Abstract
Q fever and rickettsial diseases occur throughout the world and appear to be emergent zoonoses in Chile. The diagnosis of these diseases is currently uncommon in Chile, as their clinical presentations are non-specific and appropriate diagnostic laboratory assays are of limited availability. During a recent outbreak of undiagnosed human atypical pneumonia, we serologically investigated a series of 357 cases from three regions of southern Chile. The aim was to identify those caused by Coxiella burnetii and/or Rickettsia spp. Serological analysis was performed by ELISA and an immunofluorescence assay (IFA) for acute and convalescence sera of patients. Our results, including data from two international reference laboratories, demonstrate that 71 (20%) of the cases were Q fever, and 44 (15%) were a likely rickettsial infection, although the rickettsial species could not be confirmed by serology. This study is the first report of endemic Q fever and rickettsial disease affecting humans in Chile.
Highlights
Both coxielloses and rickettsioses are primarily zoonotic diseases with a worldwide distribution
In July 2017, in the Los Lagos Region from Chile, an unusual outbreak of atypical pneumonia was detected that affected dairy farm workers and family members
In order to determine the potential pathogen or pathogens involved in the outbreak, acute sera of the first 32 cases were sent to National Microbiology Laboratory of Canada (NML)
Summary
Both coxielloses and rickettsioses are primarily zoonotic diseases with a worldwide distribution. The reservoir and mechanism of dissemination of the bacterium causing Q fever are complex and often involve unknown factors [1]. The causative agent is Coxiella burnetii, a small Gram-negative, pleomorphic bacterium belonging to the order Legionellales that grows intracellularly within eukaryotic cells [2,3]. The main reservoir consists of ruminant animals (goats, sheep, and cattle) in which the infection can be asymptomatic or produce reproductive disorders, such as reduced fertility, abortions, endometritis, and infertility [3,4]. Humans are infected through the inhalation of contaminated aerosols or contact with infectious urine, feces, unpasteurized milk, amniotic fluid, placental tissues, or abortion debris from infected animals [6]. C. burnetii has a significant capacity for long-term survival in the environment owing to a pseudosporulation process, which is an important factor in its dissemination [3]
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