Mosquito unit steps up dengue fight

The Mosquito Research and Control Unit is stepping up its fight to keep the Cayman Islands free of dengue fever this summer.

Four new survey officers and two new vehicles will be enlisted to help reduce the population of the Aedes aegypti mosquito, a potential dengue fever carrier that lives in residential areas.

The survey officers will be doing what MRCU Director William Petrie likes to call ‘boots on the ground work’ – going from house to house inspecting properties, spraying for adult mosquitoes, collecting samples of the species and treating potential breeding areas to kill larvae.

‘It only breeds around human habitation; mainly in people’s yards,’ explained Mr. Petrie. ‘Therefore, our aircraft and fogging truck control operations (which targets swamp, mangrove and pasture areas) don’t really have much effect.

‘It’s a labour intensive operation; it’s boots on the ground work, in that you need to get around people’s yards and premises.’

The MRCU is intensifying its fight against the mosquito after 2007 saw large scale dengue fever outbreaks across much of the Caribbean and Central America. Experts expect the trend will continue through the region this summer.

While dengue fever is not endemic to the Cayman Islands, the presence of Aedes aegypti – whose population increased by 1,300 per cent on Grand Cayman following Hurricane Ivan – leaves open the possibility that the mosquito could bite an infected person and then spread the disease locally. There are no Aedes mosquitoes on the Sister Islands.

Mr. Petrie said: ‘We are trying to be pre-emptive; we are erring on the side of caution.’ The aim is to reduce the population here so that if there is a dengue outbreak in the region, there is less chance of a local Aedes mosquito coming into contact with an infected person, he added.

Mr. Petrie urged residents to look after themselves and their families by clearing all standing water around their houses and workplaces.

Between October 2007 and February 2008, the Cayman Islands saw 13 cases of dengue fever, including one death. In each case, Public Health officials said the patients had imported the disease, having travelled to countries where dengue fever is endemic in the weeks before reporting symptoms. There was no evidence of the disease being spread locally.

Howard Anthony Morrison, who died in early January from the disease, had become ill shortly after returning from a trip to Jamaica, but delayed seeking medical attention for five days. The 38-year-old eventually presented to the Cayman Islands Hospital in a critical condition and went into cardiac arrest within minutes of arriving there.

Experts have pointed to changing weather patterns as one of the reasons for the recent spike in dengue cases in the region, but Mr. Petrie said increased labour movement is also an important factor.

‘It’s not just climate change in isolation, it’s the movement of labour – the globalisation of the economy – that moves diseases around,’ he explained.

‘You have labour moving more than ever before,’ he continued. ‘People typically think it is the mosquitoes that move the diseases around the world. They do in a local sense but it’s the movement of labour that moves the disease from country to country.’

Director of Public Health Dr. Kiran Kumar pointed out there is no vaccine for dengue fever and asked people to take protective measure when travelling to countries where the disease is prevalent, including wearing long sleeved clothing and using mosquito repellent.

Those travelling to places where malaria is present should seek advice about whether anti-malarial tablets are appropriate, he said.

Those travelling overseas who are unsure about what precautions to take can book an appointment with the Public Health Department’s International Travel Clinic for country specific advice, he said. Their number is 244-2648.


‘It’s not just climate change in isolation, it’s the movement of labour – the globalisation of the economy – that moves diseases around.’

– MRCU Director William Petrie

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