Visceral leishmaniasis (VL) is a disease caused by a microscopic parasite called Leishmania chagasi, which is mainly found in tropical and subtropical areas. It is a chronic, systemic disease that affects both dogs and humans, mainly children under the age of five. According to the Pan American Health Organization, an average of 3,500 cases are recorded each year with a fatality rate of 7%.
Infection occurs through the bite of a flying insect called a sandfly that acts as a carrier of the Leishmania parasite. These insects develop in organic matter and require a dark, humid and cool environment to reproduce. It is during the evening and at night that both humans and animals tend to bite.
In urban areas, the dog harbors this parasite, on the other hand, in the main jungle reservoirs are foxes and marsupials.
The incubation period is between 10 days and 24 months, however, most often it is from two weeks to two months. The infection is characterized by a broad clinical spectrum, which can range from mild to moderate and severe clinical manifestations.
The classic symptoms of VL are fever, which can be constant or irregular, enlargement of the spleen, liver, pallor caused by severe anemia, and slow and progressive weight loss. Other secondary signs and symptoms include respiratory or gastrointestinal disorders, such as vomiting and diarrhea. In severe cases there is malnutrition and edema in the lower limbs. It should be noted that if adequate treatment is not provided in time, it can lead to death.
Dogs can harbor the parasite throughout their lives. Among the most common symptoms they experience are skin lesions, dull coat, excessive nail growth, thinning, irregular fever, enlarged liver and spleen, widespread inflammation of nodes and anemia.
The diagnosis is made by immunological and parasitological tests. With regard to treatment, there are several drugs to treat the disease. However, the choice of it should consider the clinical and laboratory conditions of patients, the presence of co-infections and pregnancy. So far there is no vaccine or medicine to prevent infection, but preventive measures can be taken.
The recommended measures for human protection are to reduce contact with vectors, including avoiding outdoor activities from dusk to dawn; the use of mosquito nets; the use of protective clothing and insect repellents. People with clinical manifestations of the disease should be treated as early as possible.
Regarding pets, the director of the Companion Animal Business Unit of MSD Animal Health in Southern Region, Walter Comas, provided some recommendations for taking care of this disease, such as using pipettes with a repellent and insecticidal effect, collars and preventing dogs from being outdoors at night.
On the other hand, the hygiene of spaces and fumigating, both indoors and outdoors, is essential. Keep yards and gardens clean, remove organic matter, such as leaves, collect animal fecal matter and waste. It is also suggested to place fine-mesh mosquito nets on doors and windows and in kennels. People should always use repellent.
The disease has been detected in 13 countries in the region, including Argentina, Bolivia, Brazil, Colombia, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Paraguay, Uruguay and Venezuela. In our country it was found in the provinces of Misiones, Corrientes, Formosa, Santiago del Estero and Entre Ríos.
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