Second autochthonous case of kala-azar is confirmed in Florianópolis

Publicação: 7 de November de 2017

Expert acknowledges human visceral leishmaniasis urbanization trend

Controlling visceral leishmaniasis (canine and human) requires an integrated effort by public health and epidemiological surveillance organs as well as the population

After confirming three kala-azar cases (human visceral leishmaniasis) in Porto Alegre (RS), the Epidemiological Surveillance from Florianopolis, Santa Catarina, neighbor state, confirmed the second autochthonous case of the disease on September 13. According to the professor at the Microbiology, Immunology and Parasitology Department at the Federal University of Santa Catarina (UFSC), Mario Steindel, the expansion of the leishmaniasis has been observed for the past decades. Still according to him, most recently an urbanization trend of the disease has also been observed. This derives from several factors, related to anthropic activities (deforestation, building houses in wild vegetation borders, uncontrolled urban expansion, etc.), besides possible effects in consequence of climate change.

Knowing that leishmaniasis is present in Brazil since the 1950s and that the insecticide used to control Aedes aegypti, dengue transmitter, is not effective against the sandfly, until the moment an insecticide able to combat leishmaniasis has not been developed. “The Aedes aegypti is an urban mosquito, while the sandfly is usually found in forests or in their borders. This precludes the use of the same well-established control strategy used for the Aedes. Besides this, the sandfly has a very distinct biology, since its breeding sites are difficult to identify and, usually, are related to organic matter decomposition. It is not that the sandfly is resistant to the insecticide used to control Aedes, but due to differences in the insect’s biology the Aedes control strategy does not apply to the sandfly”, he explains.

After the first case of human visceral leishmaniasis in Santa Catarina, reported in Florianopolis in early August, the City Health Secretary performed tests in the place where the 53 year-old man was infected. Among the 99 examined dogs, over 10 were confirmed to have canine visceral leishmaniasis. Doctor Steindel stresses that controlling human and canine leishmaniasis requires an integrated effort by health organs, epidemiological surveillance and the population as well. The latter must be informed and clarified about this severe health problem of difficult control. Dog sacrifice as an isolated measure is little effective, since the animal reposition is very frequent and keeps the transmission cycle active. Each one must do their bit.

In Porto Alegre, for example, the Surveillance estimated the distance of 2.5 km from the forest to keep dogs. This measure is explained by the fact that the sandfly has a very limited flight capacity. However, it is important to stress that even in urban areas, with garbage buildup and presence of vegetation could become sandfly breeding sites. Besides this, females must feed on blood to produce eggs. Insects, generally, feed on birds, and for this reason, a chicken house could become a risk factor for sandfly reproduction. Chicken are completely refractory to the parasite, but if an infected dog and a large number of sandflies are present, the risk of transmission to humans increases very much.

The anti-Leishmania dog collar is the most effective method to control the disease among these animals. “The collars protect the animals. The problem is their durability ranges from three to 6 months depending on the brand and type of insecticide. The efficiency decreases with time. Similarly, contact with rain of baths also reduce the collar’s protection”, stresses Dr. Steindel while adding that using the collar from the beginning, certainly causes a positive impact, but it is necessary to follow up and replace whenever needed. This action must be very well organized in order to return the expected results.

It is worth reminding that there is already an animal-use drug registered at the Agriculture and Livestock Ministry (MAPA) to treat dogs with CVL, the Milteforan®. However, financially speaking, in the current scenario it is little likely that the Health Secretaries will supply owners with the drug, making their obligation to acquire and treat their animals.

“Visceral leishmaniasis can be considered the new “nightmare” for public health over the next decades. Health professionals should include visceral leishmaniasis in differential diagnostic for patients with fever, thinning and visceromegaly. The vaccine for dogs already approved by the MAPA must be used in scale. The diagnostic tests for dogs should be enhanced as well as the cases notification”, adverts the professor. According to him, animals should be monitored by skilled professionals and the dog’s owner should take full responsibility for the animal’s health. “We must collude these actions between Government through its health organs, research laboratories, epidemiological surveillance, veterinary hospitals and the population. The challenge is immense and we will only succeed with shared efforts”, he finishes.…