Diagnosis of babesiosis using an immunoblot serologic test

Analysis of serum proteomic profiles of endangered Siamese and Burmese Eld's deer infected with subclinical Babesia bovis in Thailand

The endangered Eld's deer is a conserved species in Thailand, where tropical parasitic infections are endemic. Although Eld's deer with babesiosis are generally asymptomatic, they can still harbor the parasite and serve as reservoirs for ticks, spreading the infection to healthy animals within the herd. The present study aimed to investigate potential serum proteome biomarkers of Eld's deer with subclinical Babesia bovis infection. A total of 67 blood samples were collected from captive Siamese and Burmese Eld's deer showing no signs of parasitic infection. The nested polymerase chain reaction (nPCR) of a conserved spherical body protein 2 (sbp-2) gene of B. bovis was utilized to classify Eld's deer groups, with 25.37 % (17/67) testing positive for B. bovis. Additionally, the application of proteomic studies showed that six B. bovis proteins, such as Obg-like ATPase 1 (OLA1) and heat shock protein 90 (HSP90), were significantly upregulated by more than a two-fold change compared with the PCR-negative samples. Of the 55 overexpressed serum proteins in the PCR-positives, alpha 2-HS glycoprotein (AHSG) and immunoglobulin lambda variable 2-8 (IGLV2-8) were notably among the top 10 proteins with the highest area under curve (AUC) values. Hence, they were proposed as potential biomarkers for subclinical B. bovis infection in Eld's deer. Analysis of the protein interaction network revealed interactions between Eld's deer AHSG and B. bovis OLA1 and HSP90, alongside associations with other proteins such as erb-b2 receptor tyrosine kinase 2 (ERBB2) and epidermal growth factor receptor (EGFR). These interactions were involved in the immune system pathway and inflammatory responses. Our findings shed light on subclinical infection of B. bovis in Eld's deer and identify potential biomarkers, contributing to the further effective detection and monitoring of B. bovis infection in this endangered species.

Tick-Borne Illnesses in Emergency and Wilderness Medicine

This review highlights the causative organisms, clinical features, diagnosis, and treatment of the most common tick-borne illnesses in the United States, including Lyme disease, Rocky Mountain spotted fever, anaplasmosis, ehrlichiosis, tularemia, Powassan virus, and alpha-gal syndrome. Tick bite prevention strategies and some basic tick removal recommendations are also provided.

Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA): 2020 Guideline on Diagnosis and Management of Babesiosis

The purpose of this guideline is to provide evidence-based guidance for the most effective strategies for the diagnosis and management of babesiosis. The diagnosis and treatment of co-infection with babesiosis and Lyme disease will be addressed in a separate Infectious Diseases Society of America (IDSA), American Academy of Neurology (AAN), and American College of Rheumatology (ACR) guideline [1]. Recommendations for the diagnosis and treatment of human granulocytic anaplasmosis can be found in the recent rickettsial disease guideline developed by the Centers for Disease Control and Prevention [2]. The target audience for the babesiosis guideline includes primary care physicians and specialists caring for this condition, such as infectious diseases specialists, emergency physicians, intensivists, internists, pediatricians, hematologists, and transfusion medicine specialists.

Frequency and magnitude of seroreactivity to Babesia microti in 245 patients diagnosed by PCR in New York State

Multiple methodologies have been used to detect antibodies to Babesia microti. Use of an indirect immunofluorescence assay (IFA) has been the most widely used approach, but IFAs have varied as to which antibody class or classes are being detected and in regard to cutoff titers. In this study, 245 different patients with polymerase chain reaction (PCR)-confirmed B. microti infection were tested by a polyvalent IFA using serum collected within 3 days of the date the blood sample for PCR testing was obtained. Of the 245 patients, 243 (99.2%) had a positive serologic test result (i.e., ≥1:64). Of the 243 patients who were seropositive, 242 (99.6%) had a titer of ≥1:256, 236 (97.1%) had a titer of ≥1:512, and 210 (86.4%) had a titer of ≥1:1024. In conclusion, high titer seropositivity based on a polyvalent IFA is to be expected at the time of PCR confirmation of active babesiosis in clinical practice.

Analysis of antigen-antibody cross-reactivity among lineages and sublineages of Babesia microti parasites using human babesiosis specimens

BACKGROUND

Human babesiosis is caused mainly by Babesia microti and has recently become a public health concern due to an increase in transfusion-transmitted infection. Thus, the development of an antibody detection method with high specificity and sensitivity is a priority. Seroreactivity against B. microti has been reported to be highly specific not only to B. microti lineages but also to sublineages. This study aimed to elucidate the human antibody reactivity against various lineages, including US, Kobe, and Hobetsu, and sublineages (North America and East Asia) in the US lineage.

STUDY DESIGN AND METHODS

Twenty samples obtained from individuals infected with B. microti in the United States were tested for the presence of anti-B. microti antibodies using indirect immunofluorescence assay (IFA) and Western blotting (WB) to indicate antigens of each (sub-)lineage.

RESULTS

By IFA, 20 samples showed reactivity to the North America sublineage (titer range, 64-4096), 16 to the East Asia sublineage (64-512), 10 to the Kobe (64-128), and five to the Hobetsu (64). Antibody titers to the East Asia sublineage, Kobe, and Hobetsu were significantly lower than those to the North America sublineage (p < 0.01). By WB, in parallel with the IFA results, 18 samples showed strong reactions to the North America sublineage, weak reactions to the East Asia sublineage, and near-zero reactions to the Kobe and Hobetsu.

CONCLUSION

Human antibodies induced by B. microti infection are highly specific against B. microti lineages and sublineages with low cross-reactivity. Developing a precise antibody detection method may require specific antigens based on B. microti lineages and sublineages.

Screening of patient blood samples for babesiosis using enzymatic assays

Human babesiosis is an emerging tick-borne disease in the United States and Europe. Transmitted by Ixodes ticks, the causative agent Babesia microti is an intraerythrocytic parasite that causes mild to deadly disease. Transmission of B. microti can also occur by transfusion of infected blood and blood products resulting in transfusion-transmitted babesiosis (TTB), which carries a high risk of fatality. To effectively manage this rise in B. microti infections, better screening tools are needed, which require minimal manipulation of the samples before testing. To this end, we tested two enzymatic assays, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), for efficacy in diagnosis of babesiosis. The results show that AST and ALT activity is significantly higher in the plasma of B. microti-infected patients. Moreover, statistical analysis revealed that these assays have high sensitivity and positive predictive values, which highlights their usefulness as diagnostics for babesiosis. These standardized enzymatic assays can be used to perform high-throughput, large-scale screens of blood and blood products before they are certified safe for transfusion.

Serologic screening of United States blood donors for Babesia microti using an investigational enzyme immunoassay

BACKGROUND

The tick-borne pathogen Babesia microti has become recognized as the leading infectious risk associated with blood transfusion in the United States, yet no Food and Drug Administration-licensed screening tests are currently available to mitigate this risk. The aim of this study was to evaluate the performance of an investigational enzyme immunoassay (EIA) for B. microti as a screening test applied to endemic and nonendemic blood donor populations.

STUDY DESIGN AND METHODS

The study aimed to test 20,000 blood donors from areas of the United States considered endemic for B. microti and 10,000 donors from a nonendemic area with the investigational B. microti EIA. Repeat-reactive samples were retested by polymerase chain reaction (PCR), blood smear, immunofluorescent assay (IFA), and immunoblot assay. In parallel, serum samples from symptomatic patients with confirmed babesiosis were tested by EIA, IFA, and immunoblot assays.

RESULTS

A total of 38 of 13,757 (0.28%) of the donors from New York, 7 of 4583 (0.15%) from Minnesota, and 11 of 8363 (0.13%) from New Mexico were found repeat reactive by EIA. Nine of the 56 EIA repeat-reactive donors (eight from New York and one from Minnesota) were positive by PCR. The specificity of the assay in a nonendemic population was 99.93%. Among IFA-positive clinical babesiosis patients, the sensitivity of the assay was 91.1%.

CONCLUSION

The B. microti EIA detected PCR-positive, potentially infectious blood donors in an endemic population and exhibited high specificity among uninfected and unexposed individuals. The EIA promises to provide an effective tool for blood donor screening for B. microti in a format amenable to high-throughput and cost-effective screening.

Human babesiosis, an emerging tick-borne disease in the People's Republic of China

Babesiosis is a typical zoonotic, emerging disease caused by a tick-borne intraerythrocytic protozoan of Babesia spp. that also can be transmitted by blood transfusion. Babesiosis imposes an increasing public-health threat. We reviewed and mapped epidemiological studies on Babesia in vectors and/or rodents in the People’s Republic of China (P.R. China) and found that B. microti was the predominant species detected in the investigated regions such as Heilongjiang, Zhejiang, Fujian provinces and Taiwan island. We reviewed a series of sporadic human babesiosis cases collected from 1940’s to 2013, in Yunnan, Inner Mongolia, Taiwan and Zhejiang and other regions including a main endemic area of malaria on the China-Myanmar border areas in P.R. China. Clinical manifestations of human babesiosis were also reviewed. Human babesiosis may have previously been overlooked in P.R. China due to a lack of medical awareness and the limitation of clinical diagnostic methods.

Cost-effectiveness of blood donor screening for Babesia microti in endemic regions of the United States

BACKGROUND

Babesia microti is the leading reported cause of red blood cell (RBC) transfusion-transmitted infection in the United States. Donor screening assays are in development.

STUDY DESIGN AND METHODS

A decision analytic model estimated the cost-effectiveness of screening strategies for preventing transfusion-transmitted babesiosis (TTB) in a hypothetical cohort of transfusion recipients in Babesia-endemic areas of the United States. Strategies included: 1) no screening; 2) Uniform Donor Health History Questionnaire (UDHQ), "status quo"; 3) recipient risk targeting using donor antibody and polymerase chain reaction (PCR) screening; 4) universal endemic donor antibody screening; and 5) universal endemic donor antibody and PCR screening. Outcome measures were TTB cases averted, costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs; $/QALY). We assumed a societal willingness to pay of $1 million/QALY based on screening for other transfusion-transmitted infections.

RESULTS

Compared to no screening, the UDHQ avoids 0.02 TTB cases per 100,000 RBC transfusions at an ICER of $160,000/QALY whereas recipient risk-targeted strategy using antibody/PCR avoids 1.62 TTB cases per 100,000 RBC transfusions at an ICER of $713,000/QALY compared to the UDHQ. Universal endemic antibody screening avoids 3.39 cases at an ICER of $760,000/QALY compared to the recipient risk-targeted strategy. Universal endemic antibody/PCR screening avoids 3.60 cases and has an ICER of $8.8 million/QALY compared to universal endemic antibody screening. Results are sensitive to blood donor Babesia prevalence, TTB transmission probability, screening test costs, risk and severity of TTB complications, and impact of babesiosis diagnosis on donor quality of life.

CONCLUSION

Antibody screening for Babesia in endemic regions is appropriate from an economic perspective based on the societal willingness to pay for preventing infectious threats to blood safety.

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 babesiosis in the United States: summary of a workshop

Infections of humans with intraerythrocytic parasites of the genus Babesia can be locally prevalent in diverse regions of the United States. Transfusion of blood and blood products collected from donors infected with Babesia may result in a serious illness that can be fatal. In September 2008, the Food and Drug Administration organized a public workshop to discuss the various aspects of transfusion-transmitted babesiosis in the United States including the possible strategies to identify and defer blood donors who may have been infected with Babesia. Discussions were also held on the biology, pathogenesis, and epidemiology of Babesia species. In this article, we summarize the scientific presentations and panel discussions that took place during the workshop.

Identity of the causal agents of human babesiosis in Europe

Most cases of human babesiosis are caused either by Babesia divergens in Europe or Babesia microti in America. B. microti, once regarded as a single species, occurs as a world-wide species complex and although both phenotypic and genotypic features lend support to suggestions that zoonotic B. microti may occur in Europe, convincing medical evidence is lacking. Several B. divergens-like parasites have emerged in the last few years, but 18S rRNA gene analysis suggests that B. divergens 'sensu stricto' is restricted to European (and North African) cattle. Some of the B. divergens-like parasites only differ from the bovine type by a few bases, and it remains to be determined whether this is sufficient to accord them separate species status. Comparative biology should support genetic data in taxonomic studies of both B. divergens and B. microti.

Comparison of four diagnostic tests for the identification of serum antibodies in small ruminants infected withMycoplasma agalactiae

AIM

To determine the diagnostic capability of a newly developed Western blot (WB) assay for the detection of serum antibodies against Mycoplasma agalactiae compared with conventional serological tests, and to identify the best test for routine diagnostic use.

METHODS

The serological test methods used were: two commercial indirect enzyme-linked immunosorbent assays (ELISA), viz ELISA-1, using a bacterial antigen preparation, and ELISA-2, using a recombinant protein (lipoprotein p48) antigen; the complement fixation test (CFT); and a newly developed WB assay, the latter both using a bacterial antigen preparation. Thirty sera from goats infected with M. agalactiae and 97 sera from non-infected sheep were tested using all four methods.

RESULTS

Staining patterns in the WB were quite variable. An immuno-dominant band of 41 kDa was detected in 63% of sera from infected animals. The same band also appeared, although mostly very weakly, in 10% of sera from non-infected animals. When suspicious or very weak reactors were omitted, the diagnostic sensitivity (DSE) and diagnostic specificity (DSP), respectively, for the four assays were: WB=56.7%, 97.9%; ELISA-1=76.7%, 99.0%; ELISA-2=56.7%, 100%; and CFT=40.0%, 94.8%.

CONCLUSIONS

ELISA-1 performed best in this comparison. While the WB can be used, it did not have a technical advantage over the ELISA. The CFT should be discouraged as the primary screening method for contagious agalactia and should be replaced by ELISA-1. Results from this study confirm that serological test methods for contagious agalactia are useful for the detection of infected flocks but will not detect every individual infected animal.

Serological diagnosis of human babesiosis by IgG enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (ELISA) for the detection of IgG antibodies to Babesia microti antigen was developed. B. microti antigens were harvested from experimentally infected hamster blood and used as a coating antigen. The sensitivity and specificity of the IgG ELISA relative to immunofluorescent antibody assay (IFA) testing was 95.5% and 94.1%, respectively. According to the receiver operating characteristic curve analysis, the area under the curve was 0.987. No cross-reactivity of serum samples collected from patients infected with Toxoplasma gondii, Borrelia burgdorferi, Anaplasma phagocytophilum, Bartonella quintana, Dengue virus, or West Nile virus was detected. Cross-reactivity was observed with one of 35 sera from patients infected with Bartonella henselae. These results indicate that the established ELISA methods could be utilized as an accurate measure for the clinical diagnosis of human babesiosis.

Risk and prevention of transfusion-transmitted babesiosis and other tick-borne diseases

PURPOSE OF REVIEW

Tick-borne diseases have increasingly been recognized in the United States as public health problems. The importance of tick-borne diseases has been accelerated by increases in animal populations, as well as increased human recreation in wooded environments that are conducive to tick bites. Babesiosis, usually caused by the intraerythrocytic parasite, Babesia microti and transmitted by the same tick as Lyme disease, has important transfusion implications. Although Lyme disease has not been reported from blood transfusion, newly identified tick-borne diseases such as ehrlichiosis raise additional questions about the role of the tick in transfusion-transmitted diseases.

RECENT FINDINGS

The risk of transfusion-transmitted babesiosis is higher than usually appreciated and in endemic areas represents a major threat to the blood supply. Furthermore, the geographic range of B. microti is expanding, other Babesia spp. have been implicated in transfusion transmission in the western United States, and the movement of blood donors and donated blood components may result in the appearance of transfusion babesiosis in areas less familiar with these parasites. Consequently, a higher degree of clinical suspicion will allow early recognition and treatment of this important transfusion complication.

SUMMARY

In endemic areas transfusion-transmitted babesiosis is more prevalent than usually believed. The extension of the geographic range of various Babesia spp. and the movement of donors and blood products around the United States has resulted in the risk extending to non-endemic areas. Clinicians should maintain a high degree of clinical suspicion for transfusion-transmitted babesiosis.

Dermatoses from ticks

Ticks are ectoparasites that cause dermatologic disease directly by their bite and indirectly as vectors of bacterial, rickettsial, protozoal, and viral diseases. In North America, where ticks are the leading cause of vector-borne infection, dermatologists should recognize several tick species. Basic tick biology and identification will be reviewed. Tick bites cause a variety of acute and chronic skin lesions. The tick-borne diseases include Lyme disease, tick-borne relapsing fever, tularemia, babesiosis, Rocky Mountain spotted fever, other spotted fevers, ehrlichiosis, Colorado tick fever, and others. The epidemiology, clinical features, diagnosis, and treatment of these diseases are reviewed with an emphasis on cutaneous manifestations. Finally, the prevention of diseases caused by ticks is reviewed.

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.

Cellular immunity, but not gamma interferon, is essential for resolution of Babesia microti infection in BALB/c mice

A new strain of Babesia microti (KR-1) was isolated from a Connecticut resident with babesiosis by hamster inoculation and adapted to C3H/HeJ and BALB/c mice. To examine the relative importance of humoral and cellular immunity for the control of B. microti infection, we compared the course of disease in wild-type BALB/c mice with that in BALB/c SCID mice, JHD-null (B-cell-deficient) mice, and T-cell receptor alphabeta (TCRbeta(-/-)) or gamma interferon (IFN-gamma) (IFN-gamma(-/-)) knockout mice following inoculation with the KR-1-strain. SCID mice and TCRalphabeta knockouts sustained a severe but nonlethal parasitemia averaging 35 to 45% infected erythrocytes. IFN-gamma-deficient mice developed a less severe parasitemia but were able to clear the infection. In contrast, in six of eight JHD-null mice, the levels of parasitemia were indistinguishable from those in the wild-type animals. These data indicate that cellular immunity is critical for the clearance of B. microti in BALB/c mice but that disease resolution can occur even in the absence of IFN-gamma.

Tick-borne diseases in transfusion medicine

Ticks are effective vectors of viral, bacterial, rickettsial and parasitic diseases. Many of the tick-borne diseases (TBDs) are of significance to transfusion medicine, either because of the risks they pose to the blood supply or the necessity for blood products required in their treatment. The transmission of tick-borne pathogens via blood transfusion is of global concern. However, among transfusion medicine practitioners, experience with most of these microorganisms is limited. Transfusion transmission of TBDs has been documented largely by means of single case reports. A better understanding of the epidemiology, biology and management of this group of diseases is necessary in order to assess the risks they pose to the blood supply and to help guide effective prevention strategies to reduce this risk. Unique methods are required to focus on donor selection, predonation questioning, mass screening and inactivation or eradication procedures. The role of the transfusion medicine service in their treatment also needs to be better defined. This article reviews the growing body of literature pertaining to this emerging field of transfusion medicine and offers some recommendations for transfusionists in dealing with TBDs.