Highly pathogenic avian influenza detected in Mexico

Two workers contract conjunctivitis following contact with poultry infected with highly pathogenic avian influenza A (H7N3).

Outbreaks of highly pathogenic avian influenza (HPAI) A (H7N3) were reported in Jalisco, Mexico, during June to August 2012. The virus, which was reported by Mexico's National Service for Health, Safety, and Food Quality, was found in poultry on farms throughout Jalisco. In the September 14 Morbidity and Mortality Weekly Report (MMWR), CDC reports two human cases of H7N3 infection that were associated with exposure to infected poultry and resulted in conjunctivitis without fever or respiratory symptoms.

A 32-year-old woman and 52-year-old man were diagnosed with conjunctivitis that resolved fully following treatment. The patients were relatives and worked at the same poultry farm. As H7N3 virus had been detected at the farm, Mexico's Institute for Epidemiological Diagnosis and Reference tested ocular swabs from the patients' eyes for influenza A (H7) by real-time reverse transcription–polymerase chain reaction. The swab material tested positive for influenza A (H7) virus, which was isolated from patients' eyes. Genomic data later revealed that the virus was closely related by nucleotide sequence to previous H7N3 viruses collected during poultry outbreaks in Jalisco.

CDC stated the following in its MMWR report: "Mexico has continued its efforts to contain poultry outbreaks in affected areas in Jalisco. Those efforts include quarantining affected farms, culling infected birds, vaccinating uninfected birds, and disinfecting contaminated areas. Government agencies also have provided personal protective equipment to farm personnel and are conducting active surveillance for influenza-like illness (ILI) and severe acute respiratory illness at two sentinel sites near the outbreak."

The agency further described that only influenza A (H5) and (H7) subtypes have been categorized as HPAI. Influenza A (H7) subtype viruses have been detected in wild birds in many areas around the globe and can cause outbreaks in poultry. In addition to conjunctivitis without fever, illness can also include upper respiratory tract symptoms, with severity ranging from mild to fatal.

CDC also noted that, although rare in the United States, avian influenza outbreaks in poultry do occur sporadically. Two human cases of illness with low-pathogenicity avian influenza A (H7) virus infection are known to have occurred in the United States, and both individuals recovered.

The agency recommends that appropriate personal protective equipment (e.g., face masks, gloves, eye protection such as goggles) be worn by individuals working with poultry that is known or suspected to be infected with influenza A viruses. Health professionals who believe that a patient has been infected with avian influenza A virus should obtain a conjunctival or respiratory specimen, or both specimens, depending on the signs and symptoms exhibited. Samples then should be submitted to a national, regional, or state public health laboratory to enable specific influenza testing. Early empiric antiviral treatment with a neuraminidase inhibitor can be considered in suspected cases of avian influenza A virus.

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