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Updated on 06/01/2021

Learn all about vectors and the issues associated with their control

Keywords : Vecteurs, Vector control (VC), Ticks, Mosquitos

Lyme disease, Zika, chikungunya, dengue... Recent years have seen a re-emergence of the pathogens responsible for these diseases, which are transmitted by insects and other arthropods. On Thursday 17 December 2020, ANSES is hosting a scientific webinar on the new prospects for controlling these species, known as vectors. The Agency is taking this opportunity to explain exactly what these pathogen vectors are: not only tiger mosquitoes and ticks, but other vectors of diseases specifically affecting animals or plants. What is ANSES doing in the areas of expert appraisal and research to address these health issues? All the answers are in this dossier on the subject.

  1. What is a vector and what are ANSES's tasks in this area?
     
  2. Mosquitoes and ticks : focus on the main vectors of disease in humans
     
  3. Vector-borne diseases in animals or plants
     
  4. Control strategies and reseach on innovation

 


1 ➡ What is a vector and what are ANSES's tasks in this area?


A vector is an arthropod – a member of a group including insects and arachnids – that transmits a pathogen (a virus, bacterium or parasite). It acquires this pathogen by feeding on an infected host, and then transmits it to other individuals.

According to the World Health Organization (WHO), vector-borne diseases account for more than 17% of infectious diseases worldwide and cause more than one million deaths each year.

Climate change, international trade and transport, urbanisation and agricultural practices are all factors promoting the spread of vectors beyond their natural range. The challenge when combating vector-borne diseases is to be able to implement integrated strategies, ranging from control of vector species to prevention of bites, using not only chemical solutions, but also mechanical or biological methods to avoid the use of chemicals that may cause resistance.

ANSES has been providing scientific expertise on vectors and their control since 2018. It aims to support the public authorities in order to better prevent and control the risks associated with vector transmission of pathogens. Among other things, this involves scientific monitoring.

Johanna Fite, Project Officer for Vectors, provides some explanations

Find out more about vectors and ANSES's tasks in this area.

 

 


2 ➡Mosquitoes and ticks: focus on the main vectors of disease in humans

While mosquitoes are the primary vectors of disease in the world, ticks are the main vectors in Europe.

The tiger mosquito. Only the female mosquito bites. Depending on the species, females are attracted to mammals, birds or even cold-blooded animals such as frogs and snakes. The tiger mosquito (Aedes albopictus) prefers human blood; it is therefore said to be "anthropophilic". Present in more than 100 countries on five continents and in 58 départements in mainland France, it can transmit viruses such as dengue, chikungunya and Zika to humans. >> Twelve questions on the tiger mosquito.

 

Ticks belong to the subclass Acari. In our part of the world, they are found mainly in wooded areas in spring and summer. In Europe, they are the most common vectors of pathogens (bacteria, viruses and parasites) responsible for infectious diseases in humans and animals. In France, the main human disease associated with ticks is Lyme disease. >> Find out more about ticks.


3 ➡ Vector-borne diseases in animals or plants

enlightened Did you know? There are a multitude of vectors involved in diseases that affect only animals or plants. Here we take a closer look at four diseases.

Bluetongue is a viral disease of ruminants, and does not affect humans or food. It is transmitted by midges and can cause major economic losses in animal husbandry. >> Five questions on bluetongue.

African Swine Fever (ASF) is a viral haemorrhagic disease that affects domestic pigs and wild boar but cannot be transmitted to humans. It represents a major threat to the production sectors concerned. Although the primary mode of transmission is direct contact with an infected animal, the virus can also be transmitted through the bite of ticks of the genus Ornithodoros. >> Focus on ticks, the subject of multiple studies.

Xylella fastidiosa is a bacterium currently able to infect nearly 600 plant species, with an impact on major agricultural sectors. It is transmitted by xylem-feeding insect vectors. About thirty species of leafhoppers feed on rising xylem sap and can therefore potentially transmit the bacterium in France. >> What is Xylella fastidiosa?

The pinewood nematode is a microscopic worm that infests certain trees of the conifer family, in particular maritime pines. It is a particularly destructive parasite responsible for severe dieback in pine forests. Transmitted by a beetle, its spread is mainly due to the transport of timber or plants. >> Find out more about the pine wood nematode.


4 ➡ Control strategies and research on innovation

There is usually no vaccine nor any specific treatment against the pathogens responsible for these vector-borne diseases, and the main solution to managing these diseases is therefore to control the arthropods that carry them. ANSES assesses the effectiveness of insecticides and the risks associated with their use. It also funds research into other means of controlling insect vectors.

>> Find out more about the issues associated with vector control and ANSES's work.

The use of chemical insecticides against mosquitoes, with its successes and failures, is a typical example of the challenges that must be overcome by research in order to prepare future vector control strategies. The Agency develops research activities by funding projects dedicated to furthering knowledge of vectors or vector control, via the National Research Programme for Environmental and Occupational Health.

>> Follow the webinar on new prospects for vector control.

The ANSES laboratories also study vector-borne diseases transmitted to animals and the ability of vectors to transmit these pathogens. >> Find out more about the laboratories' research work on vectors.