HYDATID ERADICATION

Otago Daily Times, Issue 23940, 16 October 1939, Page 9

HYDATID ERADICATION

LESSON FROM HYDROPHOBIA

By Dr E. W. Bennett

IX It is a curious fact that until about a year ago the most common answer to the question What disease is caught from dogs was “hydrophobia.” This is all the more remarkable in that this disease has fortunately never occurred in either Australia or New Zealand. Perhaps the reason why so many know something about it is that the effects of the disease on dog and man alike are spectacular enough to have led to mention of it in novels and historical works. “ Dogs suffer from madness,” said Aristotle, 23 centuries ago, “ that puts them in a state of fury, and all animals which they bite when in this condition become likewise attacked by madness.” Many other classic authors refer to it, but the occurrence in human beings was not mentioned till thfe time of Celsius, at the beginning of the Christian era. It was Celsius who invented the inappropriate name of hydrophobia, which means “fear of water.” Since no such fear exists, there are grounds for preferring the shorter modem name, rabies. There has been a long succession of epidemics, and one and a-half centuries ago the disease was widely spread throughout Europe. Many prizes were offered for a cure, but naturally, as with distemper and so many other maladies of man and animals, no cure was likely to be found until the cause had become.known, and in such a search for the_ origin the clue was obtained by experimenting on animals. It was not difficult to show by this means that the masses of frothy saliva that appear in the mouth are highly infective, sn that the bite of a rabid dog or wolf was an effective means of conveving the virus to new victims. In this there is a contrast with hydatid disease, for the mere presence of a dog infected with hydatid worms is sufficient to constitute a menace from the innumerable hydatid eggs spread by him. But in both cases the trouble depends on an infection with living parasites; fits and madness in New Zealand dogs are not due to rabies, because the virus is not present in the country. In any case dogs infected with the virus do not always become mad; some remain quiet and affectionate just as some inebriates become fighting drunk and others become sentimental. In the case of infection with hydatid worms there is normally no effect either on the appearance or on the behaviour of the dog. The glossy and carefully groomed pet and the vagrant cur can equally be spreaders of hydatids. There are many other points of contrast. For example, dogs do not have hydatid disease at all, in that their livers and lungs do not become riddled with parasitic growths: they are the incubators and spreaders of hydatids, but not themselves victims of it. In the case of rabies the dog suffers from exactly the same form of malady as man, and spreads the disease because dogs are especially prone to it, and because their habit of biting when rabid provides means of spreading the virus further. Another difference is that rabies is a fatal disease, and therefore always tends to eradicate itself. It would in fact speedily do so if mqst rabid animals were not prone to bite with especial viciousness, and this fact provides a means of ensuring the eradication of the disease, which has now been effected in many countries. If hydatid worms were fatal to dogs the disease would soon disappear of itself; but since they usually show not the least outward trace it is necessary that all dogs be dosed with arecohne, even though it is only a percentage that are actually infected. In the more progressive European countries rabies has been eradicated long ago. Denmark, Sweden and Norway have been free from it for over half a century; in German-speaking countries there has been a great decrease, but there are about 500 rabid dogs a year and some other rabid animals, these being all recorded from near the boundaries of countries that have not taken measures to suppress the disease. It is noteworthy that the countries which eradicated it earliest and most easily were island or peninsulas: the quarantine regulations, which require an imported dog to be kept under supervision for six months, have kept Australia and New Zealand free. The same advantages of an island country apply to hydatid disease, and improve our chance of getting rid of it and thereafter keeping it out. Careless neighbouring countries .have always been a hindrance in the control of rabies, and this is eminently so in the case of hydatids, not only in the case of neighbouring countries, but also on farms, for infected dogs belonging to one owner may endanger the stock and family of a neighbour who keeps his dogs fjee from parasites.

It is clear from the above that the method of controlling rabies is by muzzling dogs. No treatment is used, and in an enlightened country no option is given whether a dog is to be muzzled or not. This universal action is most desirable in the case of hydatid disease also, but there is an advantage in the control of rabies in that it is obvious at a glance whether a dog is muzzled or not, and the legislative requirements are accordingly easy to enforce; whereas it is no more possible to tell by looking at a dog whether he has had arecoline than it is to know whether he has been misused through being allowed to feed on livers or lungs. Very illuminating is the record of the effects of the legislation in England. In 1889 there were 312 cases in dogs and 30 in man; in the following year compulsory muzzling was introduced, and the figures fell at once to 129 and 8 respectively. In the next few years they dropped to 38 and 4, but there was an indignant opposition from an unenlightened section of the public, who protested against hardship and cruelty to dumb animals, and endea- 1 voured to maintain that muzzling was a cause instead of a means of eradicating the disease. This sort of nonsense has been .a hindrance in the eradication of hydatid disease, and, in fact, can always be expected from an ignorant minority who claim to know better. In this case the clamour was so great that in 1893 it was weakly decided, in spite of the encouraging progress results, to relax the ordinance. The effect was immediate—in 1894 the figures rose to 248 cases in dogs and 13 in human beings, and in the following year the totals were 672 and 20. Muzzling was again enforced, whether cruel to dogs or not, with the result that there was again a decline, this time to zero level. There have been no cases in human beings in England since 1898, but since a few cases were still occurring among dogs at that date, it was too early to claim that the disease had been eradicated, and when a petition was presented to the Government to put an end t 0 such an allegedly cruel practice as muzzling dogs, the petitioners were quickly sent about their business. It is scarcely worth the trouble to discuss with such people whether the necessity of using muzzles is a greater or less evil than the perpetuation of a fatal and unnecessary disease. Since 1903 there have been no cases among dogs in England, except that during the last war there were infringements of the quarantine regulations and dogs reached England from abroad by aeroplane. In August, 1918, hydrophobia had again appeared, but it was quickly suppressed and is now extinct in the Home Country. As a result both of this success and of the rarity of hydatid disease in England, dogs are safe pets in that country, and there is no need for muzzling or universal dosing. When hydatid disease is eradicated in New Zealand universal dosing / will similarly become unnecessary, and it will be safe to let dogs eat livers and lungs of sheep and cattle. The precautions still essential in this country are only temporary, until the menace has become a thing of the past. The eradication of rabies shows clearly what can be done if it is decided to have it done. But the lesson from such an experiment in health protection is not always remembered. There will always be faddists and humanitarians, with their paltry objections resulting from a false perspective, and there will always be a defaulting faction as long as each owner of a dog is allowed to decide whether he should take action or not. In India no action is taken; the reason usually given is that the country is too vast and there are too many infected wild animals, but the main reason is that the community is illiterate and incapable of self-help. It remains to be seen whether this has to be said also of New Zealand with respect to hydatids. In Palestine a vigorous policy of destroying jackals and other pests is in force, whether the populace approve or not; they are likewise illiterate, but even that difficulty can be overcome by compulsory legislation and by sanitary policing. Again it remains to be seen whether New Zealand can eradicate hydatids without recourse to compulsion. One would like to think that such is unnecessary, but all depends on the degree of enlightenment, not of the most responsible members of the community, or even of the average, but of the least capable. Compulsory dosing of dogs and the prohibition of scavenging and feeding on offal, would protect the whole community and our farm animals against the anti-social negligence of those whose standards of hygiene approach Asiatic levels.