Definition

Avian influenza, or bird flu, is a disease that commonly spreads among birds but can also spread to humans. Infection in humans is usually acquired through direct contact with infected birds or contaminated environments. The avian influenza virus was first discovered in 1997 in Hong Kong and has intermittently infected humans since then, with the most common types found in humans being the H5N1 and H7N9 strains.

Causes

The cause of avian influenza is the influenza A virus, which belongs to the Orthomyxoviridae family. Influenza viruses have four types: A, B, C, D. However, only influenza A viruses can infect birds. This virus is primarily found in ducks, geese, swans, and gulls. The virus causing the disease in birds can infect humans if the virus's genetic material adapts to the human body. Many types of avian influenza viruses have affected humans, causing local and global problems, but the most commonly found are the H5N1 and H7N9 strains. These names are based on the proteins present on the surface of the influenza A virus, namely hemagglutinin (HA) and neuraminidase (NA). There are 18 known subtypes of HA and 11 subtypes of NA, and they can all form different combinations. For example, H5N1 is a strain of avian influenza with HA subtype 5 and NA subtype 1. Almost all influenza A viruses can infect birds, except for H17N10 and H18N11, found in bats.

This virus can be found in bird saliva, mucus, and feces. It then attaches to cells in the eyes, mouth, and respiratory tract, especially the lower respiratory tract. Afterward, the virus can replicate within a certain period, but each type of virus has a different replication period. The human immune system can affect the severity of the disease. For example, pneumonia (lung inflammation) caused by avian influenza can result in damage and bleeding in the alveoli (air sacs in the lungs).

Risk Factor

The main risk factor for avian influenza is exposure to birds or poultry and environments contaminated by bird droppings. Research indicates that H7N9 more frequently affects older individuals, while H5N1 affects younger people. However, both strains affect males more often than females.

Symptoms

Symptoms of avian influenza vary depending on the virus strain. Some strains cause only mild symptoms, while others can lead to severe illness. These symptoms may include red eyes, flu-like symptoms, and sometimes nausea, abdominal pain, diarrhea, vomiting, respiratory problems, neurological issues, and involvement of other organs. Flu-like symptoms can include fever, cough, sore throat, and muscle pain. Respiratory problems caused by avian influenza may include shortness of breath, pneumonia, and respiratory failure. Neurological issues can include decreased consciousness and seizures. H7N9 and H5N1 are the most common causes of avian influenza, including the most severe cases with high mortality rates.

Diagnosis

The signs and symptoms of avian influenza are not specific, so diagnosis requires further testing. Typically, a doctor will suspect avian influenza if there is a history of contact with birds or poultry. Tests that can be performed include nasal and throat swabs, which yield the best results in the first few days. These samples are then taken to a laboratory for genetic material detection using polymerase chain reaction (PCR) or culture (virus culturing). However, virus culturing can only be done in high-security laboratories.

Diagnosing avian influenza virus infection can be challenging in critically ill patients. In patients who are less symptomatic, detecting the virus becomes even more difficult. avian influenza diagnosis can still be established by examining the body's immune response to the virus, but this takes time, as immunity typically develops in the third or fourth week.

Management

Management of avian influenza typically involves supportive therapy and antiviral medication. Supportive therapy aims to assist patients in recovery and manage symptoms or complications arising from the infection. For example, patients with fluid loss and electrolyte imbalances (electrically charged ions that help maintain fluid balance) require intravenous fluids and other medications to correct fluid and electrolyte balance. Patients with persistent fever may require antipyretic therapy. If a patient experiences respiratory distress leading to shortness of breath, they may receive supplemental oxygen and require close monitoring because they are at risk of respiratory failure.

Patients with respiratory failure require intubation and mechanical ventilation. avian influenza can cause organ failure, necessitating close monitoring to prevent deterioration. Treatment may need to be more aggressive to maintain the patient's stability.

Complications

Complications of avian influenza may include organ damage or failure, injuries during therapy, or coinfections with other viruses or bacteria. Respiratory function decline is common in patients requiring respiratory support. Additionally, chronic kidney failure may develop following acute kidney failure due to severe avian influenza. Furthermore, avian influenza infection can occur concurrently with other viruses or bacteria, exacerbating the patient's symptoms.

Prevention

The best prevention for avian influenza is to avoid sources of infection when possible. If someone works with birds, they should use appropriate personal protective equipment. When avian influenza is spreading in an area, comprehensive personal protective equipment is essential when working with birds. Additionally, regular handwashing with soap and water can reduce the spread of avian influenza viruses.

If you find birds that have died suddenly, you can contact your local authorities. They can help investigate the cause of bird deaths and prevent avian influenza outbreaks in the area.

Furthermore, when cooking poultry products (such as chicken, duck, and eggs), it is advisable to wash them thoroughly and cook them thoroughly. Raw poultry not only carries a high risk of avian influenza virus contamination but also bacteria such as Salmonella. Cooking food thoroughly can kill influenza viruses and harmful bacteria.

When to See a Doctor?

If you know of any birds that have died due to avian influenza, it is advisable to contact the nearest healthcare professional. You will be monitored for several days to watch for symptoms. You may also be given medications to prevent symptoms from appearing. If you experience symptoms such as red eyes, cough, fever, etc., it is advisable to see a doctor. avian influenza can be potentially fatal if not monitored and addressed promptly.