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Studies on Endemic and Experimental Goitre
- C. E. Hercus, H. D. Purves
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- Journal:
- Journal of Hygiene / Volume 36 / Issue 2 / June 1936
- Published online by Cambridge University Press:
- 15 May 2009, pp. 182-203
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1. Some improvements in the determination of small quantities of iodine in biological substances are described.
2. The thesis that a low iodine intake is prerequisite for goitre production is supported.
3. A survey of determinations by various authors of the daily urinary iodine excretion in goitrous and non-goitrous regions leads to the conclusion that the critical level of iodine intake sufficient to suppress goitre is between 120 and 160γ per day.
4. Determinations of urinary iodine excretion in New Zealand and in the non-goitrous islands of Samoa are presented which show that in the parts of New Zealand investigated the iodine intake is at a low or goitrous level.
5. The result in New Plymouth, Taranaki, shows that a high content of iodine in the soil does not necessarily assure an adequate iodine intake.
6. The progress of prophylaxis by iodised salt in New Zealand is reviewed, and from consumption data it is concluded that iodised salt constitutes approximately only 30 per cent, of the domestic salt consumption of New Zealand.
7. To ensure a more general use of iodised salt it is recommended that the regulations be amended to provide that:
(a) Ordinary domestic salt shall be iodised.
(b) Non-iodised salt shall be sold only in packages labelled “Non-iodised” and with the addition “ The use of this salt exposes the user to the risk of developing goitre”.
8. The results obtained hitherto with the use of iodised salt are briefly reviewed and attention drawn to some apparent failures even when iodised salt has been used for all domestic purposes. These failures are attributed to the standard for iodised salt being too low.
9. It is concluded that for New Zealand a supplementation of at least 100γ per day is necessary to afford complete protection against goitre.
10. To provide the necessary amount of supplementation the iodine content of iodised salt in New Zealand requires to be raised. We recommend therefore that either
(a) If the domestic salt only is to be iodised the standard be fixed at from 5 to 6 parts of potassium iodide (KI) per 250,000 of salt, or
(b) If iodised salt is to be used in the manufacture of bread, butter, bacon and other salted foods, the standard be fixed at from 3 to 4 parts of potassium iodide (KI) per 250,000 of salt.
11. In New Zealand cabbage has not shown any marked goitrogenic activity as tested on rabbits.
12. Turnip roots showed sporadically a goitrogenic activity comparable with that found for the most active samples of cabbage in other countries.
13. In tests of Brassica seeds on rats, goitrogenic activity was found in rape seed, cabbage seed, steamed white mustard seed, and steamed black mustard seed.
14. The activity of rape seed was destroyed by steaming.
We have pleasure in acknowledging the financial help which we have received from the Sir John Roberts Endowment for Medical Research, from the Sir H. L. Ferguson Fund and from the Honorary Staff of the Dunedin Hospital, and for the co-operation of a large number of our colleagues in New Zealand and Samoa in the collection of specimens.
Miscellaneous Studies on the Iodine and Goitre Problem in New Zealand
- C. E. Hercus, H. A. A. Aitken
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- Journal:
- Journal of Hygiene / Volume 33 / Issue 1 / January 1933
- Published online by Cambridge University Press:
- 15 May 2009, pp. 55-79
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1. Methods for the estimation of iodine in natural products are described.
2. Common sea weeds on the Pacific coast of Otago have an iodine content of the same order as similar species on the Pacific coast of British Columbia.
3. In Cystophora retroflexa, which contains over 0·1 per cent, of iodine, 70–80 per cent, of the iodine appears to be in inorganic or loosely bound combination. Precipitation and colour tests indicate that di-iodotyrosine is also present.
4. Observations are recorded of the iodine content of kelp-feeding and other fish.
5. Administration of anaesthetics produces fluctuations in the concentration of blood iodine in rabbits, the effect persisting after removal of the thyroid gland. Experiments in vitro suggest that only in the case of inorganic iodine could a redistribution of iodine between tissues and serum be brought about by the direct action of anaesthetics.
6. New Zealand cabbage possesses goitrigenous properties for rabbits but in a much smaller degree than American cabbage.
7. The urinary excretion of Samoans is compared with that of inhabitants of Christchurch Mental Hospital.
8. The incidence and course of development of goitre at Christchurch Mental Hospital is discussed.
9. Values are given for the iodine content of Otago pigs' thyroids.
An Epidemiological Study of Diphtheria in a remote New Zealand Community
- C. E. Hercus, R. A. Shore, H. E. Barrett, J. H. North
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- Journal:
- Journal of Hygiene / Volume 29 / Issue 3 / December 1929
- Published online by Cambridge University Press:
- 15 May 2009, pp. 243-258
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1. The incidence produced during 1926 by two epidemics of diphtheria, in a remote and unsalted country district, was equivalent to 30 years of the London endemic morbidity.
2. The cases arose in two distinct groups. An autumn outbreak with a definite concentration of infection on the school age, and probably disseminated by droplet infection, followed by an epidemic in the succeeding spring which was more severe, probably milk-borne, and in which the frequency of cases was higher among infants and adults than school children.
3. The effect of a long drive over bad roads caused a deterioration of the diluted toxin which was used for a Schick test investigation. The use of this toxin led at first to false conclusions regarding the immunity of the children, since it only caused reactions in the most susceptible members of the community.
4. As a result of retesting with a fully potent toxin it was estimated that the figure of 40 per cent. susceptible which was found with the weak toxin would have been about 80, if full strength toxin had been used.
5. The attempt to immunise actively those children who had reacted to the weak Schick toxin was found to have failed in 72 per cent. of a group which was retested 7 months later. The prophylactic course was identical with one which had succeeded in inducing Schick immunity, within 4 months, in 100 per cent. of the susceptible children in the Dunedin orphanages.
6. The slow rate of immunisation at Kaitangata is attributed to two causes, (a) the low original herd immunity of the district, (b) the selection by the weak toxin of only the most sensitive reactors which were almost certainly the most “unresponsive” members of the total Schick positive population.
7. By a comparison of the rate of response to a small dose of toxin-anti-toxin mixture, in those positive Schick reactors (a) who had, and (b) who had not, received previous prophylactic injections, it was shown that the principle of “primary and secondary” antigenic stimuli held good for human subjects, as well as for experimental animals.
8. Careful examination of the known data led to the conclusion that the air-borne autumn epidemic had increased the herd immunity of the population, in spite of the fact that the subsequent milk-borne spring outbreak produced as high a morbidity and a more severe type of diphtheria.
9. The practical lessons which may be learnt from this study are: (a) That unless a special buffered diluent is used, the toxin used for Schick testing must be freshly diluted near the place where it is to be used, (b) Active immunisation of remote unsalted communities against diphtheria requires more time, and more intensive courses of prophylactic, than areas where diphtheria has been endemic for some years, (c) In such places with a low original herd immunity, it is essential, even more than in endemic centres, never to omit retesting those who have been inoculated, in order to be certain that any attempt made to induce active immunity to diphtheria may be successful. (d) Estimations of the relative efficiency of diphtheria prophylactics, which are based on the rapidity with which samples of children become immune, are worthless unless all the observations have been made in the same environment on groups having the same original herd immunity, (e) An immunity, good enough to withstand droplet infection in a day school environment, may be broken down by massive doses of diphtheria bacilli in milk.
10. The study of outbreaks of disease in communities which are not too large to prevent a complete supervision of the whole population and environment, enable one to visualise imaginary mechanisms of infection very much more easily than in large populous areas, where so many more factors have to be left unexamined, or remain unsuspected. The hypotheses, perhaps better termed surmises, which the facts suggest, are only intended to be purely tentative and temporary. Their practical value is that they indicate to the investigator a plan of campaign and suggest what to look for, in the lucky event of his ever again meeting with a similar combination of circumstances. In epidemiology in general, as illustrated by this particular instance, opportunities arise and pass, often never to recur, and much is missed, or left undone that might have been done, if only the knowledge and hints gained during the passage of the epidemic itself had been known before its advent.
The Iodine Content of Foods, Manures and Animal Products in Relation to the Prophylaxis of Endemic Goitre in New Zealand: Studies from the Universiaaty of Otago, New Zealand
- C. E. Hercus, K. C. Roberts
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- Journal:
- Journal of Hygiene / Volume 26 / Issue 1 / March 1927
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- 15 May 2009, pp. 49-83
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The correlation of high goitre incidence in New Zealand with low soil iodine having been established previously, the distribution of iodine in its relationship to the goitre problem is further considered in this study. The method of analysis used throughout has been that of Th. V. Fellenberg, with certain minor modifications. The findings are summarised as follows:
1. In a general survey of the iodine content of foodstuffs in New Zealand, it has been shown that the foods richest in iodine, arranged in descending order of iodine content, are edible seaweed, sea fish, eggs, wholemeal cereal products, leafy vegetables and milk. Refined cereal products, root vegetables, and fruits are shown to be of low iodine content. Dried foods contain more iodine than the corresponding fresh foods.
2. A comparative study of the iodine content of foodstuffs from goitrous and non-goitrous districts establishes the fact that the soil-iodine is accurately reflected in the food-iodine.
3. The difference in the daily iodine intake in the food supply of typical goitrous and non-goitrous districts is calculated to be 14·35 micrograms.
4. The iodine content of certain vegetables and animal foods is shown to present a well-marked seasonal variation. The maximum iodine content of vegetable matter is reached in the late autumn and winter when growth is at a minimum. In the case of eggs the maximum is reached in summer, in milk in the spring. In the latter case calving and lactation are shown to be disturbing factors of importance.
5. Cooking is shown to have little effect on the reduction of the iodine content of root vegetables, seaweed, fish and bread, but to reduce the content of green vegetables by about two-thirds.
6. Commercial salt is shown to be an unreliable source of iodine supply, the majority being practically iodine-free.
7. Tobacco smoke is a negligible source of iodine supply.
8. The iodine content of the artificial manures commonly used in New Zealand is determined, and their probable effect on the content of crops is calculated.
9. The iodine adsorptive powers of different types of soils is estimated experimentally. Loam is shown to have marked retentive powers for soluble iodides. In clay the retention is less and in sand nil.
10. Experimental studies on the influence of iodine-rich manures on plant life are presented.
11. A well-defined relationship is shown to exist between goitre incidence and iodine excretion in the urine.
12. The iodine content of human milk in the goitrous woman is shown to be lower than in the non-goitrous, and a relationship is shown to exist between the amount of iodine excreted in the urine and milk during lactation.
13. The flesh of fish is shown to vary in iodine content according to its “iodine environment.”
14. Small amounts of potassium iodide added to the diet of various animals is shown to increase the iodine content of the thyroid glands and of the food products.
15. Certain intestinal bacteria are studied in regard to their power of absorbing iodine from an alkaline medium rich in iodine with negative results.
16. Certain data with regard to the iodine content of the thyroid glands of various animals are submitted which suggest that certain animals can live on a lower iodine threshold than man without developing goitre.
Further Observations on the Occurrence of Iodine in Relation to Endemic Goitre in New Zealand and on Iodine Metabolism
- C. E. Hercus, H. A. A. Aitken, H. M. S. Thomson, G. H. Cox
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- Journal:
- Journal of Hygiene / Volume 31 / Issue 4 / October 1931
- Published online by Cambridge University Press:
- 15 May 2009, pp. 493-522
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1. Most artificial manures are found to have some effect in increasing the iodine content of crops, particularly superphosphate.
2. Marked differences are found between the iodine contents of Samoan and New Zealand foodstuffs corresponding to the non-goitrous condition of Samoa and the partial endemicity of New Zealand.
3. Investigation of the dietaries of fifteen residential institutions showed that improvement in provision of iodine was necessary in many cases by using fish at least twice a week, raising the daily ration of milk to 1 pint per head, and employing iodised salt for table and culinary purposes.
4. Dietetic experiments indicate (i) that on a change of diet adjustment of iodine metabolism may take a considerable time, (ii) that iodised salt is most effective in promoting storage of iodine when associated with a meat diet.
5. Iodine excretion is found to decrease much more rapidly under fasting than on a diet very low in iodine.
6. Iodised salt has the effect of adjusting the excretion of goitrous adults to the normal non-goitrous value.
7. The iodine content of the blood is found to be lower than normal in cases of simple colloid and simple nodular goitre, though it may range from low to abnormally high in cases of Graves' disease. In all types of goitre the thyroid gland is low in iodine.
8. The ratio of thyroid iodine to total bodily iodine is about 12 per cent. in the case of the white rat under ordinary conditions, but the ratio is found to vary considerably with the iodine intake.
9. Great differences in the ratio of the weight of the thyroid gland to that of the whole body are found among different species of animals, the ratio being higher for the dog than for the monkey.
10. Variations in commercial samples of iodised salts are recorded and discussed.
11. Data are given in regard to the iodine and chlorine content of rainwater in different localities.
The Nutritional Status of Cook Islanders
- S. Faine, C. E. Hercus
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- Journal:
- British Journal of Nutrition / Volume 5 / Issue 3 / December 1951
- Published online by Cambridge University Press:
- 09 March 2007, pp. 327-343
- Print publication:
- December 1951
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