You can now download VisualDx for your iOS and Android devices. Launch the VisualDx app from your device and sign in using your VisualDx personal account username and password.
CME Certification
Sign in with your personal account to earn and claim CME credits through VisualDx. Credits can be earned by building a differential or looking up a diagnosis.
Christine Ahn MD
Carl Allen DDS, MSD
Brandon Ayres MD
Howard P. Baden MD
Robert Baran MD
Keira Barr MD
Gregory J. Basura MD, Ph.D
Donald Belsito MD
Jeffrey D. Bernhard MD
Jesse Berry MD
Victor Blanco MD
Benjamin R. Bohaty MD
William Bonnez MD
Sarah Brenner MD
Robert A. Briggaman MD
Robert Brodell MD
Roman Bronfenbrener MD
Walter Brooks MD
William Buckley MD
Philip Bulterys MD, PhD (candidate)
Susan Burgin MD
Sonya Burton MD
Sean P. Bush MD, FACEP
Jeffrey Callen MD
Scott Camazine MD
Michael Cardwell
Shelley D. Cathcart MD
Robert Chalmers MD, MRCP, FRCP
Chia-Yu Chu MD, PhD
Flavio Ciferri MD
Maria Rosa Cordisco MD
Noah Craft MD, PhD
John T. Crissey MD
Harold E. Cross MD, PhD
Charles E. Crutchfield III MD
Adriana Cruz MD
Donna Culton MD, PhD
Bart J. Currie MBBS, FRACP, DTM&H
Chicky Dadlani MD
Alexander Dane DO
C. Ralph Daniel III MD
Thomas Darling MD, PhD
William Delaney MD
Damian P. DiCostanzo MD
Ncoza Dlova MD
James Earls MD
Libby Edwards MD
Melissa K. Egge MD
Charles N. Ellis MD
Rachel Ellis MD
David Elpern MD
Nancy Esterly MD
Stephen Estes MD
E. Dale Everett MD
Janet Fairley MD
David Feingold MD
Jennifer J. Findeis-Hosey MD
Benjamin Fisher MD
Henry Foong MBBS, FRCP
David Foster MD, MPH
Brian D. Foy PhD
Michael Franzblau MD
Vincent Fulginiti MD
Sunir J. Garg MD, FACS
Kevin J. Geary MD
Lowell Goldsmith MD, MPH
Sethuraman Gomathy MD
Bernardo Gontijo MD, PhD
Kenneth Greer MD
Kenneth G. Gross MD
Alan Gruber MD
Nathan D. Gundacker MD
Akshya Gupta MD
Vidal Haddad MSC, PhD, MD
Edward Halperin MD, MA
Ronald Hansen MD
John Harvey
Rizwan Hassan MD
Michael Hawke MD
Jason E. Hawkes MD
Peter W. Heald MD
David G. Hicks MD
Sarah Hocker DO
Ryan J. Hoefen MD, PhD
Li-Yang Hsu MD
William Huang MD
Sanjana Iyengar MD
Alvin H. Jacobs MD
Saagar Jadeja MD
Shahbaz A. Janjua MD
Joshua J. Jarvis MD
Kit Johnson
Zachary John Jones MD
Robert Kalb MD
A. Paul Kelly MD
Henry Kempe MD
Loren Ketai MD
Sidney Klaus MD
Ashwin Kosambia MD
Jessica A. Kozel MD
Carl Krucke
Mario E. Lacouture MD
Joseph Lam MD
Alfred T. Lane MD
Edith Lederman MD
Nahyoung Grace Lee MD
Pedro Legua MD, PhD
Robert Levin MD
Bethany Lewis MD
Sue Lewis-Jones FRCP, FRCPCH
Taisheng Li MD
Christine Liang MD
Shari Lipner MD, PhD
Adam Lipworth MD
Jason Maguire MD
Mark Malek MD, MPH
Jere Mammino DO
Ricardo Mandojana MD
Lynne Margesson MD
Thomas J. Marrie MD
Maydel Martinez MD
Ralph Massey MD
Patrick McCleskey MD
Karen McKoy MD
Thomas McMeekin MD
Josette McMichael MD
Somchai Meesiri MD
Joseph F. Merola MD
Mary Gail Mercurio MD
Anis Miladi MD
Larry E. Millikan MD
Dan Milner Jr. MD
Zaw Min MD
Stephanie Montero
Alastair Moore MD
Keith Morley MD
Dean Morrell MD
Samuel Moschella MD
Rehan Naseemuddin MD
Taimor Nawaz MD
Vic Newcomer MD
John Nguyen MD
Matilda Nicholas MD
Thomas P. Nigra MD
Steven Oberlender MD, PhD
Maria Teresa Ochoa MD
Daniel C. Oppenheimer MD
Art Papier MD
Lawrence Parish MD
Tanner Parrent MD
Mukesh Patel MD
Lauren Patty-Daskivich MD
David Peng MD, MPH
Robert Penne MD
Nitipong Permpalung MD
Miriam Pomeranz MD
Doug Powell MD
Harold S. Rabinovitz MD
Christopher J. Rapuano MD
Sireesha Reddy MD
Angela Restrepo MD, PhD
Bertrand Richert MD, PhD
J. Martin Rodriguez, MD, FACP
Theodore Rosen MD
Misha Rosenbach MD
Scott Schiffman MD
Robert H. Schosser MD
Glynis A. Scott MD
Carlos Seas MD, MSc
Deniz Seçkin MD
Daniel Sexton MD
Paul K. Shitabata MD
Tor Shwayder MD, FAAP, FAAD
Elaine Siegfried MD
Gene Sienkiewicz MD
Christye Sisson
Philip I. Song MD
Mary J. Spencer MD, FAAP
Lawrence B. Stack MD
Sarah Stein MD
William Van Stoecker MD
Frances J. Storrs MD
Erik J. Stratman MD
Lindsay C. Strowd MD
Erika Summers MD
Belinda Tan MD, PhD
Robert Tomsick MD
Hensin Tsao MD, PhD
Richard P. Usatine MD
Jenny Valverde MD
Vishalakshi Viswanath MD
Susan Voci MD
Lisa Wallin ANP, FCCWS
Douglas Walsh MD
Ryan R. Walsh MD
George Watt MD
Clayton E. Wheeler MD
Sally-Ann Whelan MS, NP, CWOCN
Jan Willems MD, PhD
James Henry Willig MD, MPH
Karen Wiss MD
Vivian Wong MD, PhD
Sook-Bin Woo MS, DMD, MMSc
Jamie Woodcock MD
Stephen J. Xenias MD
Nathaniel Yohannes
Lisa Zaba MD
Vijay Zawar MD
Bonnnie Zhang MD
Carolyn Ziemer MD
Jeffrey P. Zwerner MD, PhD
Organizations
Am. Journal of Trop. Med & Hygiene
Armed Forces Pest Management Board
Blackwell Publishing
Bugwood Network
Centers For Disease Control and Prevention
Centro Internacional de Entrenamiento e Investigaciones Mèdicas (CIDEIM)
Dermatology Online Journal
East Carolina University (ECU), Division of Dermatology
International Atomic Energy Agency
Massachusetts Medical Society
NYU Department of Dermatology
Oxford University Press
Radiological Society of North America
Washington Hospital Center
Wikipedia
World Health Organization
Babesiosis is a tick-borne zoonotic infection caused by protozoa of the genus Babesia. The major tick vector in the United States is Ixodes scapularis (blacklegged ticks, or deer ticks), which can also transmit Lyme disease, human granulocytic anaplasmosis (formerly known as human granulocytic ehrlichiosis), and Borrelia miyamotoi. Concomitant infections with these pathogens have been described. The main animal reservoir is the white-footed mouse. Babesia species, like Plasmodium, are obligate intracellular parasites of erythrocytes and may cause a malaria-like syndrome of fever and hemolysis.
Babesiosis due to Babesia microti is highly endemic in the following states: Connecticut, Massachusetts, New York, New Jersey, Rhode Island, Wisconsin, and Minnesota. Cases are also sporadically reported from many other states including Maine, Maryland, New Hampshire, and Vermont. Babesia duncani and a B. duncani-like species have been implicated in human babesiosis cases in the Pacific Northwest region of the United States. Sporadic cases have been noted in other parts of the United States. Babesia divergens occurs in Europe, and other species appear to cause sporadic disease in South America, Asia, and North Africa. Babesiosis can be transmitted via transfusion of contaminated blood products and, rarely, transplacentally.
Babesia species have a complex life cycle that includes asexual reproduction in mammalian host erythrocytes and sexual reproduction in tick vectors. The sporozoite form is injected into the skin of humans by a feeding tick. In erythrocytes, Babesia trophozoites reproduce by binary fission. Two or four merozoites are produced. If four remain close together, this merozoite tetrad form may be seen on Giemsa- or Wright-stained thin smears of blood (as the pathognomonic "Maltese cross"). The emergence of merozoites from erythrocytes causes cell lysis, and new infection of red blood cells ensues. Hemolytic anemia may develop accompanied by tissue hypoxia. Autoimmune hemolytic anemia may also occur.
Immunocompromised patients, particularly surgically or functionally asplenic individuals, are more likely to develop symptomatic disease and severe disease. Other risk factors for severe babesiosis include age greater than 50 years, cancer, human immunodeficiency virus infection, organ transplantation, hemoglobinopathy, chronic heart, lung or liver disease, and receipt of immunomodulatory agents.
The incubation period post-tick bite is 1-6 weeks but may be as long as 9 weeks in transfusion-related infection. Infections are asymptomatic or mild in most immunocompetent individuals. Most symptomatic infections are mild and self-limiting and present as a nonspecific viral-like illness characterized by gradual onset of fatigue, malaise, and fever and one or several of the following symptoms: chills, sweats, headache, myalgia, arthralgia, anorexia, cough, and nausea. There are few findings on physical exam except for fever and occasionally mild splenomegaly, hepatomegaly, or both. With the exception of petechiae and ecchymoses in severe infection, other skin manifestations are not observed.
Complications of more severe infection include acute respiratory failure, disseminated intravascular coagulation, congestive heart failure, lethargy, coma, and renal failure. Mortality rates of 6% to 9% have been reported in patients with severe infection. Most of these cases were in patients older than 50 and with significant comorbidities. Relapse of hemolytic anemia and symptoms is uncommon in treated and otherwise healthy patients, even though parasitemia may persist for over 1 year. Relapsing or persistent disease despite treatment may occur in immunosuppressed individuals.
Codes
ICD10CM: B60.0 – Babesiosis
SNOMEDCT: 21061004 – Babesiosis
Look For
Subscription Required
Diagnostic Pearls
Subscription Required
Differential Diagnosis & Pitfalls
Other Tick-Borne Illnesses:
Human ehrlichiosis and anaplasmosis – No evidence of hemolysis; Giemsa- or Wright-stained peripheral blood smear may show intracytoplasmic morulae in polymorphonucleocytes or monocytes.
Rocky Mountain spotted fever – Look for the rash, which starts peripherally, can involve palms and soles, and may become petechial in nature. Hemolysis is unlikely to occur.
Lyme disease – Look for the presence of the typical rash, erythema chronicum migrans; no hemolysis.
Borrelia miyamotoi infection – Relapsing viral-like febrile illness can occur. Meningitis has been noted in immunocompromised patients. Occurs in areas endemic for Lyme disease in the United States; other cases have been noted in Japan and Russia. No hemolysis.
Tularemia – Look for a painful maculopapular lesion at the entry site that progresses to an ulcer and associated regional tender lymphadenopathy. The "typhoidal" form of tularemia presents without skin or lymph node involvement; no evidence of hemolysis.
Non Vector-Borne Illnesses:
Infectious mononucleosis – Look for atypical lymphocytosis, prominent sore throat, and lymphadenopathy.
Falciparum malaria – Travel / exposure history is important to determine whether the patient is at risk for malaria, babesiosis, or both. Careful examination of blood smears is essential. Tetrad forms are not seen with malaria. Babesia ring forms do not display hemozoin (brown pigment deposits) seen in older ring stages of Plasmodium falciparum.
