The geographic conundrum of infections: where or wherefore?
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Biomedical subjects
Publications and source records attributed to D W Fraser.
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Retrospective study shows that a 1957 outbreak of pneumonia in Austin, Minnesota, was Legionnaires' disease. Between June 7 and August 9, 1957, 78 persons were hospitalized with acute respiratory disease of unknown cause. Most had fever, headache, cough, and pneumonitis; two died. Ages ranged from 14-83 years; half of the patients were aged 55 years or older. Eighty-seven per cent were men. There were no secondary cases. Forty-six (59%) of the 78 patients were employees at a local meat packing plant, in distinction to the area's total working population (32%). Serosurvey of 15 of the 1957 outbreak cases and 30 controls matched for age, sex, and either occupation or residence was carried out in 1979. Antibody titers were determined for Legionella pneumophila serogroups 1-4 by means of indirect immunofluorescence. Twelve (80%) of the 15 cases and 13 (43%) of the 30 controls had antibody titers of 1:64 or greater to one or more of the L. pneumophila serogroups. Significant differences in L. pneumophila antibody titers (prevalence and level) were found between cases and control groups matched for residence (serogroups 1-3) or occupation (serogroups 2 and 3). Only three of 20 Austin residents with pneumonia diagnosed between 1978 and 1980 had L. pneumophila antibody titers of 1:128 or greater (p less than 0.001), in comparison to cases. These serologic data and the 1957 clinical and epidemiologic observations support the contention that this is the earliest documented outbreak of Legionnaires' disease.
In January 1980, an outbreak of 138 cases of acute pulmonary disease occurred among employees of a Michigan limestone quarry. The source of exposure was a vessel repair building (relative risk = 5.8) and the time of exposure was January 10 (relative risk = 2.4). Work activities associated with the specific place and time suggested exposure to a pulley which had been stored in a ring-billed gull nesting area as the cause of illness. Histoplasma capsulatum was recovered from the nesting area, the pulley, and the sputum of several patients. Early serologic testing confirmed the diagnosis of acute pulmonary histoplasmosis.
An exact probability test and its asymptotic version are described for testing the hypothesis that clustering of disease observed among population units is likely to have been due to chance alone. The test is based on a scheme for ranking possible arrangements of ill and well persons by degree of clustering, as measured by the sum, over all population units, of the ratio of the number of case pairs in a unit to the size of the unit. The proposed measure of clustering is attractive because increasing segregation of ill and well persons consistently results in a higher index of clustering. The power of the test seems at least as good as that of methods with less attractive clustering measures. The exact version allows analysis of clustering in a small number of population units, while the asymptotic version permits calculations based on larger samples.
Group C meningococci were isolated during an epidemic of meningococcal meningitis which occurred between January and May 1979 in eastern Upper Volta, an area previously associated with endemic and epidemic group A disease. A total of 539 cases of meningitis, 55 of which were fatal, were reported, giving an attack rate of 517 cases per 100 000 inhabitants. Attack rates were higher for children under 15 years of age. Clinical and bacteriological data suggested that the group C meningococci were sulfonamide-resistant. The last meningococcal epidemic in Upper Volta occurred in 1970 and was nationwide. Epidemic cycles of group A meningococcal meningitis have occurred at 10-15 year intervals in the sub-Saharan region, raising concern that the current increase in activity may presage more wide-spread disease in the next dry season.
Two outbreaks of peritonitis caused by a Mycobacterium chelonei-like organism--a previously unrecognized pathogen--occurred among patients receiving intermittent chronic peritoneal dialysis (CPD). In one center, five of 22 patients who had undergone CPD during a one-month period developed peritonitis caused by an M. chelonei-like organism acquired from a single contaminated automated CPD machine. In a second center, five of eight patients who had received CPD during a several-week period became infected, apparently as a result of cross-infection from contaminated machines. Seven sporadic cases of peritonitis due to an M. chelonei-like organism were also found. M. chelonei-like organisms can survive and proliferate in water and are relatively resistant to formaldehyde. Defects in the design of CPD machines and disinfection procedures were identified that may have permitted M. chelonei-like organisms to survive attempted disinfection.
An outbreak of pharyngitis associated with beta-hemolytic streptococci of Lancefield group G occurred among persons who had attended a convention that was held June 21-24, 1979, in a Florida hotel. Seventy-two (31 per cent) of 231 interviewed conventioneers were ill. Group G streptococci were isolated from the throats of 10 (63 per cent) of 16 persons with pharyngitis and 1 (2 per cent) of 41 persons without pharyngitis (p less than 10(-5)). Antistreptolysin O titers in convalescent-phase serum samples from persons with pharyngitis were significantly higher than those from age-matched controls. Fifty-seven (51 per cent) of 111 conventioneers who had attended a convention luncheon developed pharyngitis compared with 12 (10 per cent) of 117 persons who did not (p less than 10(-9)). All persons who had attended the luncheon and had become ill had eaten a chicken salad served at the luncheon. Their median incubation period was two days. The cook who had prepared this chicken salad developed pharyngitis after the luncheon and had a throat culture positive for group G streptococci. No instances of rheumatic fever were identified and secondary illness in household contracts was rare. This outbreak indicates that group G streptococci can cause outbreaks of pharyngitis similar to those caused by group A streptococci and suggests that penicillin therapy and prophylaxis may not be needed.
A prospective study of spread of M-type 1, 2, 13, 14, 25 and 60 group A Streptococcus in 64 families in Qalyub, Egypt, in 1972-1974 showed that type-specific serum bactericidal antibody does not protect against pharyngeal acquisition of homologous organisms. The presence of type-specific antibody also does not appear to affect duration of carriage of the organism. Type-specific immunity must be mediated in another way, such as by local antibody or trough prevention of infection (as evidenced by a host response) following acquisition. This study also confirms the observations of others that administration of penicillin lowers the probability that a person who acquires group A Streptococcus will develop type-specific antibody.
The disinfection of cooling towers based on manufacturers' treatment protocols, as employed in units installed at various public gathering places in Dallas, Tex. (hotels, municipal auditorium), and at the city health department, was evaluated for effectiveness in controlling Legionella pneumophila and compared with previous laboratory studies. In specimens collected in September and December, 1978, L. pneumophila was isolated from 2 of 4 specimens from untreated cooling towers, 2 of 4 specimens from towers treated with agents deemed ineffective in earlier laboratory tests, 6 of 11 specimens from towers treated with putatively effective agents, and 0 of 4 specimens from towers treated with an agent unknown efficacy. These results suggest the need for further studies to identify biocidal agents effective in eliminating L. pneumophila from air-conditioning cooling towers.
Of an estimated 17632 participants of the 1979 Peachtree Road Race, a 10-km race held at 0800 on 4 July in Atlanta, Georgia, 29 had severe heat injury (collapse with altered mental status and rectal temperature of 39.7 degrees C or greater); all 29 recovered promptly. The temperature was 24.0 degrees C; the relative humidity, 83%; and the wet bulb-globe index, 23.0 degrees C. Compared with unaffected participants matched by age, sex, and predicted finishing time, case-runners were taller, had slower best recent 1.6-km and 10-km times, had run less in June, were more likely to achieve 89% of estimated maximum aerobic capacity during the race, less often splashed with water, were more likely to have underestimated their predicted finishing times based on their best recent 10-km times, and were more likely to live in Georgia. Height, sprinkler use, and underestimating predicted finishing times were each significant in the presence of the others. These observations suggest that participants of similar races, particularly those taller than 179.2 cm, should splash with water at least twice and base their predicted finishing times on their best recent 10-km times; adherence to these recommendations by runners at risk should reduce their severe heat injury risk at least 8.1 times.
Between June 18 and July 9, 1979, Legionnaires' disease (LD) developed in 13 persons who had visited a hotel complex in Wisconsin. All had visited the part of the hotel that contains the restaurants and meeting rooms (building A). Legionnaires' disease occurred in 1% who had been exclusively in the meeting rooms and in 0.1% who had eaten only at the hotel restaurants. Furthermore, 1.5% exposed to meeting room 1 and none of those exposed only to the other meeting rooms had LD. Legionella pneumophila was isolated from water in the cooling tower on top of building A. Located within 5 m downwind of the cooling-tower exhaust, a chimney with an open damper allowed cooling-tower exhaust (as demonstrated by air tracer studies) to enter meeting room 1 via the fireplace. Although cases did not occur after the cooling-tower water was treated by continuous hyperchlorination and the chimney was sealed, a seven-day lag occurred between treatment and elimination of the organism from the tower water.
During 1971-77 the incidence of bacterial meningitis among Alaskan Eskimos was 84.4 cases per 100 000 population per year, which is more than 10 times that for most other U.S. populations. Haemophilus influenzae (HI) accounted for 68% of meningitis cases. The average annual incidence of HI disease per 100 000 children below 5 years of age was 409 for patients with meningitis only and 491 for patients with all systemic HI disease. Children with HI meningitis in Alaska tended to be younger than those in other U.S. populations, 98% of the children affected being less than 18 months of age. The risk for all HI disease was 2.4% during the first year of life. The spectrum of HI disease in Alaska differs from that in other populations in that no patient had epiglottitis and 5% of children had recurrent HI disease. Alaskan newborns and children over 4 years old had HI anticapsular antibody titres that were nearly thrice those for children of similar ages in other U.S. populations (p less than 0.005). The pharyngeal carriage of HI type b (5%) and the rectal carriage of Escherichia coli K100 (2%), an organism with a capsule antigenically similar to HI type b, did not differ from those in other populations. The high incidence of disease almost exclusively in the very young and the early development of antibody in this population suggest that the high rate of disease is due to early exposure to HI type b rather than to an unusual susceptibility to HI type b.
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As of April 30, 1980, 83 nosocomial cases of sporadic legionellosis had been reported to the Centers for Disease Control (CDC). In all 83 cases the patients had pneumonia; the median age of the patients was 56.5 years. All but one patient were hospitalized at the time of onset. Of 71 patients for whom the outcome is known, 22 (31 percent) died of causes directly attributed to their infection. Eleven patients had end-stage renal disease, 28 were receiving systemic immunosuppressive medications, 17 had cancer, 12 had chronic bronchitis or emphysema, 29 were smokers, and four had diabetes mellitus. Risks of acquiring nosocomial sporadic legionellosis for patients with these conditions relative to the general United States population = 340, 26, 11, 3.7, 1.9 and 1.3, respectively. These risk factors are similar to those identified for sporadic community-acquired legionellosis and for epidemic nosocomial legionellosis. Methods for preventing nosocomial legionellosis are not known, but comparing Legionella to other water-associated organisms which have been spread from medical devices to cause pneumonia may be fruitful.
Bacteria recently recognized as nosocomial pathogens generally fall into three categories: those that grow slowly, those that are fastidious in their nutritional or atmospheric requirements and those that resemble commensals. Each characteristic has contributed to the delay in perceiving their importance. Mycobacterium chelonei and Myco. fortuitum--which grow slowly, although characterized as "rapid-growing" mycobacteria--cause sternal osteomyelitis, pericarditis and endocarditis after cardiac surgery as well as other wound infections after many types of surgery. Myco. chelonei-like organisms have been found to cause "sterile" peritonitis in patients receiving long-term peritoneal dialysis. Legionella pneumophila and L. micdadei are fastidious bacteria that were more difficult to detect because they stain poorly with the Gram method. They cause pneumonia and lung abscess, especially in immunocompromised people. Clostridium difficile is an anaerobe that causes toxin-mediated pseudomembranous colitis in persons given antibiotics that inhibit competing gut bacteria. Chylamydia trachomatis, an intracellular organism that has not been grown in vitro, causes pneumonia and conjunctivitis in young infants who acquire the organism from their mothers at birth. Group JK bacteria cause septicemia in patients whose immune responses have been suppressed and must be distinguished from "diphtheroid" contaminants in blood cultures. Clinicians, microbiologists and epidemiologists must be alert to the characteristics of these organisms that make them easily overlooked and should also anticipate the existence of other bacteria not yet identified.
In the period April to October, 1977, an epidemic of pertussis in the outpatient population of a large metropolitan hospital involved 115 cases that were diagnosed by culture or direct fluorescent antibody tests. A study of secondary cases in household contacts showed attack rates of 81% in children under one year of age; attack rates decreased with increasing age to 8% in persons over 20 years of age. Vaccine efficacy was estimated to be 63%. There was no evidence of decreased efficacy with increasing time after vaccination. Fourteen asymptomatic FA-positive individuals were identified; four of these were also culture positive. Four were adults and ten were children. Nine of the ten children had received three or more vaccinations, compared to only 29 of 78 symptomatic children (P = 0.002).
To learn the role of Legionella pneumophila, the agent of Legionnaires' disease, in childhood illness, a prospective study was conducted among 52 children younger than four years of age with acute disease of the lower respiratory tract. Viral, mycoplasmal, and bacterial cultures and acute- and convalescent-phase sera were obtained during 64 episodes of acute illness; additional sera were drawn annually for three to five years. On the basis of serologic evidence, none of the acute episodes appeared to be due to L. pneumophila serogroup 1 or 2. However, examination of annual serum specimens showed that 27 (52%) of the children had rises in titer of indirect immunofluorescent antibody (a fourfold or greater rise to a reciprocal titer of greater than or equal to 128). Most rises in titer were in response to the serogroup 2 antigen. These results suggest that L. pneumophila is not a common cause of acute respiratory disease in early childhood in the study area but that children are frequently exposed to the organism. Alternatively, the serologic responses might be to unrelated cross-reacting microorganisms.