Parasites of Eskimos at Igloolik and Hall Beach, Northwest Territories
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ft I 306 Zoonotic and infectious diseases Parasites of Eskimos at Igloolik and Hall Beach, Northwest Territories R.S. FREEMAN andJ. JAMIESON There are relatively few reports that discuss the incidence of human intestinal parasites in the people of the near Arctic. There have been a few surveys along the coast of Alaska, others from Canada, mainly below the Arctic Circle (3,4,10) and at least one survey from the west coast of Greenland (2). All describe relatively high, albeit variable, incidences of intestinal parasites, including protozoans and usually some metazoan eggs. As Babbott et al. stated for Greenland (2), the level of parasitism" .•• was comparable to many tropical regions." There are a few studies on the biology of metazoan parasites of natives, mostly from Alaska (11, 12). The present report adds to scanty knowledge of the incidence of human intestinal parasites in the far north of eastern Canada (4,5,9) particularly Igloolik and Hall Beach, NWT (3). Particular objectives of the study were to estab lish the identity and shed light on the biology of Diphyl lobothxium sp. (3), and to determine whether D. latum occurs in the eastern Canadian Arctic (1,5,9,ll,16). MATERIALS AND METHODS The senior author collected faecal specimens on two short trips in May-June 1970 and August 1971. Local workers also collected faecal specimens at Hall Beach and Igloolik in September-October 1970; these were treated with formalin and sent to Toronto for examination. A total of 352 faecal samples, from more than 300 Eskimos out of a total native population of just over 700, were examined. In May-June 1970, 171 pinworrn swabs were also collected. A modified Ritchie-Formalin-Ether centrifugation con centration technique (RFE) (13) was used on all specimens. Some specimens were also stained with Scholton's modified iron haernatoxylin (SIH) procedure (15). One of us (J.J.) spent May-September 1971 collecting helminth parasites from Arctic char and a few other spe cies of fist from nine areas of the upper Foxe Basin, as well as observing the biology of Eskimos in summer camp. Two types of tapeworm plerocercoids were removed from Parasites of Eskimos 307 Arctic char (Salvelinus alpinus (L.)) and a second worm tentatively identified as Diphyllobothrium sp.; these were fed to five Caucasian volunteers and two dogs. Two humans and one dog became infected with one type. Four adult worms were purged from the human volunteers using magnesium sulphate, atabrine, sodium bicarbonate, and phenobarbital as recollllllended by Rausch et al. (12). The worms were fixed in hot or cold 10 per cent formalin, stained, and either shaved, sectioned, or mounted in toto for study. RESULTS Results are summarized in Table 1. Because of the low inci dence of pinworms in May-June 1970, this aspect of the study was not continued in the autumn of 1970 or in 1971. The data for May-June 1970 and August 1971 are comparatively consis tent, and are based on field study of RFE concentrates and additional SIH specimens prepared on return to the labora tory in 1971. The apparent discrepancies between these sam ples and those collected in September-October 1970 may re sult from both smaller sample sizes and from the use of for malin-treated samples. The latter provide less consistent information than results obtained with unfixed faecal sam ples. The higher incidence of parasites found in August 1971 undoubtedly reflects both a true increase in the inci dence of helminth ova, and the fact that several protozoa! infections, overlooked in RFE procedures, were detected with the SIH technique. Two types of plerocercoids of Diphyllobothrium spp., the stage infective to the homiothermic vertebrate host, were conunonly found on and within various viscera from Arctic char. One type was large, characteristically wrinkled, or even segmented (Figure 1), and was subsequently identified as Diphyllobothrium dendriticum (Nitsch); this type was less ubiquitous and less cormnon in absolute numbers than the second type. The latter was small, characteristically "smooth" (Figure 2) and found in all areas where Arctic char were collected, being at least four times more conunon than D. dendriticum. The results of limited feedings of both types of plerocercoids to Caucasian volunteers and dogs (Table 2) were monitored with the RFE technique, be ginning seven days after ingestion of plerocercoids and continuing weekly for seven weeks if eggs were not found. Four DiphyllobothriuD dendriticum were purged from the t'..:o ir,fected huraans ( 8) , but one dog, although passing eggs TABLE 1 Intestinal parasites of Eskimos in Hall Beach and Igloolik, NWT 1970 1970 1949* 1971 May-June Sept.-Oct. August August Igloolik Igloolik Hall Beach Igloolik Hall Beach Igloolik Pinwonn swabs (examine4"' infected) 60/33 77/5 94/2 Faecal samples (examined/% infected) 97/47 78/47** 73/48** 46/33** 32/59** 123/53** Entamoeba coli (% infected) 8 30 38 17 38 29 Entamoeba histolytica (% infected) 0 0 0 0 3 0 Endolimax nana ( % infected) 4 12 6 9 22 24 Giardia lamblia (% infected) 2 17 29 9 28 11 Other flagellates (% infected) 0 0 0 0 0 2 Diphyllobothrium sp. (% infected) 33 0 0 9 0 2 Diphyllobothrioid eggs (% infected) 0 0 0 0 0 6 Fluke (?) eggs (% infected) 0 0 0 0 0 2 Enterobius vermicularis (% infected) ? 0 0 0 0 2 Unidentified eggs (?) (% infected) 0 0 0 0 0 2 * From M. Brown, et al., Can. J. Public Health 41: 508-12 (1950). ** Some multiple infections. TABLE 2 Results of feeding plerocercoids of Diphyllobothrium spp. to humans and dogs Number of Days until plerocercoids Days until purge (p) or Worms fed eggs seen autopsy (a) obtained Diphyllobothrium dendriticum Caucasian No. 1 3 11 72? (p) 3* (second feeding) 6 ? 14? (p) Caucasian No. 1 8 None seen not done 0 Caucasian No. 2 6 10 32 (p) l Dog No. 1 6 None seen 24 (a) 0 Dog No. 2 6 7 24 (a) 0 Diphyllobothrium sp. (smooth) Caucasian No. 3 6 None seen Not done 0 Caucasian No. 4 2 None seen Not done 0 Caucasian No. 5 3 None seen Not done 0 * Nnt- \cl"'lnwn if nr1.\11t- worms 14 nr 72 rletv~ old_ Parasites in Eskimos 309 Figure 1 Plerocercoid of Diphyllobothrium dendriticum, anterior half on the left; notice distinct segmentation (scale = 5 mm) Figure 2 Plerocercoid of Diphyllobothrium sp.; notice much smaller size, smooth outline of body, and lack of segmenta tion (scale = 1 mm) 310 Zoonotic and infectious diseases within seven days, showed no parasites when autopsied 17 days later. The smaller plerocercoids did not establish themselves in man (Table 2). DISCUSSION Changes in the incidence of parasites in 1970-71 compared with 1949 (3) are presumably conservative estimates, since in most instances the more recent data are based on single samples. Pinworms (E. vermicularis) are down markedly, as are head lice according to the nurses, although we did not examine for them. Interestingly, the over-all incidence of intestinal parasitism has not changed -nearly half the Es kimos still harbour one or more types of parasites - but the relative incidence of various species of parasites has changed. Protozoans have increased at least fourfold, while worm infections have declined to a slightly smaller extent. Giardia lamblia, a mild pathogen, is much more abundant than formerly. The single infection with Entamoeba histoly tica probably was acquired when this individual was re ceiving treatment for another condition in southern Canada. Conceivably, Dientamoeba fragilis were overlooked in the SIH preparations made in 1971. The identity of the cestodes is intriguing. Towards the end of the last collecting trip, an iodine-stained slide dried by accident, and it was then discovered that at least two types of eggs were present in the stools. One, with a typical smooth shell, can be associated with Diphyllobo thrium spp. of fresh-water origin (7). The other, with a deeply pitted scrobiculate shell, is typically associated with various diphyllobothrioid cestodes of marine origin (7). Whether the latter were present in 1949 is unknown. A single attempt to purge a patient passing scrobiculate eggs was unsuccessful. Successfully infecting man and dog with plerocercoids from Arctic char (Table 2) and producing non scrobiculate eggs (N = 350, range 48-72~x = 63.3A)(8) suggests that the smooth-shelled eggs of the same size range obtained from the Eskimos are Diphyllobothrium den driticum. This is almost certainly a zoonosis, maintained elsewhere in the world by gulls. The species becomes pa tent in less than two weeks in man and is relatively small and short-lived; in contrast, D. latum requires four weeks or more to become patent, may live for several years, and is quite large (8, 11}. Since no eggs were found in the stools in the spring, this further supports the assumption that the smooth-shelled eggs found later in the summer are Parasites in Eskimos 311 Figure 3 Photograph of eviscerated Arctic char with plero cercoids, indicated by pencil, encysted on lateral peri toneum. the short-lived D. dendriticum. This species is probably of little consequence to health. The Eskimos continue to eat uncooked, unfrozen Arctic char, although probably less than was fonnerly the case. They eat only the flesh and occasionally a ripe roe. From conversation and observation it is apparent that the Eski mos are unaware of the presence of the plerocercoids. How are plerocercoids of Diphyllobothrium sp. ingested, since they are relatively rare in the roe (<4 per cent) and do not occur in the flesh, being mainly on and in other vis cera (~25 per cent) or attached to the lateral peritoneum (~10 per cent) (8)? Quite likely, a few plerocercoids from roe are ingested, but probably most come from those attached to the lateral peritoneum (Figure 3) • Often the fish are filleted and the flesh separated from the skeleton.