Case Detection and Definition

We learned of additional babesiosis cases because they were reported to the New Jersey Department of Health and Senior Services or because health-care providers contacted the Centers for Disease Control and Prevention (CDC) about the diagnosis or treatment of babesiosis. Although babesiosis is not a nationally notifiable disease, some states have made cases of babesiosis reportable. Cases became reportable in New Jersey in 1985; however, reporting was discontinued in 1990 because no cases had been reported. Reporting was reinstated in 1995, and 1997 was the first year in which cases were reported to the health department.

We defined a potential case of babesiosis as an infection occurring in a symptomatic person whose illness was consistent with babesiosis, most likely was acquired in New Jersey, and most likely resulted from a tick bite rather than a blood transfusion. In addition, supporting laboratory data had to be provided and include at least one of the following: identification by light microscopy of intraerythrocytic Babesia parasites in a peripheral blood smear, isolation of the parasite from a whole blood specimen (by inoculating hamsters [Mesocricetus auratus] intraperitoneally and examining blood smears obtained weekly by tail snip for up to 2 months), demonstration of B. microti DNA in a whole blood specimen by polymerase chain reaction (PCR) analysis at a reference laboratory, or demonstration of a Babesia-specific antibody titer of at least 1:256 with an indirect fluorescent antibody assay for total immunoglobulin (Ig) G. If only serologic data met the diagnostic criteria, the case was considered probable rather than confirmed.

Case Report

Figure 1

Figure 1. Map of New Jersey showing its 21 counties. The eight counties in which reported cases of babesiosis were acquired from 1993 through 2001 are shaded in gray (the darker the gray,...

A previously healthy 53-year-old woman was admitted to a community hospital on June 24, 1999, because she had 1 week of fever (38.9°C–39.4°C), rigors, a nonproductive cough, an occipital headache, and increasing malaise. Three days before her hospitalization, she started therapy with cefuroxime axetil for presumed bronchitis but did not improve. She had a >50 pack-year history of smoking and drank two to three beers per day. She lived in Burlington County (Figure 1) in southcentral New Jersey and had not traveled outside the county recently. Although she did not recall recent exposure to deer ticks, she occasionally had seen deer in her backyard and she gardened frequently.

On admission to the hospital, she had a temperature of 39.2°C, a blood pressure level in the 80/60 mm Hg range, and otherwise unremarkable results on physical examination. She was anemic and thrombocytopenic, with elevated total bilirubin and lactate dehydrogenase values (Table). On the basis of a blood smear from June 24, which showed intraerythrocytic ring forms in approximately 5% of the erythrocytes on her peripheral blood smear, treatment for babesiosis was begun on June 25. The treatment included intravenous clindamycin, 900 mg three times a day, and 650 mg oral quinine three times a day; and she was transfused with two units of packed erythrocytes. Also on June 25, hypoxic respiratory failure developed, and she was intubated. A chest radiograph showed diffuse alveolar infiltrates, which were attributed to the adult respiratory distress syndrome (ARDS).

On June 28, she was transferred to the Hospital of the University of Pennsylvania. When admitted, her blood pressure was 84/52 mm Hg, despite therapy with dopamine. She continued therapy for babesiosis for a total of 15 days (the dose of clindamycin was decreased to 600 mg three times a day on June 28). Although the level of parasitemia had decreased to 0.3% by June 29, she had ongoing hemolysis and received six more units of packed erythrocytes during her hospital stay (Table). No parasites were noted on a blood smear on July 9, the last day of antibabesial therapy. She had been successfully weaned from inotropic blood-pressure support on July 2 and underwent extubation on July 4.

Additional laboratory testing at CDC provided further evidence that she was infected with B. microti. Serum specimens assayed in parallel, in serial fourfold dilutions, by indirect fluorescent antibody testing for antibody to B. microti (4), had titers of 1:1,024 (June 30, 1999) and 1:16 (July 16, 2000). In addition, PCR analysis of whole blood from June 30, 1999, by using B. microti-specific primers (5), confirmed she was infected with B. microti. Serologic testing performed at the Hospital of the University of Pennsylvania by enzyme immunoassay for antibody to Borr. burgdorferi was negative.

Complications during her hospitalization unrelated to babesiosis included nosocomial pneumonia, acute tubular necrosis from hypoperfusion, bilateral deep venous thromboses, pulmonary embolism, and thrombocytopenia temporally associated with the initiation of heparin therapy (Table). On July 23, after 30 days in the hospital, she was sent home. She was continuing to do well as of October 2002.

Composite Data

The 40 cases in our analyses included the case described above, the three cases previously described by Eskow et al. (2), and 36 other cases. We did not include six other reported tick-borne cases that occurred in New Jersey residents, because the laboratory data did not meet our criteria or information about the probable state in which infection was acquired was not known or provided.

Figure 2

Figure 2. The number of reported cases of babesiosis acquired each year, 1993–2001.

The number of reported cases of babesiosis increased over time (Figure 2); 28 (70.0%) of the 40 cases occurred in 2000 or 2001. The 40 cases were acquired in eight (38.1%) of the state’s 21 counties (Figure 1). Burlington County, on the inner coastal plain, and Ocean County, on the outer coastal plain, which are neighboring counties in southcentral New Jersey, accounted for 25 (62.5%) of the 40 cases; these two counties are the 7th (Ocean) and 10th (Burlington) most populous counties in the state. None of the cases were acquired in the northernmost or southernmost counties of New Jersey.

Most of the cases were in elderly persons (median age, 67 years; range, 11–87 years). Over half of the cases (22 [55.0%]) were in male patients. The median date of diagnosis was July 20 (range, June 10–September 9; n=36). Two patients (5.0%) died: an 86-year-old man with multisystem organ failure and an 80-year-old man with ARDS. The patient whose case we described here also developed ARDS.

The following information about the patients was not collected systematically. However, three patients were reported to be asplenic, 18 to have recalled tick bites, 34 to have been hospitalized, and three to have had Lyme disease (no details available). Underlying conditions included HIV infection in one patient, who had a CD4 count of 50; diabetes in five patients; a history of breast or prostate cancer in three patients (no details available); and a condition that led to chemotherapy in one person (no details available).

Various types of laboratory tests were used to diagnose the 40 babesiosis cases. Not all patients were tested with the same methods; however, 34 patients had positive blood smears; for 27 of these patients, the positive smear was the only laboratory result that met our diagnostic criteria. All three cases reported by Eskow et al. were in patients who had negative blood smears (2). One of the two patients who had whole blood inoculated into hamsters had positive results (i.e., the hamsters became parasitemic). Four patients had positive PCR results from a reference laboratory; for one of these patients, these results were the only ones that met our diagnostic criteria. Twelve patients had serologic data that met our criteria; for four patients, these data were the only ones that met our diagnostic criteria. These cases were considered probable rather than confirmed. CDC confirmed the diagnosis of Babesia infection in 11 (27.5%) of the 40 cases; specimens from the other 29 case-patients were not sent to CDC.