Leishmania Equatorensis

In this study, Grimaldi et. al. (1992) describes a new species of Leishmania, Leishmania equatorensis, that was discovered within the liver and spleen of both a sloth and squirrel that were captured in Naranjal, Ecuador in 1982.  In humans, Leishmania is responsible for causing the disease Leishmaniasis, which has three forms.  There is visceral leishmaniasis, which infects mostly the liver and spleen, cutaneous leishmaniasis, which infects the skin, and muco-cutaneous leishmaniasis, which infects the mucous membranes.  All three forms are caused by a different species in the genus Leishmania.  The new species described in this paper was determined to be most closely related to Leishmania braziliensis, which is responsible for muco-cutaneous leishmaniasis, also known as espundia.  L. equatorensis was determined to have the same behavior as L. braziliensis, in terms of its virulence (its ability to cause disease) and the way it develops inside of lab animals.  The hamsters that were exposed to  L. equatorensis developed swelling and eventually lesions on the nose, in anywhere from one to three months time.  This is identical to how L. braziliensis acted.  L. equatorensis was determined to be a new species by the differences in the molecular make-up compared to other species of Leishmania. 

            The original description of this parasite does not answer many questions about the parasite itself.  Two of the big questions raised from the original description are, first, is it dangerous to humans, and second, what is the sand fly vector for this parasite?  Being a new species of the L. braziliensis complex (a species complex being organisms that can’t reproduce with each other but are almost identical in every other way) means that L. equatorensis may be dangerous to humans.  L. braziliensis causes espundia, which can lead to lesions that cause deformities around the nose and mouth.  It can also be fatal if the disease spreads to the larynx and trachea where it may cause septic bronchopneumonia (Garnham, 1971).  Being so closely related, it’s possible that L. equatorensis may cause the same symptoms and complications, and may also be deadly.  If it is harmful to humans, it’s good that it was discovered in these reservoir hosts, and no humans have been infected yet.  This gives researcher’s time to get a better understanding of the organism to hopefully prevent the transmission to human’s altogether.  Because this species is so closely related to L. braziliensis this may be a good reason to look for a decent cure for espundia.  Currently antimony is used to try and kill the parasite but this is also very toxic to humans (Hepburn, 2000).  If more species are being found that could potentially be dangerous to humans, a better treatment may want to be sought out.      

http://www.scielo.br/pdf/mioc/v87n2/vol87(f2)_052-059.pdf

Garnham, P.C.C.  1971.  American Leishmaniasis.  Bull. Wld. Hlth. Org.  44:  521-527. 

Grimaldi, G., Jr., R.D. Kreutzer, Y. Hashiguchi, E.A. Gomez, T. Mimory, and R.B. Tesh.  1992.  Description of Leishmania equatorensis SP. N. (Kinetoplasida: Trypanosomatidae), a new parasite infecting arboreal mammals in Ecuador.  Mem. Inst. Oswaldo Cruz.  87: 221-228.

Hepburn, N.C.  2000.  Cutaneous Leishmaniasis.  Clinical and Experimental Dermatology.  25: 363-370.