What is Babesiosis?
Babesiosis is an infectious disease caused by parasites which invade and burst red blood cells open. In the United States, particularly along the northeastern seaboard, babesiosis is caused by Babesia microti. This parasite is common among white-footed mice, and is transmitted from one mouse to another by the deer tick. Unfortunately, deer ticks feed on people, thereby transmitting the parasite. Unlike Lyme disease, its fellow traveler, babesiosis can be life-threatening. The infection can also be acquired through transfusion of blood products, particularly red blood cells.
The Rise of Babesiosis
The first case of babesiosis caused by Babesia microti occurred in 1969 in a patient who had vacationed on Nantucket, an island off the coast of Massachusetts. Babesiosis was soon reported from other islands in the region, including Martha’s Vineyard, Block Island, Shelter Island, eastern Long Island, and Fire Island. Nowadays, babesiosis is diagnosed from Cape Cod to Connecticut and from the Lower Hudson Valley to Maryland. Cases are also reported from the upper Midwest. Once a rare disease, babesiosis has become a serious public health issue.
The State of New York was the first to institute mandatory reporting for babesiosis. In this state, the number of cases reported each year began to increase in the late 90’s (see graph). Over the last decade, the number of cases reported each year increased by five fold. Similar trends have been observed throughout New England.
The recent emergence of babesiosis has been attributed to a cascade of environmental changes. Owing to the lack of natural predators and the public outcry over hunting, deer herds have become larger. Because ticks feed on deer, tick populations have thrived. As winters have become milder, ticks have survived in greater numbers. Culling deer herds was proposed, but this measure has been difficult to implement. Tick repellents are available, but their use has been insufficient to prevent the rise of human babesiosis.
Individuals at Risk
In young and otherwise healthy individuals, infection with Babesia microti typically is asymptomatic or causes a mild illness. Fever is the main symptom, preceded by a gradual onset of fatigue and malaise. Fever often is accompanied by chills, muscle pain, sweats and nausea. In most mild cases, symptoms resolve spontaneously or are successfully treated with a single course of antibiotics.
In older adults and the immunocompromised, however, babesiosis can be severe despite standard antimicrobial therapy. Severe babesiosis often requires hospitalization. Among hospitalized individuals, about half develop at least one complication, and up to a tenth die.
Most cases of babesiosis develop following the bite of an infected tick, but cases acquired through transfusion of blood products are on the rise. Short of a systematic screening of the blood supply, transfusion transmitted babesiosis occurs because some blood donors are unaware that they are infected with Babesia microti.
Dr. Edouard Vannier, an Assistant Professor at Tufts Medical Center, collaborates with leading scientists and expert clinicians in Boston and elsewhere in New England to:
- Identify the mechanisms by which people are or become susceptible to babesiosis
- Develop novel therapeutic agents that help prevent or reverse severe babesiosis
The thrust of the research takes advantage of two common lines of laboratory mice. In one line, the parasite load is higher as the age at infection increases. In the other, the parasite load is marginal, even in old age. Capitalizing on a genetic approach initiated years ago to elucidate the basis of age-acquired susceptibility to babesiosis, Dr. Vannier’s laboratory is actively pursuing:
- A novel gene of red blood cells as a factor of susceptibility to babesiosis
- A poorly characterized immune gene as a factor of resistance to babesiosis
- A chromosomal region that confers susceptibility in old, but not in young age
A second approach relies on the analysis of DNA obtained from patients who experienced mild or severe babesiosis and from individuals who were infected with Babesia microti but did not have symptoms. The goals are to build a large bank of DNA samples and to identify genetic variations that are associated with disease susceptibility or severity, particularly in the elderly.
Our goal is to develop a comprehensive understanding of the factors that render some individuals highly susceptible to babesiosis. Because aging is a risk factor for severe babesiosis, we expect to identify some of the fundamental changes that occur during the aging process and that render the elderly susceptible to infection.
Current therapies for babesiosis target Babesia microti itself (using antibiotics) or parasitized red blood cells (using exchange transfusion). To enrich the therapeutic arsenal against this disease, we will seek to develop novel compounds/drugs that prevent the invasion of red blood cells by the parasite or increase the strength of the immune response against this parasite.
Other projects will seek to optimize the use and the modalities of exchange transfusion in the treatment of severe babesiosis.
Edouard G. Vannier, PharmD, PhD
Assistant Professor, Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center
Assistant Professor, Tufts University School of Medicine
Mark Ziggy Vrana
Junior at Tufts University, Boston, MA
Freshman at University of Chicago, IL
June 4, 2014 – Dr. Vannier, in collaboration with Dr. Athar Chishti, Professor at Tufts University School of Medicine, is granted a Tufts Collaborates! Award for the project entitled “Host-Parasite Interactions in Babesiosis”. The goal of the research is to elucidate Babesia microti proteins that are involved in the attachment of Babesia parasites to human red blood cells.
June 4, 2014 – Dr. Vannier, in collaboration with Dr. John Leong, Chief of Molecular Biology and Microbiology at Tufts University School of Medicine and Dr. Arlin Rogers, Associate Professor at the Tufts Cummings School of Veterinary Medicine, is granted a Tufts Collaborates! Award for the project entitled “A Novel Genetic Determinant of Susceptibility to Colonic Inflammation”. The proposed research will use the Citrobacter rodentium mouse model to determine whether a novel determinant of susceptibility to babesiosis confers susceptibility to colonic inflammation.
April 23, 2014 – Dr. Vannier is granted funds by the National Research Center for Protozoan Diseases (NRCPD) and Obihiro University of Agriculture and Veterinary Medicine (OUAVM) for the research project entitled “Identification of Novel Therapeutics for Babesiosis”. This project will be carried out in collaboration with Pr. Ikuo Igarashi (NRCPD and OUAVM).
December 9, 2013 – Dr. Vannier gives a lecture entitled “Determinants of Host Resistance to Babesiosis, an Emerging Infectious Disease” at the National Research Center for Protozoan Diseases in Obihiro, Hokkaido, Japan.
August 19, 2013 – Dr. Vannier presents his research on the “Immune Basis for Resolution of Babesia microti Infection in Immunosuppressed Hosts” at the 13th International Conference of Lyme Borreliosis and Other Tick-Borne Diseases in Boston, MA.
August 15, 2013 – Dr. Vannier gives a presentation entitled “Cytokines in Host Resistance to Babesiosis, an Emerging Infectious Disease” at the Special Symposium organized by the Interleukin Foundation at the University of Colorado in Denver, CO.
Read the Press Release by the National Research Fund for Tick-Borne Diseases on February 15, 2013. Dr. Vannier receives one of their four awards in support of his groundbreaking research on the genetic variations that predispose people to severe babesiosis.
Read the New York Times article entitled Another Tick-Borne Disease to Guard Against published on July 30, 2012. This article highlights the importance of babesiosis research and Dr. Vannier's role in shaping how this research is being conducted.
In the current climate of financial uncertainty, research is at the mercy of a severe shortage in federal funding. The research described above bears the promise of great scientific advances, but requires long-term investment. Your contribution can help maintain a strong research program in babesiosis.
At Tufts Medical Center, we created the "Babesiosis Research Fund”. This 501(c)(3) fund exclusively supports Dr. Vannier’s research. Your gift will be fully tax deductible as allowed by law. To donate, please visit
our Tufts Medical Center Trust website, click on “Give Now” (orange box at bottom in right column), type the amount of donation, select "Other" from the Gift Designation dropdown menu, and type "Babesiosis Research Fund" in the field beneath.
You can also donate by calling 617-636-7656 or mailing a check to Tufts Medical Center Trust, 800 Washington Street #231, Boston, MA 02111. Please make your check payable to Tufts Medical Center Trust, and indicate that you are donating to the Babesiosis Research Fund.
Thank you for your interest and generosity.