Human infection with avian influenza A(H5N1) ｰ India

On 21 July 2021, the National IHR focal point of India notified WHO of one human case of avian Influenza A(H5N1) from Haryana state, northern India. This is the first reported case of human infection of influenza A(H5N1) virus in India.

The patient was a boy under 18 years of age with a recently diagnosed underlying illness in June 2021. Shortly after immunosuppressive treatment was initiated at the hospital, he presented with fever, cough, upper respiratory symptoms and breathing difficulty on 12 June. His condition progressed to acute respiratory distress syndrome and he was mechanically ventilated but died on 12 July. In the past year, the boy resided with a family member who owned a butchery in Haryana state. Based on initial investigations, there were no reports of poultry sickness or deaths from a nearby poultry farm in the village where he resided. The source of infection is unknown at this time and none of his family members have shown similar symptoms thus far.

On 7 and 11 July 2021, respiratory samples from the patient tested positive by reverse transcriptase -polymerase chain reaction (RT-PCR) at the All India Institute of Medical Science hospital for influenza A and influenza B viruses but negative for SARS-CoV-2 and other respiratory viruses. On 13 July, the samples were sent to National Institute of Virology, a WHO reference laboratory for influenza, for subtyping. Samples were tested for seasonal viruses of influenza A and influenza B, as well as avian influenza subtypes H5, H7, H9 and H10 by RT-PCR. On 15 July, the samples tested positive for influenza A(H5N1) and influenza B/Victoria lineage viruses. Whole genome sequencing and virus isolation is ongoing.

Local and national health authorities have taken the following monitoring, prevention and control measures:

• Conducting further epidemiological investigation on the origin of infection of the case, including a multidisciplinary rapid response team (comprising public health and animal health officials) supporting the state of Haryana;
• Strengthened surveillance, including enhanced monitoring of febrile cases (house to house surveys for fever surveillance conducted by health care workers) within a 10 km radius of the patient’s residence;
• Disinfected the patient’s residence and the surrounding environment;
• Directed all health institutions in the district to report any suspected cases of human infection with avian influenza;
• Closely traced and managed contacts of the case, including health care workers at the medical facility where the case was provided care;
• Performed risk communication activities to heighten public awareness, including for personal protective measures;
• Conducted animal surveillance by the animal husbandry department.

Available information and initial field investigations suggest that no additional cases have been suspected, indicating a low likelihood of human-to-human transmission. Further sporadic cases of human infection with avian influenza A(H5) viruses may be reported because these viruses have been occasionally detected in poultry populations in India. The risk assessment will be reviewed as necessary, should further epidemiological or virological information become available.

India has reported outbreaks of avian influenza A(H5N1) in poultry farms every year since it was first reported in a poultry farm in Maharashtra State in February 2006. In January and February 2021, Haryana state reported an outbreak of avian influenza A(H5N8) in Panchkula district, which severely affected poultry in the area. In that outbreak, samples collected from birds from four poultry farms tested positive for avian influenza A(H5N8).

Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. If this were to occur, further community level spread is considered unlikely as this virus has not acquired the ability to transmit easily among humans.

The detection of this case does not change current WHO recommendations on public health measures and surveillance of influenza. The primary risk factor for human infection with avian influenza is direct or indirect exposure to infected poultry (live or dead) or wildlife, as well as contaminated environments such as live bird markets. Additional risk factors include slaughtering, defeathering, handling carcasses of infected poultry, and preparing poultry for consumption, especially in household settings.

As at all times, 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 or bird faeces. Hand hygiene with frequent handwashing with soap and water or use of alcohol-based hand sanitizer is recommended.

Good food safety practices such as keeping cooking environments clean, separating raw and cooked food, and cooking food thoroughly, should also be followed. There is no evidence to suggest that influenza A(H5), A(H7N9) or other avian influenza viruses can be transmitted to humans through properly cooked poultry. There is no epidemiological evidence to suggest that people have been infected with avian influenza by consumption of eggs or egg products. However, eggs from areas with outbreaks in poultry should not be consumed raw or partially cooked (with runny yolk).

Health care workers preforming aerosol-generating procedures should use airborne precautions. Standard contact and droplet precautions and appropriate personal protective equipment should be made available and used during epidemics.

Due to the constantly evolving nature of influenza viruses, WHO continues to stress the importance of global surveillance to detect virological, epidemiological and clinical changes associated with circulating influenza viruses that may affect human or animal health, as well as timely sharing of viruses to inform risk assessments.

In the case of a confirmed or suspected human infection caused by a novel influenza virus with pandemic potential, including avian influenza or variant viruses, a thorough epidemiologic investigation should be conducted (even while awaiting the confirmatory laboratory results) on the history of exposure to animals, of travel, and contact tracing. The epidemiologic investigation should include early identification of unusual respiratory events that could signal human-to-human transmission of the novel virus. Additionally, clinical samples collected from the time and place that the case occurred should be tested and sent to a WHO Collaboration Centre for further characterization.

All human infections caused by a novel influenza subtype are notifiable under the International Health Regulations [IHR (2005)] and State Parties to the IHR (2005) are required to immediately notify WHO of any laboratory-confirmed case of a recent human infection caused by an influenza A virus with the potential to cause a pandemic. Evidence of illness is not required for this report. WHO does not recommend any specific measures for travellers, and advises against the application of any travel or trade restrictions in relation to this event based on the currently available information.

• Cumulative number of confirmed human cases for avian influenza A(H5N1), 2003-2021, reported to WHO, as of 15 April 2021
• WHO Global Influenza Programme, Human-animal interface
• WHO Health topic, Influenza (avian and other zoonotic)
• WHO Factsheet, Influenza (avian and other zoonotic)
• WHO Monthly Risk Assessment Summary: Influenza at the human-animal interface
• Protocol to investigate non-seasonal influenza and other emerging acute respiratory diseases
• Maintaining surveillance of influenza and monitoring SARS-CoV-2 – adapting Global Influenza Surveillance and Response System (GISRS) and sentinel systems during the COVID-19 Pandemic
• Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005)
• Summary of Key Information Practical to Countries Experiencing Outbreaks of A(H5N1) and Other Subtypes of Avian Influenza