Persistent and relapsing babesiosis in immunocompromised patients.

Background: Human babesiosis is a tickborne malaria-like illness that generally resolves without complication after administration of atovaquone and azithromycin or clindamycin and quinine. Although patients experiencing babesiosis that is unresponsive to standard antimicrobial therapy have been described, the pathogenesis, clinical course, and optimal treatment regimen of such cases remain uncertain.

Methods: We compared the immunologic status, clinical course, and treatment of 14 case patients who experienced morbidity or death after persistence of Babesia microti infection, despite repeated courses of antibabesial treatment, with those of 46 control subjects whose infection resolved after a single course of standard therapy.

Reinfection and relapse in early Lyme disease.

To determine whether recurrent episodes of appropriately treated Lyme disease are caused by reinfection or relapse, we monitored pertinent clinical manifestations and serology of residents of an endemic site each year for 14 years. Of 253 episodes of early Lyme disease recorded among 213 residents, we observed 40 recurrent episodes. Virtually all included an erythema migrans (EM) rash that appeared at body sites that differed from those of the initial rash, no subjects produced detectable levels of specific antibody between sequential episodes, all episodes occurred a year or more after the initial EM episode, and all occurred during late spring and early summer.

Increasing health burden of human babesiosis in endemic sites.

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.

Disease-specific diagnosis of coinfecting tickborne zoonoses: babesiosis, human granulocytic ehrlichiosis, and Lyme disease.

To determine whether a unique group of clinical and laboratory manifestations characterize certain major deer tick-transmitted human pathogens in North America, we compared the symptoms, short-term complications, and laboratory test results of New England residents who became ill due to > or =1 of these pathogens. Patients completed a uniformly structured questionnaire and submitted blood samples for serologic and polymerase chain reaction (PCR) testing after developing symptoms of Lyme disease, human babesiosis, or human granulocytic ehrlichiosis (HGE). Complete blood count with thin blood smear, PCR, and immunoglobulin M antibody tests helped differentiate the acute manifestations of these diseases.