HAVANA, Cuba (AFP) – Cuban President Raul Castro announced Monday that 9,200 troops and police have been mobilized in a campaign to eliminate mosquitoes and protect the country against the Zika virus.

Cuba has not officially recorded any cases of the mosquito-borne virus, which is strongly suspected of causing serious birth defects in babies born to infected mothers.

But 28 countries and territories in the Americas and Caribbean have reported cases of active Zika transmission, with 1.5 million in Brazil, the hardest-hit country.

“In this environment, it is essential that all citizens and entities adopt the strictest standards of hygiene and take measures to combat the virus,” Castro was quoted as saying by official media.

The mobilized forces include 9,000 soldiers and reservists, as well as 200 national police.

Countries throughout the region have launched operations to eliminate pools of stagnant water where the mosquitoes, which also spread dengue and chikungunya viruses, can breed.

The World Health Organization has said evidence is growing that Zika causes microcephaly, a birth defect in which a baby has an abnormally small head and often incomplete brain development.

The virus is also believed to be tied to a rise in cases of the paralysis-causing Guillain-Barre syndrome in eight countries, including Brazil, Colombia, El Salvador and Venezuela.

There is currently no cure or vaccine against the Zika virus.

The WHO has warned that the virus’ spread could be “explosive,” infecting up to 4 million people.