American cutaneous leishmaniasis (ACL) is a major public health problem caused by
vector-borne protozoan intracellular parasites from the genus Leishmania, subgenera
Viannia and Leishmania. Asymptomatic infection is the most common outcome after
Leishmania inoculation. There is incomplete knowledge of the biological processes
explaining the absence of signs or symptoms in most cases while other cases present a
variety of clinical findings. Most studies of asymptomatic infection have been
conducted in areas of endemic visceral leishmaniasis. In contrast, asymptomatic ACL
infection has been neglected. This review is focused on the following: (1)
epidemiological studies supporting the existence of asymptomatic ACL infection and
(2) immunological studies conducted to understand the mechanisms responsible for
controlling the parasite and avoiding tissue damage.