Molecular epidemiology of spotted fever group rickettsioses and Q fever at the wildlife-livestock interface in Maasai Mara and Laikipia ecosystems, Kenya

Abstract

Spotted fever group (SFG) rickettsioses and Q fever are zoonotic diseases caused by the intracellular bacteria in the genus Rickettsia and Coxiella burnetii respectively. The pathogens continue to be described in livestock and their ticks in Kenya yet no information is available about them in wildlife and their ticks. This is despite wildlife having been identified as important sources of zoonotic pathogens. This study investigated the presence, prevalence and species of SFG Rickettsia species and strains of C. burnetii in wildlife and their ticks in Laikipia and Maasai Mara ecosystems. It also evaluated the knowledge, attitudes and practices (KAP) of the local residents towards the diseases. A total of 152 animals (79 in Laikipia and 73 in Maasai Mara) comprising 8 species were sampled and 851 ixodid ticks comprising 10 species collected from the animals. The ticks were pooled into 166 pools (137 in Laikipia and 29 in Maasai Mara) of 1-8 ticks according to species, sampling site and the animal host. To detect SFG Rickettsia species and C. burnetii, DNA extracted from EDTA blood and ticks was tested using real-time PCR targeting the intergenic spacer rpmE-tRNAfMet and the repetitive insertion element IS1111a of the transposase gene, respectively. To identify the SFG Rickettsia species, genes ompA, ompB and gltA were amplified and the PCR positive products sequenced. To identify the strains of C. burnetii, the insertion element IS1111a was sequenced in PCR positive products. The prevalence of SFG rickettsioses in wildlife was 2/79 (2.5%) in Laikipia and 4/73 (5.5%) in Maasai Mara. The prevalence in ticks was 30/137 (21.9%) in Laikipia and 5/29 (17.2%) in Maasai Mara. The detection was in 30/135 (22.2%) and 2/24 (8.3%) of Rhipicephalus ticks sampled in Laikipia and Maasai Mara respectively, and 2/2 (100%) of Amblyomma and 1/3 (33.3%) of Hyalomma ticks sampled in Maasai Mara. In regard to individual tick species, the detection was in 4/11 (36.4%) of Rh. evertsi, 16/53 (30.2%) of Rh. appendiculatus, 6/33 (18.2%) of Rh. pulchellus and 4/38 (10.5%) of Rh. evertsi evertsi ticks sampled in Laikipia. In Maasai Mara, 2/10 (20%) Rh. appendiculatus and the only sample each of H. dromedari, A. variegatum and A. truncatum tested positive. Sequence analyses of amplified genes of SFG rickettsiae revealed R. sibirica in a Topi (Damaliscus korrigum), Rh. evertsi evertsi, Rh. appendiculatus, A. xvi variegatum and A. truncatum as well as R. sibirica subspecies mongolotimonae in Rh. evertsi, Rh. pulchellus, A. variegatum and A. truncatum ticks. C. burnetii DNA was not detected in any of the animals. The prevalence in ticks was 4/137 (2.9%) in Laikipia. The pathogen was detected in 4/135 (3.0%) of Rhipicephalus ticks at prevalence of 2/53 (3.8%) in Rh. appendiculatus, 1/33 (3.0%) in Rh. pulchellus and 1/38 (2.6%) in Rh. evertsi evertsi. No ticks tested positive in Maasai Mara. Sequence analyses revealed the isolates to be identical and had 100% similarities to strains from other parts of the world. To evaluate the KAP, a semi-structured questionnaire was administered to 101 respondents comprising 51 pastoralists, 17 human health providers, 28 wildlife sector personnel and 5 veterinarians. Thirteen out of 22 (59.1%) pastoralists in Laikipia and 18/29 (62.1%) in Maasai Mara were aware that some tick-borne diseases can infect humans but expressed low level of knowledge on SFG rickettsioses. Eleven out of 22 (50%) pastoralists in Laikipia and 16/29 (55.2%) in Maasai Mara expressed knowledge on non tick-borne zoonotic diseases but expressed no knowledge about Q fever. Six out of 15 (40%) wildlife sector personnel in Laikipia and 2/13 (15.4%) in Maasai Mara expressed knowledge on tick-borne zoonoses and 4/15 (26.7%) in Laikipia expressed some knowledge about African tick-bite fever and none expressed any knowledge on Q fever in both study areas. Five out of 11 (45.5%) of the health providers in Laikipia and 2/6 (33.3%) in Maasai Mara expressed knowledge on tick-borne zoonoses including African tick-bite fever and 1/11 (9.1%) in Laikipia expressed good knowledge on Q fever and none in Maasai Mara. Only one medical facility in Laikipia finds it necessary to confirm SFG rickettsioses and Q fever in febrile patients and none in Maasai Mara. The veterinarians expressed some level of knowledge on both diseases. The study identified R. sibirica and R. sibirica subspecies mongolotimonae, two SFG rickettsial species not previously reported in Kenya in a Topi (Damaliscus korrigum) and Rh. evertsi evertsi, Rh. evertsi, Rh. pulchellus, A. variegatum and A. truncatum ticks. It also identified C. burnetii in Rh. appendiculatus, Rh. pulchellus and Rh. evertsi evertsi ticks. These findings demonstrate that wildlife and their ticks play a potential role in the epidemiology of these pathogens in Laikipia and Maasai Mara ecosystems. The study recommends that the role of these pathogens as causes of febrile illness in local residents in both areas be evaluated.