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The fight against COVID-19 should not be allowed to overshadow the risks associated with the dengue epidemics occurring in the French overseas territories

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News of 20/05/2020

In the context of the COVID-19 pandemic, the Directorate General for Health made an urgent request to ANSES to assess the benefit-risk ratio of maintaining the vector control (VC) practices usually implemented against dengue and other endemic diseases spread by mosquitoes. This is because the measures taken against COVID-19 have tended to restrict the actions of professionals and the population, despite the fact that certain parts of the French overseas territories are in an epidemic or pre-epidemic situation with regard to dengue. 

In this context, the Agency points to the need to keep up efforts to control the mosquitoes that carry dengue. It provides guidance on measures to enable those responsible for VC to continue their work, while taking care to limit the spread of the SARS-CoV-2 virus. Lastly, it underlines the need to continue providing ongoing information on the epidemic risks associated with mosquitoes (dengue, zika, malaria, etc.) at a time when general attention is focused on the COVID-19 pandemic.

 

Dengue epidemics: a vector control (VC) strategy undermined during lockdown

To prevent dengue epidemics, integrated vector control strategies (i.e. control of mosquitoes transmitting the pathogens and parasites that cause dengue, chikungunya, malaria, etc.) are implemented every year in the French Overseas départements and regions (Martinique, Guadeloupe, French Guiana, Saint-Barthélemy, Reunion Island, Mayotte, etc.). These have several components:

  • Community mobilisation: door-to-door, communication campaigns in the media, events at markets and neighbourhood meetings, awareness-raising in schools and universities, etc.;
  • Mechanical or physical control, which essentially consists in eliminating mosquito breeding sites (flower vases, gutters, illegal waste dumps, etc., as these promote water stagnation and the establishment of breeding grounds) in public areas and private homes;
  • Chemical control using insecticides and repellents to kill or repel mosquitoes.

The lockdown introduced in all French territories on 17 March to combat the spread of COVID-19 has curtailed or in some cases even put a stop to the implementation of these actions. At the same time, the increase in illegal fly-tipping, due to cleaning operations by households under lockdown, the closure of waste disposal centres in the first few weeks of the lockdown and the disruption to waste collection services, have also contributed to an increase in mosquito breeding grounds.   

 

The Agency stresses the need to continue VC actions even during this COVID-19 period

In this context, and at the height of a dengue epidemic, stopping VC operations could have serious health consequences: an increase in the number of dengue cases, overburdened hospital services, the possible occurrence of dengue-COVID-19 co-infections, a reduction in the reporting of dengue cases and, consequently, in the implementation of VC operations around dengue outbreaks, etc.

Moreover, observation of the epidemiological situation in the French overseas territories between 1 January and 20 April 2020 has revealed that the number of dengue cases is already high (5410 confirmed cases in Reunion Island, 3163 cases and 12 deaths reported in Mayotte, nearly   7680 cases in Guadeloupe, etc.).

Consequently, with the exception of actions requiring gatherings of people and subject to the implementation of conditions minimising the risks of COVID-19 transmission both for VC professionals and for the general population, the Agency recommends resuming the usual VC actions. 

The Agency therefore recommends:

  • guaranteeing that VC services have the material and human resources they need to carry out their tasks on a permanent basis;
  • maintaining surveillance of dengue cases in French territories, as this determines what VC action is needed (around isolated cases, outbreaks, etc.);
  • maintaining active and galvanising communication to the public on the fight against dengue, in a media environment largely commandeered by COVID-19, encouraging the population to:
    • consult a healthcare professional in the event of any symptoms of dengue, while complying with the barrier measures recommended against the spread of COVID-19, o    facilitate the work of VC operators while observing the barrier measures against the spread of COVID-19, 
    • adopt and implement physical control measures: wearing long clothing, eliminating breeding grounds, etc.; 
  • reinforcing the collection of waste and bulky refuse, and ensuring its proper disposal.