Roentgen Manifestations of Q Fever

Abstract

Q fever has been found to exist among the general population in and around Los Angeles, where a survey by the United States Public Health Service has shown it to be endemic (1, 18). Over 300 cases have been recognized in Southern California since the disease was first suspected in this region by Young (24) in May 1947. Slightly less than half of the patients were hospitalized during the acute phase of their illness, affording the authors an opportunity to study the roentgen manifestations. This report is based on a survey of the roentgenograms of the chest of 77 patients, selected on the basis of availability and completeness of records. Thirty-nine of this group were admitted to the Los Angeles County Hospital, the remainder to various other hospitals in the area. Historical Q fever was first described by Derrick (8) in Australia in 1937 following an outbreak of an obscure febrile illness among packing house workers. The rickettsia which was isolated was proved to be the causative organism of the diseases known as “nine-mile fever” in Montana and “Balkan grippe” in Southern Europe, as well as the “Q fever” of Australia. Outbreaks of Q fever occurred among Allied troops in the Mediterranean Area in 1944 and 1945 (22) and among troops returning to this country from that region (12). Q fever has also been reported from Panama (4) and Switzerland (13). The first known naturally occurring outbreaks of Q fever in the United States took place in Amarillo, Texas, in March 1946, with 55 cases, including two deaths (17). A second outbreak of 36 cases occurred in Chicago in August 1946 (23). Both of these epidemics were explosive in onset, of short duration, and limited to persons handling cattle and sheep en route to or during slaughter. Lennette and Meiklejohn (19) reported two outbreaks of Q fever in Central and Northern California occurring between February and May 1948, with a total of more than 100 cases. In most cases there was a history of close contact with livestock, but in some no such history was obtainable. Etiology The causative agent of Q fever is a rickettsia which was first isolated by Burnet (3) in Australia and Davis and Cox (6) in the United States. The organism, Coxiella burnetii (Derrick) is a minute Gram-negative rod which is resistant to drying, chemicals, and heat (16). It passes through Berkefe1d filters. It may be recovered from the blood stream of patients with Q fever and has been found in most of the organs at autopsy (2). Epidemiology The organism has its chief reservoir in cattle and has been found in more than half of the unpasteurized milk specimens tested in Los Angeles County (15). There is no person-to-person transmission of the disease. The incidence is highest among meat packers, laboratory workers studying Coxiella burnetii, and those working in or living near dairies. Nearly one-third of the patients in Los Angeles County denied any exposure to cattle or unpasteurized milk.