No new confirmed cases of dengue fever have been reported since 18 January.
Since the first reported case of dengue in this outbreak occurred last September, 127 cases have been investigated – 94 between September and December 2012 and 33 so far this year.
The Cayman Islands Public Health Department received the lab results of four suspected cases last week from the Caribbean Public Health Agency, previously known as the Caribbean Epidemiology Centre, or CAREC. All four tested negative for dengue.
Since the last update from the Public Health Department, as of February 2, two new cases came under investigation between 3 and 9 February. One was admitted to the hospital. Neither patient – one from West Bay and one from George Town – had a travel history to an area where dengue fever is endemic.
Of the cases investigated for dengue, 40 have been positive, 65 were negative and four were inconclusive. The results of 18 of the cases are still pending.
Of the 40 confirmed cases, 12 had a travel history to endemic countries and 28 had no travel history, suggesting that they acquired the virus locally.
Four of the confirmed cases have been in Bodden Town and five in George Town. Most of the cases have involved residents of West Bay, with 31 people from there contracting the virus.
Of the 28 who acquired dengue after being bitten by an Aedes aegypti mosquito in the Cayman Islands, which is a vector of the virus, 24 are from West Bay, two from George Town and two from Bodden Town.
So far, 30 people have been admitted to the hospital for suspected dengue, including one last week. Aerial spraying for the dengue carrying mosquito had eased off earlier this month, as it appeared the number of newly confirmed cases were decreasing.
However, as of 2 February, four more cases were confirmed to be positive for the virus, prompting the Mosquito Research and Control Unit plane to take to the air again.
“During the outbreak, MRCU carried out early evening aerial and ground control operations within the known areas of dengue transmission. Work crews were also assigned to survey and treat all yards within the area and in other areas where suspected cases had occurred. Given that the last confirmed case of locally transmitted dengue occurred before 10 December, 2012, aerial control operations have now ceased,” said Alan Wheeler, assistant director of the MRCU, in a press statement released Monday, 11 February. That release was written before the 2 February update on dengue was published.
Mr. Wheeler said the decision to stop the plane from spraying sites had nothing to do with budget constraints, but instead “the rationale behind it is that MRCU does not wish to apply chemical without a demonstrated need to do so, in order to prevent the possibility of the mosquito becoming resistant to the chemicals we use”.
According to Dr. Wheeler, the control unit has sufficient chemicals and equipment to respond to any mosquito issues as and when they arise. “At the moment, the mosquito population is at low levels and, therefore, the intensity of both aerial and ground-based control operations has decreased,” he said.
He added that the spraying process continues around Grand Cayman, especially in the “trouble spots”.
The control unit responds with spraying teams to locations where a case of dengue is suspected.
Premier Juliana O’Connor-Connolly put out a renewed call to the public last week to help fight the spread of dengue fever in the Cayman Islands.
“Please ensure there is no standing water on your property for the Aedes Aegypti mosquito to breed. This mosquito is the dengue vector and it loves to breed in old tyres and containers in which water settle. So, please properly dispose of any old tyres and containers in which water may settle,” Ms O’Connor-Connolly said.
Mr. Wheeler said the outbreak had resulted from multiple introductions from other countries over a very short period of time.
“When [a] dengue-infected person enters the island, it may take several days for them to become ill and visit a doctor. During this time, they may be transmitting dengue locally before they, the hospital or MRCU are aware that there is a problem. In addition to the delay due to the incubation period of the disease, there is also a delay in confirming that a patient actually has dengue. This may take several weeks.”