WHO | Avian Influenza A (H5N1)

The Ministry of Health of the Lao People’s Democratic Republic (PDR) has reported a case of human infection with the bird flu A (H5N1) virus. It is the case of a one-year-old female who on 13 October 2020 developed symptoms of fever, productive cough, shortness of breath and runny nose. She was hospitalized on October 16 due to illness and was discharged on October 19. As part of the control of severe acute respiratory infection (SARI), a sample was collected on the date of hospitalization and on October 28, a verified reverse transcription polymerase chain reaction (RT-PCR) was confirmed positive for avian influenza A (H5N1). National Center for Laboratory and Epidemiology (NCLE).

Among the patient’s close contacts, one contact developed fever and cough after the onset of the disease in that case. Samples collected from all household contacts, including symptomatic contact, were negative for influenza A viruses.

After further investigation, there was domestic poultry in the residence. There was no family travel history 14 days before the onset of symptoms in the family.

This is the third case of avian influenza A (H5N1) virus in humans recorded from Lao PDR since 2005; two cases, including two deaths, were recorded in 2007.

Public health response

The Lao PDR government has taken the following monitoring, prevention and control measures as described in detail in the Joint National Plan for Avian Influenza Preparedness and Contingencies A (H7N9) and A (H5N1) for the Lao PDR:

• Case management and case isolation and close contacts
• Examination of close contacts
• A meeting of the Provincial Department of Health and the Provincial Department of Agriculture and Forestry was held to discuss and plan a rapid response
• An epidemiological study is underway that includes veterinarians from the Provincial Department of Agriculture and Forestry
• Communication on risk for the public and health workers has been initiated
• Increased surveillance and disinfection of the surrounding environment, including the patient’s residence and areas of suspected exposure
• Laboratory samples will be shared with the WHO Cooperation Center

WHO risk assessment

To date, 862 cases of influenza A (H5N1) have been reported by the WHO since 2003, including three from the Lao PDR. Almost all cases of avian influenza A (H5N1) infection in humans are associated with close contact with infected live or dead birds or environments contaminated with influenza A (H5N1) viruses. Human infection can cause serious illness and reportedly has a high mortality rate. As the virus continues to be detected in poultry populations, further cases in humans can be expected.

Currently available epidemiological and virological evidence suggests that A (H5N1) viruses have not acquired the ability to be transmitted permanently among humans, so the likelihood of spreading from human to human is low. If infected people from the affected areas travel abroad, their infection can be detected in another country during the trip or after arrival. If this were to happen, further spread at the community level is considered unlikely because this virus has not acquired the ability to be easily transmitted among humans.

This case does not change the current WHO recommendations on public health measures and influenza surveillance. Thorough research into any human infection with the untyped influenza A virus is necessary.

WHO advice

Due to the ever-evolving nature of influenza viruses, the WHO continues to emphasize the importance of global surveillance to detect virological, epidemiological and clinical changes associated with circulating influenza viruses that may affect human (or animal) health while sharing such viruses and related information for further characterization and assessment. risk.

All human infections caused by a new subtype of influenza are reported under International Health Regulations (IHR) and IHR (2005) States Parties are required to notify the WHO immediately of any laboratory-confirmed case of a recent human infection caused by an influenza A virus that could potentially cause a pandemic. No evidence of disease is required for this report .

In case of confirmed or suspected human infection caused by a new influenza virus with pandemic potential, including a variant of the virus, a thorough epidemiological investigation (even pending confirmatory laboratory results) of animal exposure history, travel and contact search should be conducted. Epidemiological research should include early identification of unusual respiratory events that could signal transmission of the new virus from person to person, and clinical samples collected from the time and place of the case should be tested and sent to the WHO Collaboration Center for further characterization.

General hygiene measures should be followed, such as regular hand washing before and after touching animals and potentially contaminated environments, and avoiding contact with sick animals. The WHO does not recommend special measures for travelers.

The WHO does not advise special checks at entry points in connection with this event, nor does it recommend the application of any travel or trade restrictions.