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Sheep tick (Ixodes ricinus). © INRA, CHAUBET Bernard

Tick-fighting tactics

New tick species discovered in southern France

Researchers have found a new tick species in southern France. The tick is a potential vector of emerging pathogens, including Crimean-Congo hemorrhagic fever. Consequently, its prevalence, especially in horses (a sentinel species), must be monitored.

By Pascale Mollier, translated by Jessica Pearce
Updated on 05/19/2017
Published on 12/02/2016

Cheval de Camargue.. © INRA, CATTIAU Gilles
Cheval de Camargue. © INRA, CATTIAU Gilles

The Camargue, France’s largest wetland, is located in the delta of the Rhone River. It is populated by horses, cattle, and around 400 species of birds. It is also home to some less savory inhabitants—ticks. Ticks are the world’s number-one vector of animal diseases and are second only to mosquitoes in transmitting human diseases.

Between 2007 and 2015, ticks were sampled several times in the Camargue with the goal of monitoring the transmission of several pathogens (1). In the course of this work, a new tick species was discovered: Hyalomma marginatum. In 2012 and 2013, the French Directorate General for Food (DGAL) carried out field research specifically targeting this species and then, in 2016, looking at its occurrence within bird and horse populations. It was discovered that H. marginatum has become established in the Camargue, as well as along the western coast and in heath habitat (garrigue) near Montpellier. To carry out this research, INRA and CIRAD scientists have been working closely with veterinarians and horse owners in the region.

Evidence of Hyalomma marginatum in southern France

Hyalomma marginatum is taxonomically distinguished by its large size and striped legs. It is the only member of its genus with these characteristics in the region. While the species is common in North Africa, Portugal, and Corsica, it was observed in the Camargue for the first time in 2008: immature stages—larvae and nymphs—were found on migrating bird species. In 2016, all tick stages were observed, and larvae and nymphs were found on non-migratory bird species. Furthermore, adult ticks occurred on horses, wild boars, and even humans. CIRAD scientist Laurence Vial (2) comments, “We think that this tick has been in southern continental France for 10 years. Climatic conditions have become more favorable—winter temperatures are milder and humidity levels are not too high—allowing it to complete its life cycle and reproduce. It also has access to an abundance of hosts.”

A tick capable of vectoring human and animal pathogens

Hyalomma marginatum tick. © INRA, Laurence Vial (Cirad) et Laurent Soldati (Inr
Hyalomma marginatum tick © INRA, Laurence Vial (Cirad) et Laurent Soldati (Inr

Of the pathogens that H. marginatum can vector, Crimean-Congo hemorrhagic fever (CCHF) is of particular concern. CCHF is endemic in Africa and Asia, although three human cases have now been observed in Europe: one in Greece in 2008 and two in Spain in 2016. These individuals were infected in Europe, not abroad, and one of the Spanish victims died. This virus is dangerous and hard to isolate and grow. Also, studying it requires strict biosafety precautions. As a consequence, CCHF remains poorly characterized.

Horses should be carefully monitored because they are one of H. marginatum’s preferred hosts and frequently travel between France and Spain. Generally speaking, CCHF viremia is limited in horses, which means that they are poor vehicles for transmitting the disease to humans and only rarely promote tick reinfection. However, horses could be very useful in monitoring efforts because they are good sentinels: although CCHF infections in horses are always asymptomatic, high levels of antibodies are produced. At present, there is no reason to think that CCHF is circulating elsewhere in France.

Epidemiological monitoring and regulatory considerations

“It would be helpful to monitor the serology of horses, as well as that of other potential sentinel species, and to track virus circulation (which is actually unlikely). First, we would do some baseline sampling and then we would perform additional sampling at regular intervals. We could also confirm the presence of CCHF in ticks using PCR. These efforts would allow us to determine the degree of surveillance we should put in place. However, for this to happen, regulations need to change so that we could carry out routine serological analyses involving CCHF in research laboratories that do not have a Biosafety Level 4 ranking (which is complicated and expensive to obtain); of course, all necessary precautions would still be followed. We are currently discussing this possibility with the French National Agency for Medicine and Health Product Safety (ANSM). Furthermore, it is crucial to get informed consent from livestock owners and other important stakeholders,” explains Vial.

A monitoring network focused on horse epidemics

Veterinarians and horse farmers in the Camargue are now linked with researchers via a monitoring network that was established by Agnès Leblond (3) and Sophie Pradier (4). “This network already plays a major role in monitoring diseases such as West Nile, Q fever, piroplasmosis (5), and equine granulocytic anaplasmosis. It is a valuable long-term tool that has allowed us to establish trust-based collaborations with farmers,” says Leblond. Sociological research has also been launched to study risk perception in farmers and thus inform policymakers as to the factors underlying vaccination choices by horse owners, especially with regards to West Nile virus. To be able to interpret monitoring results in the region, it is essential to characterize immunization coverage.


(1) Such pathogens include the bacterial species Anaplasma phagocytophilum, which causes anaplasmosis, and Coxiella burnetii, which is responsible for Q fever. For example, A.  phagocytophilum infects white blood cells, resulting in thrombocytopenia.

(2) CMAEE Joint Research Unit, CIRAD, Montpellier

(3) IHAP Joint Research Unit, University of Toulouse, INRA, National Veterinary School of Toulouse

(4) EPIA Joint Research Unit, INRA, VetAgroSup

(5) Piroplasmosis can be caused by either Theileria equi or Babesia caballi, which infect red blood cells and cause hemolytic anemia.

Scientific contact(s):

Associated Division(s):
Animal Health
Associated Centre(s):
Auvergne Rhône-Alpes


Vial L, Stachurski F, Leblond A, Huber K, Vourc'h G, René-Martellet M, Desjardins I, Balança G, Grosbois V, Pradier S, Gély M, Appelgren A, Estrada-Peña A. 2016. Strong evidence for the presence of the tick Hyalomma marginatum Koch, 1844 in southern continental France. Ticks Tick Borne Dis. 2016 Oct;7(6):1162-1167. doi: 10.1016/j.ttbdis.2016.08.002. Epub 2016 Aug 6.

Did France go too far in its 2000 response to West Nile?

In 2000, an outbreak of West Nile (1) was reported in the horse population found between Aigues Mortes and Montpellier. Around 70 horses were affected, and varied measures were taken, including the release of an official declaration of infection (APDI) for each residence or business where infection was found. Infected horses were prohibited from traveling. Although these restrictions were loosened in subsequent years, professionals in the horse industry had a difficult time. Courses were cancelled, and some equestrian centers even went under. The result was major economic losses, an unfortunate outcome given that horses are not contagious and represent a dead end host. It is therefore crucial to establish clear risk evaluation methods to build trust-based relationships with farmers.
(1) West Nile virus is transmitted to humans via mosquitoes. The virus causes fevers and can result in neurological symptoms, which may be quite severe in many animal species.