Shigella

Shigella is a highly invasive bacterium that can cause severe dysentery and bloodstream infections. The infection it causes, called shigellosis, can lead to long-term health complications, cognitive impairment, and even death. The infections are frequently linked to conditions of poverty, malnutrition, inadequate sanitation, and unsafe drinking water.

As a major cause of diarrheal disease-related deaths, Shigella accounts for 80-165 million cases and 600,000 deaths annually, with the highest incidence rates among children under 5 years old. Sub-Saharan Africa and South Asia are the regions with the highest incidence rates.

There are currently no licensed Shigella vaccines available for global use. Antimicrobial resistance is a serious obstacle to treating Shigella, which is becoming increasingly resistant to antibiotics. In the near future, vaccines may be the only tools available to prevent Shigella-related deaths.

IVI’s work on Shigella

To accelerate the development of a Shigella vaccine, the International Vaccine Institute is conducting preclinical development of novel Shigella vaccines and surveillance and disease burden studies in Asia and Africa in collaboration with partners.

Through these initiatives, IVI aims to develop effective vaccines and strategies to combat Shigella, addressing a significant public health challenge in the world’s vulnerable populations.

Shigella Conjugate Vaccine (SCV4) development

In 2023, IVI joined a consortium with Massachusetts General Hospital, Harvard University, and Tulane University to jointly develop a quadrivalent Shigella conjugate vaccine targeting Shigella flexneri 2a, 3a, 6 and S. sonnei. The consortium’s goal is to develop the manufacturing process to produce a vaccine and support eventual technology transfer to a manufacturer. In 2024, IVI began cell bank preparation and establishing process development and manufacturing techniques.

Assay development for combination vaccines against gastrointestinal infections

Launched in 2024 at the request of the Ministry of Food and Drug Safety of the Republic of Korea, this project studies the feasibility of a combination vaccine against rotavirus, Shigella and Salmonella Typhi—major gastrointestinal pathogens which pose a significant burden for children in low- and middle-income countries. This study will develop a combination vaccine against these pathogens and immunogenicity assays for testing the vaccine.

Estimating the Burden of Shigella in Nepal

IVI’s prospective surveillance study will estimate the burden of shigellosis in Nepal in children under 5. By generating data on the proportion of cases, disease severity, antimicrobial resistance, and serotype distribution among children with diarrhea in the country, this study will help funders, public health officials, and policymakers allocate resources effectively and promote the development of vaccines and other strategies to control shigellosis.

Shigella surveillance in Ghana

This study aims to determine the incidence of Shigella-attributed medically attended diarrhea (SMAD) in young children using the stool/rectal swab culture-based method. It will also assess linear growth faltering in the six months following an episode of SMAD compared with the control group. Additionally, the study will examine the clinical characteristics and complications of SMAD at time of presentation to health care facilities and after illness along with assessing the incidence of SMAD by serotypes, age groups, and seasons. Another objective is to help estimate the prevalence of resistance to commonly used antibiotics among the isolated Shigella strain.

Page updated: March 2025