Sexual and transovarian transmission of Crimean-Congo haemorrhagic fever virus in Hyalomma truncatum ticks

Gonzalez, Jean-Paul; Camicas, Jean-Louis; Cornet, Jean-Paul; Faye, Ousmane; Wilson, Mark L.

doi:10.1016/s0923-2516(06)80073-7

Cited by 103 publications

(73 citation statements)

References 12 publications

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“…Immature ticks can be infected through feeding on viraemic, small vertebrate hosts and through transovarial transmission from the adult female tick. Interpretation of data from Gonzalez et al (1992) suggests that the proportion of infected nymphs from an infected female Hyalomma truncatum tick may be low. Logan et al (1989) demonstrated that the overall CCHFV infection rate for larval H. truncatum ticks after engorging on viraemic newborn mice was only 4AE4%, and in endemic regions, only a proportion of those small mammal hosts on which the larvae feed will be infected and viraemic.…”

Section: Methodsmentioning

confidence: 99%

Impact of climate change on risk of incursion of Crimean-Congo haemorrhagic fever virus in livestock in Europe through migratory birds

Gale¹,

Stephenson²,

Brouwer³

et al. 2011

Journal of Applied Microbiology

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To predict the risk of incursion of Crimean-Congo haemorrhagic fever virus (CCHFV) in livestock in Europe introduced through immature Hyalomma marginatum ticks on migratory birds under current conditions and in the decade 2075-2084 under a climate-change scenario. A spatial risk map of Europe comprising 14 282 grid cells (25 × 25 km) was constructed using three data sources: (i) ranges and abundances of four species of bird which migrate from sub-Saharan Africa to Europe each spring, namely Willow warbler (Phylloscopus trochilus), Northern wheatear (Oenanthe oenanthe), Tree pipit (Anthus trivialis) and Common quail (Coturnix coturnix); (ii) UK Met Office HadRM3 spring temperatures for prediction of moulting success of immature H. marginatum ticks and (iii) livestock densities. On average, the number of grid cells in Europe predicted to have at least one CCHFV incursion in livestock in spring was 1·04 per year for the decade 2005-2014 and 1·03 per year for the decade 2075-2084. In general with the assumed climate-change scenario, the risk increased in northern Europe but decreased in central and southern Europe, although there is considerable local variation in the trends. The absolute risk of incursion of CCHFV in livestock through ticks introduced by four abundant species of migratory bird (totalling 120 million individual birds) is very low. Climate change has opposing effects, increasing the success of the moult of the nymphal ticks into adults but decreasing the projected abundance of birds by 34% in this model. For Europe, climate change is not predicted to increase the overall risk of incursion of CCHFV in livestock through infected ticks introduced by these four migratory bird species

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Section: Methodsmentioning

confidence: 99%

Impact of climate change on risk of incursion of Crimean-Congo haemorrhagic fever virus in livestock in Europe through migratory birds

Gale¹,

Stephenson²,

Brouwer³

et al. 2011

Journal of Applied Microbiology

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“…Competent tick vectors of CCHFV are defined by their ability to support viral replication in their tissues during metamorphosis from larva to nymph to adult, to transmit the virus from adult females to their eggs and from adult males to females during copulation (Dohm et al, 1996;Gordon et al, 1993;Logan et al, 1990;Shepherd et al, 1991;Gonzalez et al, 1992). Following its ingestion by a competent vector in a blood meal, CCHFV replicates in the lining of the tick's midgut, then spreads to many different tissues, reaching the highest titers in the salivary glands and reproductive organs (Dickson and Turell, 1992).…”

Section: Vertical Transmissionmentioning

confidence: 99%

“…Substances present in tick saliva appear to enhance the transmission of virus by co-feeding (Shepherd et al, 1989b). In adult females, such direct exposures may enhance the rate of transovarial transmission (Gonzalez et al, 1992;Nuttall et al, 1994;Randolph, 2011).…”

Section: Horizontal Transmissionmentioning

confidence: 99%

Crimean-Congo hemorrhagic fever: History, epidemiology, pathogenesis, clinical syndrome and genetic diversity

et al. 2013

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Bente, Dennis A.; Forrester, Naomi L.; Watts, Douglas M.; McAuley, Alexander J.; Whitehouse, Chris A.; and Bray, Mike, "CrimeanCongo hemorrhagic fever: History, epidemiology, pathogenesis, clinical syndrome and genetic diversity" (2013 b s t r a c tCrimean-Congo hemorrhagic fever (CCHF) is the most important tick-borne viral disease of humans, causing sporadic cases or outbreaks of severe illness across a huge geographic area, from western China to the Middle East and southeastern Europe and throughout most of Africa. CCHFV is maintained in vertical and horizontal transmission cycles involving ixodid ticks and a variety of wild and domestic vertebrates, which do not show signs of illness. The virus circulates in a number of tick genera, but Hyalomma ticks are the principal source of human infection, probably because both immature and adult forms actively seek hosts for the blood meals required at each stage of maturation. CCHF occurs most frequently among agricultural workers following the bite of an infected tick, and to a lesser extent among slaughterhouse workers exposed to the blood and tissues of infected livestock and medical personnel through contact with the body fluids of infected patients. CCHFV is the most genetically diverse of the arboviruses, with nucleotide sequence differences among isolates ranging from 20% for the viral S segment to 31% for the M segment. Viruses with diverse sequences can be found within the same geographic area, while closely related viruses have been isolated in far distant regions, suggesting that widespread dispersion of CCHFV has occurred at times in the past, possibly by ticks carried on migratory birds or through the international livestock trade. Reassortment among genome segments during co-infection of ticks or vertebrates appears to have played an important role in generating diversity, and represents a potential future source of novel viruses. In this article, we first review current knowledge of CCHFV, summarizing its molecular biology, maintenance and transmission, epidemiology and geographic range. We also include an extensive discussion of CCHFV genetic diversity, including maps of the range of the virus with superimposed phylogenetic trees. We then review the features of CCHF, including the clinical syndrome, diagnosis, treatment, pathogenesis, vaccine development and laboratory animal models of CCHF. The paper ends with a discussion of the possible future geographic range of the virus. For the benefit of researchers, we include a Supplementary Table listing all published reports of CCHF cases and outbreaks in the English-language literature, plus some principal articles in other languages, with total case numbers, case fatality rates and all CCHFV strains on GenBank.

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“…The sexual transmission of Chlamydia psittaci in koalas may also involve transmission to offspring (Weigler et al 1988). Several mosquito species have been intensively studied due to their role as vectors of vertebrate diseases, and many researchers have documented the combination of vertical and sexual virus transmission within mosquito populations (Nayar et al 1986;Rosen 1987;Tesh & Modi 1987;Rosen et al 1989;Gonzalez et al 1992). These studies sug-gest that vertical and sexual transmission may be critical to disease maintenance in the vector population in the absence of the vertebrate hosts.…”

Section: Introductionmentioning

confidence: 99%

Interactions between frequency–dependent and vertical transmission in host–parasite systems

Altizer

Augustine

1997

Proc. R. Soc. Lond. B

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SUMMARYWe investigate host-pathogen dynamics and conditions for coexistence in two models incorporating frequency-dependent horizontal transmission in conjunction with vertical transmission. The first model combines frequency-dependent and uniparental vertical transmission, while the second addresses parasites transmitted vertically via both parents. For the first model, we ask how the addition of vertical transmission changes the coexistence criteria for parasites transmitted by a frequencydependent horizontal route, and show that vertical transmission significantly broadens the conditions for parasite invasion. Host-parasite coexistence is further affected by the form of density-dependent host regulation. Numerical analyses demonstrate that within a host population, a parasite strain with horizontal frequency-dependent transmission can be driven to extinction by a parasite strain that is additionally transmitted vertically for a wide range of parameters. Although models of asexual host populations predict that vertical transmission alone cannot maintain a parasite over time, analysis of our second model shows that vertical transmission via both male and female parents can maintain a parasite at a stable equilibrium. These results correspond with the frequent co-occurrence of vertical with sexual transmission in nature and suggest that these transmission modes can lead to host-pathogen coexistence for a wide range of systems involving hosts with high reproductive rates.

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Sexual and transovarian transmission of Crimean-Congo haemorrhagic fever virus in Hyalomma truncatum ticks

Cited by 103 publications

References 12 publications

Impact of climate change on risk of incursion of Crimean-Congo haemorrhagic fever virus in livestock in Europe through migratory birds

Impact of climate change on risk of incursion of Crimean-Congo haemorrhagic fever virus in livestock in Europe through migratory birds

Crimean-Congo hemorrhagic fever: History, epidemiology, pathogenesis, clinical syndrome and genetic diversity

Interactions between frequency–dependent and vertical transmission in host–parasite systems

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