The role of males of the bont tick (Amblyomma hebraeum) in the transmission of Cowdria ruminantium (heartwater)

Andrew, H. R.; Norval, R. A. I.

doi:10.1016/0304-4017(89)90159-3

Cited by 20 publications

(12 citation statements)

References 12 publications

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“…The movement of Dermacentor andersoni males has also been observed in cattle (Stiller and Coan, ). The movement of male ticks towards females may be influenced by sex pheromones released by females (Rechav et al., ; Andrew and Norval, ).…”

Section: Discussionmentioning

confidence: 99%

Evidence of Transstadial and Mechanical Transmission of Lumpy Skin Disease Virus byAmblyomma hebraeumTicks

Lubinga

Tuppurainen

Mahlare

et al. 2013

Transbound Emerg Dis

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Lumpy skin disease (LSD) is an economically important disease caused by LSD virus (LSDV), a Capripoxvirus, characterized by fever and circumscribed skin lesions. It is suspected to be transmitted mechanically by biting flies. To assess the vector potential of Amblyomma hebraeum in transmission of LSDV, mechanical/intrastadial and transstadial modes of transmission of the virus by this tick species were investigated. Two cattle were artificially infected as sources (donors) of infection to ticks. Ticks were infected as either nymphs or adults. Male A. hebraeum ticks were partially fed on donor animals and transferred to recipient animals to test for mechanical/intrastadial transmission. Nymphal A. hebraeum were fed to repletion on donor animals. The emergent adult ticks were placed on recipient animals to test for transstadial transmission of the virus. Successful transmission of LSDV infection was determined in recipient animals by monitoring development of clinical signs, testing of blood for the presence of LSDV by real-time PCR, virus isolation and the serum neutralization test. This report provides further evidence of mechanical/intrastadial and, for the first time, transstadial transmission of LSDV by A. hebraeum. These findings implicate A. hebraeum as a possible maintenance host in the epidemiology of the disease.

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Section: Discussionmentioning

confidence: 99%

Evidence of Transstadial and Mechanical Transmission of Lumpy Skin Disease Virus byAmblyomma hebraeumTicks

Lubinga

Tuppurainen

Mahlare

et al. 2013

Transbound Emerg Dis

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“…Infected nymphs and larvae only become infective in the following instar (32), and infective nymphs or adults transmit E. ruminantium to susceptible hosts without losing the infection. Male A. hebraeum also transfer the infection when moving from infected to susceptible animals in search of mates (44).…”

Section: Vector Biologymentioning

confidence: 99%

Heartwater – Ehrlichia ruminantium infection

Allsopp¹

2015

Rev. Sci. Tech. OIE

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SummaryHeartwater is a notifiable disease that is listed by the World Organisation for Animal Health. It is caused by Ehrlichia ruminantium, an obligately intracellular Gramnegative bacterium in the order Rickettsiales and the family Anaplasmataceae. The disease is borne by ticks in the genus Amblyomma and causes heartwater, or cowdriosis, in wild and domestic ruminants, primarily in Africa, but also in parts of the Caribbean. The disease was recognised in South Africa in the 19th Century and determined to be tick borne in 1900, while the organism was identified in 1925 and first cultured in vitro in 1985. This latter achievement boosted research into the disease at a time when biology was moving into the molecular genetic age. Over the last 20 years, there have been significant improvements in our understanding of E. ruminantium, yielding major advances in diagnosis, epidemiology, genetic characterisation, phylogeny, immunology, and vaccine development. The organism is genetically highly variable; this has important implications for future control measures, and is making it difficult to develop an effective vaccine for protection against tick challenge. Research is continuing into three different types of vaccine, inactivated, attenuated, and recombinant, and the current state of development of each is discussed. KeywordsAmblyomma hebraeum -Amblyomma variegatum -Attenuated vaccine -ControlCowdriosis -Diagnosis -Economic importance -Ehrlichia ruminantium -Heartwater -Inactivated vaccine -Occurrence -Recombinant vaccine -Tick-borne disease.Rev. Sci. Tech. Off. Int. Epiz., 2015, 34 (2), 557-568 AetiologyHeartwater is listed by the World Organisation of Animal Health as a notifiable disease (1). It was known in South Africa for nearly 90 years before the causative organism was identified in 1925 as a rickettsia, originally named Rickettsia ruminantium (2, 3). The name was later changed to Cowdria ruminantium (4), from which arose the term 'cowdriosis'. Molecular phylogenetic studies of the Rickettsiales in the 1990s uncovered the real evolutionary relationships within the order and the organism was reclassified as Ehrlichia ruminantium in the family Anaplasmataceae (5). Ehrlichia ruminantium, which is transmitted by Amblyomma ticks, is obligately intracellular, infects cattle, sheep, goats and some wild ruminants, and is frequently fatal. A comprehensive account of the history and biology of E. ruminantium can be found elsewhere (6). Economic and social importanceHeartwater is a serious economic problem wherever it occurs, in an enormous area covering most of sub-Saharan Africa, its offshore islands, and several islands in the Caribbean. The disease generally prevents livestock farmers from upgrading their herds to modern high-yielding breeds, as these are more susceptible to infection than traditional stock breeds, which often have a measure of resistance (7). Since heartwater is so common in the endemic areas of Africa, farmers are usually unwilling or unable to pay for definitive diagnoses, so it is difficul...

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“…Experimental studies have provided evidence for an epizootiological role of three-host male ticks as intrastadial vectors of A. marginale after interhost transfer (Andrew and Norval, 1989; Coan et al, 1987; Kocan et al, 1992; Stiller and Coan, 1995; Stiller et al, 1987; Stiller et al, 1989; Zaugg et al, 1986). For example, one study involved the release of differentially marked ticks on to an A. marginale -infected calf that was penned with a naive calf.…”

Section: Ticks and The Transmission Of E Canismentioning

confidence: 99%

“…It was also demonstrated in another study that intrastadially infected D. andersoni male ticks could continually transmit A. marginale to multiple hosts without any apparent loss of virulence (Kocan et al, 1992). A. hebraeum males placed on a host infected with E. ruminantium were found to transfer between hosts sharing the same stall in sufficient numbers to transmit a lethal dose of this pathogen (Andrew and Norval, 1989). Furthermore, epidemiological investigations have suggested that one-host tick species such as R .…”

Section: Ticks and The Transmission Of E Canismentioning

confidence: 99%

Host surveys, ixodid tick biology and transmission scenarios as related to the tick-borne pathogen, Ehrlichia canis

Stich

Schaefer

Bremer

et al. 2008

Veterinary Parasitology

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The ehrlichioses have been subject to increasing interest from veterinary and public health perspectives, but experimental studies of these diseases and their etiologic agents can be challenging. Ehrlichia canis, the primary etiologic agent of canine monocytic ehrlichiosis, is relatively well characterized and offers unique advantages and opportunities to study interactions between a monocytotropic pathogen and both its vertebrate and invertebrate hosts. Historically, advances in tick-borne disease control strategies have typically followed explication of tick-pathogen-vertebrate interactions, thus it is reasonable to expect novel, more sustainable approaches to control of these diseases as the transmission of their associated infections are investigated at the molecular through ecological levels. Better understanding of the interactions between E. canis and its canine and tick hosts would also elucidate similar interactions for other Ehrlichia species as well as the potential roles of canine sentinels, reservoirs and models of tick-borne zoonoses. This article summarizes natural exposure studies and experimental investigations of E. canis in the context of what is understood about biological vectors of tick-borne Anaplasmataceae.

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The role of males of the bont tick (Amblyomma hebraeum) in the transmission of Cowdria ruminantium (heartwater)

Cited by 20 publications

References 12 publications

Evidence of Transstadial and Mechanical Transmission of Lumpy Skin Disease Virus byAmblyomma hebraeumTicks

Evidence of Transstadial and Mechanical Transmission of Lumpy Skin Disease Virus byAmblyomma hebraeumTicks

Heartwater – Ehrlichia ruminantium infection

Host surveys, ixodid tick biology and transmission scenarios as related to the tick-borne pathogen, Ehrlichia canis

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