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Djiman TA, Biguezoton AS, Saegerman C. Tick-Borne Diseases in Sub-Saharan Africa: A Systematic Review of Pathogens, Research Focus, and Implications for Public Health. Pathogens 2024; 13:697. [PMID: 39204297 PMCID: PMC11356977 DOI: 10.3390/pathogens13080697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 08/11/2024] [Accepted: 08/12/2024] [Indexed: 09/03/2024] Open
Abstract
Sub-Saharan Africa, with its hot and humid climate, is a conducive zone for tick proliferation. These vectors pose a major challenge to both animal and human health in the region. However, despite the relevance of emerging diseases and evidence of tick-borne disease emergence, very few studies have been dedicated to investigating zoonotic pathogens transmitted by ticks in this area. To raise awareness of the risks of tick-borne zoonotic diseases in sub-Saharan Africa, and to define a direction for future research, this systematic review considers the trends of research on tick-borne bacteria, parasites, and viruses from 2012 to 2023, aiming to highlight the circulation of these pathogens in ticks, cattle, sheep, goats, and humans. For this purpose, three international databases were screened to select 159 papers fitting designed inclusion criteria and used for qualitative analyses. Analysis of these studies revealed a high diversity of tick-borne pathogens in sub-Saharan Africa, with a total of 37 bacterial species, 27 parasite species, and 14 viruses identified. Among these, 27% were zoonotic pathogens, yet only 11 studies investigated their presence in humans. Furthermore, there is growing interest in the investigation of bacteria and parasites in both ticks and ruminants. However, research into viruses is limited and has only received notable interest from 2021 onwards. While studies on the detection of bacteria, including those of medical interest, have focused on ticks, little consideration has been given to these vectors in studies of parasites circulation. Regarding the limited focus on zoonotic pathogens transmitted by ticks, particularly in humans, despite documented cases of emerging zoonoses and the notable 27% proportion reported, further efforts should be made to fill these gaps. Future studies should prioritize the investigation of zoonotic pathogens, especially viruses, which represent the primary emerging threats, by adopting a One Health approach. This will enhance the understanding of their circulation and impact on both human and animal health. In addition, more attention should be given to the risk factors/drivers associated to their emergence as well as the perception of the population at risk of infection from these zoonotic pathogens.
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Affiliation(s)
- Tidjani A. Djiman
- Research Unit of Epidemiology and Risk Analysis Applied to Veterinary Sciences (UREAR-ULiège), Fundamental and Applied Research for Animals and Health (FARAH) Center, Faculty of Veterinary Medicine, University of Liege, 4000 Liège, Belgium;
- Vector-Borne Diseases and Biodiversity Unit (UMaVeB), International Research and Development Centre on Livestock in Sub-humid Areas (CIRDES), Bobo-Dioulasso 454, Burkina Faso;
| | - Abel S. Biguezoton
- Vector-Borne Diseases and Biodiversity Unit (UMaVeB), International Research and Development Centre on Livestock in Sub-humid Areas (CIRDES), Bobo-Dioulasso 454, Burkina Faso;
| | - Claude Saegerman
- Research Unit of Epidemiology and Risk Analysis Applied to Veterinary Sciences (UREAR-ULiège), Fundamental and Applied Research for Animals and Health (FARAH) Center, Faculty of Veterinary Medicine, University of Liege, 4000 Liège, Belgium;
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Khogali R, Bastos A, Bargul JL, Getange D, Kabii J, Masiga D, Villinger J. Tissue-specific localization of tick-borne pathogens in ticks collected from camels in Kenya: insights into vector competence. Front Cell Infect Microbiol 2024; 14:1382228. [PMID: 38698904 PMCID: PMC11063324 DOI: 10.3389/fcimb.2024.1382228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 03/15/2024] [Indexed: 05/05/2024] Open
Abstract
Background Tick-borne pathogen (TBP) surveillance studies often use whole-tick homogenates when inferring tick-pathogen associations. However, localized TBP infections within tick tissues (saliva, hemolymph, salivary glands, and midgut) can inform pathogen transmission mechanisms and are key to disentangling pathogen detection from vector competence. Methods We screened 278 camel blood samples and 504 tick tissue samples derived from 126 camel ticks sampled in two Kenyan counties (Laikipia and Marsabit) for Anaplasma, Ehrlichia, Coxiella, Rickettsia, Theileria, and Babesia by PCR-HRM analysis. Results Candidatus Anaplasma camelii infections were common in camels (91%), but absent in all samples from Rhipicephalus pulchellus, Amblyomma gemma, Hyalomma dromedarii, and Hyalomma rufipes ticks. We detected Ehrlichia ruminantium in all tissues of the four tick species, but Rickettsia aeschlimannii was only found in Hy. rufipes (all tissues). Rickettsia africae was highest in Am. gemma (62.5%), mainly in the hemolymph (45%) and less frequently in the midgut (27.5%) and lowest in Rh. pulchellus (29.4%), where midgut and hemolymph detection rates were 17.6% and 11.8%, respectively. Similarly, in Hy. dromedarii, R. africae was mainly detected in the midgut (41.7%) but was absent in the hemolymph. Rickettsia africae was not detected in Hy. rufipes. No Coxiella, Theileria, or Babesia spp. were detected in this study. Conclusions The tissue-specific localization of R. africae, found mainly in the hemolymph of Am. gemma, is congruent with the role of this tick species as its transmission vector. Thus, occurrence of TBPs in the hemolymph could serve as a predictor of vector competence of TBP transmission, especially in comparison to detection rates in the midgut, from which they must cross tissue barriers to effectively replicate and disseminate across tick tissues. Further studies should focus on exploring the distribution of TBPs within tick tissues to enhance knowledge of TBP epidemiology and to distinguish competent vectors from dead-end hosts.
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Affiliation(s)
- Rua Khogali
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
- Department of Parasitology, Faculty of Veterinary Medicine, University of Khartoum, Khartoum North, Sudan
| | - Armanda Bastos
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
- Department of Veterinary Tropical Diseases, University of Pretoria, Pretoria, South Africa
| | - Joel L. Bargul
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology (JKUAT), Nairobi, Kenya
| | - Dennis Getange
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - James Kabii
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Daniel Masiga
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Jandouwe Villinger
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
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Lilak AA, Pecor DB, Matulis G, Potter AM, Wofford RN, Kearney MF, Mitchell S, Jaradat F, Kano A, Zimmerman DM, Hassell JM, Kumsa B, Kamau M, Linton YM, von Fricken ME. Data release: targeted systematic literature search for tick and tick-borne pathogen distributions in six countries in sub-Saharan Africa from 1901 to 2020. Parasit Vectors 2024; 17:84. [PMID: 38389097 PMCID: PMC10885379 DOI: 10.1186/s13071-023-06086-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 12/07/2023] [Indexed: 02/24/2024] Open
Abstract
BACKGROUND Surveillance data documenting tick and tick-borne disease (TBD) prevalence is needed to develop risk assessments and implement control strategies. Despite extensive research in Africa, there is no standardized, comprehensive review. METHODS Here we tackle this knowledge gap, by producing a comprehensive review of research articles on ticks and TBD between 1901 and 2020 in Chad, Djibouti, Ethiopia, Kenya, Tanzania, and Uganda. Over 8356 English language articles were recovered. Our search strategy included 19 related MeSH terms. Articles were reviewed, and 331 met inclusion criteria. Articles containing mappable data were compiled into a standardized data schema, georeferenced, and uploaded to VectorMap. RESULTS Tick and pathogen matrixes were created, providing information on vector distributions and tick-pathogen associations within the six selected African countries. CONCLUSIONS These results provide a digital, mappable database of current and historical tick and TBD distributions across six countries in Africa, which can inform specific risk modeling, determine surveillance gaps, and guide future surveillance priorities.
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Affiliation(s)
- Abigail A Lilak
- One Health Center of Excellence, Emerging Pathogens Institute, University of Florida, 2055 Mowry Road, Gainesville, FL, 32611, USA
- Department of Environmental & Global Health, University of Florida, Gainesville, FL, USA
| | - David B Pecor
- Walter Reed Biosystematics Unit (WRBU), Smithsonian Museum Support Center, Suitland, MD, USA
- Department of Entomology, Smithsonian Institution-National Museum of Natural History, Washington, DC, USA
- One Health Branch, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA
| | - Graham Matulis
- One Health Center of Excellence, Emerging Pathogens Institute, University of Florida, 2055 Mowry Road, Gainesville, FL, 32611, USA
- Department of Environmental & Global Health, University of Florida, Gainesville, FL, USA
| | - Alexander M Potter
- Walter Reed Biosystematics Unit (WRBU), Smithsonian Museum Support Center, Suitland, MD, USA
- Department of Entomology, Smithsonian Institution-National Museum of Natural History, Washington, DC, USA
- One Health Branch, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA
| | | | | | - Stephanie Mitchell
- Walter Reed Biosystematics Unit (WRBU), Smithsonian Museum Support Center, Suitland, MD, USA
| | | | - Arisa Kano
- George Mason University, Fairfax, VA, USA
| | - Dawn M Zimmerman
- Department of Entomology, Smithsonian Institution-National Museum of Natural History, Washington, DC, USA
- Yale University, New Haven, CT, USA
| | - James M Hassell
- Department of Entomology, Smithsonian Institution-National Museum of Natural History, Washington, DC, USA
- Yale University, New Haven, CT, USA
| | - Bersissa Kumsa
- Department of Pathology & Parasitology, College of Veterinary Medicine and Agriculture, Addis Ababa University, Bishoftu, Ethiopia
| | - Maureen Kamau
- Walter Reed Biosystematics Unit (WRBU), Smithsonian Museum Support Center, Suitland, MD, USA
- Mpala Research Center, Nanyuki, Kenya
| | - Yvonne-Marie Linton
- Walter Reed Biosystematics Unit (WRBU), Smithsonian Museum Support Center, Suitland, MD, USA
- Department of Entomology, Smithsonian Institution-National Museum of Natural History, Washington, DC, USA
- One Health Branch, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA
| | - Michael E von Fricken
- One Health Center of Excellence, Emerging Pathogens Institute, University of Florida, 2055 Mowry Road, Gainesville, FL, 32611, USA.
- Department of Environmental & Global Health, University of Florida, Gainesville, FL, USA.
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Majid A, Almutairi MM, Alouffi A, Tanaka T, Yen TY, Tsai KH, Ali A. First report of spotted fever group Rickettsia aeschlimannii in Hyalomma turanicum, Haemaphysalis bispinosa, and Haemaphysalis montgomeryi infesting domestic animals: updates on the epidemiology of tick-borne Rickettsia aeschlimannii. Front Microbiol 2023; 14:1283814. [PMID: 38163073 PMCID: PMC10756324 DOI: 10.3389/fmicb.2023.1283814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 11/13/2023] [Indexed: 01/03/2024] Open
Abstract
Tick-borne Rickettsia spp. have long been known as causative agents for zoonotic diseases. We have previously characterized Rickettsia spp. in different ticks infesting a broad range of hosts in Pakistan; however, knowledge regarding Rickettsia aeschlimannii in Haemaphysalis and Hyalomma ticks is missing. This study aimed to obtain a better understanding about R. aeschlimannii in Pakistan and update the knowledge about its worldwide epidemiology. Among 369 examined domestic animals, 247 (66%) were infested by 872 ticks. Collected ticks were morphologically delineated into three genera, namely, Rhipicephalus, Hyalomma, and Haemaphysalis. Adult females were the most prevalent (number ₌ 376, 43.1%), followed by nymphs (303, 34.74%) and males (193, 22.13%). Overall, genomic DNA samples of 223 tick were isolated and screened for Rickettsia spp. by the amplification of rickettsial gltA, ompA, and ompB partial genes using conventional PCR. Rickettsial DNA was detected in 8 of 223 (3.58%) ticks including nymphs (5 of 122, 4.0%) and adult females (3 of 86, 3.48%). The rickettsial gltA, ompA, and ompB sequences were detected in Hyalomma turanicum (2 nymphs and 1 adult female), Haemaphysalis bispinosa (1 nymph and 1 adult female), and Haemaphysalis montgomeryi (2 nymphs and 1 adult female). These rickettsial sequences showed 99.71-100% identity with R. aeschlimannii and phylogenetically clustered with the same species. None of the tested Rhipicephalus microplus, Hyalomma isaaci, Hyalomma scupense, Rhipicephalus turanicus, Hyalomma anatolicum, Rhipicephalus haemaphysaloides, Rhipicephalus sanguineus, Haemaphysalis cornupunctata, and Haemaphysalis sulcata ticks were found positive for rickettsial DNA. Comprehensive surveillance studies should be adopted to update the knowledge regarding tick-borne zoonotic Rickettsia species, evaluate their risks to humans and livestock, and investigate the unexamined cases of illness after tick bite among livestock holders in the country.
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Affiliation(s)
- Abdul Majid
- Department of Zoology, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Mashal M. Almutairi
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Abdulaziz Alouffi
- King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
| | - Tetsuya Tanaka
- Laboratory of Infectious Diseases, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
| | - Tsai-Ying Yen
- Department of Public Health, Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Kun-Hsien Tsai
- Department of Public Health, Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Abid Ali
- Department of Zoology, Abdul Wali Khan University Mardan, Mardan, Pakistan
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Onyiche TE, Labruna MB, Saito TB. Unraveling the epidemiological relationship between ticks and rickettsial infection in Africa. FRONTIERS IN TROPICAL DISEASES 2022. [DOI: 10.3389/fitd.2022.952024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tick-borne rickettsioses are emerging and re-emerging diseases of public health concern caused by over 30 species of Rickettsia. Ticks are obligate hematophagous arthropods with over 700 species of Ixodid ticks known worldwide. The escalating geographical dispersal of tick vectors and concomitant increase in the incidences of tick-borne diseases have fueled interest in the ecology of tick-borne pathogens. This review focuses on aspects of the Rickettsia pathogen, including biology, taxonomy, phylogeny, genetic diversity, epidemiology of the disease, and the role of vertebrate host in the perpetuation of rickettsioses in Africa. Our review also highlights some of the species of Rickettsia that are responsible for disease, the role of tick vectors (both hard and soft ticks) and the species of Rickettsia associated with diverse tick species across the continent. Additionally, this article emphasizes the evolutionary perspective of rickettsiae perpetuation and the possible role of amplifying vertebrate host and other small mammals, domestic animals and wildlife in the epidemiology of Rickettsia species. We also specifically, discussed the role of avian population in the epidemiology of SFG rickettsiae. Furthermore, we highlighted tick-borne rickettsioses among travelers due to African tick-bite fever (ATBF) and the challenges to surveillance of rickettsial infection, and research on rickettsiology in Africa. Our review canvasses the need for more rickettsiologists of African origin based within the continent to further research towards understanding the biology, characterization, and species distribution, including the competent tick vectors involved in their transmission of rickettsiae across the continent in collaboration with established researchers in western countries. We further highlighted the need for proper funding to encourage research despite competing demands for resources across the various sectors. We finalize by discussing the similarities between rickettsial diseases around the world and which steps need to be taken to help foster our understanding on the eco-epidemiology of rickettsioses by bridging the gap between the growing epidemiological data and the molecular characterization of Rickettsia species.
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Peter SG, Kariuki HW, Aboge GO, Gakuya DW, Maingi N, Mulei CM. Prevalence of Ticks Infesting Dairy Cattle and the Pathogens They Harbour in Smallholder Farms in Peri-Urban Areas of Nairobi, Kenya. Vet Med Int 2021; 2021:9501648. [PMID: 34925753 PMCID: PMC8683169 DOI: 10.1155/2021/9501648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 11/19/2021] [Indexed: 11/17/2022] Open
Abstract
This study aimed at determining the tick species infesting dairy cattle in Nairobi, Kenya, and the pathogens they harbour. While ticks are well-known vectors of major bacterial pathogens of both veterinary importance and public health importance, few studies have investigated the range of the tick species and the associated pathogens, especially present in unique dairy production systems, which compromise animal welfare, such as those in peri-urban areas. A cross-sectional study was undertaken involving 314 randomly selected dairy cattle in 109 smallholder farms. Each animal was examined for attached ticks followed by morphological tick identification at the species level. Genomic DNA was extracted from each of the ticks, and 16S rDNA gene was amplified for pathogen identification. Sequencing of the amplicons and subsequent BLASTn analysis, multiple sequence alignment, and phylogenetic reconstruction were performed to confirm the species of the pathogens. Sixty-six (21.0%) of the cattle examined had ticks. A total of 94 adult ticks were found on the cattle, and of these, 63 (67.0%), 18 (19.1%), and 13 (13.8%) were in the genera Rhipicephalus, Amblyomma, and Hyalomma, respectively. Twelve tick species in Rhipicephalus genus and two in Amblyomma and Hyalomma genera were identified. Although Rh. decoloratus was the most prevalent tick (24.5% (23/94)), the emerging Rh. microplus (6.4% (6/94)) was also identified. The DNA of Rickettsia was detected in the ticks, with Rickettsia conorii in H. rufipes and A. variegatum, and Rickettsia aeschlimannii in Rh. microplus and H. rufipes, while Ehrlichia ruminantium and E. canis were in A. variegatum. In conclusion, the study reported a wide range of tick species present in the study area including Rhipicephalus microplus, which is an emerging tick species in parts of Kenya. The ticks harboured DNA of Rickettsia and Ehrlichia, highlighting possible animal and human health concerns. Hence, effective tick control strategies remain paramount to prevent potential diseases associated with the harboured pathogens.
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Affiliation(s)
- Shepelo Getrude Peter
- Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, P.O. Box 29053-00625, Nairobi, Kenya
| | - Hellen Wambui Kariuki
- Department of Microbiology, Faculty of Health Sciences, University of Nairobi, P.O. Box 19676-00202, Nairobi, Kenya
| | - Gabriel Oluga Aboge
- Department of Public Health Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Nairobi, P.O. Box 29053-00625, Nairobi, Kenya
| | - Daniel Waweru Gakuya
- Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, P.O. Box 29053-00625, Nairobi, Kenya
| | - Ndichu Maingi
- Department of Veterinary Pathology, Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Nairobi, P.O. Box 29053-00625, Nairobi, Kenya
| | - Charles Matiku Mulei
- Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, P.O. Box 29053-00625, Nairobi, Kenya
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Getange D, Bargul JL, Kanduma E, Collins M, Bodha B, Denge D, Chiuya T, Githaka N, Younan M, Fèvre EM, Bell-Sakyi L, Villinger J. Ticks and Tick-Borne Pathogens Associated with Dromedary Camels ( Camelus dromedarius) in Northern Kenya. Microorganisms 2021; 9:1414. [PMID: 34209060 PMCID: PMC8306667 DOI: 10.3390/microorganisms9071414] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 06/21/2021] [Accepted: 06/22/2021] [Indexed: 12/17/2022] Open
Abstract
Ticks and tick-borne pathogens (TBPs) are major constraints to camel health and production, yet epidemiological data on their diversity and impact on dromedary camels remain limited. We surveyed the diversity of ticks and TBPs associated with camels and co-grazing sheep at 12 sites in Marsabit County, northern Kenya. We screened blood and ticks (858 pools) from 296 camels and 77 sheep for bacterial and protozoan TBPs by high-resolution melting analysis and sequencing of PCR products. Hyalomma (75.7%), Amblyomma (17.6%) and Rhipicephalus (6.7%) spp. ticks were morphologically identified and confirmed by molecular analyses. We detected TBP DNA in 80.1% of blood samples from 296 healthy camels. "Candidatus Anaplasma camelii", "Candidatus Ehrlichia regneryi" and Coxiella burnetii were detected in both camels and associated ticks, and Ehrlichia chaffeensis, Rickettsia africae, Rickettsia aeschlimannii and Coxiella endosymbionts were detected in camel ticks. We also detected Ehrlichia ruminantium, which is responsible for heartwater disease in ruminants, in Amblyomma ticks infesting camels and sheep and in sheep blood, indicating its endemicity in Marsabit. Our findings also suggest that camels and/or the ticks infesting them are disease reservoirs of zoonotic Q fever (C. burnetii), ehrlichiosis (E. chaffeensis) and rickettsiosis (R. africae), which pose public health threats to pastoralist communities.
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Affiliation(s)
- Dennis Getange
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (D.G.); (T.C.)
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi P.O. Box 62000-00200, Kenya
| | - Joel L. Bargul
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (D.G.); (T.C.)
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi P.O. Box 62000-00200, Kenya
| | - Esther Kanduma
- Department of Biochemistry, School of Medicine, University of Nairobi, Nairobi P.O. Box 30197-00100, Kenya;
| | - Marisol Collins
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (E.M.F.); (L.B.-S.)
| | - Boku Bodha
- Directorate of Veterinary Services, County Government of Marsabit, Marsabit P.O. Box 384-60500, Kenya; (B.B.); (D.D.)
| | - Diba Denge
- Directorate of Veterinary Services, County Government of Marsabit, Marsabit P.O. Box 384-60500, Kenya; (B.B.); (D.D.)
| | - Tatenda Chiuya
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (D.G.); (T.C.)
| | - Naftaly Githaka
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya;
| | - Mario Younan
- Food and Agriculture Organization of the United Nations (FAO), Programme & Operational Support to Syria Crisis, UN cross-border hub, Gaziantep 27010, Turkey;
| | - Eric M. Fèvre
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (E.M.F.); (L.B.-S.)
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya;
| | - Lesley Bell-Sakyi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (E.M.F.); (L.B.-S.)
| | - Jandouwe Villinger
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (D.G.); (T.C.)
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8
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Chiuya T, Masiga DK, Falzon LC, Bastos ADS, Fèvre EM, Villinger J. Tick-borne pathogens, including Crimean-Congo haemorrhagic fever virus, at livestock markets and slaughterhouses in western Kenya. Transbound Emerg Dis 2020; 68:2429-2445. [PMID: 33142046 PMCID: PMC8359211 DOI: 10.1111/tbed.13911] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/26/2020] [Accepted: 10/31/2020] [Indexed: 12/14/2022]
Abstract
Vectors of emerging infectious diseases have expanded their distributional ranges in recent decades due to increased global travel, trade connectivity and climate change. Transboundary range shifts, arising from the continuous movement of humans and livestock across borders, are of particular disease control concern. Several tick-borne diseases are known to circulate between eastern Uganda and the western counties of Kenya, with one fatal case of Crimean-Congo haemorrhagic fever (CCHF) reported in 2000 in western Kenya. Recent reports of CCHF in Uganda have highlighted the risk of cross-border disease translocation and the importance of establishing inter-epidemic, early warning systems to detect possible outbreaks. We therefore carried out surveillance of tick-borne zoonotic pathogens at livestock markets and slaughterhouses in three counties of western Kenya that neighbour Uganda. Ticks and other ectoparasites were collected from livestock and identified using morphological keys. The two most frequently sampled tick species were Rhipicephalus decoloratus (35%) and Amblyomma variegatum (30%); Ctenocephalides felis fleas and Haematopinus suis lice were also present. In total, 486 ticks, lice and fleas were screened for pathogen presence using established molecular workflows incorporating high-resolution melting analysis and identified through sequencing of PCR products. We detected CCHF virus in Rh. decoloratus and Rhipicephalus sp. cattle ticks, and 82 of 96 pools of Am. variegatum were positive for Rickettsia africae. Apicomplexan protozoa and bacteria of veterinary importance, such as Theileria parva, Babesia bigemina and Anaplasma marginale, were primarily detected in rhipicephaline ticks. Our findings show the presence of several pathogens of public health and veterinary importance in ticks from livestock at livestock markets and slaughterhouses in western Kenya. Confirmation of CCHF virus, a Nairovirus that causes haemorrhagic fever with a high case fatality rate in humans, highlights the risk of under-diagnosed zoonotic diseases and calls for continuous surveillance and the development of preventative measures.
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Affiliation(s)
- Tatenda Chiuya
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya.,Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Daniel K Masiga
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Laura C Falzon
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Neston, UK.,International Livestock Research Institute, Nairobi, Kenya
| | - Armanda D S Bastos
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Eric M Fèvre
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Neston, UK.,International Livestock Research Institute, Nairobi, Kenya
| | - Jandouwe Villinger
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
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Oundo JW, Villinger J, Jeneby M, Ong’amo G, Otiende MY, Makhulu EE, Musa AA, Ouso DO, Wambua L. Pathogens, endosymbionts, and blood-meal sources of host-seeking ticks in the fast-changing Maasai Mara wildlife ecosystem. PLoS One 2020; 15:e0228366. [PMID: 32866142 PMCID: PMC7458302 DOI: 10.1371/journal.pone.0228366] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 07/27/2020] [Indexed: 01/07/2023] Open
Abstract
The role of questing ticks in the epidemiology of tick-borne diseases in Kenya's Maasai Mara National Reserve (MMNR), an ecosystem with intensified human-wildlife-livestock interactions, remains poorly understood. We surveyed the diversity of questing ticks, their blood-meal hosts, and tick-borne pathogens to understand potential effects on human and livestock health. By flagging and hand-picking from vegetation in 25 localities, we collected 1,465 host-seeking ticks, mostly Rhipicephalus and Amblyomma species identified by morphology and molecular analysis. We used PCR with high-resolution melting (HRM) analysis and sequencing to identify Anaplasma, Babesia, Coxiella, Ehrlichia, Rickettsia, and Theileria pathogens and blood-meal remnants in 231 tick pools. We detected blood-meals from humans, wildebeest, and African buffalo in Rh. appendiculatus, goat in Rh. evertsi, sheep in Am. gemma, and cattle in Am. variegatum. Rickettsia africae was detected in Am. gemma (MIR = 3.10) that had fed on sheep and in Am. variegatum (MIR = 250) that had fed on cattle. We found Rickettsia spp. in Am. gemma (MIR = 9.29) and Rh. evertsi (MIR = 200), Anaplasma ovis in Rh. appendiculatus (MIR = 0.89) and Rh. evertsi (MIR = 200), Anaplasma bovis in Rh. appendiculatus (MIR = 0.89), and Theileria parva in Rh. appendiculatus (MIR = 24). No Babesia, Ehrlichia, or Coxiella pathogens were detected. Unexpectedly, species-specific Coxiella sp. endosymbionts were detected in all tick genera (174/231 pools), which may affect tick physiology and vector competence. These findings show that ticks from the MMNR are infected with zoonotic R. africae and unclassified Rickettsia spp., demonstrating risk of African tick-bite fever and other spotted-fever group rickettsioses to locals and visitors. The protozoan pathogens identified may also pose risk to livestock production. The diverse vertebrate blood-meals of questing ticks in this ecosystem including humans, wildlife, and domestic animals, may amplify transmission of tick-borne zoonoses and livestock diseases.
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Affiliation(s)
- Joseph Wang’ang’a Oundo
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Jandouwe Villinger
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Maamun Jeneby
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Institute of Primate Research, National Museums of Kenya, Nairobi, Kenya
| | - George Ong’amo
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | | | - Edward Edmond Makhulu
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Biochemistry and Molecular Biology, Egerton University, Egerton, Kenya
| | - Ali Abdulahi Musa
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Medical Laboratory Sciences, Kenyatta University, Nairobi, Kenya
| | - Daniel Obado Ouso
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Lillian Wambua
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
- * E-mail:
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Hughes EC, Anderson NE. Zoonotic Pathogens of Dromedary Camels in Kenya: A Systematised Review. Vet Sci 2020; 7:vetsci7030103. [PMID: 32764264 PMCID: PMC7559378 DOI: 10.3390/vetsci7030103] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/21/2020] [Accepted: 07/01/2020] [Indexed: 01/26/2023] Open
Abstract
Kenya is home to Africa’s third largest population of dromedary camels, and production at commercial and local levels are increasingly important. In pastoral and nomadic communities in the arid and semi-arid lands (ASALs), camels play a vital role in food security, while commercial milk production and formalized export markets are rapidly emerging as camel populations expand into non-traditional areas. Until recently, little focus was placed on camels as hosts of zoonotic disease, but the emergence of Middle Eastern respiratory coronavirus (MERS-CoV) in 2012, and the discovery of exposure to the virus in Kenyan camels, highlighted the need for further understanding of this area. This systematised review utilised a robust search strategy to assess the occurrence of camel-associated zoonoses in Kenya and to evaluate the quality of the published literature. Seventy-four studies were identified, covering sixteen pathogens, with an increasing number of good quality studies in recent years. Despite this, the area remains under-researched and there is a lack of robust, high-quality research. Trypanosome spp., Echinococcus granulosus and Brucella spp. appeared most frequently in the literature. Pathogens with the highest reported prevalence were MERS-CoV (0–100%), Echinococcus granulosa (7–60%) and Rift Valley fever virus (7–57%). Exposure to Brucella spp., Coxiella burnetii and Crimean-Congo haemorrhagic fever virus showed higher levels in camel or camel-associated vectors than other livestock species, although brucellosis was the only disease for which there was robust evidence linking camel and human exposure. Zoonotic agents with less severe human health outcomes, such as Dermatophilosus congolensis and contagious ecthyma, were also represented in the literature. This review provides an important summary of the scope and quality of current knowledge. It demonstrates that further research, and improved adherence to robust study design and reporting are essential if the zoonotic risk from camels in Kenya, and elsewhere, is to be better understood.
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Affiliation(s)
- Ellen Clare Hughes
- The Royal (Dick) School of Veterinary Studies and the Roslin Institute, University of Edinburgh, Roslin EH25 9RG, UK;
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Henry Wellcome Building, Garscube Campus, Glasgow G61 1QH, UK
- Correspondence:
| | - Neil Euan Anderson
- The Royal (Dick) School of Veterinary Studies and the Roslin Institute, University of Edinburgh, Roslin EH25 9RG, UK;
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Vector-borne bacteria in blood of camels in Iran: New data and literature review. Comp Immunol Microbiol Infect Dis 2019; 65:48-53. [PMID: 31300125 PMCID: PMC7112553 DOI: 10.1016/j.cimid.2019.04.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 04/05/2019] [Accepted: 04/08/2019] [Indexed: 12/27/2022]
Abstract
Information about vector-borne bacteria of camels is scarce. Anaplasmataceae, SFG rickettsiae, Bartonella and Borrelia were investigated in blood of 200 dromedary camels of Iran. PCR results revealed 30 animals (15%) to be infected with Anaplasmataceae bacteria. BlastN® analysis of positive samples revealed identity with “Candidatus Anaplasma camelii” isolates. This paper reviews the current knowledge on camels’ tick-borne bacteria including microscopy, serology and molecular studies.
Despite close association between camels and humans, molecular based studies on vector-borne pathogens infecting camels are scarce compared to other animals in Iran. The current study was carried out to investigate the occurrence of vector-borne bacteria in the blood of dromedaries by molecular tools. A total of 200 peripheral blood samples were collected from apparently healthy animals. Microscopic examination was performed on Giemsa-stained blood smears, and drops of blood were spotted on Whatman FTA® cards for molecular analyses. Genomic DNA was extracted from the cards, and PCR amplification followed by sequencing of positive samples was carried out for the detection of Anaplasmataceae, spotted fever group (SFG) rickettsiae, Bartonella spp. and Borrelia spp. Intra-cytic forms of any blood pathogens could not be detected by light microscopy. PCR results revealed 30 animals (15%) to be infected with Anaplasmataceae bacteria. Analyses of sequences revealed a strain of Anaplasma sp. identical to Candidatus Anaplasma camelii isolated from camels, cattle and deer in Asia and Africa. Neither SFG rickettsiae, nor Borrelia or Bartonella species were found. Further studies for determining epidemiological role of camels and its zoonotic potential are recommended. This paper reviews the current knowledge on camels’ tickborne bacteria including microscopy, serology and molecular studies.
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Koka H, Sang R, Kutima HL, Musila L. Coxiella burnetii Detected in Tick Samples from Pastoral Communities in Kenya. BIOMED RESEARCH INTERNATIONAL 2018; 2018:8158102. [PMID: 30105251 PMCID: PMC6076967 DOI: 10.1155/2018/8158102] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/23/2018] [Accepted: 06/05/2018] [Indexed: 01/05/2023]
Abstract
Ticks are important disease vectors in Kenya with documented evidence of carriage of zoonotic pathogens. Coxiella burnetii is an important tick-borne pathogen that is underreported in Kenya and yet this infection likely contributes to undiagnosed febrile disease in pastoral communities. Archived human blood (278) and tick pool samples (380) collected from five pastoral communities in Kenya were screened for C. burnetii by PCR using primers targeting the transposon-like IS1111 region. All the human blood samples were negative for C. burnetii DNA. However, C. burnetii was detected in 5.53% (21/380) of the tick pools tested. Four of the twenty-one PCR positive samples were sequenced. The findings indicate that Coxiella burnetii was not present in the human blood samples tested. However, C. burnetii was detected in ticks from Mai Mahiu, Marigat, Ijara, Isiolo, and Garissa indicating a natural infection present in the tick vector that poses a risk to livestock and humans in these communities.
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Affiliation(s)
- Hellen Koka
- Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya
- US Army Medical Research Directorate-Kenya, P.O. Box 606-00621, Nairobi, Kenya
| | - Rosemary Sang
- Kenya Medical Research Institute, Centre for Virus Research, P.O. Box 54628-00200, Nairobi, Kenya
- International Centre for Insect Physiology and Ecology, P.O. Box 30772-00100, Kenya
| | - Helen Lydia Kutima
- Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya
| | - Lillian Musila
- US Army Medical Research Directorate-Kenya, P.O. Box 606-00621, Nairobi, Kenya
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