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Office of Binational Border Health

Border Infectious Disease Surveillance - Influenza and Other Respiratory Infections


Viral and bacterial respiratory infections are a major cause of morbidity and mortality worldwide. In the US, influenza and other respiratory viral infections lead to more than 400,000 hospitalizations in individuals younger than 18 years of age every year. International organizations such as the World Health Organization and the Pan-American Health Organization recognize the importance that surveillance of influenza-like illness (ILI) and severe acute respiratory infection (SARI) play in protecting the public from epidemics and pandemics of influenza and other respiratory infections. After the 2009 influenza pandemic, US-Mexico surveillance systems were designed to monitor the burden of respiratory infections in the highly mobile communities that live, play, and work in the Southern border of the US.

Severe Acute Respiratory Infection (SARI) Surveillance


Since 2009, the Imperial County Public Health Department has conducted year-round enhanced surveillance of SARI at two acute-care hospitals: El Centro Regional Medical Center and Pioneers Memorial Hospital. Recently, a hospital in Mexicali, Baja California has been added as a sentinel site for SARI. Specimens collected at these sites are tested for viral and bacterial respiratory pathogens at the Naval Health Research Center (NHRC) laboratory in San Diego, CA.


For the 2016-17 influenza season, 332 samples were collected and tested from SARI patients. Information collected about the respiratory pathogens circulating in Imperial County through SARI surveillance helps public health officials understand the burden of disease in the area, and can be helpful in designing prevention and intervention methods.

Influenza-Like Illness (ILI) Surveillance


ILI cases are defined as those that present with fever ≥ 100°F, and either sore throat or cough; or any cause of pneumonia. BIDS enrolls ILI patients at the community clinic San Ysidro Health near the Tijuana border. Nasopharyngeal swabs are collected for influenza rapid tests and further tested for molecular identification of respiratory pathogens.


For the 2015-16 and 2016-17 influenza seasons, 361 ILI samples were processed by BIDS. The information collected from test results and case report forms filled out can help inform public health campaigns, alert of outbreaks, and report the tendencies of disease spread on the US-Mexico border region.

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