Dynamics of American tegumentary leishmaniasis in a highly endemic region for Leishmania (Viannia) braziliensis infection in northeast Brazil

Abstract

BackgroundAmerican Tegumentary Leishmaniasis (ATL) caused by Leishmania braziliensis is endemic in Corte de Pedra, Northeast Brazil. Most L. braziliensis infections manifest as localized cutaneous leishmaniasis (CL). Disseminated manifestations include mucosal leishmaniasis (ML), present at a low constant level for several decades, and newly emerging disseminated leishmaniasis (DL). Surprisingly, DL has recently surpassed ML in its spatial distribution. This led us to hypothesize that distinct forms of ATL might spread in different patterns through affected regions.Methodology/Principal findingsWe explored the incidence and geographic dispersion of the three clinical types of ATL over a span of nearly two decades in Corte de Pedra. We obtained the geographic coordinates of the homes of patients with ATL during 1992–1996, 1999–2003 and 2008–2011. The progressive dispersion of ML or DL in each time period was compared to that of CL in 2008–2011 with the Cusick and Edward’s geostatistical test. To evaluate whether ATL occurred as clusters, we compared each new case in 2008–2011 with the frequency of and distance from cases in the previous 3 to 12 months. The study revealed that DL, ML and CL actively spread within that region, but in distinct patterns. Whereas CL and DL propagated in clusters, ML occurred as sporadic cases. DL had a wider distribution than ML until 2003, but by 2011 both forms were distributed equally in Corte de Pedra. The incidence of ML fluctuated over time at a rate that was distinct from those of CL and DL.Conclusions/SignificanceThese findings suggest that CL and DL maintain endemic levels through successive outbreaks of cases. The sporadic pattern of ML cases may reflect the long and variable latency before infected patients develop clinically detectable mucosal involvement. Intimate knowledge of the geographic distribution of leishmaniasis and how it propagates within foci of active transmission may guide approaches to disease control.

Profile of American tegumentary leishmaniasis in transmission areas in the state of Minas Gerais, Brazil, from 2007 to 2017

“…and Lutzomyia spp., belonging to the family Psychodidae (subfamily Phlebotominae), act as vectors for Leishmania in the Americas and play an important role in disease dissemination among humans and domestic animal reservoirs [3][4][5]. In Brazil and South America, the major agent causing ATL is the Leishmania (Viannia) braziliensis [6].…”

Leishmaniasis cutánea inducida por especies de Leishmania Viannia en ratones BALB/c y eficacia de un tratamiento tópico

“…La leishmaniasis del Nuevo Mundo (leishmaniasis tegumentaria americana) es multiforme en sus manifestaciones clínicas (de lesiones cutáneas localizadas a formas diseminadas y/o formas destructivas de las mucosas) [5][6][7] . Las lesiones cutáneas generalmente son indoloras y crónicas auto-limitadas afectando principalmente zonas expuestas a los vectores como la cara y extremidades.…”

“…El perfil inflamatorio revela la predominancia de macrófagos, linfocitos en la unión epidermis-dermis, algunos granulomas y áreas con necrosis. También se observan células plasmáticas, células gigantes y vasculitis [6][7][8] . La LC producida por L. (V.) braziliensis ha mostrado lesiones nodulares eritematosas, induradas con ulceración central y presencia de exudado 6 .…”

“…También se observan células plasmáticas, células gigantes y vasculitis [6][7][8] . La LC producida por L. (V.) braziliensis ha mostrado lesiones nodulares eritematosas, induradas con ulceración central y presencia de exudado 6 . Microscópicamente se observa infiltrado dérmico inflamatorio mixto superficial con presencia de linfocitos, células plasmáticas, histiocitos y células epiteliodes con epidermis ulcerada superpuesta, encontrándose macrófagos parasitados con amastigotes [6][7] .…”

“…La LC producida por L. (V.) braziliensis ha mostrado lesiones nodulares eritematosas, induradas con ulceración central y presencia de exudado 6 . Microscópicamente se observa infiltrado dérmico inflamatorio mixto superficial con presencia de linfocitos, células plasmáticas, histiocitos y células epiteliodes con epidermis ulcerada superpuesta, encontrándose macrófagos parasitados con amastigotes [6][7] . Las diferencias clínicas e histopatológicas entre la infección con L.(V.) panamensis vs L.(V.) braziliensis en el modelo murino, podrían estar involucradas en la respuesta a los tratamientos tópicos.…”