Worms, diseases that affect billions of people in the world, have few advances in clinical studies. Among the reasons for this to occur is the fact that they reach poorer populations, not attracting investments from pharmaceutical companies. The warning is in a study published in the Drug Discovery Today magazine by researchers from the University of São Paulo (USP) and the Guarulhos University, which has the support of the São Paulo Research Foundation (FAPESP).
The work is part of a context in which the World Health Organization (WHO) launched, in 2021, an action plan to eradicate or control, by 2030, 20 diseases that affect one in five people in the world and kill about 500 thousand a year. Of the 20 diseases, the five that most affect the most people in absolute numbers are worms. One of the strategies adopted in the search for new drugs is pharmacological repositioning, studying existing medications for these neglected diseases.
“Among the multiple goals that have been placed on the WHO roadmap is the search for new drugs, because many of these diseases do not have a vaccine and a drug considered to be highly effective. Although it has a relatively good efficacy, but not enough to control the disease, not least because there is no 100% effective drug”, says Josué de Moraes, who coordinates the Nucleus for Research in Neglected Diseases (NPDN) at the Guarulhos University, one of the article authors.
schistosomiasis
Moraes cites, as an example, the case of schistosomiasis, which is considered the main worm in terms of morbidity and mortality. “While ascariasis, which is roundworm, affects a larger share, almost a billion people, schistosomiasis has the most impact on health,” he explains. There is only one drug available for the disease, praziquantel. “Imagine having a drug for a population of over 200 million”, he compares. In addition, the drug also does not affect the young form of the parasite, preventing treatment from starting early in the infection.
The researcher highlights, among the impacts of worms, the fact that they impair the intellectual development of children, contribute to a reduction in the schooling rate and can also cause the person to take sick leave from work. “I always say that these diseases not only prevail in conditions of poverty, but also represent a strong obstacle to the development of countries and, consequently, are decisive in the maintenance of inequality”, he evaluates.
Among the reasons that prevent the development of studies in the field of parasitology, Moraes cites four. “Verminoses are the most neglected among the neglected ones, mainly because it is a type of disease that is more associated with the issue of poverty than the others”, he points out, as the first obstacle. He also points out the fact that the disease does not give rise to a sense of urgency. “They do not visibly demonstrate that there is a need for the population.” He recalls that in some regions, worms are even seen as something common, everyday.
Another difficulty occurs in the laboratories. “Worms are difficult to maintain. It is much more difficult to keep a worm in the laboratory, unlike some diseases caused by protozoa, such as malaria, leishmaniasis, Chagas disease, among others”, he exemplifies. This ends up harming the biological knowledge of the worms. “When available, you need to have the definitive host, usually we use a rodent and an intermediate host, in the case of schistosomiasis, a snail.” Moraes also highlights the disgust that worms arouse in individuals.
The researcher is emphatic in recalling that other public health measures, such as diagnosis, control of transmission vectors and universal basic sanitation, are essential to deal with these diseases. “We have about 30 million Brazilians who live without treated water. Practically half of the population does not have access to sewage. So this reinforces this picture, which I would say regrettable, in relation to verminoses”, he evaluates.