Dengue fever ā€“ Republic of the Sudan, 22 November 2019

On 10 October 2019, the Sudan International Health Regulations (IHR) National Focal Point (NFP) notified WHO of 99 suspected cases of dengue fever in Kassala State. The first reported case presented to the health facilities on 8 August 2019 with symptoms including high-grade fever, headache, and joint pain, with or without vomiting.

From 8 August through 4 November 2019, a total of 1,197 suspected cases of dengue fever including five deaths have been reported from seven states: Kassala (1,111 cases; 3 deaths), West Darfur (43 cases; 1 death), North Darfur (29 cases; 1 death), Red Sea (9 cases; 0 deaths), South Darfur (3 cases; 0 deaths), Gadarif (1 case; 0 deaths) and North Kordofan (1 case; 0 deaths).

One hundred twenty-five samples have been tested for Dengue fever, out of which 71 (57%) tested positive at the National Public Health Laboratory in Khartoum, by Immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). Fifty-four percent of cases were female and 93% of cases were above the age of 5 years. Of the 1,197-suspected cases of dengue fever, 95 cases (7.9%) showed hemorrhagic manifestations.

Public health response

The following public health response measures have been implemented:

  • A task force committee has been activated at federal level from 1 August 2019.
  • Surveillance teams have been trained and deployed for daily reporting and active case finding in the affected areas, as of 17 August.
  • Enhanced surveillance and daily reporting have been initiated in 158 sentinel-reporting sites in all localities. Outbreak investigation teams at state and local levels have been reactivated, and all the reported cases have been investigated.
  • Prevention and vector control measures are being applied to the houses of reported cases and surrounding houses.
  • WHO and Sudan Ministry of Health trained 220 health workers in all localities in Kassala State on surveillance, case definition and case management protocols.
  • WHO provided 2,000 ringer lactate drips and 500 doses of paracetamol to fill the gaps in case management supplies.
  • Vector control interventions have been conducted: in Port Sudan, Red Sea State, a total of 1,225 households were inspected, of which 29 were found positive for the presence of Aedes mosquitoes and fogging was done in 1,949 households.
  • WHO supported the printing and distribution of dengue fever case definition and case management protocols in the main hospitals of Kassala State.

WHO risk assessment

Dengue Fever is endemic in Sudan. Several outbreaks have been documented in 2010, 2013 and 2017. Information on the circulating dengue virus serotypes in Sudan is not available. In this regard, more investigation on the dengue virus (DENV) needs to be conducted.

The current dengue fever outbreak is coinciding with other ongoing outbreaks of chikungunya, rift valley fever, malaria, and cholera. Control and response capacities of the public health sector is limited; years of political and civil conflicts have reduced the country capacity to control and prevent outbreaks.

Since the start of the outbreak on 8 August 2019, dengue has spread to seven states across the country. To date, five deaths have been reported. The high likelihood of co-infection with chikungunya and/or malaria complicates case management and may result in poor prognosis.

The risk of international spread of dengue fever virus is high due to the presence of suitable mosquito vectors (Aedes) in the neighboring countries; which are also experiencing floods and seasonal heavy rains, as well as lack of effective vector control programs. Port Sudan, the capital of Red Sea State, is the most important port of the Red Sea with a high volume of international trade and traffic that could potentially lead to further international spread.

WHO advice

The proximity of mosquito breeding sites to human habitations is a significant risk factor for dengue virus infection. There is no specific treatment for dengue infection but early detection and access to proper medical care lowers mortality. Efforts must be made to brief all health workers on the warning signs for severe dengue so that early detection and case management can help reduce deaths. Implementation of effective vector control measures is also critical to dengue prevention and control.

WHO promotes a strategic approach known as Integrated Vector Management (IVM) to control mosquito vectors, including Aedes spp (the primary vector for dengue). IVM activities should be enhanced to remove potential breeding sites, reduce vector density, and minimize individual exposures. This should include both larval and adult vector control strategies (i.e. environmental management, source reduction and chemical control measures), as well as strategies to protect individuals and households. Vector control activities should target all settings where human–vector contact occurs (place of residence, workplaces, schools, and hospitals).

Vector control activities may include covering, emptying, and cleaning of all domestic water storage containers on a weekly basis. In addition, recommended insecticides can be used to outdoor water storage containers. Control measures should also target places of work and schools since Aedes mosquitoes bite during the day.

Where indoor biting occurs, household aerosol products, mosquito coils or other insecticide vaporizers may reduce biting activity. Household fixtures such as windows, door screens and air conditioning units can also reduce biting. Personal protective measures, such as use of clothing that minimizes skin exposure during daylight hours is recommended. Repellents may be applied to exposed skin or to clothing. Insecticide-treated mosquito nets afford good protection against mosquito bites while sleeping, especially for those who sleep during the day (e.g. infants, people confined to beds due to illness or age, dengue patients, and night-shift workers).

Vector surveillance and case tracking should continue to be strengthened within all affected areas and at the national level. Vector surveillance should provide guidance to control efforts and assess impact.

Key public health communication messages on reducing the risk of dengue transmission should continue to be provided through the mass media, health centers, and other public area.

WHO advises against any restrictions of travel or trade to or from Sudan based on the currently available information.

For more information on dengue, please see the following links: