Molecular Detection of in Small Mammals and Infesting Ticks in Laikipia County, Kenya.

Anaplasmosis is a set of disease conditions of various mammals caused by bacteria species of the genus . These are sub-microscopic, Gram-negative, obligate intracellular pathogens that infect both vertebrate and invertebrate hosts. Significant species that infect domestic and wildlife animals include , , and . Although . has a widespread distribution, there are only a few epidemiological reports from sub-Saharan Africa. This study focused on molecular detection and characterization of in small mammals and their infesting ticks in Laikipia County, Kenya. A total of 385 blood and 84 tick archival samples from small mammals (155 females and 230 males) were analyzed. The blood samples were subjected to a nested PCR-HRM melt analysis using species-specific primers to amplify the 16S ribosomal RNA genes. The ticks were also subjected to nested PCR-HRM involving 16S rRNA gene primers. DNA was detected in 19 out of 385 samples using species-specific 16S rRNA gene primers giving a prevalence of 4.9% for . Analysis of the tick's samples using 16S rRNA gene species-specific primers also detected in 3 samples from ticks (3/84) equivalent to prevalence of 3.6%. Sequencing of 16S rRNA PCR products confirmed in small mammals and ticks' samples. Phylogenetic analysis of the haplotype from this study demonstrated a close ancestral link with strains from , and ticks () reported in Europe, China, and Africa. Comparison was also made with a known pathogenic . variant HA and a nonpathogenic variant 1 that were clustered into a distinctive clade different form haplotypes detected in this study. All the haplotype sequences for from this study were submitted and registered in GenBank under the accession numbers OQ308965-OQ308976. Our study shows that small mammals and their associated ticks harbor . The vector competence for . in transmission should further be investigated.