About Avian Flu

Overview

Avian influenza, also known as bird flu, is a contagious viral disease that primarily affects birds, including domestic poultry. It is caused by influenza A viruses, which are members of the Orthomyxoviridae family. Avian influenza viruses can be classified into two main forms based on the severity of disease they cause: low pathogenic avian influenza (LPAI) and highly pathogenic avian influenza (HPAI). LPAI generally causes mild symptoms in birds, while HPAI can result in high mortality rates in poultry species. Large outbreaks of HPAI are a concern because they may affect food supply.

Avian influenza mainly affects birds. There have been cases of infections in humans, although the risk is generally very low. The most common avian flu infection in humans is caused by the H5N1 influenza A virus. People get avian flu through contact with infected animals. It is very rare to become infected from another person. In humans, it may cause respiratory symptoms similar to flu symptoms. Symptoms may be mild to very severe. Treatment may include medicine to treat symptoms and antiviral medicine in some cases.

Causes and Risk Factors

Avian influenza is caused by viral infections with influenza type-A viruses that naturally exist in wild bird populations. These viruses can cross from wildlife to domestic animals and cause outbreaks in domestic poultry. Infected birds may shed the avian flu virus in their saliva, respiratory mucous, and feces. Human infection occurs when the virus is inhaled or gets into a person’s eyes, nose, or mouth.

People with higher risk of getting avian flu include people with:

  • Exposure to Infected Birds: Direct contact with infected birds or their secretions can increase the risk of contracting avian flu. This can occur through handling or working with infected poultry.
  • Occupational Exposure: People who work in close proximity to poultry, such as farmers or poultry workers, may have an increased risk of exposure to avian flu viruses.
  • Hygiene Practices: Poor hygiene practices, such as inadequate handwashing after handling birds or their products, can increase the risk of getting avian flu.

It's important to note that while these risk factors can influence an individual's likelihood of developing avian flu, they do not guarantee infection. Taking preventive measures such as practicing good hygiene and following appropriate safety protocols (such as wearing protective clothing, mask, and goggles when working with birds and removing shoes when entering the home after walking through areas where birds live) can help reduce the risk of contracting the disease.

Symptoms

The symptoms of avian flu can vary from person to person, but there are some common signs to look out for. These symptoms usually appear quickly, within 1 to 4 days after exposure to the virus. Some of the early symptoms of Avian Flu include:

  • Unusual tiredness
  • Stuffy or runny nose
  • Sneezing
  • Sore throat
  • Pink eye

These early symptoms may resemble those of a common cold. However, as the virus progresses or if the infection becomes more severe, additional symptoms may develop. These symptoms can include:

  • Chills
  • Excessive fatigue
  • Fever over 100.4°F
  • Headache
  • Muscle aches and pains
  • Shortness of breath
  • Persistent cough
  • Sweats
  • Weakness

In some cases, avian flu can also cause gastrointestinal issues such as nausea, diarrhea, or vomiting. It's important to note that not everyone who has avian flu will experience all of these symptoms. Some individuals may have relatively mild symptoms, while others may experience more severe ones.

Diagnosis

To diagnose avian flu, and exclude (rule out) other causes of symptoms, healthcare professionals use a combination of examinations, tests, and procedures, including:

Physical examination: As part of the physical examination, the doctor will check your nose, mouth and throat and listen to your lungs. They will ask questions about your symptoms, including when the symptoms began and exposures you may have had to people who are sick. It is important to tell the doctor if you have been exposed to birds or other animals that could be infected with the avian flu virus.

Blood tests: The doctor may send a blood sample to the lab to look for signs of infection or other causes of symptoms.

Throat or nose swab: The doctor may take a swab of your nose or throat to send to the lab to look for infection. Again, it will be important for the doctor to know if you may have been exposed birds or other animals that could be infected with the avian flu virus because the swab may need to be sent to a special lab.

Depending on symptoms and other findings from the examinations and test, additional tests or procedures, such as X-rays or other imaging studies may be performed.

Treatment Options

The goals of treatment for avian flu are to reduce symptoms, prevent complications, and improve overall health. Treatment options include:

Antiviral drugs: These drugs work by blocking the action of an enzyme that is essential for the virus to spread and replicate in the body. By inhibiting this enzyme, antiviral drugs can help reduce the severity and duration of symptoms. The duration of therapy for avian influenza is longer than for seasonal influenza, typically lasting 10 days compared to 5 days for seasonal flu.

Symptom relievers, such as

Fever and pain relievers for fever, headache, and body aches

Nasal decongestants

Cough medicines to help clear mucus or reduce the amount of coughing

Severe cases may require hospitalization to treat complications such as pneumonia, trouble breathing, and other infections that may develop.

It's important to initiate antiviral treatment as soon as clinical suspicion arises, even without diagnostic confirmation, due to the potential severity of avian influenza infections. Medication dosing may depend on individual factors, such as other conditions or medications, so it is important to consult the doctor before starting new medications. Side effects of medications can occur and should be reported to the doctor.

Progression or Complications

Avian flu may range from mild to very severe. Avian influenza virus infections are known to cause acute respiratory distress syndrome (severe breathing problems) at a relatively high frequency and have higher complication and death rates compared to seasonal influenza virus infections. In addition to respiratory distress and failure, avian flu complications may include pneumonia, bacterial infections including sepsis, and brain swelling.

It's important to consult with a healthcare professional if you have any concerns about avian flu or any other medical condition. They can provide personalized advice based on your specific situation.

What are the early signs of Avian Flu that I should look out for?

What preventive measures can I take to reduce my risk of contracting Avian Flu?

How is Avian Flu diagnosed and what treatment options are available?

/en/sources/healthline-can-you-have-the-flu-without-a-fever
Can you have the flu without a fever?
Healthline
2019-02-08
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7709030
Prevalence and Distribution of Avian Influenza Viruses in Domestic Ducks at the Waterfowl-Chicken Interface in Wetlands.
Ducks are a natural reservoir of influenza A viruses (IAVs) and can act as a reassortment vessel. Wetlands, such as Hakaluki and Tanguar haor in Bangladesh, have unique ecosystems including domestic duck (Anas platyrhynchos domesticus) rearing, especially household and free-range ducks. A cross-sectional study was, therefore, conducted to explore avian influenza status and its distribution and risk factors in the wetland areas. During the three consecutive winters of 2015-2017, specifically in December of these years, we collected a total of 947 samples including blood, oropharyngeal and cloacal swabs from domestic ducks (free-range duck (n = 312 samples) and household ducks (n = 635 samples) in wetlands. We screened serum samples using a nucleoprotein competitive enzyme-linked immunosorbent assay (c-ELISA) to estimate seroprevalence of IAV antibodies and swab samples by real-time reverse transcriptase polymerase chain reaction (rRT-PCR) to detect IA viral M gene. Eleven (11) M gene positive samples were subjected to sequencing and phylogenetic analysis. Serological and viral prevalence rates of IAVs were 63.8% (95% CI: 60.6-66.8) and 10.7% (8.8-12.8), respectively. Serological and viral RNA prevalence rates were 51.8% (95% CI: 47.2-56.4) and 10.2% (7.6-13.3) in Hakaluki haor, 75.6% (71.5-79.4) and 11.1% (8.5-14.3) in Tanguar haor, 66.3% (62.5-69.9) and 11.2% (8.8-13.9) in household ducks and 58.7% (52.9-64.2) and 9.6% (6.5-13.4) in free-range ducks, respectively. The risk factors identified for higher odds of AI seropositive ducks were location (OR = 2.9, 95% CI: 2.2-3.8,p< 0.001; Tanguar haor vs. Hakaluki haor), duck-rearing system (OR = 1.4, 1.1-1.8, household vs. free-range), farmer's education status (OR = 1.5, 1.2-2.0,p< 0.05 illiterate vs. literate) and contact type (OR = 3.0, 2.1-4.3,p< 0.001; contact with chicken vs. no contact with chicken). The risk factors identified for higher odds of AI RNA positive ducks were farmer's education status (OR = 1.5, 1.0-2.3,p< 0.05 for illiterate vs literate), contact type (OR = 2.7, 1.7-4.2,p< 0.001; ducks having contact with chicken vs. ducks having contact with waterfowl). The phylogenetic analysis of 11 partial M gene sequences suggested that the M gene sequences detected in free-range duck were very similar to each other and were closely related to the M gene sequences of previously reported highly pathogenic avian influenza (HPAI) and low pathogenic avian influenza (LPAI) subtypes in waterfowl in Bangladesh and Southeast Asian countries. Results of the current study will help provide significant information for future surveillance programs and model IAV infection to predict the spread of the viruses among migratory waterfowl, free-range ducks and domestic poultry in Bangladesh.
PubMed Central
2020-11-16
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7009863
Avian influenza overview October 2016-August 2017.
The A(H5N8) highly pathogenic avian influenza (HPAI) epidemic occurred in 29 European countries in 2016/2017 and has been the largest ever recorded in the EU in terms of number of poultry outbreaks, geographical extent and number of dead wild birds. Multiple primary incursions temporally related with all major poultry sectors affected but secondary spread was most commonly associated with domestic waterfowl species. A massive effort of all the affected EU Member States (MSs) allowed a descriptive epidemiological overview of the cases in poultry, captive birds and wild birds, providing also information on measures applied at the individual MS level. Data on poultry population structure are required to facilitate data and risk factor analysis, hence to strengthen science-based advice to risk managers. It is suggested to promote common understanding and application of definitions related to control activities and their reporting across MSs. Despite a large number of human exposures to infected poultry occurred during the ongoing outbreaks, no transmission to humans has been identified. Monitoring the avian influenza (AI) situation in other continents indicated a potential risk of long-distance spread of HPAI virus (HPAIV) A(H5N6) from Asia to wintering grounds towards Western Europe, similarly to what happened with HPAIV A(H5N8) and HPAIV A(H5N1) in previous years. Furthermore, the HPAI situation in Africa with A(H5N8) and A(H5N1) is rapidly evolving. Strengthening collaborations at National, EU and Global levels would allow close monitoring of the AI situation, ultimately helping to increase preparedness. No human case was reported in the EU due to AIVs subtypes A(H5N1), A(H5N6), A(H7N9) and A(H9N2). Direct transmission of these viruses to humans has only been reported in areas, mainly in Asia and Egypt, with a substantial involvement of wild bird and/or poultry populations. It is suggested to improve the collection and reporting of exposure events of people to AI.
PubMed Central
2017-10-16
/en/sources/healthline-flu-facts-incubation-period-and-when-its-contagious
Flu Facts: Incubation Period and When It’s Contagious
Healthline
2018-10-26
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10145843
Avian Influenza: Strategies to Manage an Outbreak.
Avian influenza (AI) is a contagious disease among the poultry population with high avian mortality, which generates significant economic losses and elevated costs for disease control and outbreak eradication. AI is caused by an RNA virus part of theOrthomyxoviridaefamily; however, onlyInfluenzavirus Ais capable of infecting birds. AI pathogenicity is based on the lethality, signs, and molecular characteristics of the virus. Low pathogenic avian influenza (LPAI) virus has a low mortality rate and ability to infect, whereas the highly pathogenic avian influenza (HPAI) virus can cross respiratory and intestinal barriers, diffuse to the blood, damage all tissues of the bird, and has a high mortality rate. Nowadays, avian influenza is a global public health concern due to its zoonotic potential. Wild waterfowl is the natural reservoir of AI viruses, and the oral-fecal path is the main transmission route between birds. Similarly, transmission to other species generally occurs after virus circulation in densely populated infected avian species, indicating that AI viruses can adapt to promote the spread. Moreover, HPAI is a notifiable animal disease; therefore, all countries must report infections to the health authorities. Regarding laboratory diagnoses, the presence of influenza virus type A can be identified by agar gel immunodiffusion (AGID), enzyme immunoassay (EIA), immunofluorescence assays, and enzyme-linked immunoadsorption assay (ELISAs). Furthermore, reverse transcription polymerase chain reaction is used for viral RNA detection and is considered the gold standard for the management of suspect and confirmed cases of AI. If there is suspicion of a case, epidemiological surveillance protocols must be initiated until a definitive diagnosis is obtained. Moreover, if there is a confirmed case, containment actions should be prompt and strict precautions must be taken when handling infected poultry cases or infected materials. The containment measures for confirmed cases include the sanitary slaughter of infected poultry using methods such as environment saturation with CO2, carbon dioxide foam, and cervical dislocation. For disposal, burial, and incineration, protocols should be followed. Lastly, disinfection of affected poultry farms must be carried out. The present review aims to provide an overview of the avian influenza virus, strategies for its management, the challenges an outbreak can generate, and recommendations for informed decision making.
PubMed Central
2023-04-17
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9783319
Protective Efficacy of Inactivated H9N2 Vaccine in Turkey Poults under Both Experimental and Field Conditions.
Low pathogenic avian influenza (LPAI) H9N2 virus is one of the major poultry pathogens associated with severe economic losses in the poultry industry (broiler, layers, breeders, and grandparents' flocks), especially in endemic regions including the Middle East, North Africa, and Asian countries. This work is an attempt to evaluate the efficacy of whole inactivated H9N2 vaccine (MEFLUVACTMH9) in turkey poults kept under laboratory and commercial farm conditions. Here, 10,000 white turkey poults (1-day old) free from maternally derived immunity against H9N2 virus were divided into four groups; G1 involved 10 vaccinated birds kept under biosafety level-3 (BLS-3) as a laboratory vaccinated and challenged group, while G2 had 9970 vaccinated turkeys raised on a commercial farm. Ten of those birds were moved to BLS-3 for daily cloacal and tracheal swabbing to check for the absence of any life-threating disease, before conducting analyses. G3 (10 birds) served as a non-vaccinated challenged control under BSL-3 conditions, while G4 (10 birds) was used as a non-vaccinated and non-challenged control under BSL-3 conditions. Sera were collected on days 7-, 14-, 21-, and 28-post-vaccinations to monitor the humoral immune response using a hemagglutination-inhibition (HI) test. At these same intervals, cloacal and tracheal swabs were also checked for any viral infection. The challenge was conducted 28 days post-vaccination (PV) using AI-H9N2 in BSL-3 by intranasal inoculation of 6-log10 embryo infective dose50(EID50). At 3-, 6-, and 10-days post-challenge, oropharyngeal swabs were taken from challenged birds to quantify viral shedding by quantitative polymerase chain reaction (qRT-PCR). The results of this study showed that vaccinated groups (G1/2) developed HI titers of 1.38, 4.38, 5.88, and 7.25 log2in G1 vs. 1.2, 3.8, 4.9 and 6.2 log2in G2 when measured at 7-, 14-, 21- and 28-days PV, respectively, while undetectable levels were recorded in non-vaccinated groups (G3/4). Birds in G3 showed 90% clinical sickness vs. 10% and 20% in G1/2, respectively, over a 10-day monitoring period following challenge. Vaccinated birds showed a significant reduction in virus shedding in terms of the number of shedders, amount of shed virus and shedding interval over the non-vaccinated challenged birds. Regarding mortality, all groups did not show any mortality, which confirms that the circulating H9N2 virus still has low pathogenicity and cannot cause mortality. However, the virus may cause up to 90% clinical sickness in non-vaccinated birds vs. 10% and 20% in laboratory- and farm-vaccinated birds, respectively, highlighting the role of the vaccine in limiting clinical sickness cases. In conclusion, under the current trial circumstances, MEFLUVACTM-H9 provided protective seroconversion titers, significant clinical sickness protection and significant reduction in virus shedding either in laboratory- or farm-vaccinated groups after a single vaccine dose.
PubMed Central
2022-12-19
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5732541
Evaluating the role of wild songbirds or rodents in spreading avian influenza virus across an agricultural landscape.
Avian influenza virus (AIV) infections occur naturally in wild bird populations and can cross the wildlife-domestic animal interface, often with devastating impacts on commercial poultry. Migratory waterfowl and shorebirds are natural AIV reservoirs and can carry the virus along migratory pathways, often without exhibiting clinical signs. However, these species rarely inhabit poultry farms, so transmission into domestic birds likely occurs through other means. In many cases, human activities are thought to spread the virus into domestic populations. Consequently, biosecurity measures have been implemented to limit human-facilitated outbreaks. The 2015 avian influenza outbreak in the United States, which occurred among poultry operations with strict biosecurity controls, suggests that alternative routes of virus infiltration may exist, including bridge hosts: wild animals that transfer virus from areas of high waterfowl and shorebird densities.
PubMed Central
2017-12-13
/en/sources/healthline-everything-you-need-to-know-about-the-flu
Everything You Need to Know About the Flu
Healthline
2020-08-31
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9072826
Assessing the Likelihood of High Pathogenicity Avian Influenza Incursion Into the Gamebird Sector in Great BritainviaDesignated Hatcheries.
The outbreaks of High Pathogenicity Avian Influenza (HPAI) in the United Kingdom in 2017 and 2021 had a substantial impact on the gamebird industry and highlighted to policymakers the importance of existing knowledge gaps for effective disease control. Despite the size of the industry, the impact of HPAI on the gamebird industry is not well-understood. To improve future disease preparedness, a veterinary risk assessment to explore the risk of HPAI incursion into the gamebird sector in Great Britainviaa designated hatchery was commissioned by Scottish Government Animal Health and Welfare Division. Hatchery designation is a legal requirement for hatcheries located within disease control zones or that have business links to premises located in disease control zones to continue operating during an HPAI outbreak. Several risk pathways were identified, which involved various management procedures associated with egg production through to the delivery of day-old chicks. The overall likelihood of the HPAI virus introduction into a designated hatchery through hatching egg movement is considered to be low (high uncertainty). The overall likelihood of onward transmission of the HPAI virus into gamebird rearing sites from a designated hatchery through day-old chick movement is also considered to be low (medium uncertainty). These risk levels are based on the assumption that relevant control measures are observed, as enhanced biosecurity is one of the requirements for hatchery designation. However, high uncertainties and variabilities were identified in the level of compliance with these biosecurity measures. Factors increasing the likelihood level include management practices typical to this sector, such as having multiple egg production sites, raising birds at outdoor sites, catching birds from the wild for egg production, having various scale of satellite farms in various locations, importing eggs and day-old chicks from overseas, as well as the proximity of the game farm to the infected premise or to higher risk areas. This study offers evidence for policymakers to help develop criteria for hatchery designation and proposes important mitigation strategies for future disease outbreaks specific for the gamebird sector.
PubMed Central
2022-04-22
/en/sources/healthline-early-flu-symptoms-in-adults-and-children
Early flu symptoms in adults and children
Healthline
2020-03-20
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10058720
Immune Control of Avian Influenza Virus Infection and Its Vaccine Development.
The avian influenza A virus (AIV) is naturally prevalent in aquatic birds, infecting different avian species and transmitting from birds to humans. Both AIVs, the H5N1 and H7N9 viruses, have the potential to infect humans, causing an acute influenza disease syndrome in humans, and are a possible pandemic threat. AIV H5N1 is highly pathogenic, whereas AIV H7N9 has comparatively low pathogenicity. A clear insight into the disease pathogenesis is significant to understand the host's immunological response, which in turn facilitates the design of the control and prevention strategies. In this review, we aim to provide comprehensive details on the pathogenesis and clinical features of the disease. Moreover, the innate and adaptive immunological responses to AIV and the recent studies conducted on the CD8+T cell immunity against AIVs are detailed upon. Further, the current status and advancement in the development of AIV vaccines, along with the challenges, are also discussed. The information provided will be helpful in combating the transmission of AIV from birds to humans and, thus, preventing severe outbreaks leading to pandemics worldwide.
PubMed Central
2023-03-04
/en/sources/healthline-how-long-is-the-incubation-period-for-the-flu
How long is the incubation period for the flu?
Healthline
2020-06-23