Disease Outbreak News Avian Influenza A(H9N2) - Ghana

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20 September 2024

Situation at a glance

On 26 August 2024, the International Health Regulations (IHR) National Focal Point (NFP) for Ghana notified the World Health Organization (WHO) regarding the country’s first reported human case of infection with a zoonotic (animal) influenza virus. Subsequent laboratory tests confirmed the presence of the avian influenza A(H9N2) virus. According to epidemiological investigations, the patient, under five years old, had no known history of exposure to poultry or any sick person with similar symptoms prior to the onset of symptoms. The Ghanaian government has implemented a series of measures aimed at monitoring, preventing, and controlling the situation. According to the IHR (2005), a human infection caused by a novel influenza A virus subtype is an event that has the potential for high public health impact and must be notified to the WHO. Based on currently available information, WHO assesses the current risk to the general population posed by A(H9N2) viruses as low, but is continuing to monitor these viruses and the situation globally.

Description of the situation

On 26 August 2024, the Ghana IHR NFP notified WHO of one confirmed human infection with an avian influenza A(H9N2) virus. This marks the first human infection with a zoonotic influenza virus reported from Ghana to WHO.

The patient is a child under five years old, residing in the Upper East region, which is located on the border with Burkina Faso.

The onset of the illness occurred on 5 May 2024, characterized by a sore throat, fever, and cough. On 7 May, the patient was seen at a local hospital, received a diagnosis of influenza-like illness, and was treated with antipyretics, antihistamines and antibiotics.

Respiratory samples collected on 7 May, tested positive for seasonal influenza A(H3N2) virus by polymerase chain reaction (PCR) on 15 May at the Ghana National Influenza Centre (NIC), Noguchi Memorial Institute for Medical Research.

On 9 July, genomic sequence analysis conducted by the Ghana NIC indicated an avian influenza A(H9) virus. Subsequently, an aliquot of the sample was dispatched to WHO Collaborating Centres (CC) located in the United Kingdom of Great Britain and Northern Ireland (The Francis Crick Institute) and the United States of America (the United States Centers for Disease Control and Prevention, US CDC), for additional testing and validation. On 6 August, the US CDC confirmed the samples as positive for influenza A(H9N2) virus.

Upon confirmation of the A(H9N2) virus infection, the Upper East Regional Health Directorate visited the patient and observed that they were experiencing a new onset of respiratory symptoms. Serum and respiratory specimens were obtained on that day and sent to the NIC for further analysis. The test results were negative for influenza and the patient has since fully recovered.

The patient had no known history of exposure to poultry or any sick person with similar symptoms prior to onset of symptoms. Respiratory samples from close contacts tested negative for influenza. No additional cases of human infection with influenza A(H9N2) viruses associated with this case have been identified in the community.

Illness among poultry has been reported in the Upper East Region, but the cause of the poultry disease had not been confirmed at the time of reporting. However, influenza A(H9N2) low pathogenicity avian influenza viruses have been reported in Ghanaian poultry farms since November 2017.

Epidemiology

Animal influenza viruses normally circulate in animals but can also infect humans. Infections in humans have primarily been acquired through direct contact with infected animals or contaminated environments. Depending on the original host, influenza A viruses can be classified as avian influenza, swine influenza, or other types of animal influenza viruses.

Avian influenza virus infections in humans may cause mild to severe upper respiratory tract infections and influenza-associated deaths have been reported in persons with or without comorbidities. Conjunctivitis, gastrointestinal symptoms, encephalitis and encephalopathy have also been reported.

Laboratory tests are required to diagnose human infection with influenza. WHO periodically updates technical guidance protocols for the detection of zoonotic influenza using molecular methods, for example PCR.

Public health response

The Ghanaian government has implemented a series of measures aimed at monitoring, preventing, and controlling the situation.

Enhanced case surveillance has been established, alongside the implementation of epidemiological investigations and the monitoring of close contacts.

Ongoing public risk communication initiatives are in place to raise public awareness and encourage the adoption of self-protection strategies, particularly among key occupational groups that are at a higher risk of exposure.

WHO risk assessment

This is the first human case of infection with a zoonotic influenza virus notified by Ghana. Laboratory testing confirmed the virus as an influenza A(H9N2) virus.

The majority of human infections with A(H9N2) viruses occur due to contact with infected poultry or environments that have been contaminated and typically result in mild clinical symptoms. Further human cases in persons with exposure to the virus in infected animals or through contaminated environments can be expected since the virus continues to be detected in poultry populations. To date, there has been no reported sustained human-to-human transmission humans of A(H9N2) viruses.

The existing epidemiological and virological evidence suggests that this virus has not acquired the capacity for sustained transmission among humans. Thus, the likelihood of sustained human-to-human spread is low. Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. However, if this occurs, further community-level spread is considered unlikely.

WHO advice

This case does not change the current WHO recommendations on public health measures and influenza surveillance.

Due to the constantly evolving nature of influenza viruses, WHO continues to stress the importance of thorough and timely epidemiologic investigation and global surveillance to detect and monitor virological, epidemiological and clinical changes associated with emerging or circulating influenza viruses that may affect human and animal health and timely virus-sharing for risk assessment.

In the case of a confirmed or suspected human infection caused by a novel influenza A virus with pandemic potential, including avian influenza virus, a thorough epidemiologic investigation (even while awaiting the confirmatory laboratory results) of a history of exposure to animals and/or travel should be undertaken along with contact tracing. The epidemiologic investigation should include early identification of unusual events that could signal person-to-person transmission of the novel virus. Clinical samples collected from suspected human cases should be tested and sent to a WHO Collaboration Centre for further characterization.

When there has been human exposure to a known outbreak of an influenza A virus in domestic poultry, wild birds or other animals or when there has been an identified human case of infection with such a virus, enhanced surveillance in potentially exposed human populations becomes necessary. Enhanced surveillance should consider the healthcare-seeking behaviour of the population. It could include a range of active and passive healthcare and/or community-based approaches, including enhanced surveillance in local influenza-like illness (ILI)/severe acute respiratory infection (SARI) systems, active screening in hospitals and of groups that may be at higher occupational risk of exposure, and inclusion of other sources such as traditional healers, private practitioners and private diagnostic laboratories.

The public should avoid contact with high-risk environments, such as live animal markets/farms and live poultry or surfaces that might be contaminated by poultry droppings.

Additionally, maintaining good hand hygiene through frequent hand washing with soap or using alcohol-based hand sanitizer is recommended.

The general public and at-risk individuals should immediately report instances of illness or unexpected deaths in animals to veterinary authorities. Handling sick or unexpectedly dead poultry including slaughtering, butchering, and preparing such poultry for consumption, should be avoided.

Any person exposed to potentially infected animals or contaminated environments who feels unwell should seek healthcare promptly and inform their healthcare provider of their possible exposure.

WHO does not recommend special traveler screening at points of entry or other restrictions due to the current situation of influenza viruses at the human-animal interface.

States Parties to the International Health Regulations (2005) are required to immediately notify WHO of any laboratory-confirmed case of a human infection caused by a new subtype of influenza virus. Evidence of illness is not required for this notification.

Further information

Citable reference: World Health Organization (20 September 2024). Disease Outbreak News; Avian Influenza A (H9N2) – Ghana. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON534