Avian influenza, commonly known as bird flu, is making headlines globally once again. Recent outbreaks have been reported, with H7N3 confirmed in the United States, H5N8 detected in Poland, Hungary, Bulgaria, the Czech Republic, Ukraine, and Germany, and H5N6 and H5N1 found in Vietnam and the Philippines. These countries have been forced to cull thousands of birds this year to curb the spread of the avian flu virus. This article from Thanhga will delve into the signs and symptoms of avian influenza, preventative measures, and treatment methods.
Signs and Symptoms of Avian Influenza in Poultry
Avian influenza is caused by the influenza A virus, which can infect both wild and domestic poultry. There are two primary types of avian influenza viruses based on their potential to cause disease: high pathogenic (HP) and low pathogenic (LP). HP strains can spread rapidly among flocks, causing severe, sudden multi-organ failure and high mortality rates. LP strains usually result in asymptomatic infections, respiratory issues, or decreased egg production.
Common symptoms indicating the presence of avian influenza in poultry include:
- Sudden death without prior signs
- Cyanosis of the comb (the fleshy part on the rooster’s head), wattles, and legs
- Swelling of the head, eyelids, comb, wattles, and hocks
- Soft or deformed eggs
- Decreased egg production
- Lethargy, reduced feed intake, and decreased mobility
- Diarrhea
- Nasal discharge
- Coughing or sneezing
- Feather ruffling
- Preventing Avian Influenza in Poultry
Historical Outbreaks of Avian Influenza H5N1
H5N1 has previously caused significant pandemics. The reasons for its dangerous nature include:
- Rapid Mutation: The virus can quickly evolve and generate new strains by acquiring genes from various animal species.
- Environmental Stability: The virus can survive in bird feces for up to 10 days, and its robust nature, combined with migratory bird behaviors, makes it highly transmissible.
- High Risk to Humans: H5N1 can lead to severe health complications. It is categorized into two types: high pathogenic avian influenza (HPAI) and low pathogenic avian influenza (LPAI).
- Human Transmission: The virus can spread from birds to humans and potentially between humans, posing a risk of pandemic.
- Environmental Persistence: The virus can endure in the environment for extended periods. It generally dies at 60°C in 30 minutes or 56°C in 3 hours. However, high pathogenic strains can survive longer (up to 35 days at 40°C) and can remain viable for years if frozen.
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Symptoms of Avian Influenza H5N1
Early Symptoms:
In the initial stage, symptoms typically include sudden high fever, fatigue, body aches, lethargy, and loss of appetite.
Advanced Symptoms:
As the disease progresses, symptoms become more severe and include:
- Persistent coughing, both dry and productive.
- High fever continuing for a prolonged period.
- Central nervous system involvement: altered consciousness, decreased alertness, memory impairment, throat pain, skin redness and warmth, coma, etc.
- Severe headaches, temple pain, eye socket pain, joint pain, and overall body aches.
Prompt medical evaluation and treatment are essential to manage these symptoms and prevent serious complications.
Potential Complications:
Without timely treatment, avian influenza H5N1 can lead to severe complications, including:
- Secondary Infections: High risk of ear, nose, and throat infections, particularly in children.
- Respiratory Damage: Conditions such as pneumonia and bronchitis.
- Multi-Organ Failure: Including liver, kidney, and brain failure, and severe immune system suppression due to a drastic drop in white blood cells.
- Other Complications: Myocarditis, pericarditis, lymphocytic meningitis, brain edema, disseminated intravascular coagulation, etc.
Treatment and Care for Avian Influenza H5N1
Medication:
Currently, the antiviral medication Oseltamivir (Tamiflu) is commonly prescribed for treating H5N1, provided it is administered within 48 hours of symptom onset. If Tamiflu is ineffective, Zanamivir (Relenza) may be used as an alternative to manage symptoms and prevent complications.
For high fever above 38°C and severe coughing, Paracetamol may be used. For persistent dry cough, Codeine is recommended. In severe cases with risk of septic shock, corticosteroids may be necessary.
Note: Salicylate drugs (such as aspirin) should be avoided as they can lead to Reye’s syndrome, a serious condition especially dangerous for children.
Home Care:
Mild cases of H5N1 can be managed at home, but severe cases require hospitalization for intensive care and monitoring to prevent serious complications.
For home care:
- Rest: Ensure adequate rest and avoid stress or vigorous activities.
- Environment: Keep the living area clean, well-ventilated, and at a moderate temperature.
- Diet: Consume soft, easily digestible foods and stay hydrated. Avoid cold foods which can irritate the throat and delay recovery.
- Nasal Care: Use nasal sprays to keep the nasal passages clean and prevent infection.
- Throat Care: Rinse the throat with diluted saline solution 2-3 times daily to alleviate throat inflammation and pain.
Vaccination and Prevention
Currently, no vaccine specifically prevents H5N1, but vaccination against other strains of influenza A can help reduce the spread and differentiate H5N1 from other viruses. Regular monitoring and adherence to public health guidelines are crucial for managing and preventing avian influenza outbreaks.
Treatment Options for Avian Influenza
Oseltamivir and Zanamivir (Neuraminidase Inhibitors):
Oseltamivir and zanamivir are commonly prescribed neuraminidase inhibitors used in the treatment of avian influenza. These medications are administered at standard dosages to help manage the infection.
Baloxavir (Endonuclease Inhibitor):
Baloxavir, an endonuclease inhibitor, is another antiviral option. This drug, which targets the polymerase acidic protein, is indicated for the treatment of uncomplicated acute influenza in patients aged 12 years and older who have been symptomatic for 48 hours or less.
Resistance Concerns:
It is important to note that strains of influenza such as H7N9 and H5N1 have shown resistance to previous antiviral drugs like amantadine and rimantadine. There have also been reports of reduced sensitivity or resistance to oseltamivir in some cases.
Vaccination can be an effective tool to support eradication programs when combined with other control measures. Emergency vaccination to slow the spread of the disease can serve as an alternative to early culling, helping to protect other healthy flocks from infection.