35
EPIDEMIOLOGY Outbreak of Pontiac fever due to Legionella anisa
An outbreak of Pontiac fever occurred among 34 of 56 people attending conferences at a hotel in Santa Clara County, California, in 1988. Two groups had an acute febrile upper respiratory illness, with a mean attack rate of 82% and a mean incubation period of 56 hours. Symptoms resolved spontaneously within 5 days. Legionella anisa, which had not previously been associated with outbreaks of Pontiac fever or legionnaires’ disease, was isolated from a decorative fountain in the hotel lobby. In addition, 5 of 8 pairs of serum samples from cases showed a more than fourfold rise in antibody titre to the L anisa recovered from the fountain. 42% of hotel employees had titres ≥256 against L anisa, whereas none of 48 serum samples from matched controls had titres ≥128. The findings raise concern about water treatment protocols for extent of disease that might be caused by exposure to aerosols containing L anisa and other Legionella
species.
Before the outbreak there was no set schedule for cleaning the fountain. The fountain used recirculated water, and cleaning consisted of draining the pool, mopping the tile with hot water, polishing the marble top, and running hot water through the nozzles and jets of the fountain. No disinfecting chemicals were used. Here we report the association of Pontiac fever due to a newly recognised pathogen, L anisa, with a decorative fountain.
Methods
Epidemiology Initial information
was
obtained from
cases
by telephone
8-10
days after exposure. A questionnaire was then developed and sent to all 56 persons attending the conferences. They were asked about specific activities at the hotel, symptoms, time of onset, baseline health status, smoking history, and secondary illness among contacts. A case was defined as illness with fever or chills and either (1) cough or dry sore throat or (2) headache or muscle aches.
Serology Introduction
On April 20 and 22, 1988, two day-long conferences were held at a hotel in Santa Clara County, California. Both meetings were conducted in the same conference room on the ground floor, near the lobby. Both groups of conference participants were served breakfast and lunch at tables arranged around a decorative fountain in the lobby. The Santa Clara County Health Department was first notified of an outbreak of an influenza-like illness on April 28. The people affected suspected that the illness was food-related because several of them also had abdominal cramps. No hotel employee reported a similar illness. There was no previous record of illness from this establishment. The hotel is situated in a suburban area of the San Francisco peninsula. The structure is 4 years old, with three floors of rooms built around a central roofed atrium serving as a lobby, in the centre of which is a decorative fountain. The fountain is spherical and emits a fine aerosol. Within 100 feet of the lobby is an outdoor swimming pool and spa. The activities of both groups of conference participants were confined to the ground floor and an underground parking area. The hotel is served by the municipal water supply. The hotel is heated and cooled by a waterless heat exchange unit.
Paired serum samples were obtained from 5 members of one group and from 3 of the other. The acute samples were obtained approximately Iweeks after onset and the convalescent sera 4
weeks later. The sera were tested for antibody against influenza A and B, parainfluenza, and respiratory syncytial virus (RSV). In view of the high attack rate, short incubation period, and typical symptoms, the possibility of Pontiac fever was raised at the outset; therefore, the same samples were also tested for antibody to Legionella pneumophila. Serum was also tested at the Centers for Disease Control (CDC) for L feeleii, another causative agent of Pontiac fever. Upon recovery of Legionella anisa from the fountain water, CDC was requested to test those paired samples for seroconversion to L anisa as well. In addition, antibody prevalence to L anisa was studied among 24 hotel workers who provided specimens, and their antibody status was contrasted with that of 48 healthy controls who had undergone premarital blood tests at the county health department. The controls were matched to hotel workers by age, sex, and ethnic group. ADDRESSES: Santa Clara County Health Department, San Jose, California (M. D Fenstersheib, MD, M. Miller, MD, C. Diggins, PHN, S. Liska, DrPH, L. Detwiler, BS); California Department of Health Services, Berkeley, California (S. B Werner, MD, D Lindquist, MPH), and Division of Bacterial Diseases, Center for Infectious Diseases, Centers for Disease Control, Atlanta, Georgia, USA (W. L. Thacker, MS, R. F Benson, MS). Correspondence to Dr M. D. Fenstersheib, Santa Clara County Health Department, 2220 Moorpark Avenue, San Jose, California 95128, USA.
36
CLINICAL FEATURES
feeleii. Water samples from the fountain paired samples showed a greater than fourfold rise in titre to L anisa; 4 pairs were from group A
pneumophila,
or
grew anisa. 5 of 8
and the other from group B. 10 (42%) of 24 hotel employees had antibody titres of 256 to L anisa. A raised titre from 6 other hotel workers gave titres of 128. By contrast, none of 48 control samples had titres of >_ 128 to L anisa. A raised titre correlated with length of employment at the hotel (p 0-028, by Fisher’s exact test) but not with age, sex, ethnic group, or time spent in the hotel lobby. =
Discussion were some differences between the two groups in clinical features. Onset of illness was more abrupt in group A (range = 52-86 h) than in group B (20-76 h), but in both groups incubation periods were compatible with Pontiac fever, which commonly has an incubation period of 24-48 h.1 The attack rate was higher in group A than in group B. Possible reasons for this discrepancy are reporting bias, differences in the degree or length of exposure to the fountain, inconsistency of air circulating factors between the two days, or differences in immunity between the two groups (eg, group A was younger and possibly more
There
*p = < U5 (x’) between the two groups.
susceptible).
Water sampling
heating and cooling units of the hotel were examined and standing water in the system was searched for. No standing water was found on the roof or in the duct system 10 days after the The
conference. Water from the fountain was tested but not that from the swimming pool since conference attendants had not had access to the pool.
The water in the fountain was never disinfected and this permitted contamination by L anisa and its persistence. Transmission of infection was probably via aerosols of the fountain water. After the outbreak, disinfection procedures were
instituted.
The clinical presentation was that of an influenza-like illness with an extraordinarily high attack rate, brief incubation period, and absence of secondary spread. The attack rate was higher among those attending the conference on April 20 (group A, 94%, 17/18) than among those attending on April 22 (group B, 71%, 17/24), but this difference was not significant. Group A was youner (median age of 36 years) than group B (median age 46). Few reported conditions that could predispose to illness, such as current smoking (3), chronic lung disease (1), use of corticosteroids (1), immunodeficiency (0), or history of splenectomy (1). None of the respondents had used the swimming pool or the spa. All had eaten near the fountain. First exposure for both groups was judged to be 8 am on the day of the respective seminars. The median incubation periods were 58 h for group A and 54 h for group B (table). The median duration of illness for each group was 2 days, with a range of 2-6 days for group A and 1-8 days for group B. Symptoms reported by 80% or more of both groups included headache, muscle ache, chills, fever, and malaise. A greater proportion of group A reported cough and chest pain than was the case in group B (X2, p < 005). There was no secondary spread within households. 9 persons sought medical care. No one was admitted to hospital and all recovered uneventfully.
This investigation showed that Legionella anisa can cause outbreaks of human disease. It was recovered from the suspect source (the decorative fountain), greater than fourfold antibody titre rises were found in cases, and high antibody levels to L anisa were prevalent among hotel workers but absent in healthy controls. Pontiac fever has been associated with four species of Legionella and is characterised by a sudden onset of fever, headache, myalgias, cough, and general debility. It does not progress to pneumonia nor is it contagious. No deaths have been reported and convalescence is generally complete and uneventful.2 Only pneumophila serogroups 1 and 6, L feeleii serogroup 1, and L micdadei have previously been linked to seven outbreaks of Pontiac fever.3-5 Though it was not known to be pathogenic at the time, L anisa has been isolated from potable hospital water in both Chicago and Los Angeles, and from an industrial cooling tower in New York. It was not until 1989 that L anisa was reported to be a pathogen. It was recovered from the bronchial lavage specimen of an immunocompromised patient with pneumoniaand in France from the pleural fluid of another immunocompromised individual with cancer.s With the increasing use of decorative fountains in enclosed spaces, such as shopping malls and hotels, possible transmission of the agents causing both legionnaires’ disease and Pontiac fever by aerosol exposure must be considered. All such fountains using recirculated water should be maintained and disinfected to prevent future cases and outbreaks of legionellosis.
Serology/water sampling The 8 paired samples of serum showed no rise in titres to influenza A or B, parainfluenza, RSV, Legionalla
We thank Barbara Sullivan, PHN, formerly of the Santa Clara County Health Department; Louise Ottis of the Division of Environmental Health, Santa Clara County Health Department; and Leon Alevantis and Janet Macher of the Air and Industrial Hygiene Laboratory of the California Department of Health Services.
Results
Epidemiology
37
REFERENCES
5.
Department of Health Services. Control of Communicable Diseases in California, 1983: 245-47. 2. Dave GS, Winn WC Jr. Legionnaires’ disease: respiratory infections caused by Legionella bacteria. Clin Chest Med 1987; 8: 419-48. 3. McDade JE, Shepard CC, Fraser DW, et al. Legionnaires’ disease: isolation of a bacterium and demonstration of its role in our respiratory 1. California
disease. N Engl J Med 1977; 297: 1197-203. 4. Broome CV. Current issues of epidemiology in legionellosis. In: Thornsberry C, Balows A, Feeley JC, Jakubowski W, ed. Legionella, Proceedings of the 2nd International Symposium. Washington DC: American Society for Microbiology, 1984: 205-09.
Wrench JG, Collier PW, et al. outbreak in non-pneumonic legionellosis due to Lancet 1989; i: 316-18.
Goldberg DJ,
Lochgoilhead fever Legionella micdadei.
GW, Feeley JC, Steigerwalt A, et al. Legionella anisa: a new species of Legionella isolated from potable waters and a cooling tower. Appl Environ Microbiol 1985; 49: 305-09. 7. Thacker WL, Benson RF, Hawes L, Mayberry WR, Brenner DJ. Characterization of a Legionella anisa strain isolated from a patient with pneumonia. J Clin Microbiol 1990; 28: 122-23. 8. Bornstein N, Mercatello A, Marmet D, Surgot M, Deveaux Y, Fleurette J. Pleural infection caused by Legionella anisa. J Clin Microbiol 1989; 6. Gorman
27: 2100-101.
VIEWPOINT Effect of low saturated fat diet in early and late cases of multiple sclerosis ROY LAVER SWANK
144 multiple sclerosis patients took a low-fat diet for 34 years. For each of three categories of
neurological disability (minimum, moderate, severe) patients who adhered to the prescribed diet (≤20 g fat/day) showed significantly less deterioration and much lower death rates than did those who consumed more fat than prescribed (>20 g fat/day). The greatest benefit was seen in those with minimum disability at the start of the trial; in this group, when those who died from non-MS diseases were excluded from the analysis, 95% survived and remained physically active.
Introduction
suggestion, made in 1950, that the frequency of multiple sclerosis (MS) was related to fat consumption1 was based on the relative frequencies of multiple sclerosis (MS) and the calculated fat consumption of different populations, and it was later supported by a Norwegian study of the incidence of MS and nutrition,2by analysis of similar data from many geographical areas,3and by clinical studies.4-8 One study, in which patients were followed up for 34 years, implicated saturated animal fats- the lowest saturated fat consumers (20 g/d; mean 17 g/d) showed little worsening of disability and a low death rate of 31% (21 % when non-MS deaths were excluded), whereas an increase in the fat intake to an average of 25 or 42 g/d was accompanied by striking increase in average disability (to a need for bed care) and near tripling of the death rate, to 79% and 81 %, respectively. Here we examine the effects of consumption of low fat diets in relation to severity of MS in patients from the same study. The
Patients and methods The 156 patients who maintained contact with the MS clinic from December, 1948, to the end of April, 1954, formed the basis of this study. 2 patients were rejected because of uncertain diagnosis and 4 were lost early in the study. 6 more patients, who had been followed
BARBARA BREWER DUGAN
during the first 20 years, were lost, leaving 144 patients to complete the study. For most patients (72%) the diagnosis was made at the Montreal Neurological Institute; for 22% by qualified consulting neurologists in the Veterans Administration hospitals in Canada and Northern New York State; and for 6% by R.L.S. The distribution of patients in terms of age at onset of MS, neurological disability, and duration of disease before dieting were shown in table i of a former paperThe criteria for a diagnosis of MS were two or more episodes of an exacerbating-remitting neurological disease plus a history and physical findings indicating that the central nervous system had sustained damage disseminated both in time and space. In all cases the standard diagnostic tests available at the time (pneumograms, myelogram, spinal fluid examination, and electroencephalogram) did not rule out the probability of MS, and in all but 2 cases, subsequent clinical events confirmed the diagnosis of an exacerbating-remitting neurological disease assumed to be MS. Since 1952 neurological status has been graded on a 7-point scale, with one neurological grade being approximately equal to two points on the Kurtzke scale.9 0 normal performance and normal neurological findings, frequent fatigue, occasional exhaustion; 1= normal performance physically and mentally, neurological signs present, frequent fatigue, periodic exhaustion; 2 = mildly impaired physical performance but ambulant, neurological signs present, able to work part time or full time, fatigue present and exhaustion periodic, occasionally variable =
memory impairment; 3 = severely impaired performance but ambulant, able to work (usually part time), neurological impairment usually widespread, variable memory impairment frequently present; 4 wheelchair needed, memory often impaired; =
5 confined to bed and chair; and 6 = deceased. Details of patient care and a detailed description of the diet have been published elsewhere.7,1O Briefly, from 1949 to mid-1951, fat intake was reduced from approximately 125 g/day to 20-30 g/d, mostly by cutting down on milk and fat from other animal sources. =
Department of Neurology, Oregon Health Sciences University, Portland, Oregon, OR 97201, USA (R. L. Swank, MD, B. B Dugan) Correspondence to Dr R. L. Swank
ADDRESS.
EPIDEMIOLOGY Outbreak of Pontiac fever due to Legionella anisa
An outbreak of Pontiac fever occurred among 34 of 56 people attending conferences at a hotel in Santa Clara County, California, in 1988. Two groups had an acute febrile upper respiratory illness, with a mean attack rate of 82% and a mean incubation period of 56 hours. Symptoms resolved spontaneously within 5 days. Legionella anisa, which had not previously been associated with outbreaks of Pontiac fever or legionnaires’ disease, was isolated from a decorative fountain in the hotel lobby. In addition, 5 of 8 pairs of serum samples from cases showed a more than fourfold rise in antibody titre to the L anisa recovered from the fountain. 42% of hotel employees had titres ≥256 against L anisa, whereas none of 48 serum samples from matched controls had titres ≥128. The findings raise concern about water treatment protocols for extent of disease that might be caused by exposure to aerosols containing L anisa and other Legionella
species.
Before the outbreak there was no set schedule for cleaning the fountain. The fountain used recirculated water, and cleaning consisted of draining the pool, mopping the tile with hot water, polishing the marble top, and running hot water through the nozzles and jets of the fountain. No disinfecting chemicals were used. Here we report the association of Pontiac fever due to a newly recognised pathogen, L anisa, with a decorative fountain.
Methods
Epidemiology Initial information
was
obtained from
cases
by telephone
8-10
days after exposure. A questionnaire was then developed and sent to all 56 persons attending the conferences. They were asked about specific activities at the hotel, symptoms, time of onset, baseline health status, smoking history, and secondary illness among contacts. A case was defined as illness with fever or chills and either (1) cough or dry sore throat or (2) headache or muscle aches.
Serology Introduction
On April 20 and 22, 1988, two day-long conferences were held at a hotel in Santa Clara County, California. Both meetings were conducted in the same conference room on the ground floor, near the lobby. Both groups of conference participants were served breakfast and lunch at tables arranged around a decorative fountain in the lobby. The Santa Clara County Health Department was first notified of an outbreak of an influenza-like illness on April 28. The people affected suspected that the illness was food-related because several of them also had abdominal cramps. No hotel employee reported a similar illness. There was no previous record of illness from this establishment. The hotel is situated in a suburban area of the San Francisco peninsula. The structure is 4 years old, with three floors of rooms built around a central roofed atrium serving as a lobby, in the centre of which is a decorative fountain. The fountain is spherical and emits a fine aerosol. Within 100 feet of the lobby is an outdoor swimming pool and spa. The activities of both groups of conference participants were confined to the ground floor and an underground parking area. The hotel is served by the municipal water supply. The hotel is heated and cooled by a waterless heat exchange unit.
Paired serum samples were obtained from 5 members of one group and from 3 of the other. The acute samples were obtained approximately Iweeks after onset and the convalescent sera 4
weeks later. The sera were tested for antibody against influenza A and B, parainfluenza, and respiratory syncytial virus (RSV). In view of the high attack rate, short incubation period, and typical symptoms, the possibility of Pontiac fever was raised at the outset; therefore, the same samples were also tested for antibody to Legionella pneumophila. Serum was also tested at the Centers for Disease Control (CDC) for L feeleii, another causative agent of Pontiac fever. Upon recovery of Legionella anisa from the fountain water, CDC was requested to test those paired samples for seroconversion to L anisa as well. In addition, antibody prevalence to L anisa was studied among 24 hotel workers who provided specimens, and their antibody status was contrasted with that of 48 healthy controls who had undergone premarital blood tests at the county health department. The controls were matched to hotel workers by age, sex, and ethnic group. ADDRESSES: Santa Clara County Health Department, San Jose, California (M. D Fenstersheib, MD, M. Miller, MD, C. Diggins, PHN, S. Liska, DrPH, L. Detwiler, BS); California Department of Health Services, Berkeley, California (S. B Werner, MD, D Lindquist, MPH), and Division of Bacterial Diseases, Center for Infectious Diseases, Centers for Disease Control, Atlanta, Georgia, USA (W. L. Thacker, MS, R. F Benson, MS). Correspondence to Dr M. D. Fenstersheib, Santa Clara County Health Department, 2220 Moorpark Avenue, San Jose, California 95128, USA.
36
CLINICAL FEATURES
feeleii. Water samples from the fountain paired samples showed a greater than fourfold rise in titre to L anisa; 4 pairs were from group A
pneumophila,
or
grew anisa. 5 of 8
and the other from group B. 10 (42%) of 24 hotel employees had antibody titres of 256 to L anisa. A raised titre from 6 other hotel workers gave titres of 128. By contrast, none of 48 control samples had titres of >_ 128 to L anisa. A raised titre correlated with length of employment at the hotel (p 0-028, by Fisher’s exact test) but not with age, sex, ethnic group, or time spent in the hotel lobby. =
Discussion were some differences between the two groups in clinical features. Onset of illness was more abrupt in group A (range = 52-86 h) than in group B (20-76 h), but in both groups incubation periods were compatible with Pontiac fever, which commonly has an incubation period of 24-48 h.1 The attack rate was higher in group A than in group B. Possible reasons for this discrepancy are reporting bias, differences in the degree or length of exposure to the fountain, inconsistency of air circulating factors between the two days, or differences in immunity between the two groups (eg, group A was younger and possibly more
There
*p = < U5 (x’) between the two groups.
susceptible).
Water sampling
heating and cooling units of the hotel were examined and standing water in the system was searched for. No standing water was found on the roof or in the duct system 10 days after the The
conference. Water from the fountain was tested but not that from the swimming pool since conference attendants had not had access to the pool.
The water in the fountain was never disinfected and this permitted contamination by L anisa and its persistence. Transmission of infection was probably via aerosols of the fountain water. After the outbreak, disinfection procedures were
instituted.
The clinical presentation was that of an influenza-like illness with an extraordinarily high attack rate, brief incubation period, and absence of secondary spread. The attack rate was higher among those attending the conference on April 20 (group A, 94%, 17/18) than among those attending on April 22 (group B, 71%, 17/24), but this difference was not significant. Group A was youner (median age of 36 years) than group B (median age 46). Few reported conditions that could predispose to illness, such as current smoking (3), chronic lung disease (1), use of corticosteroids (1), immunodeficiency (0), or history of splenectomy (1). None of the respondents had used the swimming pool or the spa. All had eaten near the fountain. First exposure for both groups was judged to be 8 am on the day of the respective seminars. The median incubation periods were 58 h for group A and 54 h for group B (table). The median duration of illness for each group was 2 days, with a range of 2-6 days for group A and 1-8 days for group B. Symptoms reported by 80% or more of both groups included headache, muscle ache, chills, fever, and malaise. A greater proportion of group A reported cough and chest pain than was the case in group B (X2, p < 005). There was no secondary spread within households. 9 persons sought medical care. No one was admitted to hospital and all recovered uneventfully.
This investigation showed that Legionella anisa can cause outbreaks of human disease. It was recovered from the suspect source (the decorative fountain), greater than fourfold antibody titre rises were found in cases, and high antibody levels to L anisa were prevalent among hotel workers but absent in healthy controls. Pontiac fever has been associated with four species of Legionella and is characterised by a sudden onset of fever, headache, myalgias, cough, and general debility. It does not progress to pneumonia nor is it contagious. No deaths have been reported and convalescence is generally complete and uneventful.2 Only pneumophila serogroups 1 and 6, L feeleii serogroup 1, and L micdadei have previously been linked to seven outbreaks of Pontiac fever.3-5 Though it was not known to be pathogenic at the time, L anisa has been isolated from potable hospital water in both Chicago and Los Angeles, and from an industrial cooling tower in New York. It was not until 1989 that L anisa was reported to be a pathogen. It was recovered from the bronchial lavage specimen of an immunocompromised patient with pneumoniaand in France from the pleural fluid of another immunocompromised individual with cancer.s With the increasing use of decorative fountains in enclosed spaces, such as shopping malls and hotels, possible transmission of the agents causing both legionnaires’ disease and Pontiac fever by aerosol exposure must be considered. All such fountains using recirculated water should be maintained and disinfected to prevent future cases and outbreaks of legionellosis.
Serology/water sampling The 8 paired samples of serum showed no rise in titres to influenza A or B, parainfluenza, RSV, Legionalla
We thank Barbara Sullivan, PHN, formerly of the Santa Clara County Health Department; Louise Ottis of the Division of Environmental Health, Santa Clara County Health Department; and Leon Alevantis and Janet Macher of the Air and Industrial Hygiene Laboratory of the California Department of Health Services.
Results
Epidemiology
37
REFERENCES
5.
Department of Health Services. Control of Communicable Diseases in California, 1983: 245-47. 2. Dave GS, Winn WC Jr. Legionnaires’ disease: respiratory infections caused by Legionella bacteria. Clin Chest Med 1987; 8: 419-48. 3. McDade JE, Shepard CC, Fraser DW, et al. Legionnaires’ disease: isolation of a bacterium and demonstration of its role in our respiratory 1. California
disease. N Engl J Med 1977; 297: 1197-203. 4. Broome CV. Current issues of epidemiology in legionellosis. In: Thornsberry C, Balows A, Feeley JC, Jakubowski W, ed. Legionella, Proceedings of the 2nd International Symposium. Washington DC: American Society for Microbiology, 1984: 205-09.
Wrench JG, Collier PW, et al. outbreak in non-pneumonic legionellosis due to Lancet 1989; i: 316-18.
Goldberg DJ,
Lochgoilhead fever Legionella micdadei.
GW, Feeley JC, Steigerwalt A, et al. Legionella anisa: a new species of Legionella isolated from potable waters and a cooling tower. Appl Environ Microbiol 1985; 49: 305-09. 7. Thacker WL, Benson RF, Hawes L, Mayberry WR, Brenner DJ. Characterization of a Legionella anisa strain isolated from a patient with pneumonia. J Clin Microbiol 1990; 28: 122-23. 8. Bornstein N, Mercatello A, Marmet D, Surgot M, Deveaux Y, Fleurette J. Pleural infection caused by Legionella anisa. J Clin Microbiol 1989; 6. Gorman
27: 2100-101.
VIEWPOINT Effect of low saturated fat diet in early and late cases of multiple sclerosis ROY LAVER SWANK
144 multiple sclerosis patients took a low-fat diet for 34 years. For each of three categories of
neurological disability (minimum, moderate, severe) patients who adhered to the prescribed diet (≤20 g fat/day) showed significantly less deterioration and much lower death rates than did those who consumed more fat than prescribed (>20 g fat/day). The greatest benefit was seen in those with minimum disability at the start of the trial; in this group, when those who died from non-MS diseases were excluded from the analysis, 95% survived and remained physically active.
Introduction
suggestion, made in 1950, that the frequency of multiple sclerosis (MS) was related to fat consumption1 was based on the relative frequencies of multiple sclerosis (MS) and the calculated fat consumption of different populations, and it was later supported by a Norwegian study of the incidence of MS and nutrition,2by analysis of similar data from many geographical areas,3and by clinical studies.4-8 One study, in which patients were followed up for 34 years, implicated saturated animal fats- the lowest saturated fat consumers (20 g/d; mean 17 g/d) showed little worsening of disability and a low death rate of 31% (21 % when non-MS deaths were excluded), whereas an increase in the fat intake to an average of 25 or 42 g/d was accompanied by striking increase in average disability (to a need for bed care) and near tripling of the death rate, to 79% and 81 %, respectively. Here we examine the effects of consumption of low fat diets in relation to severity of MS in patients from the same study. The
Patients and methods The 156 patients who maintained contact with the MS clinic from December, 1948, to the end of April, 1954, formed the basis of this study. 2 patients were rejected because of uncertain diagnosis and 4 were lost early in the study. 6 more patients, who had been followed
BARBARA BREWER DUGAN
during the first 20 years, were lost, leaving 144 patients to complete the study. For most patients (72%) the diagnosis was made at the Montreal Neurological Institute; for 22% by qualified consulting neurologists in the Veterans Administration hospitals in Canada and Northern New York State; and for 6% by R.L.S. The distribution of patients in terms of age at onset of MS, neurological disability, and duration of disease before dieting were shown in table i of a former paperThe criteria for a diagnosis of MS were two or more episodes of an exacerbating-remitting neurological disease plus a history and physical findings indicating that the central nervous system had sustained damage disseminated both in time and space. In all cases the standard diagnostic tests available at the time (pneumograms, myelogram, spinal fluid examination, and electroencephalogram) did not rule out the probability of MS, and in all but 2 cases, subsequent clinical events confirmed the diagnosis of an exacerbating-remitting neurological disease assumed to be MS. Since 1952 neurological status has been graded on a 7-point scale, with one neurological grade being approximately equal to two points on the Kurtzke scale.9 0 normal performance and normal neurological findings, frequent fatigue, occasional exhaustion; 1= normal performance physically and mentally, neurological signs present, frequent fatigue, periodic exhaustion; 2 = mildly impaired physical performance but ambulant, neurological signs present, able to work part time or full time, fatigue present and exhaustion periodic, occasionally variable =
memory impairment; 3 = severely impaired performance but ambulant, able to work (usually part time), neurological impairment usually widespread, variable memory impairment frequently present; 4 wheelchair needed, memory often impaired; =
5 confined to bed and chair; and 6 = deceased. Details of patient care and a detailed description of the diet have been published elsewhere.7,1O Briefly, from 1949 to mid-1951, fat intake was reduced from approximately 125 g/day to 20-30 g/d, mostly by cutting down on milk and fat from other animal sources. =
Department of Neurology, Oregon Health Sciences University, Portland, Oregon, OR 97201, USA (R. L. Swank, MD, B. B Dugan) Correspondence to Dr R. L. Swank
ADDRESS.
