What is Avian Influenza (Bird Flu)?
Avian influenza, often called bird flu, is an especially deadly virus. It’s important for healthcare workers to understand the severe nature of this disease, as it may require more precautions and early intervention. Avian influenza is a term covering various strains of the influenza A virus that typically infects birds but can sometimes cause illness in humans as well. Notable outbreaks of bird flu have occurred in the past, such as the H5N1 outbreak in 1997 in Hong Kong, and the H7N9 outbreak in China in 2013.
Despite originally being found in birds and usually leading to mild illness, avian influenza can severely affect humans. A lot of confirmed cases need hospital care and often intensive care unit (ICU) treatment. This flu is part of the Orthomyxoviridae family, sharing this group with different types of flu viruses. However, only influenza A has been found in birds.
There’s a lot we still don’t know about how the virus spreads from bird to bird. It’s known to be released in large numbers through bird feces and respiratory matter. The types of avian influenza include the highly pathogenic avian influenza (HPAI) and the low pathogenicity avian influenza (LPAI), with the former more commonly leading to deadly outbreaks in humans despite being less common in birds.
To identify different types of Flu A virus, scientists use combinations of antigens on two surface proteins of the virus, calling them, for example, H5N1. These classifications are critical as the proteins necessary to activate these strains are found in different parts of the host body depending on the virus type.
While bird flu is found in most bird types, both wild and domestic, it’s usually domestic birds that cause human disease outbreaks due to more frequent contact. Some diseases may, however, spread via migratory birds that carry the virus to new locations, infecting domestic birds, and subsequently humans. Most commonly, bird flu is transmitted to humans through direct contact with live birds or handling raw poultry in places like factories and restaurants.
What Causes Avian Influenza (Bird Flu)?
Bird flu viruses can infect humans when a type of the virus becomes capable of affecting a human host. This can occur either by mixing with flu viruses from other species or by slight genetic changes, or sometimes both. High pathogenic avian influenza (HPAI) strains of the virus are believed to be activated in most host body systems, while low pathogenic avian influenza (LPAI) strains get activated in certain organs with specific enzyme modifications. This difference may be the reason for some specific symptoms and signs associated with certain strains of the virus.
Risk Factors and Frequency for Avian Influenza (Bird Flu)
Avian influenza viruses (AIVs), such as H5N1 and H7N9, are known for infecting humans. While it’s possible other AIV strains have infected humans, these two strains are most common. So far, there have been no confirmed human cases of AIV infection in the United States, but there has been one confirmed death in Canada. H5N1 outbreaks are frequently reported in the Middle East and Southeast Asia, with occasional cases in West Africa. H7N9 outbreaks mainly occur in the same areas. People who are often in close contact with poultry, especially recently slaughtered birds, are more likely to get infected with AIV.
- In China, H7N9 infection seems more common in older people and H5N1 in younger ones.
- Both strains seem to affect men more than women.
Even though other AIVs can infrequently infect humans, H5N1 and H7N9 are the most common and currently, the others seem to be sporadic at best.
Signs and Symptoms of Avian Influenza (Bird Flu)
Avian influenza, commonly known as bird flu, can produce a variety of symptoms, but these are often only observed in patients who become so ill they require hospital treatment. This is because testing for bird flu isn’t typically done unless a patient has severe symptoms. Consequently, there isn’t much information available on what milder cases of the infection might look like. Generally, symptoms emerge between 2 to 4 days following exposure to the virus, but in some instances, they might only begin over a week later.
Patients usually show symptoms similar to those of a standard flu-like illness. If there’s a known outbreak of bird flu in the area, and these patients have a history of contact with birds, especially those who work in poultry or culinary industries, they should be considered as potential bird flu cases. It’s noteworthy to mention that most bird flu patients have had contact with poultry, although there are confirmed cases where the virus has passed from the environment to humans, or even from one human to another.
- Flu-like illness
- Contact with birds
Different strains of bird flu can lead to different symptoms. For instance, the H5N1 strain typically results in fever and respiratory problems, along with occasional, early-stage, non-bloody and non-inflammatory diarrhea. The H7N9 strain and other lower pathogenic avian influenza viruses may be more commonly accompanied by an eye inflammation referred to as conjunctivitis. However, if there’s an ongoing bird flu outbreak in the area, it’s most likely that a patient presenting with the illness has the same strain as other infected patients in the area.
- H5N1: Fever, respiratory problems, occasional diarrhea
- H7N9: Commonly associated with conjunctivitis
Testing for Avian Influenza (Bird Flu)
Diagnosing bird flu, or avian influenza, needs a keen eye from your doctor. If you have flu-like symptoms and have been recently handling live birds or have been involved in poultry farming, your doctor may suspect bird flu. Along with your symptoms, your doctor will run additional tests to check for any harmful effects of the bird flu virus, such as breathing difficulties and other organ problems. Since bird flu can cause serious breathing problems, your doctor will closely monitor your breathing. Depending on how severe your condition is, your treatment may involve additional oxygen, a breathing machine, or even a procedure called ECMO (which uses a machine to add oxygen to your blood and remove carbon dioxide) for the most severe cases.
While there’s a rapid test that can check for the bird flu virus, it often gives a negative result even if you truly have the disease. The best way to take a sample for this test is by using a swab to take a sample from the back of your nose and throat. If this isn’t possible, other body fluids can be used for testing. It’s important to note that even if your rapid test comes back negative, your doctor may still suspect bird flu if you have strong symptoms and risk factors. The gold standard for confirming bird flu is a more in-depth test known as RT-PCR, which can typically detect the virus a few days after symptoms start.
Treatment Options for Avian Influenza (Bird Flu)
The treatment of bird flu primarily involves taking care of the patient’s symptoms and giving them antiviral medications. Care generally focuses on treating the consequences of the infection. For example, patients who’ve lost fluid or have an imbalance in their body’s chemicals should receive fluids and treatments to correct the imbalance. If a patient has a fever, they should be given medicine to reduce it. Patients who have breathing difficulties should be given extra oxygen and monitored closely as they may need to be put on a breathing machine. Since severe bird flu can cause different organs to not work properly or even fail, doctors need to closely watch for these signs and treat them quickly to avoid the patient’s condition worsening.
The World Health Organization (WHO) provided guidelines in 2007 for treating outbreaks of a specific bird flu strain called H5N1. These suggestions could likely be used for bird flu caused by other virus strains too. The guidelines recommend using neuraminidase inhibitors, particularly one called oseltamivir, for people who likely or definitely have H5N1. They also suggest not to use M2 ion channel inhibitors like amantadine and rimantadine as the only treatment, unless neuraminidase inhibitors aren’t available or the virus doesn’t respond to them.
The WHO also suggested using preventative treatment for those who might have been exposed to the virus. Specifically, they strongly recommend oseltamivir (75 mg daily) for 7 to 10 days after the last possible exposure in people who are at high risk, such as those who live with or are close family contacts. People at moderate and low risk are not as strongly recommended to receive preventative treatment, although those at moderate risk need individual evaluation.
What else can Avian Influenza (Bird Flu) be?
When diagnosing bird flu, doctors have to consider a range of other illnesses because it can have similar symptoms to many different conditions. For example, if a patient comes in with a headache with or without fever, doctors would consider if it could be due to problems like meningitis (an infection within the brain or spinal cord), a brain bleed, migraines, or other conditions that cause headaches.
For individuals with breathing challenges due to bird flu, other illnesses affecting the upper and lower part of the respiratory tract could be mistaken for the disease. The symptoms could be due to:
- Pneumonia caused by bacteria
- Strep throat (a bacterial infection in the throat and tonsils)
- Asthma (a chronic condition that affects the airways in the lungs)
- Chronic obstructive pulmonary disease (COPD; a type of lung disease)
- Pulmonary embolism (a blood clot in the lung)
Lastly, if the patient is experiencing shortness of breath or other signs that could involve the heart, the doctor would also consider if the symptoms could be due to issues like pericarditis (an inflammation of the lining around the heart) or myocarditis (an inflammation of the heart muscle).
What to expect with Avian Influenza (Bird Flu)
For those needing hospital care due to avian flu, the death rate is reported to be over 50% across all strains of the avian influenza virus. However, when we look closer, it appears that the H7N9 strain leads to a 35% death rate, while the H5N1 strain results in a higher mortality rate of 60%.
It’s important to note that not all people affected by the avian flu may end up in a hospital. Many might have milder symptoms and a lower risk of mortality. Despite this, the avian flu is harmful to humans, and those needing hospitalization generally have a poor outlook.
Possible Complications When Diagnosed with Avian Influenza (Bird Flu)
Complications from bird flu (avian influenza virus or AIV) can arise from multiple sources. These can include damage or failure of organs, accidental harm during treatment, or getting another infection at the same time. Because severe disease and widespread organ failure are quite common with bird flu, it is expected that there could be long term complications. People who require lots of mechanical ventilation assistance might experience long term breathing difficulties. And those who have a sudden kidney issue from AIV might develop chronic kidney disease. It’s also possible to get a bacterial infection at the same time as the viral illness, so this should be considered if a patient’s condition changes during the illness or if their condition gets worse after seeming to improve.
Preventing Avian Influenza (Bird Flu)
When there might be an outbreak of bird flu, one of the best ways to lessen the illness’ impact on people’s lives is by reducing the virus’s spread. As it doesn’t spread from person to person frequently, we should concentrate on promoting good hygiene practices, particularly among those who work with birds or in food preparation.
Once we recognize an outbreak, public health officials play a key role in identifying people who could be at a higher risk. They also help the public understand the risk factors, how to spot possible infections, and how to act if they suspect an infection. Given that the possibility of deadly diseases can spark fear and panic in the community, it’s essential to reassure those who are at a minimal risk of contracting the bird flu.
People who work with birds, either alive or dead – including those involved in preparing poultry in restaurants – should be well-informed about the symptoms of bird flu. They should know how and when to reach out to health officials, and what steps to follow if they suspect they might be infected.
