Sambo fish are the newest warriors in the battle against the Zika virus. Sambo love to feast on mosquito larvae, a proclivity scientists hope to use to control the population of Aedes aegypti, the mosquito that transmits not only Zika but dengue and chikungunya.

Operation Blessing International, a Christian humanitarian organization, is placing the fish in stagnant water containers in homes, schools, and restaurants in El Salvador. Since residents there often have to travel long distances for safe water sources, they store water in open barrels and catch rainfall in storage tanks, creating a perfect breeding ground for the mosquitoes, which lay their eggs in the stagnant water. The eggs then morph into larvae. Operation Blessing hopes the small sambo fish will consume enough larvae to control the mosquito population and reduce the transmission of Zika.

Sambo, also known as zambo, are indigenous to El Salvador, so the project is not introducing a new species to the area, an organization spokesman said in a video. And the group is not placing the fish in natural waterways where they might impact the environmental balance.

Operation Blessing successfully used sambo in a trial run in the El Salvador village of San Diego between 2012 and 2015. During that time not one case of dengue, chikungunya, or Zika was reported in the area, Marielos Sosa, a health worker, told the website Tech Times.

Operation Blessing is now working to develop more efficient sambo breeding methods. “We’re going to need hundreds of thousands of these fish in order to tackle this throughout the country,” the spokesman said.

Hot beans

Good news and bad news from a World Health Organization study of coffee and cancer: The good news is researchers did not find conclusive evidence that coffee itself is carcinogenic. The bad news is they found drinking very hot beverages—above 158 degrees Fahrenheit—may cause cancer of the esophagus due to inflammation. The hotter the beverage, the higher the risk. The researchers published their findings in The Lancet Oncology in June. —J.B.

Thickening solution

Spark Therapeutics, a Philadelphia company, announced promising results last month in preliminary tests of a new gene therapy to treat a dangerous blood disorder known as hemophilia. People with hemophilia lack a blood factor necessary for clotting: They bleed easily and excessively, and even a minor injury can be fatal. Standard treatment involves regular intravenous infusions of the missing clotting factor.

To develop the new therapy, researchers engineered viruses to carry the gene that instructs the liver to make the needed clotting factor. Then they infused the virus into four hemophilia B patients. In all four cases, factor activity increased to about 30 percent of average—still not normal, but a significant improvement.

Spark needs to perform a much larger study to show the results are reproducible. And one hurdle remains: The treatment would not help about 40 percent of hemophiliacs, Lindsey George, a doctor who participated in the study, told MIT Technology Review. The type of virus the researchers used is similar to one that commonly infects people. People previously infected with the virus carry antibodies in their blood that would destroy the engineered virus before it got to the liver. The company is looking into a method to release decoy viruses to soak up the antibodies first. —J.B.