Schistosoma Vaccine Candidate Enters Phase Ib Clinical Trial

A new clinical trial for a Schistosomiasis vaccine candidate will be conducted in Brazil, where it is endemic.

Most people are unaware that Schistosomiasis is the second most deadly parasitic disease, following malaria.

Schistosomiasis afflicted more than 206 million people worldwide in 2016, out of which more than 88 million people were reported to have been treated, reports the WHO.

The vaccine target in this phase 2b clinical study is the intestinal/liver schistosomiasis caused by Schistosoma mansoni, one of two species that accounts for approximately one-third of the total number of schistosomiasis cases, including all of the cases occurring in the Americas.

The Sm-TSP-2 antigen was selected as the lead candidate to target the disease caused by S. mansoni.

Schistosomiasis, also known as snail fever or bilharzia, is a disease caused by parasitic flatworms in sub-Saharan Africa and Latin America, says the Centers for Disease Control and Prevention (CDC).

People become infected when larval forms of the parasite – released by freshwater snails – penetrate the skin during contact with infested water.

Transmission occurs when people suffering from schistosomiasis contaminate freshwater sources with their excreta containing parasite eggs, which hatch in water.

“Right now, people are treated for schistosomiasis only to be rapidly reinfected. Creating a vaccine is critical to stopping this cycle,” said Dr. David Diemert, principal investigator and associate professor of microbiology, immunology, and tropical medicine at the George Washington University School of Medicine and Health Sciences.

Researchers at Baylor College of Medicine, in collaboration with a team of researchers at the George Washington University and the René Rachou Institute, will lead this study.

Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, said “Schistosomiasis ranks among the most devastating poverty-related neglected diseases - and a schistosomiasis vaccine would be a game changer both for global public health and poverty reduction.”

The first clinical study to examine the vaccine’s safety and immunogenicity was conducted at the Baylor College of Medicine Vaccine Treatment and Evaluation Unit in 2015.

“The main purpose of this new study is to assess the vaccine safety in a group of healthy adults who may have previously been exposed to schistosomiasis,” said Dr. Robert Atmar, professor of infectious diseases at Baylor and co-principal investigator of the trial.

“The investigative team will also evaluate the ability of different doses of the vaccine with or without adjuvant to induce antibody and cellular immune responses to the vaccine agent.”

The vaccine was developed by a consortium of partners, led by Texas Children’s Hospital Center for Vaccine Development.