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From the Centers for Disease Control and Prevention
October 17, 2012

Notes from the Field: Highly Pathogenic Avian Influenza A (H7N3) Virus Infection in Two Poultry Workers — Jalisco, Mexico, July 2012

JAMA. 2012;308(15):1519-1520. doi:

MMWR. 2012;36:726-727.

During June–August 2012, Mexico's National Service for Health, Safety, and Food Quality reported outbreaks of highly pathogenic avian influenza (HPAI) A (H7N3) virus in poultry on farms throughout the state of Jalisco.1,2 This report describes two cases of conjunctivitis without fever or respiratory symptoms caused by HPAI A (H7N3) virus infection in humans associated with exposure to infected poultry.

Patient 1. On July 7, a poultry worker aged 32 years complaining of pruritus in her left eye was examined at a clinic in Jalisco. Physical findings included redness, swelling, and tearing. Conjunctivitis was diagnosed; the patient was treated symptomatically and recovered fully. Because the patient had collected eggs in a farm where HPAI A (H7N3) virus was detected, the Institute for Epidemiological Diagnosis and Reference, Mexico, tested ocular swabs from both of her eyes for influenza A (H7) by real-time reverse transcription–polymerase chain reaction (rRT-PCR), and embryonated chicken eggs were inoculated for viral isolation. The swab material was positive for influenza A (H7) virus by rRT-PCR and virus was isolated from each eye. These findings were reported to the World Health Organization on July 19, and full genome sequences (CY125725–32) were uploaded to GenBank. The virus was closely related by nucleotide sequence to previously reported HPAI A (H7N3) viruses collected during poultry outbreaks in Jalisco with sequences available in GenBank (JX397993, JX317626).

Patient 2. A man aged 52 years, who was a relative of patient 1 and worked on the same farm, developed symptoms consistent with conjunctivitis on July 10 and sought care at a local clinic on July 13. He was treated symptomatically and recovered without sequelae. When public health authorities became aware of this patient, they obtained eye swabs, which were tested by rRT-PCR, revealing influenza A (H7).

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.

Avian influenza A viruses are designated as HPAI or low pathogenicity avian influenza (LPAI) based on molecular characteristics of the virus and the ability of the virus to cause disease and mortality in birds.3 To date, only influenza A (H5) and (H7) subtypes have been described as HPAI. Influenza A (H7) subtype viruses have been detected in wild birds in many parts of the world and can cause outbreaks in poultry. Influenza A (H7) infection in humans is uncommon, but can occur after direct contact with infected birds, especially during outbreaks of influenza A (H7) virus among poultry.4 Illness can include conjunctivitis without fever, upper respiratory tract symptoms, or both,4,5 and severity can range from mild to fatal.4 In the United States, avian influenza outbreaks in poultry are rare, but they are detected and reported sporadically. In the United States, only two cases of illness with LPAI A (H7) virus infection are known to have occurred in humans, both of whom recovered.6,7

The conjunctivitis cases in Jalisco most likely represent HPAI A (H7N3) virus transmission from infected poultry to humans through direct contact. United States agricultural, public health, and clinical personnel should be aware of these poultry outbreaks with transmission to humans in a neighboring country. Persons working with poultry known or suspected to be infected with influenza A viruses should use appropriate personal protective equipment, including face masks, gloves and eye protection (e.g., goggles). Clinicians and epidemiologists should consider avian influenza A virus infection in patients who have conjunctivitis or ILI and have contact with poultry in areas with known avian influenza outbreaks. Clinicians who suspect avian influenza A virus infections in humans should obtain a conjunctival or respiratory specimen, or both, depending on signs and symptoms, and submit samples to a national, regional, or state public health laboratory to enable specific influenza testing. Clinicians also should consider early empiric antiviral treatment of suspected cases with a neuraminidase inhibitor.8,9 Public health officials should survey family members and contacts of infected persons to find cases of human-to-human transmission.

Reported by:

Gisela Barrera-Badillo, MSc, Ernesto Ramirez-Gonzalez, PhD, Rodrigo Aparicio-Antonio, Tatiana Nuñez-Garcia, Dayanira Arellano-Suarez, Patricia Alcantara-Perez, MSc, Abril Rodriguez-Maldonado, Brisia Rodriguez-Reyes, Claudia Wong-Arambula, Elizabeth Gonzalez-Duran, MSc, Joanna Ortiz-Alcantara, MSc, Alberto Diaz-Quiñonez, PhD, Irma Lopez-Martinez, MSc, Instituto de Diagnóstico y Referencia Epidemiológicos; Gustavo Reyes-Teran, MPH, Joel Vazquez-Perez, PhD, Santiago Avila-Rios, PhD, Instituto Nacional de Enfermedades Respiratorias; Guadalupe Castañeda-Lopez, MD, Armando Robles-Cruz, MD, Hector Montoya-Fuentes, PhD, Victor Borja-Aburto, PhD, Instituto Mexicano del Seguro Social; Cuitlahuac Ruiz-Matus, MD, Jesus Felipe Gonzalez-Roldan, MD, Dirección General de Epidemiología; Pablo Kuri-Morales, MD, Subsecretaría de Prevención y Promoción de la Salud, Mexico. Todd Davis, PhD, Julie Villanueva, PhD, Vic Veguilla, MPH, Marc-Alain Widdowson, DVM, Joseph Bresee, MD, Eduardo Azziz-Baumgartner, MD, Jerome Tokars, MD, Timothy Uyeki, MD, Alexander Klimov, PhD, Stephen Lindstrom, PhD, Bo Shu, MD, Nancy Cox, PhD, Influenza Div, National Center for Immunization and Respiratory Diseases, CDC. Corresponding contributor: Alberto Díaz-Quiñonez, alberto.diaz@salud.gob.mx, 555-341-1101 (Mexico).

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