Wind in November, Q fever in December

Outbreak of Q fever associated with a horse-boarding ranch, Colorado, 2005

Coxiella burnetii is a bacterium located worldwide that can cause Q fever when inhaled. We describe an outbreak of Q fever associated with a horse-boarding ranch that had acquired two herds of goats. We conducted case finding and cohort studies among persons who boarded horses on the ranch and ranchers and among residents in the surrounding community, and conducted sampling of the goats and environment, to determine risk factors for infection and guide public health interventions. Sixty-six ranchers and persons who boarded horses on the ranch were interviewed; 62 (94%) were not professional ranchers. Twenty persons (53%) of 38 persons tested had evidence of infection with C. burnetii. Contact with goats was associated with seropositivity, including having helped birth goats (relative risk [RR] 2.4, 95% confidence interval [CI] 1.6-3.6), having had contact with newborn goats (RR 2.3, CI 1.2-4.3), having vaccinated goats (RR 2.1, CI 1.3-3.5), having had contact with stillbirths or newborns that died (RR 2.1, CI 1.2-3.7), and having fed goats (RR 2.1, CI 1.0-4.3). Among 138 tested persons living within 1 mile of the ranch, 11 (8%) demonstrated evidence of C. burnetii infection; eight seropositive persons (73%) had no direct contact with the ranch. Testing of the soil and goats with an IS1111 polymerase chain reaction (PCR) assay confirmed the presence of C. burnetii among the herd and in the environment. This outbreak of Q fever was caused by exposure to infected goats, but exposure to the environment likely played a secondary role. Laypersons should not participate in the birthing process of goats; professionals who come into contact with birthing goats should be educated on reducing their infection risk. This is the first time an IS1111 PCR assay has been used in an outbreak investigation in the United States.

High throughput detection of Coxiella burnetii by real-time PCR with internal control system and automated DNA preparation

Background

Coxiella burnetii is the causative agent of Q-fever, a widespread zoonosis. Due to its high environmental stability and infectivity it is regarded as a category B biological weapon agent. In domestic animals infection remains either asymptomatic or presents as infertility or abortion. Clinical presentation in humans can range from mild flu-like illness to acute pneumonia and hepatitis. Endocarditis represents the most common form of chronic Q-fever. In humans serology is the gold standard for diagnosis but is inadequate for early case detection. In order to serve as a diagnostic tool in an eventual biological weapon attack or in local epidemics we developed a real-time 5'nuclease based PCR assay with an internal control system. To facilitate high-throughput an automated extraction procedure was evaluated.

Results

To determine the minimum number of copies that are detectable at 95% chance probit analysis was used. Limit of detection in blood was 2,881 copies/ml [95%CI, 2,188–4,745 copies/ml] with a manual extraction procedure and 4,235 copies/ml [95%CI, 3,143–7,428 copies/ml] with a fully automated extraction procedure, respectively. To demonstrate clinical application a total of 72 specimens of animal origin were compared with respect to manual and automated extraction. A strong correlation between both methods was observed rendering both methods suitable. Testing of 247 follow up specimens of animal origin from a local Q-fever epidemic rendered real-time PCR more sensitive than conventional PCR.

Conclusion

A sensitive and thoroughly evaluated real-time PCR was established. Its high-throughput mode may show a useful approach to rapidly screen samples in local outbreaks for other organisms relevant for humans or animals. Compared to a conventional PCR assay sensitivity of real-time PCR was higher after testing samples from a local Q-fever outbreak.

[Seroepidemiology of Coxiella burnetii infection among blood donors in Albacete]

INTRODUCTION

The objectives of this study were to determine the prevalence of antibodies to Coxiella burnetii among blood donors and to examine the epidemiological characteristics of C. burnetii infection in Albacete, Spain.

METHODS

A total of 863 serum samples were collected from blood donors aged 18-65 years. Donor samples were stratified by age, sex, and residence (rural or urban). IgG and IgM titers to the C. burnetii phase II antigen were determined by an indirect immunofluorescence assay.

RESULTS

The prevalence of anti-phase II IgG was 23.1%, and three (0.3%) donors had positive IgM titers. Men were more frequently seropositive than women (29% vs. 18%; OR: 1.85; 95% CI: 1.34-2.56), and this difference was not related to differential occupational exposure to animals. Pet ownership had no impact on seroprevalence. In contrast, occupations involving contact with domestic ungulates were associated with a higher seroprevalence (OR: 2.39; 95% CI: 1.04-5.48). Nevertheless, 90% of seropositive donors reported no contact with farm animals.

CONCLUSION

Our results show that C. burnetii infection is highly endemic in Albacete and that most infections are not linked to specific occupational exposure in this area. The high prevalence of antibodies to C. burnetii among blood donors indicates the advisability of studies to determine the risk of transfusion-transmitted Q fever in endemic areas.

“The dust hasn't settled yet”: the National Q fever Management Program, missed opportunities for vaccination and community exposures

AIMS

To determine the proportion of notifiable cases of Q fever attributable to occupational and community exposures and to identify missed opportunities for Q fever vaccination in notifications of occupational exposures.

METHODS

A review of Q fever notifications to the BSPHU from January 2000 to September 2006 was undertaken. Notifications were categorised according to probable exposure source. Occupational exposures were further categorised according to reported past exposure to Q fever and Q fever vaccination status.

RESULTS

One hundred and ninety-one Q fever notifications were identified, with occupational exposure reported in 106 cases and community exposure reported in 69 cases. In the occupational exposures, 76 cases (71%) were not vaccinated, 15 (14%) reported past exposure to Q fever and eight reported vaccination prior to illness onset, but vaccination status could not be independently verified. Community acquired Q fever was most commonly attributed to living or working near a high-risk industry (26, 38%), incidental exposures such as farm visits, or attending sale yards (27, 39%).

CONCLUSIONS

Occupationally acquired cases of Q fever continue to be reported in significant numbers and opportunities for vaccination are being missed. There is an ongoing need to ensure that all employees in high-risk industries are screened and vaccinated. The proportion of community acquired notifications of Q fever has increased since the National Q fever Management Program started, commensurate with the decline in occupationally acquired cases. These proportions may be expected to change with the cessation of the program in Queensland in December 2006.

Wind direction and its linkage with Vibrio cholerae dissemination

BACKGROUND

The relevance of climatic events as causative factors for cholera epidemics is well known. However, examinations of the involvement of climatic factors in intracontinental disease distribution are still absent.

OBJECTIVES

The spreading of cholera epidemics may be related to the dominant wind direction over land.

METHODS

We examined the geographic diffusion of three cholera outbreaks through their linkage with the wind direction: a) the progress of Vibrio cholerae O1 biotype El Tor in Africa during 1970-1971 and b) again in 2005-2006; and c) the rapid spread of Vibrio cholerae O139 over India during 1992-1993. We also discuss the possible influence of the wind direction on windborn dissemination by flying insects, which may serve as vectors.

RESULTS

Analysis of air pressure data at sea level and at several altitudes over Africa, India, and Bangladesh show a correspondence between the dominant wind direction and the intracontinental spread of cholera.

CONCLUSIONS

We explored the hypothesis that winds have assisted the progress of cholera Vibrios throughout continents. The current analysis supports the hypothesis that aeroplankton (the tiny life forms that float in the air and that may be caught and carried upward by the wind, landing far from their origin) carry the cholera bacteria from one body of water to an adjacent one. This finding may improve our understanding of how climatic factors are involved in the rapid distribution of new strains throughout a vast continental area. Awareness of the aerial transfer of Vibrio cholerae may assist health authorities by improving the prediction of the disease's geographic dissemination.

Epidemiological study of Q fever in humans, ruminant animals, and ticks in Cyprus using a geographical information system

A cross-sectional study of Q fever was conducted in a representative sample of the human and animal population in Cyprus in order to assess the seroprevalence of Q fever and the prevalence of related risk factors. A total of 583 human and 974 ruminant animal serum samples were collected and tested for the detection of antibodies against Coxiella burnetii phase II antigen using an indirect immunofluorescent assay. One hundred forty-one ticks were collected from the infested animals examined; the polymerase chain reaction and the shell-vial technique were used to detect and isolate C. burnetii. Standardized questionnaires were used to obtain information concerning inhabitants and their animals. A geographical information system was used to identify high-risk regions. The prevalence of IgG antibodies against C. burnetii phase II antigen was estimated at 52.7% for humans, 48.2% for goats, 18.9% for sheep, and 24% for bovines. C. burnetii was detected in 11 (7.8%) ticks. Using the geographical information system, two villages were identified as high-risk regions on the basis of high seroprevalence rates of IgG antibodies in humans and animals. Risk factors related to Q fever seropositivity were identified by logistic regression analysis and included age, residence, occupation, use of manure in the garden, ownership of animals (especially goats), and the presence of tick-infested or aborting animals. Q fever poses an occupational hazard to humans living in close contact with sheep and/or goats. In parallel, ticks should be considered an important aspect in the epidemiology of Q fever and should be further studied to better elucidate their role.

Clinicopathologic aspects of animal and zoonotic diseases of bioterrorism

We live in an era of emerging infectious diseases and the threat of bioterrorism. Most of the infectious agents of modern concern, from plague to avian influenza H5N1, are zoonotic diseases: infectious agents that reside in quiet animal reservoir cycles that are transmitted occasionally to humans. The public health, health care, and veterinary communities have an enormous challenge in the early recognition, reporting, treatment, and prevention of zoonotic diseases. An intimate understanding of the natural ecology, geographic distribution, clinical signs, lesions, and diagnosis of these diseases is essential for the early recognition and control of these diseases.

A pedagogical farm as a source of Q fever in a French city

Q fever is a worldwide zoonosis caused by Coxiella burnetii and presents as both acute or chronic cases. The disease can be transmitted from animal reservoirs to humans by inhalation of infected aerosols. A previous study had revealed a hyperendemic focus in South France. A case-control study was carried-out in this area from 1996 to 1999. Besides the role of wind, this study stressed out the exposure to a pedagogical farm as an independent risk factor (4.7% of cases - 0 controls): Exposure to sheep and new-born animals (OR: 3.07 and 4.01 respectively) were not significant after omission of people exposed to the pedagogical farm. Such farms are visited by people who would not have any other contact with farm animals. These farms require a drastic hygiene and control. Q fever, as a public health problem, still requires further studies to identify and confirm individual behavioral risk factors.

Questing one Brazilian query: reporting 16 cases of Q fever from Minas Gerais, Brazil

Q fever has been considered non-existing in Brazil where reports of clinical cases still cannot be found. This case-series of 16 patients is a result of a systematic search for such illness by means of clinical and serologic criteria. Serologic testing was performed by the indirect microimmunofluorescence technique using phase I/II C. burnetii antigens. Influenza-like syndrome was the most frequent clinical form (eight cases - 50%), followed by pneumonia, FUO (fever of unknown origin), mono-like syndrome (two cases - 12.5% each), lymphadenitis (one case - 6.3%) and spondylodiscitis associated with osteomyelitis (one case - 6.3%). The ages varied from four to 67 years old with a median of 43.5. All but one patient had positive serologic tests for phase II IgG whether or not associated with IgM positivity compatible with acute infection. One patient had both phase I and phase II IgG antibodies compatible with chronic Q fever. Seroconvertion was detected in 10 patients. Despite the known limitations of serologic diagnosis, the cases here reported should encourage Brazilian doctors to include Q fever as an indigenous cause of febrile illness.

Wind, rain and bacteria: The effect of weather on the microbial composition of roof-harvested rainwater

The microbiological and chemical quality of tank-stored rainwater is impacted directly by roof catchment and subsequent run-off contamination, via direct depositions by birds and small mammals, decay of accumulated organic debris, and atmospheric deposition of airborne micro-organisms and chemical pollutants. Previous literature reports on roof water quality have given little consideration to the relative significance of airborne micro-organisms. This study involved analyses of direct roof run-off at an urban housing development in Newcastle, on the east coast of Australia. A total of 77 samples were collected during 11 separate rainfall events, and microbial counts and mean concentrations of several ionic contaminants were matched to climatic data corresponding to each of the monitored events. Conditions both antecedent to, and those prevailing during each event, were examined to investigate the influence of certain meteorological parameters on the bacterial composition of the roof water and indirectly assess the relative contribution of airborne micro-organisms to the total bacterial load. Results indicated that airborne micro-organisms represented a significant contribution to the bacterial load of roof water at this site, and that the overall contaminant load was influenced by wind velocities, while the profile (composition) of the load varied with wind direction. The implications of these findings to the issues of tank water quality and health risk analysis, appropriate usage and system design are discussed.

Coxiella burnetii Infection

Coxiella burnetii is an obligate intracellular bacterium that causes a worldwide zoonosis, Q fever, and can be misused as a biological warfare agent. Infection in animals (coxiellosis) is mostly persistent. Infection in humans is often asymptomatic, but it can manifest as an acute disease (usually a self-limited flu-like illness, pneumonia, or hepatitis) or as a chronic form (mainly endocarditis, but also hepatitis and chronic fatigue syndrome). C. burnetii infection in pregnant women may result in abortions, premature deliveries, and stillbirths. Infection in nature is maintained and transmitted by ticks as the principal vector and reservoir. Cattle, sheep, and goats are the most important source of human infections. Humans contract C. burnetii infection mostly by aerosol in contact with contaminated environs, wind playing an important factor in spreading the infection. The wide distribution of C. burnetii contributes to a high resistance of its extracellular small cell variant to environmental conditions. Its intracellular large cell variant, adapted to survive under harsh conditions of phagolysosomes, enables long-term survival and persistence of C. burnetii, namely in monocytes/macrophages. Host factors such as underlying disease and cell-mediated immunity play a decisive role in the clinical expression of C. burnetii infection. Complete genome analysis of C. burnetii will certainly contribute to better understanding of the pathogenesis of C. burnetii infection and will improve Q fever diagnosis and immunoprophylaxis.