A Survey of the Parasites of the Brown Norway . BY W. R. FIRLOTTE* THE IMPORTANCE of the , norvegicus, as a res- ervoir of disease has long been recognized. Although its greatest importance lies in its harbouring and directly or indirectly transmitting bacterial diseases such as Plague, Rat-bite Fever, Spirochaetal diseases, Equine Influenza and Foot-and-Mouth Disease, its ability to disseminate parasitic diseases is well known. It is for this reason that a thorough knowledge of the parasites of is desirable in any country. In the past, surveys of rat parasites have been conducted in almost every part of the world. However, to our knowledge, no complete list of the parasites of this host has been published in . Of these numerous surveys of rat parasites, some were primarily on particular spec- ies or phyla of parasites, while others were more complete. In Europe, Balfour (3) reported the parasites of 444 brown rats in while Newstead and Evans (17) in Liverpool, Strickland and Merriman (21) in Suffolk and North Essex, and Hirst (11) gave reports on the incidence of the ectoparasites of rats. Baldassari (2) reported the findings in 225 rats in Toulons (France) while Marcandier and Pirot (14), also in Tou- lons, reported on the ectoparasites of the host. In the United States, An- drews and White (1) reported the parasitic protozoa while Luttermoser (13) reported the parasitic helminths of 2,500 Baltimore house rats. Re- ports were also published by Price and Chitwood (18), Moll (16), Forbes (9), and Cram (8). In Canada, the majority of rat surveys were conducted primarily for the determination of the flea population and particularly the "c!voopis index" since this flea is the main carrier of plague. Such surve- ave been conducted by Spencer (19, 20) in Vancouver, Gibbons and Hurm reys (10) in Vancouver and New Westminster, and Brown (7) also in W -tern Canada. More recently Kuitunen-Ekbaum and Webster (12), in Toronto, examined 650 rats and reported upon the incidence of . Materials emd Methods A total of 150 rats were examined. These rats were either trapped or shot with a .22 calibre rifle at the Macdonald College quarry which is used as a dump, or, in its immediate vicinity. The 106 rats that were trapped alive were taken to the laboratory, chloroformed one by one in a small chamber, combed, weighed and dissected. Rats that were killed (44) through shoot- ing or trapping were, upon death, placed in a large paper bag securely tied as to prevent the escape of ectoparasites and then taken to the lab- oratory for examination. Of the 150 rats examined, 83 were males and 67 were females, six of which were pregnant with an average litter of 7. The weights of male rats varied from 110 to 450 grams; that of the females from 110 to 380 grams, excluding pregnant . *Institute of Parasitology, McGill University, Macdonald College, Que. [187] canadian Journal of Rat July, 1948 188]18]Comiparative Medicine Parasites of the Norway Vl I o Thin films were prepared with blood removed from the heart with a hypodermic needle and syringe. The films were stained with Leishman's stain. The internal organs were examined macroscopically for abnormal- ities and if such were observed, a careful examination was made to de- termine whether or not they were of parasitic origin. The urinary bladder was also removed and examined with the aid of a dissecting microscope for the presence of Trichosomoides crassicauda. All the surfaces of the hepatic lobes were examined for cysts of Cysticercus fasciolaris and for fibrotic encapsulations of Capilaria hepatica and its eggs which appear as white or yellow spots or patches. The cysts were opened and the in- cluded cysticerci removed. If spots were noticed, scrapings of the liver were taken and examined under the microscope for ova. The diaphragm was removed and examined in a compressorium for the presence of en- capsulated larvae of spiralis. A thin layer of muscle teased from the hind leg and the jaw was examined in the same manner for sarcosporidia. The alimentary tract was divided into five parts: stomach, duodenum, (the first 5 inches of the small intestine), small intestine, caecum and large intestine. Each section was individually opened and thoroughly examined. Smears in saline of the contents of the small intestine and caecum were made and examined for protozoa. Smears of the contents of the large intestine were also made, fixed in Schaudinn's solution and stained with Heidenhain's iron haematoxylin. After the contents of the large intestine had been examined for helminths, they were submitted to a zinc sulphate flotation and examined for cysts and ova. Results The total number of species of parasites found in this survey is 18, made up of 5 species of protozoa, 3 of cestodes, 6 of nematodes, 1 species of louse and 3 of mites. They are listed in Table 1 with the per- centage incidence. Although blood protozoa have been found in the blood of rats on Montreal island, a thorough search during this work did not reveal the presence of such parasites. Coccidia are not reported numerically but measurements of oocysts found in 25 rats showed that all three species reported by Becker, Hall and Hager (4, 5, 6) were present with Eimeria miyairii being most common, E. separata occupying an intermediate posi- t on and E. carinii being found only once. Cysticercus fasciolaris, the larval form of the cat tapeworm Taenia taeniaformis was found in 67 rats (45%) with an average of 1.55 cysts per rat. This appears to be a natural confirmation in Rattus norvegicus of an acquired immunity for Cysticerous fasciolazis as demonstrated by Miller (15) 'in laboratory rats. The longest cysticercus found was 4.5 inches long and the largest infection was 15 cysticerci. Hymenolepis murina was found in 25 rats (,16.5%) with a total number of 63 worms - in whole or in part - and with infections ranging from 1 to 10 worms. All of these worms were found in the small intestine and in one rat four scolicies only were found upon examination of the in- of CanadiJour4alCmmnparativ. Medcine Parasites of the Norway Rat VlV-l.II-N o [1891 testinal contents. This is in accordance with the fact that H. murina has a direct life cycle as demonstrated by Woodland (22) and others. TABLE 1 Protozoa percent Nematodes incidence Nippostrongylus muris...... 83.0 Heterakis spumosa ...... 79.3 Coccidia...... 28.0 Trichosomoides crassicauda...... 55.5 Trichomonas muris ...... 9. Strongyloides ratti ...... 8.0 Giardia muris ...... 6.0 Capillaria hepatica ...... 6.0 Chilomastix bettencourti ...... 1 Mastophorus murs...... 0.66 Entamoeba muris ...... 6.7 Lice Cestodes spnulosa. 7.3 Cysticercus fasciolari ...... 44.6 Mites Hymenolepis murina ...... 16.5 Echinolaelaps echidninus...... 1.3 Hymenolepis diminuta ...... 4.0 Laelaps spp ...... 4.0 Radfordia spp . 0.66 Hymenolepis diminuta was found in 6 rats (4.0%) with infections ranging from 2 to 17 worms. Of all the helminths, N;ppostrongylus muris appeared in the great- est number of infections involving 124 rats (83%). Infections ranged from 1 to 290 worms with a total of 3495 worms and an average of 28.2 worms per rat. Heterakis spumosa was found in 119 rats (79.3%) with infections ranging from 1 to 76 worms. In all, there were 1355 worms with an average of 11.4 worms per rat. The bladder worm Trichosomoides crassicauda was found in 83 rats (55.5%) with an average of 1.3 per rat. Of the 12 rats infected with Strongyloides ratti, the largest infection was 5 worms with an average of 1.9 worms per rat. Capillaria hepatica was diagnosed en- tirely by its characteristic eggs which were found in zinc sulphate 'flota- tion of the large intestine contents. Adult worms or hepatic lesions were not found. Mastophorus muris var. muris was found in one rat only ir_ the anterior part of the small intestine close to the stomach. Only one worm was found; the specimen was a female 36.0 mm. long. Of the ectoparasites, the common rat louse was the commonest form. Twenty lice were found on the 11 infested rats. Only two single infestations of Echinolaelaps e0chidninus were found whereas 6 rats harboured a mite ascribed to'the genus Laelaps with an average of 2.3 mites per infested rat. Only one mite ascribed to the genus Radfordia was found. This single mite could not be identified as to spec- ies because of damage to the body proper. In addition to the ectoparasites mentioned above, the flour beet! Tribolium confusum was found as an accidental inhabitant of the of the rat. No fleas were found during this survey. All the parasites here recorded have been reported in the past from similar surveys. The parasites having a cosmopolitan distribution are: Helminths. Cysticercus fasciolaris, Hymenolepis murina, H. diminuta, Trichosomoides crassicauda and Capillaria hepatica; Ectoparasites. Po- lyplax spinulosa and Echinolaelaps echidninus. The distribution of the protozoa cannot be determined as yet since- records are lacking for many parts of the world. Canadian Journal of Parasites Rat July, 1948 [190Q Comparativeof theMedicineNorway ~~~~~~~~Vol. XII -No. 7 In a similar survey of "dump" rats in Baltimore, Andrews and White (1) reported a coccidial infection of 3.9% and a Trichomonas infection of 20.0% as compared to 28.0% and 9.0%,/ respectively as shown in Table ,. In the same rats as those studied by Andrews and White, Luttermoser (13) found a lesser infection with Cysticercus fasciolaris (25.4%), Hy- menolepis murina (14.1%), Heterakis spumosa (1.7%) Nippostrongylus muris (61.5%) and a greater infection with H. dim nuta (9.9%), Trichoso- moides crassicauda (91.1%), Strongyloides ratti (64.7%) and Capillaria hepatica (82.3%). In addition, Luttermoser reported finding of Trichinella spiralis, Syphacia obvelata and Moniliformis moniliformis which were not found here. On the other hand, Mastophorus muris var. muris was found in the present survey while it was not found in the Baltimore survey. Over 40 percent of the rats harboured multiple infections of 4 hel- minths; 11 percent with 5 helminths; and 2 rats only with 6 helminths. These 2 rats harboured similar infections with 5 helminths: Cysticercus fascSiodaris, Hymenolepis murina, Trichosomoides crassicauda, Nippo- strongylus muris and Strongylol4des ratti; the sixth worm in each case being Capillaria hepatica and Mastophorus muris var. muris. Four percent had multiple infections of 3 protozoa: coccidia, Giardia muris and Tri- chomonas muris or Entamoeba muris, and 6 percent had double infections. Only 2 rats were found to harbour the and a species of mite in double infestations. Summary ond Conclusions 1. On examination of 150 rats, Rattus norvegicus, from the region of the quarry at Macdonald College, 5 protozoa, 3 cestodes, 6 nematodes, 1 louse and 3 mites were found all of which had been previously reported. The incidence (in percent) was as follows: Protozoa. coccidia. 28.0; Trichomonas muris, 9.0; Giardia muris, 6.0; Chilomastix bettencourti, 2.1; and Entamoeba muris, 6.7: Cestodes. Cysticercus fasciolaris, 44.6; Hyme- nolepis murina, 16.5; and H. diminuta, 4.0: Nematodes. Nippostrongylus muris, 83.0; Heterakis spumosa, 79.3; Trichosomoides crassicauda, 55.5; Strongyloides ratti. 8.0; Capillaria hepatica. 6.0; and Mastophorus muris var. muris, 0.66: Lice. Polyplax spinulosa, 7.3: Mites. Echinolaelaps echid- ninus,,1.3; Laelaps spp., 4.0; and Radfordia spp., 0.66. 2. Trematodes, fleas, haematozoa, and the nematode Trichinella spiralis were not encountered at all throughout the survey. 3. Of the 150 rats examined, all of which were adults, 83 were males ranging in weight from 110 to 450 grams, 67 were females weighing from 110 to 380 grams excluding the 6 pregnant animals the heaviest of which weighed 385 grams with a litter of 9. 4. The parasites found which may' be transmitted to man are Hyme- nolepis diminuta, Capillaria hepatica, and perhaps Hymenolepis murina. Bibliography (1) ANDREWS, JUSTIN, AND WHITE, HARRY F. An epidemiological study of protozoa parasites in wild rats in Baltimore, with special reference to Endamoeba histolytica. Amer. Jour. Hyg., 24:184-206. 1936. (2) BAWASSARI, M. T. Le parasitisme des rats a Toulons. MarseMie Med., 16:717-718. 1935. (3) BALFOUR, A. Observatioms on wild rats in and an account of their eto-and endo- parasites. Parasit., 14:282-288. 1922. Canadian Journal of of the Rat v.iX , 198o7 Cemparative Medicine Parasites Norway VoL xUI-No. 7

(4) BECKER, E. R., HALL, PHOEBE, R., AND HAGER, ANNA. Quantitatire, biometrical and host- parasite studies on Eimeria miyairii and Eimeria separata in rats. Iowa State College Jour Sc. 6:299-316. 1932. (5) BECKER, E. R., AND HALL, PHOEBE, R. Eimeria separata, a new species of coccidiutm from the Norway rat (Epemys norvegicus). Iowa State College Jour. Sc., 6:131. 1931. (6) BECKER, E. R., AND BURROUGHS, R. D. Rediscovery of Eimeria carinii Pinto, 1923. Jour. Parasit., 20:123. 1933. (7) BROWN, JOHN H. The fleas (Siphonaptera)- of , uwith a list of the known vectors of sylvatic plague. Ann. Ent. Soc. Amer., 37:207-213. 1944. (8) CRAM, E. B. A note on parasites of rats. Jour. Parasit., 15:72. 1928. (9) FORBES, W. C. Helminths from the Norway rat in Northeasten Ohio. Jour. Parasit., 28:431. 1942. (10) GIBBONS, R. J., AND HUMPHREYS, F. A. Plague surveys in Westen Canada. Can. Pub. Health Jour., January, 1941. (11) HmST, S. Preliminary list of the acari occurring on the brown rat (Mus norvegicus) in , with the description of a new species (Haemogamasus oudemanus). Bull. Ent. Res., 5:119-124. 1914-1915. (12) KUITUNEN-EKBAUM, E., AND WEBSTER, DOROTHY. Trichinosis in wild rate in Toronto. Can. Jour. Pub. Health No. 2, 38:76-78. (31) LUTTERMOSER, G. W. A helminthological survey of Baltimore house rats (Rattus norvegicus). Amer. Jour. IHyg., 24: 350-360. 1936. (14) MARCANDIER, M., AND PIROT, R. Etude sur les ectoparasites des rats de Toulons. Bull. Soc. Path. Exot., 25:237-244, Paris. 1932. (15) MILLER, H. M. Jr. Immunity of the white rat to super-infection with Cysticercus fasciolaris. Proc. Soc. Exp. Bio. and Med., 28:467468. 1931. (16) MoLL, A. M. Aninml parasites ofrats at Madison, Wisconsin. Jour. Parasit., 4:89-90. 1917. (17) NEWSTEAD, R., AND EVANS, A. M. Report on rat-flea investigation. Amer. Trop. Med. and Parasit.. 15:287. 1921. (18) PRICE, E., AND CHITWOOD, B. G. Incidence of intestinal parasites in wild rats in Washington, D. C. Jour. Parasit., 18:55. 1931. (19) SPENCER, G. J. The menace of rat parasites in Vancouver in 1936. Proc. Ent. Soc. B.C., No. 33:44. 1937. (20) SPENCER, G. J. Further notes on the fleas of British Columbia. Proc. Ent. Soc. B. C. No. 34: 36-38. 1938. (21) STRICKLAND, C., AND MERRIMAN, G. 1. Report on rat-fleas in Suffolk and North Essex. Parasit., 6:2-18. 1913. (22) WOODLAND, N. F. On the life of H. fraterna (H. nana var. fraterna Stiles) of the white mouse. Parasit., 16:69-83. 1924.