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Fracasso G, Heylen D, Van Dongen S, Elst J, Matthysen E. Predictors of individual performance and evolutionary potential of life-history traits in a hematophagous ectoparasite. Evolution 2022; 76:799-816. [PMID: 35238032 PMCID: PMC9314103 DOI: 10.1111/evo.14463] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 11/12/2021] [Accepted: 01/07/2022] [Indexed: 01/22/2023]
Abstract
Little is known about the intraspecific variation of parasite life-history traits and how this variation may affect parasite fitness and evolution. We investigated how life-history traits predict success of individual tree-hole ticks Ixodes arboricola and estimated their evolutionary potential, as well as genetic correlations within stages and phenotypic correlations within and across stages. Ticks were followed individually over two generations while allowed to feed on great tits Parus major. After accounting for host and tick maternal effects, we found that short feeding times and high engorgement weights strongly increased molting success. Molting time was also positively correlated with feeding success in adults. In larvae and nymphs, we found negative phenotypic correlations between engorgement weight and both feeding and molting time, the latter supported by a negative genetic correlation. We found sex-related differences in feeding time (longer in male nymphs) and molting time (longer in male larvae but shorter in male nymphs). Also, time since the last feeding event (set experimentally) reduced larval and nymphal fitness, whereas it increased adult female fitness. Furthermore, we found significant heritability and evolvability, that is, the potential to respond to selection, for engorgement weight and molting time across all stages but no significant heritability for feeding time. Our findings suggest that variation in tick fitness is shaped by consistent individual differences in tick quality, for which engorgement weight is a good proxy, rather than by life-history trade-offs.
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Affiliation(s)
- Gerardo Fracasso
- Evolutionary Ecology Group, Department of BiologyUniversity of AntwerpWilrijkB‐2610Belgium
| | - Dieter Heylen
- Interuniversity Institute for Biostatistics and statistical BioinformaticsHasselt UniversityDiepenbeekB‐3590Belgium
- Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonNew Jersey08544
- Eco‐Epidemiology Group, Department of Biomedical SciencesInstitute of Tropical MedicineAntwerpB‐2000Belgium
| | - Stefan Van Dongen
- Evolutionary Ecology Group, Department of BiologyUniversity of AntwerpWilrijkB‐2610Belgium
| | - Joris Elst
- Evolutionary Ecology Group, Department of BiologyUniversity of AntwerpWilrijkB‐2610Belgium
| | - Erik Matthysen
- Evolutionary Ecology Group, Department of BiologyUniversity of AntwerpWilrijkB‐2610Belgium
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Mawela KG, Luseba D, Magano S, Eloff JN. Repellent properties of Rotheca glabrum plant extracts against adults of Rhipicephalus appendiculatus. BMC Vet Res 2019; 15:122. [PMID: 31029169 PMCID: PMC6487012 DOI: 10.1186/s12917-019-1853-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 03/26/2019] [Indexed: 12/19/2022] Open
Abstract
Background Rotheca glabrum (formerly known as Clerodendrum glabrum [Verbenaceae]) is used by local communities in the Limpopo Province of South Africa to control ticks on livestock and was selected from the database of the ARC-Onderstepoort Veterinary Institute. Its leaves were extracted using organic solvents ranging from polar to non-polar solvents (methanol, acetone and dichloromethane (DCM)). In addition, the traditional soap-water (infusion) and water-based (decoction) methods were used. The tick repelling activity was determined against the adult stage of the livestock tick Rhipicephalus appendiculatus. Results In the tick-climbing repellency bioassay a 30% acetone extract had a significant (p ≤ 0.05) repellent effect against adults of R. appendiculatus. The extract was still active at a lower concentration of 10%. The hexane fraction from the R. glabrum acetone extract had a higher tick repellency activity than the positive controls Amitix and Bayticol at the same concentrations. Unfortunately, the activity decreased after 2.5 h, probably due to volatility of the biologically active compound(s) within the extract. Conclusion Attempts were made to isolate the repellent compound from the acetone extract of R. glabrum. The process produced very good results up to a late stage in the bioassay-guided fractionation process. At that point, the repellent activity was lost. When two fractions were combined, the repellent activity was regained. These results provide strong evidence for the existence of a synergisticactivity of different compounds. It may be better to concentrate on extracts that would kill ticks rather than on extracts that would repel ticks.
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Affiliation(s)
- Kedibone Gloria Mawela
- Phytomedicine Programme, Department of Paraclinical Sciences, University of Pretoria, Private Bag X04, Onderstepoort, 0110, Republic of South Africa.,Agricultural Research Council, Onderstepoort Veterinary Research, Division of Toxicology, Private Bag X05, Onderstepoort, 0110, South Africa
| | - Dibungi Luseba
- Department of Animal Sciences, Faculty of Science, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa
| | - Solomon Magano
- Department of Life and Consumer Science, University of South Africa, Private Bag X6, Florida, 1710, Republic of South Africa
| | - Jacobus Nicolaas Eloff
- Department Agriculture and Animal Health, University of South Africa, Private Bag X6, Florida, 1710, Republic of South Africa.
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Amzati GS, Pelle R, Muhigwa JBB, Kanduma EG, Djikeng A, Madder M, Kirschvink N, Marcotty T. Mitochondrial phylogeography and population structure of the cattle tick Rhipicephalus appendiculatus in the African Great Lakes region. Parasit Vectors 2018; 11:329. [PMID: 29855375 PMCID: PMC5984310 DOI: 10.1186/s13071-018-2904-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 05/16/2018] [Indexed: 12/02/2022] Open
Abstract
Background The ixodid tick Rhipicephalus appendiculatus is the main vector of Theileria parva, wich causes the highly fatal cattle disease East Coast fever (ECF) in sub-Saharan Africa. Rhipicephalus appendiculatus populations differ in their ecology, diapause behaviour and vector competence. Thus, their expansion in new areas may change the genetic structure and consequently affect the vector-pathogen system and disease outcomes. In this study we investigated the genetic distribution of R. appendiculatus across agro-ecological zones (AEZs) in the African Great Lakes region to better understand the epidemiology of ECF and elucidate R. appendiculatus evolutionary history and biogeographical colonization in Africa. Methods Sequencing was performed on two mitochondrial genes (cox1 and 12S rRNA) of 218 ticks collected from cattle across six AEZs along an altitudinal gradient in the Democratic Republic of Congo, Rwanda, Burundi and Tanzania. Phylogenetic relationships between tick populations were determined and evolutionary population dynamics models were assessed by mismach distribution. Results Population genetic analysis yielded 22 cox1 and 9 12S haplotypes in a total of 209 and 126 nucleotide sequences, respectively. Phylogenetic algorithms grouped these haplotypes for both genes into two major clades (lineages A and B). We observed significant genetic variation segregating the two lineages and low structure among populations with high degree of migration. The observed high gene flow indicates population admixture between AEZs. However, reduced number of migrants was observed between lowlands and highlands. Mismatch analysis detected a signature of rapid demographic and range expansion of lineage A. The star-like pattern of isolated and published haplotypes indicates that the two lineages evolve independently and have been subjected to expansion across Africa. Conclusions Two sympatric R. appendiculatus lineages occur in the Great Lakes region. Lineage A, the most diverse and ubiquitous, has experienced rapid population growth and range expansion in all AEZs probably through cattle movement, whereas lineage B, the less abundant, has probably established a founder population from recent colonization events and its occurrence decreases with altitude. These two lineages are sympatric in central and eastern Africa and allopatric in southern Africa. The observed colonization pattern may strongly affect the transmission system and may explain ECF endemic instability in the tick distribution fringes. Electronic supplementary material The online version of this article (10.1186/s13071-018-2904-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gaston S Amzati
- Unit of Integrated Veterinary Research, Department of Veterinary Medicine, Faculty of Sciences, Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), Rue de Bruxelles 61, 5000, Namur, Belgium. .,Research Unit of Veterinary Epidemiology and Biostatistics, Faculty of Agricultural and Environmental Sciences, Université Evangélique en Afrique, P.O. Box 3323, Bukavu, Democratic Republic of the Congo. .,Biosciences eastern and central Africa - International Livestock Research Institute (BecA-ILRI) hub, P.O. Box 30709-00100, Nairobi, Kenya.
| | - Roger Pelle
- Biosciences eastern and central Africa - International Livestock Research Institute (BecA-ILRI) hub, P.O. Box 30709-00100, Nairobi, Kenya
| | - Jean-Berckmans B Muhigwa
- Research Unit of Veterinary Epidemiology and Biostatistics, Faculty of Agricultural and Environmental Sciences, Université Evangélique en Afrique, P.O. Box 3323, Bukavu, Democratic Republic of the Congo
| | - Esther G Kanduma
- Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
| | - Appolinaire Djikeng
- Biosciences eastern and central Africa - International Livestock Research Institute (BecA-ILRI) hub, P.O. Box 30709-00100, Nairobi, Kenya.,Present address: Centre for Tropical Livestock Genetics and Health (CTLGH), The University of Edinburgh, Easter Bush, Midlothian, Scotland, EH25 9RG, UK
| | - Maxime Madder
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, P/Bag X04, Onderstepoort, 0110, South Africa
| | - Nathalie Kirschvink
- Unit of Integrated Veterinary Research, Department of Veterinary Medicine, Faculty of Sciences, Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), Rue de Bruxelles 61, 5000, Namur, Belgium
| | - Tanguy Marcotty
- Unit of Integrated Veterinary Research, Department of Veterinary Medicine, Faculty of Sciences, Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), Rue de Bruxelles 61, 5000, Namur, Belgium
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Olds CL, Mwaura S, Odongo DO, Scoles GA, Bishop R, Daubenberger C. Induction of humoral immune response to multiple recombinant Rhipicephalus appendiculatus antigens and their effect on tick feeding success and pathogen transmission. Parasit Vectors 2016; 9:484. [PMID: 27589998 PMCID: PMC5010713 DOI: 10.1186/s13071-016-1774-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Accepted: 08/25/2016] [Indexed: 11/22/2022] Open
Abstract
Background Rhipicephalus appendiculatus is the primary vector of Theileria parva, the etiological agent of East Coast fever (ECF), a devastating disease of cattle in sub-Saharan Africa. We hypothesized that a vaccine targeting tick proteins that are involved in attachment and feeding might affect feeding success and possibly reduce tick-borne transmission of T. parva. Here we report the evaluation of a multivalent vaccine cocktail of tick antigens for their ability to reduce R. appendiculatus feeding success and possibly reduce tick-transmission of T. parva in a natural host-tick-parasite challenge model. Methods Cattle were inoculated with a multivalent antigen cocktail containing recombinant tick protective antigen subolesin as well as two additional R. appendiculatus saliva antigens: the cement protein TRP64, and three different histamine binding proteins. The cocktail also contained the T. parva sporozoite antigen p67C. The effect of vaccination on the feeding success of nymphal and adult R. appendiculatus ticks was evaluated together with the effect on transmission of T. parva using a tick challenge model. Results To our knowledge, this is the first evaluation of the anti-tick effects of these antigens in the natural host-tick-parasite combination. In spite of evidence of strong immune responses to all of the antigens in the cocktail, vaccination with this combination of tick and parasite antigens did not appear to effect tick feeding success or reduce transmission of T. parva. Conclusion The results of this study highlight the importance of early evaluation of anti-tick vaccine candidates in biologically relevant challenge systems using the natural tick-host-parasite combination. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1774-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Cassandra L Olds
- International Livestock Research Institute, Box 30709, Nairobi, 00100, Kenya. .,Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland. .,University of Basel, Petersplatz 1, CH-4003, Basel, Switzerland.
| | - Stephen Mwaura
- International Livestock Research Institute, Box 30709, Nairobi, 00100, Kenya
| | - David O Odongo
- International Livestock Research Institute, Box 30709, Nairobi, 00100, Kenya.,School of Biological Sciences, University of Nairobi, P.O Box 30197, G.P.O, Nairobi, Kenya
| | - Glen A Scoles
- USDA Agricultural Research Service, Animal Disease Research Unit, Pullman, WA, 99164-6630, USA
| | - Richard Bishop
- International Livestock Research Institute, Box 30709, Nairobi, 00100, Kenya
| | - Claudia Daubenberger
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland.,University of Basel, Petersplatz 1, CH-4003, Basel, Switzerland
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Kanduma EG, Mwacharo JM, Githaka NW, Kinyanjui PW, Njuguna JN, Kamau LM, Kariuki E, Mwaura S, Skilton RA, Bishop RP. Analyses of mitochondrial genes reveal two sympatric but genetically divergent lineages of Rhipicephalus appendiculatus in Kenya. Parasit Vectors 2016; 9:353. [PMID: 27334334 PMCID: PMC4918217 DOI: 10.1186/s13071-016-1631-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 06/07/2016] [Indexed: 11/10/2022] Open
Abstract
Background The ixodid tick Rhipicephalus appendiculatus transmits the apicomplexan protozoan parasite Theileria parva, which causes East coast fever (ECF), the most economically important cattle disease in eastern and southern Africa. Recent analysis of micro- and minisatellite markers showed an absence of geographical and host-associated genetic sub-structuring amongst field populations of R. appendiculatus in Kenya. To assess further the phylogenetic relationships between field and laboratory R. appendiculatus tick isolates, this study examined sequence variations at two mitochondrial genes, cytochrome c oxidase subunit I (COI) and 12S ribosomal RNA (rRNA), and the nuclear encoded ribosomal internal transcribed spacer 2 (ITS2) of the rRNA gene, respectively. Results The analysis of 332 COI sequences revealed 30 polymorphic sites, which defined 28 haplotypes that were separated into two distinct haplogroups (A and B). Inclusion of previously published haplotypes in our analysis revealed a high degree of phylogenetic complexity never reported before in haplogroup A. Neither haplogroup however, showed any clustering pattern related to either the geographical sampling location, the type of tick sampled (laboratory stocks vs field populations) or the mammalian host species. This finding was supported by the results obtained from the analysis of 12S rDNA sequences. Analysis of molecular variance (AMOVA) indicated that 90.8 % of the total genetic variation was explained by the two haplogroups, providing further support for their genetic divergence. These results were, however, not replicated by the nuclear transcribed ITS2 sequences likely because of recombination between the nuclear genomes maintaining a high level of genetic sequence conservation. Conclusions COI and 12S rDNA are better markers than ITS2 for studying intraspecific diversity. Based on these genes, two major genetic groups of R. appendiculatus that have gone through a demographic expansion exist in Kenya. The two groups show no phylogeographic structure or correlation with the type of host species from which the ticks were collected, nor to the evolutionary and breeding history of the species. The two lineages may have a wide geographic distribution range in eastern and southern Africa. The findings of this study may have implications for the spread and control of R. appendiculatus, and indirectly, on the transmission dynamics of ECF. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1631-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Esther G Kanduma
- Biosciences eastern and central Africa - International Livestock Research Institute (BecA-ILRI) Hub, P.O. Box 30709-00100, Nairobi, Kenya. .,Present Address: Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya.
| | - Joram M Mwacharo
- Centre for Genetics and Genomics, School of Life Sciences, University Park, University of Nottingham, Nottingham, NG7 2RD, UK.,International Centre for Agricultural Research in the Dry Areas (ICARDA), P.O. Box 5689, Addis Ababa, Ethiopia
| | - Naftaly W Githaka
- International Livestock Research Institute (ILRI), P.O. Box 30709-00100, Nairobi, Kenya
| | - Peter W Kinyanjui
- Present Address: Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
| | - Joyce N Njuguna
- Biosciences eastern and central Africa - International Livestock Research Institute (BecA-ILRI) Hub, P.O. Box 30709-00100, Nairobi, Kenya
| | - Lucy M Kamau
- Department of Zoological Sciences, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya
| | - Edward Kariuki
- Kenya Wildlife Service (KWS), P.O. Box 40241-00100, Nairobi, Kenya
| | - Stephen Mwaura
- International Livestock Research Institute (ILRI), P.O. Box 30709-00100, Nairobi, Kenya
| | - Robert A Skilton
- Biosciences eastern and central Africa - International Livestock Research Institute (BecA-ILRI) Hub, P.O. Box 30709-00100, Nairobi, Kenya.,Present Address: International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya
| | - Richard P Bishop
- International Livestock Research Institute (ILRI), P.O. Box 30709-00100, Nairobi, Kenya
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Kanduma EG, Mwacharo JM, Mwaura S, Njuguna JN, Nzuki I, Kinyanjui PW, Githaka N, Heyne H, Hanotte O, Skilton RA, Bishop RP. Multi-locus genotyping reveals absence of genetic structure in field populations of the brown ear tick (Rhipicephalus appendiculatus) in Kenya. Ticks Tick Borne Dis 2015; 7:26-35. [PMID: 26278352 DOI: 10.1016/j.ttbdis.2015.08.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 07/31/2015] [Accepted: 08/03/2015] [Indexed: 10/23/2022]
Abstract
Rhipicephalus appendiculatus is an important tick vector of several pathogens and parasitizes domestic and wild animals across eastern and southern Africa. However, its inherent genetic variation and population structure is poorly understood. To investigate whether mammalian host species, geographic separation and resulting reproductive isolation, or a combination of these, define the genetic structure of R. appendiculatus, we analyzed multi-locus genotype data from 392 individuals from 10 geographic locations in Kenya generated in an earlier study. These ticks were associated with three types of mammalian host situations; (1) cattle grazing systems, (2) cattle and wildlife co-grazing systems (3) wildlife grazing systems without livestock. We also analyzed data from 460 individuals from 10 populations maintained as closed laboratory stocks and 117 individuals from five other species in the genus Rhipicephalus. The pattern of genotypes observed indicated low levels of genetic differentiation between the ten field populations (FST=0.014±0.002) and a lack of genetic divergence corresponding to the degree of separation of the geographic sampling locations. There was also no clear association of particular tick genotypes with specific host species. This is consistent with tick dispersal over large geographic ranges and lack of host specificity. In contrast, the 10 laboratory populations (FST=0.248±0.015) and the five other species of Rhipicephalus (FST=0.368±0.032) were strongly differentiated into distinct genetic groups. Some laboratory bred populations diverged markedly from their field counterparts in spite of originally being sampled from the same geographic locations. Our results demonstrate a lack of defined population genetic differentiation in field populations of the generalist R. appendiculatus in Kenya, which may be a result of the frequent anthropogenic movement of livestock and mobility of its several wildlife hosts between different locations.
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Affiliation(s)
- Esther G Kanduma
- Biosciences eastern and central Africa - International Livestock Research Institute (BecA-ILRI) Hub, P.O. Box 30709, 00100 Nairobi, Kenya; Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197, Nairobi, Kenya.
| | - Joram M Mwacharo
- Centre for Genetics and Genomics, School of Life Sciences, University Park, University of Nottingham, Nottingham NG7 2RD, UK; International Centre for Agricultural Research in Dry Areas (ICARDA), P.O. Box 5689, Addis Ababa, Ethiopia
| | - Stephen Mwaura
- International Livestock Research Institute (ILRI), P. O. Box 30709, 00100 Nairobi, Kenya
| | - Joyce N Njuguna
- Biosciences eastern and central Africa - International Livestock Research Institute (BecA-ILRI) Hub, P.O. Box 30709, 00100 Nairobi, Kenya
| | - Inosters Nzuki
- Biosciences eastern and central Africa - International Livestock Research Institute (BecA-ILRI) Hub, P.O. Box 30709, 00100 Nairobi, Kenya
| | - Peter W Kinyanjui
- Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197, Nairobi, Kenya
| | - Naftaly Githaka
- International Livestock Research Institute (ILRI), P. O. Box 30709, 00100 Nairobi, Kenya
| | - Heloise Heyne
- Parasites, Vectors, & Vector-Borne Diseases Progamme, ARC-Onderstepoort Veterinary Institute, Pretoria, South Africa
| | - Olivier Hanotte
- Centre for Genetics and Genomics, School of Life Sciences, University Park, University of Nottingham, Nottingham NG7 2RD, UK
| | - Robert A Skilton
- Biosciences eastern and central Africa - International Livestock Research Institute (BecA-ILRI) Hub, P.O. Box 30709, 00100 Nairobi, Kenya
| | - Richard P Bishop
- International Livestock Research Institute (ILRI), P. O. Box 30709, 00100 Nairobi, Kenya
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Odongo DO, Ueti MW, Mwaura SN, Knowles DP, Bishop RP, Scoles GA. Quantification of Theileria parva in Rhipicephalus appendiculatus (Acari: Ixodidae) confirms differences in infection between selected tick strains. JOURNAL OF MEDICAL ENTOMOLOGY 2009; 46:888-894. [PMID: 19645294 DOI: 10.1603/033.046.0422] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Theileria parva is the etiologic agent of East Coast fever, an economically important disease of cattle in sub-Saharan Africa. This protozoan parasite is biologically transmitted by Rhipicephalus appendiculatus (Neumann) (Acari: Ixodidae). An understanding of the vector-parasite interaction may aid the development of improved methods for controlling transmission. We developed quantitative polymerase chain reaction (qPCR) and nested PCR (nPCR) assays targeting the T. parva-specific p104 gene to study T. parva pathogenesis in two strains of R. appendiculatus that had previously been selected to be relatively more (Kiambu) or less (Muguga) susceptible to infection. Nymphs from both strains were fed simultaneously to repletion on acutely infected calves. Nymphs from the Kiambu strain showed significantly higher engorgement weights compared with Muguga strain nymphs. Immediately after engorgement qPCR confirmed that nymphal Kiambu ticks had significantly higher parasite loads at repletion than Muguga nymphs. By 12 d postengorgement, parasites were below quantifiable levels but could be detected by nPCR in 83-87% (Muguga and Kiambu, respectively) of nymphs. After the molt, adult feeding on naïve cattle stimulated parasite replication in the salivary glands. PCR detected significantly more infected ticks than microscopy, and there was a significant difference between the two tick strains both in the proportion of ticks that develop salivary gland infections, and in the number of parasites within infected salivary glands. These data confirm that although both tick strains were competent vectors, Kiambu is both a significantly more susceptible and a more efficient host for T. parva than Muguga. The mechanisms that contribute to the levels of susceptibility and efficiency are unknown; however, this study lays the groundwork for a comparison of the transcriptome of these tick strains, the next step toward discovering the genes involved in the tick-parasite interaction.
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Affiliation(s)
- David O Odongo
- International Livestock Research Institute, P.O. Box 30709, Nairobi, Kenya
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Bishop R, Musoke A, Morzaria S, Gardner M, Nene V. Theileria: intracellular protozoan parasites of wild and domestic ruminants transmitted by ixodid ticks. Parasitology 2006; 129 Suppl:S271-83. [PMID: 15938515 DOI: 10.1017/s0031182003004748] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Theileria are economically important, intra-cellular protozoa, transmitted by ixodid ticks, which infect wild and domestic ruminants. In the mammalian host, parasites infect leukocytes and erythrocytes. In the arthropod vector they develop in gut epithelial cells and salivary glands. All four intra-cellular stages of Theileria survive free in the cytoplasm. The schizont stages of certain Theileria species induce a unique, cancer-like, phenotype in infected host leukocytes. Theileria undergoes an obligate sexual cycle, involving fusion of gametes in the tick gut, to produce a transiently diploid zygote. The existence of sexual recombination in T. parva has been confirmed in the laboratory, and is presumed to contribute to the extensive polymorphism observed in field isolates. Key parameters in T. parva population dynamics are the relative importance of asymptomatic carrier cattle and animals undergoing severe disease, in transmission of the parasite to ticks, and the extent of transmission by nymphs as compared to adult ticks. Tick populations differ in vector competence for specific T. parva stocks. Recombinant forms of T. parva and T. annulata sporozoite surface antigens induce protection against parasite challenge in cattle. In future, vaccines might be improved by inclusion of tick peptides in multivalent vaccines.
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Affiliation(s)
- R Bishop
- The International Livestock Research Institute, P.O. Box 30709, Nairobi, Kenya.
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Effects of
Macrocheles
mites on longevity of males of the dimorphic dung beetle
Onthophagus binodis. J Zool (1987) 2006. [DOI: 10.1017/s0952836901000930] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
East Coast fever (ECF) is the most important tick-borne disease in eastern, central and southern Africa and caused an estimated loss of US $186 million in 1989 in the 11 countries where it occurs. It was brought to southern Africa with cattle from Tanzania in 1901 and, over the next 3 years, devastated the cattle that had survived the rinderpest pandemic of the 1890s. Chemical control of ticks using arsenical compounds was introduced in the early 1900s and became the main control measure for both ticks and the diseases they transmit. This method of control has become less reliable over the last 30 years for many reasons, including reduced government spending on livestock and extension, the cost of acaricides, acaricide resistance, poor management of dips and spray races, and poor application of cattle movement control and quarantine. Significant advances in immunization and treatment have been made in the last 30 years, and more robust integrated strategies combining immunization, reduced frequency of chemical control and treatment are being adopted or considered. Throughout its history, ECF has been a source of great anxiety and cost to farmers, and of intense interest to research workers. Many dogmas and misconceptions have become established, some of which still flourish while others took years to demolish. This paper briefly reviews these as well as the history of the disease and explores recent epidemiological findings and their relevance to applying effective control.
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Young AS, Dolan TT, Morzaria SP, Mwakima FN, Norval RA, Scott J, Sherriff A, Gettinby G. Factors influencing infections in Rhipicephalus appendiculatus ticks fed on cattle infected with Theileria parva. Parasitology 1996; 113 ( Pt 3):255-66. [PMID: 8811850 DOI: 10.1017/s0031182000082020] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A large database on the transmission of a stabilate of the Theileria parva Muguga stock from one breed of cattle using two stocks of Rhipicephalus appendiculatus, Muguga and Ol Pejeta was developed and analysed. Factors associated with the ticks and cattle, and the infections developing in cattle were studied in relation to the infection variables in the tick batches harvested daily from cattle. Generalized Linear Interactive Modelling (GLIM) was used to determine the importance of factors and interactions in influencing the levels of tick infection variables using Type I and Type III sums of squares analyses. Analysis of the 6 variables, prevalence (percentage of ticks infected), abundance (mean number of infected salivary gland acini per tick examined) and intensity (mean number of infected salivary gland acini per infected tick) in batches of 30 male and 30 female ticks showed that 24 covariates, factors or interactions had a significant effect (P < 0.05). Certain covariates and factors were particularly important for all 6 tick infection variables; parasitaemia of animal on the day of tick harvest, stabilate dilution administered to animal, month in which tick batch was harvested, minimum packed cell volume of animal over the sampling period, age of animal, and the minimum leukocyte count of the animal over the sampling period. The GLIM analyses were found to be a useful tool in identifying factors that influence infection levels and in devising methods of producing tick batches with more predictable infections.
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Affiliation(s)
- A S Young
- International Livestock Research Institute, Nairobi, Kenya
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Shaw MK, Young AS. Differential development and emission of Theileria parva sporozoites from the salivary gland of Rhipicephalus appendiculatus. Parasitology 1995; 111 ( Pt 2):153-60. [PMID: 7675529 DOI: 10.1017/s0031182000064891] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The initiation of feeding of infected Rhipicephalus appendiculatus adults induces the rapid development of Theileria parva sporoblasts within the salivary gland acini leading to the production of numerous sporozoites which are inoculated into the mammalian host initiating infection. In this study the pattern of development, host cell specificity and emission of T. parva sporozoites within the salivary glands of heavily infected, 4-day fed adult R. appendiculatus ticks was examined. Infected acini were randomly distributed throughout the salivary gland. Sporozoite development within each gland was not synchronized and wide variation in the rate of parasite development, which correlated with the secretory activity of the individual acinus, was observed in all glands examined. Previous studies had shown that T. parva developed primarily in Type III 'e' cells. However, in heavily infected salivary glands sporogony and the emission of mature sporozoites also occurred in 'c' cells of Type II acini. Sporozoite emission from infected cells occurred by a process similar to apocrine secretion. The loss of the apical membrane of the infected cell allowed sporozoites free access to the lumen of the acinus and into the collecting ducts of the salivary gland. Sporozoite discharge was gradual since few parasites were found in the acinus valve or in the collecting ducts. Furthermore, the small size of the acinar valve aperature ensures that only small numbers of sporozoites can be released at any one time from an infected acinus.
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Affiliation(s)
- M K Shaw
- International Laboratory for Research on Animal Diseases, Nairobi, Kenya
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