Detection of human blood in the bat tick Carios (Ornithodoros) kelleyi (Acari: Argasidae) in Iowa.

The argasid tick Carios (Ornithodoros) kelleyi Cooley & Kohls is a common ectoparasite of bats and has been found in massive numbers in homes with associated bat colonies in eastern Iowa. This tick feeds nearly exclusively on bats in nature. Several inhabitants of infested homes complained of "bug bites" at night while asleep that may have resulted in erythematous, edematous, urticaric skin lesions and constitutional signs and symptoms. We provide laboratory evidence that a single, engorged C. kelleyi nymph contained host blood from a human female. The clinical implications of our findings are intriguing but unclear.

Sporadic Legionnaires' disease: clinical observations on 87 nosocomial and community-acquired cases.

To add information about sporadic Legionnaires' disease, 87 cases of L. pneumophila pneumonia were reviewed. Twenty cases were nosocomial infections and 67 cases were community-acquired. Most cases (64%) occurred between July and October. The mean age of patients was 51.4 years and males outnumbered females 2.5:1.0. Thirty-one percent of patients were receiving corticosteroid, immunosuppressive, or antineoplastic chemotherapy when illness began. Immunosuppression at onset of illness was more common in nosocomial infections (90%) than in community-acquired infections (14%). Seventy percent of patients had underlying diseases. Malignancies, renal failure, and transplantation were the most common conditions underlying nosocomial infections. Chronic lung disease and malignancies were the most common diseases underlying community-acquired infections. The case-fatality rate in nosocomial infection (70%) was greater than that in community-acquired disease (22%). Clinical, laboratory, and radiologic features of the cases were examined. Illness ranged from mild to severe. Extrapulmonary findings of encephalopathy and renal failure were more common in fatal than in non-fatal cases. Indirect immunofluorescent and microagglutination antibody responses plateaued by the fourth week of illness. Twenty-nine patients died. The case-fatality rate of patients receiving erythromycin (6%) was less than that of patients receiving penicillin (36%), ampicillin (28%), cephalosporin (32%), or aminoglycosides (41%). Despite erythromycin therapy, the case fatality rate for nosocomial L. pneumophilia pneumonia was unacceptably high (25%).

Legionnaires' disease among pneumonias in Iowa (FY 1972-1978) II. Epidemiologic and clinical features of 30 sporadic cases of L. pneumophila infection.

We reviewed retrospectively the clinical records of 30 cases of sporadic Legionella pneumophila infection that occurred in Iowa between FY 1972 and 1978. Cases occurred throughout the year, most between May and December. Twenty-one male patients and 9 female patients ranging in age from 5-80 years were infected. Half the patients smoked or had an underlying illness; five were receiving corticosteroids or immunosuppressive therapy. Occupations and exposures related to hospitals, construction and travel were common; four patients had been exposed to birds. In addition to L. pneumophila infection, six patients had evidence of infection with a viral, mycoplasmal, bacterial, mycobacterial or fungal pathogen; three had had preceding dental infections. Twenty-seven cases were pneumonias visible on radiographs. Fever, cough, chills, myalgia and rales occurred inover half the cases. Headache, gastrointestinal symptoms and encephalopathy also were seen. Upper respiratory symptoms were uncommon. Urinalysis and blood studies often suggested renal and hepatic involvement, but other routine laboratory diagnostic tests were not helpful. All but two patients were hospitalized; seven required intensive care. The median duration of hospitalization was 12 days. Two patients who did not receive erythromycin or tetracycline therapy died.

Background prevalence of microagglutination antibodies to Legionella pneumophila serogroups 1, 2, 3, and 4.

The background prevalence of microagglutination antibodies to Legionella pneumophila was determined by testing the sera of 517 individuals who lived or worked in a small Iowa town. In this population, the upper limit of normal microagglutination titer for serogroups 1, 3, and 4 was 1:16, and that for serogroup 2 was 1:8. The prevalence of microagglutination titers of greater than or equal to 1:32 against any serogroup of L. pneumophila was only 7.4% and did not vary significantly with age or sex.

Indirect immunofluorescence antibodies to Legionella pneumophila: frequency in a rural community.

The background prevalence of indirect immunofluorescence antibody to Legionella pneumophila in a rural community was determined by testing sera from 517 volunteers. The upper limit of normal antibody titer was found to be 1:64 with L. pneumophila serogroup 1 (Philadelphia 1) used as antigen. High titers (greater than or equal to 1:128) were found in 13.2% of the sera and occurred with similar frequencies in males and females. In individuals 40 years of age and older, however, high titers were 2.7 times as prevalent in males as females.

Comparative features of pneumococcal, mycoplasmal, and Legionnaires' disease pneumonias.

Retrospectively, we clinically compared community-acquired cases of Legionnaires' disease, pneumococcal, and mycoplasmal pneumonias. Relative to pneumococcal and mycoplasmal pneumonias, patients with Legionnaires' disease were significantly more likely to present with unexplained encephalopathy, hematuria, and elevation of serum glutamic-oxalacetic transaminase than were those with pneumococcal and mycoplasmal pneumonias. We found upper respiratory symptoms infrequently in patients with Legionnaires' disease, and progression of pulmonary infiltrates occurred commonly. Differentiation of Legionnaires' disease pneumonia without encephalopathy from pneumococcal and mycoplasmal pneumonias may be difficult because of demographic, clinical, laboratory, and radiographic similarities.

Legionnaires' disease in pneumonia patients in Iowa. A retrospective seroepidemiologic study, 1972-1977.

The frequency of Legionnaires' disease among 586 cases of pneumonia that occurred in Iowa between fiscal years 1972 and 1977 was studied retrospectively on the basis of paired sera. The frequency of confirmed Legionnaires' disease was 4.1% and of presumptive Legionnaires' disease was 11.4%. Infections with the Legionnaires' disease (LD) bacterium were most frequent in the summer. Of the 22% of pneumonias for which a cause could be defined, Legionnaires' disease was third in frequency behind Mycoplasma pneumoniae and influenza A virus infections. Infections with the LD bacterium occurred in association with pneumonias in most age groups. The youngest patient with LD infection was a 5-year-old boy with pneumonia. The disease occurred 3.2 times more often in males than in females. In males, the frequency of confirmed and presumptive Legionnaires' disease increased steadily to plateau after the fourth decade at about 12% and 28%, respectively. In females the frequency of presumptive Legionnaires' disease was 7% to 16%, relatively evenly distributed over all age groups. Pneumonias associated with LD bacterium infection should be considered in the differential diagnosis of community-acquired pneumonias in most age groups.

Haemophilus influenzae Type D meningitis.

This report describes an unusual pathogen associated with post-traumatic meningitis. Haemophilus influenzae type D was isolated from both cerebrospinal fluid and blood of this patient with meningitis.

Inhibition of the steroidogenic effects of cholera and heat-labile Escherichia coli enterotoxins by GM1 ganglioside: evidence for a similar receptor site for the two toxins.

The effects of three different ganglioside preparations on cholera enterotoxin (CT) and heat-labile Escherichia coli enterotoxin (ECT)-induced steroidogenesis in Y1 and OS3 adrenal tumor cells in tissue culture were examined. Only with GM1 ganglioside was any inhibition of the toxins' effects noted. Concentrations of the crude ECT preparation that gave similar morphogenic and steroidogenic effects as CT were inhibited by the same amount or less of GM1 as that required to inhibit the effects of CT. The results of competition experiments also demonstrated that previous incubation of GM1 with one toxin could inhibit the ganglioside's ability to inactivate the other toxin. These findings indicate that at least for Y1 and OS3 adrenal tumor cells, GM1 may resemble or be the receptor for both CT and ECT.