Assay of fipronil efficacy to prevent canine monocytic ehrlichiosis in endemic areas.
Our objective was to evaluate the efficacy of fipronil for the prevention of Ehrlichia canis transmission to dogs by Rhipicephalus sanguineus in two endemic areas situated in Africa (Dakar and Djibouti). We carried out controlled trials in kennels for 1 year on 248 dogs, mainly police dogs and military working dogs. Eight groups were studied in a multi-centre study. Fifty five fipronil treated dogs were located in two separated kennels (G3, 37 dogs in Djibouti and G8, 18 dogs in Dakar). G1 (66 dogs) and G2 (60 dogs) were untreated control groups located in Djibouti, whereas G4 (32 dogs), G5 (13 dogs), G6 (18 dogs) and G7 (4 dogs) were the control groups located in Dakar. The epidemiological status of each group is known. G1 and G2 dogs were not kept in kennels, whereas G3, G4, G5, G6, G7, G8 dogs were housed in equivalent kennels. Tick infestation, clinical status and Ehrlichia seroprevalence were assessed during 1 year (duration of the study). Dog treated with fipronil showed neither canine monocytic ehrlichiosis (CME) nor tick infestations. In all groups of untreated control animals, R. sanguineus tick infestations were frequent, particularly in kennels (G5, G6 and G7) as well as morbidity and mortality due to CME. E. canis infection rates were low for fipronil treated animals: 2.7% (1/37) for G3 and 5.5% (1/18) for G8 group. Among control animals, seroprevalence was maximum (100%) in dogs kept in kennels (G5, G6 and G7 groups) and high among native dogs in Djibouti (G1 group): 69.7% (46/66) and in Dakar (G4 group): 50% (16/32). Dogs belonging to expatriate citizens (G2 group) were less likely to be infected: 21.7% (13/60). The comparison of serological results among French army dogs and French citizen dogs that were introduced in Djibouti for an average of 10 months shows a statistically significant (P<0.001) difference. Among fipronil treated animals (G3 group), 2 dogs out of 55 seroconverted (3.6%) compared to 13 out of 60 dogs (21.7%) in the control G2 group. The results of our study indicate the preventative efficacy of a fipronil monthly treatment to avoid CME in endemic areas. Epidemiological data concerning animals that live in the same endemic areas are an example of the serious consequences (in terms of mortality and morbidity) that are related to the absence of efficient methods for tick-control. In order to protect dogs that are in transit in endemic areas against tick-transmitted diseases, the use of an adapted acaricide product is recommended.
Davoust
B
B
Direction Régiónale du Service de Santé des Armées, BP 16, Armées, 69998 Lyon, France. bernard.davoust@mageos.com
Marié
J L
JL
Mercier
S
S
Boni
M
M
Vandeweghe
A
A
Parzy
D
D
Beugnet
F
F
D000349:Africa; D000818:Animals; D001179:Arthropod Vectors / Q000187:drug effects; D004283:Dog Diseases / Q000469:parasitology / Q000517:prevention & control* / Q000635:transmission; D004285:Dogs; D041061:Ehrlichia canis / Q000187:drug effects; D016873:Ehrlichiosis / Q000469:parasitology / Q000517:prevention & control* / Q000635:transmission / Q000662:veterinary*; D007306:Insecticides / Q000008:administration & dosage / Q000494:pharmacology*; D011720:Pyrazoles / Q000008:administration & dosage / Q000494:pharmacology*; D016036:Seroepidemiologic Studies; D013984:Tick Infestations / Q000517:prevention & control / Q000635:transmission; D013987:Ticks / Q000187:drug effects
D007306:Insecticides; D011720:Pyrazoles; C082360:fipronil