Q fever in the United States: summary of case reports from two national surveillance systems, 2000-2012

Abstract

Q fever is a worldwide zoonosis historically associated with exposure to infected livestock. This study summarizes cases of Q fever, a notifiable disease in the United States, reported to the Centers for Disease Control and Prevention through two national surveillance systems with onset during 2000-2012. The overall incidence rate during this time was 0.38 cases per million persons per year. The reported case fatality rate was 2.0%, and the reported hospitalization rate was 62%. Most cases (61%) did not report exposure to cattle, goats, or sheep, suggesting that clinicians should consider Q fever even in the absence of livestock exposure. The prevalence of drinking raw milk among reported cases of Q fever (8.4%) was more than twice the national prevalence for the practice. Passive surveillance systems for Q fever are likely impacted by underreporting and underdiagnosis because of the nonspecific presentation of Q fever.

Figure 1.

Reported incidence rate of Q fever cases per million persons per year. Cases were reported to the National Notifiable Disease Surveillance System, and the population at risk was calculated from the Census Bureau population estimates., Cases were reported as Q fever from 2000 to 2007 and as acute or chronic Q fever for 2008–2012.

Figure 2.

Frequency of reported cases of Q fever versus month of onset of symptoms. Cases were reported to the National Notifiable Disease Surveillance System. Cases were reported as Q fever from 2000 to 2007 and as acute or chronic Q fever for 2008–2012.

Figure 3.

Reported incidence rate of Q fever per million persons per year by age group. (A) Q fever, 2000–2007. (B) Acute Q Fever, 2008–2012. (C) Chronic Q fever, 2008–2012. Cases were reported to the National Notifiable Disease Surveillance System and the population at risk was calculated from the Census Bureau population estimates.,