Genetic evidence of spotted fever group rickettsiae in ticks collected
from domestic animals in Eastern Cape, South Africa.
Background: Ticks have the propensity to transmit plethora of pathogens
that have zoonotic potentials. Their distribution, diversity and the
pathogens they transmit differs from one ecological location to another.
SFG (spotted fever group) rickettsiae which are predominantly
transmitted by different Ixodes ticks are responsible for emerging
zoonotic diseases globally. Ticks were collected from domesticated
animals in Raymond Nkandla Municipality, Eastern Cape, South Africa. The
ticks were identified morphologically prior to DNA extraction and were
molecularly identified by randomly selecting ticks from the
morphologically delineated groups. To assess for the presence of
tick-borne pathogens belonging to Rickettsia spp. by PCR (polymerase
chain reaction) we used specific primer pairs targeting the gltA, ompA
and ompB genes. The selected amplified ticks (according to morphological
delineations), all positive ompB and forty three ompA amplicons were
sequenced in a commercial sequencing facility. The obtained nucleotide
sequences were edited and subjected to BLASTn for homology search and
phylogenetic analyses were performed with MEGA 7 Version for
evolutionary relationships with curated reference sequences in GenBank.
Results: A total of 953 ticks collected in the study were delineated
into three genera consisting of Amblyomma, Rhipicephalus and Hyalomma in
decreasing order of abundance. The presence of Rickettsia DNA was
detected in 60/953 (6.3%) from the three genera of ticks screened.
Genetic analyses of the DNA sequences obtained showed that they have
phylogenetic relationship to members of spotted fever group rickettsiae
with R. africae, R. parkeri and R.tamurae being the SFGR (spotted fever
group rickettsiae) detected in the screened ticks. Conclusion: This
report shows that R. africae is the predominant spotted fever group
rickettsiae in ticks collected from domestic animals in the study area
and the human health impacts are not known.