Dengue virus serotype 3 has recently re-emerged in several countries and territories in the South Pacific after nearly 20 years. The number of cases is expected to continue to increase in the coming months in many places including Fiji, French Polynesia and Kiribati, while a large outbreak in Solomon Islands is winding down.Currently, health ministries in affected areas are actively building community awareness around how to prevent dengue and refreshing the skills of medical personnel to recognize and treat the symptoms of dengue.
There are 4 serotypes (or strains) of the virus that causes dengue. Infection with one strain will provide life-time protection against that particular strain, but not the other 3 strains. Furthermore, as children are born who have not been infected with a specific dengue virus serotype, they create a susceptible cohort. Therefore, it is not uncommon for dengue serotypes to re-emerge in the Pacific after being absent for 15 to 20 years, likely because the proportion of the population that is susceptible has increased above a certain threshold.
Understanding dengue to prevent transmission
Dengue is a vector-borne disease transmitted by the bite of an infected mosquito. Dengue is not transmitted directly from person-to-person. The mosquitoes that transmit dengue are day-biting Aedes mosquitoes that usually bite during the early morning and late afternoon. They commonly breed in small and medium-sized containers filled with water (including rubbish, plant pots, and water storage containers, etc).
Dengue causes flu-like symptoms that last for 2-7 days, including high fever (40°C/ 104°F) and headaches, pain behind the eyes, nausea, vomiting, swollen glands, joint, bone or muscle pains, and/or rash.
There is no vaccine or any specific medicine to treat dengue. However, anyone with symptoms of dengue should seek medical care, and when warning signs of severe dengue are present (listed above), it is imperative to seek medical care to manage the disease. With early recognition and proper supportive medical care, case-fatality rates are below 1%.
Action to prevent dengue
Enhanced early warning disease surveillance through the Pacific Syndromic Surveillance System (PSSS) – which is a part of the regional Pacific Public Health Surveillance Network – helps early recognition and identification of disease outbreaks, including dengue outbreaks.Ministries in affected countries and territories, such as Fiji, French Polynesia and Kiribati are taking action on three fronts.
- Surveillance: On-going surveillance of dengue is important to track the spread of the disease and to determine whether or not control interventions are working. In the current outbreak, for example, the Ministry of Health and Medical Services in Kiribati has enhanced surveillance for dengue-like illness in all health facilities in the urban area of the capital, South Tarawa and encourages reporting by outer island facilities as well.
- Vector control: The main method to control or prevent the transmission of dengue virus is to reduce the number of vector mosquitoes by preventing them from breeding. In Fiji, the public health prevention activities against dengue, spearheaded by the MOH, involves mobilizing individuals and communities to protect themselves against mosquito bites and to destroy or mitigate mosquito breeding sites. On 16 January 2014, the Fiji Government launched a nationwide anti-dengue clean-up campaign to remove mosquito breeding sites. In Kiribati community-based efforts are focused on promoting environmental clean-up to remove mosquito breeding sites such as discarded boats filled with standing water, tires, discarded drums uncovered water storage and containers and upturned coconut shells.
- Clinical care: Clinicians at all levels of the health system should be aware of a dengue outbreak, be able to identify cases that meet the dengue clinical case definition, and be able to assess which patients have dengue warning signs and require hospitalization and which can be managed safely as ambulatory or outpatient basis. Hospital-based clinicians should also be able to manage more serious cases, including severe dengue cases, according to the WHO dengue clinical management guidelines.
Dengue outbreaks are long lasting within populations; so increased surveillance, vector control and clinical care will be needed for months to come.