Spotted Fever Group Rickettsiae in Ticks From the Masai Mara Region of Kenya

Abstract

Abstract. We have identified for the first time Rickettsia africae, and the ticks that harbored them, in Kenya. A total of 5,325 ticks were collected from vegetation, livestock, and wild animals during two field trips to southwestern Kenya. Most were immature forms (85.2%) belonging to the genera Amblyomma or Rhipicephalus. The adults also included representatives from the genus Boophilus. Ticks were assessed for rickettsial DNA by a polymerase chain reaction (PCR) using primers for the spotted fever group (SFG)-specific rickettsial outer membrane protein A (rompA) gene, and positive amplicons were sequenced. While none of the immature ticks tested positive by PCR, 15.8% of the adult Amblyomma variegatum and less than 1% of the Rhipicephalus spp. were SFG positive. Sequences of amplified products were identified as R. africae. These findings extend the known range of R. africae.

High Prevalence ofRickettsia africaeVariants inAmblyomma variegatumTicks from Domestic Mammals in Rural Western Kenya: Implications for Human Health

“…R. africae variants have previously been detected in A. variegatum ticks collected in various countries in Africa, namely Niger, Mali, Sudan, Burundi, and Mauritania (Parola et al 2001). On the basis of the nucleotide sequences of the ompA gene, two of 10 (Macaluso et al 2003). Uncultured Rickettsia spp.…”

“…In East Africa, R. africae was previously detected in 16% of adult A. variegatum ticks in southwestern Kenya (Macaluso et al 2003). A fatal case of spotted fever rickettsiosis in an expatriate in Kenya was attributed to R. conorii infection, the causative agent of Mediterranean spotted fever (MSF), on the basis of the severity of the disease (Rutherford et al 2004), and a laboratory-confirmed case of MSF occurred in a Japanese traveler to Kenya (Yoshikawa et al 2005).…”

Spotted fever group rickettsiae in ixodid ticks in Oromia, Ethiopia

“…(Bo.) decoloratus is infected only when cohabiting with Amblyomma ticks, regarded as the primary reservoir of R. africae (Macaluso et al, 2003;Mediannikov et al, 2013). R. africae has also been reported in Rh (Bo.)…”

Tick-Borne Rickettsioses around the World: Emerging Diseases Challenging Old Concepts

“…Frequent human cases may be attributed to efficient transovarial transmission of the agent when larvae, which are small and difficult to notice when attached to the skin, are involved as vectors. R. africae has also been detected in A. variegatum throughout west, central, and eastern sub-Saharan Africa (181,242) and in A. lepidum from the Sudan (242). Three uncultivated rickettsiae, named Rav1, Rav3, and Rav9, detected by PCR from A. variegatum ticks in Niger and Mali, appear to be closely related, probably variants of R. africae, based on molecular analyses of the ompA and gltA genes (242).…”