How can the dengue outbreak in Cuba affect us?

Dengue was identified by the World Health Organisation (WHO) in 2019 as one of the 10 diseases with the greatest potential to threaten global public health. The main reason: the tendency of this viral disease to increase its incidence throughout the world in recent decades, and to expand in areas where it did not previously exist, due to an increase in mosquito populations, a more favourable climate, and the lack of interventions to combat it in many cases.

Despite being considered by many people in Europe as a distant and exotic disease, each year there are about 100-400 million people infected with this virus in countries with warm or temperate climates. This year, there is a major outbreak of dengue in Cuba and this summer a considerable number of Catalans returned from their holidays with the disease: more than half of the cases of dengue we have diagnosed in Catalonia came from Cuba.

Dengue patients usually have fever, headache, severe muscle and joint pain (the disease is also called breakbone fever) and a characteristic skin rash in about half of viral fever cases. The acute phase can last 5 or 6 days and some patients may have severe dengue, especially vulnerable people who have had dengue before.

Since the dengue virus can be transmitted by Aedes albopictus, the Asian tiger mosquito (which also transmits zika, chikungunya and yellow fever) present throughout the Mediterranean, Barcelona has an epidemiological control programme that consists of reporting cases and reducing mosquito populations, especially around imported cases of dengue. In fact, the Mediterranean area was endemic for dengue until around 1927 (when the disease was transmitted by Aedes aegypti, another mosquito species from the Aedes genus). Since then, we were free of the disease (except for international travellers) until a few years ago. In the last decade, we have once again had autochthonous cases of dengue (transmitted by local mosquitoes) in Italy, France, Portugal (Madeira) and Croatia. And in 2018 and 2019, there were 7 cases diagnosed in Spain (2 in Catalonia and 5 in southern Spain).

This year, 2022, after a few years with little international travel, Europeans have begun to travel again. Now imported dengue patients are being diagnosed again in our hospitals and primary care centres, and we are again at risk from the disease entering our territory. So far in 2022, France has diagnosed more than 20 autochthonous cases that started the cycle of infection through local Asian tiger mosquitoes.

In Catalonia, no case has yet been reported. This difference in the incidence of reported cases may be due to the fact that we have not had them or because they have not been detected. But the reality is that Catalonia is a region at high risk of the introduction of these mosquito-borne diseases (mainly dengue, chikungunya and zika) and, therefore, it is vital to be prepared and have response mechanisms that are fit for purpose. Just recently, the Local Government of Catalonia reported two possible cases of West Nile virus in residents from the Camp de Tarragona health region. This is another mosquito-borne disease we need to keep a close eye on.

The COVID-19 epidemic taught us (I hope) that the direction and intensity of emerging diseases are difficult to predict. Therefore, it is vital to increase efforts in the mechanisms to anticipate and detect these diseases early, in addition to promoting research and innovation studies so we are ready to respond to this and to any other emerging disease in the future.

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