Jacquiet P.1, Alzieu J.P.2, Desclaux X.2, Rameil M.2, Malavieille

Jacquiet P.1, Alzieu J.P.2, Desclaux X.2, Rameil M.2, Malavieille R.2,
Prévot F.1,Grisez C.1, Liénard E.1, Bouhsira E.1, Franc M.1 ,
Boulon C.3, Deltour B.4
1. National Veterinary School of Toulouse, INRA IHAP 1225, France
2. Laboratoire Vétérinaire Départemental de l’Ariège, Foix, France
3. Groupement de Défense Sanitaire de l’Ardèche, Privas, France
4. Groupement de Défense Sanitaire de la Drôme, Valence, France
European Buiatrics Forum 2013, Marseille, 28 novembre 2013
Bovine besnoitiosis : emergent disease
in France and Europe (EFSA 2010)
Enzootic area
Emergence
Until 1990
In 2013…
How to stop the spread ?
In newly infected farms, the annual costs per animal varied from 40 to 60 euros
To stop the spread of bovine besnoitiosis,
we have to understand the routes of transmission
n 
Cats and wild carnivores are not definitive
hosts in Europe
(Diesing et al., 1988; Basso et al., 2011, Millan et al., 2011)
n 
Bovine besnoitiosis: a vector-borne disease
q 
Mechanical transmission / stable flies and tabanids
(Bigalke, 1968; Liénard et al., 2013)
n 
In addition, no reservoir in the wild fauna
(Gutierrez-Exposito et al., 2013)
n 
No vertical infection, no parasite DNA in the
semen of infected bulls
(Jacquiet, unpublished)
Infection
Mainly serology
Oedema
phase
Fébrile
phase
To stop the spread of bovine besnoitiosis,
we need to detect all infected animals … (1)
1
week
2
week
Chronic (scleroderma) phase
4
week
5
week
6
week
2
months
3
months
6
months
PCR on blood
PCR on skin biopsy
Western Blot
ELISA
To stop the spread of bovine besnoitiosis,
we need to detect all infected animals … (2)
q 
Tachyzoite-based Western blot test
n 
n 
q 
= reference test
very high specificity and high sensitivity
ELISA kits
n 
n 
2 commercially available kits evaluated
by using a reference collection of sera
(N = 452) in France
PrioCheck Besnoitia Ab (Prionics)
q 
n 
Sp: 100,0%
IdVet Besnoitia (IdVet)
q 
q 
Se: 97,0%
Se: 90,5%
Sp: 99,7%
PCR : interesting tool
n 
but inconstant results according to presence
of parasite in blood or skin samples
Our main hypothesis explaining the spread of
bovine besnoitiosis in France :
n 
Introduction of a chronically
infected animal in a previously
Besnoitia-free farm
n 
Followed by transmission by
stable flies and tabanids,
mostly during the grazing
period
How to control bovine besnoitiosis ?
Key points
To maintain
herds
“Besnoitia free “
Serological
Control
of all animals
prior to entry
Complete
Serological
screening
in an infected herd
Selective culling
of clinical cases
and seropositive
animals
Example of study control
Pilot project
in southeastern France
Pilot project (1) : serological control
of introductions in cattle herd
n 
On a voluntary basis
n 
1104 animals (commercial trades) tested in ELISA / WB
(from January 2012 to June 2013)
n 
n 
12 infected animals were detected
8 cattle farms have been protected !
n 
Total costs of the analyses : 9-10 euros / introduced animal
Source : FRGDS Rhône-Alpes, France
Pilot project (2) : evaluation of the efficacy
of a selective culling program
n 
Area of emergence in southeastern France
q 
11 beef cattle farms
(Charolais, Aubrac et Salers breeds)
were included in the control program
q 
q 
q 
q 
Adjoining farms
but no common pastures, no transhumance
First clinical cases in 2003 in one farm
2004 - 2009 : clinical cases were observed in six
other farms
In fact, all the 11 cattle farms were infected
Step one : evaluation of the initial serological
prevalences (March 2010), PrioCheck Besnoitia Ab ® + WB
Seroprevalence (%)
70
60
50
40
30
20
10
0
1
2
3
4
5
6
7
8
9
10
11
Farms
In this area of emergence, seroprevalences are highly variable
Control strategies applied
Low
High
seroprevalence
seroprevalence
(< 10%)
(> 10%)
Insecticide treatments
+
Rapid and total culling
of seropositive animals
+ protection against
entry of positive animals
Insecticide treatments
+ Physical separation
of seroPos and seroNeg,
(proposed but not achieved)
Step two : annual incidences (%) of B. besnoiti
infections (evaluated by serological conversions)
Farm
Initial
seroprevalence
(%)
Incidence (%)
2010 – 2011
Incidence (%)
2011 – 2012
Incidence (%)
2012 – 2013
1
57
53
58
80
2
42
54
17
61
3
4
0
0
0
4
2
0
0
0
5
45
49
10
79
6
2
0
0
0
7
13
49
50
53
8
53
82
55
77
9
25
30
32
54
10
58
78
56
58
11
4
0
0
0
In farms where the total culling of seropositive animals was achieved,
no recontamination occurs from the adjoining highly infected farms
during three successive seasons of pasture
despite …
… close proximity
of farms !!!
F7
Pilote project area
F3
F2
Infected farms
5 km
Non infected farm
F5
F8
F9
F11
F4
F1
F6
F10
March 2013
Conclusions (1)
n 
The epidemiology of bovine besnoitiosis seems
very different from those of BTV or Schmallenberg virus
infections !
à mechanical transmission versus biological vectors
n 
Sanitary status versus Besnoitiosis may be managed
farm by farm
n 
Insect control strategies failed to slow down the spread in
heavily infected farms…
q 
q 
optimal pyrethroïds dosage and rhythms of administration
are not well known to control stable flies and horse flies in cattle
resistance of stable flies to pyrethroïds was recently demonstrated
in France (Salem et al., 2012)
Conclusions (2)
n 
As no effective treatment and no vaccines
are actually available…
n 
Options of control are limited to :
q 
q 
imperative serological control prior entry into
Besnoitia-free herds.
complete serological screening as soon as
possible to apply a culling program, according to
the seroprevalence in infected herds.
Acknowledgements
n 
Fédération Régionale des Groupements de
Défense Sanitaire de Rhône-Alpes
n 
Cattle breeders in Ardèche and Drôme
n 
FNGDS France “Besnoitiosis Project”
Thank you for your attention