The epidemiology and geographic distribution of relapsing fever borreliosis in West and North Africa, with a review of the Ornithodoros erraticus complex (Acari: Ixodida).
BACKGROUND
Relapsing fever is the most frequent bacterial disease in Africa. Four main vector / pathogen complexes are classically recognized, with the louse Pediculus humanus acting as vector for B. recurrentis and the soft ticks Ornithodoros sonrai, O. erraticus and O. moubata acting as vectors for Borrelia crocidurae, B. hispanica and B. duttonii, respectively. Our aim was to investigate the epidemiology of the disease in West, North and Central Africa.


RESULTS
From 2002 to 2012, we conducted field surveys in 17 African countries and in Spain. We investigated the occurrence of Ornithodoros ticks in rodent burrows in 282 study sites. We collected 1,629 small mammals that may act as reservoir for Borrelia infections. Using molecular methods we studied genetic diversity among Ornithodoros ticks and Borrelia infections in ticks and small mammals. Of 9,870 burrows investigated, 1,196 (12.1%) were inhabited by Ornithodoros ticks. In West Africa, the southern and eastern limits of the vectors and Borrelia infections in ticks and small mammals were 13°N and 01°E, respectively. Molecular studies revealed the occurrence of nine different Ornithodoros species, including five species new for science, with six of them harboring Borrelia infections. Only B. crocidurae was found in West Africa and three Borrelia species were identified in North Africa: B. crocidurae, B. hispanica, and B. merionesi.


CONCLUSIONS
Borrelia Spirochetes responsible for relapsing fever in humans are highly prevalent both in Ornithodoros ticks and small mammals in North and West Africa but Ornithodoros ticks seem absent south of 13°N and small mammals are not infected in these regions. The number of Ornithodoros species acting as vector of relapsing fever is much higher than previously known.
Institut de recherche pour le développement, Laboratoire de Paludologie Et Zoologie Médicale, Dakar, Senegal.
Jean-François
JF
Trape
Georges
G
Diatta
Céline
C
Arnathau
Idir
I
Bitam
M'hammed
M
Sarih
Driss
D
Belghyti
Ali
A
Bouattour
Eric
E
Elguero
Laurence
L
Vial
Youssouph
Y
Mané
Cellou
C
Baldé
Franck
F
Prugnolle
Franck
F
Pugnolle
Gilles
G
Chauvancy
Gil
G
Mahé
Laurent
L
Granjon
Jean-Marc
JM
Duplantier
Patrick
P
Durand
François
F
Renaud
D000349:Africa / Q000453:epidemiology; D000818:Animals; D001898:Borrelia / Q000145:classification / Q000472:pathogenicity / Q000502:physiology*; D004199:Disease Vectors; D006364:Hedgehogs / Q000382:microbiology / Q000469:parasitology; D006801:Humans; D026861:Ornithodoros / Q000145:classification / Q000382:microbiology*; D010802:Phylogeny; D012061:Relapsing Fever / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D012377:Rodentia / Q000382:microbiology / Q000469:parasitology; D013984:Tick Infestations / Q000453:epidemiology* / Q000382:microbiology