China
Africa
Explore chapters and articles related to this topic
Ticks
Published in Gail Miriam Moraru, Jerome Goddard, The Goddard Guide to Arthropods of Medical Importance, Seventh Edition, 2019
Gail Miriam Moraru, Jerome Goddard
Ehrlichia are organisms in the family Anaplasmataceae that primarily infect circulating leukocytes. Much of the knowledge gained concerning ehrlichiae has come from the veterinary sciences, with intensive studies on Ehrlichia (Cowdria) ruminantium (cattle, sheep, goats), and Ehrlichia equi (horses). Canine ehrlichiosis, caused by Ehrlichia canis, wiped out 200 to 300 military working dogs during the Vietnam War.58 In the United States, human cases of ehrlichiosis were unknown until a report in March 1986 of a 51-year-old man who had been bitten by a tick in Arkansas and was sick for 5 days before being admitted to a hospital in Detroit.59 He had malaise, fever, headache, myalgia, pancytopenia, abnormal liver function, renal failure, and high titers of E. canis antibodies that fell sharply during convalescence. The patient was thought to have the dog disease. It turned out not to be the case; he had an infection with E. chaffeensis (a hitherto unknown agent). For this reason, in the literature, there are several reports of human infection in the United States with E. canis, when, in fact, human ehrlichiosis is usually caused by one to three closely related Ehrlichia organisms as follows. One of these, Ehrlichia chaffeensis, the most frequently reported, is the causative agent of human monocytic ehrlichiosis (HME), which occurs mostly in the southern and southcentral United States (sporadic cases of HME have also been reported in Europe) and infects mononuclear phagocytes in blood and tissues.60 HME is not an insignificant disease—1288 cases were reported to the CDC in 2015 (Figure 30.6).18 The second, E. ewingii, mostly a dog and deer pathogen, infects granulocytes and causes a clinical illness similar to HME but thus far has only been identified in a few patients, most of whom were immune-compromised. The disease became reportable in 2008; however, a recent study suggests that cases of E. ewingii infection are underreported.61 The third ehrlichial agent, the E. muris-like agent (sometimes called EMLA or E. eauclairensis), causes fever, malaise, headache, lymphopenia, and elevated liver enzymes.62 Thus far, it has only been reported in a couple hundred patients from the upper midwestern United States, and the agent is transmitted by the deer tick, Ixodes scapularis. 63
How relevant are in vitro culture models for study of tick-pathogen interactions?
Published in Pathogens and Global Health, 2021
Cristiano Salata, Sara Moutailler, Houssam Attoui, Erich Zweygarth, Lygia Decker, Lesley Bell-Sakyi
The immunodominant surface proteins of the human pathogen Ehrlichia chaffeensis, and the closely related canine pathogen Ehrlichia canis, are encoded by multigene families. Protein expression studies of E. chaffeensis and E. canis grown in tick cell lines [44,139] confirmed previous observations on differential transcription of genes encoding their immunodominant outer membrane proteins in tick and mammalian hosts [140,141]. Two of the proteins encoded by members of the E. chaffeensis p28-Omp multigene family were predominantly expressed in infected canine macrophage (DH82) cultures, whereas a single, different p28-Omp protein was expressed in infected vector (AAE2) and non-vector (ISE6) tick cell lines [44,139]. Similarly, three of the proteins encoded by the E. canis p30-Omp multigene family were expressed in infected DH82 cultures, while the protein encoded by a single, different p30-Omp member was expressed in infected, non-vector (ISE6) tick cells.
A novel Ehrlichia strain (Rickettsiales: Anaplasmataceae) detected in Amblyomma triste (Acari: Ixodidae), a tick species of public health importance in the Southern Cone of America
Published in Pathogens and Global Health, 2020
Gabriel L. Cicuttin, María N. De Salvo, Paula Díaz Pérez, Darío Silva, María L. Félix, José M. Venzal, Santiago Nava
Bacteria of the genus Ehrlichia (Rickettsiales: Anaplasmataceae) are alpha-proteobacterial, tick-transmitted, obligate intracellular parasites with medical and veterinary importance that can infect monocytes, neutrophils, endothelial cells or neutrophils [1,2]. Formally there are six recognized species: Ehrlichia canis, Ehrlichia chaffeensis, Ehrlichia ewingii, Ehrlichia ruminantium, Ehrlichia muris and Ehrlichia minasensis, but different strains of putative novel species of Ehrlichia have been molecularly detected in the last 20 years [1–14, among others].
Seropositivity to Midichloria mitochondrii (order Rickettsiales) as a marker to determine the exposure of humans to tick bite
Published in Pathogens and Global Health, 2019
Valentina Serra, Viktoria Krey, Christina Daschkin, Alessandra Cafiso, Davide Sassera, Horst-Günter Maxeiner, Letizia Modeo, Carsten Nicolaus, Claudio Bandi, Chiara Bazzocchi
Ticks are among the most important vectors of pathogens, causing human and animal diseases, in tropical, sub-tropical and temperate countries [1]. Approximately 10% of tick species are estimated to play a role in the transmission of a total of over 200 pathogens [2,3] including zoonotic bacteria (e.g. Borrelia burgdorferi sensu lato, Rickettsia rickettsii, Coxiella burnetii, Ehrlichia canis, Francisella tularensis [2]) and viruses (e.g. tick-borne encephalitis virus, Crimean-Congo hemorrhagic fever virus [2,4]).