What’s Eating You? Phlebotomine Sandflies and Leishmania Parasites
Phlebotomine sandflies of the Phlebotomus and Lutzomyia genera are vectors for the spread of Leishmania parasites. Leishmaniasis is a parasitic infection most common in the Middle East and Central and South America. Few cases have been reported in the United States, with most patients presenting after returning from travel to other countries; however, the parasite has been locally acquired in Texas and Oklahoma. Clinical presentation varies depending on the species of Leishmania. There are 4 general clinical classifications of leishmaniasis: cutaneous, diffuse cutaneous, mucocutaneous, and visceral.
Practice Points
- The Phlebotomus and Lutzomyia genera of sandflies are vectors of Leishmania parasites, which can result in an array of clinical findings associated with leishmaniasis.
- Treatment options for leishmaniasis differ based on whether the infection is considered uncomplicated or complicated, which depends on the species of Leishmania; the number, size, and location of the lesion(s); and host immune status.
- All US practitioners should be aware of this pathogen, especially with regard to patients who have a history of travel to other countries. Health care professionals in states such as Texas and Oklahoma should be especially cognizant because these constitute one of the few areas in the United States where locally acquired cases of leishmaniasis have been reported.
Prevention—Vector control is the primary means of preventing leishmaniasis under 2 umbrellas: environmental management and synthetic insecticides. The goal of environmental management is to eliminate the phlebotomine sandfly habitat; this was the primary method of vector control until 1940. Until that time, tree stumps were removed, indoor cracks and crevices were filled to prevent sandfly emergence, and areas around animal shelters were cleaned. These methods were highly dependent on community awareness and involvement; today, they can be combined with synthetic insecticides to offer maximum protection.
Synthetic insecticides include indoor sprays, treated nets, repellents, and impregnated dog collars, all of which control sandflies. However, the use of these insecticides in endemic areas, such as India, has driven development of insecticide resistance in many sandfly vector species.3
As of 2020, 5 vaccines against Leishmania have been created. Two are approved–one in Brazil and one in Uzbekistan–for human use as immunotherapy, while the other 3 have been developed to immunize dogs in Brazil. However, the effectiveness of these vaccines is under debate. First, one of the vaccines used as immunotherapy for cutaneous leishmaniasis must be used in combination with conventional chemotherapy; second, long-term effects of the canine vaccine are unknown.1 A preventive vaccine for humans is under development.1,3
Final Thoughts
Leishmaniasis remains a notable parasitic disease that is increasing in prevalence worldwide. Clinicians should be aware of this disease because early detection and treatment are essential to control infection.3 Health care providers in the United States should be especially aware of this condition among patients who have a history of travel or migration; those in Texas should recognize the current endemic status of leishmaniasis there.4,6
