Increasing Health Burden of Human Babesiosis in Endemic Sites

Abstract

Human infection due to Babesia microti has been regarded as infrequent and a condition primarily affecting the elderly or immunocompromised. To determine whether risk in endemic sites may be increasing relative to that of Borrelia burgdorferi and to define its age-related clinical spectrum, we carried out a 10-year community-based serosurvey and case finding study on Block Island, Rhode Island. Less intensive observations were conducted in nearby sites. Incidence of babesial infection on Block Island increased during the early 1990s, reaching a level about three-fourths that of borrelial infection. The sera of approximately one-tenth of Block Island residents reacted against babesial antigen, a seroprevalence similar to those on Prudence Island and in southeastern Connecticut. Although the number and duration of babesial symptoms in people older than 50 years of age approximated those in people 20 to 49 years of age, more older adults were admitted to hospital than younger adults. Few Babesia-infected children were hospitalized. Babesial incidence at endemic sites in southern New England appears to have risen during the 1990s to a level approaching that due to borreliosis.

Multiplex Assay Detection of Immunoglobulin G Antibodies That Recognize Babesia microti Antigens

“…The risk of acquiring human B. microti infection is likely increasing due to increasing vector tick populations in areas of endemicity, increasing levels of recreational exposure to potentially infected ticks, and the lack of a sensitive and specific highthroughput screening assay for donated blood and blood products (14,19,25,27,32). In addition to traditional blood smear microscopy, Western blotting, ELISA, IFA, and PCR assays have been developed by various laboratories for diagnosis.…”

Importance of Nonenteric Protozoan Infections in Immunocompromised People

“…In contrast, Babesia infections may be self-limiting or subclinical in ICT patients (574). The risk of developing severe babesiosis also increases with age, with individuals over the age of 50 years being predisposed to severe symptoms (263,334,389). Other groups predisposed to a severe, potentially lethal form of babesiosis include those with HIV (198,214,592), those receiving immunosuppressive therapy (including transplant patients), those with leukocyte malignancies, and those without a spleen (226,331,333,366,389,574).…”

Macrophages Are Critical for Cross-Protective Immunity Conferred by Babesia microti against Babesia rodhaini Infection in Mice

“…Babesiosis causes huge economic losses in the livestock industry. Recently, the disease has become an important emerging zoonosis, with Babesia microti being the most important cause of human babesiosis in America, Europe, and Asia (23,26,27,35,55). Most of the human cases are either from tainted blood transfusions or from bites of infected Ixodes scapularis nymphs, which inject sporozoites into the bloodstream of the host during their feeding.…”