Abstract
The northern region of Brazil, which has the largest number of cases of tegumentary leishmaniasis (TL) in the country, is also the region that has the highest diversity of species of vectors and Leishmania parasites. In this region, cases of mucosal leishmaniasis (ML), a clinical form of TL, exceed the national average of cases, reaching up to 12% of the total annual TL notifications. ML is associated with multiple factors, such as the parasite species and the viral endosymbiont Leishmania RNA virus 1 (LRV1). Being a chronic parasitological disease, laboratory diagnosis of ML poses a challenge for health services. Here, we evaluated more than 700 clinical samples from patients with clinical suspicion of TL, including patients with cutaneous leishmaniasis (CL) and mucosal leishmaniasis, comparing the results of parasitological tests—direct parasitological examination by microscopy (DP) and conventional PCR (cPCR) targeting of both kDNA and hsp70. The DP was performed by collecting material from lesions through biopsies (mucosal lesions) or scarification (cutaneous lesions); for PCR, a cervical brush was used for sample collection. Blood samples were tested employing standardized real-time PCR (qPCR) protocol targeting the HSP70 gene. PCR tests showed higher sensitivity than DP for both CL and ML samples. Considering ML samples only (N = 89), DP showed a sensitivity of 49.4% (N = 44) against 98.8% (N = 88) for kDNA PCR. The qPCR hsp70 for blood samples from patients with ML (N = 14) resulted in superior sensitivity (50%; N = 7) compared to DP (21.4%; N = 3) for samples from the same patients. Our results reinforced the need to implement a molecular test for the diagnosis of ML, in addition to proposing methods less invasive for collecting material from TL patients. Sample collection using a cervical brush in lesions observed in CL and ML patients is easy to perform and less invasive, compared to scarification and biopsies. Blood samples could be a good source for qPCR diagnosis for ML patients. Thus, we propose here a standardized method for collection and for performing of molecular diagnosis of clinical samples from suspicious ML patients that can be applied in reference services for improving ML diagnosis.
Highlights
Tegumentary leishmaniasis (TL) is an endemic disease, with an estimated 600,000 to 1 million new cases occurring globally each year, with the highest concentration in America, the Mediterranean basin, the Middle East, and Central Asia
We investigated 723 cases with clinical suspicion of tegumentary leishmaniasis (TL) and performed the three parasitological tests—a direct parasitological test (DP) and two polymerase chain reaction (PCR)-based tests, kinetoplast DNA (kDNA) and hsp70 PCR
One hundred twenty-three patients presented mucosal lesions and 72.4% were confirmed with Leishmania spp. infection, but only 36% were confirmed based on DP
Summary
Tegumentary leishmaniasis (TL) is an endemic disease, with an estimated 600,000 to 1 million new cases occurring globally each year, with the highest concentration in America, the Mediterranean basin, the Middle East, and Central Asia. In Brazil, it is endemic throughout the territory and Brazil was among the few countries responsible for about 90% of the new cases of TL in 2019 [1,2]. In CL, the most common clinical form is the localized lesion. ML is a clinical evolution of the CL form where the late mucosal lesion appears after a CL event [6,7]. The parasite is transmitted to the vertebrate host by the bite of the infected female phlebotomine insect during the blood meal. Different species of Leishmania parasite can cause the infection. For workers involved in activities related to environmental changes, such as deforestation, construction of dams, and activities in the field, such as agriculture, mining, and farming, the chances of acquiring infection are increased [2]
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