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Flesh-eating bacteriaFlesh-eating parasites come closer, but a vaccine against them does, too

Published 25 September 2017

Parasites that ulcerate the skin, can disfigure the face, and can fatally mutilate internal organs are creeping closer to the southern edges of the United States. No vaccine is yet available against Leishmania — the second-deadliest parasites in the world, topped only by malaria — but researchers have now come closer to changing that. A new experimental vaccine has immunized laboratory mice that were genetically altered to mimic the human immune system. The vaccine exploits a weakness in Leishmania’s tricky chemical camouflage, which normally hides it from the victim’s disease-fighting cells, to trigger a forceful immune response against the parasite.

Parasites that ulcerate the skin, can disfigure the face, and can fatally mutilate internal organs are creeping closer to the southern edges of the United States.

No vaccine is available against Leishmania yet, but researchers have now come closer to changing that. A new experimental vaccine, made with a proprietary biological particle developed at the Georgia Institute of Technology, has immunized laboratory mice that were genetically altered to mimic the human immune system.

The vaccine exploits a weakness in Leishmania’s tricky chemical camouflage, which normally hides it from the victim’s disease-fighting cells, to trigger a forceful immune response against the parasite, according to a new study.

Second-deadliest parasite
Georgia Tech says that Leishmaniaare the second-deadliest parasites in the world, topped only by malaria, according to the World Health Organization. There are some thirty strains of Leishmania.

They are transmitted mainly through the bite of a phlebotomine sand fly, which feeds on blood, and global warming is expanding the insect’s potential habitat northward from Latin America. The outbreak regions closest to the United States of leishmaniasis, the disease caused by the parasite, have come within roughly 300 miles of the border.

As with many diseases, many people who contract Leishmania, the parasite, may develop leishmaniasis, the disease, with varying symptoms, or perhaps even show no outward signs of the disease. But when it breaks out, it can cause large skin boils, and some forms severely eat away at the nose and lips, even removing parts of them.

If another form of the parasite gets into the bloodstream, it can damage the liver and spleen in a deadly form of the disease called visceral leishmaniasis, also known as black fever.

“If you don’t treat it, within 20 to 40 days visceral leishmaniasis very often kills the victim,” said Alexandre Marques, a professor in the parasitology department of the Universidade Federal de Minas Gerais in Brazil, and one of the lead researchers on the new experimental vaccine. Conventional treatment, though mostly effective, can leave behind small numbers of the parasite, which can lead the patient to relapse or act as a carrier, in a similar manner as malaria.

A vaccine could be better at halting or averting outbreaks.