Serosurvey for human babesiosis in New York

Frequency and Geographic Distribution of Borrelia miyamotoi, Borrelia burgdorferi, and Babesia microti Infections in New England Residents

BACKGROUND

Borrelia miyamotoi is a relapsing fever spirochete that relatively recently has been reported to infect humans. It causes an acute undifferentiated febrile illness that can include meningoencephalitis and relapsing fever. Like Borrelia burgdorferi, it is transmitted by Ixodes scapularis ticks in the northeastern United States and by Ixodes pacificus ticks in the western United States. Despite reports of clinical cases from North America, Europe, and Asia, the prevalence, geographic range, and pattern of expansion of human B. miyamotoi infection are uncertain. To better understand these characteristics of B. miyamotoi in relation to other tickborne infections, we carried out a cross-sectional seroprevalence study across New England that surveyed B. miyamotoi, B. burgdorferi, and Babesia microti infections.

METHODS

We measured specific antibodies against B. miyamotoi, B. burgdorferi, and B. microti among individuals living in 5 New England states in 2018.

RESULTS

Analysis of 1153 serum samples collected at 11 catchment sites showed that the average seroprevalence for B. miyamotoi was 2.8% (range, 0.6%-5.2%), which was less than that of B. burgdorferi (11.0%; range, 6.8%-15.6%) and B. microti (10.0%; range, 6.5%-13.6%). Antibody screening within county residence in New England showed varying levels of seroprevalence for these pathogens but did not reveal a vectoral geographical pattern of distribution.

CONCLUSIONS

Human infections caused by B. miyamotoi, B. burgdorferi, and B. microti are widespread with varying prevalence throughout New England.

Global meta-analysis on Babesia infections in human population: prevalence, distribution and species diversity

Human babesiosis is an emerging tick-borne protozoan zoonosis caused by parasites of the genus Babesia and transmitted by ixodid ticks. It was thought to be a public health problem mainly for the immunocompromised, however the increasing numbers of documented cases among immunocompetent individuals is a call for concern. In this systematic review and meta-analysis, we reported from 22 countries and 69 studies, an overall pooled estimate (PE) of 2.23% (95% CI: 1.46-3.39) for Babesia infections in humans. PEs for all sub-groups varied significantly (p < 0.05) with a continental range of 1.54% (95% CI: 0.89-2.65) in North America to 4.17% (95% CI: 2.11-8.06) in Europe. PEs for country income levels, methods of diagnosis, study period, sample sizes, Babesia species and targeted population ranged between 0.43% (95% CI: 0.41-0.44) and 7.41% (95% CI: 0.53-54.48). Babesia microti recorded the widest geographic distribution and was the predominant specie reported in North America while B. divergens was predominantly reported in Europe. Eight Babesia species; B. bigemina, B. bovis, B. crassa-like, B. divergens, B. duncani, B. microti, B. odocoilei and B. venatorum were reported in humans from different parts of the world with the highest prevalence in Europe, lower middle income countries and among individuals with history of tick bite and other tick-borne diseases. To control the increasing trend of this emerging public health threat, tick control in human settlements, the use of protective clothing by occupationally exposed people and the screening of transfusion blood in endemic countries are recommended.Abbreviations AJOL: African Journals OnLine, CI: Confidence interval, CIL: Country income level, df: Degree of freedom, HIC: Higher-income countries, HQ: High quality, I²: Inverse variance index, IFAT: Indirect fluorescent antibody test, ITBTBD: Individuals with tick-bite and tick-borne diseases, JBI: Joanna Briggs Institute, LIC: Lower-income countries, LMIC: Lower middle-income countries, MQ: Medium quality, NA: Not applicable, N/America: North America, OEI: Occupational exposed individuals, OR: Odds ratio, PE: Pooled estimates, PCR: Polymerase chain reaction, Prev: Prevalence, PRISMA: Preferred Reporting System for Systematic Reviews and Meta-Analyses, Q: Cochran's heterogeneity statistic, QA: Quality assessment, Q-p: Cochran's p-value, qPCR: Quantitative polymerase chain reaction, S/America: South America, Seq: Sequencing, UMIC: Upper middle-income countries, USA: United States of America.

Discovery and Surveillance of Tick-Borne Pathogens

Within the past 30 yr molecular assays have largely supplanted classical methods for detection of tick-borne agents. Enhancements provided by molecular assays, including speed, throughput, sensitivity, and specificity, have resulted in a rapid increase in the number of newly characterized tick-borne agents. The use of unbiased high throughput sequencing has enabled the prompt identification of new pathogens and the examination of tick microbiomes. These efforts have led to the identification of hundreds of new tick-borne agents in the last decade alone. However, little is currently known about the majority of these agents beyond their phylogenetic classification. Our article outlines the primary methods involved in tick-borne agent discovery and the current status of our understanding of tick-borne agent diversity.

Rise in Babesiosis Cases, Pennsylvania, USA, 2005-2018

Babesiosis is an emerging infection in the state of Pennsylvania, and clinicians need to be made aware of its clinical manifestations as well as the risk factors associated with severe disease. Before 2010, our tertiary academic center in central Pennsylvania previously saw zero cases of babesiosis. We saw our first confirmed case of Babesia infection acquired in Pennsylvania in 2011; we recorded 2 confirmed cases in 2017 and 4 confirmed cases in 2018. All 4 cases from 2018 were thought to be acquired in southcentral Pennsylvania counties, whereas prior reports of cases were predominately in the southeast and northeast counties of the state.

Transfusion transmitted babesiosis: A systematic review of reported cases

BACKGROUND

Transfusion transmitted babesiosis (TTB) has a high mortality rate but may go unrecognized, particularly in non-endemic areas. We therefore conducted a systematic review to better characterize clinical aspects of TTB.

METHODS

A literature search was conducted in PubMed and CINAHL databases, from which 25 eligible articles describing 60 TTB patients met criteria for data extraction.

RESULTS

Symptom evaluation was provided for 25 implicated donors: 18/25 (72%) were asymptomatic while 7/25 (28%) had mild flu-like symptoms but were asymptomatic at time of donation. It was common for a single donor or donation to infect multiple patients. Where reported, species included B. microti - 54/60 (90%), B. duncani - 3/60 (5%), and B. divergens-like/MO-1 - 1/60 (2%). Most TTB patients (44/60, 73%) resided in endemic states, while most TTB deaths 6/9 (67%) occurred in non-endemic states. Severity of hemolysis was proportional to degree of parasitemia. Mortality in our series was 9/60 (15%); most deaths occurred at extremes of the age spectrum: 6/9 non-survivors were aged >55 years, 2/9 were <1 year, only 1/9 was 2-54 years. Number of comorbidities was higher among non-survivors (median = 4) compared to survivors (median = 1).

CONCLUSIONS

All implicated donors (for which symptoms data were reported) resulting in TTB infections were asymptomatic at the time of donation, and it was common for a single donor or donation to infect multiple patients. Mortality of TTB appeared highest among those with more comorbidities and in non-endemic states. Heightened awareness of this diagnosis is key in its recognition.

Zoonotic Babesia: A scoping review of the global evidence

BACKGROUND

Babesiosis is a parasitic vector-borne disease of increasing public health importance. Since the first human case was reported in 1957, zoonotic species have been reported on nearly every continent. Zoonotic Babesia is vectored by Ixodes ticks and is commonly transmitted in North America by Ixodes scapularis, the tick species responsible for transmitting the pathogens that also cause Lyme disease, Powassan virus, and anaplasmosis in humans. Predicted climate change is expected to impact the spread of vectors, which is likely to affect the distribution of vector-borne diseases including human babesiosis.

METHODS

A scoping review has been executed to characterize the global evidence on zoonotic babesiosis. Articles were compiled through a comprehensive search of relevant bibliographic databases and targeted government websites. Two reviewers screened titles and abstracts for relevance and characterized full-text articles using a relevance screening and data characterization tool developed a priori.

RESULTS

This review included 1394 articles relevant to human babesiosis and/or zoonotic Babesia species. The main zoonotic species were B. microti, B. divergens, B. duncani and B. venatorum. Articles described a variety of study designs used to study babesiosis in humans and/or zoonotic Babesia species in vectors, animal hosts, and in vitro cell cultures. Topics of study included: pathogenesis (680 articles), epidemiology (480), parasite characterization (243), diagnostic test accuracy (98), mitigation (94), treatment (65), transmission (54), surveillance (29), economic analysis (7), and societal knowledge (1). No articles reported predictive models investigating the impact of climate change on Babesia species.

CONCLUSION

Knowledge gaps in the current evidence include research on the economic burden associated with babesiosis, societal knowledge studies, surveillance of Babesia species in vectors and animal hosts, and predictive models on the impact of climate change. The scoping review results describe the current knowledge and knowledge gaps on zoonotic Babesia which can be used to inform future policy and decision making.

Discovery of the Lyme Disease Agent

A detailed first-hand account of the events leading up to the discovery of the Lyme disease agent has been lacking. Nearly 40 years have elapsed since the discovery of the organism that was named Borrelia burgdorferi There are thousands of articles in the scientific and medical literature on this organism and the disease that it causes. In the interval since the organism's discovery, however, misconceptions have arisen regarding not only the disease but the discovery itself. Accordingly, with this paper, we aim to fill in the details of this episode in medical history with a joint introduction, first-person accounts by the two authors, a summary of contemporaneous events, and concluding comments. The history of the discovery of the Lyme disease agent has threads originating in different places in the United States. Studies on Long Island, NY, provided the epidemiological thread of studies on rickettsial diseases and babesiosis, linking the latter with the cutaneous manifestation of Lyme disease, now known as erythema migrans. The Long Island thread intersected Montana's Rocky Mountain Laboratories thread of studies on a relapsing fever Borrelia and its cultivation and expertise in vector biology. This intersection made possible the discovery of the spirochete and its recovery from patients. This paper stresses that what may seem to have been an individual scientific discovery is actually the product of several threads coming together and is attributable to more people than appreciated.

Polymicrobial Nature of Tick-Borne Diseases

Tick-borne diseases have doubled in the last 12 years, and their geographic distribution has spread as well. The clinical spectrum of tick-borne diseases can range from asymptomatic to fatal infections, with a disproportionate incidence in children and the elderly. In the last few years, new agents have been discovered, and genetic changes have helped in the spread of pathogens and ticks. Polymicrobial infections, mostly in Ixodes scapularis, can complicate diagnostics and augment disease severity. Amblyomma americanum ticks have expanded their range, resulting in a dynamic and complex situation, possibly fueled by climate change. To document these changes, using molecular biology strategies for pathogen detection, an assessment of 12 microbes (9 pathogens and 3 symbionts) in three species of ticks was done in Suffolk County, New York. At least one agent was detected in 63% of I. scapularis ticksBorrelia burgdorferi was the most prevalent pathogen (57% in adults; 27% in nymphs), followed by Babesia microti (14% in adults; 15% in nymphs), Anaplasma phagocytophilum (14% in adults; 2% in nymphs), Borrelia miyamotoi (3% in adults), and Powassan virus (2% in adults). Polymicrobial infections were detected in 22% of I. scapularis ticks, with coinfections of B. burgdorferi and B. microti (9%) and of B. burgdorferi and A. phagocytophilum (7%). Three Ehrlichia species were detected in 4% of A. americanum ticks. The rickettsiae constituted the largest prokaryotic biomass of all the ticks tested and included Rickettsia amblyommatis, Rickettsia buchneri, and Rickettsia montanensis The high rates of polymicrobial infection in ticks present an opportunity to study the biological interrelationships of pathogens and their vectors.IMPORTANCE Tick-borne diseases have increased in prevalence in the United States and abroad. The reasons for these increases are multifactorial, but climate change is likely to be a major factor. One of the main features of the increase is the geographic expansion of tick vectors, notably Amblyomma americanum, which has brought new pathogens to new areas. The clinical spectrum of tick-borne diseases can range from asymptomatic to fatal infections, with a disproportionate incidence in children and the elderly. In addition, new pathogens that are cotransmitted by Ixodes scapularis have been discovered and have led to difficult diagnoses and to disease severity. Of these, Borrelia burgdorferi, the agent of Lyme disease, continues to be the most frequently transmitted pathogen. However, Babesia microti, Borrelia miyamotoi (another spirochete), Anaplasma phagocytophilum, and Powassan virus are frequent cotransmitted agents. Polymicrobial infection has important consequences for the diagnosis and management of tick-borne diseases.

A prospective evaluation of chronic Babesia microti infection in seroreactive blood donors

BACKGROUND

Babesia microti is the foremost infectious risk to the US blood supply for which a Food and Drug Administration (FDA)-licensed test is unavailable for donation screening. Characterization of the antibody response to B. microti and correlation with parasitemia is necessary to guide screening and donor management policies.

STUDY DESIGN AND METHODS

During an FDA licensure trial, blood donors were prospectively screened (July-November 2013) using a B. microti-specific antibody enzyme immunoassay (EIA, Immunetics) in highly endemic (New York [NY]; n = 13,688), moderately endemic (Minnesota [MN]; n = 4583), and nonendemic (New Mexico [NM]; n = 8451) regions. Blood donors with repeat-reactive (RR) results participated in a 12-month prospective cohort study using B. microti EIA, immunofluorescent assay, polymerase chain reaction (PCR), blood smear, and clinical questionnaire.

RESULTS

Thirty-seven (61.67%; 24 NY, seven MN, six NM) of 60 eligible RR donors enrolled in the study; 20 of 37 (54%) completed the 12-month follow-up visit of which 15 (75%) were still seroreactive. Nine PCR-positive donors were identified during index screening; five participated in the follow-up study, three were PCR positive at 6 months, and two remained positive at final follow-up (378 and 404 days). Most RR donors displayed low-level seroreactivity that was either stable or waning during follow-up. The level and pattern of reactivity correlated poorly with PCR positivity.

CONCLUSION

The findings indicate prolonged seropositivity in blood donors. Although rare, asymptomatic, persistent PCR positivity supports the current policy of indefinite deferral for donors with a history of babesiosis or positive test results. Repeat testing by PCR and serology will be necessary if reinstatement is to be considered.

Human Babesiosis: Pathogens, Prevalence, Diagnosis and Treatment

Human babesiosis is a zoonotic disease caused by protozoan parasites of the Babesia genus, primarily in the Northeastern and Midwest United States due to B. microti, and Western Europe due to B. divergens. Parasites are transmitted by the bite of the ixodid tick when the vector takes a blood meal from the vertebrate host, and the economic importance of bovine babesiosis is well understood. The pathology of human disease is a direct result of the parasite's ability to invade host's red blood cells. The current understanding of human babesiosis epidemiology is that many infections remain asymptomatic, especially in younger or immune competent individuals, and the burden of severe pathology resides within older or immunocompromised individuals. However, transfusion-transmitted babesiosis is an emerging threat to public health as asymptomatic carriers donate blood and there are as yet no licensed or regulated tests to screen blood products for this pathogen. Reports of tick-borne cases within new geographical regions such as the Pacific Northwest of the US, through Eastern Europe, and into China are also on the rise. Further, new Babesia spp. have been identified globally as agents of severe human babesiosis, suggesting that the epidemiology of this disease is rapidly changing, and it is clear that human babesiosis is a serious public health concern that requires close monitoring and effective intervention measure.

Multiplex assay detection of immunoglobulin G antibodies that recognize Babesia microti antigens

Human babesiosis, a blood-borne infection caused by several species of Babesia, including B. microti, is an emerging disease that is endemic in the Northeast, upper Midwest, and Pacific Northwest regions of the United States. Risk factors for babesiosis include exposure to the infected tick vector and blood transfusions from infected donors. In this work, we cloned and expressed two of the immunodominant antigens from B. microti and used them in a multiplex bead format assay (MBA) to detect parasite-specific IgG responses in human sera. The MBA using recombinant B. microti secreted antigen 1 (BmSA1) protein was more specific (100%) and slightly more sensitive (98.7%) than the assay using a truncated recombinant BMN1-17 construct (97.6% and 97.4%, respectively). Although some antibody reactivity was observed among sera from confirmed-malaria patients, only one Plasmodium falciparum sample was simultaneously positive for IgG antibodies to both antigens. Neither antigen reacted with sera from babesiosis patients who were infected with Babesia species other than B. microti. Both positive and negative MBA results were reproducible between assays and between instruments. Additional studies of these recombinant antigens and of the multiplex bead assay using blood samples from clinically defined babesiosis patients and from blood donors are needed to more clearly define their usefulness as a blood screening assay.

Transfusion-transmitted Babesia spp.: bull's-eye on Babesia microti

Babesia spp. are intraerythrocytic protozoan parasites of animals and humans that cause babesiosis, a zoonotic disease transmitted primarily by tick vectors. Although a variety of species or types of Babesia have been described in the literature as causing infection in humans, the rodent parasite Babesia microti has emerged as the focal point of human disease, especially in the United States. Not only has B. microti become established as a public health concern, this agent is increasingly being transmitted by blood transfusion: estimates suggest that between 70 and 100 cases of transfusion-transmitted Babesia (TTB) have occurred over the last 30 years. A recent upsurge in TTB cases attributable to B. microti, coupled with at least 12 fatalities in transfusion recipients diagnosed with babesiosis, has elevated TTB to a key policy issue in transfusion medicine. Despite clarity on a need to mitigate transmission risk, few options are currently available to prevent the transmission of B. microti by blood transfusion. Future mitigation efforts may stress serological screening of blood donors in regionalized areas of endemicity, with adjunct nucleic acid testing during the summer months, when acute infections are prevalent. However, several hurdles remain, including the absence of a licensed blood screening assay and a thorough cost-benefit analysis of proposed interventions. Despite current obstacles, continued discussion of TTB without proactive intervention is no longer a viable alternative.

Zoonotic babesiosis: overview of the disease and novel aspects of pathogen identity

Babesiosis is a zoonosis caused by tick-transmitted intraerythrocytic protozoa of the Phylum Apicomplexa. The disease mostly occurs in the USA, but cases have also been reported in several European countries, in Egypt, India, Japan, Korea, Taiwan, and South Africa. The main pathological event is lysis of erythrocytes resulting in haemolytic anaemia, which in severe cases may lead to organ failure and death, particularly in immunocompromised patients. The 2 groups of parasites involved, Babesia microti-like and Babesia sensu stricto (s.s.) species, differ in their life cycle characteristics and susceptibility to antibabesial drugs. Molecular taxonomy is now making a major contribution to the identification of novel pathogens within both groups. Effective treatment of severe cases was initially hampered by the lack of specific antibabesial drugs for human use, but increased use of supportive measures and of the recently developed antimalarial, atovaquone, particularly in combination with azithromycin, has improved the prospects for management of acute disease especially when caused by Babesia s.s. species. Prevention should be based primarily on increasing the awareness of physicians and the public to the risks, but infection from blood transfusions is particularly difficult to prevent. Expanding deer populations, resulting in wider distribution and greater abundance of ticks, heightened medical awareness, and growing numbers of immunocompromised patients are likely to result in a continuing rise of reported cases.

Human babesiosis

Human babesiosis is an emerging intraerythrocytic infection caused by protozoal parasites transmitted by ixodid ticks. Babesiosis is endemic in the northeastern and upper midwestern regions of the United States and is found sporadically in other parts of the United States, Europe, Asia, Africa, and South America. Babesial infections range from asymptomatic to severe and occasionally are fatal. Specific laboratory diagnosis of babesial infection is made by morphologic examination of Giemsa-stained blood smears, serology, and amplification of babesial DNA using polymerase chain reaction. The combination of atovaquone and azithromycin is the treatment of choice for mild-to-moderate illness, whereas clindamycin and quinine and exchange transfusion are indicated for severe disease.

Retrospective seroepidemiological survey for human babesiosis in an area in Japan where a tick-borne disease is endemic

A total of 1,335 archived human sera collected in 1985 from an area in Japan where a tick-borne disease is endemic were examined by indirect immunofluorescence antibody test (IFAT) to estimate seroprevalence against three serologically distinct types of Babesia microti-like parasites; namely, Hobetsu, Kobe, and U.S. types. Eighteen sera (1.3%) were found to be IFAT-positive (titer 1:100-1:6,400), of which 14 and three were ascertained by Western blot analysis to be positive against the Hobetsu and Kobe types, respectively. In addition, four sera showed an IFAT titer of 1:100 against the U.S. type, but they appeared to be false-positive because they were cross-reactive against the Hobetsu and Kobe types, and also because a U.S.-type parasite has not been found in Japan. Our results suggest that human babesiosis in Japan occurred prior to the discovery of the index case in 1999 and that the infections were caused mainly by Hobetsu-type parasites.

Transfusion-associated babesiosis after heart transplant

We describe a 54-year-old spleen-intact man with transfusion-associated Babesia microti infection after a heart transplant. Adult respiratory distress syndrome developed in the patient, and he required mechanical ventilation. Our experiences with this patient suggest that babesiosis should be considered in the differential diagnosis of transplant patients who have fever and hemolytic anemia.

Coexposure to Borrelia burgdorferi and Babesia microti does not worsen the long-term outcome of lyme disease

Previous studies suggest that concurrent Lyme disease and babesiosis produce a more sever illness than either disease alone. The majority of babesiosis infections, however, are subclinical. Our objective was to characterize on the basis of a total-population survey of Nantucket Island, Massachusetts, whether coexposure to Lyme disease and babesiosis causes more severe illness or poorer long-term outcomes than Lyme disease alone. In this retrospective cohort study, residents indicating a history of Lyme disease were compared with randomly selected population controls on a standardized medical history, blinded physical examination, and serological studies for Borrelia burgdorferi and Babesia microti. Serological evidence of exposure to babesiosis was not associated with increased severity of acute Lyme disease. The groups did not differ with regard to the prevalence of constitutional, musculoskeletal, or neurological symptoms a mean of 6 years after acute Lyme disease. Prior Lyme disease and serological exposure to B. microti are not associated with poorer long-term outcomes or more persistent symptoms Lyme disease alone.

Babesiosis

Babesiosis is an emerging, tick-transmitted, zoonotic disease caused by hematotropic parasites of the genus Babesia. Babesial parasites (and those of the closely related genus Theileria) are some of the most ubiquitous and widespread blood parasites in the world, second only to the trypanosomes, and consequently have considerable worldwide economic, medical, and veterinary impact. The parasites are intraerythrocytic and are commonly called piroplasms due to the pear-shaped forms found within infected red blood cells. The piroplasms are transmitted by ixodid ticks and are capable of infecting a wide variety of vertebrate hosts which are competent in maintaining the transmission cycle. Studies involving animal hosts other than humans have contributed significantly to our understanding of the disease process, including possible pathogenic mechanisms of the parasite and immunological responses of the host. To date, there are several species of Babesia that can infect humans, Babesia microti being the most prevalent. Infections with Babesia species generally follow regional distributions; cases in the United States are caused primarily by B. microti, whereas cases in Europe are usually caused by Babesia divergens. The spectrum of disease manifestation is broad, ranging from a silent infection to a fulminant, malaria-like disease, resulting in severe hemolysis and occasionally in death. Recent advances have resulted in the development of several diagnostic tests which have increased the level of sensitivity in detection, thereby facilitating diagnosis, expediting appropriate patient management, and resulting in a more accurate epidemiological description.

Babesiosis

Babesiosis is an emerging, tick-transmitted, zoonotic disease caused by hematotropic parasites of the genus Babesia. Babesial parasites (and those of the closely related genus Theileria) are some of the most ubiquitous and widespread blood parasites in the world, second only to the trypanosomes, and consequently have considerable worldwide economic, medical, and veterinary impact. The parasites are intraerythrocytic and are commonly called piroplasms due to the pear-shaped forms found within infected red blood cells. The piroplasms are transmitted by ixodid ticks and are capable of infecting a wide variety of vertebrate hosts which are competent in maintaining the transmission cycle. Studies involving animal hosts other than humans have contributed significantly to our understanding of the disease process, including possible pathogenic mechanisms of the parasite and immunological responses of the host. To date, there are several species of Babesia that can infect humans, Babesia microti being the most prevalent. Infections with Babesia species generally follow regional distributions; cases in the United States are caused primarily by B. microti, whereas cases in Europe are usually caused by Babesia divergens. The spectrum of disease manifestation is broad, ranging from a silent infection to a fulminant, malaria-like disease, resulting in severe hemolysis and occasionally in death. Recent advances have resulted in the development of several diagnostic tests which have increased the level of sensitivity in detection, thereby facilitating diagnosis, expediting appropriate patient management, and resulting in a more accurate epidemiological description.

Transfusion-associated transmission of babesiosis in New York State

BACKGROUND

Babesiosis can be life-threatening in immunocompromised individuals. Although the disease is usually transmitted by tick bite, more than 20 cases have been reported of infection transmitted by transfusion of blood or blood components obtained from apparently healthy donors from endemic areas in the United States. This report describes several recent cases of transfusion-transmitted babesiosis in New York State.

STUDY DESIGN AND METHODS

Transfusion-associated incidents of babesiosis infection were identified and investigated. Seroprevalence of babesiosis in healthy blood donors in a highly endemic area was ascertained.

RESULTS

In three incidents, babesiosis was diagnosed in five of eight patients given infected blood: two premature infants, an elderly patient with gastrointestinal bleeding, and two patients with thalassemia. Seroprevalence in blood donors on Shelter Island (Suffolk County, eastern Long Island), a highly endemic area, was 4.3 percent in May 1998.

CONCLUSIONS

Infected donors lived in endemic areas and were asymptomatic with no history of tick bite. Blood collected in January 1997 from one donor was infectious. Those transfusion recipients who were infected were neonatal, elderly, or chronically transfused patients. Babesiosis should be included in the differential diagnosis of febrile illness in immunocompromised recipients of blood transfusion, particularly in the Northeastern United States.

Seroprevalence and seroconversion for tick-borne diseases in a high-risk population in the northeast United States

PURPOSE

To determine the prevalence of serologic reactivity, the 1-year incidence of seroconversion, and the frequency of multiple infections, and their associations with symptoms in a group of volunteers at high risk for tick-borne infections in New York state.

METHODS

We performed a seroepidemiologic study of Lyme borreliosis, 2 of the ehrlichioses, Rocky Mountain spotted fever, and babesiosis among 671 participants who lived or worked in a high-risk area (mainly in eastern Long Island, New York) for tick-borne diseases. Sera were collected in the winters of 1994 and 1995. Signs and symptoms of tick-borne disease were monitored monthly by mail and telephone. Lyme borreliosis serologies were done by enzyme-linked immunosorbent assay and Western blot. Rocky Mountain spotted fever serologies were initially screened using Dip-S-Ticks, followed by specific indirect immunofluorescence. Ehrlichiosis serologies were determined by epifluorescent microscopy, as were antibodies to Babesia microti.

RESULTS

Of the 671 participants, 88 (13%) had antibodies to > or = 1 tick-borne organisms, including 34 (5% of the total) with antibodies to Borrelia burgdorferi. Twenty-seven participants had evidence of exposure to B. burgdorferi at baseline. Seven participants (1%) seroconverted during the course of the study, 5 of whom were symptomatic for Lyme borreliosis. Antibodies to spotted fever group rickettsiae were seen in 28 participants (4%), 22 of whom were positive at baseline and 6 of whom seroconverted during the observation period. None of the seropositive patients had any symptoms or signs of infection. Twenty-four participants (3%) had serologic evidence of exposure to Ehrlichia (all but one to Ehrlichia equi); 5 (0.7%) seroconverted during the observation period, including 3 subjects who were asymptomatic. Antibodies to B. microti were seen in 7 participants (1%), including one asymptomatic seroconversion during the year of observation. There was evidence of possible dual infection in 5 patients.

CONCLUSION

In a high-risk population, there was evidence of exposure to 5 tick-borne pathogens; however, many infections were asymptomatic, and coinfections were rare.

Human babesiosis in Taiwan: asymptomatic infection with a Babesia microti-like organism in a Taiwanese woman

An asymptomatic Babesia infection was confirmed by laboratory diagnoses. The intraerythrocytic protozoan (designed TW1) isolated from a 51-year-old Taiwanese woman appeared to be morphologically consistent with small-form piroplasm, and measurements indicated that it had a body size of 1.5 to 2.5 microm in diameter. The typical features of ring, binary, and tetrad forms were observed in Giemsa-stained thin blood smears. A persistent and low-grade parasitemia was established after hamster inoculation. Indirect immunofluorescent-antibody reactivities indicate that this strain (TW1) of Babesia was serologically related to, but not identical to, the Babesia species (B. microti) that infects rodents. Antibody titers in the patient's sera combined with the clinical symptoms suggested that the present case was a chronic and subclinical babesial infection. A neighborhood human serologic survey indicated that the infection may have been acquired accidentally from an infected rodent and localized within the same family. Indeed, rodents from areas around the neighborhood were trapped, and a high prevalence (83%) of babesial infection was observed. The possible vector responsible for the transmission remains to be identified.

Immunoserologic evidence of coinfection with Borrelia burgdorferi, Babesia microti, and human granulocytic Ehrlichia species in residents of Wisconsin and Minnesota

In Wisconsin and Minnesota, Ixodes scapularis (Ixodes dammini) ticks are the vector of three microorganisms that may cause significant disease in humans and lower mammals. These diseases include Lyme borreliosis, which is caused by Borrelia burgdorferi, babesiosis, which is caused by Babesia microti, and human granulocytic ehrlichiosis (HGE), which is caused by an apparently new species in the genus Ehrlichia. Immunoserologic testing was performed on sera from patients with a diagnosis of one of these diseases to determine if there was evidence of coinfection with one or more of the other agents. Of 96 patients with Lyme borreliosis, 9 (9.4%) demonstrated immunoserologic evidence of coinfection: 5 (5.2%) with the agent of HGE, 2 (2.1%) with B. microti, and 2 (2.1%) with both microorganisms. Of 19 patients diagnosed with HGE, 3 (15.8%) showed immunoserologic evidence of coinfection: 1 (5.3%) with B. burgdorferi, 1 (5.3%) with B. microti, and 1 (5.3%) with both microorganisms. One patient diagnosed with babesiosis was also seropositive for ehrlichiosis. These results provide evidence for coinfection, perhaps explaining the variable manifestations and clinical responses noted in some patients with tick-transmitted diseases. In certain clinical settings, laboratory testing for coinfection is indicated to ensure that appropriate antimicrobial treatment is given.

Human babesiosis

OBJECTIVE

To describe a case of human babesiosis and review the literature on the disease.

MATERIAL AND METHODS

We describe a 62-year-old man with babesiosis, outline his clinical course and response to therapy, and discuss the use of the polymerase chain reaction for the diagnosis and monitoring of the infection.

RESULTS

The onset of the disease was insidious, with fatigue, fever, weight loss, intermittently discolored urine, and anemia. Computed tomography of the abdomen revealed a small, shrunken spleen with an irregular border. With treatment, the symptoms gradually resolved. Although peripheral blood smears were negative soon after therapy, Babesia microti DNA was detected by polymerase chain reaction 53 days after initial examination.

CONCLUSION

The development of improved methods for diagnosis, including indirect immunofluorescent antibody assays and the polymerase chain reaction, provides more sensitive detection of the parasitemia associated with babesiosis. Use of these methods may help to delineate the complete clinical spectrum of this infection and its geographic distribution in the United States.

Detection of Babesia microti by polymerase chain reaction

Human babesiosis, which is caused by infection with the intraerythrocytic malarialike protozoan Babesia microti, has recently been diagnosed with increasing frequency in residents of New England. Diagnosis is difficult because of the small size of the parasite and the sparse parasitemia that is characteristic of most infections with this pathogen. We generated B. microti-specific DNA sequence information by universal primer amplification of a portion of the eukaryotic 16S-like gene; this was followed by direct DNA sequence analysis. Specific primers were synthesized on the basis of this sequence information for use in the polymerase chain reaction (PCR). The PCR-based system demonstrates a strong bias for detection of B. microti as opposed to Babesia gibsoni and does not amplify vertebrate DNA. The analytical sensitivity of the system is approximately three merozoites. Blood specimens from 12 patients with clinically diagnosed and parasitologically confirmed babesiosis from Nantucket Island, Mass., were PCR positive in a blinded test of this procedure. Thus, DNA amplification may provide an adjunct to conventional methods for the diagnosis of human babesiosis and may provide a new means of monitoring therapy or enhancing epidemiological surveillance for this emerging pathogen.

Ribosomal DNA probe for differentiation of Babesia microti and B. gibsoni isolates

The objective of this study was to determine whether different isolates of Babesia microti could be distinguished from morphologically similar isolates of B. gibsoni by using a ribosomal DNA (rDNA) probe. A Babesia-specific rDNA probe was obtained by polymerase chain reaction amplification of sequences from B. microti DNA using universal primers directed against highly conserved portions of the eukaryotic 16S-like rRNA gene. The chemiluminescent rDNA probe hybridized to Southern blots of restriction endonuclease-digested DNA preparations of different isolates of B. gibsoni from infected dogs and B. microti from infected humans and white-footed mice. Restriction fragment length polymorphisms served to differentiate these species. Although the hybridization patterns seen with DNAs from six B. microti isolates did not vary, those of the five B. gibsoni isolates did indicate genotypic variation. We concluded that isolates of B. microti and B. gibsoni can be differentiated on the basis of restriction fragment length polymorphism detected with a chemiluminescent rDNA probe.

Geographical and temporal distribution of babesial infection in Connecticut

Human babesiosis was first recognized in Connecticut in 1989, nearly 15 years after Lyme disease, a similarly transmitted spirochetosis, was detected in the state. To determine the seroprevalence for the babesial pathogen and whether it was recently introduced, we used an indirect immunofluorescence assay to test for Babesia microti antibody in 1,285 Connecticut residents. Four groups were studied: I, people seropositive for Lyme disease, tested from 1986 to 1989; II, randomly selected outpatients tested in 1989; III, college students residing in Connecticut, tested from 1959 to 1989; and IV, healthy people without tick exposure or Lyme disease, tested in 1989. Babesia seropositivity was significantly higher in group I (9.5%; n = 735) than in groups II (2.6%; n = 304, P less than 0.0001) and III (1.0%; n = 206, P less than 0.0001) but not group IV (2.5%, n = 40). Babesia seropositivity for group I ranged from 9.2 to 10.2% between 1986 and 1989, and Babesia seropositivity for group III ranged from 0% between 1959 and 1985 to 2.9% between 1986 and 1989. There is a considerable risk of babesial infection among residents of the Connecticut mainland who are seropositive for Lyme disease, a risk that appears to have remained constant over the past 5 years.

Increase in micronucleated erythrocytes associated with babesiosis in Syrian golden hamsters

The effect of infection by Babesia microti, a tick-borne piroplasm endemic to the northeastern United States, on the temporal pattern of micronucleated erythrocyte frequencies in peripheral blood was investigated in male Syrian golden hamsters. Significantly greater frequencies of micronucleated erythrocytes occurred in the blood of infected hamsters from 26 to 46 days after injection with B. microti, the magnitude of which within individual hamsters correlated highly with the percentage of polychromatic erythrocytes and the extent of parasitization. These data suggest that parasitic infection and other factors which alter the rate of erythropoiesis should be considered when the micronucleus assay is used in environmental or laboratory studies of genetic toxicity.

The impact of cultural and environmental changes on the epidemiology and control of human babesiosis

The infection of humans with Babesia spp. has provided a well studied example of how cultural and environmental factors have contributed to the spread of an infection. Individuals developing babesiosis have been those engaging in life styles which put them at risk of tick bites. Farmers, hunters and other outdoor types are most frequently infected. The forms of human babesiosis which occur in the north-eastern United States are directly related to the spread of deer and the deer tick, which is the vector of the Babesia responsible for human infection. The spread of deer in the region was a direct result of cultural changes resulting in altered human behaviour which permitted deer to exist close to human settlement areas.