Increasing Risks of Introduction of Heartwater onto the American Mainland Associated with Animal Movements

Abstract

Opportunities to introduce heartwater onto the American mainland through animal movements include importation from Africa of tick-infested reptiles and of subclinically infected wild ungulates and importation of livestock from islands in the Caribbean infested with Amblyomma variegatum ticks. Measures to control importation of heartwater vectors on reptiles include importation bans of infested species, treatment of imported reptiles, and eradication of established infestations on the American mainland. Measures to control importation of infected wildlife must focus on improved methods, such as the PCR assay, of screening animals to prevent the entry of carriers of Cowdria ruminantium. Measures to control importation of infected animals from the Caribbean must be based on knowledge of the islands that are infected with C. ruminantium so that the risk of dissemination of heartwater can be established.

Progress and obstacles in vaccine development for the ehrlichioses

“…E. ruminantium is responsible for major production losses to the African livestock industry, and is also considered to pose a potential danger to the southeastern USA where competent native tick vectors are present [20-22] and the climate is appropriate for introduction of exotic tick species capable of transmitting the disease [23-25]. In Africa, E. ruminantium is transmitted by Amblyomma variegatum and Amblyomma hebraeum, but other Amblyomma spp.…”

Development of Loop-Mediated Isothermal Amplification (LAMP) Assays for Rapid Detection of Ehrlichia ruminantium

“…Heartwater is not only responsible for high economic losses in endemic countries [2], but is also suggested to be a potential emerging zoonosis since the PCR and sequence detection of the pathogen's presence in three fatal human cases although the cytological examination and bacterial isolation were not achieved [3,4]. The disease is established in nearly all countries of sub-Saharan Africa and some islands of the Caribbean, from where it threatens the American mainland [5]. In the USA, three Ehrlichia species, namely E. canis , E. chaffeensis , and E. ewingii , are known to exist [6-11].…”

Comparative Genomic Analysis of Three Strains of Ehrlichia ruminantium Reveals an Active Process of Genome Size Plasticity

“…This tick-borne member of the Rickettsiales, an ␣-proteobacterium, is a small, gram-negative, aerobic, obligate intracellular pathogen of endothelial cells that can cause up to 90% mortality in susceptible animals. Heartwater is responsible for great economic losses in Africa (48) but also represents a threat to the American mainland owing to the presence of potentially transmitting ticks (8,17). The control strategy is based on vector eradication and immunization, a strategy possible only on islands, where the incoming flow of ticks is highly limited (53).…”