Molecular Detection of Previously Unknown Anaplasma Genotype in Cattle from Uganda

The genus Anaplasma includes some of the most economically important tick-borne pathogens of cattle in sub-Saharan African. The main objective of this study was therefore to identify Anaplasma species/genotypes circulating in cattle from Kumi and Kiruhuura Districts in eastern and southwestern regions of Uganda respectively where only A. marginale has been reported to exist based on serological detection and/or microscopy. Nine farms, 5 from Kumi and 4 from Kiruhuura were randomly selected and blood samples collected from apparently normal calves (<1 year) and adult cattle (>2.5 years). The species- specific oligonucleotide probes based on the differences within the hypervariable V1 region of the 16S rRNA gene were used to detect Anaplasma organisms in blood. From this study, previously unknown Anaplasma genotype, closely related to A. marginale but not hybridizing with A. marginale-specific oligonucleotide probe was detected from eastern Uganda. This genotype showed nucleotide differences with the known Anaplasma species at the hypervariable V1 region. In addition A. bovis and A. marginale were detected in cattle from both regions while A. centrale was detected only in cattle from southwestern Uganda. The Anaplasma infections were detected only in adult cattle. This indicates possible high diversity of Anaplasma in these regions of Uganda. The previously unknown genotype may be a different Anaplasma species or a variant of A. marginale. We suggest the use of the heat shock operon (groESL), citrate synthase (gltA) and surface protein genes to further characterize this Anaplasma genotype.