Clinical Changes Caused by the Liver Fluke Metorchis conjunctus in

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Clinical Changes Caused by the Liver Fluke Metorchis conjunctus in

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Clinical Changes Caused by the Liver Fluke Metorchis conjunctus in Cats

T. G. Watson and N. A. Croll

Vet Pathol 1981 18: 778

DOI: 10.1177/030098588101800608

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Vet. Pathol. 18: 778-785 (1981)

Clinical Changes Caused by the Liver Fluke Metorchis conjunctus in

Cats

T. G. WATSON and N. A. CROLL

Institute of Parasitology, Macdonald College of McGill University, Ste. Anne de Bellevue,

Quebec, Canada

Abstract. Cats infected with metacercariae of the fluke Metorchis conjunctus were followed

clinically through their infection. Cats given 200 metacercariae showed few symptoms. All the

cats passed ova on the 17th day. Three hundred metacercariae caused diarrhea, icterus,

discolored urine, green feces and eosinophilia after 18 to 21 days. Eosinophilia, Ieucine

aminopeptidase and alanine aminotransferase were elevated and remain the best indicators

for metorchiasis. The hematological and serological abnormalities resolved rapidly and were

absent from cats with chronic infection.

Acute lesions (


Metorchis in Cats 119

Materials and Methods

Male and female mixed-breed cats weighing 1.0 to 3.5 kg were treated with piperazine to

expel Toxocara cati and then housed in cages with a mesh bottom and a plate to rest on.

Water was provided ad libitum and each cat had about 100 g of Purina cat chow (Centre

Agricole St. Clet, St. Clet, County Soulanges, P.Q.) daily; feces were examined for ova with

the formalin-ether technique [ 171.

Viable metacercariae were digested from the muscles of the common sucker (Catastomus

commersoni) in artificial gastric medium. They were placed on the back of the cat’s tongue

and were swallowed or flushed down the throat; cats were observed carefully to rule out

vomiting of the inoculum.

Blood collection was done between 0800 and 1000 hours. Cats were sedated with ketamine

hydrochloride (0.05 mg/kg body weight); 4 ml of whole blood was removed by cardiac

puncture with an 18 gauge needle and 5 ml syringe. Heparinked, microhematocrit capillary

tubes were filled with whole blood for leukocyte and eosinophil counts in Unopette diluting

chambers (Becton-Dickinson, Rutherford, N.J.). The hematocrit packed cell volume was

measured from the remaining capillary. The remaining blood was clotted at 22°C for 30 to 40

minutes. The serum was frozen at - 17°C in 2- or 4-dram vials. The following tests were done:

total serum protein, albumin, and globulin (Sigma, St. Louis, Mo.), with a Coleman Junior I1

Model 6/20 spectrophotometer (Canadian Coleman Co. Ltd., Toronto, Ont.); serum protein

electrophoresis was done with a Corning 740 densitometer; serum bilirubin, leucine amino-

peptidase and alanine aminotransferase activity were determined by Boehringer Ingelheim

Mannheim GmbH Diagnostica (Waterford, Conn.); alkaline phosphatase was quantified by

Sigma (St. Louis, Mo.) technical procedures.

Three experimental infections were given as follows: Experiment I: Five cats, coded 1 to 5,

were given 200 metacercariae apiece while two controls were given placebo. Blood samples

were taken two days prior to infection, immediately prior to infection and on days 2, 4, 6, 8,

12,20 and 32 post-infection, when the cats were killed. Experiment 2: Cats 6 and 7 each were

given 300 metacercariae. Blood was sampled before infection and at weekly intervals after

infection until they were killed at day 59 (cat 6) and day 78 (cat 7). Experiment 3: Cats 8 to 12,

three female and two male littermates weighing 1.5 to 3.0 kg, were used. Two cats received 200

metacercariae, two received 300 and one was given placebo. Blood was collected before

infection and on days 7, 14, 17, 21, 24, and 28 and then weekly until day 77. On day 42 the

two cats given 200 metacercariae were given 300 more metacercariae apiece; their blood was

collected until day 9 1.

Each cat was anesthetized by ketamine, a final blood sample was taken and the cat was

killed with an intracardiac overdose of Somnotol (M.T.C. Pharmaceuticals, Hamilton, Ont.).

After midline incision, the ductus choledochus was ligated at the duodenum and the duodenum

was ligated above and below the ampulla of Vater. The gall bladder, cystic duct, common bile

duct and ductus choledochus were separated, as were the lobes of the liver. Each lobe was

sliced into 2- to 3-mm wedges and all tissues were examined for flukes. Representative tissues

were fixed in 10% formaldehyde. The spleen, pancreas and viscera were examined for worms,

lesions or enlarged nodes.

Results

The cats did not show identical or in some cases even similar clinical courses. Each

experiment will be discussed briefly, typical case histories presented and finally the

collected data will be given.

Experiment 1. Clinical signs-rectal temperature, food intake, stool quality, color,

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780 Watson and Croll

or consistency, urine output, vomiting, and behavior-were not different between

the controls and the infected cats. All infected cats passed ova from the 17th day

post-infection, and M. conjunctus was found in the biliary trees. Significant changes

(p = 0.05) in the measured parameters were examined by analysis of variance on log

transformed raw data. Differences were sought among the controls or among the

experimental cats during the infection and, finally, between the controls and experi-

mental cats on each day of sampling. Experimental cats showed: a significant

eosinophilia from days 12 to 32; a significant increase in albumin/globulin ratio; a

significant elevation in (YZ globulin, alanine aminotransferase and leucine aminopep-

tidase.

Experiment 2. Cat 6 was asymptomatic until fluke patency on day 17 when it

passed brown, watery feces without mucus, with ova. The diarrhea lasted for about

36 hours and returned irregularly until day 5 1; then it became continuous until day

59, when the cat was killed. Necropsy showed 252 adults of M. conjunctus (84%

establishment) with 80 in each lateral lobe and 24, 24, and 23 respectively in the

median lobes. No worms were found in the gall bladder or cystic duct, but 21 were

together in the common duct and extra-hepatic lobar ducts. No flukes were in the

caudal lobe.

Cat 7 followed a more spectacular clinical course and is considered a typical case

of symptomatic metorchiasis (table I). The cat was without symptoms until day 14,

when it developed scleral and dermal icterus, and the serum changed from pale straw

color to a canary yellow color. On day 14 the cat was emaciated, wet in the perianal

region, and had a rectal temperature of 38.5"C. It refused food and water, was anuric

and constipated on day 15, and had a temperature of 38.9"C. On day 16, reddish-

brown urine was expelled manually from the bladder. The cat lay in its cage, moved

only when induced, had stiff legs, and was apparently in considerable discomfort.

On day 17, 38.6 g of dense, gray feces with ova were expelled with a little yellow

mucus. The temperature was 38.9"C and a little reddish-brown urine was on the

floor of the cage; the cat ate and drank. By day 21 the cat could move slowly, ate

more vigorously, and expelled firm green feces. By day 22 the feces seemed more

normal and by day 28 the feces were normal and the serum was again straw colored.

The cat was killed on day 120.

All hepatic lobes of cat 7 were infected with M. conjunctus. There were 112 worms

in the main intrahepatic ducts of the left lateral lobe, 19 in the right lateral, 1 in the

median, 48 in the right median and 3 in the caudal lobe. One worm was in the cystic

duct, with a total of 183 adults (63% establishment).

Clinical laboratory values for cat 7 are given in table I. There was significant

eosinophilia in both cats between days 18 and 21. Leucine aminopeptidase and

alanine aminotransferase were elevated significantly in cats 6 and 7 between days 7

and 2 1 post-infection. No significant change occurred in alkaline phosphatase. Total

serum protein was stable in cat 6, but it was greatly elevated on days 18 to 21 in cat

7, which had concurrent severe clinical signs. On day 18 this elevation resulted from

increased globulin despite depressed albumin and a globulin.

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Table I. Hematological and serological findings for cat 7, inoculated with 300 metacercariae

Globulin Bilirubin

Eosinophils Prot Alb Glob Alb LAP SAP AAT

#/nun3% g/dl g/dl g/dl A/G % a p y w' ml SU/1 1U/I Tot Dir Indir

% % % mg/dl mg/dl mg/dl 5

- 2

387 2.1 6.6 3.30 3.30 1.00 50.2 29.6 11.1 18.5 5.50 0.42 39.8 0.194 -

2-

480 2.1 6.1 3.00 3.10 0.97 48.4 20.0 11.3 20.4 5.00 1.00 707.1 0.270 0.115 0.155 F'

5'

1920 7.9 7.8 3.68 4.12 0.89 47.2 23.9 12.1 16.9 8.83 2.02 348.7 7.852 5.774 2.078

5858 29.0 8.9 3.90 5.00 0.78 42.5 24.9 14.1 18.2 8.30 0.98 317.3 3.080 1.840 1.240 E i:

4746 19.1 7.7 3.50 4.20 0.83 45.6 23.5 12.7 18.0 7.16 2.30 364.6 1.210 0.650 0.560

1616 6.7 6.9 3.15 3.75 0.84 45.5 23.2 12.1 18.9 6.66 1.38 151.8 0.454 0.144 0.310

WBC

x 103

/m3

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18.5

22.3

24.4

20.2

22.6

24.1

vet.sagepub.com

post-infection; WBC = white blood cells; alb = albumin; glob = globulin; A/G = albumin: globulin ratio;

= leucine aminopeptidase; SAP = serum alkaline phosphatase; AAT = alanine amhotransferase.

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782

,OOt

I

b I

Watson and Croll

300

7 14 21 28 35 42 49 56 63 70 77 84 91

DAYS POST INOCULATION

Fig. 1: Absolute numbers of eosinophils in circulation of two cats given 200 metacercariae

of Metorchis conjunctus, per 0s on day 0 and 300 more on day 42.

Experiment 3. All infected cats started passing ova on day 17. A total of 340 adults

of M. conjunctus were in the left lateral lobes of the four infected cats, and 224 in the

right lateral lobes. Only 129 were recovered from the left median lobes and 77 from

the right; there were no flukes in the caudal lobes of any cats. The rate of

establishment varied between 40.4% and 59.7%; cat 9, which received a second

inoculum on day 24, had 202 worms (40.4% of its total inocula), and cat 10, also re-

inoculated, had 294 worms (58.5% of its total doses). Cats 11 and 12 had 179 (59.7%)

and 142 (47.3%) respectively.

Eosinophilia occurred between days 14 and 28 post-infection in all cats. Reinfection

caused renewed absolute and relative eosinophilia between days 7 and 21 after

reinfection. No clear protection from reinfection was conferred by a primary infection

six weeks earlier, although the second eosinophil peak was lower (fig. 1).

Lesions from single inoculum infections, less than 100 days old and with fewer

than 100 worms, were confined largely to the major branches of the lobar bile ducts.

The ducts were palpable from the surface of the liver and were faintly discolored,

but had no superficial nodularity or irregularity. The intrahepatic ducts were dilated

and the walls were thickened with dense fibrosis to a maximum thickness of 4 mm.

Typically, there was no extrahepatic duct involvement, but dark green or yellow

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Meforchis in Cats 783

viscous exudate with cell debris and ova occupied these ducts. The gall bladders

often were distended but the walls were not thickened. Many cats had enlarged

mesentenc lymph nodes [9], and one cat had four. The severity of gross lesions was

directly related to the intensity of the worm burden. Cat 7 had 112 worms in the left

lateral lobe, which contained bile and cell debris; extensive primary and secondary

bile duct enlargement; and conspicuous fibrosis.

Short-term patent infections of under 32 days were characterized by extensive

epithelial exfoliation. Pressure atrophy of the ducts was seen when the worms

completely filled the distended ducts. Fibrosis was restricted to the portal regions in

the borders between the bile ducts and the hepatic parenchyma. Cellular infiltrates,

rich in eosinophils but without increased lymphocytes or plasma cells, were in the

lamina propria of the dilated and hyperplastic ducts. Extrahepatic damage was

generally slight and was restricted to epithelial hyperplasia.

Cats killed between 32 and 150 days post-infection also had extensive exfoliation

of the biliary duct epithelial cells. There was widespread hyperplasia of the biliary

epithelium and large areas of adenomatous tissue. Intense eosinophilic infiltrates

were replaced by mononuclear cells in the more chronic infections.

Cats 8 and 9, reinfected 42 days after primary infection, showed both chronic and

acute lesions when killed on day I13 post-infection. Chronic lesions generally were

characterized by extensive proliferation of connective tissue, which replaced adeno-

matous hyperplasia. Another cat, given 300 metacercariae and killed on day 719

post-infection, had granuloma formation around the ova. Ova often were surrounded

by inflammatory cells, obstructing the intrahepatic bile ducts.

Discussion

Almost all cats with M. conjunctus had only brief diarrhea and anorexia. Classical

features of acute hepatic distress such as icterus, listlessness, abdominal tenderness,

steatorrhea, fluid and fecal retention, emaciation and severe diarrhea were found

only in cat 7. These results are consistent with previous observations on cats and

dogs [l, 2,6, 8, 11, 13, 23, 251. Worm burdens could not be directly related with the

extent of eosinophilia, but numbers of leukocytes fluctuated widely in both infected

and uninfected cats. The excitable nature of the cat has been related to the substantial

elevations; even 40,000 cells/ml may be normal in a cat under stress [ 191.

Peak eosinophilia was associated with maturation and oviposition of the flukes. In

other studies, C. sinensis in rabbits became patent by day 22 [25], and eosinophilia

coincided with maturation of C. sinensis in guinea pigs [20]. Eosinotactic substances

may be secreted by Opisthorchis viverrini [3], and mobilization of eosinophils followed

the migration of F. hepatica into the biliary system [15,22].

Hyperproteinemia, with elevated albumin and globulin, was seen in cat 7 (table I).

Elevated albumin could follow dehydration and shock in the acute infection. Globulin

changes reflect products of the reticulo-endothelial system; elevated ,8 globulin

is also indicative of obstructive jaundice. Both a and ,8 globulins were elevated in

rabbits infected with C. sinensis [25]. Significant changes in al, a2 and total a globulin

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784 Watson and Croll

occurred in Experiment 1. These changes generally are associated with inflammatory

reactions and occur in obstructive jaundice, probably because of increased serum

lipid [6, 181. Changes in y globulin were inconsistent in both infected and uninfected

cats. This may explain the apparent lack of resistance to re-infection seen in

Experiment 3. There was a good correlation between the albumin and globulin

change and infection (R = 0.7884; PR>R = 0.001). The a1bumin:globulin ratio was

depressed in cat 7 and there was a tendency for it to be depressed, though not

significantly, in infected cats in Experiment 1.

Leucine aminopeptidase is concentrated in the biliary epithelium and is even more

specific as an indicator of biliary disease than alkaline phosphatase. It increased

significantly in infected cats. Alanine aminotransferase (SGPT) increased signifi-

cantly between days 6 and 16 post-infection, suggesting acute hepatocellular damage,

even in the absence of clinical signs. While this is an excellent indicator of hepato-

cellular lesions, it also may be elevated in muscle or cardiac damage. Serum bilirubin

was elevated significantly only in cat 7, which had severe icterus. The lack of

conclusive hematological or serological abnormalities in metorchiasis in man [7]

probably results from the transitoriness of many of these changes. In man, the acute

clinical features of opisthorchiasis and clonorchiasis are brief [lo, 14, 21, 261.

Direct mechanical effects can be seen in histological sections. The attachment of

the suckers to the biliary epithelium, adherence of hepatocytes and inflammatory

cells to the worms, atrophy of the epithelium and the presence of host cells in the

parasite's caeca all indicate direct mechanical damage. Lesions ascribed to natural

infections of M. albidus in cats in Europe are similar to those seen in our experiments

116, 231.

Acknowledgements

The authors wish to thank the Natural Sciences and Engineering Research Council of

Canada for a grant to Neil A. Croll, which partially financed this project. Research at the

Institute of Parasitology is supported by N.S.E.R.C. and the Formation des Chercheurs et

d'Action ConcertCe du Ministere de l'Education du Quebec.

References

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2 AXELSON, R.D.: Metorchis conjunctus liver fluke infestation in a cat. Can Vet J 3359-360,

1962

3 BHAMERAPRAVATI, N.; THAMMAIRT, W.; VAJRASTHIRA, S.: Liver changes in hamsters

infected with a liver fluke of man, Opisthorchis viverrini. Am J Trop Med Hyg 27787-794,

1978

4 CHOI, D.W.; KIM, J.W.; PARK, S.B.: Laboratory findings in symptomless clonorchiasis.

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5 CHOI, W.Y.; LEE, O.R.; LEE, W.K.: Paper electrophoretic pattern of serum protein fractions

in various parasitic diseases. Kor J Parasitol 12 157-164, 1974

6 COLES, E.H.: Veterinary Clinical Pathology. W.B. Saunders Company, Toronto, 1974

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7 EATON, R.D.P.: Meforchiasis-A Canadian Zoonosis. Epidemiol Bull (National Health

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10 HARTLEY, J.P.R.; DOUGLAS, A.F.: A case of clonorchiasis in England. Br Med J 3575,

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Request reprints from T. G. Watson, c/o Regional Director, Invermay Agricultural Research

Centre, Private Bag, Mosgiel, New Zealand.

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