NIH-funded researchers start Shigella vaccine trial

Researchers funded by the National Institutes of Health recently began an early-stage human clinical trial of two related candidate vaccines to prevent infection with Shigella bacteria.

Shigella infection, known as shigellosis, is an intestinal disease spread by contact with infected feces, by contact with a contaminated surface, or by consumption of contaminated food or water. Symptoms include diarrhea, abdominal pain, vomiting, nausea and fever. The disease can lead to hospitalization or death, particularly in young children and adults with weakened immune systems.

The Phase I clinical trial will evaluate the vaccines for safety and their ability to induce immune responses among 90 healthy adults between the ages of 18 and 45.

"It seems that Shigella bacteria know our immune system better than we do," William Alexander, a program officer in NIAID's Enteric and Hepatic Diseases Branch, Division of Microbiology and Infectious Diseases, said. "They've become very good at evading the human immune response and causing significant illness, so developing vaccines and better treatments is critical."

The two related candidate vaccines, WRSs2 and WRSs3, were found to be safe and effective when tested in guinea pigs and non-human primates. The vaccine candidates look to improve on WRSs1, which was found to cause mild diarrhea in some patients. All three vaccines were developed by researchers at the Walter Reed Institute.

Shigellosis causes approximately 90 million cases of severe disease annually and 108,000 deaths worldwide, according to the World Health Organization. The U.S. reports 14,000 shigellosis cases each year, most occurring among children ages one to four years old.

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