Health Commissioner Darice Plaskett said that a December 2012 investigation into dengue cases in the Virgin Islands confirmed that the territory experienced an outbreak during the peak transmission period associated with increased rains, according to a press release issued Thursday by the V.I. Department of Health.
Plaskett said that the investigation showed that the aedes aegypti mosquito, which transmits the dengue virus, was found in all but one of 10 schools on St. Croix.
“This investigation suggested that schools were part of a larger island-wide dengue outbreak that might not have been identified without school reporting because only a low proportion of suspected cases were reported to the VIDOH,” Center for Disease Control (CDC) epidemiologist Dr. George Han concluded in the study, results of which are available at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6209a1.htm?s_cid=mm6209a1_w.
Health officials requested assistance from the U.S. Centers for Disease Control and Prevention’s Dengue Branch in Puerto Rico after a school nurse and others reported a potential increase in cases among staff and students as well as around the community, according to Plaskett.
Prior to the investigation, DOH Environmental staff conducted surveillance at public, private and parochial schools on St. Croix and in some instances found windows without screen protection or areas with stagnant water where immature stages of mosquitoes (eggs, larvae, pupae) could be produced and put students at risk.
Dr. Han said that six schools were randomly selected in addition to the school where the nurse reported the initial cases. Results of the study showed that of 320 participants, 40 of 202 students or 20 percent, and 20 of 118 staff or 17 percent, were determined to have had dengue in the three months prior to the investigation which was launched in December. Four students tested positive for two of four dengue virus types (DENV-1 and DENV-4), indicating current infection, Han said. The other dengue virus types are DENV-2 and DENV-3.
Han, who led a team of epidemiologists during the investigation, said that they also looked at data retrospectively that dealt with suspected dengue cases at Juan F. Luis Hospital. He noted that 194 patients were tested for suspected dengue in 2012 and of that total, 31 percent was confirmed as positive.
He also noted that while dengue is endemic to this region and the Virgin Islands Department of Health had observed an increase in dengue reporting, reliable baseline case counts were unavailable for comparison.
“USVI residents should undertake practices to reduce mosquito production around dwellings and schools, and visitors should take personal protective measures to avoid mosquito bites,” Han said.
Plaskett said DOH has already taken measures to improve dengue surveillance, reporting and prevention such as:
• improving the physician reporting from to make it more user-friendly;
• using mosquito larvicides to treat containers with water that cannot be eliminated in place of fogging
• routinely inspecting areas like schools that are prone to have containers that accumulate water and produce mosquitoes
• sponsoring training for healthcare providers to improve the care of patients with dengue