- Email: [email protected]
CRYPTOSPORIDIUM AND DRINKING WATER
632
negative. No rheumatoid factor antibodies
were
detected.
or antinuclear or anti-DNA Antibodies against Toxoplasma, influenza and parainfluenza virus,
adenovirus, cytomegalovirus, respiratory syncytial virus, Mycoplasma pneumoniae, herpes simplex virus, Chlamydia psittaci, and Leptospira were not detected in
repeated serological investigations. HBs and HBe antigen (HbeAg) were negative; HBs antibodies were positive. 3 months after the first boost, after healing of the uveitis, the patient received the third dose of hevac B, against our advice. 4 days later she had the same symptoms as after the first boost, and bilateral
posterior uveitis was diagnosed again. No abnormal clinical and laboratory findings were found. Tests for rheumatoid factors and for antibodies against nuclei, mitochondria, and DNA were negative. The same antibodies tested after the first uveitis episode were again undetectable. Furthermore, no HIV antibody was found. HBsA was negative with an increased titre of HBs antibodies. HBeA and hepatitis B core antibodies were negative. Lymphocyte transformation tests (3H-thymidine incorporation) showed stimulated lymphocyte transformation by the vaccine. Similar results were observed in two other nurses immunised at the time with the same lot of vaccine. This is the first report of uveitis after hepatitis B vaccination. The causal relation with vaccination was shown by the re-exposure to the vaccine and renewed development of the eye disease. Bilateral uveitis occurred after both immunisations within a similar time, while known causes for uveitis could be excluded. The formation and peripheral deposition of immune complexes with complement activation is a major pathogenic mechanism in the development of uveitis in several infectious and systemic diseases.2 In our case, an immune complex disease was supported by the typical time interval of 3-4 days after antigen exposure while a cell-mediated immune response remained doubtful according to the results of the lymphocyte stimulation tests. Immune complex diseases such as cryoglobulinaemia and glomerulonephritis can be observed during chronic hepatitis B infection.3 The still unproven possibility that the hepatitis B virus could cause uveitis is suggested by the higher frequency of detectable HBsA and HBs antibodies in the blood of patients with uveitis,"and by a uveitis case with hepatitis B infection. We would suggest that the surface antigen of the vaccine and HBs antibodies of the immune response after vaccination formed immune complexes which initiated bilateral uveitis in our case. Thus, the surface antigen of the hepatitis virus could be responsible for the development of uveitis both after vaccination with HBsAg and during the course of hepatitis B infection. same
Outpatient Clinic and Division of Gastroenterology,
University Hospital, CH-4031 Basel, Switzerland
M. FRIED D. CONEN M. CONZELMANN E. STEINEMANN
1. Anonymous. The safety of hepatius B virus vaccine. MMWR 1983; 32: 134-36. 2. Rahi AHS, Holborow EJ, Perkins ES, Gungen YY, Dinning WJ. Immunological investigations in uveitis. Trans Ophthalmol Soc UK 1976; 96: 113. 3. London WT. Hepatitis B virus and antigen-antibody complex diseases. N Engl J Med 1977; 26: 1528-29. 4. Grob PJ, Martenet AC, Witmer R. Nonspecific immune parameters and hepatitis B antigens in patients with uveitis. Mod Probl Ophthalmol 1976; 16: 254-58. 5. Murray PI, Prasad J, Rahi AH. Status of hepatitis B virus in the aetiology of uveitis in Great Britain. Br J Ophthalmol 1983; 67: 685-87. 6. Farthing CF, Howard RS, Thin RN Papillitis and hepatitis B. Br Med J 1986; 292: 1712.
DETOXIFICATION OF PERTUSSIS VACCINES
SIR,-Dr Cameron (June 20, p 1427) does not refer to much of recent discussion about whole cell pertussis vaccines and their replacement by acellular vaccines. The presence in whole cell vaccines of histamine-sensitising factor (HSF) and lymphocytosispromoting factor (LPF) activities, now known to be properties of pertussis toxin,’ has been recognised for years. So too has the link between HSF activity and vaccine potency;’ indeed a small amount of active pertussis toxin will greatly enhance the potency of a variety of preparations in the intracerebral protection test.3 This has been a major problem in the development of acellular pertussis vaccines,
the
for which the aim has been to detoxify the toxin as completely as possible, precluding the use of the conventional potency assay. The need for thorough and irreversible detoxification follows from the recognition that this toxin has the potential to affect many physiological systems and might cause major reactions within the central nervous system. The precise mechanisms whereby this might happen, the dose of active pertussis toxin needed, and the involvement of other factors are all areas of conjecture. Agents used to detoxify pertussis toxin include formaldehyde and glutaraldehyde, which are well-tried for other bacterial toxins. However, the many variables in methodology can lead to products differing with regard to completeness of detoxification and stability. One cannot simply extrapolate from experience with other toxins because of differences in structure, (and hence reactivity with the detoxifying agent), molecular mechanism of action, and purity. Completeness of detoxification is usually assayed by the most sensitive
tests
available-ie, histamine sensitisation of mice and
clumping of Chinese hamster ovary (CHO) cells. Reversion to toxicity can be tested by incubating a vaccine for a long time at 4-37°C and then reassaying for active toxin. For the acellular pertussis vaccine developed at this centre, it is a requirement that active pertussin toxin should not be detectable in the vaccine before or after such incubations. Any acellular vaccine containing detoxified pertussis toxin should similarly be shown to be as completely and irreversibly detoxified as possible. In our experience whole cell vaccines fail this requirement since active toxin is readily detected by the histamine sensitisation test and, in contrast to Cameron’s findings, by the CHO cell assay also. The pertussin toxin content of whole cell vaccine in our previous. report’ was a crude estimate measured as LPF in mice; the content of inactive toxin could not be assessed. We now know that the ELISA for pertussis toxin does not work after this antigen has been subjected to the rigorous detoxification procedures used for acellular vaccines. Despite this apparent loss of ELISA antigenicity, the detoxified substance is a potent immunogen, giving rise to toxin-neutralising antibodies.5 In the future, inactive pertussin toxin or fragments thereof will probably be produced by techniques of molecular genetics or peptide synthesis, and chemical detoxification will become unnecessary. For the present, however, the procedures used ensure irreversible detoxification. This, together with the reduced endotoxin content, enables acellular vaccines to contain higher levels of toxin per dose (eg, the CAMR vaccine contains 10 Jlg detoxified pertussis toxin per dose besides 10 ng each of filamentous haemagglutinin and agglutinogens). Consequently, enhanced levels of serum antibody to PT are induced in comparison with the whole cell vaccine and this may allow a reduction in the number of doses required to induce full immunity.6 Experimental Pathology and Vaccine Research and Production Laboratories, Public Health Laboratory Service, Centre for Applied Microbiology and Research, Porton Down, Salisbury, Wiltshire SP4 0JG
L. A. E. ASHWORTH A. ROBINSON
JJ, Arai H, Bergman RK, Sadowski PL. Biological activities of crystalline pertussigen from Bordetella pertussis. Infect Immun 1981; 33: 820-26. 2. Pittman M. Comparison of the histamine-sensitising property with the protective activity of pertussis vaccines for mice. J Infect Dis 1951; 89: 300-04. 3. Robinson A, Irons LI. Synergistic effect of Bordetella pertussis lymphocytosis promoting factor on protective activities of isolated Bordetella antigens in mice. Infect Immun 1983; 40: 523-48. 4. Ashworth LAE, Robinson A, Irons LI, Morgan CP, Isaacs D. Antigens in whooping cough vaccine and antibody levels induced by vaccination of children. Lancet 1983; 1. Munoz
ii: 878-81. 5. Rutter DA, Ashworth LAE, Day A, Funnell S, Lovell F, Robinson A Tnal ofa new acellular pertussis vaccine in healthy adult volunteers. Vaccine (in press). 6. Olin P. Clinical results obtained to date in the Swedish trials. In. Workshop on acellular pertussis vaccines (sponsored by Interagency Group to Monitor Vaccine Development, Production and Usages, Bethesda, Maryland, September 1986): 106-10.
CRYPTOSPORIDIUM AND DRINKING WATER
SIR,-We read with interest the speculations on water-borne infection presented by Isaac-Renton and Cryptosporidium colleagues. Suspected water-borne cryptosporidiosis has been reported previously. 2,3
633 Sheffield area we observed a peak in human in April to October, 1986; such a peak was not observed in 1985 (or, so far, in 1987). Extensive epidemiological investigations failed to find a common source of food or milk or a consistent history of animal contact. However, of 104 patients with cryptosporidiosis, 84 (81 %) drank water supplied from the same reservoir complex. Use of a modified Ziehl-Neelsen staining technique4 and a monoclonal immunofluorescence tests revealed Cryptosporidium oocysts in faecal samples from cattle on farms adjoining the reservoir area, in the deposit from membrane-filtered surface water from the reservoir and from- streams feeding it, and in the intestinal contents of five apparently healthy brown trout (Salmo trutta) caught from the reservoir. Cattle are a well-documented source of Cryptosporidium oocysts.6,7 Contamination of the reservoir water from this source most probably happened via surface run-off after heavy rain. Reports of cryptosporidiosis in fish are uncommon ;8 such a finding confirms the widespread presence of Cryptosporidium in the aquatic environment. Cryptosporidium oocysts may not be effectively removed by normal water filtration methods;l they are resistant to many disinfectants9,10 and probably to routine water chlorination. Water-borne spread of Cryptosporidium is a possible, though as yet unproven, explanation for the peak in human cryptosporidiosis in the Sheffield area. In
the
cryptosporidiosis
We thank Mr D. Smith and Mr S. King of the Yorkshire Water Authority, and Mr F. G. Clegg of the Veterinary Investigation Centre, Sutton Bonnington, Loughborough, for their help. Public Health
Laboratory,
Northern General Hospital, Sheffield S5 7AU
BARBARA A. RUSH P. A. CHAPMAN
Environment Health Department, Sheffield
R. W. INESON
1. Isaac-Renton JL, Fogel D, Stibbs HH, Onngerth JE. Giardia and
Cryptosporidium in drinking water. Lancet 1987; i: 973-74. 2. Jokipii L, Pohjola S, Jokipii AMM. Cryptosporidium: a frequent finding in patients with gastrointestinal symptoms. Lancet 1983; ii: 358-61. 3. D’Antonio RG, Winnn RE, Taylor JP, et al. A waterborne outbreak of cryptosporidiosis in normal hosts. Ann Intern Med 1985; 103: 886-88. 4. Garcia LS, Brewer TC, Bruckner DA, Shimizu RY. Acid fast staining of Cryptosporidium from human faecal specimens. Clin Microbiol Newslett 1983; 5: 60-61. 5. McLauchlin
J, Casemore DP, Harrison DP, Gerson PJ, Samuel D, Taylor AG. Identification of Cryptosporidium oocysts by monoclonal antibody. Lancet 1987; i: 51 6. Angus KW. Cryptosporidiosis in man, domestic animals and birds: a review. J Roy Soc Med 1983; 76: 62-70. 7. Tzipori S. Cryptosporidium in animals and humans. Microbiol Rev 1983; 47: 84-96. 8. Hooveer DM, Hoerr FJ, Carlton WW, Hinsman EJ, Ferguson HW. Enteric cryptosporidiosis in a naso tang, Naso lituratus Bloch and Schneider. J Fish Dis 1981; 4: 425-28. 9. Angus KW, Sherwood D, Hutchinson G, Campbell I. Evaluation of the effect of two aldehyde-based disinfectants on the infectivity of faecal cryptosporidia for mice. Res Vet Sci 1982; 33: 379-81. 10. Campbell I, Tzipon S, Hutchinson G. Effect of disinfectants on survival of Cryptosporidium oocysts. Vet Rec 1982; 111: 414-15.
DIABETES MELLITUS AND LOW ENVIRONMENTAL MAGNESIUM LEVELS
S1R,-Chronic diabetes mellitus is associated with both low magnesium levels and serum hypomagnesaemia.1Indeed hypomagnesaemia even occurs in diabetic children,3in whom it is accompanied by significant changes in vascular reactivity. Despite the use of insulin, the incidence of high blood pressure in chronic tissue
diabetic patients varies between 40 and 80%.5 McNair et al6 have also shown that, in some diabetic patients, the degree of diabetic retinopathy is inversely related to the level of hypomagnesaemia. They therefore concluded that hypomagnesaemia is a risk factor in the development and progress of retinopathy. Similarly, Ewald et al3 have demonstrated that the degree of hypomagnesaemia in 27 children was positively correlated with future long-term diabetic
complications. The evidence therefore suggests that many of the problems associated with diabetes mellitus are linked to tissue and serum magnesium deficiencies. If so, one might anticipate that mortality from this disease would be lower in magnesium-enriched environments, which provide increased dietary levels of this element through drinking water and locally grown foods. To test
this hypothesis, I used Pearson correlation coefficients to compare the spatial distribution of diabetes mellitus mortality rates for the year 1980 in the USA with 221 climatic, hydrological, geological, social, and economic variables’ at the state level. I found that diabetes mortality was negatively correlated with both very high soil calcium (r = - 0-60742) and very high soil magnesium (r 0-56342). In contrast, positive correlations were found with the degree to which the state had been strip-mined (r 0-61291) and to the volume of industrial water withdrawals (r 0-60544) (p for all four correlations 0 0001). Stepwise multiple regression produced the following threevariable model, which could explain 64-2% of the variance = —
=
=
=
involved:
Mortality from diabetes mellitus 15-308 + (7-390 x En39) - (0-0310 x PVLB) - (0-0624 x PVHMg), where En39 is the percentage of the state disturbed by strip-mining (largely for coal), PVLB is the percentage of the state with soils that are very deficient in boron, and PVHMg is the percentage of the state with soils that are very rich in magnesium. Whilst co-linearity may be a problem in such stepwise regression, it is clear that a considerable portion of the diabetes mellitus mortality pattern in the USA can be explained in terms of soil magnesium variations. To explore the apparent relation further, Canadian agestandardised diabetes mortality rates for 1966-76 were compared with drinking-water analysis from 2633 locations. Mortality data =
available for both males and females from 258 electoral districts. There was a negative correlation between magnesium concentrations in drinking water and mortality from diabetes mellitus in males (r = - 0-20265) and females (r = - 0’23226). Although negative correlations also occurred between diabetes and calcium, these were lower: r==-012230 (p=00009) and r 0- 16780, respectively (p = 0-0001 unless otherwise stated). These analyses show that, in both the USA and Canada, mortality from diabetes mellitus tends to be increased where environmental magnesium and calcium levels are lowered-ie, in soft-water areas. This link between environmental magnesium, hypomagnesaemia, and diabetes mellitus is of more than academic interest. Cohen et al,8 for example, have reported that 8 young, diabetic hypomagnesaemic patients, treated with 750 mg magnesium oxide per day for three months, had complete reversal of the retinal vascular changes associated with high-renin essential hypertension. Normal serum magnesium levels were also restored. The value of treating diabetics with a magnesium supplement as well as insulin would therefore appear to warrant further study.
were
=
-
Department of Geography, University of Victoria, PO Box 1700, Victoria, British Columbia, Canada V8W 2Y2
HAROLD D. FOSTER
1. Aikawa JK.
Magnesium. Its biological significance. Boca Ratan, Florida: CRC Press, 1981. 2. Altura BC, Altura BT. New perspectives on the role of magnesium in the pathophysiology of the cardiovascular system I: Clinical aspects. Magnesium 1985; 4: 226-44. 3. Ewald U, Gebre-Medhin M, Tuvemo I. Hypomagnesaemia in diabetic children. Acta Paediatr Scand 1983; 72: 367-71. 4. Ewald U, Tuvemo T. Reduced vascular reactivity in diabetic children and its relation to diabetic control. Acta Paediatr Scand 1985, 74: 77-84. 5. Altura BM, Halevy S, Turlapaty PDMV. Vascular smooth muscle m diabetes mellitus and its influence on reactivity of blood vessels. In: Davis W, ed. The microcirculation in diabetes. Basel: Karger, 1979; 118-50. 6. McNair P, Christiansen C, Madsbad S, et al. Hypomagnesema, a risk factor in diabetic retinopathy. Diabetes 1978; 27: 1075-77. 7. Foster HD. Reducing cancer mortality: a geographical perspective. West Geogr Ser 1986; 23: 29-37. L, Laor A, Kitzes R. Reversible retinal vasospasm
in magnesium-treated hypertension despite no significant change in blood pressure Magnesium 1984; 3:
8. Cohen
159-63.
CAMPYLOBACTER PYLORI AND PEPTIC ULCER DISEASE
SiR,—The association between Campylobacter pylori and peptic ulcer disease appears stronger for duodenal than for gastric ulceration in that virtually all duodenal ulcer patients have C pylori positive antral gastritis whereas about 30 % of gastric ulcer patients are consistently C pylori negative. The significance of this finding in relation to the aetiology of gastric ulcer is at present unclear and
negative. No rheumatoid factor antibodies
were
detected.
or antinuclear or anti-DNA Antibodies against Toxoplasma, influenza and parainfluenza virus,
adenovirus, cytomegalovirus, respiratory syncytial virus, Mycoplasma pneumoniae, herpes simplex virus, Chlamydia psittaci, and Leptospira were not detected in
repeated serological investigations. HBs and HBe antigen (HbeAg) were negative; HBs antibodies were positive. 3 months after the first boost, after healing of the uveitis, the patient received the third dose of hevac B, against our advice. 4 days later she had the same symptoms as after the first boost, and bilateral
posterior uveitis was diagnosed again. No abnormal clinical and laboratory findings were found. Tests for rheumatoid factors and for antibodies against nuclei, mitochondria, and DNA were negative. The same antibodies tested after the first uveitis episode were again undetectable. Furthermore, no HIV antibody was found. HBsA was negative with an increased titre of HBs antibodies. HBeA and hepatitis B core antibodies were negative. Lymphocyte transformation tests (3H-thymidine incorporation) showed stimulated lymphocyte transformation by the vaccine. Similar results were observed in two other nurses immunised at the time with the same lot of vaccine. This is the first report of uveitis after hepatitis B vaccination. The causal relation with vaccination was shown by the re-exposure to the vaccine and renewed development of the eye disease. Bilateral uveitis occurred after both immunisations within a similar time, while known causes for uveitis could be excluded. The formation and peripheral deposition of immune complexes with complement activation is a major pathogenic mechanism in the development of uveitis in several infectious and systemic diseases.2 In our case, an immune complex disease was supported by the typical time interval of 3-4 days after antigen exposure while a cell-mediated immune response remained doubtful according to the results of the lymphocyte stimulation tests. Immune complex diseases such as cryoglobulinaemia and glomerulonephritis can be observed during chronic hepatitis B infection.3 The still unproven possibility that the hepatitis B virus could cause uveitis is suggested by the higher frequency of detectable HBsA and HBs antibodies in the blood of patients with uveitis,"and by a uveitis case with hepatitis B infection. We would suggest that the surface antigen of the vaccine and HBs antibodies of the immune response after vaccination formed immune complexes which initiated bilateral uveitis in our case. Thus, the surface antigen of the hepatitis virus could be responsible for the development of uveitis both after vaccination with HBsAg and during the course of hepatitis B infection. same
Outpatient Clinic and Division of Gastroenterology,
University Hospital, CH-4031 Basel, Switzerland
M. FRIED D. CONEN M. CONZELMANN E. STEINEMANN
1. Anonymous. The safety of hepatius B virus vaccine. MMWR 1983; 32: 134-36. 2. Rahi AHS, Holborow EJ, Perkins ES, Gungen YY, Dinning WJ. Immunological investigations in uveitis. Trans Ophthalmol Soc UK 1976; 96: 113. 3. London WT. Hepatitis B virus and antigen-antibody complex diseases. N Engl J Med 1977; 26: 1528-29. 4. Grob PJ, Martenet AC, Witmer R. Nonspecific immune parameters and hepatitis B antigens in patients with uveitis. Mod Probl Ophthalmol 1976; 16: 254-58. 5. Murray PI, Prasad J, Rahi AH. Status of hepatitis B virus in the aetiology of uveitis in Great Britain. Br J Ophthalmol 1983; 67: 685-87. 6. Farthing CF, Howard RS, Thin RN Papillitis and hepatitis B. Br Med J 1986; 292: 1712.
DETOXIFICATION OF PERTUSSIS VACCINES
SIR,-Dr Cameron (June 20, p 1427) does not refer to much of recent discussion about whole cell pertussis vaccines and their replacement by acellular vaccines. The presence in whole cell vaccines of histamine-sensitising factor (HSF) and lymphocytosispromoting factor (LPF) activities, now known to be properties of pertussis toxin,’ has been recognised for years. So too has the link between HSF activity and vaccine potency;’ indeed a small amount of active pertussis toxin will greatly enhance the potency of a variety of preparations in the intracerebral protection test.3 This has been a major problem in the development of acellular pertussis vaccines,
the
for which the aim has been to detoxify the toxin as completely as possible, precluding the use of the conventional potency assay. The need for thorough and irreversible detoxification follows from the recognition that this toxin has the potential to affect many physiological systems and might cause major reactions within the central nervous system. The precise mechanisms whereby this might happen, the dose of active pertussis toxin needed, and the involvement of other factors are all areas of conjecture. Agents used to detoxify pertussis toxin include formaldehyde and glutaraldehyde, which are well-tried for other bacterial toxins. However, the many variables in methodology can lead to products differing with regard to completeness of detoxification and stability. One cannot simply extrapolate from experience with other toxins because of differences in structure, (and hence reactivity with the detoxifying agent), molecular mechanism of action, and purity. Completeness of detoxification is usually assayed by the most sensitive
tests
available-ie, histamine sensitisation of mice and
clumping of Chinese hamster ovary (CHO) cells. Reversion to toxicity can be tested by incubating a vaccine for a long time at 4-37°C and then reassaying for active toxin. For the acellular pertussis vaccine developed at this centre, it is a requirement that active pertussin toxin should not be detectable in the vaccine before or after such incubations. Any acellular vaccine containing detoxified pertussis toxin should similarly be shown to be as completely and irreversibly detoxified as possible. In our experience whole cell vaccines fail this requirement since active toxin is readily detected by the histamine sensitisation test and, in contrast to Cameron’s findings, by the CHO cell assay also. The pertussin toxin content of whole cell vaccine in our previous. report’ was a crude estimate measured as LPF in mice; the content of inactive toxin could not be assessed. We now know that the ELISA for pertussis toxin does not work after this antigen has been subjected to the rigorous detoxification procedures used for acellular vaccines. Despite this apparent loss of ELISA antigenicity, the detoxified substance is a potent immunogen, giving rise to toxin-neutralising antibodies.5 In the future, inactive pertussin toxin or fragments thereof will probably be produced by techniques of molecular genetics or peptide synthesis, and chemical detoxification will become unnecessary. For the present, however, the procedures used ensure irreversible detoxification. This, together with the reduced endotoxin content, enables acellular vaccines to contain higher levels of toxin per dose (eg, the CAMR vaccine contains 10 Jlg detoxified pertussis toxin per dose besides 10 ng each of filamentous haemagglutinin and agglutinogens). Consequently, enhanced levels of serum antibody to PT are induced in comparison with the whole cell vaccine and this may allow a reduction in the number of doses required to induce full immunity.6 Experimental Pathology and Vaccine Research and Production Laboratories, Public Health Laboratory Service, Centre for Applied Microbiology and Research, Porton Down, Salisbury, Wiltshire SP4 0JG
L. A. E. ASHWORTH A. ROBINSON
JJ, Arai H, Bergman RK, Sadowski PL. Biological activities of crystalline pertussigen from Bordetella pertussis. Infect Immun 1981; 33: 820-26. 2. Pittman M. Comparison of the histamine-sensitising property with the protective activity of pertussis vaccines for mice. J Infect Dis 1951; 89: 300-04. 3. Robinson A, Irons LI. Synergistic effect of Bordetella pertussis lymphocytosis promoting factor on protective activities of isolated Bordetella antigens in mice. Infect Immun 1983; 40: 523-48. 4. Ashworth LAE, Robinson A, Irons LI, Morgan CP, Isaacs D. Antigens in whooping cough vaccine and antibody levels induced by vaccination of children. Lancet 1983; 1. Munoz
ii: 878-81. 5. Rutter DA, Ashworth LAE, Day A, Funnell S, Lovell F, Robinson A Tnal ofa new acellular pertussis vaccine in healthy adult volunteers. Vaccine (in press). 6. Olin P. Clinical results obtained to date in the Swedish trials. In. Workshop on acellular pertussis vaccines (sponsored by Interagency Group to Monitor Vaccine Development, Production and Usages, Bethesda, Maryland, September 1986): 106-10.
CRYPTOSPORIDIUM AND DRINKING WATER
SIR,-We read with interest the speculations on water-borne infection presented by Isaac-Renton and Cryptosporidium colleagues. Suspected water-borne cryptosporidiosis has been reported previously. 2,3
633 Sheffield area we observed a peak in human in April to October, 1986; such a peak was not observed in 1985 (or, so far, in 1987). Extensive epidemiological investigations failed to find a common source of food or milk or a consistent history of animal contact. However, of 104 patients with cryptosporidiosis, 84 (81 %) drank water supplied from the same reservoir complex. Use of a modified Ziehl-Neelsen staining technique4 and a monoclonal immunofluorescence tests revealed Cryptosporidium oocysts in faecal samples from cattle on farms adjoining the reservoir area, in the deposit from membrane-filtered surface water from the reservoir and from- streams feeding it, and in the intestinal contents of five apparently healthy brown trout (Salmo trutta) caught from the reservoir. Cattle are a well-documented source of Cryptosporidium oocysts.6,7 Contamination of the reservoir water from this source most probably happened via surface run-off after heavy rain. Reports of cryptosporidiosis in fish are uncommon ;8 such a finding confirms the widespread presence of Cryptosporidium in the aquatic environment. Cryptosporidium oocysts may not be effectively removed by normal water filtration methods;l they are resistant to many disinfectants9,10 and probably to routine water chlorination. Water-borne spread of Cryptosporidium is a possible, though as yet unproven, explanation for the peak in human cryptosporidiosis in the Sheffield area. In
the
cryptosporidiosis
We thank Mr D. Smith and Mr S. King of the Yorkshire Water Authority, and Mr F. G. Clegg of the Veterinary Investigation Centre, Sutton Bonnington, Loughborough, for their help. Public Health
Laboratory,
Northern General Hospital, Sheffield S5 7AU
BARBARA A. RUSH P. A. CHAPMAN
Environment Health Department, Sheffield
R. W. INESON
1. Isaac-Renton JL, Fogel D, Stibbs HH, Onngerth JE. Giardia and
Cryptosporidium in drinking water. Lancet 1987; i: 973-74. 2. Jokipii L, Pohjola S, Jokipii AMM. Cryptosporidium: a frequent finding in patients with gastrointestinal symptoms. Lancet 1983; ii: 358-61. 3. D’Antonio RG, Winnn RE, Taylor JP, et al. A waterborne outbreak of cryptosporidiosis in normal hosts. Ann Intern Med 1985; 103: 886-88. 4. Garcia LS, Brewer TC, Bruckner DA, Shimizu RY. Acid fast staining of Cryptosporidium from human faecal specimens. Clin Microbiol Newslett 1983; 5: 60-61. 5. McLauchlin
J, Casemore DP, Harrison DP, Gerson PJ, Samuel D, Taylor AG. Identification of Cryptosporidium oocysts by monoclonal antibody. Lancet 1987; i: 51 6. Angus KW. Cryptosporidiosis in man, domestic animals and birds: a review. J Roy Soc Med 1983; 76: 62-70. 7. Tzipori S. Cryptosporidium in animals and humans. Microbiol Rev 1983; 47: 84-96. 8. Hooveer DM, Hoerr FJ, Carlton WW, Hinsman EJ, Ferguson HW. Enteric cryptosporidiosis in a naso tang, Naso lituratus Bloch and Schneider. J Fish Dis 1981; 4: 425-28. 9. Angus KW, Sherwood D, Hutchinson G, Campbell I. Evaluation of the effect of two aldehyde-based disinfectants on the infectivity of faecal cryptosporidia for mice. Res Vet Sci 1982; 33: 379-81. 10. Campbell I, Tzipon S, Hutchinson G. Effect of disinfectants on survival of Cryptosporidium oocysts. Vet Rec 1982; 111: 414-15.
DIABETES MELLITUS AND LOW ENVIRONMENTAL MAGNESIUM LEVELS
S1R,-Chronic diabetes mellitus is associated with both low magnesium levels and serum hypomagnesaemia.1Indeed hypomagnesaemia even occurs in diabetic children,3in whom it is accompanied by significant changes in vascular reactivity. Despite the use of insulin, the incidence of high blood pressure in chronic tissue
diabetic patients varies between 40 and 80%.5 McNair et al6 have also shown that, in some diabetic patients, the degree of diabetic retinopathy is inversely related to the level of hypomagnesaemia. They therefore concluded that hypomagnesaemia is a risk factor in the development and progress of retinopathy. Similarly, Ewald et al3 have demonstrated that the degree of hypomagnesaemia in 27 children was positively correlated with future long-term diabetic
complications. The evidence therefore suggests that many of the problems associated with diabetes mellitus are linked to tissue and serum magnesium deficiencies. If so, one might anticipate that mortality from this disease would be lower in magnesium-enriched environments, which provide increased dietary levels of this element through drinking water and locally grown foods. To test
this hypothesis, I used Pearson correlation coefficients to compare the spatial distribution of diabetes mellitus mortality rates for the year 1980 in the USA with 221 climatic, hydrological, geological, social, and economic variables’ at the state level. I found that diabetes mortality was negatively correlated with both very high soil calcium (r = - 0-60742) and very high soil magnesium (r 0-56342). In contrast, positive correlations were found with the degree to which the state had been strip-mined (r 0-61291) and to the volume of industrial water withdrawals (r 0-60544) (p for all four correlations 0 0001). Stepwise multiple regression produced the following threevariable model, which could explain 64-2% of the variance = —
=
=
=
involved:
Mortality from diabetes mellitus 15-308 + (7-390 x En39) - (0-0310 x PVLB) - (0-0624 x PVHMg), where En39 is the percentage of the state disturbed by strip-mining (largely for coal), PVLB is the percentage of the state with soils that are very deficient in boron, and PVHMg is the percentage of the state with soils that are very rich in magnesium. Whilst co-linearity may be a problem in such stepwise regression, it is clear that a considerable portion of the diabetes mellitus mortality pattern in the USA can be explained in terms of soil magnesium variations. To explore the apparent relation further, Canadian agestandardised diabetes mortality rates for 1966-76 were compared with drinking-water analysis from 2633 locations. Mortality data =
available for both males and females from 258 electoral districts. There was a negative correlation between magnesium concentrations in drinking water and mortality from diabetes mellitus in males (r = - 0-20265) and females (r = - 0’23226). Although negative correlations also occurred between diabetes and calcium, these were lower: r==-012230 (p=00009) and r 0- 16780, respectively (p = 0-0001 unless otherwise stated). These analyses show that, in both the USA and Canada, mortality from diabetes mellitus tends to be increased where environmental magnesium and calcium levels are lowered-ie, in soft-water areas. This link between environmental magnesium, hypomagnesaemia, and diabetes mellitus is of more than academic interest. Cohen et al,8 for example, have reported that 8 young, diabetic hypomagnesaemic patients, treated with 750 mg magnesium oxide per day for three months, had complete reversal of the retinal vascular changes associated with high-renin essential hypertension. Normal serum magnesium levels were also restored. The value of treating diabetics with a magnesium supplement as well as insulin would therefore appear to warrant further study.
were
=
-
Department of Geography, University of Victoria, PO Box 1700, Victoria, British Columbia, Canada V8W 2Y2
HAROLD D. FOSTER
1. Aikawa JK.
Magnesium. Its biological significance. Boca Ratan, Florida: CRC Press, 1981. 2. Altura BC, Altura BT. New perspectives on the role of magnesium in the pathophysiology of the cardiovascular system I: Clinical aspects. Magnesium 1985; 4: 226-44. 3. Ewald U, Gebre-Medhin M, Tuvemo I. Hypomagnesaemia in diabetic children. Acta Paediatr Scand 1983; 72: 367-71. 4. Ewald U, Tuvemo T. Reduced vascular reactivity in diabetic children and its relation to diabetic control. Acta Paediatr Scand 1985, 74: 77-84. 5. Altura BM, Halevy S, Turlapaty PDMV. Vascular smooth muscle m diabetes mellitus and its influence on reactivity of blood vessels. In: Davis W, ed. The microcirculation in diabetes. Basel: Karger, 1979; 118-50. 6. McNair P, Christiansen C, Madsbad S, et al. Hypomagnesema, a risk factor in diabetic retinopathy. Diabetes 1978; 27: 1075-77. 7. Foster HD. Reducing cancer mortality: a geographical perspective. West Geogr Ser 1986; 23: 29-37. L, Laor A, Kitzes R. Reversible retinal vasospasm
in magnesium-treated hypertension despite no significant change in blood pressure Magnesium 1984; 3:
8. Cohen
159-63.
CAMPYLOBACTER PYLORI AND PEPTIC ULCER DISEASE
SiR,—The association between Campylobacter pylori and peptic ulcer disease appears stronger for duodenal than for gastric ulceration in that virtually all duodenal ulcer patients have C pylori positive antral gastritis whereas about 30 % of gastric ulcer patients are consistently C pylori negative. The significance of this finding in relation to the aetiology of gastric ulcer is at present unclear and