Leishmania mexicana
Encyclopedia
Leishmania mexicana is a Leishmania
species.
It is associated with leishmaniasis
.
Leishmania mexicana is an obligate intracellular protozoan parasite that causes a less dangerous form of leishmeniasis. Given its name, this parasitic form occurs in South and Central America. Infection of L. mexicana occurs when an individual is bitten by an infected sand fly that injects the infective promastigotes, which are carried in the proboscis, directly in the skin.
The life cycle of this and other Leishmania species are similar and begin when an infected fly bites and injects it promastigotes in the skin of host and once inside these promastigotes are phagocytosed by macrophages that transform into amastigotes and are able to divide. Upon maximum levels of amastigote divisions, the macrophages burst releasing more amastigotes that are again re-phagocytosed. When an uninfected sand fly bites an infected individual, the fly ingest the amastigotes and these transform into promastigotes and divide in the midgut of the fly, finally these promastigotes migrate to the proboscis and are now able to transmit the disease. There are no blood stages in the life cycle of L. mexicana.
L. mexicana has the ability to cause both a cutaneous and a diffused cutaneous type of infection. The cutaneous type manifests itself in the form of ulcers at the bite site, here the amastigotes do not spread and the ulcers become visible either a few days or several months after the initial bite, these ulcers heal spontaneously. The diffused cutaneous type manifests itself when the amastigote spreads cutaneously in those with defective Tcell immunity. This type of infection responds very poorly to drugs and therefore causes sores or ulcers all over body.
In 1994, Robertson et al. noted that the amastigotes of L. mexicana have a higher activity of cystein proteases compared to its promastigote forms. This observation is thought to be an important characteristic that may aid in the survival of the amastigote in the macrophages of its host.
Treatment of Leishmaniasis caused by L. mexicana is sometimes unnecessary since the infection tends to disappear spontaneously, but in the cases where the infection becomes prevalent, the treatment of choice is pentavalent antimony, which works in inhibiting the synthesis of ATP. The drug of choice in the United States is Penstostam.
Prevention of L. mexicana infection can be done by avoiding contact with sandfly-infested areas. Although this can be difficult since these flies have been progressively become more adaptive to urban areas. Research is being done to develop a vaccine against the promastigotes, although the work by Roberts may shed light into developing a vaccine or agent that targets the cystein proteases and other enzymes that are found in abundance in the amastigotes.
Leishmania
Leishmania is a genus of Trypanosomatid protozoa, and is the parasite responsible for the disease leishmaniasis. It is spread through sandflies of the genus Phlebotomus in the Old World, and of the genus Lutzomyia in the New World. Their primary hosts are vertebrates; Leishmania commonly infects...
species.
It is associated with leishmaniasis
Leishmaniasis
Leishmaniasis is a disease caused by protozoan parasites that belong to the genus Leishmania and is transmitted by the bite of certain species of sand fly...
.
Leishmania mexicana is an obligate intracellular protozoan parasite that causes a less dangerous form of leishmeniasis. Given its name, this parasitic form occurs in South and Central America. Infection of L. mexicana occurs when an individual is bitten by an infected sand fly that injects the infective promastigotes, which are carried in the proboscis, directly in the skin.
The life cycle of this and other Leishmania species are similar and begin when an infected fly bites and injects it promastigotes in the skin of host and once inside these promastigotes are phagocytosed by macrophages that transform into amastigotes and are able to divide. Upon maximum levels of amastigote divisions, the macrophages burst releasing more amastigotes that are again re-phagocytosed. When an uninfected sand fly bites an infected individual, the fly ingest the amastigotes and these transform into promastigotes and divide in the midgut of the fly, finally these promastigotes migrate to the proboscis and are now able to transmit the disease. There are no blood stages in the life cycle of L. mexicana.
L. mexicana has the ability to cause both a cutaneous and a diffused cutaneous type of infection. The cutaneous type manifests itself in the form of ulcers at the bite site, here the amastigotes do not spread and the ulcers become visible either a few days or several months after the initial bite, these ulcers heal spontaneously. The diffused cutaneous type manifests itself when the amastigote spreads cutaneously in those with defective Tcell immunity. This type of infection responds very poorly to drugs and therefore causes sores or ulcers all over body.
In 1994, Robertson et al. noted that the amastigotes of L. mexicana have a higher activity of cystein proteases compared to its promastigote forms. This observation is thought to be an important characteristic that may aid in the survival of the amastigote in the macrophages of its host.
Treatment of Leishmaniasis caused by L. mexicana is sometimes unnecessary since the infection tends to disappear spontaneously, but in the cases where the infection becomes prevalent, the treatment of choice is pentavalent antimony, which works in inhibiting the synthesis of ATP. The drug of choice in the United States is Penstostam.
Prevention of L. mexicana infection can be done by avoiding contact with sandfly-infested areas. Although this can be difficult since these flies have been progressively become more adaptive to urban areas. Research is being done to develop a vaccine against the promastigotes, although the work by Roberts may shed light into developing a vaccine or agent that targets the cystein proteases and other enzymes that are found in abundance in the amastigotes.