Costa Rica’s Ministry of Health is planning to use bacteria in the fight against the Aedes aegypti mosquito, which spreads Zika virus, dengue, and chikungunya, amongst other viruses and diseases.

 

The bacterium, known as Saccharopolyspora spinosa, is the only bacterium known to secrete spinosad, a natural pesticide consisting of spinosyn A and spinosyn D and which kills mosquito larvae in 48 hours, according to Costa Rican health officials.

 

According to the National Insitutes of Health (NIH) in the United States, the bacterium has no toxic effect on humans.

 

The bacterium is applied in tablet form to standing water where mosquitos are believed to be reproducing. The tablets can also be used in potable water tanks and storage facilities.

 

While the bacterium is effective in destroying mosquito larvae, it is not effective on adult mosquitoes, according to Costa Rica health officials.

 

In a statement, Costa Rica’s Ministry of Health described the bacterium as “the best choice in biological technology to control [mosquito] larvae available in the market,” adding that a single application can control breeding for 10 weeks, even with water circulation rates of up to 80 percent.

 

The bacterium is expected to be deployed in areas such as drainage ditches, streams, ponds, fountains, potable water storage areas, and other places where the mosquitos reproduce. The bacterium is also expected to be deployed at hotels, schools, industrial sites, and other large facilities.

 

Still, health officials are advising the public that the best prevention is the complete elimination of mosquito breeding sites, and are urging homeowners and businesses to eliminate any areas of standing water on their properties.

 

The Zika threat

 

Zika is a mosquito-borne virus that is sweeping through South and Central America. Its initial symptoms are mild. The main ones, according to the U.S. Centers for Disease Control and Prevention, are “fever, rash, joint pain and conjunctivitis” or red eyes. Severe cases can linger for up to a month and sometime send patients to the hospital.

 

The real threat, according to the CDC, seems to be a link between Zika and a serious birth defect called microcephaly, in which babies’ heads and brains are unusually small “compared to babies of the same sex and age.” The defect has shown up in the babies of women infected with Zika during pregnancy.

 

There is no vaccine or medical treatment currently available for Zika, and the World Health Organization (WHO) recently warned that as many as four million people could become infected as the virus spreads rapidly through the Americas.

 

Up to 60,000 cases possible in Costa Rica

 

Medical epidemiologist and newly-appointed coordinator of Costa Rica’s National Disease Vector Control Program, Rodrigo Marin Rodriguez said that Costa Rica could see up to 60,000 cases of Zika infection in a worst case scenario in an interview published by the daily La Nacion on Friday.

 

Marin was appointed to the post last Tuesday, the same day that health officials announced the first imported case of Zika in the country.

 

Marin bases his “worst case” scenario on estimates from Colombia, which currently has an indigenous outbreak of Zika and where conditions are very similar to Costa Rica.

 

According to Marin, officials there expect 600,000 cases of Zika and 500 cases of microcephaly, a birth defect which causes babies to be born with unusually small heads and brains and which is linked to the virus, in a country of 50 million inhabitants.  Given the similarities between the two countries, Marin thus estimates that Costa Rica could see some 60,000 Zika cases amongst the country’s 5 million inhabitants.