Dengue Epidemic in Sao Tome and Pricipe

Dengue is a mosquito-transmitted virus. Dengue is present in tropical and subtropical climes worldwide, particularly in cities. Aedes aegypti and Ae. albopictus mosquitoes spread the illness. Dengue virus causes dengue (DENV). Four DENV serotypes may cause infection four times. Over 80% of DENV patients have no symptoms (asymptomatic). DENV causes flu-like symptoms. Severe dengue is a potentially dangerous consequence.

There is no particular therapy for dengue, but early diagnosis, detection of warning symptoms of severe dengue, and good case management are crucial to preventing patient fatalities. Dengue fatalities are frequently due to delayed medical intervention.

Occasional cases acquired abroad have been documented among people returning from a dengue-transmitting location, but there is no solid proof that So Tomé and Prncipe have imported dengue. So Tomé and Prncipe have never recorded a dengue epidemic despite being in the dengue belt and having favorable circumstances to transmit dengue.

Healthcare response

The epidemic has prompted the following actions by national health authorities:

• Holding weekly meetings between MoH and WHO to discuss outbreak technical aspects • Developing, validating, and disseminating a dengue response plan 

• Conducting multidisciplinary epidemiological investigations and active case detections in several health districts 

• Conducting entomological investigations to identify breeding sites and fogging and source reduction measures in some affected localities

• Sharing a daily illness bulletin with WHO

• Organizing deployments of foreign specialists to increase laboratory capacity in So Tomé and Prncipe, as well as case management, risk communication, entomology, and vector control

WHO evaluation

The risk at the national level is high due to the presence of the mosquito vectors Aedes aegypti and Aedes albopictus; (ii) favorable environment for mosquito breeding grounds following heavy rains and floods since December 2021; (iii) concurrent outbreaks of diarrheal disease, malaria, COVID-19, and other health challenges; and (iv) decreased functionality of sanitation and water management systems in health facilities due to structural damage. A substantial majority of dengue patients are asymptomatic, and monitoring and diagnosis are limited. Management of severe dengue is very difficult. Community awareness is limited and risk communication is lacking.

Regional and global risks are minimal. Therefore Tomé and Prncipe is an islands with no land boundaries, so future expansion would need vectors.

WHO tip/Detection

• It's crucial for health facilities to have dengue diagnostic testing.

• Health facilities on So Tomé and Principe's outlying islands should be informed about the epidemic and given RDTs to identify cases.

• Integrated Vector Management (IVM) should be upgraded to eliminate breeding places, decrease vector populations, and limit individual exposure. This includes larval and adult vector control, such as environmental management, source reduction, and chemical control.

• Vector control measures should be adopted in homes, workplaces, schools, and hospitals to avoid vector-person interaction.

• Source reduction and vector monitoring should be begun.

• Wear clothing that reduces skin exposure and apply repellents to exposed skin and garments. Use repellents according to the label.

• Window and door screens and insecticide-impregnated mosquito nets may limit vector-person interaction in confined environments.

• Current WHO information does not propose any travel or trade restrictions to So Tomé and Prncipe.