EXPRESS: First molecular detection of Leishmania infantum in a domestic cat from Costa Rica: a case report

Leishmaniasis is a disease caused by microscopic parasites that can affect both people and animals. Dogs are the most affected domestic animals, but cats can also become infected. Until now, this parasite had never been confirmed in a domestic cat in Costa Rica using advanced molecular tests. In this case, a pet cat was taken to a veterinary clinic because the owner noticed a small, painless lump on one of its back legs. The cat seemed otherwise healthy. Blood tests ruled out viral diseases that weaken the immune system in cats. Ultrasound examination showed enlarged lymph nodes and spleen, which suggested possible internal involvement. A small sample taken from the lump showed cells containing structures compatible with the parasite. The mass was surgically removed and analyzed using molecular techniques that detect the parasite’s genetic material. These tests confirmed the presence of Leishmania (L.) infantum. Surprisingly, the removed tissue showed only inflammation and no visible parasites under the microscope. After surgery, the cat did not receive antiparasitic treatment. Seven months later, the cat remained completely healthy, and the lump did not return. This suggests that some cats may be able to control the infection naturally. This case is important because it shows that this parasite is still present in Costa Rica, even in areas where it had not been detected for many years. It also highlights the need for veterinarians to consider leishmaniasis as a possible cause of skin lumps in cats, even when the animal appears healthy.