Bird Flu in Mexico: The World Health Organization (WHO) on Wednesday reported the first human death caused by bird flu in Mexico. The victim, a resident of Mexico, died after suffering from symptoms of avian influenza A (H5N2).
According to WHO, the Mexico International Health Regulations (IHR) National Focal Point (NFP) reported to PAHO/WHO a confirmed fatal case of human infection with avian influenza A(H5N2) on 23 May 2024.
“This is the first laboratory-confirmed human case of infection with an influenza A(H5N2) virus reported globally and the first avian H5 virus infection in a person reported in Mexico,” WHO said in a statement.
Although the source of exposure to the virus in this case is currently unknown, A(H5N2) viruses have been reported in poultry in Mexico, the global health agency stated.
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 available information, WHO assesses the current risk to the general population posed by this virus as low.
‘No history of exposure to poultry or other animals’
In its statement, WHO said that the 59-year-old patient had no history of exposure to poultry or other animals. However, he had multiple underlying medical conditions.
The patient’s relatives reported that the case had already been bedridden for three weeks, for other reasons, prior to the onset of acute symptoms.
“On 17 April, the case developed fever, shortness of breath, diarrhoea, nausea and general malaise. On 24 April, the case sought medical attention, was hospitalized at the National Institute of Respiratory Diseases “Ismael Cosio Villegas” (INER per its acronym in Spanish) and died the same day due to complications of his condition,” WHO reported.
According to the UN health body’s statement, results from Real-Time Polymerase Chain Reaction (RT-PCR) of a respiratory sample collected and tested at INER on 24 April indicated a non-subtypeable influenza A virus.
On 8 May, the sample was sent for sequencing to the Laboratory of Molecular Biology of Emerging Diseases Center for Research in Infectious Diseases of INER, which indicated that the sample was positive for influenza A(H5N2).
On 20 May, the sample was received at the Institute of Epidemiological Diagnosis and Reference of the Mexico National Influenza Centre, for analysis by RT-PCR, obtaining a positive result for influenza A. On 22 May, sequencing of the sample confirmed the influenza subtype was A(H5N2).
Meanwhile, no further cases were reported during the epidemiological investigation.
Of the 17 contacts identified and monitored at the hospital where the case died, one reported a runny nose between 28 and 29 April. Samples taken from these hospital contacts between 27 and 29 May tested negative for influenza and SARS-CoV 2.
“12 additional contacts (seven symptomatic and five asymptomatic) were identified near the case’s residence. Samples of pharyngeal exudate, nasopharyngeal swabs and serum were obtained from these individuals. On 28 May, the InDRE reported that all twelve samples from contacts near the patient’s residence tested negative for SARS-CoV-2, influenza A and influenza B, as determined by RT-PCR. The results of the serological samples are pending,” WHO stated.
In March this year, a high pathogenicity avian influenza A(H5N2) outbreak was detected in a backyard poultry farm in the state of Michoacán, which borders the State of Mexico where the patient was residing.
What are the causes of H5N2 bird flu infection?
Usually, animal influenza viruses circulate in animals but can also infect humans. A human can contract the infection when he or she comes in 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, WHO stated.
What are symptoms of H5N2 bird flu infection?
Avian influenza virus infections in humans may cause mild to severe upper respiratory tract infections and can be fatal. According to WHO, Conjunctivitis, gastrointestinal symptoms, encephalitis and encephalopathy have also been reported.
The main symptoms of bird flu can appear very quickly and include:
- a very high temperature or feeling hot or shivery
- aching muscles
- headache
- a cough or shortness of breath
Other early symptoms may include:
- diarrhoea
- sickness
- stomach pain
- chest pain
- bleeding from the nose and gums
- conjunctivitis
- It usually takes 3 to 5 days for the first symptoms to appear after you’ve been infected.
How H5N2 Bird Flu infection is treated?
Some antiviral drugs, notably neuraminidase inhibitors (oseltamivir, zanamivir), can reduce the duration of viral replication and improve survival prospects for some cases.
“There are no specific vaccines for preventing influenza A(H5) virus infection in humans. Candidate vaccines to prevent A(H5) infection in humans have been developed for pandemic preparedness purposes,” the global health agency stated.
