first case of (imported) babesiosis diagnosed in...

First case of (imported)babesiosis diagnosed

in Canada

Dennis Kunimoto MD FRCPC1, Kevin Krause MD CCFP

2, Doug Morrison MD FRCPC3

Babesiosis is an infection caused by a protozoa that para-

sitizes erythrocytes resulting in a malaria-like syndrome.

Although an important disease of cattle, it can cause signifi-

cant disease in humans. In North America, people have ac-

quired the disease on the islands off the northeast coast of the

United States, the northeast mainland, the upper midwest and

the west coast. With an increasingly mobile population, dis-

eases such as this are being seen outside of their endemic ar-

eas or areas of acquisition. To our knowledge, this is the first

case of babesiosis diagnosed in Canada.

CASE PRESENTATIONA 66-year-old male from Connecticut presented to a physi-

cian in Jasper, Alberta on September 5, 1996, complaining of a

one-week history of fever and chills. He also complained of fa-

tigue, loose stools alternating with constipation, abdominal

distension and extensive rigors.

He has a vacation home on Block Island off the coast of

Rhode Island where he spent the month of July. He had toured

Alaska and had been returning through the Canadian Rockies

when he developed his symptoms. He had not travelled out-

side the United States and Canada in his lifetime.

Temperature at presentation was 37.6°C. When examined,

there were no abnormalities other than hyperactive bowel

sounds. Specifically, there was no lymphadenopathy or hepa-

tosplenomegaly. Complete blood cell count showed a white

count of 4.9×109/L with a normal differential and hemoglobin

of 124 g/L. Platelets were low at 53×109/L. A peripheral blood

film was reviewed because of the thrombocytopenia, and in-

traerythrocytic protozoa were noted in about 1% of erythro-

Can J Infect Dis Vol 9 No 6 November/December 1998 387

CASE REPORT

1Department of Medical Microbiology and Immunology, University of Alberta, Edmonton; 2Dynacare Kasper Medical Laboratories, Edmonton;3Jasper, Alberta

Correspondence and reprints: Dr Dennis Kunimoto, 1-41 Medical Sciences Building, Department of Medical Microbiology and Immunology,

University of Alberta, Edmonton, Alberta T6G 2H7. Telephone 403-492-6781, fax 403-492-7521, e-mail [email protected]

Received for publication October 22, 1997. Accepted January 21, 1998

D Kunimoto, K Krause, D Morrison. The first reported case of (imported) babesiosis diagnosed in Canada. Can JInfect Dis 1998;9(6):387-389.

This paper describes the first case of babesiosis diagnosed in Canada. This case highlights the need for clinicians to be

aware of diseases that may be endemic elsewhere and the importance of a travel history in a patient’s assessment.

Key Words: Babesiosis, Intraerythryocytic, Protozoa

Premier cas rapporté d’une importation de babésiose diagnostiquée au Canada

RÉSUMÉ : Le présent article décrit le premier cas de babésiose diagnostiquée au Canada. Ce cas souligne le besoin pour

les cliniciens de connaître les maladies qui peuvent être endémiques dans d’autres pays et l’importance des antécédents

de voyage dans l’évaluation des patients.

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cytes. Initially, the hematopathologist felt that this repre-

sented Plasmodium falciparum, although the appearance was

not entirely typical (Figure 1). However, on reviewing the pati-

ent’s history, this diagnosis was felt to be quite unlikely clini-

cally, and the hematopathologist was asked to review the

slides again. This time a diagnosis of babesiosis was made.

The following day the patient had further smears and blood

work done. Urinalysis showed proteins were 0.3 g/L and a

trace of leukocytes; the sample was positive for ketones and

nitrite. Creatinine levels and liver panel were normal except

for a bilirubin of 25 mol/L. Haptoglobin was low at less than

0.06 g/L. Smears confirmed the diagnosis of babesiosis. The

patient was treated with seven days of clindamycin 600 mg tid

and quinine 650 mg tid. He tolerated this with difficulty due to

gastrointestinal adverse effects. However, he completed his

course and had been symptom-free for seven months. Acute

serum sent to the Centers for Disease Control and Prevention,

Atlanta, Georgia showed a titre of 1/64 for Babesia microti.

DISCUSSIONBabesia are the commonest intraerythrocytic parasite of

mammals, with about 100 species known (1). These parasites

are usually transmitted by ticks of the Ixodes genus. The tick

larvae usually acquire the parasites while feeding on animal

hosts and commonly transmit babesial sporozoites to humans

while in the nymph stage of development. Mature trophozoi-

tes reproduce in erythrocytes by asynchronous asexual bud-

ding into two or four daughters, which damage the membrane

as they exit the erythrocyte. However, the exact mechanism of

hemolysis is unknown.

Babesiosis was the first disease recognized to be transmit-

ted by an arthropod vector in 1893 (2). The first human infec-

tion with babesia was described in Yugoslavia in 1957 in a

farmer who died of fulminant hemolytic anemia (3). The first

reported case of babesiosis in the United States was in Califor-

nia in 1966 (4). Since then, several hundred cases in the

United States have been recognized, primarily from endemic

areas in the northeast such as Nantucket Island, Martha’s

Vineyard and Cape Cod, Massachusetts; Block Island, Rhode

Island; Shelter Island and Fire Island, New York; and Con-

necticut. Human infection occurs mainly in the late spring to

early fall when tick exposure is greatest. However, most pa-

tients do not recall a tick bite because nymphs are only 1 to

2 mm long, tan in color and are easily missed. The European

form of babesiosis is due to Babesia bovis or Babesia diver-

gens, which infect cattle, while in the northeast United States

babesiosis is caused by B microti, which usually infects ro-

dents. Babesiosis from the west coast of the United States is

due to a species closely related to the canine pathogen Babesia

gibsoni (5). Clinically, babesia infection in the United States is

often asymptomatic to mild, occurs in normal hosts and is

rarely fatal in contrast with the European form, where up to

84% of patients are asplenic with a high mortality rate (6).

The compact ring forms of B microti can easily be mistaken

for P falciparum malaria (7). The classic tetrad of rings (Mal-

tese cross) described in babesiosis can be difficult to find.

Useful discriminating features suggesting babesiosis in-

clude the lack of pigment (hemozoin), the presence of a cen-

tral cytoplasmic vacuole and the absence of intermediate

stages such as shizonts or gametocytes (1). Of course the lack

of travel to a malaria endemic region, history of travel or resi-

dence in a babesia endemic area, or the history of a recent tick

bite should raise the clinical suspicion of babesiosis, as it did

in this case. A transfusion history is also of importance be-

cause asymptomatic individuals infected with babesia may

donate blood, unknowingly transmitting the parasite to the

recipient.

The incubation period for babesiosis is one to six weeks,

which is consistent with the patient leaving Block Island four

weeks earlier, although the incubation period has been re-

ported to be as long as three months (6). Babesiosis is also en-

demic in Connecticut (8); however this patient’s only rural

exposure was on Block Island. Although babesiosis has been

reported from the west coast of the United States (5), patients

infected with this west coast species tend to be serologically

positive for B gibsoni but negative for B microti. As the tick

vector is Ixodes dammini, the same vector for Borrelia burg-

dorferi (Lyme disease), it is not surprising that over 50% of pa-

tients from the northeastern United States with one infection

may have serological evidence of coinfection (9). In addition,

recent serosurveys indicate coinfection with ehrlichia also oc-

curs (10). The areas of babesiosis endemicity appear to be

growing. It may be only a matter of time before all areas en-

demic for Lyme disease will also be endemic for babesiosis,

and, therefore, there may eventually be endemic areas of

babesiosis in Canada.

When symptomatic, the clinical presentation is nonspe-

cific, consisting of fever, rigors, headache, fatigue, nausea,

myalgias and abdominal pain (1). Physical findings include

fever, hepatomegaly, petechia and ecchymosis. Laboratory

data may show thrombocytopenia, low hematocrit, evidence

of hemolysis with increased reticulocytes, anemia, low hapto-

globin, elevated transaminases, proteinuria and hemoglobin-

uria. With a history of a tick bite, Lyme disease, ehrlichiosis,

babesiosis and even the spotted fever rickettsioses must be

considered depending on the exposure history. The diagnostic

388 Can J Infect Dis Vol 9 No 6 November/December 1998

Kunimoto et al

Figure 1) An erythrocyte containing a Babesia microti ring

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Black 133 lpi at 45 degrees

test for babesiosis is a peripheral smear demonstrating intra-

cellular parasites. Serology is very specific and is helpful for

epidemiology and retrospective confirmation (11).

Most infections with B microti appear to be subclinical;

however, symptomatic infections are more likely in asplenic

patients, individuals with pre-existing clinical disease and in-

dividuals over the age of 50 years. In one population survey,

age was the strongest predictor of symptomatic disease (12).

In immunocompetent patients who are symptomatic, disease

is rarely life-threatening but can be very severe, warranting

treatment. The recommended treatment is clindamycin 600

mg tid and quinine 650 mg tid orally for seven days. This

treatment was fortuitously discovered when a patient with

babesiosis was treated for what was initially thought to be

transfusion-acquired malaria unresponsive to choroquine (13).

For extremely ill patients with a high parasite load (more than

10%), exchange blood transfusion can be lifesaving (1). In our

case, the patient was moderately ill, and although his disease

may have been self-limited, we felt it prudent to treat him be-

cause he was continuing his drive back to Connecticut.

CONCLUSIONClinicians need to be aware of diseases such as babesiosis

that may be endemic elsewhere. Because of our mobile popu-

lation, a thorough travel history is crucial, not only for return

travellers, but for visitors to our locales.

ADDENDUMBetween the time of acceptance of this manuscript and publi-

cation, another patient with babesiosis, concurrently infected

with Lyme disease, was reported in Ontario; this patient was di-

agnosed in July 1997 (14). Therefore, although that report was

published first, this present case is a report of the first case diag-

nosed in Canada.

REFERENCES1. Boustani MR, Gelfand JA. Babesiosis. Clin Infect Dis

1996;22:611-5.2. Smith T, Kilborne FL. Investigation into the nature, causation,

and prevention of southern cattle fever. US Dept Agr Bur AnimIndust Bull 1893;1:109-76.

3. Skrabalo Z, Deanovi Z. Piroplasmosis in man: report on a case.Doc Med George Trop 1957;9:11-6.

4. Scholtens RG, Braff EH, Healey GA, Gleason N. A case ofbabesiosis in man in the United States. Am J Trop Med Hyg1968;17:810-3.

5. Quick RE, Herwaldt BL, Thomford JW, et al. Babesiosis inWashington State: a new species of babesia? Ann Intern Med1993;119:284-90.

6. Pruthi RK, Marshall WF, Wiltsie JC, Persing DH. Humanbabesiosis. Mayo Clin Proc 1995;70:853-62.

7. Loutan L, Rossier J, Zufferey G, et al. Imported babesiosisdiagnosed as malaria. Lancet 1993;342:749. (Lett)

8. Krause PJ, Telford SR, Ryan R, et al. Geographical and temporaldistribution of babesial infection in Connecticut. J Clin Microbiol1991;29:1-4.

9. Benach JL, Coleman JL, Habicht GS, MacDonald A, Grunwaldt E,Giron JA. Serological evidence for simultaneous occurrences ofLyme disease and babesiosis. J Infect Dis 1985;152:473-7.

10. Magnarelli LA, Dumler JS, Anderson JF, Johnson RC, Fikrig E.Coexistence of antibodies to tick-borne pathogens of babesiosis,ehrlichiosis, and Lyme borreliosis in human sera.J Clin Microbiol 1995;33:3054-7.

11. Krause PJ, Telford SR, Ryan R, Conrad PA, Wilson M, ThomfordJW. Diagnosis of babesiosis: evaluation of a serologic test for thedetection of Babesia microti antibody. J Infect Dis1994;169:923-6.

12. Meldrum SC, Birkhead GS, White DJ, Benach JL, Morse DL.Human babesiosis in New York State: an epidemiologicaldescription of 136 cases. Clin Infect Dis 1992;15:1019-23.

13. Wittner M, Rowin KS, Tanowitz HB, et al. Successfulchemotherapy of transfusion babesiosis. Ann Intern Med1982;96:601-4.

14. dos santos C, Kanin K. Concurrent babesiosis and Lymedisease diagnosed in Ontario. Can Commun Dis Rep1998;24:97-101.

Can J Infect Dis Vol 9 No 6 November/December 1998 389

Babesiosis in Canada

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