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    "source_title": "Encyclopaedia Britannica (1911)",
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    "chunk_id": "1911:diseases:a21def239b18",
    "title": "DISEASES",
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    "verified_text": "diseases, and little need be said about them here. they belong to the group of protozoa, and, as already explained, have a double cycle of existence: (1) a sexual cycle in the body of the mosquito, (2) an asexual cycle in the blood of human beings. they occupy and destroy the red corpuscles, converting the haemoglobin into melanin; they multiply in the blood by sporulation, and produce accessions of fever by the liberation of a toxin at the time of sporulation (ross). the number in the blood in an acute attack is reckoned by ross to be not less than 250 millions. a more general and practical interest attaches to the insects which act as their intermediate hosts. these mosquitoes or gnats--the terms are synonymous--belong to the family _culicidae_ and the genus _anopheles_, which was first classified by meigen in 1818. it has a wide geographical distribution, being found in europe (including england), asia minor, burma, straits settlements, java, china, formosa, egypt; west, south and central africa; australia, south america, west indies, united states and canada, but is generally confined to local centres in those countries. about fifty species are recognized at present. it is believed that all of them may serve as hosts of the parasite. the species best known in connexion with malaria are _a. maculipennis_ (europe and america), _a. funestus_ and _a. costales_ (africa). in colour _anopheles_ is usually brownish or slaty, but sometimes buff, and the thorax frequently has a dark stripe on each side. the wings in nearly all species have a dappled or speckled appearance, owing to the occurrence of blotches on the front margin and to the arrangement of the scales covering the veins in alternating light and dark patches (austen). the genus with which _anopheles_ is most likely to be confounded is _culex_, which is the commonest of all mosquitoes, has a world-wide distribution, and is generally a greedy blood-sucker. a distinctive feature is the position assumed in resting; _culex_ has a humpbacked attitude, while in _anopheles_ the proboscis, head and body are in a straight line, and in many species inclined at an angle to the wall, the tail sticking outwards. in the female of _culex_ the palpi are much shorter than the proboscis; in _anopheles_ they are of the same length. the wings in _culex_ have not the same dappled appearance. _anopheles_ is also a more slender insect, with a smaller head, narrower body and thinner legs. there are further differences in the other stages of life. mosquitoes go through four phases: (1) ovum, (2) larva, (3) nympha, (4) complete insect. the ova of _anopheles_ are tiny black rod-shaped objects, which are deposited on the water of natural puddles, ponds, or slowly moving streams, by preference those which are well supplied with vegetation; they float, singly or attached to other objects or clustered together in patterns. they can live in brackish and even in sea water. the larva has no breathing-tube, and floats horizontally at the surface, except when feeding; it does not frequent sewage or foul water. the ova of _culex_, on the other hand, are deposited in any stagnant water, including cesspools, drains, cisterns, or water collected in any vessel; they float in boat-shaped masses on the surface. the larva has a breathing-tube, and floats head downwards; when disturbed it wriggles to the bottom (christy). some observers maintain that _anopheles_ does not \"sing,\" like the common mosquito, and its bite is much less irritating. only the females suck blood; the act is believed to be necessary for fertilization and reproduction. _anopheles_ rarely bites by day, and then only in dark places. in the daytime \"the gorged females rest motionless on the walls and ceilings of rooms, choosing always the darkest situations for this purpose\" (austen). in temperate climates the impregnated females hibernate during the winter in houses, cellars, stables, the trunks of trees, &c., coming out to lay their eggs in the spring. the four phases are passed in thirty days in a favourable season, and consequently there are ordinarily four or five generations from april to september (celli). the most important question raised by the mosquito-parasitic theory of malaria is that of prevention. this may be considered under two heads: (1) individual prophylaxis; (2) administrative prevention on a large scale. prophylaxis. (1) in the first place, common sense suggests the avoidance, in malarious countries, of unhealthy situations, and particularly the neighbourhood of stagnant water. among elements of unhealthiness is next to be reckoned the proximity of native villages, the inhabitants of which are infected. in the tropics \"no european house should be located nearer to a native village than half a mile\" (manson), and, since children are almost universally infected, \"the presence of young natives in the house should be absolutely interdicted\" (manson). when unhealthy situations cannot be avoided, they may be rendered more healthy by destroying the breeding-grounds of mosquitoes in the neighbourhood. all puddles and collections of water should be filled in or drained; as a temporary expedient they may be treated with petroleum, which prevents the development of the larvae. when a place cannot be kept free from mosquitoes the house may be protected, as in the experiments in italy, by wire gauze at the doors and windows. the arrangement used for the entrance is a wire cage with double doors. failing such protection mosquito curtains should be used. mosquitoes in the house may be destroyed by the fumes of burning sulphur or tobacco smoke. according to the experiments of celli and casagrandi, these are the most effective culicides; when used in sufficient quantity they kill mosquitoes in one minute. the same authorities recommend a powder, composed of larvicide (an aniline substance), chrysanthemum flowers, and valerian root, to be burnt in bedrooms. anointing the skin with strong-smelling substances is of little use in the open air, but more effective in the house; turpentine appears to be the best. exposure at night should be avoided. all these prophylactic measures are directed against mosquitoes. there remains the question of protection against the parasite. chills are recognized as predisposing both to primary infection and to relapses, and malnutrition is also believed to increase susceptibility; both should therefore be avoided. then a certain amount of immunity may be acquired by the systematic use of quinine. manson recommends five to ten grains once or twice a week; ross recommends the same quantity every day before breakfast. there is some evidence that arsenic has a prophylactic effect. an experiment made on the railway staff at bovino, a highly malarious district on the adriatic, gave a striking result. the number of persons was 78, and they were divided into two equal groups of 39 each. one group was treated with arsenic, and of these 36 escaped altogether, while three had mild attacks; the remaining 39 who were not treated, all had fever. in a more extended experiment on 657 railwaymen 402 escaped. this was in 1889; but in spite of the encouraging results the use of arsenic does not appear to have made any further progress. experiments in immunizing by sero-therapeutic methods have not as yet met with success. administrative measures. (2) much attention has been directed in scientific circles to the possibility of \"stamping out\" epidemic malaria by administrative measures. the problem is one of great practical importance, especially to the british empire. there are no data for estimating the damage inflicted by malaria in the british colonies. it is, indeed, quite incalculable. in italy the annual mortality from this cause averages 15,000, which is estimated to represent two million cases of sickness and a consequent loss of several million francs. in british tropical possessions the bill is incomparably heavier. there is not only the heavy toll in life and health exacted from europeans, but the virtual closing of enormous tracts of productive country which would otherwise afford scope for british enterprise. the \"deadly\" climates, to which so much dread attaches, generally mean malaria, and the mastery of this disease would be equivalent to the addition of vast and valuable areas to the empire. the problem, therefore, is eminently one for the statesman and administrator. a solution may be sought in several directions, suggested by the facts already explained. the existence of the parasite is maintained by a vicious interchange between its alternate hosts, mosquitoes and man, each infecting the other. if the cycle be broken at any point the parasite must die out, assuming that it has no other origin or mode of existence. the most effective step would obviously be the extermination of the _anopheles_ mosquito. a great deal may be done towards this end by suppressing their breeding-places, which means the drying of the ground. it is a question for the engineer, and may require different methods in different circumstances. put comprehensively, it involves the control of the subsoil and surface waters by drainage, the regulation of rivers and floods, suitable agriculture, the clearing of forests or jungles, which tend to increase the rainfall and keep the ground swampy. the city of rome is an example of what can be done by drainage; situated in the midst of malaria, it is itself quite healthy. recent reports also show us how much may be done in infected districts. at ismailia malaria was reduced from 1551 cases in 1902 to 37 cases in 1905. the cost of operations amounted to an initial expenditure of 6.25 francs, and an annual expenditure of about 2.3 francs per head of the population. \"the results are due to mosquito reduction together with cinchonization.\" the following is a tabulated list of the cases. the population of ismailia is about 6000. +------------------+------+------+-------+------+------+--------+ | year | 1900 | 1901 | 1902* | 1903 | 1904 | 1905 | +------------------+------+------+-------+------+------+--------+ | cases of malaria | 2250 | 1990 | 1548 | 214 | 90 | 372[2] | +------------------+------+------+-------+------+------+--------+ * drainage works begun. klang and port swettenham are contiguous towns in the federated malay states, having a population of 4000 and a rainfall of 100 in. a year. at klang the expenditure has been £3100, with an annual expenditure of £270, devoted to clearing and draining 332 acres. at port swettenham £7000, with an annual upkeep of £240, has been devoted to treating 110 acres. in hong-kong similar measures were carried out, with the result that the hospital admissions for malaria diminished from 1294 in 1901, the year when operations were begun, to 419 in 1905. klang and port swettenham. +------------------+------+-------+------+------+------+------+ | year | 1900 | 1901* | 1902 | 1903 | 1904 | 1905 | +------------------+------+-------+------+------+------+------+ | cases of malaria | 510 | 610 | 199 | 69 | 32 | 23 | +------------------+------+-------+------+------+------+------+ * nearly all were relapses of previous infection. a systematic campaign for the destruction of breeding-places has been inaugurated in the british west african colonies, with encouraging results. the planting of eucalyptus trees is out of favour at present, but it appears to have been successful in portugal, not from any prophylactic virtues in the plant, but through the great absorption of moisture by its deep roots, which tends to dry the subsoil. treating the breeding-ponds with petroleum or similar preparations seems to be hardly applicable on a large scale, and in any case can only be a temporary expedient. h. ziemann advocates the destruction of mosquito larvae by the growing of such plants as the water-pest (_anacharis alsinatrum_) which covers the surface of the water and suffocates larvae and nymphae. short of suppressing mosquitoes, the parasitic cycle may theoretically be broken by preventing them from giving the infection to man or taking it from him. the means of accomplishing the former have been already pointed out, but they are obviously difficult to carry out on a large scale, particularly in native communities. it is one thing to protect individuals from mosquito bites, another to prevent the propagation of the parasite in a whole community. perhaps the converse is more feasible in some circumstances--that is to say, preventing mosquitoes from having access to malarial persons, and so propagating the parasite in themselves. it could be carried out where the infected persons are few, by isolating and protecting them, but not where many are infected, as in native villages. koch has suggested that the disinfection of malarial persons by quinine would have the desired effect, but other authorities of greater experience do not consider it practicable. in spite of the difficulties, however, there is no doubt that a great deal can be done to reduce, if not stamp out, malaria by the methods indicated, which should be applied according to circumstances. an encouraging example is afforded by the remarkable fact that malaria, which was once rife in certain districts of england, has now died out, although the _anopheles maculipennis_ mosquito still exists there. the parasitic cycle has been broken, and the insect is no longer infected. the suggested causes are (1) reduction of insects by drainage, (2) reduced population, (3) the use of quinine. sir patrick manson has suggested that the problem of stamping out malaria may be assisted by the discovery of some at present unknown factors. he has pointed out that certain areas and certain islands are entirely free from the disease, while neighbouring areas and islands are devastated. this immunity is apparently not due to the absence of favourable conditions, but rather to the presence of some inimical factor which prevents the development of the parasite. if this factor could be discovered it might be applied to the suppression of the disease in malarious localities. a few other points may be noted. the pathological changes in malaria are due to the deposition of melanin and the detritus of red corpuscles and haemoglobin, and to the congregation of parasites in certain sites (ross). in chronic cases the eventual effects are anaemia, melanosis, enlargement of the spleen and liver, and general cachexia. apparently the parasites may remain quiescent in the blood for years and may cause relapses by fresh sporulation. recent discoveries have done little or nothing for treatment. quinine still remains the one specific. in serious cases it should not be given in solid form, but in solution by the stomach, rectum, or--better--hypodermically (manson). according to ross, it should be given promptly, in sufficient doses (up to 30 grains), and should be continued for months. euquinine is by some preferred to quinine, but it is more expensive. nucleogen and aristochin have also been recommended instead of quinine. the nature of immunity is not known. some persons are naturally absolutely immune (celli), but this is rare; immunity is also sometimes acquired by infection, but as a rule persons once infected are more predisposed than others. races inhabiting malarious districts acquire a certain degree of resistance, no doubt through natural selection. children are much more susceptible than adults. _malaria in the lower vertebrates._--birds are subject to malaria, which is caused by blood parasites akin to those in man and having a similar life-history. two species, affecting different kinds of birds, have been identified. their alternate hosts are mosquitoes of the _culex_ genus. oxen, sheep, dogs, monkeys, bats, and probably horses also suffer from similar parasitic diseases. in the case of oxen the alternate host of the parasite is a special tick (smith and kilborne). in the other animals several parasites have been described by different observers, but the alternate hosts are not known. authorities.--celli, _malaria_; christy, _mosquitoes and malaria_; manson, _tropical diseases_; allbutt's _system of medicine_; ross, \"malaria,\" quain's _dictionary of medicine_, 3rd ed.; _the practitioner_, march, 1901 (malaria number); _lancet_ (sept. 29, 1907); _british medical journal_ (oct. 19, 1907); _indian medical gazette_ (february 1908). (a. sl.; h. l. h.) malatia (malatieh or aspuzu) the chief town of a sanjak of the same name in the mamuret el-aziz vilayet of asia minor, and a military station on the samsun-sivas-diarbekr road, altitude 2900 ft., situated about 10 m. s.w. of the junction of the tokhma su (med. kubakib) with the euphrates, near the south end of a fertile plain, and at the northern foot of the taurus. pop. about 30,000, including, besides many armenian christians, bodies of kurds and \"kizilbash.\" it is a wholly modern place, rebuilt since the earthquake of 1893, contains fine public buildings, and is noted for its fruit orchards. there are protestant (american) and roman catholic missions, and an armenian catholic archbishop has his seat here. eskishehr or old malatia (_melitene_), 5 m. n.e. and 3 m. from the great medieval bridge (kirkgeuz) over the tokhma su, is said to owe its present desolation largely to its occupation by hafiz pasha as his headquarters in 1838 before his advance to fight the disastrous battle of nizib with the egyptian, ibrahim. but it has still many inhabitants and large gardens and many ruinous mosques, baths, &c., relics of mansur's city. it was the residence of von moltke for some months, while attached to hafiz's army. the earliest site was possibly arslan tepe about 2 m. south of eskishehr were two \"hittite\" stelae, representing hunting scenes, now in the constantinople and paris museums, were found in 1894. in the time of strabo (xii. 537) there was no town in the district of melitene, which was reckoned part of cappadocia. under titus the place became the permanent station of the 12th (\"thundering\") legion; trajan raised it to a city. lying in a very fertile country at the crossing point of important routes, including the persian \"royal road,\" and two imperial military highways from caesarea and along the euphrates bank, it grew in size and importance, and was the capital of armenia minor or secunda. justinian, who completed the walls commenced by anastasius, made it the capital of armenia tertia; it was then a very great place (procop., _de aed._, iii. 4). the town was burnt by chosroes on his retreat after his great defeat there in 577. taken by the saracens, retaken and destroyed by constantine copronymus, it was presently recovered to islam, and rebuilt under mansur (a.d. 756). it again changed hands more than once, being reckoned among the frontier towns of syria (istakhry, pp. 55, 62). at length the greeks recovered it in 934, and nicephorus ii., finding the district much wasted, encouraged the jacobites to settle in it, which they did in great numbers. a convent of the virgin, and the great church which bears his name, were erected by the bishop ignatius (isaac the runner). from this time malatia continued to be a great seat of the jacobites, and it was the birthplace of their famous maphrian barhebraeus (or abulfaragius). at the commencement of the 11th century the population was said to number 60,000 fighting men (assem., _bib. or._, ii. 149; cf. barheb., _chr. eccl._, i. 411, 423). at the time of the first crusade, the city, being hard pressed by the turks under ibn danishmend, was relieved by baldwin, after bohemund had failed and lost his liberty in the attempt. but the jacobites had no cause to love byzantium, and the greek governor gabriel was so cruel and faithless that the townsmen were soon glad to open their gates to ibn danishmend (1102), and the city subsequently became part of the realm of kilij arslan, sultan of iconium. see h. c. b. v. moltke, _briefe uber zustande, &c. in der turkei_ (1835-1839). (d. g. h.)",
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