Babesiosis
Babesiosis: Excerpt from The 5-Minute Pediatric Consult
Oluwakemi B. Badaki, MDFrances M. Nadel, MD, MSCE
Babesiosis - BASICS
Babesiosis - description
- Human babesiosis is a tick-borne malarialike illness characterized by fever, malaise, and hemolytic anemia.
- Most infected individuals are asymptomatic.
Babesiosis - general prevention
- Prevention begins with avoidance of tick bites.
- Simple measures include wearing long-sleeved shirts and long pants, with pants tucked into the socks in tick-infested areas.
- Avoid endemic regions during the peak months of May to September.
- Light clothing will make ticks easier to see.
- Spraying the bottoms of one’s pants with a tick repellent may also be helpful.
- Children and dogs should be inspected for ticks after being outside.
- High-risk individuals may want to avoid endemic areas from May to September.
- Currently, there is no universal laboratory screening of blood products.
- Prophylaxis is not recommended after a tick bite.
- Currently, there is no vaccine available.
Babesiosis - epidemiology
- The 1st human case in the US was reported from California in 1966.
- Transmission usually occurs in the summer and early fall.
- In the US, most cases have been reported from the Northeast, Midwest, and Pacific Coast.
- Endemic areas include Rhode Island, Massachusetts, and New York.
- Cases have been reported in New Jersey, Maryland, Virginia, Georgia, Wisconsin, and Minnesota.
Babesiosis - incidence
There were >450 confirmed cases of human babesiosis diagnosed in the US between 1968 and 1993.
Babesiosis - prevalence
Difficult to ascertain because asymptomatic infection appears to be common in endemic areas.
- It has been reported, for instance, that seroprevalence is as high as 9% in some endemic areas of Rhode Island.
Babesiosis - risk factors
- Asplenia (functional or anatomic)
- Malignancy
- HIV/AIDS
- Immunosuppressive medications
- Primary immunodeficiency syndrome
- Extremes of age, especially age >50 years
Babesiosis - genetics
There is no known genetic predisposition.
Babesiosis - pathophysiology
- A bite from an infected tick transmits the protozoa.
- Incubation period:
- Usually 1–4 weeks
- Can be as long as 9 weeks
- Infection of the erythrocyte causes membrane damage and lysis, which promotes adherence to the endothelium and microvascular stasis.
- The spleen plays an important role in decreasing the protozoal load, through antibody production and filtering abnormally shaped infected red blood cells.
Babesiosis - etiology
- Human babesiosis is caused by the intraerythrocytic parasite of the Babesia genus.
- In the northeast US, Babesia microti is the most commonly isolated agent.
- Babesia divergens is the responsible agent in Europe.
- WA-1 and MO-1 cause babesiosis in western US and Missouri, respectively.
- Ixodes dammini (Ixodes scapularis), the same tick responsible for Lyme disease, is the invertebrate vector for B. divergens.
- Rarely, the disease has been acquired through transplacental/perinatal transmission or through transfusion of contaminated blood products.
- Babesiosis is the most common tick-borne disease transmitted by contaminated blood transfusions
Babesiosis - associated conditions
It is estimated that 11–23% of patients have concurrent Lyme disease.
Babesiosis - DIAGNOSIS
Babesiosis - signs & symptoms
Babesiosis - history
- Few patients recall a tick bite.
- Patients live in or have recently traveled to an endemic region.
- Initial symptoms begin 1–4 weeks after the tick bite and are vague. They may include progressive fatigue, malaise, headaches, and anorexia, accompanied by intermittent fevers as high as 40°C.
- Chills, myalgias, and arthralgias may follow these symptoms.
- Less common complaints include cough, sore throat, abdominal pain, and emotional lability.
Babesiosis - physical exam
- Fever is often the only finding.
- Mild conjunctival injection and pharyngeal erythema
- Some may have mild hepatomegaly and/or splenomegaly.
- Jaundice or hematuria may also be seen.
- Petechiae and ecchymosis occur in rare cases, most often in the presence of severe illness with associated shock and/or DIC.
Babesiosis - tests
Babesiosis - lab
- Giemsa- or Wright-stained thick and thin blood smears may demonstrate the intraerythrocytic ring form:
- This is often confused with the ring form of Plasmodium falciparum, the etiologic agent of malaria.
- Rarely, the pathognomonic “Maltese Cross” forms of the Babesia parasite may also be seen on the blood smear
- Multiple smears should be performed as initial smears may be falsely negative.
- Indirect immunofluorescent assay:
- Antigen-specific for B. microti
- In endemic areas, the test has a sensitivity of 91% and a specificity of 99%.
- Can be used when blood smears are negative
- In general, a titer = 1:64 indicates exposure.
- Titer = 1:256 suggests acute infection.
- There is little correlation between titer levels and severity of disease.
- Immunoglobulin levels decline rapidly within months of recovery.
- Polymerase chain reaction is highly sensitive and specific.
- Isolation of the parasite can be done by intraperitoneal injection of a patient’s blood into a golden hamster, but results take weeks.
- Other tests: Most of the abnormal routine test results are the result of hemolysis.
- Urinalysis:
- Proteinuria
- Hemoglobinuria
- CBC:
- Normal leukocyte count/leukopenia
- Normocytic/normochromic anemia
- Thrombocytopenia
- Atypical lymphocytosis
- Reticulocytosis
- Possible positive Coombs test
- Elevated ESR
- Liver function tests: Elevated bilirubin, lactate dehydrogenase, and liver transaminases
- In asymptomatic patients, these tests are often normal.
False negatives:
- The blood smears may not demonstrate the protozoan at low levels of parasitemia.
- Serologic false positives for B. microti include cross-reactivity with other Babesia sp. or malarial organisms.
- Theoretical serologic false positives for WA1:
- Rheumatoid factor
- Antinuclear antibody
- Antibody to Toxoplasma gondii
Babesiosis - differencial diagnosis
- Nonspecific viral syndrome
- Malaria
- Influenza
- Lyme disease
- Ehrlichiosis
Babesiosis - TREATMENT
Babesiosis - general measures
Those with mild clinical disease usually recover without treatment.
Babesiosis - special therapy
- For life-threatening infections, exchange transfusion has been successful.
- Progressive respiratory distress may require mechanical ventilation.
Babesiosis - medication
Babesiosis - first line
Asplenic, immunodeficient, or symptomatic patients should be treated with clindamycin and quinine.
- The pediatric dose of clindamycin is 20–40 mg/kg/d divided into 3 doses for 7–10 days.
- The adult dose is 600 mg PO t.i.d. or 1,200 mg IV b.i.d. for 7–10 days.
- Quinine is dosed 10–25 mg/kg/d divided into 3 doses for 7–10 days.
- Adult dose is 650 mg PO t.i.d. for 7–10 days.
Babesiosis - second line
- Combination of atovaquone and azithromycin:
- Has similar treatment effectiveness with fewer side effects (such as vertigo, tinnitus and GI upset) than clindamycin and quinine in adults
- Use of atovaquone and azithromycin has not been studied in the pediatric population; clindamycin and quinine are the recommended treatment choice for symptomatic children.
- In areas endemic for Lyme disease and Ehrlichiosis, consider adding doxycycline until lab confirmation of absence of either disease in the patient with Babesiosis.
Babesiosis - FOLLOW UP
When to expect improvement:
- Some improvement of symptoms should be noted within 24–48 hours of onset of therapy.
- Those who are only mildly affected usually have resolution of their symptoms over a few weeks.
- For severely affected and immunodeficient patients, the convalescent period may be as long as 18 months.
- In untreated asymptomatic individuals, parasitemia may persist for months to years.
- Long-term complications are rare.
- Recrudescence has been reported.
- Signs to watch for:
- Respiratory distress, especially after treatment has begun
- Pancytopenia and lymphadenopathy: May indicate the development of hemophagocytic syndrome
- Pitfalls:
- Children who are from endemic areas and have an acute febrile illness may be misdiagnosed with a nonspecific viral illness
- One should be suspicious for a coinfection with Lyme disease or Ehrlichiosis (Human anaplasmosis) in those who are not responding to standard therapy.
- Delayed recognition of this uncommon disease may be life threatening in the immunocompromised patient.
- In endemic areas, babesiosis should be considered in a posttransfusion febrile illness in at-risk populations.
Babesiosis - complications
- Rarely fatal in the US
- Pancytopenia and overwhelming secondary bacterial sepsis may occur.
- Serious and fulminant complications have been described:
- Pulmonary edema and adult respiratory distress syndrome, often happening after treatment has begun
- CHF
- Renal failure
- Hemophagocytic syndrome/disseminated intravascular coagulation
- Seizures/coma
- Those coinfected with Lyme disease are susceptible to more severe disease and complications.
Babesiosis - bibliography
- Aguero-Rosenfeld ME. Laboratory aspects of tick-borne diseases: Lyme, human granulocytic ehrlichiosis and babesiosis. Mount Sinai J. Med. 2003;70:197–206.
- Buckingham SC. Tick-borne infections in children: Epidemiology, clinical manifestations, and optimal management strategies. Paediatr Drugs. 2005;7(3):163–176.
- Filbin MR, Mylonakis EE, Callegari L, et al. J Emerg Med. 2001;20(1):21–24.
- Homer MJ, Aguilar-Delfin I, Telford SR 3rd, et al. Babesiosis. Clin Microbiol Rev. 2000;13(3):451–469.
- Krause PJ. Babesiosis. Med Clin North Am. 2002;86(2):361–373.
- Krause PJ. Babesiosis diagnosis and treatment. Vector Borne Zoonotic Dis. 2003;3(1):45–51.
- Krause PJ. Babesiosis. Med Clin North Am. 2002;86:361–373.
- McGinley-Smith DE, Tsao SS. Dermatoses from ticks. J Amer Acad Dermatol. 2003;49:363–392; quiz 393–396.
- Pantanowitz L, Telford SR 3rd,, Cannon ME. The impact of babesiosis on transfusion medicine. Transfus Med Rev. 2002;16(2):131–143.
- Wormser GP, Dattwyler RJ, Shapiro ED, et al. The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: Clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006;43(9):1089–1134.
Babesiosis - CODES
Babesiosis - icd9
088.82 Babesiosis
Babesiosis - FAQ
- Q: How long does a tick have to be attached for infection to occur?
- A: In general, successful transmission requires at least 24 hours of attachment.
- Q: How should a tick be removed?
- A: The tick should be grasped with forceps as close to its head as possible and pulled straight up. If possible, it should be saved for identification.
- Q: Does infection confer lifetime immunity?
- A: Reinfection is possible.
Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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