**3. Visceral leishmaniasis**

#### **3.1. Epidemiology**

VL is recognized by the World Health Organization (WHO) as one of the most important zoonoses, due to its high incidence and mortality. Every year about 500,000 new cases of VL are reported, with 40,000–50,000 deaths worldwide [20]. The disease is endemic in 65 countries, including Bangladesh, India, Brazil, Nepal, Ethiopia and Sudan. In Latin America, VL is pres‐ ent in 12 countries and is caused by the protozoan *Leishmania (L.) infantum chagasi*, with 90% of the cases being reported in Brazil, especially in the Northeast and Southeast regions, rep‐ resenting a significant public health concern [3, 21]. In Brazil, the average number of cases of VL increased from 2866 in 1990–2000 to 3353 in 2001–2014 [22], with a fatality rate of about 7% in 2014 [23].

The disease has shown significant changes in the pattern of transmission, initially with a predominantly rural distribution, which fly has expanded to peri‐urban and large urban areas [20, 24]. Although the main route of transmission is associated to hematophagous sand‐ fly vectors, there are other routes which are important to be reported, including sexual, verti‐ cal and hematogenic [16].

Although the infection can affect people of all ages, in endemic areas, most reported cases are children below 10 years old. This is probably due to their immunological immaturity aggravated by malnutrition, which is common in these areas [3, 20]. Over 60% of the affected people are males [21, 25].
