Commonly known as the flu, influenza is an infectious disease that spreads around the world in seasonal epidemics. As a major health threat, the flu causes substantial illness and death each year. Respiratory diseases, particularly pneumonia, are the number one killer of children in developing countries and most cases of pneumonia start with a viral infection like influenza. Information about seasonality and prevalence of influenza is crucial for development of effective prevention and control strategies, yet limited data exist on the epidemiology of influenza in tropical countries.
Launched in 2007, SSI’s Influenza Program is defining the burden and seasonality of influenza in Nicaragua, demonstrating that it is indeed a major problem in Nicaragua and that vaccination is needed. As part of the program – supported by the Nicaraguan Ministry of Health and the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC) – nasal and throat swabs are collected from study participants who have flu-like symptoms. While the study has already revealed patterns of seasonality, multiple years’ worth of data will be needed for accurate information. In addition to influenza testing, analysis for other respiratory diseases has been set up at the Ministry of Health. This capacity proved critical during a dramatic outbreak of what turned out to be Respiratory Syncytial Virus (RSV) in August 2008, which killed many infants and the pandemic flu that affected the globe in 2009.
Current Influenza Studies in Nicaragua
SSI currently manages 3 influenza studies that will help elucidate the burden of influenza and the mechanisms of influenza transmission in Managua, Nicaragua. This research includes two interrelated cohort studies: the Pediatric Influenza Cohort Study and the Influenza Birth Cohort. In addition, we are engaged in a Household Transmission study.
- The Pediatric Cohort study provides primary care to approximately 1,600 children ages 0-14 years at the study health center, the Health Center Socrates Flores Vivas of the Nicaraguan Ministry of Health. Children who present to the health center with symptoms of influenza are tested using molecular methods (real-time PCR) for influenza infection and followed though their illness. This setup is called “passive surveillance” as the participants have to attend the health center to be taken care off.
- The Influenza Birth Cohort study is an “active surveillance” study were participants are enrolled at birth and visited at least once a week by our team to collect symptom surveys and identify potential respiratory illnesses. A changeling setup from a logistical point of view but very rewarding as it bring us even closer to the community we work in. Both studies provide invaluable information about the epidemiology of influenza and other respiratory illnesses in Nicaragua, as well as insights into clinical presentation and immune responses of children infected with the influenza virus.
- The third study in our portfolio of community-based influenza studies is the Influenza Household Transmission study. In this study, we identify index cases of influenza and enroll household members over a period of 30 to 45 days. This study aims to characterize the factors that impact influenza transmission in households in a tropical setting such as Managua. In this study, cases are identified and household members are invited to participate. Households are visited every other day for an initial period of 10-12 days; and one more time after 4 weeks. Samples and clinical information are collected at each visit. Studying influenza at this level is key as up to 70% of transmission of influenza may occur in the household and it is a site where we can intervene to slow the spread of the disease.