As scientists scramble to get a Zika virus vaccine into human trials by the end of the summer, a team of researchers is working on the first-ever vaccine to prevent another insect-borne disease – Leishmaniasis – from gaining a similar foothold in the Americas.
Leishmaniasis is a parasitic infection passed on through the bite of a sand fly. Using breakthrough CRISPR-cas9 gene editing technology, the researchers – hailing from Japan, Brazil, Canada and the United States – have altered the parasite’s DNA to create a live-attenuated vaccine. If approved, the vaccine will be the first ever to combat a parasite.
“The Ebola and Zika outbreaks show how so-called ‘neglected’ tropical diseases can quickly turn into global public health issues,” says principal investigator Abhay Satoskar, MD, PhD , a microbiologist at The Ohio State University Wexner Medical Center and Center for Microbial Interface Biology. “This vaccine, which has been more than twenty years in the making, could give us the opportunity to stop Leishmania infections before they start, and prevent the type of global spread we’ve seen with other diseases.”
The parasitic protozoa typically causes disfiguring skin infections, but can also silently lurk in the bloodstream, hiding in immune cells and lodging in the spleen, liver and bone marrow with often fatal results. Out of the two million people who are infected each year, 50,000 will die. Current treatments have toxic side effects and are expensive, making effective control of Leishmaniasis in resource-scarce communities difficult. The parasite has also begun to develop resistance against the therapies.
While Leishmaniasis is primarily found in developing nations in Asia, the Middle East and Central and South America, cases have begun to crop up along the southern US border and in Puerto Rico. Thousands of troops from Desert Storm and other Middle Eastern military campaigns have returned with the disease. Sporadic outbreaks in dog kennels across the United States (the parasite is easily transferred between animals and humans) also has public health experts watching closely.
“The sand fly is here. Millions of people travel each year to areas with Leishmaniasis and 90% of those who are infected with the visceral form of the infection don’t have any symptoms,” says co-investigator Hira Nakhasi, PhD, a researcher with the US Food & Drug Administration (FDA)who has been studying Leishmaniasis for decades in order to keep the nation’s blood supply parasite-free. “Diseases don’t recognize borders. Either we can stop Leishmaniasis before it gets here, or we can try to deal with it after. We’re hopeful this vaccine will give us a good head start.”
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