that flew south to Africa last fall and have now returned to Europe in recent weeks are not carrying the H5N1 flu virus. (Producer: Emily B. Hager)

Italian scientists have found the H5N1 Avian Flu virus, also known as the Bird Flu, in Nigeria. Tests done on samples in a laboratory confirm that the strain is the one that can kill people, although no human cases have been reported said the Paris-based United Nations body. This is the first time is has appeared on the continent.

Reports say tests of the virus closely resemble the virus in Asia. The virus has been discovered in poultry flocks in a large Nigerian farm. "It is the first report of the disease in Africa.

In nutshell, bird flu is a viral infection spread from bird to bird. Humans catch this infection through close contact with birds or bird droppings.