Brazil is just a few steps away from producing the world’s first vaccine against schistosomiasis, a worm-borne disease that causes large, swollen bellies in children and adults in the poorest regions of the southern hemisphere, particularly Africa. The discovery is the work of a team from the Oswaldo Cruz Foundation, a public body based in Rio de Janeiro.
Preclinical testing of the vaccine, dubbed Shistovac (sm14), in laboratory animals has reduced Schistosoma masnoni infection by more than 90% of that in mice and rabbits. In humans, the vaccine proved safe, its main side effect was pain in the area of application. The researcher, who has led the team that developed the vaccine for years, Miriam Tendler, explains over the phone that the results are “outstanding from phase one”.
It is the most socio-economically devastating parasitic disease in the world after malaria.
Researchers are currently completing the final phase of human testing and are working to have the World Health Organization (WHO) issue the required certificate. After being tested on 300 people in Brazil in recent years, it is now set to be tested on a further 2,000 people in Senegal. If all goes well, the vaccine will be the world’s first to protect against a worm. Vaccine studies began in the 1980s with the aim of protecting cattle from parasitic infections. After decades of lack of industry interest in developed countries and a few failed attempts, the launch of the immunization agent could begin in late 2025 or early 2026, Tendler estimates.
The disease, popularly known as “water belly” in Brazil, is closely linked to poor sanitation and the lack of sanitation and drinking water, which is why it mainly affects the poorest countries. Infection occurs through the larvae of the parasitic snail eggs, which penetrate human skin. The larvae already transform in the blood and settle in organs such as the liver. The adult worms can end up in the veins of the intestine or bladder, where they form the characteristic bloated abdomen.
The vaccine contains the Sm14 protein, which is present in the schistosoma. These proteins are vital as they carry the necessary fats that guarantee the parasite’s survival. But the vaccine protein is modified and prevents the transport of these fats and thus prevents the parasite from multiplying. The discovery could dramatically change the landscape in dozens of countries where the disease is currently being treated with drugs. Although the mortality rate is low, schistosomiasis causes a great loss of quality of life. For example, it impairs the learning process of children at school or the work performance of young adults, explains the researcher.
The disease is closely linked to poor sanitation and lack of sanitation and drinking water, which is why it mostly affects the poorest countries
The WHO estimates that 200 million people contract the disease each year, with another 800 million living in high-risk areas. In Africa it is represented in 74 countries. In Latin America, 95% of cases are concentrated in Brazil. Globally, it is the most socio-economically devastating parasitic disease after malaria.
The vaccine is the result of an alliance between the Oswaldo Cruz Foundation and the American company Orygen Biotechnology, but was developed entirely in Brazil. Tendler proudly emphasizes that all of the technology used is Brazilian, as are the patents. The researcher emphasizes that Brazil does not have the financial means for research in Europe or the USA, but has a much deeper knowledge of tropical and parasitic diseases. In his opinion, it will be an iconic vaccine: “It’s a sophisticated vaccine and it breaks a paradigm that endures to this day.” We hope it paves the way for other antiparasitic vaccines that go unnoticed by big industry , as there is no market in the countries of the northern hemisphere and therefore they are not on their list of priorities,” he points out. Organizations involved in developing the vaccine have pledged to commercialize it at a low cost so it can get to where it’s needed most. It will match what the WHO defines as a “humanitarian” vaccine.
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