Hostname: page-component-cd9895bd7-mkpzs Total loading time: 0 Render date: 2024-12-27T02:02:22.653Z Has data issue: false hasContentIssue false

Food-borne bacterial infections

Published online by Cambridge University Press:  06 April 2009

R. W. Lacey
Affiliation:
Department of Clinical Microbiology, University of Leeds, UK

Summary

The number of episodes of diseases caused by bacterial contamination of food has shown a real increase by about threefold in the last decade in the U.K. The numbers for 1992 are estimated to be 2 million. The causes are multifactorial and complex, and 4 representative pathogens are reviewed. The main increase in diseases due to salmonella has been caused by Salmonella enteritidis, especially from eggs. The commonest bacterial food pathogen is Campylobacter, which causes an illness with specific season peaks in May and June. This may be related to the activities of birds and mammals. Both these bacteria cause common diseases that are rarely fatal. In contrast, Listeria and E. coli are ubiquitous but rarely produce disease; however, the consequences of any such illness are often dire. Procedures and techniques are available for the control of most of these diseases, but society does not seem determined to implement them.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1993

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Aho, M., Kwoki, M., Rantelin, H. & Kosunen, T. V. (1989). Waterborne outbreak of Campylobacter enteritis after outdoors infantry drill in Utti, Finland. Epidemiology and Infection 103, 133–41.CrossRefGoogle ScholarPubMed
Alderton, G., Ward, W. H. & Ferold, H. L. (1946).Identification of the bacteria-inhabiting iron-binding protein of egg white as conalbumen. Archives of Biochemistry 11, 913.Google Scholar
Bearns, R. E. & Giraud, K. F. (1958) The effect of pasteurization on Listeria monocytogenes. Canadian Journal of Microbiology 4, 5561.CrossRefGoogle ScholarPubMed
Beauchat, A. (1990). Presence and public health implications of Listeria monocytogenes in vegetables. Comprehensive Conference on Listeria monocytogenes.Society for Industrial Microbiology.Rohnert Park, California,October 1988. Foodborne Listeriosis, pp. 175–182. New York:Elsevier.Google Scholar
Bille, J. (1990). Epidemiology of human listeriosis in Europe. Comprehensive Conference on Listeria monocytogenes.Society for Industrial Microbiology.Rohnert Park, California,October 1988. Foodborne Listeriosis, pp. 71–74. New York:Elsevier.Google Scholar
Black, R. E., Levine, M. M., Clements, M. L., Hughes, T. P. & Blaser, M. J. (1988) Experimental Campylobacter jejuni infection in humans. Journal of Infectious Disease 157, 472–9.CrossRefGoogle ScholarPubMed
Blaser, M. J., Taylor, D. N. & Feldman, R. A. (1983) Epidemiology of Campylobacter jejuni infections. Epidemiology Reviews 5, 157–76.CrossRefGoogle ScholarPubMed
Bradshaw, J. G., Peeler, J. T., Corwin, J. J., Hunt, J. M. & Twedt, R. (1987) Thermal resistance of Listeria monocytogenes in dairy products. Journal of Food Protection 50, 543–4.CrossRefGoogle ScholarPubMed
Broome, C. V. (1990). Comprehensive Conference on Listeria monocytogenes.Society for Industrial Microbiology.Rohnert Park, California,October 1988. Foodborne Listeriosis, pp. 61–66. New York:Elsevier.Google Scholar
Butzler, J.-P., Dekeyser, P., Detrain, M. & Dehaen, F. (1973) Related vibrios in stools. Journal of Paediatrics 82, 493–5.CrossRefGoogle ScholarPubMed
Cassidy, P. K. & Brackett, R. E. (1989) Methods and media to isolate and enumerate Listeria monocytogenes: A review. Journal of Food Protection 52, 207–41.CrossRefGoogle Scholar
CDR Reports. Weekly communicable disease reports from the Public Health Laboratory Service, 61 Colindale Avenue, London NW9 SEQ.Google Scholar
Chapman, P. A., Siddons, C. A., Zakik, P. M. & Jewes, L. (1991) An improved selective medium for the isolation of Escherichia coli O157. Journal of Medical Microbiology 35, 107–10.CrossRefGoogle ScholarPubMed
Chapman, P. A., Wright, D. J. & Norman, P. (1989) Verotoxin-producing Escherichia coli infections in Sheffield: cattle as a possible source. Epidemiology and Infection 102, 439–45.CrossRefGoogle ScholarPubMed
Clay, C. E. & Board, R. G. (1991) Growth of Salmonella enteritidis in artificially contaminated hens' shell eggs. Epidemiology and Infection 106, 271–81.CrossRefGoogle ScholarPubMed
Conlan, J. W. & North, R. J. (1992) Roles of Listeria monocytogenes virulence factors distinct in survival: virulence factors distinct from listeriolysin are needed for the organism to survive an early neutrophil-mediated host defense mechanism. Infection and Immunity 60, 951–7.CrossRefGoogle ScholarPubMed
Cowden, J., Chisholm, D., O'Mahoney, M., Mawer, S. L., Rowe, B. & Bartlett, C. L. R. (1989) Two outbreaks of Salmonella enteritidis PT4 infection associated with the consumption of fresh shell-egg products. Epidemiology and Infection 103, 4753.CrossRefGoogle Scholar
Coyle, E. G., Palmer, S. R., Ribeiro, C. D., Jones, H. I., Howard, A. J., Ward, L. & Rowe, B. (1988) Salmonella enteritidis phage type 4 infection. Association with hens' eggs. Lancet ii, 1295–7.CrossRefGoogle Scholar
D'Aoust, J.-Y. (1985) Infective dose of Salmonella typhimurium in cheddar cheese. American Journal of Epidemiology 122, 717–20.CrossRefGoogle ScholarPubMed
Department of Health (1989). Chilled and Frozen. Guidelines on Cook-chill and Cook-freeze Catering Systems. London: HMSO.Google Scholar
Donnelly, C. W., Briggs, E. H. & Donnelly, L. S. (1987) Comparisons of heat resistance of Listeria monocytogenes in milk determined by two methods. Journal of Food Protection 49, 994–8.CrossRefGoogle Scholar
Doyle, M. P., Glass, K. A., Benny, J. T., Garcia, G. A., Pollard, D. J. & Shultz, R. D. (1987) Survival of Listeria monocytogenes in milk during high-temperature, short-time pasteurization. Applied and Environmental Microbiology 53, 1433–8.CrossRefGoogle ScholarPubMed
Duguid, J. P. & North, R. A. E. (1991) Eggs and salmonella food-poisoning: an evaluation. Journal of Medical Microbiology 34, 6572.CrossRefGoogle ScholarPubMed
Editorial (1988) The chicken and the egg. Lancet ii, 720–2.Google Scholar
Fenlon, D. R. (1985) Wild birds and silage as reservoirs for Listeria in the agricultural environment. Journal of Applied Bacteriology 59, 537–43.CrossRefGoogle ScholarPubMed
Foxall, P. A., Hu, L-T. & Mobley, L. T. (1992) Use of polymerase chain reaction-amplified Helicobacter pylori urease structural genes for differentiation of isolates. Journal of Clinical Microbiology 30, 739–41.CrossRefGoogle ScholarPubMed
Fricker, C. R. & Park, R. W. A. (1989) A two-year study of the distribution of ‘thermophilic’ Campylobacters in human, environmental and food samples from the Reading area with particular reference to toxin production and heat-stable serotype. Journal of Applied Bacteriology 66, 477–90.CrossRefGoogle ScholarPubMed
Fujimoto, S. & Amako, K. (1990) Guillain–Barré syndrome and Campylobacter jejuni infection. Lancet i, 1350.CrossRefGoogle Scholar
Garayzabal, J. F. F., Rodriguez, L. P., Vazquez, J. A. G., Ferri, E. G. R. Boland, Dieste, V. B., Cancelo, J. L. B. & Fernandez, G. S. (1987) Survival of Listeria monocytogenes in raw milk treated in a pilot plant size pasteurizer. Journal of Applied Bacteriology 63, 533–7.CrossRefGoogle Scholar
Gellin, B. G. & Broome, C. B. (1989) Listeriosis. Journal of the American Medical Association 261, 1313–20.CrossRefGoogle ScholarPubMed
Giesendorf, B. A. J., Quint, W. G. V., Henkens, M. H. C., Stegeman, H., Huf, F. A. & Niesters, H. G. M. (1992) Rapid and sensitive detection of Campylobacter spp. in chicken products using the polymerase chain reaction. Applied and Environmental Microbiology 58, 3804–8.CrossRefGoogle ScholarPubMed
Giessen, A. van de, Mazurier, S-I., Jacobs-Reitsma, W., Jansen, W., Berkers, P., Ritmeester, W. & Wernars, K. (1992) Study on the epidemiology and control of Campylobacter jejuni in poultry broiler flocks. Applied and Environmental Microbiology 58, 1913–17.CrossRefGoogle Scholar
Gill, O. N., Sockett, P. N., Bartlett, C. L. R., Vaile, M. S. B., Rowe, B., Gilbert, R. J., Dulake, C., Murrell, H. C. & Salmso, S. (1983) Outbreak of Salmonella napoli infection caused by contaminated chocolate bars. Lancet i, 574–7.CrossRefGoogle Scholar
Gray, M. L. & Killinger, A. H. (1966) Listeria monocytogenes and listeric infections. Bacteriological Reviews 30, 309–82.CrossRefGoogle ScholarPubMed
Griffiths, P. L. & Park, R. W. A. (1990) Campylobacters associated with human diarrhoeal disease. Journal of Applied Bacteriology 69, 281301.CrossRefGoogle ScholarPubMed
Gross, R. J. (1992). Canada, cows and E. coli. Medical Laboratory World, 01, 79.Google Scholar
Harris, N. V., Kimball, T., Weiss, N. S. & Nolan, C. (1986) Dairy products, produce and other non-meat foods as possible sources of Campylobacter jejuni and Campylobacter coli enteritis. Journal of Food Protection 49, 347–51.CrossRefGoogle ScholarPubMed
Harris, N. V., Weiss, N. S. & Nolan, C. M. (1986) The role of poultry and meats in the etiology of Campylobacter jejuni/coli enteritis. American Journal of Public Health 76, 407–11.CrossRefGoogle ScholarPubMed
Hayes, P. R. (1992). Food Microbiology and Hygiene, 2nd edition. London: Elsevier.Google Scholar
Healing, T. D., Greenwood, M. H. & Pearson, A. D. (1992) Campylobacters and enteritis. Reviews in Medical Microbiology 3, 159–67.Google Scholar
Hird, D. w. (1990). Animals and humans as reservoirs for listeriosis. Comprehensive Conference on Listeria monocytogenes.Society for Industrial Microbiology.Rohnert Park, California,October 1988. Foodborne Listeriosis, pp. 31–40. New York:Elsevier.Google Scholar
Hooker, J. (1988). Microbes à la carte. New Scientist, 9 06, 6770.Google Scholar
Hopper, S. A. & Mawer, S. (1988) Salmonella enteritidis in a commercial layer flock. Veterinary Record 123, 351.CrossRefGoogle Scholar
Hudson, S. J., Sobo, A. O., Russel, K. & Lightfoot, N. F. (1990) Jackdaws as potential source of milk-borne Campylobacter jejuni infection. Lancet 1, 1160.CrossRefGoogle Scholar
Humphrey, T. J., Greenwood, M., Gilbert, R. J., Rowe, B. & Chapman, P. A. (1989) The survival of salmonellas in shell eggs cooked under stimulated domestic conditions. Epidemiology and Infection 103, 3545.CrossRefGoogle Scholar
Humphrey, T. J. & Hart, R. J. C. (1988) Campylobacter and salmonella contamination of unpasteurised cows' milk on sale to the public. Journal of Applied Bacteriology 63, 21–5.CrossRefGoogle Scholar
Humphrey, T. J., Mead, G. C. & Rowe, B. (1988) Poultry meat as a source of human salmonellosis in England and Wales. Epidemiology and Infection 100, 175–84.CrossRefGoogle ScholarPubMed
Humphrey, T. J., Whitehead, A., Gawler, A. H. L., Henley, A. & Rowe, B. (1991) Numbers of Salmonella enteritidis in the contents of naturally contaminated hens' eggs. Epidemiology and Infection 106, 489–96.CrossRefGoogle ScholarPubMed
Jones, K., Betaieb, M. & Telford, D. R. (1990) Correlation between environmental monitoring of thermophilic Campylobacters in sewage effluent and the incidence of Campylobacter infection in the community. Journal of Applied Bacteriology 69, 235–40.CrossRefGoogle ScholarPubMed
Kaldor, J. & Speed, B. R. (1984) Guillain–Barré syndrome and Campylobacter jejuni: a serological study. British Medical Journal 288, 1867–70.CrossRefGoogle ScholarPubMed
Kapperud, G. & Rosef, O. (1983) Avian wildlife reservoir of Campylobacter fetus subsp. jejuni, Yersinia spp. and Salmonella spp. in Norway. Applied Environmental Microbiology 45, 375–80.CrossRefGoogle ScholarPubMed
Kapperud, G., Skjerve, E., Bean, N. H., Ostroff, S. M. & Lassen, J. (1992) Risk factors for sporadic Campylobacter infections: results of a case-control study in Southeastern Norway. Journal of Clinical Microbiology 30, 3117–21.CrossRefGoogle ScholarPubMed
Kathariou, S. (1990). Laboratory studies of virulence mechanisms of Listeria. Comprehensive Conference on Listeria monocytogenes.Society for Industrial Microbiology.Rohnert Park, California,October 1988. Foodborne Listeriosis, pp. 55–60. New York:Elsevier.Google Scholar
Kerr, K. G., Dealler, S. F. & Lacey, R. W. (1988) Listeria in cook-chill food. Lancet ii, 37–8.CrossRefGoogle Scholar
Kerr, K. G., Rotowa, N. A., Hawkey, P. M. & Lacey, R. W. (1990) An evaluation of the Mast ID and AP150CH systems for the identification of Listeria spp. Applied and Environmental Microbiology 56, 657–60.CrossRefGoogle ScholarPubMed
King, E. O. (1957) Human infection with Vibrio fetus and a closely related Vibrio. Journal of Infectious Diseases 101, 119–28.CrossRefGoogle Scholar
Konowalchuk, J., Speirs, J. I. & Stavric, S. (1977) Vero response to a cytotoxin of Escherichia coli. Infection and Immunity 18, 775–9.CrossRefGoogle ScholarPubMed
Lacey, R. W. (1989). Safe Shopping, Safe Cooking, Safe Eating. London: Penguin.Google Scholar
Lacey, R. W. (1991). Unfit for Human Consumption. London: Souvenir Press.Google Scholar
Levy, A. J. (1946) A gastroenteritis outbreak probably due to a bovine strain of vibrio. Yale Journal of Biological Medicine 18, 243–58.Google Scholar
Marshall, B. J., Royce, H., Annear, D. I., Goodwin, C. S., Pearman, J. W., Warren, J. R. & Armstrong, J. A. (1984) Original isolation of Campylobacter pyloridis from human gastric mucosa. Microbiological Letters 25, 83–8.Google Scholar
McFadyean, J. & Stockman, S. (1913). Report of the Departmental Committee Appointed by the Board of Agriculture and Fisheries to Enquire into Epizootic Abortion, part III. London: HMSO.Google Scholar
McNulty, C. A. M. (1987) The treatment of Campylobacter infections in man. Journal of Antimicrobial Chemotherapy 19, 281–4.CrossRefGoogle ScholarPubMed
Moureau, P., Derclaye, I., Gregoire, D., Janssen, M. & Cornelis, G. R. (1989) Campylobacter species identification based on polymorphism of DNA encoding on rRNA. Journal of Clinical Microbiology 27, 1514–17.CrossRefGoogle ScholarPubMed
Munroe, D. L., Prescott, J. F. & Penner, J. L. (1983) Campylobacter jejuni and Campylobacter coli serotypes isolated from chickens, cattle and pigs. Journal of Clinical Microbiology 18, 877–81.CrossRefGoogle ScholarPubMed
Nuijten, P. J. M., Astern, F. J. A. M. van, Gaastra, W. & van der Zeijst, B. A. M. (1990) Structural and functional analysis of two Campylobacter jejuni flagellin genes. Journal of Biological Chemistry 265, 17798–804.CrossRefGoogle ScholarPubMed
O'Brien, J. S. P. (1988) Salmonella enteritidis in broiler chickens. Veterinary Record 122, 214.CrossRefGoogle ScholarPubMed
Pacha, R. E., Clark, G. W., Williams, E. A. & Carter, A. M. (1988) Migratory birds of central Washington as reservoirs of Campylobacter jejuni. Canadian Journal of Microbiology 34, 80–2.CrossRefGoogle Scholar
Pai, C. H., Gordon, R., Sims, H. V. & Bryan, L. E. (1984) Sporadic cases of haemorrhagic colitis associated with Escherichia coli O157:H7. Annals of Internal Medicine 101, 738–42.CrossRefGoogle ScholarPubMed
Palmer, S. R., Gully, P. R., White, J. M., Pearson, A. D., Suckling, W. G., Jones, D. M., Rawes, J. C. L. & Penner, J. L. (1983) Water-borne outbreak of Campylobacter gastroenteritis. Lancet i, 287–90.CrossRefGoogle Scholar
Penner, J. L. (1988) The genus Campylobacter: a decade of progress. Clinical Microbiology Reviews 1, 157–72.CrossRefGoogle ScholarPubMed
Perales, I. & Audicana, A. (1988) Salmonella enteritidis. Lancet ii, 1133.CrossRefGoogle Scholar
Ratnam, S., March, S. B. & Sprague, W. D. (1986). Are humans a source of Escherichia coli O157:H7, the agent of haemorrhagic colitis? New England Journal of Medicine 2, 1612.Google Scholar
Raveneau, J., Geoffroy, C., Beretti, J-L., Gaillard, J-L., Alouf, J. E. & Berche, P. (1992) Reduced virulence of a Listeria monocytogenes phospholipase-deficient mutant obtained by transposon insertion into the zinc metalloprotease gene. Infection and Immunity 60, 916–21.CrossRefGoogle ScholarPubMed
Rhodes, K. M. & Tattersfield, A. E. (1982) Guillain-Barré syndrome associated with Campylobacter infection. British Medical Journal 285, 173–4.CrossRefGoogle ScholarPubMed
Riley, L. W., Remis, R. S., Helgerson, S. D. & McGee, H. B. (1983) Haemorrhagic colitis associated with a rare Escherichia coli serotype. New England Journal of Medicine 308, 681–5.CrossRefGoogle ScholarPubMed
Rollins, D. M. & Colwell, R. R. (1986) Viable but non-culturable stage of Campylobacter jejuni and its role in survival in the natural aquatic environment. Applied and Environmental Microbiology 52, 531–8.CrossRefGoogle Scholar
Romaniuk, P. J., Zoltowska, B., Trust, T. J., Lance, D. J., Olsen, G. J., Pace, N. R. & Stahl, D. A. (1987) Campylobacter pylori, the spiral bacterium associated with human gastritis, is not a true Campylobacter spp. Journal of Bacteriology 199, 2137–41.CrossRefGoogle Scholar
Ropper, A. H. (1988) Campylobacter diarrhoea and Guillain–Barré syndrome. Archives in Neurology 45, 655–6.CrossRefGoogle ScholarPubMed
Rosef, O. & Kapperud, G. (1983) Houseflies (Musca domestica) as possible vectors of Campylobacter fetus subsp. jejuni. Applied and Environmental Microbiology 45, 381–3.CrossRefGoogle ScholarPubMed
Rosenow, E. M. & Marth, E. H. (1987) Growth of Listeria monocytogenes in skimmed, whole and chocolate milk, and in whipping cream during incubation at 4, 8, 13, 21 and 35 °C. Journal of Food Protection 50, 453–9.CrossRefGoogle Scholar
Rowe, B., Begg, N. T., Hutchinson, D. N., Dawkins, H. C., Gilbert, R. J., Jacob, M., Hales, B. H., Rae, F. A. & Jepson, M. (1988) Salmonella ealing infections associated with the consumption of infant dried milk. Lancet i, 900–3.Google Scholar
Ryser, E. G. & Martin, E. M. (1987) Behaviour of Listeria monocytogenes during the manufacture and ripening of cheddar cheese. Journal of Food Protection 40, 713.CrossRefGoogle Scholar
Louis, M. E. St., Dale, L. M., Potter, M. E., Thomas, M. D., Guzewich, J. J., Tauxe, R. V. & Blake, P. A. (1988) The emergence of Grade A eggs as a major source of Salmonella enteritidis infections. Journal of the American Medical Association 259, 2103–7.CrossRefGoogle Scholar
Sanger, J. M., Sanger, J. W. & Southwick, F. S. (1992) Host cell actin assembly is necessary and likely to provide the propulsive force for intracellular movement of Listeria monocytogenes. Infection and Immunity 60, 3609–19.CrossRefGoogle ScholarPubMed
Schlech, W. F., Lavigne, P. J., Bortolulssi, R. A., Allen, A. C., Haldane, E. V., Wort, A. J., Hightower, A. W., Johnson, S. E., King, S. H., Nicholls, E. S. & Broome, C. V. (1983) Epidemic listeriosis: evidence for transmission by food. New England Journal of Medicine 308, 203–6.CrossRefGoogle ScholarPubMed
Sebald, M. & Véron, M. (1963) Teneur en bases de I' ADN et classification des vibrions. Annates de l' Institut Pasteur (Paris) 105, 897910.Google Scholar
Sheeran, M. R. M., Kerr, K. G., Dealler, S. F., Hayes, P. R. & Lacey, R. W. (1989) Listeria survives microwave heating. Journal of Hospital Infection 14, 84–6.CrossRefGoogle ScholarPubMed
Skirrow, M. B. (1977) Campylobacter enteritis: a ‘new’ disease. British Medical Journal 89, 175–84.Google Scholar
Skirrow, M. B. (1990) Campylobacter. Lancet 336, 921–3.CrossRefGoogle ScholarPubMed
Smith, H. R., Rowe, B., Gross, R. J., Fry, N. K. & Scotland, S. M. (1987) Haemorrhagic colitis and vero cytotoxin-producing Escherichia coli in England and Wales. Lancet i, 1062–5.CrossRefGoogle Scholar
Southern, J. P., Smith, R. M. M. & Palmer, S. R. (1990) Bird attack on milk bottles: possible mode of transmission of Campylobacter jejuni to man. Lancet 336, 1425–7.CrossRefGoogle ScholarPubMed
Stern, N. J. & Kazmi, S. V. (1989). Campylobacter jejuni. In Foodborne Bacterial Pathogens (ed Doyle, M. P.), pp. 72110. New York: Marcel Dekker.Google Scholar
Taylor, D. E. & Courvalin, P. (1988) Mechanisms of antibiotic resistance in Campylobacter species. Antimicrobial Agents and Chemotherapy 32, 1107–12.CrossRefGoogle ScholarPubMed
Umunnabuike, A. C. & Irokanulo, E. A. (1986) Isolation of Campylobacter subsp. jejuni from Oriental and American cockroaches caught in kitchens and poultry houses in Vom, Nigeria. International Journal of Zoonoses 13, 180–6.Google ScholarPubMed
Vazquez-Boland, J-A., Kocks, C., Dramsi, S., Ohayon, H., Geoffroy, C., Mengaud, J. & Cossart, P. (1992) Nucleotide sequence of the lecithinase operon of Listeria monocytogenes and possible role of lecithinase in cell-to-cell spread. Infection and Immunity 60, 219–30.CrossRefGoogle ScholarPubMed
Vogt, R. L., Sours, H. E., Barrett, T., Feldman, R. A., Dickinson, R. J. & Witherell, L. (1982) Campylobacter enteritis associated with contaminated water. Annals of Internal Medicine 96, 292–6.CrossRefGoogle ScholarPubMed
Wang, Y. & Taylor, D. E. (1990) Natural transformation in Campylobacter species. Journal of Bacteriology 172, 949–55.CrossRefGoogle ScholarPubMed
Whelan, C. D., Monaghan, P., Girdwood, R. W. A. & Fricker, R. C. (1988) The significant of wild birds (Larus sp.) in the epidemiology of Campylobacter infections in humans. Epidemiology and Infection 101, 259–67.CrossRefGoogle ScholarPubMed
WHO (1988). Report of the WHO Informal Working Group on Foodborne Listeriosis, General, February 15–19 1988. Geneva; WHO.Google Scholar
Wright, E. P., Tillett, H. E., Hague, J. T., Clegg, F. G., Darnell, R., Culshaw, J. A. & Sorbell, J. A. (1983) Milk-borne Campylobacter enteritis in a rural area. Journal of Hygiene (Cambridge) 91, 227–33.CrossRefGoogle ScholarPubMed