Babesiosis in Wisconsin: a potentially fatal disease

Babesia microti-induced fulminant sepsis in an immunocompromised host: A case report and the case-specific literature review

Babesia microti is an obligate intra-erythrocytic parasite transmitted by infected ticks. B. microti is a eukaryote much larger than prokaryotic microbes and more similar to human hosts in their biochemistry and metabolism. Moreover, Babesia spp. possess various immune evasion mechanisms leading to persistent and sometimes life-threatening diseases in immunocompromised hosts. Chronic lymphocytic leukemia (CLL) is the most prevalent adult B-cell malignancy, and a small percentage of CLL transforms into aggressive lymphomas. CLL also causes immune dysfunction due to the over-expansion of immature and ineffective B-cells. When our patient with indolent CLL presented with anemia, pancytopenia, and splenomegaly, all his healthcare providers presumptively assumed a malignant transformation of CLL. However, these are also the signs and symptoms of babesiosis. Herein, we report a case where B. microti infection was presumed as a malignant transformation of CLL and narrowly avoided a devastating outcome. Although the patient developed fulminant sepsis, he finally received the correct diagnosis and treatment. Unfortunately, the disease recrudesced twice. Each time, it became more difficult to control the infection. We describe the clinical course of the case and discuss the case-specific literature review. This report highlights the importance of differential diagnoses ruling out infections which include babesiosis, prior to initiating the treatment of B-cell malignancy.

Red Cell Exchange as Adjunctive Therapy for Babesiosis: Is it Really Effective?

Human babesiosis is a parasitic disease prevalent in the Northeastern and Midwestern United States (US). Treatment with antibiotics is the standard of care but red cell exchange (RCE) has been used as an adjunctive treatment in more severe disease. Data for the efficacy of RCE in the treatment of babesiosis has been based on case reports and case series. An English language literature search was conducted for cases of babesiosis treated with RCE since 1980 and relevant laboratory and clinical outcome data were extracted. Similar data were obtained on severe cases of babesiosis referred for RCE in our hospitals in the time period 2000 to 2020. Fifty reports including forty-one individual case reports and nine case series were retrieved. There were 108 patients that underwent RCE with an overall mortality rate of 20%. Some patients had more than one RCE. The patients varied in the level of anemia and evidence of compromise of renal or pulmonary function. The pre-RCE level of parasitemia varied between 1.7% to 85% with the vast majority >10%. The post-RCE level of parasitemia varied between 1% to 10%. Since 2000, 32 patients were referred for RCE in our hospitals and RCE was performed on 23 of 32. There were more patients treated with RCE in the second decade as compared to the first decade, 19 versus 4 respectively. The overall mortality was 22% similar to the national data. Comparing the cohort treated with RCE to the 9 patients who were treated only with antibiotics, there were similar levels of parasitemia and laboratory parameters. The overall number of days needed to achieve a parasite count <1% was similar between the two cohorts and mortality for the antibiotics only cohort was 0%. More than 40 years after the first reported case of RCE in severe babesiosis it cannot be concluded that this adjunctive therapy favorably influences the clinical outcome. Since there is largely equipoise, a registry of severe patients treated with or without RCE could identify a benefit or otherwise.

Babesiosis Surveillance - United States, 2011-2015

PROBLEM/CONDITION

Babesiosis is caused by parasites of the genus Babesia, which are transmitted in nature by the bite of an infected tick. Babesiosis can be life threatening, particularly for persons who are asplenic, immunocompromised, or elderly.

PERIOD COVERED

2011-2015.

DESCRIPTION OF SYSTEM

CDC has conducted surveillance for babesiosis in the United States since January 2011, when babesiosis became a nationally notifiable condition. Health departments in states in which babesiosis is reportable voluntarily notify CDC of cases through the National Notifiable Diseases Surveillance System (NNDSS) and submit supplemental case information by using a babesiosis-specific case report form (CRF). As of 2015, babesiosis was a reportable condition in 33 states compared with 22 states in 2011.

RESULTS

For the 2011-2015 surveillance period, CDC was notified of 7,612 cases of babesiosis (6,277 confirmed [82.5%] and 1,335 probable [17.5%]). Case counts varied from year to year (1,126 cases for 2011, 909 for 2012, 1,761 for 2013, 1,742 for 2014, and 2,074 for 2015). Cases were reported among residents of 27 states. However, 7,194 cases (94.5%) occurred among residents of seven states with well-documented foci of tickborne transmission (i.e., Connecticut, Massachusetts, Minnesota, New Jersey, New York, Rhode Island, and Wisconsin). Maine (152 cases) and New Hampshire (149 cases) were the only other states that reported >100 cases for the 5-year period, and both states also reported increasing numbers of cases over time. The median age of the 7,173 patients with available information was 63 years (range: <1-99 years; interquartile range: 51-73 years); 4,156 (57.9%) were aged ≥60 years, and 15 (<1%) were aged <1 year. The proportion of patients with symptom onset during June-August was >70% for each of the 5 surveillance years. Approximately half (3,004 of 6,404 [46.9%]) of the patients with available data were hospitalized at least overnight. Hospitalization rates ranged from 16.0% among patients aged 10-19 years (16 of 100) to 72.6% among those aged ≥80 years (552 of 760). Hospitalizations were reported significantly more often among patients who were asplenic than among patients who were not (106 of 126 [84.1%] versus 643 of 1,396 [46.1%]). Fifty-one cases of babesiosis among recipients of blood transfusions were classified by the reporting health department as transfusion associated. The median intervals from the earliest date associated with each case of babesiosis to the initial report via NNDSS and submission of supplemental CRF data to CDC were approximately 3 months and 1 year, respectively.

INTERPRETATION

For the first 5 years of babesiosis surveillance, the reported cases occurred most frequently during June-August in the Northeast and upper Midwest. Maine and New Hampshire reported increasing numbers of cases over time, which suggests that foci of transmission might be expanding. Hospitalizations were common, particularly among patients who were asplenic or elderly.

PUBLIC HEALTH ACTION

Persons who live in or travel to regions where babesiosis is endemic should avoid tick-infested areas, apply repellent to skin and clothing, conduct full-body inspections for ticks after being outdoors, and remove attached ticks with fine-tipped tweezers as soon as possible. Prevention measures are especially important for persons at risk for severe babesiosis. Increases in the number and geographic range of reported cases warrant investigation to identify contributory factors (e.g., changes in tick density or in testing or surveillance methods). Complete and timely submission of risk factor data could facilitate assessments of the geographic ranges and transmission routes of Babesia parasites. Efforts to allow for electronic submission of CRF data are under way at CDC; electronic submission is expected to improve the timeliness, uniformity, and completeness of the data.

Diagnosis, Treatment, and Prevention of Lyme Disease, Human Granulocytic Anaplasmosis, and Babesiosis: A Review

IMPORTANCE

Lyme disease, human granulocytic anaplasmosis (HGA), and babesiosis are emerging tick-borne infections.

OBJECTIVE

To provide an update on diagnosis, treatment, and prevention of tick-borne infections.

EVIDENCE REVIEW

Search of PubMed and Scopus for articles on diagnosis, treatment, and prevention of tick-borne infections published in English from January 2005 through December 2015.

FINDINGS

The search yielded 3550 articles for diagnosis and treatment and 752 articles for prevention. Of these articles, 361 were reviewed in depth. Evidence supports the use of US Food and Drug Administration-approved serologic tests, such as an enzyme immunoassay (EIA), followed by Western blot testing, to diagnose extracutaneous manifestations of Lyme disease. Microscopy and polymerase chain reaction assay of blood specimens are used to diagnose active HGA and babesiosis. The efficacy of oral doxycycline, amoxicillin, and cefuroxime axetil for treating Lyme disease has been established in multiple trials. Ceftriaxone is recommended when parenteral antibiotic therapy is recommended. Multiple trials have shown efficacy for a 10-day course of oral doxycycline for treatment of erythema migrans and for a 14-day course for treatment of early neurologic Lyme disease in ambulatory patients. Evidence indicates that a 10-day course of oral doxycycline is effective for HGA and that a 7- to 10-day course of azithromycin plus atovaquone is effective for mild babesiosis. Based on multiple case reports, a 7- to 10-day course of clindamycin plus quinine is often used to treat severe babesiosis. A recent study supports a minimum of 6 weeks of antibiotics for highly immunocompromised patients with babesiosis, with no parasites detected on blood smear for at least the final 2 weeks of treatment.

CONCLUSIONS AND RELEVANCE

Evidence is evolving regarding the diagnosis, treatment, and prevention of Lyme disease, HGA, and babesiosis. Recent evidence supports treating patients with erythema migrans for no longer than 10 days when doxycycline is used and prescription of a 14-day course of oral doxycycline for early neurologic Lyme disease in ambulatory patients. The duration of antimicrobial therapy for babesiosis in severely immunocompromised patients should be extended to 6 weeks or longer.

A case of human infection with a novel Babesia species in China

Background

Babesiosis is an uncommon but emerging tick-borne disease caused by the genus Babesia. In this case study, we report a case of human infection with a novel Babesia sp. in China.

Findings

The patient in question had been suffering from repetitive occurrences of mild fever of unknown origin and fatigue for 10 years. Ring forms, tetrads, and one or two dots of chromatin or trophozoite-like organisms were observed in the patient’s thin blood smears and bone marrow smears. Using a confocal laser-scanning microscope, it was observed that the patient’s serum had reactivity with the surface proteins of the B. microti strain. Electron microscopy revealed oval red blood cells with 1 ~ 2 μm of knob protrusions in the cellular membrane. The results of the Babesia-specific nested PCR assay for 18S rRNA confirmed the presence of Babesia infection. The construction of a phylogenetic relationship showed clustering with B. microti and B. duncani, which was identified as a novel Babesia species and named as Babesia sp. XXB/HangZhou. Azithromycin, doxycycline, and moxifloxacin hydrochloride were shown to relieve symptoms but were not as effective after continuous usage. After atovaquone (Mepron®) administration, the patient recovered from fever and tested negative for detection of Babesia-specific genes.

Conclusion

Babesia sp. XXB/HangZhou is a novel Babesia species, which causes mild babesiosis in an immunocompetent patient.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-016-0121-1) contains supplementary material, which is available to authorized users.

Fatal multiple deer tick-borne infections in an elderly patient with advanced liver disease

We present a case of a 66-year-old woman with decompensated alcoholic liver cirrhosis and poorly controlled non-insulin-dependent diabetes mellitus who was admitted with a 1 day history of altered mental status, high-grade fevers, worsening jaundice and generalised malaise with subsequent development of hypotension requiring intensive care. She was diagnosed with severe babesiosis with high-grade parasitaemia. She was also found to have Lyme disease coinfection. Despite aggressive therapeutic measures including appropriate antibiotics and multiple exchange blood transfusions, she developed septic shock and fulminant multiple organ failure with eventual demise. In this article, we highlight multiple tick-borne illnesses in a vulnerable host, in this case an elderly patient with liver cirrhosis, as risk factors for severe morbidity and potentially fatal outcomes.

Development of droplet digital PCR for the detection of Babesia microti and Babesia duncani

Babesia spp. are obligate protozoan parasites of red blood cells. Transmission to humans occurs through bites from infected ticks or blood transfusion. Infections with B. microti account for the majority of the reported cases of human babesiosis in the USA. A lower incidence is caused by the more recently described species B. duncani. The current gold standard for detection of Babesia is microscopic examination of blood smears. Recent PCR-based assays, including real-time PCR, have been developed for B. microti. On the other hand, molecular assays that detect and distinguish between B. microti and B. duncani infections are lacking. Closely related species of Babesia can be differentiated due to sequence variation within the internal transcribed spacer (ITS) regions of nuclear ribosomal RNAs. In the present study, we targeted the ITS regions of B. microti and B. duncani to develop sensitive and species-specific droplet digital PCR (ddPCR) assays. The assays were shown to discriminate B. microti from B. duncani and resulted in limits of detection of ~10 gene copies. Moreover, ddPCR for these species were useful in DNA extracted from blood of experimentally infected hamsters, detecting infections of low parasitemia that were negative by microscopic examination. In summary, we have developed sensitive and specific quantitative ddPCR assays for the detection of B. microti and B. duncani in blood. Our methods could be used as sensitive approaches to monitor the progression of parasitemia in rodent models of infection as well as serve as suitable molecular tests in blood screening.

Current indications for the use of clindamycin: A critical review

OBJECTIVES

To review the literature and develop evidence-based guidelines for the use of the antibiotic clindamycin.

DATA SOURCES

A search of the MEDLINE database for randomized clinical trials, cohort studies and review articles that examine the therapeutic use or potential adverse effects of clindamycin was undertaken for the years 1966 to 1996. In addition, relevant citations obtained from the references cited in the identified reviews, book chapters and antibiotic guidelines were included.

DATA EXTRACTION

Selected articles examining the indications for or adverse effects from the prophylactic or therapeutic use of clindamycin were selected. A level of evidence was assigned to the indication according to published criteria.

DATA SYNTHESIS AND CONCLUSIONS

Randomized clinical trials (level 1 evidence) support the use of clindamycin in a number of common conditions, including preoperative prophylaxis, intra-abdominal infections, recurrent group A streptococcal pharyngitis, Chlamydia trachomatis cervicitis and anaerobic lung infections. Cohort studies (level 2 evidence) support the use of clindamycin for bone and soft tissue infections. Expert opinion (level 3 evidence) supports the use of clindamycin for invasive group A streptococcal infection and the treatment of diabetic foot infections. Clindamycin's disadvantages are its high cost, the common occurrence of rash and the predisposition of patients taking clindamycin to Clostridium difficile-associated colitis. Based on cohort studies, the risk of severe diarrhea in out-patients is as low as one per 1000, but the risk of in-patients acquiring C difficile colonization may be as high as 30%.

Clinical management of canine babesiosis

OBJECTIVE

To review and summarize current information regarding epidemiology, pathogenesis, and pathophysiology leading to the various clinical syndromes associated with canine babesiosis. Diagnosis, treatment, preventative strategies, and zoonotic implications are discussed.

ETIOLOGY

Babesiosis is caused by hemoprotozoa of the genus Babesia. Numerous species of Babesia exist worldwide. An increased incidence of babesiosis is described, especially in North America. The babesial organism spends the majority of its life cycle within the erythrocyte of the definitive host, resulting in hemolysis, with or without systemic complications.

DIAGNOSIS

Definitive diagnosis depends on direct visualization of the organism on blood smear or polymerase chain reaction. A positive serologic antibody test indicates exposure with or without active infection.

THERAPY

Antiprotozoal drugs, antimicrobials, and supportive care are the mainstays of babesiosis therapy.

PROGNOSIS

Prognosis depends on the severity of disease, which in turn depends on both organism and host factors. Clinical syndromes associated with a poorer prognosis include red biliary syndrome, acute renal failure, acute respiratory distress syndrome, neurologic dysfunction, acute pancreatitis, cardiac dysfunction, and hypoglycemia.

Transfusion-transmitted babesiosis in Rhode Island

BACKGROUND

Babesiosis is caused by an intraerythrocytic protozoan transmitted by ticks. Blood transfusion is another mode of transmission.

STUDY DESIGN AND METHODS

This was a retrospective study based on babesiosis cases reported to the Rhode Island Department of Health between 1999 and 2007. Additional cases were also identified.

RESULTS

Twenty-one cases of transfusion-transmitted babesiosis (TTB) were identified from 1999 through 2007. From 2005 through 2007, the incidence approached one case per 9000 units of blood transfused. One of 21 (5%) TTB cases was diagnosed in July, in sharp contrast to 65 of 152 (43%) of the total babesiosis cases diagnosed during July in Rhode Island. Many cases were identified when a complete blood count with a differential was routinely requested and parasites were noted by laboratory technologists. Most patients with TTB had underlying conditions known to predispose to symptomatic infection.

CONCLUSION

Blood transfusion is an important mode of Babesia transmission. The current screening method of omitting donors with a history of babesiosis may be effective in preventing some, but not all, cases of TTB and current processing of blood products does not eradicate this parasite. Thus, a better screening test is needed. Alternatively, pathogen reduction technology could be utilized to prevent this mode of transmission.

Red cell exchange transfusion for babesiosis in Rhode Island

We report four cases of clinically severe tick borne babesiosis treated with chemotherapy and adjunctive red cell exchange (RCE) at two Rhode Island hospitals from 2004 to 2007. All RCE procedures were performed using a Cobe Spectra device and were well tolerated without complications. The volume of allogeneic red cells used in the exchange was determined using the algorithm in the apheresis device with the input variables of preprocedure hematocrit, weight, height, an assumed allogeneic red cell hematocrit of 55 and a desired post procedure hematocrit of 27. The preprocedure level of parasitemia varied between 2.4% and 24% and the postprocedure level of parasitemia between 0.4 and 5.5% with an average overall percent reduction in parasitemia of 74%. Retrospectively, application of a new formula to calculate red cell mass appeared to correlate better with the percent reduction in parasitemia. Previous reports of RCE in babesiosis were reviewed. The reported reduction in parasitemia varied from 50% to >90%. Although a preprocedure level of parasitemia of 10% is sometimes used as a threshold for RCE in clinically severe babesiosis, this threshold does not have a firm empirical basis. No postprocedure desired level of parasitemia is indicated nor the mass of allogeneic red cells needed to achieve such a level. We conclude that current estimates of the dose of allogeneic red cells used in RCE are probably inaccurate, advocate a new formula to estimate this dose and suggest that a 90% reduction in parasitemia should be the minimally desired target of RCE in babesiosis.

Infection and co-infection rates of Anaplasma phagocytophilum variants, Babesia spp., Borrelia burgdorferi, and the rickettsial endosymbiont in Ixodes scapularis (Acari: Ixodidae) from sites in Indiana, Maine, Pennsylvania, and Wisconsin

In total, 394 questing adult blacklegged ticks, Ixodes scapularis Say (Acari: Ixodidae), collected at four sites were analyzed by polymerase chain reaction (PCR) for five microbial species: Anaplasma phagocytophilum, Babesia microti, Babesia odocoilei, Borrelia burgdorferi, and the rickettsial I. scapularis endosymbiont. Identities of genetic variants of A. phagocytophilum were determined by sequencing a portion of the 16S DNA. In 55% of infected ticks (193/351), a single agent was detected. In 45% (158/351), two or more agents were detected; 37% harbored two agents and 8% harbored three agents. One male tick, collected from Ft. McCoy, WI, harbored all four microbial genera The highest rates of co-infection were by the Ixodes endosymbiont and B. burgdorferi (95/351). Two species of Babesia co-occurred within a single tick population in Wells National Estuarine Research Reserve, Wells, ME, whereas only B. odocoilei was found in other tick populations. Only A. phagocytophilum human anaplasmosis variant was detected in questing ticks from Tippecanoe River State Park, IN; from Wells; and Ft. McCoy, whereas a single infected tick from Presque Isle, PA, was infected by AP-Variant 1. Partially engorged ticks from deer in Tippecanoe River State Park were all infected with AP-Variant 1. Frequency of infections with each agent varied among populations. Rates and types of co-infections were not significantly different from random except for the Ixodes endosymbiont and B. burgdorferi in male ticks, which co-occurred less frequently than expected. Thus, I. scapularis hosts an array of pathogenic and symbiotic agents and potential evidence of interactions among microbial species was observed.

Detection of Anaplasma phagocytophilum and Babesia odocoilei DNA in Ixodes scapularis (Acari: Ixodidae) collected in Indiana

The blacklegged tick, Ixodes scapularis Say, first reported in Indiana in 1987, has now been detected in more than half of Indiana's counties. The first case of human granulocytic ehrlichiosis (human anaplasmosis) in Indiana was reported in 2002. We now report the detection of Anaplasma phagocytophilum and Babesia odocoilei (Emerson and Wright 1968) in I. scapularis ticks collected in northern Indiana. Using polymerase chain reaction analysis, 41 of 193 adult ticks (21.2%) collected from deer were positive for A. phagocytophylum, and 22 (11.4%) were positive for Babesia sp. Restriction fragment analysis of 12, and sequencing of another five of the amplified products identified these parasites as B. odocoilei. Five ticks (2.6%) were coinfected. Eight of 68 questing adult ticks (11.8%) were positive for A. phagocytophilum; seven (10.3%) were positive for Babesia sp. Six of the latter seven positive samples were determined to be B. odocoilei by restriction fragment analysis and sequencing of two samples. None of 39 pools of nymphs was positive for Babesia sp. Three of 15 ticks (20%) collected from a dog were positive for A. phagocytophilum and three ticks (20%) were positive for Babesia sp. One was confirmed as B. odocoilei. One tick was coinfected. This is the first report of the presence of these two agents in ticks in Indiana.

Neonatal babesiosis: case report and review of the literature

A case of transfusion-associated neonatal babesiosis is presented. Jaundice, hepatosplenomegaly, anemia and conjugated hyperbilirubinemia developed in this preterm infant. The diagnosis was eventually made by blood smear, serology and polymerase chain reaction. The patient was treated with clindamycin and quinine and made a favorable recovery. Of neonatal babesiosis reported in the literature, 9 other cases are reviewed, including 6 that were transfusion-associated, 2 congenital and 2 tick transmitted.

Detection of Babesia microti DNA in Ixodes scapularis (Acari: Ixodidae) by use of Chelex 100 resin and polymerase chain reaction

A rapid and sensitive protocol using Chelex 100 resin for DNA extraction and the polymerase chain reaction for detection of Babesia microti Franca within its vector Ixodes scapularis Say is described. The level of detection of this protocol was determined to be the approximate equivalent of one parasite.

Presence of Borrelia burgdorferi (Spirochaetales: Spirochaetaceae) in southern Kettle Moraine State Forest, Wisconsin, and characterization of strain W97F51

Lyme disease, caused by Borrelia burgdorferi Johnson, Schmidt, Hyde, Steigerwalt & Brenner; babesiosis, caused by Babesia microti Franca; and human granulocytic ehrlichiosis, caused by Anaplasma phagocytophilum Bakken & Dumler have been reported in Wisconsin, mainly in the endemic areas of the northwestern part of the state. People exposed to blacklegged ticks, Ixodes scapularis Say, from this region can potentially contract one or all of these diseases concurrently. Within the past several years, there have been cases of Lyme disease reported from southeastern Wisconsin, an area that contains deer, mice, and similar vegetation found at regions with high endemicity. However, past white-tailed deer surveys suggested no existence of I. scapularis in southeastern Wisconsin. However, in 1996, we identified questing adult I. scapularis in the southernmost part of the Southern Kettle Moraine State Forest, Walworth County. To determine whether an established population of I. scapularis exists in this region, we performed a detailed survey of the abundance of host-seeking I. scapularis adults and the presence and abundance of subadults feeding on white-footed mice, Peromyscus leucopus Rafinesque. We also tested for possible infections of B. burgdorferi, Ba. microti, and A. phagocytophilum in ticks and B. burgdorferi harbored by mice. In 1997 and 1998, a total of 249 P. leucopus mice and 118 questing adult I. scapularis ticks, in addition to 157 larvae and seven nymphs feeding on mice, were collected and their locations were recorded from the Nordic trails of the Southern Kettle Moraine State Forest. Only one P. leucopus and its attached engorged I. scapularis nymph were infected with B. burgdorferi, whereas none of the engorged larvae attached to mice were infected. However, 4.2% of questing adult I. scapularis were infected with B. burgdorferi. The abundance of questing adult I. scapularis was 1.6 ticks per hour. The prevalence of subadult ticks on mice was 27%, with a mean intensity on infested mice of 2.0. I. scapularis adults were not infected with either Ba. microti or A. phagocytophilum. A unique strain of B. burgdorferi s.l. (W97F51) was discovered, showing 33 nucleotide substitutions and one codon insertion in a 567-bp fragment of the OspB gene, compared with Borrelia bissettii (strain Ca389). The sequences of ospA, ospB, ospC,fla, and rrs genes and the rrf-rrl intergenic spacer region were compared between W97F51 and other B. burgdorferi s.l. species. Although W97F51 was most genetically related to B. bissettii, the genetic identity of W97F51 was less than that of B. bissettii conspecifics. This study documents the existence of an established population of I. scapularis and the presence of B. burgdorferi with a novel strain in southeastern Wisconsin.

Babesia divergens-like infection, Washington State

Most reported U.S. zoonotic cases of babesiosis have occurred in the Northeast and been caused by Babesia microti. In Washington State, three cases of babesiosis have been reported previously, which were caused by WA1 (for “Washington 1”)-type parasites. We investigated a case of babesiosis in Washington in an 82–year-old man whose spleen had been removed and whose parasitemia level was 41.4%. The complete 18S ribosomal RNA gene of the parasite was amplified from specimens of his whole blood by polymerase chain reaction. Phylogenetic analysis showed the parasite is most closely related, but not identical, to B. divergens (similarity score, 99.5%), a bovine parasite in Europe. By indirect fluorescent-antibody testing, his serum reacted to B. divergens but not to B. microti or WA1 antigens. This case demonstrates that babesiosis can be caused by novel parasites detectable by manual examination of blood smears but not by serologic or molecular testing for B. microti or WA1-type parasites.

Enzootic Babesia microti in Maine

Human babesiosis in the northeastern United States caused by Babesia microti (Apicomplexa: Piroplasmida) is mainly reported from coastal New England sites, where deer ticks (Ixodes dammini) are common. However, the piroplasm has been detected in microtine rodents elsewhere in association with I. angustus or other nidicolous ticks, suggesting that the agent is widely distributed but zoonotically significant only where a human-biting "bridge" vector is present. To determine whether this piroplasm may be enzootic in areas where I. dammini is absent, we surveyed small mammals collected from 2 sites in Maine, where I. angustus or I. muris is common but I. dammini is not. Of 43 chipmunks, voles, deer mice, and shrews examined, 3 (6.9, 95% confidence interval 0 to 14.5) were parasitemic, as determined by blood smear or polymerase chain reaction targeting a piroplasm-specific portion of the 18S ribosomal DNA gene. Phylogenetic analysis of the sequenced amplification products demonstrates the presence of 2 forms of B. microti. We conclude that B. microti may be enzootic in the absence of I. dammini but that human risk relates to dense infestations of this human-biting tick.

Transfusion-associated Babesia gibsoni infection in a dog

A 2.5-year-old spayed female German Shepherd Dog was referred for evaluation of progressive anemia, lethargy, and weight loss. Seventeen days earlier, the dog had received a whole blood transfusion to manage hemorrhage after ovariohysterectomy. Mild fever, splenomegaly, and thrombocytopenia were also identified. Von Willebrand disease and Babesia gibsoni infection were diagnosed. Because of the serologic cross-reactivity of B gibsoni and B canis in the immunofluorescent antibody assay for IgG antibodies against these organisms, polymerase chain reaction amplification of parasite DNA was required to identify the infecting Babesia sp. The source of the B gibsoni infection was traced to an apparently healthy American Pit Bull Terrier blood donor. Despite resolution of clinical signs in the dog of this report, a series of antiparasitic treatments failed to eliminate the B gibsoni infection. Screening of potential blood donor dogs for Babesia spp is becoming increasingly important in the United States.

Endemic babesiosis in another eastern state: New Jersey

In the United States, most reported cases of babesiosis have been caused by Babesia microti and acquired in the northeast. Although three cases of babesiosis acquired in New Jersey were recently described by others, babesiosis has not been widely known to be endemic in New Jersey. We describe a case of babesiosis acquired in New Jersey in 1999 in an otherwise healthy 53-year-old woman who developed life-threatening disease. We also provide composite data on 40 cases of babesiosis acquired from 1993 through 2001 in New Jersey. The 40 cases include the one we describe, the three cases previously described, and 36 other cases reported to public health agencies. The 40 cases were acquired in eight (38.1%) of the 21 counties in the state. Babesiosis, a potentially serious zoonosis, is endemic in New Jersey and should be considered in the differential diagnosis of patients with fever and hemolytic anemia, particularly in the spring, summer, and early fall.

Babesiosis: An Update on Epidemiology and Treatment

Babesiosis is caused by a tick-borne hemoparasite that, like malaria, can cause fever, hemolysis, and anemia. Typically self-limited, in the asplenic, immunocompromised, or elderly, disease can be severe or deadly. US cases have been primarily due to Babesia microti; WA-1, which may be related to Babesia gibsoni; and MO-1, related to Babesia divergens. European infections are usually due to B. divergens. North American cases are treated either with quinine and clindamycin or with atovaquone and azithromycin. The latter regimen appears less toxic.

Transmission of Babesia microti in Minnesota through four blood donations from the same donor over a 6-month period

BACKGROUND

Babesiosis is a tick-borne zoonosis caused by intraerythrocytic protozoa. More than 40 US cases of Babesia microti infection acquired by blood transfusion have been reported. This report describes the identification of a transfusion-associated case of babesiosis and the subsequent identification of the infected blood donor and three other infected recipients of cellular blood components from three other donations by this donor.

STUDY DESIGN AND METHODS

Serum specimens from the donors of blood that had been made into cellular components received by the index recipient and from other recipients of such components from the implicated donor were tested by the indirect fluorescent antibody (IFA) assay for antibodies to B. microti. Whole blood from IFA-positive persons was tested by PCR for B. microti DNA.

RESULTS

IFA testing of serum from 31 of 36 donors implicated a 45-year-old man (titer, 1 in 256), whose donation had been used for RBCs. He likely became infected when bitten by ticks while camping in Minnesota in June 1999 and had donated blood four times thereafter. As demonstrated by PCR, he remained parasitemic for at least 10 months. Of the five other surviving recipients of cellular blood components from the implicated donor, three recipients (one for each of the three other donations) had become infected through either RBC or platelet transfusions.

CONCLUSIONS

Babesiosis should be included in the differential diagnosis of posttransfusion febrile illness, and effective means for preventing transmission by blood transfusion are needed.

Babesiosis in humans: a treatment review

Human infections with Babesia species, in particular Babesia microti, are tick-borne illnesses that are being recognised with increased frequency. Coinfection with ehrlichiosis and Lyme disease is also being recognised as an important feature of these tick-borne illnesses. Despite the superficial resemblance of Babesia to malaria, these piroplasms do not respond to chloroquine or other similar drugs. However, the treatment of babesiosis using a clindamycin-quinine combination has been successful. Data in animal models and case-reports in humans have suggested that an atovaquone-azithromycin combination is also effective. This was confirmed in a recent prospective, open, randomised trial of clindamycin-quinine versus azithromycin-atovaquone. This paper reviews the literature on the treatment of human babesiosis and the animal models of these human pathogens.

Cultivation of Babesia and Babesia-like blood parasites: agents of an emerging zoonotic disease

Babesia and its close relatives are members of a group of organisms called piroplasms, a name which comes from their pear-shaped outlines. Long associated with blood diseases of cattle and other mammals, members of the genus Babesia have been recognized since the 1950s as infectious agents in humans. Species of this protozoan blood parasite that have routinely been isolated from mice (B. microti) or cattle (B. divergens) have also been isolated from humans. In addition to these familiar species, new isolates that resist being placed in existing taxonomic categories are the basis for rethinking their phylogenetic relationships based on sequencing data. The parasite represents a threat to the safety of the blood supply in that blood from asymptomatic humans can transmit Babesia to blood recipients. Such transmissions have occurred. The development of methods for cultivation of these organisms represents a significant opportunity to study their biology and disease potential. In addition, in vitro cultivation has provided a basis for studying immune responses of mammals to these infectious agents, with the hope of ultimately producing attenuated strains that could be used for immunizing of cattle and, perhaps, humans who live in areas of endemicity. The microaerophilous stationary phase culture technique, which uses a tissue culture medium base supplemented with appropriate serum and erythrocytes, has made it possible to obtain large numbers of parasitized erythrocytes for studying the biology of this parasite.

Septic shock due to babesiosis

We present the case of a 69-year-old man with an unremarkable past medical history and an intact spleen who developed shock and renal failure due to babesiosis. Despite hemodynamic parameters showing severe distributive shock with hyperdynamic cardiac function, the patient recovered fully after treatment with quinine sulfate and clindamycin.

Tickborne infections as a cause of nonspecific febrile illness in Wisconsin

Lyme disease, human granulocytic ehrlichiosis (HGE), and babesiosis are tickborne infections that are indigenous to Wisconsin. To assess their importance as a cause of nonspecific fever, we recruited patients with febrile illness at 10 clinics in northwestern Wisconsin from May through August of both 1997 and 1998. Eligible patients had a temperature >38.0 degrees C but no rash or other localizing source. Acute and convalescent serological tests were performed for Borrelia burgdorferi, Babesia microti, and Ehrlichia equi; polymerase chain reaction was performed to detect granulocytic Ehrlichia rDNA. Seventeen (27%) of 62 eligible patients had laboratory evidence of tickborne infection, including 7 (11%) with probable Lyme disease only, 8 (13%) with HGE only, and 2 (3%) with apparent coinfection. No patients with Babesia infection were identified. Patients with and without tickborne infection were similar with regard to age, sex, symptoms, history of tick bite, and outdoor exposure. The results suggest that tickborne infections are an important cause of nonspecific febrile illness during the tick season in northwestern Wisconsin.

Human babesiosis: an emerging tick-borne disease

Human babesiosis is an important emerging tick-borne disease. Babesia divergens, a parasite of cattle, has been implicated as the most common agent of human babesiosis in Europe, causing severe disease in splenectomized individuals. In the US, Babesia microti, a babesial parasite of small mammals, has been the cause of over 300 cases of human babesiosis since 1969, resulting in mild to severe disease, even in non-splenectomised patients. Changing ecology has contributed greatly to the increase and expansion of human babesiosis in the US. A relatively recently described babesial parasite, the WA1-type, has been shown to be the causative agent in seven human cases in the western US. This parasite is closely related to babesial parasites isolated from large wild ungulates in California. Like B. microti, WA1-type parasites cause mild to severe disease and the immunopathogenesis of these parasites is distinctly different from each other in experimental infections of hamsters and mice. A B. divergens-like parasite was also identified as the cause of a fatal human babesiosis case in Missouri. Isolated cases of human babesisosis have been described in Africa and Mexico, but the causative parasites were not well characterized. Standard diagnostic techniques for human infection, such as examination of Giemsa-stained thin blood smears and serology, have been complemented with molecular techniques, such as PCR. Current treatment for babesiosis is focused on a regimen of clindamycin and quinine, although new drugs have shown promise. Prevention of infection relies on self-monitoring for the presence of ticks and, in some locations, targeted application of pesticides to decrease tick abundance. Identification of human infection with Babesia spp. will probably increase as physicians and the public become more aware of the disease, as people live and recreate in rural tick-infested areas, and as the numbers of immunocompromised individuals increase.

Fulminant babesiosis treated with clindamycin, quinine, and whole-blood exchange transfusion

BACKGROUND

Babesiosis is an increasingly recognized parasitic infection with manifestations that range from a subclinical or mild flu-like illness to life-threatening disease. Risk factors that may be associated with a more severe clinical course include immunosuppression, splenectomy, and advanced age. The most effective chemotherapeutic regimen, clindamycin plus quinine, is sometimes ineffective in cases of severe disease.

CASE REPORT

A previously healthy, 58-year-old man was infected by Babesia microti, presumably through a tick bite. He developed fulminant disease characterized by severe hemolytic anemia, disseminated intravascular coagulation, acute renal failure, and respiratory failure. There was no history of splenectomy or immunodeficiency. He was given oral clindamycin (300 mg/4x/day) 2 days before admission. Oral quinine (650 mg/3x/day) was added upon hospitalization. There was no clinical improvement despite antibiotic therapy with clindamycin and quinine. On the second hospital day, a whole-blood exchange transfusion was performed to simultaneously lower the parasite load and replace the patient's plasma. With an automated blood cell separator, 87 percent of the patient's total blood volume was exchanged. As replacement fluid, 6.7 L of packed RBCs reconstituted with FFP (average Hct, 33%) was used. The patient's Hct increased from 26.9 percent before the exchange to 28.3 percent after the exchange. The percentage of parasitized RBCs decreased from 13.8 percent just before exchange to 4.2 percent immediately after exchange. There was rapid clinical improvement after the whole-blood exchange transfusion. The patient's subsequent clinical course was marked by a disappearance of the parasitemia and continued slow, general improvement. Therapy with clindamycin was continued for 14 days after the exchange transfusion and quinine for 17 days.

CONCLUSION

In cases of severe babesiosis, prompt institution of whole-blood exchange transfusion, in combination with appropriate antimicrobial therapy, can be life-saving.

Attempt to control ticks (Acari: Ixodidae) on deer on an isolated island using ivermectin-treated corn

We report an attempt by an offshore island community to control the vector tick of Lyme disease by providing ivermectin-treated corn to an isolated herd of free-ranging white-tailed deer, Odocoileus virginianus Zimmerman. Medicated corn was supplied in troughs within the island village and from automatic feeders at remote sites during 5 consecutive fall and spring adult tick questing seasons. Acaricide consumption was monitored by assaying its presence in fresh deer pellets and its concentration in deer sera. Its effectiveness was evaluated by recording the number of adult ticks collected from the hides of deer, the number of females becoming sufficiently engorged to oviposit, and the success of subsequent oviposition and eclosion. Entomologic risk was monitored by collecting immature ticks from hosts and adult ticks from vegetation. Estimates based on a subsequent deer reduction program indicated that up to twice as many deer had been present during the project as originally presumed. For this and other reasons related to deer behavior, target levels of serum ivermectin were achieved in a minority of deer. Nevertheless, > 90% control of female tick infestation, subsequent oviposition, and larval eclosion was obtained in those 8 of 16 sampled deer with serum ivermectin levels of > or = 15 ng/ml. In addition, the ratio of females to males, the numbers of females engorging > 10 mg body weight, and the numbers of those eventually hatching, were all significantly less among ticks from island deer in comparison with ticks from untreated deer. No consistent changes in the numbers of ticks found on immature-stage hosts or removed from vegetation were noted within 3 yr of the cessation of treatment.

Detection of enzootic babesiosis in baboons (Papio cynocephalus) and phylogenetic evidence supporting synonymy of the genera Entopolypoides and Babesia

Blood smear evaluation of two baboons (Papio cynocephalus) experiencing acute hemolytic crises following experimental stem cell transplantation revealed numerous intraerythrocytic organisms typical of the genus Babesia. Both animals had received whole-blood transfusions from two baboon donors, one of which was subsequently found to display rare trophozoites of Entopolypoides macaci. An investigation was then undertaken to determine the prevalence of hematozoa in baboons held in our primate colony and to determine the relationship, if any, between the involved species. Analysis of thick and thin blood films from 65 healthy baboons (23 originating from our breeding facility, 26 originating from an out-of-state breeding facility, and 16 imported from Africa) for hematozoa revealed rare E. macaci parasites in 31%, with respective prevalences of 39, 35, and 12%. Phylogenetic analysis of nuclear small-subunit rRNA gene sequences amplified from peripheral blood of a baboon chronically infected with E. macaci demonstrated this parasite to be most closely related to Babesia microti (97.9% sequence similarity); sera from infected animals did not react in indirect fluorescent-antibody tests with Babesia microti antigen, however, suggesting that they represent different species. These results support an emerging view that the genus Entopolypoides Mayer 1933 is synonymous with that of the genus Babesia Starcovici 1893 and that the morphological variation noted among intracellular forms is a function of alteration in host immune status. The presence of an underrecognized, but highly enzootic, Babesia sp. in baboons may result in substantial, unanticipated impact on research programs. The similarity of this parasite to the known human pathogen B. microti may also pose risks to humans undergoing xenotransplantation, mandating effective screening of donor animals.

A focus of deer tick virus transmission in the northcentral United States

We screened salivary glands from adult deer ticks collected near Spooner and Hayward, Wisconsin, to determine whether deer tick virus, a recently described flavivirus, occurs with other tickborne agents in the upper Midwest. Intraacinar inclusions suggestive of replicating virus were detected in 4 (4.6%) of 87 ticks. The virus was isolated by suckling-mouse inoculation.

Transmission of parasites by blood transfusion

A number of parasitic diseases are known, or suspected to be transmitted by blood transfusion. Of greatest concern are malaria and Chagas' disease, but babesia, leishmania and toxoplasmosis also offer risk in particular locations or circumstances. Some of these parasites may be imported into non-endemic areas as a result of population movements and in some cases, the natural range of the parasite is increasing as a result of environmental change. Recent research, particularly on Chagas disease and babesiosis will be discussed, along with measures to minimize transmission of these and other parasites via transfusion.

Tick-transmitted infectious diseases in the United States

The epidemiologic concept of tick-transmitted diseases has increased in importance with the recognition of the emerging infectious diseases, Lyme borreliosis, human monocytotropic and granulocytotropic ehrlichioses, and three different babesioses. Effective public health control of these diseases would depend upon critical knowledge of the vector biology of the ticks that transmit them. Rocky Mountain spotted fever and the human ehrlichioses are life-threatening yet treatable diseases. A major problem remains establishment of the diagnosis when treatment decisions are being made. Clinical manifestations, other than erythema migrans for Lyme borreliosis, do not provide strong diagnostic clues. Ehrlichiae or babesiae are often not detected in peripheral blood smears. Frequently there are no antibodies to these diverse agents at the time of presentation, and isolation does not yield sensitive and timely results. Polymerase chain reaction, still a research tool, promises the greatest sensitivity, specificity, and timeliness. Prevention by vaccines is not yet a reality, although OspA-based vaccines offer hope for the prevention of Lyme disease.

Evaluation of selected antiprotozoal drugs in the Babesia microti-hamster model

The presently used therapy for Babesia microti infections, a combination of quinine and clindamycin, does not always result in parasitologic cures. To identify possible alternative chemotherapeutic agents for such infections, we screened, in the hamster-B. microti system, 12 antiprotozoal drugs that have either recently been released for human use or were in experimental stages of development at the Walter Reed Army Institute of Research for the treatment of malaria and leishmaniasis. Several well-recognized antimalarial drugs, such as mefloquine, halofantrine, artesunate, and artelenic acid, exhibited little or no effect on parasitemia. Two 8-aminoquinolines, WR006026 [8-(6-diethylaminohexylamino)-6-methoxy-4-methylquinoline dihydrochloride] and WR238605 [8-[(4-amino-1-methylbutyl)amino]-2,6-dimethoxy-4-methyl-5 -(3-trifluoromethylphenoxy-7) quinoline succinate], produced clearance of patent parasitemia. Furthermore, blood from infected hamsters treated with WR238605 via an intramuscular injection failed to infect naive hamsters on subpassage, thus producing a parasitologic cure. These two compounds merit further screening in other systems and may prove useful in treating human babesiosis.

Isolation of the equine granulocytic ehrlichiosis agent, Ehrlichia equi, in tick cell culture

The equine granulocytic ehrlichiosis agent, Ehrlichia equi, is closely related or identical to the human granulocytic ehrlichiosis (HGE) agent. Both are suspected of being transmitted by ticks. We have successfully isolated E. equi in a cell line, IDE8, derived from a putative vector, the tick Ixodes scapularis. Peripheral blood leukocytes from an experimentally infected horse were inoculated onto IDE8 monolayers. Cultures were incubated in a candle jar at 34 degrees C in tick cell culture medium with NaHCO3 and an organic buffer [3-(N-morpholino)-propanesulfonic acid] (MOPS). Within 2 weeks, infected cells were detected in Giemsa-stained culture samples, and the organisms subsequently spread to uninfected cells in the cultures. E. equi was passaged serially by transferring a portion of an infected culture to new cell layers every 2 to 3 weeks. The identity of the organisms was confirmed by PCR using oligonucleotide primers specific for E. equi and the HGE agent and by immunocytology. Homologous equine antibodies and human anti-HGE convalescent serum recognized E. equi grown in tick cell culture. Electron microscopy revealed electron-lucent and -dense ehrlichia-like forms developing within host cell endosomes. E. equi passaged twice in tick cell culture retained infectivity and pathogenicity for the equine host, as demonstrated by intravenous inoculation of a suspension of infected tick cells and subsequent reisolation from peripheral blood, in fulfillment of Koch's postulates. The horse developed severe clinical signs, i.e., fever, inappetence, thrombocytopenia, icterus, and limb edema, typical of granulocytic equine ehrlichiosis, within 1 week.