Old world and new world leishmaniasis
A fascinating topic!
Leishmaniasis is a group of diseases caused by protozoan parasites of the genus Leishmania, which are transmitted to humans through the bite of infected sandflies. There are two main forms of leishmaniasis: Old World leishmaniasis and New World leishmaniasis.
Old World Leishmaniasis
Old World leishmaniasis is caused by species of Leishmania that are found in the Mediterranean region, the Middle East, Africa, and Asia. The most common forms of Old World leishmaniasis are:
- Cutaneous leishmaniasis: This is the most common form of leishmaniasis, characterized by skin lesions that can be painful, itchy, and disfiguring. It is caused by Leishmania major, Leishmania tropica, and Leishmania aethiopica.
- Mucocutaneous leishmaniasis: This form of the disease affects the mucous membranes of the mouth, nose, and throat, causing lesions and disfigurement. It is caused by Leishmania braziliensis and Leishmania mazzotti.
- Visceral leishmaniasis: This is the most severe form of leishmaniasis, affecting the internal organs, such as the spleen, liver, and bone marrow. It is caused by Leishmania donovani.
New World Leishmaniasis
New World leishmaniasis is caused by species of Leishmania that are found in the Americas, including the southern United States, Central America, and South America. The most common forms of New World leishmaniasis are:
- Cutaneous leishmaniasis: This is the most common form of leishmaniasis in the Americas, caused by Leishmania mexicana, Leishmania amazonensis, and Leishmania guyanensis.
- Mucocutaneous leishmaniasis: This form of the disease is caused by Leishmania braziliensis and Leishmania panamensis.
- Visceral leishmaniasis: This is a rare form of leishmaniasis in the Americas, caused by Leishmania chagasi.
Key differences between Old World and New World leishmaniasis
- Sandfly species: The sandfly species that transmit leishmaniasis differ between the Old and New Worlds. Old World leishmaniasis is transmitted by Phlebotomus sandflies, while New World leishmaniasis is transmitted by Lutzomyia sandflies.
- Geographic distribution: Old World leishmaniasis is found in the Mediterranean region, the Middle East, Africa, and Asia, while New World leishmaniasis is found in the Americas.
- Clinical manifestations: While both forms of leishmaniasis can cause skin lesions and visceral disease, the clinical manifestations can differ. Old World leishmaniasis tends to cause more severe visceral disease, while New World leishmaniasis tends to cause more severe cutaneous disease.
- Treatment: The treatment of leishmaniasis also differs between the Old and New Worlds. Old World leishmaniasis is often treated with antimonials, while New World leishmaniasis is often treated with amphotericin B.
In summary, while both Old World and New World leishmaniasis are caused by protozoan parasites transmitted by sandflies, there are significant differences in their geographic distribution, clinical manifestations, and treatment.