Characterization of the Infectious Agent Causing Tegumentary Leishmaniasis in Peru
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Leishmaniasis is a parasitic disease most commonly manifested as cutaneous lesions that occur on exposed areas of skin. The lesions begin as red papules that grow to form a painless ulcer associated with granulomatous tissue at the base, surrounded by raised margins. It is estimated that 12 million people worldwide are infected with the disease, and an additional 2 million are diagnosed each year, with 1/10 of the world population at risk of infection. There are 20 species of Leishmania pathogenic to humans and an estimated 30 species of sandfly that serve as vectors. In the endemic country of Peru the main causative Leishmania species is not certain. We aimed to collect data from patients with tegumentary and mucosal leishmaniasis and perform nested Real-Time PCR to determine the species of the causative agent. We also aimed to collect the vector in the field and identify which sandfly species are carrying the parasite and which species of Leishmania the sandfly is infected with. Individuals who were suspected of having cutaneous or mucocutaneous leishmaniasis were referred to a study site to have a tissue sample taken of their lesion. Three tissue samples were collected: a lancet scraping, a filter paper impression, and a tissue aspiration. Lancet scraping was performed by first disinfecting the lesion, then obtaining tissue secretions from the inside border. Filter paper was performed by disinfecting the lesion and pressing the filter paper on the lesion, thus collecting the fluids. Aspiration was performed by disinfecting the lesion, and a needle containing a sterile saline solution with antibiotics was inserted on the outside border and base, and then rotated. The fluid collected was then placed in a tube with Senekjie's rabbit blood agar. Of the patients with suspected leishmaniasis, the causative agents were L braziliensis, L guyanensis, L laisoni, and some species that could not be identified. L braziliensis was the majority of the species in the positively identified cases, as well as being nearly all of the cases of mucocutaneous leishmaniasis. Patients receiving treatment after testing positive are being followed to determine clinical presentations during treatment and any resistance each specific species may show. In the future, the cultures will then be used to help determine the mechanism of resistance to help better administer treatment. We also propose to develop a sensitive and specific diagnostic test that can be deployed in areas without additional equipment by using a technique called recombinase polymerase amplification (RPA).