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Updated: Oct 15, 2025
Feeding of Ticks on Animals for Transmission and Xenodiagnosis in Lyme Disease Research
Published on: August 31, 2013
Rickettsia lusitaniae in Ornithodoros Porcinus Ticks, Zambia
Simbarashe Chitanga1,2,3, Herman M Chambaro4,5, Lavel C Moonga4
1Department of Paraclinical Studies, Faculty of Health Sciences and Veterinary Medicine, School of Veterinary Medicine, University of Namibia, Windhoek Private Bag 13301, Namibia.
Abstract:
Rickettsial pathogens are amongst the emerging and re-emerging vector-borne zoonoses of public health importance. Though traditionally considered to be transmitted by ixodid ticks, the role of argasid ticks as vectors of these pathogens is increasingly being recognized. While bat-feeding (Ornithodoros faini) and chicken-feeding (Argas walkerae) argasid ticks have been shown to harbor Rickettsia pathogens in Zambia, there are currently no reports of Rickettsia infection in southern Africa from warthog-feeding (Phacochoerus africanus) soft ticks, particularly Ornithodoros moubata and Ornithodoros porcinus. Our study sought to expand on the existing knowledge on the role of soft ticks in the epidemiology of Rickettsia species through screening for Rickettsia pathogens in warthog burrow-dwelling soft ticks from two national parks in Zambia. The tick species from which Rickettsia were detected in this study were identified as Ornithodoros porcinus, and an overall minimal Rickettsia infection rate of 19.8% (32/162) was observed. All of the sequenced Rickettsia were identified as Rickettsia lusitaniae based on nucleotide sequence similarity and phylogenetic analysis of the citrate synthase (gltA) and 17kDa common antigen (htrA) genes. Utilizing all of the gltA (n = 10) and htrA (n = 12) nucleotide sequences obtained in this study, BLAST analysis showed 100% nucleotide similarity to Rickettsia lusitaniae. Phylogenetic analysis revealed that all of the Zambian gltA and htrA gene sequences could be grouped with those of Rickettsia lusitaniae obtained in various parts of the world. Our data suggest that Rickettsia lusitaniae has a wider geographic and vector range, enhancing to our understanding of Rickettsia lusitaniae epidemiology in sub-Saharan Africa.
Insights
This study identified Rickettsia lusitaniae in warthog-feeding soft ticks (Ornithodoros porcinus) in Zambia, expanding knowledge of this pathogen
Area of Science:
- Veterinary Entomology
- Zoonotic Disease Epidemiology
- Molecular Microbiology
Background:
- Rickettsial pathogens are significant emerging vector-borne zoonoses.
- While hard ticks are known vectors, soft ticks (argasid ticks) are increasingly recognized.
- Previous studies in Zambia identified Rickettsia in bat and chicken-feeding ticks, but not warthog-feeding ticks.
Purpose of the Study:
- To investigate the presence of Rickettsia pathogens in soft ticks that feed on warthogs in Zambian national parks.
- To expand the understanding of soft tick roles in Rickettsia epidemiology in southern Africa.
Main Methods:
- Screening of warthog burrow-dwelling soft ticks for Rickettsia pathogens.
- Molecular identification of tick species and Rickettsia species using citrate synthase (gltA) and 17kDa common antigen (htrA) genes.
- Phylogenetic analysis and BLAST searches for sequence similarity.
Main Results:
- Rickettsia pathogens were detected in Ornithodoros porcinus ticks.
- An overall minimal Rickettsia infection rate of 19.8% (32/162) was observed.
- All sequenced Rickettsia were identified as Rickettsia lusitaniae, showing 100% nucleotide similarity to global strains.
Conclusions:
- Ornithodoros porcinus ticks in Zambia harbor Rickettsia lusitaniae.
- This finding suggests Rickettsia lusitaniae has a broader geographic and vector range than previously known.
- The study enhances understanding of Rickettsia lusitaniae epidemiology in sub-Saharan Africa.
