Archive for February 23rd, 2010
‘Lame’ mosquitoes to stop dengue
(BBC): Scientists are breeding a genetically altered strain of mosquito in an effort to curb the spread of dengue fever. The dengue virus is spread by the bite of infected female mosquitoes and there is no vaccine or treatment. Experts say the illness affects up to 100 million people a year and threatens over a third of the world’s population. Scientists hope their genetically altered males will mate with females to create female offspring that will inherit a gene limiting wing growth. The study is published in Proceedings of the National Academy of Sciences. The scientists say their approach offers a safe, efficient alternative to harmful insecticides.
Dengue cases not related to MRCU spraying
(CNS): Although the recent suspected cases of dengue fever in the Cayman Islands have yet to be confirmed, government officials say that even if they prove to be positive the appearance of the virus is not related to any reduction in aerial spraying by the MCRU. The mosquito which can carry the dengue fever is present in the Cayman Islands but generally breeds in urban areas and is therefore not controlled by the widespread spraying from the air but by targeted reduction of stagnant water sources in gardens and yards.
MRCU Director Dr William Petrie told CNS that although there are issues currently relating to the unit’s resources and its ability to spray, the Aedes aegypti — the culprit when it comes to passing on the dengue fever virus — does not populate the islands’ swamp areas, where most other mosquitoes set up home and the areas targeted by the aerial spraying.
Dr Petrie said that, as a result, people should be taking extra care to ensure that they turn over pots and empty buckets, wheel barrows, coconut shells or any other vessels that can collect water around their property. He said sceptics who suggest that such efforts can do little to combat the mosquito problem are wrong and that by making sure there is nowhere for this particular mosquito to breed in your garden you will keep them away from your own yard and those around you.
“The Aedes aegypti is not found in swamp areas and tends to breed in urban areas where we do not use aerial spraying. We are encouraging people to keep their yards and gardens as free of standing water as possible as this will keep the population down,’ he said.
Explaining that if the three cases are dengue fever, he said the patients would have contracted the virus from a mosquito or mosquitoes that would have in turn have contracted the virus from another person who was already infected. “The mosquitoes in the Cayman Islands do not carry the dengue fever virus themselves but they can pick it up from another host and pass it on,” Dr Petrie added.
Public health officials have also confirmed that there have been no further cases reported since the three samples were sent for analysis and which are now with the Centre for Disease Control in Puerto Rico. Dr Kiran Kumar confirmed Dr Petrie’s comments regarding the spread of dengue fever and added that it cannot be transmitted via person to person.
Around 100 million cases of dengue fever occur worldwide each year and it is prevalent in the Caribbean as well as Central and South America including Jamaica, Honduras, Trinidad and Tobago, Barbados, Guyana and Puerto Rico. “We do have imported cases from time to time. There has been no evidence of local transmission in the Cayman Islands,” Dr. Kumar said.
With no major outbreaks around the region recently, however, Dr Petrie said it was unusual that these victims had managed to be infected in Cayman as they had no history of travel and without a major outbreak in the region we should not expect to see large numbers of infected people travelling to Cayman unaware of their condition.
He also noted that 2009 had not been a particularly bad year for mosquitoes as the season was not exceptionally wet, but he did admit there was an increase in the overall population around October.
With a constant battle to keep the multiple types of mosquito populations at bay every season, Dr Petrie noted that there were concerns about the MRCU’s stock and the need to keep costs down would impact the battle against the islands’ leading pest, but he said everyone can help by reducing the opportunities for the insect to breed.
Related article: ‘Lame’ mosquitoes to stop dengue