BACKGROUND. On 28 June 2005, numerous cases of febrile illness were reported among 322 students and employees of a boarding high school located in an urban area in central Israel. Subsequent investigation identified a large outbreak of Q fever which started 2 weeks earlier. We describe the investigation of this outbreak and its possible implications. METHODS. We conducted a case-control study to identify risk factors for Q fever disease. Environmental sampling was conducted to identify the source and the mode of transmission of Coxiella burnetii, the infectious agent. RESULTS. Of 303 individuals, 187 (62%) reported being ill between 15 June and 13 July 2005. Serological evidence for C. burnetii infection was evident in 144 (88%) of the 164 tested individuals. Being a student, dining regularly at the school dining room, and boarding at school during a June religious holiday and the preceding weekend were all significant risk factors for contracting Q fever. C. burnetii DNA was detected using polymerase chain reaction on samples from the school dining room's air conditioning system, supporting contribution of the air conditioning system to the aerosol transmission of the infectious agent. CONCLUSIONS. We report a large outbreak of Q fever in an urban school, possibly transmitted through an air conditioning system. A high level of suspicion for C. burnetii infection should be maintained when investigating point source outbreaks of influenza-like disease, especially outside the influenza season.

Abstract. A nested polymerase chain reaction (PCR) assay has been developed and used in the diagnosis of fatal and benign cases of Mediterranean spotted fever (MSF). The test was based on specific primers derived from a Rickettsia conorii 17-kD protein gene. A positive signal was obtained from spotted fever group (SFG) and typhus group (TG) rickettsiae. Discrimination between SFG and TG rickettsiae was based on a restriction fragment length polymorphism test. Other gram-negative bacterial species tested did not generate a signal, attesting for the specificity of the assay. The SFG-specific DNA fragment was detected in four of 29 acute-phase sera from serologically confirmed patients with MSF, while acute-phase sera from 25 patients without MSF were PCR negative. Acute-phase sera samples (five of five) and tissue autopsies (six of seven) from fatal suspected cases of MSF were PCR positive. The results demonstrate that sera and tissue samples are suitable specimens for the nested PCR tests, especially in fatal cases.

The worldwide epidemiology and population-based incidence of Q fever endocarditis (QFE) have been less well studied than those for uncomplicated Q fever. An exhaustive literature review revealed 408 patients with QFE reported between 1949 and 1994, mostly from 3 large geographic areas. Underlying valvular heart disease was almost invariably present, and 38% had prosthetic valves. The most common clinical manifestations were fever and congestive heart failure. The mortality rate dropped over the years from 65% to 25%, but a meta-analysis of published data showed the death rate to be significantly lower among patients receiving combination therapy (12/65, 18%), as compared to patients treated with tetracycline alone (18/41, 44%, p = 0.005). A 10-year (1983-1992) retrospective nationwide survey of QFE in Israel revealed 35 patients with QFE, representing an annual incidence of 0.75 cases per 1 million population. Underlying heart disease, clinical manifestations and outcome in the Israeli group were not substantially different from those described in the world literature. The current state-of-the-art clinical approach includes early diagnosis, prompt initiation of combination therapy for at least 3 years, and long-term clinical and serologic follow-up. Adherence to these rules might have contributed to the improved prognosis in recent years.

Chronic Q fever has been associated with endocarditis, granulomatous hepatitis, and osteomyelitis but only rarely with pregnancy. The apparent predilection of Coxiella burnetii, the organism causing Q fever, for the human placenta suggests that chronic Q fever of pregnancy is due to placentitis. We describe a patient with chronic, clinically apparent Q fever in pregnancy and a successful outcome. The diagnosis was made both by serology and by isolation of C. burnetii from the patient's serum and placenta. Therapy with erythromycin and rifampin contributed to the delivery of a healthy baby. The mother's infection was clinically cured by subsequent therapy with doxycycline and rifampin.

Physicians often encounter patients who present with a vague clinical syndrome. A wide serological workup is often ordered, which may include tests for Coxiella burnetii in endemic areas. Often, the results of these tests pose new dilemma, with overlapping positive laboratory assays. The objective of this investigation was to characterise the serological overlap between acute Q fever and other infectious and immunological diseases. We retrospectively scanned the files of patients with a positive or equivocal immunoglobulin (Ig) M for C. burnetii phase II over a period of 8 years in a general hospital. Clinical and laboratory data, including antibodies to infectious agents and antibodies related to immunological states, were recorded. Anti-nuclear antibody (ANA), smooth muscle antibody (SMA) and rheumatoid factor were positive in 38%, 33.3% and 22.2% of the cases, respectively. In patients with acute Q fever, elevated IgM levels for Epstein-Barr Virus (EBV), cytomegalovirus (CMV), Mycoplasma pneumoniae, parvovirus, Bordetella pertussis, Rickettsia conorii and R. typhi were noted in 13.8%, 8.3%, 12.12%, 22.2%, 25%, 13% and 21.7% of cases, respectively. Acute Q fever induces a non-specific immunological arousal in a significant number of patients. This may interfere with diagnosis and delay treatment. Caution, clinical judgment and serological follow-up is warranted in such conditions.