Research in the field, lab and clinic by Brazilian scientist Dr. Edgar M. Carvalho is yielding a better understanding of leishmaniasis, a parasitic disease spread by the bite of sandflies. Carvalho will describe his research on the interplay between leishmania parasites and their human hosts at the 2008 Gorgas Memorial Leon Jacobs Lecture, scheduled for Friday, May 30, at 2 p.m. in Wilson Hall, Bldg. 1.

Cutaneous leishmaniasis is sometimes called “year-long sore” because the condition’s characteristic skin ulcers can take that long to heal. Most of the 1.5 million annual cases occur in six countries: Iran, Afghanistan, Syria, Saudi Arabia, Peru and Brazil. Brazil is one of four countries in which the vast majority of cases of visceral leishmaniasis, the most lethal form of the illness, occur. Brazil, too, is the site of many cases of mucosal leishmaniasis, which can result in massive tissue destruction in the nose, mouth and throat.

Most people infected by any of the 20 different species of leishmania parasite mount an effective immune response and gradually rid themselves of the parasite. But about one-quarter of infected people, notes Carvalho, develop cutaneous or mucosal leishmaniasis, despite having immune responses that appear superficially similar to those seen in people who do not develop disease. Carvalho hypothesizes that the host immune response itself—in the form of exaggerated and unregulated inflammation— plays a key role in determining why some infected people develop disease and others do not.

Treating leishmaniasis, especially its mucosal form, is not easy, says Carvalho. Building on the evidence that an excessive immune response spurs the development of mucosal leishmaniasis, he and colleagues conducted a clinical trial in which some trial participants received at least one course of antimony, the standard treatment for the disease, while others received antimony along with a compound called pentoxyfilline, which inhibits an immune molecule that promotes inflammation. The participants who received the pentoxyfilline needed only one course of standard drug treatment and their infections required significantly less time to heal than those in people who received the standard treatment alone.

In addition to studying leishmaniasis, Carvalho has also collaborated with NIAID’s Dr. Franklin Neva in defining immunological and clinical features of people co-infected with human T-cell lymphotropic virus-1 (HTLV-1) and the parasitic roundworm Strongyloides stercoralis. In 2001, Carvalho helped establish an HTLV-1 clinic at the Federal University of Bahia (UFBA) University Hospital. Since then, about 700 HTLV-1-infected individuals have been examined, allowing for characterization of clinical manifestation of the viral infection as well as a better understanding of human and viral factors associated with disease development.

Carvalho is professor of medicine at UFBA and professor of clinical immunology at Bahiana Medical School in Salvador, Brazil. He has been an adjunct professor at Weill Medical College of Cornell University since 1998 and at the University of Iowa since 2007. He received his M.D. and Ph.D. from UFBA Medical School. In recognition of his contributions to the understanding of infectious diseases, Carvalho received Brazil’s Sendas Award in 1993. The author of more than 230 scientific publications in tropical medicine, he was elected to the Brazilian Academy of Science in 2002. In 2005, Brazil’s President Luis Inacio Lula da Silva admitted Carvalho to the Brazilian Class of Scientific Merit.