Epizootiological investigation of a Q fever outbreak and implications for future control strategies.

OBJECTIVE: To describe the epizootiological investigation of an outbreak of Q fever (Coxiella burnetii infection). DESIGN: Epidemiological study. ANIMALS: 17 goat herds in Washington, Montana, and Oregon. PROCEDURES: In April 2011, an abortion storm at a commercial goat farm in Washington was determined to be caused by C burnetii. A joint epidemiological investigation by public health and veterinary professionals was subsequently performed to assess the extent of the outbreak by performing a trace-forward of goats sold from the index farm, to determine risk factors associated with infection, and to implement control measures. A herd management plan was developed to control the outbreak and reduce risk of human exposure. Quarantine and temporary holds preventing the sale or movement of goats allowed time for trace-forward investigation, education of farmers regarding disease risk, and testing to determine the scope of the outbreak. RESULTS: 17 farms were affected; 21 human Q fever cases were identified. Bacterial shedding in feces, vaginal fluid, or milk was confirmed in 156 of 629 (25%) goats tested by PCR assay. Seroprevalence of antibodies against C burnetii in goats, determined by ELISA, was 12%. The risk for C burnetii infection in goats was highest among females, those on farms associated with human Q fever, and those on Washington farms. A protective effect was observed for goats at farms where the primary form of goat carcass disposal was burial. CONCLUSIONS AND CLINICAL RELEVANCE: This outbreak illustrated the importance of a joint investigation for zoonotic pathogens and the need to expand and strengthen relationships between medical, public health, and veterinary partners. Heightened awareness and enhanced veterinary diagnostic capabilities for C burnetii are needed to identify and control outbreaks expediently.

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

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.

First reported multistate human Q fever outbreak in the United States, 2011.

In April, 2011, the Q fever bacterium Coxiella burnetii was identified at a Washington farm where an abortion storm took place among goats. Soon after, Q fever cases were reported among visitors to the farm from Washington and Montana. A cross-sectional investigation was conducted among humans and goats associated with the index farm or with 16 other farms that purchased goats from the index farm or housed goats at the index farm for breeding purposes. Questionnaire data were analyzed, along with human and goat specimens collected for evidence of C. burnetii infection. Twenty-one persons (19%) of the 109-person cohort from Washington and Montana met the outbreak case definition of an epidemiologic link to the index farm and a C. burnetii Phase II immunoglobulin G (IgG) titer ≥1:128 by immunofluorescence assay. Seventy-one percent of cases (15 of 21) were symptomatic, compared with approximately 50% during previous Q fever outbreaks. National Q fever surveillance reports increase in frequency with age, but 29% (6 of 21) of cases during this outbreak occurred in children aged <14 years. Goat-specific Q fever risk factors included direct contact with a newborn (prevalence ratio [PR] 10.7; confidence interval [CI] 1.5, 77.4), exposure to a newborn that died (PR 5.5; CI 1.7, 18.2), exposure to a weak newborn (PR 4.4; CI 1.7, 11.6), living on a property with goats (PR 4.2; CI 1.3, 13.9), and direct contact with birth/afterbirth products (PR 2.8; CI 1.1, 6.9). Evidence of C. burnetii infection was detected in all 17 goat herds sampled (13 Washington, 3 Montana, 1 Oregon) by PCR and/or enzyme-linked immunosorbent assay. Following this investigation, Washington and Montana implemented a herd management plan to encourage best-management practices among livestock owners, reduce the potential for future outbreaks, and promote continued communication between state public health and agricultural authorities.

Clinician assessment for Coxiella burnetii infection in hospitalized patients with potentially compatible illnesses during Q fever outbreaks and following a health alert, Montana, 2011.

BACKGROUND: Coxiella burnetii is an endemic bacterial pathogen in the United States and the causative agent of Q fever. Two outbreaks of Q fever occurred in Montana during 2011, which led to the issuance of a health alert urging clinicians to test patients with Q fever-compatible illnesses for C. burnetii infection. METHODS: We retrospectively evaluated the medical records of patients hospitalized for fever, pneumonia, chest pain, and viral infection of unknown etiologies during the two Q fever outbreaks and following the health alert. RESULTS: A total of 103 patients were included in the analysis. Clinicians assessed<1% of patients suffering illnesses compatible with Q fever for known risk factors or C. burnetii infection. Only 1 patient had Q fever excluded as a diagnosis. CONCLUSION: Clinicians should assess for Q fever risk factors and consider the diagnosis in patients hospitalized with Q fever-compatible illnesses when the etiology of illness is unknown. Work is warranted to evaluate the effectiveness of current healthcare alert practices for zoonotic diseases.

Presence and persistence of Coxiella burnetii in the environments of goat farms associated with a Q fever outbreak.

Q fever is a zoonotic disease caused by inhalation of the bacterium Coxiella burnetii. Ruminant livestock are common reservoirs for C. burnetii, and bacteria present in aerosols derived from the waste of infected animals can infect humans. The significance of infection from material deposited in the environment versus transmission directly from infected animals is not known. In 2011, an outbreak of Q fever cases on farms in Washington and Montana was associated with infected goats. A study was undertaken to investigate the quantity and spatial distribution of C. burnetii in the environment of these goat farms. Soil, vacuum, and sponge samples collected on seven farms epidemiologically linked to the outbreak were tested for the presence of C. burnetii DNA by quantitative PCR. Overall, 70.1% of the samples were positive for C. burnetii. All farms had positive samples, but the quantity of C. burnetii varied widely between samples and between farms. High quantities of C. burnetii DNA were in goat housing/birthing areas, and only small quantities were found in samples collected more than 50 m from these areas. Follow-up sampling at one of the farms 1 year after the outbreak found small quantities of C. burnetii DNA in air samples and large quantities of C. burnetii persisting in soil and vacuum samples. The results suggest that the highest concentrations of environmental C. burnetii are found in goat birthing areas and that contamination of other areas is mostly associated with human movement.

Q Fever with unusual exposure history: a classic presentation of a commonly misdiagnosed disease.

We describe the case of a man presumptively diagnosed and treated for Rocky Mountain spotted fever following exposure to multiple ticks while riding horses. The laboratory testing of acute and convalescent serum specimens led to laboratory confirmation of acute Q fever as the etiology. This case represents a potential tickborne transmission of Coxiella burnetii and highlights the importance of considering Q fever as a possible diagnosis following tick exposures.

A case of person-to-person transmission of Q fever from an active duty serviceman to his spouse.

Coxiella burnetii has recently gained military relevance given its potential as a bioterrorism agent, and the multiple cases reported among U.S. military personnel deployed to the Middle East. Sexual transmission of Q fever is rare but has been reported in the literature. We describe the possible sexual transmission of Q fever from a returning serviceman from Iraq to his wife. In a recent editorial commentary, Dr. Raoult wrote about the reemergence of Q fever after September 11, 2001 (Raoult 2009). Indeed, C. burnetii has gained military relevance given its potential as a bioterrorism agent and the multiple cases reported among military personnel deployed in Southwest/Central Asia and North Africa (Botros et al. 1995 , Meskini et al. 1995 , Leung-Shea and Danaher 2006 ). Human serosurveys in these geographic areas have reported prevalence rates for Q fever ranging from 10% to 37% in contrast to the United States, which has an estimated Q fever seroprevalence of 3.1% (Botros et al. 1995, Meskini et al. 1995, Anderson et al. 2009). There is no data available for Q fever seroprevalence in Iraq. As a consequence, native populations in these regions may be more likely to possess immunity, and newcomers, such as U.S. military personnel, would be vulnerable to acute infection (Derrick 1973). We report on the possible sexual transmission of C. burnetii from a serviceman in the late recovery of acute Q fever to his wife.

Seroprevalence of Q fever in the United States, 2003-2004.

We performed serum testing for IgG antibodies against Coxiella burnetii (phase I and phase II) and analyzed questionnaire data from 4,437 adults > or = 20 years of age who participated in the National Health and Nutrition Examination Survey 2003-2004 survey cycle. National Q fever seroprevalence was determined by enzyme-linked immunosorbent assay and confirmed by using immunofluorescent antibody testing. Overall seroprevalence for Coxiella burnetii was 3.1% (95% confidence interval [CI] = 2.1-4.3%) among 4,437 adults > or = 20 years of age. Coxiella burnetii age-adjusted antibody prevalence was higher for men than for women (3.8%, 95% CI = 2.7-5.2% versus 2.5%, 95% CI = 1.5-3.7%, respectively, P < 0.05). Mexican Americans had a significantly higher antibody prevalence (7.4%, 95% CI = 6.6-8.3%) than either non-Hispanic whites (2.8%, 95% CI = 1.7-4.3%) or non-Hispanic blacks (1.3%, 95% CI = 0.6-2.5%) (P < 0.001). Multivariate analysis showed that the risk for Q fever antibody positivity increased with age and was higher among persons who were foreign-born, male, and living in poverty. These findings indicate that the national seroprevalence of Q fever in the United States is higher than expected on the basis of case numbers reported to the Centers for Disease Control and Prevention from state health departments. Potential differences in risk for exposure by race/ethnicity warrant further study.

Cluster of sylvatic epidemic typhus cases associated with flying squirrels, 2004-2006.

In February 2006, a diagnosis of sylvatic epidemic typhus in a counselor at a wilderness camp in Pennsylvania prompted a retrospective investigation. From January 2004 through January 2006, 3 more cases were identified. All had been counselors at the camp and had experienced febrile illness with myalgia, chills, and sweats; 2 had been hospitalized. All patients had slept in the same cabin and reported having seen and heard flying squirrels inside the wall adjacent to their bed. Serum from each patient had evidence of infection with Rickettsia prowazekii. Analysis of blood and tissue from 14 southern flying squirrels trapped in the woodlands around the cabin indicated that 71% were infected with R. prowazekii. Education and control measures to exclude flying squirrels from housing are essential to reduce the likelihood of sylvatic epidemic typhus.

A waterborne outbreak of Norwalk-like virus among snowmobilers-Wyoming, 2001.

In February 2001, episodes of acute gastroenteritis were reported to the Wyoming Department of Health from persons who had recently vacationed at a snowmobile lodge in Wyoming. A retrospective cohort study found a significant association between water consumption and illness, and testing identified Norwalk-like virus (NLV) in 8 of 13 stool samples and 1 well. Nucleotide sequences from the positive well-water specimen and 6 of the positive stool samples were identical. This multistrain NLV outbreak investigation illustrates the importance of NLV as a cause of waterborne illness and should encourage monitoring for NLVs in drinking water.

Public health consequences of use of antimicrobial agents in food animals in the United States.

The use of antimicrobial agents in food animals has caused concern regarding the impact these uses have on human health. Use of antimicrobial agents in animals and humans results in the emergence and dissemination of resistant bacteria. Resistant bacteria from food animals may be passed through the food chain to humans resulting in resistant infections. Increasing resistance to antimicrobial agents that are important in the treatment of human diseases, such as fluoroquinolones and third-generation cephalosporins for the treatment of Salmonella and Campylobacter infections, has significant public health implications. Efforts to mitigate the effects of increasing resistance require collaboration by several partners, including the farming, veterinary, medical, and public health communities.