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* From the Division of Allergy, Pulmonary, Immunology, Critical Care and Sleep, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX.
Correspondence to: Gulshan Sharma, MD, MPH, Assistant Professor, Allergy, Pulmonary, Immunology, Critical Care, and Sleep (APICS) Division, 301 University Blvd, JSA - 5.112, UTMB, Galveston, TX 77555-0561; e-mail: gulshan.sharma{at}utmb.edu
A 57-year-old man was brought to our facility with complaints of chest and abdominal pain for 3 to 4 days. He was initially evaluated in the emergency department and found to be in mild distress secondary to the pain. His medical history was significant for hepatitis C, cirrhosis, coronary artery disease, and hypertension. His prior surgeries included three-vessel coronary artery bypass grafting and pacemaker insertion. The patient was hospitalized approximately 6 weeks earlier with an upper-GI bleed. Endoscopy performed at that time revealed a nonbleeding gastric ulcer as well as multiple gastric erosions and esophagitis. He received 2 U of packed RBCs. Serology results were positive for Helicobacter pylori, and the patient was discharged receiving metronidazole, clarithromycin, and pantoprazole. Review of systems on the current hospital admission was remarkable for fever, chills, dyspnea, anorexia, fatigue, and dark urine. He denied any travel outside of Texas in the past 5 years. He reported taking medications for BP and hyperlipidemia.
Physical examination was notable for jaundice and mild-to-moderate distress secondary to abdominal pain. Vital signs were stable, and the patient was afebrile on initial presentation. Lung fields were clear to auscultation, and heart sounds were normal but tachycardic. Abdominal examination revealed mild distention with diffuse tenderness to palpation but no rebound or guarding. Laboratory studies were remarkable for a WBC count of 6,500/µL with left shift; hemoglobin, 8 g/dL (baseline, 12 g/dL); platelets, 12,000/µL; prothrombin time, 29 s; and international normalized ratio, 2.7. Basic metabolic profile was within normal limits, but aspartate aminotransferase and alanine aminotransferase levels were elevated at 305 U/L and 84 U/L, respectively. Further laboratory evaluation revealed a haptoglobin level < 6 mg/dL, total bilirubin of 8.7 mg/dL (unconjugated, 4.2 mg/dL), and lactate dehydrogenase of 5,539 U/L. Laboratory results at the time of discharge of the previous hospitalization were as follows: hemoglobin, 11.8 g/dL; platelets, 72,000/µL, international normalized ratio, 1.4; total bilirubin, 1.8 mg/dL; and lactate dehydrogenase, 524 U/L. As the laboratory values were suggestive of hemolysis, the peripheral smear was examined for further evaluation.
What is the diagnosis?
Diagnosis: Babesiosis acquired via blood transfusion
Babesiosis is a tick-borne disease caused by hemoprotozoan parasites of the genus Babesia, resulting in an intraerythrocytic infection that can range from an asymptomatic state to life-threatening illness. Babesia microti is the most clinically important species in the United States because it is responsible for the overwhelming majority of infections. The first human case of babesiosis was described in 1957. The true prevalence is unknown because most cases are self limited and babesiosis is not a disease that is reportable to the Centers for Disease Control and Prevention. However, regional studies have demonstrated seroprevalence rates that range from 3 to 8%. Despite the rarity of its occurrence, the incidence does appear to be growing in part due to expansion of the endemic regions and migration of animal as well as human hosts. The usual manner of transmission is via a bite from the ixodid tick, which serves as the vector. The animal reservoir is the white-footed mouse. Babesiosis is predominantly a disease of the Northeast region of the United States; however, there have been cases reported in the Midwest as well as on the west coast. There are no clear endemic regions outside of the United States. Sporadic cases have been reported in Taiwan, China, Egypt, Mexico, Europe, and Africa. Although the usual mode of transmission is by means of a tick vector, there have been rare cases when the disease has been transmitted by blood transfusion.
Babesiosis is the most important transfusion-related tick-borne disease. It is second only to malaria in parasitic infections. The Babesia parasites remain viable indefinitely under normal blood bank conditions. Transmission has been reported to have occurred by transfusion of packed RBCs as well as platelets; however, there have been no reported cases of transmission after plasma transfusion. The usual scenario of transmission is donation of infected blood by an apparently healthy donor to an immunocompromised recipient resulting in systemic infection.
Clinical features range from an asymptomatic state to rapidly fatal disease. The incubation period following tick bite is usually 1 to 6 weeks. After transfusion, the period can extend up to 9 weeks. Manifestations include constitutional symptoms, hepatosplenomegaly, hemolytic anemia, congestive heart failure, renal failure, and shock with associated multiorgan failure. More severe symptoms tend to occur in those patients who are elderly, immunocompromised, or asplenic. The mortality rate has been estimated to be 5%. Routine screening of blood for babesiosis is not performed because there is currently no Food and Drug Administration-approved screening test.
Diagnosis is most often made by hematologic investigation. Given certain similarities in appearance, babesiosis is often misdiagnosed as plasmodium infection. Microscopic evaluation of thin and thick blood smears stained with Giemsa can reveal intraerythrocytic parasites either as darkly staining ring forms or as the classic tetrad formation, which is rarely seen. However, as is often the case, parasite levels may be too low to identify actual organisms under the microscope, so other serologic or molecular methods may be needed to make the diagnosis. These include indirect immunofluourescent antibody testing or the use of polymerase chain reaction. Immunofluourescent antibody results can be negative during the early course of infection and can be falsely positive with other inflammatory disease processes such as connective tissue disorders including systemic lupus erythematosus and rheumatoid arthritis. Titers of 1:256 and above usually indicate acute infection. Polymerase chain reaction testing achieves a high degree of sensitivity and can be useful when attempting to monitor treatment response.
The "gold standard" for treatment of babesiosis had been clindamycin and quinine for many years; however, given the common occurrence of side effects including tinnitus, decreased hearing, and diarrhea, the suggested combination of therapy is now atovaquone and azithromycin to be taken for a duration of 7 days. Atovaquone and azithromycin have been shown to be as effective as clindamycin and quinine but with a decreased incidence of adverse reactions. Exchange transfusion is indicated for immunosuppressed patients, high parasite loads, severe hemolysis, nonresponse to standard medical therapy, and critically ill individuals. The goal is to achieve a rapid decrease in parasitemia. The keys to management remain early recognition and implementation of appropriate therapy.
A review of 139 hospitalized cases of babesiosis between 1982 and 1993 in the state of New York was performed to identify prognostic factors associated with a poor outcome. A poor outcome in the study was defined as hospitalization ending in death, duration of hospitalization > 14 days, and ICU stay > 2 days. Multivariate analyses indicated that male sex, alkaline phosphatase > 125 U/L, and WBC count > 5,000/µL were strong predictors of outcome severity.
Clinical Course
In the case of our patient, the differential diagnosis of hemolysis and associated clinical findings in the setting of recent blood transfusion could include both immune-mediated and nonimmune-mediated phenomena. The immune-mediated processes could involve either acute or delayed hemolytic transfusion reactions. Delayed reactions typically occur within 3 weeks of transfusion. Nonimmune-mediated phenomena resulting in RBC destruction include thermal injury, osmotic injury, mechanical injury, infection, congenital hemolytic anemia, acquired hemolytic anemia, or drugs.
Review of the peripheral smear by the hematologist was notable for the presence of intraerythrocytic parasites. A low-power view (Fig 1 ) revealed several ring-shaped forms (piroplasms) within the erythrocytes. High-power magnification (Fig 2 ) demonstrated the classic tetrad, or Maltese cross formation, that is pathognomonic for babesiosis. Further serologic testing was ordered for confirmation, and the patient was started on multidrug treatment with atovaquone and azithromycin. The severe thrombocytopenia was likely due to disseminated intravascular coagulation in addition to the baseline cirrhosis. The patient was transferred to the ICU with the development of fever, alteration in mental status, and increasing respiratory distress. He subsequently required intubation, vasopressor support, and initiation of continuous venovenous hemodialysis. Arrangements were also made to utilize exchange transfusion therapy. Despite aggressive therapy, the patient’s condition rapidly deteriorated. Resuscitative measures were unsuccessful, and the patient died. The cause of death was presumed to be septic shock with multiorgan failure due to babesiosis.
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Clinical Pearls
Footnotes
Neither of the authors has a financial relationship with any commercial entity that may have an interest in the content of this article.
Received for publication November 21, 2006. Accepted for publication December 19, 2006.
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