in3;<). While some of those records niiiv he due to eoiit'usion 

 of elosoly rehited species, there is no reason to donlit th;it in 

 some ciises the worms actually were 1). mcdininsis. There is no 

 evidence, however, that any of these animals are si{;riilicant 

 reservoir hosts in the endemic areas. Infection in aniumls, liow 

 ever, might serve to spread this jiarasite into new areas as 

 suggested by its presence in animals in Chimi (Ilsii and Watt, 

 VXV.>.) and in the United States (Chitwood, 1!)33) where en- 

 demic cases in man have never been reported. 

 INJURY TO HOST 



There appears to be no evidence that the guinea worm appro 

 ciably injures its host during tlu- developmental period in the 

 deep connective tissues. Just before the female worms reach 

 the skin they secrete toxins which produce general symptoms 

 such as urticaria, nausea, vomiting, diarrhoea, severe dys]Hiea, 

 and syncope. These symptoms disapjjoar after the worms have 

 established an opening through the skin. Later injury to the 

 host is produced by secondary infection and by tissue reactions 

 to the worms liefore and after their deatli. Severe inflammation 

 is produced if the worms are broken in the tissues and the 

 embryos freed. The iiresence of the guinea worms may also 

 produce permanent joint injuries (Pradhan, liiHO). 



Tn endemic areas dracontiasis is often a medical and public 

 health jiroblem of great importance. Large numbers of people 

 are iru'apacitated for 3 to <i months of the year; severe sulier- 

 ing and occasionally death are produced; and the economic life 

 of the community is often severely disturbed. For example, 

 Moorthy (1932a) stated that iu certain villages in the endemic 

 areas of Mysore a large jjercentage of tlie people were more 

 or less completely incapacitated for ."i to li months of the year 

 and that outside labor had to be imported. The statements of 

 other authors indicate that this samp situation holds in the 

 enormous number of villages in various parts of India where 

 this parasite is endemic. Also over large areas of Tropical 

 Africa the guinea worm is a real scourge. 



GEOGRAPHICAL DISTRIBUTION* 



Dracontiasis is widely distributed in a number of parts of 

 Tropical Africa and is endemic over large areas of India. It 

 is also found in Arabia, Iran, Afganistan, and Russian Tur- 

 kestan. It is supposed to have been introduced into the West- 

 ern Honiisphere with slaves from the Gulf of Guinea. It was 

 formerly thought to have become endemic in Curacao, Demerara, 

 and Surinam but seems now to have disajipeared; it is only in 

 a limited region in the state of Bahia, Brazil, that it is still 

 endemic. There is other evidence that the guinea worm is not 

 easily spread to new regions. Although it has been constantly 

 introduced into the Dutch East Indies it apparently has never 

 been establislied (Brug, 1930) and no evidence was found of 

 endemic centers along the north coast of Africa and in southern 

 Europe. 



In Africa are located the most widespread and perhaps the 

 worst endemic areas of guinea worm infection in the world. 

 In general it can be said that almost all the important endemic 

 centers in Africa are north of the equator and south of the 

 Tropic of Cancer. In West Africa they are in general scat 

 tered from Mauritania to Gabun, especially in Mauritania. 

 Senegal, Upper Volta, Ivory Coast, Gold Coast and Northern 

 Territories, Togo, Dahomey, Nigeiia, and Cameroon. East of 

 this region endemic areas are known especially East of Lake 

 Chad, over much of the southern part of the Anglo-Egyptian 

 Sudan and in Uganda. 



In Arabia the guinea worm is present along the shore of 

 the Bed Sea and in some places in the interior; it is endemic 

 in certain jiarts of Russian Turkestan, Afganistan, and in Iran 

 it appears to be almost entirel.v limited to certain towns and 

 villages in the province of Laristan, wiiicli is located in the 

 .south on the Persian Gulf (Lindberg, 1930). 



Next to Africa the real home of the guinea-worm is India. 

 Imjiortant endemic centers in this country are limited to the 

 western half of the peninsula, little infection being found east 

 of Delhi and the Central Provinces. In Rajputana and Central 

 India the infection exists almost everywhere except in a few 

 desert regions; in the Central Provinces it is prevalent in all 

 the districts except a few on the eastern side; in the Bombay 

 Presidency it is widely distributed except in the sea coast 

 area south of Bombay; in the iladras Presidency it is preva 

 lent except for a few districts on the western coast; in Hydera- 

 bad 9 out of 16 districts liave the infection; in Mysore it is 

 practically limited to one district in the north ; it is also pres- 

 ent but with lower incidence in the valle.v of the Indus and 

 the Northwest Frontier Provinces; elsewhere in western and 

 central India there are a few limited centers. 



*Infortnation gathered by questionn.iires and suniiiied up in a recent 

 work by E, B. lIcKinley (]9;^5) suppleniented the numerous luiblica- 

 tions found in the lite ature on the distril)Ution of dracontiasis in vari- 

 ous parts of the wfirld. A personal communication from Dr. V. N. 

 Moortb\' gave ^the latest information on India. 



'I'hcn' are certain general iioints of iiitori'st in regard to the 

 geogra|ihical distribution of dracontitisis. It extends from the 

 tropics in -Xfrica and southern liuiia well up into the tem- 

 perate zone in Russian Turkestan, Afgaiii.stan. .and the innth- 

 western frontier i)roviiK'es of India. Even where it is wide- 

 spread .as in tropical .\frica north of the e(iuator and in west- 

 ern and ccntr;il India, its distribution is very discontinnous, and 

 importtmt endemic centers are often separated by wide areas 

 where it is not present. In limited regions too its distribution 

 is very si)otted. In Mysore, for examide, the infection is al- 

 most entirely limited to the Chitaldrug district, and in this 

 district itself there w-as only a small iiroiiortion of infected 

 villages which are widely scattered (Moorthy, 193:ia). The 

 same spotted distribution has been noted by other authors in 

 the other endemic areas of India. The same type of distribution 

 has been noted by vari(uis workers in different parts of Africa, 

 where guinea worm villages may be close to others where the 

 parasite is absent. It has also been noted that in an infected 

 village itself only part of the families suffer. Even more sur- 

 prising is the point emphasized by Moorthy (1932a) and Trewn 

 (1937) that in infected families, where there appear to be no 

 differences in habits, some Individuals will remain entirely free 

 from infection. All these peculiarities of distribution suggest 

 that the factors involved in the dissemination of the guinea 

 worm are very complicated. 



EPIDEMIOLOGY 



In general it may be said that the guinea worm can only 

 spread where infected individuals wade or bathe in drinking 

 water in which Cyclops are present. While most of the endemic 

 areas are in hot countries there is no evidence that tempera- 

 ture per se is a determining factor. This parasite is chiefly 

 prevalent in regions where there is a low annual rainfall. This 

 seems to be related to the fact that in such regions the people, 

 during at least part of the year, are forced to depend for their 

 drinking water on open pools, wells, or cisterns in which the 

 population of Cyclops becomes concentrated. In a personal 

 communication Dr. V. N. Moorthy recently made the follow- 

 ing statement in regard to the distribution of dracontiasis in 

 India: "The most significant fact to note in this distribution 

 is that the intensity of infection appears to vary directly with 

 the scarcity of water supply during the season of infection. 

 In provinces like Bengal and Assam where there is a plentiful 

 supply of water all through the year dracontiasis hardly exists 

 at all." Roubaud (1913) and others have also pointed out 

 that in the forested regions of west equatorial Africa where 

 the rainfall is abundant, as the lower Ivory Coast and the 

 Congo Basin, guinea worm has not been observed. 



A number of authors have noted a seasonal relation in guinea 

 worm infection. Since the development of the worms takes 

 about a year, the yearly period when the people are suffering 

 from the disease coincides with the conditions most favorable 

 for its transmission. In India the outbreaks are almost en- 

 tirely limited to the first half of the year with most of the 

 infection coming in March, April, and May. This is the driest 

 season just before the Monsoon. In Dahomey, Roubaud (1913) 

 found the disease most frequent also in the driest months of 

 the year which are from December to February. The same 

 author noted, however, that in the endemic areas of the Lake 

 Chad region it occurs almost entirely in the rainy season, 

 which is in the middle of winter. He explains this by the use 

 during this period of water from little cisterns and pools 

 which are temporarily filled. Davis (1931) lujted that epi- 

 demics of dracontiasis occurred in southern Sudan during the 

 rains from April to June. In Iran, Lindberg (193(3) found 

 the season of infection to be from March to August with the 

 maximum in June, which are the hottest months of the year 

 just after the rainy season. It is evident, therefore, that the 

 seasonal incidence of dracontiasis varies greatly in different 

 endemic areas and is related to the water supply of the people 

 and not to general climatic conditions. 



Little significant information is available on the relation of 

 the distribution of the various species of cyclops to the epi- 

 demiology of dracontiasis. These copepods are widely dis- 

 tributed over the world and immerous species occur wherever 

 they are found. In general, therefore, it seems possible that in 

 most regions ivhere the guinea worm would be introduced and 

 where the human habits are favorable for its spread, suitable 

 intermediate hosts would be present. Only certain species of 

 cyclops can serve as intermediate hosts. Chatton (1918) tried 

 to infect four different species of Cyclops in Tunis with larvae 

 from introduced cases. One of these, Cyclops macrnrus, was en- 

 tirely refactory to infection. In three others, C. viridis, C. 

 prasiniis, and an undetermined species, the larvae were ingested 

 and penetrated into the body cavity but failed to develop al- 

 though they remained alive for from 40 to .10 days. In India, 

 Lindberg (193:"i) fouiul that C. multicolor dies quickly after 



321 



