Leishmaniasis and HIV

With the emergence of the acquired immunodeficiency syndrome (AIDS) epidemic in the early 1980s, the diseases caused  by the Leishmania parasites have changed significantly. Particular species that traditionally only caused one type of disease have been shown to be capable of causing other types of diseases. Furthermore, leishmaniasis' classification as a childhood disease has been drastically altered due to HIV-leishmaniasis coinfection. In Spain, where leishmaniasis is a compulsory notifiable disease, it has been estimated that before 1985 approximately two thirds of leishmaniasis cases were with patients less than 15 years of age. However, since then, almost 80 percent of the cases have been in immunodepressed patients, 60 percent of them being HIV positive (Paredes, 1997). There is also a growing consensus that Leishmaniasis be classified as an opportunistic infection and grouped among the other diseases that take advantage of the immunocompromised state of AIDS. Below is a summary of several other problems that are associated with Leismaniasis and HIV coninfection.

Outdated drugs and drug regimens:
 

As explained on the vaccines and treatments page, the current drugs of choice have been on the market since the 1940s, well before the emergence of HIV. Little is known about if and how the drugs for Leishmaniasis crossreact with the drugs for HIV. Furthermore, the drug regimens were designed for use on immunocompetent patients and it is unknown what the dosages should be for immunocompromised individuals (Paredes, 1997).

Emergence of new strains:
Strains of Leishmania that seem to be avirulent in immunocompetent individuals can be capable of causing disease in immunocompromised hosts. These strains react differently to drugs and may transmit themselves in novel ways (Alvar, 1997).

Discovery of new routes of transmission:
 

Case reports exist which suggest that Leishmaniasis can be transmitted through the sharing of injection equipment, sexually, congenitally, and through transfusions. Some of these routes seem to occur more frequently among immunocompromised individuals. This could potentially complicate some attempts to reduce the burden of the disease through means such as vector and reservior elimination (Alvar, 1997).

Synergistic effects of coinfection:
Some research indicates that HIV can reactivate latent Leishmania infections as it attacts the host's immune system. Similarly, Leishmaniasis seems to upregulate many of the cytokines and growth factors that HIV uses for viral replication and regulation. This is alarming as it means that Leishmaniasis/HIV coinfection will lead to quicker immune deterioration by the HIV virus (Wolday, 1998).

Poorer diagnostic ability:
 

Newer serological tests for determining leishmaniasis infection (i.e. ELISA) do not function as well in immunocompromised patients who aren't making antibodies to infections. In these situations, two or more tests must be used making the diagnostic procedure more expensive and less reliable.

Real burden unknown: 

Finally and perhaps most alarming, most of this data comes from southern Europe and Spain in particular where Leishmaniasis is a compulsory notifiable disease. Unfortunately, most of the burden of HIV, Leishmaniasis, and probably coinfection is in Africa, India, and South America where the true impact is not entirely known (WHO, 1996).
from: http://www.who.int/emc/diseases/leish/leisgeo.html

Lee MB, Gilbert HM. Current Approaches to Leishmaniasis. Infect Med 1999;16(1):34,37-45. http://www.medscape.com/SCP/IIM/1999/v16.n01/m3148.lee/pnt-m3148.lee.html

Paredes R, Laguna F, Bonaventura C. Leishmaniasis in HIV-infected persons: a review. Journal. Jun 1997. http://www.iapac.org/clinmgt/coindiseases/leishmaniasis.html

The Special Programme for Research and Training in Tropical Diseases. Leishmaniasis. http://www.who.int/tdr/diseases/leish/default.htm

WHO. Leishmaniasis. Communicable Disease Surveillance and Response. http://www.who.int/emc/diseases/leish/leisgeo.html

WHO. The Leishmaniasis and Leishmaniasis/HIV co-infections. Fact Sheet #116. May 1996. http://www.who.int/inf-fs/en/fact116.html

Wolday D, Akuffo H, Fessahaye G, Valantine A, Britton S. Live and killed human immunodeficiency virus type-1 increases the intracellular growth of Leishmania donovani in monocyte-derived cells. Scand J Infect Dis. 1998;30(1):29-34.