Unique Strain of Rickettsia parkeri Associated with the Hard Tick Dermacentor parumapertus Neumann in the Western United States.

In 1953, investigators at the Rocky Mountain Laboratories in Hamilton, MT, described the isolation of a spotted fever group (SFGR) species from ticks collected from black-tailed jackrabbits () in northern Nevada. Several decades later, investigators characterized this SFGR (designated the parumapertus agent) by using mouse serotyping methods and determined that it represented a distinct rickettsial serotype closely related to ; nonetheless, the parumapertus agent was not further characterized or studied. To our knowledge, no isolates of the parumapertus agent remain in any rickettsial culture collection, which precludes contemporary phylogenetic placement of this enigmatic SFGR.

Cardiac Tropism of Borrelia burgdorferi: An Autopsy Study of Sudden Cardiac Death Associated with Lyme Carditis.

Fatal Lyme carditis caused by the spirochete Borrelia burgdorferi rarely is identified. Here, we describe the pathologic, immunohistochemical, and molecular findings of five case patients. These sudden cardiac deaths associated with Lyme carditis occurred from late summer to fall, ages ranged from young adult to late 40s, and four patients were men.

Routine argyrophil techniques detect in tissues of patients with fatal Rocky Mountain spotted fever.

, a bacterial tickborne pathogen that causes Rocky Mountain spotted fever (RMSF), stains poorly or not at all with conventional tissue Gram techniques, and contemporary visualization of the pathogen in formalin-fixed, paraffin-embedded tissues has relied almost entirely on immunohistochemical staining methods that are generally limited to specialized research laboratories or national reference centers. To our knowledge, previously described argyrophil-based histochemical techniques have not successfully detected rickettsiae in formalin-fixed, paraffin-embedded tissues. To investigate the ability of standard silver impregnation techniques to demonstrate the occurrence and distribution of in tissues of patients with RMSF confirmed by molecular and immunohistochemical methods, three widely recognized and commercially available silver impregnation methods (Warthin-Starry, Steiner, and Dieterle's) were applied to various tissues obtained at autopsy from 10 patients with fatal RMSF.

Humanized Mouse Model of Ebola Virus Disease Mimics the Immune Responses in Human Disease.

Animal models recapitulating human Ebola virus disease (EVD) are critical for insights into virus pathogenesis. Ebola virus (EBOV) isolates derived directly from human specimens do not, without adaptation, cause disease in immunocompetent adult rodents. Here, we describe EVD in mice engrafted with human immune cells (hu-BLT).

Comparison of Monkeypox Virus Clade Kinetics and Pathology within the Prairie Dog Animal Model Using a Serial Sacrifice Study Design.

Monkeypox virus (MPXV) infection of the prairie dog is valuable to studying systemic orthopoxvirus disease. To further characterize differences in MPXV clade pathogenesis, groups of prairie dogs were intranasally infected (8 × 10(3) p.f.

A combined oral contraceptive affects mucosal SHIV susceptibility factors in a pigtail macaque (Macaca nemestrina) model.

Background: Injectable hormonal contraception may increase women's risk of HIV acquisition and can affect biological risk factors in animal models of HIV. We established, for the first time, a model to investigate whether combined oral contraceptives (COC) alter SHIV susceptibility in macaques.

Methods: Seven pigtail macaques were administered a monophasic levonorgestrel (LNG)/ethinyl estradiol (EE) COC at 33% or 66% of the human dose for 60 days.

Notes from the field: update on Lyme carditis, groups at high risk, and frequency of associated sudden cardiac death--United States.

On December 13, 2013, MMWR published a report describing three cases of sudden cardiac death associated with Lyme carditis. State public health departments and CDC conducted a follow-up investigation to determine 1) whether carditis was disproportionately common among certain demographic groups of patients diagnosed with Lyme disease, 2) the frequency of death among patients diagnosed with Lyme disease and Lyme carditis, and 3) whether any additional deaths potentially attributable to Lyme carditis could be identified. Lyme disease cases are reported to CDC through the Nationally Notifiable Disease Surveillance System; reporting of clinical features, including Lyme carditis, is optional.