THE Ministry of Health (MOH) is urging Jamaicans to keep the doors to their houses open during fogging activities as the aedes aegypti mosquito, which is responsible for the spread of the Zika virus, rests mainly indoors.

As a result, Permanent Secretary in the Ministry of Health, Dr Kevin Harvey said fogging, at its best, will only wipe out up to about half of the adult mosquito population.

“These mosquitoes rest mainly inside of your house, so as you can imagine fogging around the house and the community only get to a certain percentage,” he said, while addressing a Jamaica House press briefing on Wednesday.

Concerning a long-held view that the insect has become immune to the chemicals used in the fogging, Dr Harvey disclosed that there is some resistance to one of the chemicals, which has since been replaced.

Meanwhile, Sherine Huntley Jones — medical entomologist in the MOH — said that the resistance comes with the fact that the mosquitoes stay indoors.

“As it relates to the chemicals we use in our vector control programmes, all the chemicals are effective. As the permanent secretary said, we have detected resistance to one of our chemicals and the ministry has replaced that chemical and will be using the effective chemicals in the areas where resistance has been detected,” she said, adding that the chemical the mosquito was resistant to was the malathion, which has been replaced by the anvil and deltamethrin — commonly used to combat the deadly West Nile virus and malaria respectively.

She said it is necessary to leave windows and doors open to allow the fog to drift inside.

“Because this mosquito is on the inside, if the fog is not getting on the inside, we will not be able to get to the population. The chemicals are effective but the process of fogging may have drawbacks because the mosquitoes are on the inside and persons do not necessarily all the time open their windows and doors,” she explained.

The medical entomologist also assured that the chemicals were safe, but said people with respiratory illnesses must cover their nose with a wet rag or leave the area at the time of fogging as each community is notified before fogging occurs.

On Wednesday the health minister, Horace Dalley, urged caution against the imminent outbreak of the virus, which has so far been detected in several countries in the region, including Barbados, Bolivia, Brazil, Colombia, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, St Martin, Suriname and Venezuela.

The US state of Florida also confirmed three ZikV cases, two of them in the Miami-Dade county.

Meanwhile yesterday, Suriname’s Public Health Bureau said that a 75-year-old man had become that country’s fourth casualty of the mosquito-borne virus.

The bureau said the man died on the weekend at the Academic Hospital, and had also shown symptoms of other health problems.

— Kimberley Hibbert