First analysis today of tests on mosquitoes

The first results of Guernsey mosquito testing in 2024 start being analysed today, following Public Health concerns after the EU warned that the number of locally-acquired cases of dengue fever doubled last year.

Director of public health Dr Nicola Brink said the recent detection of Asian tiger mosquitoes in several European countries was a cause for public health concern. (Picture by Sophie Rabey, 33335240)

The Asian tiger mosquitoes, which carry the illness, are now established across the majority of France, as well as Italy, the Balkans and southern Spain.

The first recent EU dengue outbreak was in 2010, but there have been 48 since then.

Of these, seven were in 2020 and 10 in 2022. Last year it peaked with eight outbreaks in France, four in Italy and two in Spain.

This resulted in 130 locally-acquired cases of dengue reported in the EEA/EU last year, compared with 71 cases in 2022.

Imported cases are also on the rise, with 1,572 reported cases in 2022 and more than 4,900 cases in 2023.

Director of public health Dr Nicola Brink said the recent detection of Asian tiger mosquitoes in several European countries was a cause for public health concern.

‘These mosquitoes are competent vectors for a number of debilitating viruses, such as dengue fever, chikungunya fever, and Zika,’ she said.

‘Climate change is playing a significant role in their spread, as rising temperatures allow them to establish themselves in areas previously unsuitable due to cold winters.

‘Increased global travel also presents a risk, as travellers can inadvertently transport mosquito eggs or adults across borders.’

The mosquito species Aedes albopictus, a known vector of chikungunya and dengue viruses, is establishing itself further northwards and westwards in Europe, according to the latest data from ECDC. Also, Aedes aegypti, known to transmit dengue, yellow fever, chikungunya, zika and West Nile viruses, has been established in Cyprus since 2022 and may continue to spread to other European countries. (Image copyright of ECDC. )

No Asian tiger mosquitoes were identified in Guernsey last year.

Two weeks ago Environmental Health officers set the first ovitraps in four locations – at the two commercial sea ports, the airport and at a local freight company. These will be checked bi-weekly, and the first samples will be submitted for analysis today.

The traps will be inspected for any mosquito eggs under a microscope and analysed.

Any suspicious finds will be photographed and sent to the UK Health Security Agency for their opinion. Molecular techniques are also being used locally to confirm if the eggs are Asian tiger mosquitoes, as well as the option to use DNA sequencing.

The data will be used to demonstrate whether Asian tiger mosquitoes have been identified in Guernsey, to consider the extent of the risk posed and to inform suitable public health interventions.

Among the outbreaks in France last year was one in Paris – the most northerly outbreak recorded, about 200 miles east of St Malo. It saw three members of the same family become ill. None had travelled, but all recovered. It has led to concerns about the upcoming Olympics.

Dengue is mainly native to Africa, Asia and central and South America.

Not all dengue has symptoms, but can develop within four to 10 days and include fever, headache and joint pain.

Some people develop severe dengue and in rare cases, it can be fatal.

As well as increase in dengue, there are also worries about the rise in West Nile virus, also carried by the EU-native common house mosquito.