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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
agricultural and biological sciences
High prevalence of spotted fever group rickettsiae in Amblyomma variegatum from Uganda and their identification using sizes of intergenic spacers
Ticks and Tick-borne Diseases, Volume 4, No. 6, Year 2013
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Description
The spotted fever group (SFG) rickettsiae are obligate intracellular bacteria transmitted by ticks that cause several tick-borne rickettsioses in humans worldwide. This study was intended to determine the prevalence of SFG rickettsiae in Amblyomma variegatum from 7 districts across Uganda. In addition to sequencing of gltA and ompA genes, identification of Rickettsia species based on the sizes of highly variable intergenic spacers, namely, dksA-xerC, mppA-purC, and rpmE-tRNAfMet was carried out. Application of multiplex PCR for simultaneous amplification of 3 spacers combined with capillary electrophoresis separation allowed simple, accurate, and high-throughput fragment sizing with considerable time and cost savings. Rickettsia genus-specific real-time PCR detected 136 positives out of 140 samples, giving an overall prevalence of 97.1%. Most samples (n=113) had a size combination of 225, 195, and 341bp for dksA-xerC, mppA-purC, and rpmE-tRNAfMet, respectively, which was identical to that of R. africae, a causative agent of African tick bite fever. In addition, several samples had size variants in either dksA-xerC or rpmE-tRNAfMet. Nonetheless, the partial sequences of gltA and ompA genes of samples of all size combinations showed the greatest similarity to R. africae (99.3-100% for gltA and 98.1-100% for ompA). Given these results, it is highly possible that the tested ticks were infected with R. africae or closely related species. This is a first report on molecular genetic detection of R. africae and its high endemicity in Uganda. Clinicians in this country should be aware of this pathogen as a cause of non-malarial febrile illness. This study provided a starting point for the development of Rickettsia species identification based on the sizes of intergenic spacers. The procedure is simple, rapid, and cost-effective to perform; hence it might be particularly well suited for preliminary species identification in epidemiological investigations. The results may be more detailed and reliable when simultaneous sequencing analysis is performed. © 2013 Elsevier GmbH.
Authors & Co-Authors
Nakao, Ryo
Japan, Sapporo
Hokkaido University
Qiu, Yongjin
Japan, Sapporo
Hokkaido University
Igarashi, Manabu
Japan, Sapporo
Hokkaido University
Magona, Joseph W.
Japan, Sapporo
Hokkaido University
Uganda, Nakyesasa
National Livestock Resources Research Institute Nalirri
Zhou, Lijia
Japan, Sapporo
Hokkaido University
Ito, Kimihito
Japan, Sapporo
Hokkaido University
Sugimoto, Chihiro
Japan, Sapporo
Hokkaido University
Statistics
Citations: 36
Authors: 7
Affiliations: 2
Identifiers
Doi:
10.1016/j.ttbdis.2013.07.001
ISSN:
1877959X
e-ISSN:
18779603
Research Areas
Genetics And Genomics
Study Design
Cross Sectional Study
Study Locations
Uganda