Mosquito-borne diseases are surging in Europe — how worried are scientists?


Nature News coverage of our work and how climate sensitive pathoges are becoming increasingly common as the insects that spread them move north.

text: Tulio de Oliveira summary photo: James Gathany/CDC via Smith Collection/Gado/ Getty

Researchers warn that climate change is transforming Europe into a breeding ground for mosquito-borne diseases, with elongated summers, higher temperatures, and increased rainfall creating ideal conditions for mosquito populations. This year, the European Centre for Disease Prevention and Control (ECDC) reported 715 locally acquired cases of West Nile virus (WNV) across 15 European countries, exceeding last year’s figures and the 10-year average, with 51 fatalities recorded as of September 2024.

WNV can lead to West Nile fever, characterized by symptoms like fever and fatigue, and severe complications in vulnerable populations, particularly the elderly. The primary vector, the Culex pipiens mosquito, has historically inhabited Europe, but climate change has expanded its transmission capabilities into previously unaffected regions. According to Rachel Lowe, a climate and health scientist, the spread is associated with both climate shifts and increased travel following the COVID-19 pandemic.

Moreover, the Asian tiger mosquito (Aedes albopictus), responsible for transmitting dengue and chikungunya, has established itself in 13 European countries, resulting in reported cases in Italy and France this summer.

As mosquitoes proliferate in line with warmer, wetter conditions, researchers advocate for preventive measures, such as using repellents, wearing suitable clothing, and eliminating standing water to decrease breeding sites. Additionally, there’s growing concern over asymptomatic donors possibly contaminating blood supplies with WNV.

With the rise of these diseases prompting urgent calls for surveillance and preparedness in both endemic and non-endemic areas, experts emphasize the interconnectedness of global health challenges and the need for comprehensive strategies to combat the emerging risks.

Researchers say people who live in areas where outbreaks have been reported should take precautions to avoid mosquito bites.

'We are faced with a problem where new places could become hotspots of transmission that were not prepared for this before,' says Houriiyah Tegally, a genomic epidemiologist at Stellenbosch University in South Africa.

A July preprint from Ethiopian Public Health Institute and Addis Ababa University, KRISP and CERI, on which Tegally is a co-author, found that dengue virus strains in Ethiopia closely resemble those in Italy’s 2023 outbreak. 'It’s impossible to prove the directionality of this movement,' says Tegally. But this 'tells us that the world is very connected, and Europe could at one point, if not already, act as a source of these arboviruses as well, because there’s local transmission'.

Stay Safe: Rising MosquitoBorne Diseases Demand Precautions/p>

As mosquito-borne diseases increase in previously uncommon areas, researchers emphasize the importance of taking protective measures against mosquito bites. It’s recommended to use repellent, wear long-sleeved, light-coloured clothing, and install mosquito screens on windows. Reducing stagnant water in urban environments—such as in gardens, plant pots, and flower vases—can also minimize potential breeding sites. The Asian tiger mosquito, identifiable by its black-andwhite-striped legs, is a key concern.

Scientists warn of the risk posed by asymptomatic carriers who may unknowingly contaminate blood banks with diseases like WNV and Dengue Virus. Although testing mitigates this risk, it could impact the availability of blood and organ supplies; recent data showed that 190 blood donors in the U.S. tested positive for WNV this year.

These emerging risks underscore the necessity for vigilant surveillance of mosquito-borne diseases, even in non-endemic regions.

News piece at Nature:

- https://www.nature.com/articles/d41586-024-03031-y

Preprint:

- Abera, A. et al. Preprint at medRxiv 2024, https://doi. org/10.1101/2024.07.10.24310195


This news piece was published in the gem, Oct/Nov 2024

Click on the image above to read the gem, genomics, epidemics & microbes or scan the qrcode.

News date: 2024-10-31

Links:

https://issuu.com/the.gem/docs/3rdedition_the_gem_newsletter_a4_v2?fr=xKAE9_zU1NQ