Focus Area - Diarrheal Disease

According to the WHO, diarrheal diseases is the second leading cause of deaths in children.  Globally, there are nearly 1.7 billion cases of childhood diarrheal disease every year. In 2017, 1.6 million people died from diarrheal diseases; one-third were children under five years old. Despite being treatable and preventable, diarrhea related morbidity and mortality remains high, especially in low- and middle-income countries (LMICs). 

Cholera continues to inflict high rates of morbidity and mortality. Approximately 1.3 billion people living in 69 countries are at risk of contracting the disease. Cholera outbreaks have been increasing in frequency, intensity, and duration, indicating more effective approaches to prevention and control are required. Enterotoxigenic E. coli (ETEC) and Shigella spp (Shigella) are the leading causes of morbidity and mortality due to diarrhea. Repeated infections could lead to faltering growth and potentially impact cognitive development in the children of the developing world. Although vaccine candidates against Shigella and ETEC are being developed, we are still a decade away from licensure. 

Current diagnostic methods for cholera, ETEC and Shigella are often labor and resource intensive. These methods require competent laboratory support and technical skills, which are not always available at the health facilities or laboratories. All three can be diagnosed through culture on media, and isolated to determine toxin genes. However, culturing method is not sensitive and takes up to 3 days to diagnose, which makes it not ideal for outbreaks.  

Rapid, sensitive, and reliable diagnostic assays are needed to provide reliable surveillance data to guide long-term policies and interventions. The currently available Rapid Diagnostic Tests (RDTs) for cholera demonstrated wide variations in sensitivity and specificity and therefore are not reliable. The significant infrastructure requirements for diagnosis of ETEC and Shigella make determining the true disease burden difficult to quantify in LMICs. Morbidity and mortality estimates are critical to inform policy decision on vaccine development with implications for determination of clinical trials vaccine efficacy assessments.