Visceral leishmaniasis in Brazil: where are we going?

Publicação: 12 de December de 2017

Doctor Guilherme Werneck, in a paper, alerts to the fact that recent news of autochthonous human cases are “the tip of the iceberg” in the disease’s dissemination process to the entire country seems inexorable

The goal to eliminate VL along with the public health problem in Brazil is audacious, but should not be considered impossible

Researcher Guilherme Werneck, PhD in Public Health from Harvard School of Public Health, member of the WHO Expert Advisory Panel on Parasitic Diseases (Leishmaniasis), has developed during his career activities in the field of Collective Health, with emphasis in Epidemiology, and his researches mainly include the following themes: infectious diseases epidemiology, epidemiological methods, visceral leishmaniasis epidemiology and control, spatial data analysis, biostatistics, violence epidemiology. In this exclusive article written for the BSTM, he alerts to the severity of the visceral leishmaniasis expansion situation.

Visceral leishmaniasis (VL) is a tropical neglected disease of great relevance in the world, affecting mostly sidelined populations and contributing to perpetuate the poverty and social exclusion cycles. Despite the great recent advances controlling VL in India, the area that concentrated over 2/3 of the world cases until the year 2000, from 50 to 100 thousand cases are reported every year worldwide and 90% of them are concentrated in seven countries: Brazil, Ethiopia, India, Kenya, Somalia, Sudan and South Sudan.

In Brazil, the leading thought is that transmission is essentially zoonotic, the domestic dog is the main urban reservoir and the Lutzomyia longipalpis sand fly is the vector with greater epidemiological importance. Based on these assumptions, the VL control program was established by the Presidential Decree 51.838 from March 3, 1963, emphasizing the early diagnosis and treatment of human cases, the reduction of sand fly population and elimination of infected reservoirs. Still today, these are the pillars that drive the Visceral Leishmaniasis Control Program (VLCP) from the Health Ministry.

Notwithstanding the efforts towards optimizing the control actions, the evidences point to its failure. From a disease once restricted to the Country’s rural areas, the VL urbanization process, started in the 1980s and deepened in the next decades, culminating with the permanent installation of VL in large cities. Successful local VL control experiences have been widely replaced by daily observation of new cases in previously harmless areas. The recent news of autochthonous human cases in Porto Alegre (RS) and Florianópolis (SC) are the “tip of the iceberg” of a transmission cycle established years ago and the numerous efforts containing it only confirm the disease’s dissemination process to the entire country seems to be inexorable.

For years, the researchers and managers’ attention was aimed mainly in assessing the effectivity and identification of new strategies to reduce VL transmission. Usually, the results of these efforts evidence that vector control actions by residual insecticide action and serologically positive dog culling, despite logical from a theoretical point of view, face great logistic-operational troubles, making them insufficient to contain the disease. Including new approaches in the available actions arsenal, as dog treatment and use of insecticide collars, could be an alternative, but these strategies still need to be assessed for cost-effectiveness before eventually being incorporated in large scale.

It is time to change, but there are no “silver bullets”. It urges that the scientific community associate to health professionals, managers and the civil society to create solid knowledge on how to approach the problem in an integrated way. Only once free of their interests and beliefs, it will be possible to achieve an agreement that creates recommendations based on the best available evidences and that adjust to different local realities, considering not only transmission rates, but also historical, geographical, social and health services organizations in each city as well as all ethical aspects related to all community intervention. In order for this process to evolve, we must incorporate active community participation, not as mere observers, but as authors and key players.

Today, actions to reduce the disease’s lethality should be prioritized, not only for their relevance, but also for a greater feasibility to achieve them if compared to transmission reduction. In this sense, enhancing VL patients’ access and care should be a major goal. The goal to eliminate VL with Brazil’s public health problem is audacious, but should not be considered impossible. However, we must not lose sight that this battle will only be won with the strengthening of the Unified Health System and the reduction of social inequalities.…