Context-Specific Procedures for the Diagnosis of Human Schistosomiasis – A Mini Review

Schistosomiasis is a parasitic disease caused by trematode blood flukes of the genus Schistosoma, affecting over 250 million people mainly in the tropics. Clinically, the disease can present itself with acute symptoms, a stage which is relatively more common in naive travellers originating from non-endemic regions. It can also develop into chronic disease, with the outcome depending on the Schistosoma species involved, the duration and intensity of infection and several host-related factors. A range of diagnostic tests is available to determine Schistosoma infection, including microscopy, antibody detection, antigen detection using the Point-Of-Care Circulating Cathodic Antigen (POC-CCA) test and the Up-Converting Particle Lateral Flow Circulating Anodic Antigen (UCP-LF CAA) test, as well as Nucleic Acid Amplification Tests (NAATs) such as real-time PCR. In this mini review, we discuss these different diagnostic procedures and explore their most appropriate use in context-specific settings. With regard to endemic settings, diagnostic approaches are described based on their suitability for individual diagnosis, monitoring control programs, determining elimination as a public health problem and eventual interruption of transmission. For non-endemic settings, we summarize the most suitable diagnostic approaches for imported cases, either acute or chronic. Additionally, diagnostic options for disease-specific clinical presentations such as genital schistosomiasis and neuro-schistosomiasis are included. Finally, the specific role of diagnostic tests within research settings is described, including a controlled human schistosomiasis infection model and several clinical studies. In conclusion, context-specific settings have different requirements for a diagnostic test, stressing the importance of a well-considered decision of the most suitable diagnostic procedure.

Current and emerging trends in point-of-care urinalysis tests

Introduction: The development of point-of-care testing (POCT) has made clinical diagnostics available, affordable, rapid, and easy to use since the 1990s.The significance of this platform rests on its potential to empower patients to monitor their own health status more frequently, in the convenience of their home, so that diseases can be diagnosed at the earliest possible time-point. Recent advances have expanded traditional formats such as qualitative or semi-quantitative dipsticks and lateral flow immunoassays to newer platforms such as microfluidics and paper-based assays where signals can be measured quantitatively using handheld devices.Areas covered: This review discusses: (1) working principles and operating mechanisms of both existing and emerging POCT platforms, (2) urine analytes measured using POCT in comparison to the laboratory or clinical 'gold standard,' and (3) limitations of existing POCT and expectations of emerging POCT in urinalysis.Expert opinion: Currently, a variety of biological samples such as urine, saliva, serum, plasma, and other fluids can be applied to POCT for quick diagnosis, especially in resource-limited settings. Emerging platforms will increasingly empower individuals to monitor their health status through frequent urine analysis even from their homes. The impact of these emerging technologies on healthcare is likely to be transformative.

Imported human Schistosoma japonicum: A report on two cases in Filipino migrants present in Italy and a systematic review of literature

BACKGROUND

Schistosoma japonicum is endemic in the Philippines, China, and Indonesia, and is the third-most common schistosoma species. The infection can be asymptomatic for years but, if left untreated, can lead to irreversible complications.

METHOD

We report the results of a systematic review of the literature on imported S. japonicum infection and describe two previously unpublished cases diagnosed in Filipino migrants in Italy.

RESULTS

Twenty-five imported cases of S. japonicum schistosomiasis were retrieved. All patients but one were migrants. Most subjects acquired the infection in Philippines (n = 18, 72%). Median age at diagnosis was 46 years. Median period of residence in non-endemic countries before diagnosis was 14.5 years. Cases of prevalent hepatosplenic involvement were 10 (40%), those with prevalent intestinal involvement were 10 (40%), whereas five (20%) had overlapping manifestations. Ten patients suffered from cirrhosis; two underwent liver transplantation. Three patients presented with acute abdomen due to intestinal complications, leading to explorative laparotomy. In all cases, but one, the diagnosis was based on a histological examination of biopsy specimen, revealing S. japonicum ova. Seventeen patients were treated with praziquantel, and in three of them, possible treatment failures occurred.

CONCLUSIONS

S. japonicum infection is uncommonly reported in non-endemic areas, but is probably underestimated because of a low threshold awareness of clinicians and unavailability of specific diagnostic tools. Viable S. japonicum adults may persist for decades, indicating that migrants or travellers previously exposed in areas with high-risk areas can harbour viable worms and deserve treatment.

Sensitivity of the Point-of-Care Circulating Cathodic Antigen Urine Cassette Test for Diagnosis of Schistosoma mansoni in Low-Endemicity Settings in Côte d'Ivoire

The sensitivity of a point-of-care circulating cathodic antigen (POC-CCA) urine cassette test for diagnosis of Schistosoma mansoni in low-endemicity settings is poorly understood. We conducted a cross-sectional survey in 14 villages in western Côte d'Ivoire and diagnosed children aged 9-12 years for schistosomiasis. Two stool samples were subjected to triplicate Kato-Katz thick smears each for diagnosis of S. mansoni, whereas a single urine sample was examined by POC-CCA for S. mansoni, filtration for Schistosoma haematobium, and reagent strip for microhematuria. According to the Kato-Katz technique, we found 45 out of 681 children positive for S. mansoni (6.6%) with a mean intensity among infected children of 72.2 eggs per gram of stool. Point-of-care circulating cathodic antigen revealed a prevalence of S. mansoni of 33.0% when trace results were considered positive and 12.5% when trace results were considered negative. Eggs of S. haematobium were found in eight participants (1.2%), whereas the prevalence of microhematuria was 13.5%. A single POC-CCA urine cassette test revealed a several-fold higher prevalence of S. mansoni than multiple Kato-Katz thick smears in this low-endemicity area. Our findings have important ramifications for choosing an appropriate diagnostic tool in low-endemic areas that might be targeted for elimination.

Concordance of the point-of-care circulating cathodic antigen test for the diagnosis of intestinal schistosomiasis in a low endemicity area

Background

The Kato-Katz technique is recommended worldwide for the diagnosis of intestinal schistosomiasis, detecting parasite eggs in feces of infected people. However, new tests have been developed in order to facilitate diagnosis, e.g. by detection of specific antigens secreted by schistosomes, such as the circulating cathodic antigen (CCA). The aim of this study was to evaluate the performance of the point-of-care circulating cathodic antigen test (POC-CCA) compared to the Kato-Katz technique in a low prevalence area in the Amazon Region, located in the municipality of Primavera, State of Pará, Brazil.

Methods

Positivity rates of the POC-CCA test and the Kato-Katz technique were calculated. The sensitivity, specificity, accuracy and kappa coefficient were determined by comparing both methods. The reference standard was established using 16 Kato-Katz slides, 12 of the first fecal sample, two of the second and two of the third one. The study also included the concordance between POC-CCA results and different numbers and combinations of Kato-Katz slides.

Results

The prevalence of schistosomiasis according to the reference standard or POC-CCA test reached a rate of 9.4% or 23.9%, respectively, among a total of 372 participants. The positivity rates by the Kato-Katz technique increased from 2.4 to 9.4%, according to the increase in the number of slides examined and fecal samples collected. A sensitivity of 55.6%, specificity 76.9%, accuracy 76% and κ coefficient of 0.06 was observed by comparing one slide of the first sample and POC-CCA. Comparing 6 slides from three different samples, two slides of each, with POC-CCA resulted in a sensitivity of 58.3%, specificity 78.4%, accuracy 77% and κ coefficient of 0.16. Finally, the comparison of 16 slides from three different samples with POC-CCA revealed a sensitivity of 65.7%, specificity 80.4%, accuracy 79%, and κ coefficient of 0.27.

Conclusions

The immunochromatographic test has the potential to be an important tool to combat schistosomiasis because of its practicality and applicability but should be applied with caution in low prevalence areas and in programs that aim to eliminate this disease.

Trial registration

CAAE#21824513.9.0000.5091. January 31st, 2014.

Electronic supplementary material

The online version of this article (10.1186/s40249-019-0551-7) contains supplementary material, which is available to authorized users.

Refining Diagnosis of Schistosoma haematobium Infections: Antigen and Antibody Detection in Urine

Background: Traditional microscopic examination of urine or stool for schistosome eggs lacks sensitivity compared to measurement of schistosome worm-derived circulating antigens in serum or urine. The ease and non-invasiveness of urine collection makes urine an ideal sample for schistosome antigen detection. In this study several user-friendly, lateral-flow (LF) based urine assays were evaluated against a composite reference that defined infection as detection of either eggs in urine or anodic antigen in serum. Method: In a Tanzanian population with a S. haematobium prevalence of 40-50% (S. mansoni prevalence <2%), clinical samples from 44 women aged 18 to 35 years were analyzed for Schistosoma infection. Urine and stool samples were examined microscopically for eggs, and serum samples were analyzed for the presence of the anodic antigen. Urines were further subjected to a set of LF assays detecting (circulating) anodic (CAA) and cathodic antigen (CCA) as well as antibodies against soluble egg antigens (SEA) and crude cercarial antigen preparation (SCAP). Results: The urine LF anodic antigen assay utilizing luminescent upconverting reporter particles (UCP) confirmed its increased sensitivity when performed with larger sample volume. Qualitatively, the anodic antigen assay performed on 250 μL urine matched the performance of the standard anodic antigen assay performed on 20 μL serum. However, the ratio of anodic antigen levels in urine vs. serum of individual patients varied with absolute levels always higher in serum. The 10 μL urine UCP-LF cathodic antigen assay correlated with the commercially available urine POC-CCA (40 μL) test, while conferring better sensitivity with a quantitative result. Urinary antibodies against SEA and SCAP overlap and correlate with the presence of urinary egg and serum anodic antigen levels. Conclusions: The UCP-LF anodic antigen assay using 250 μL of urine is an expedient user-friendly assay and a suitable non-invasive alternative to serum-based antigen testing and urinary egg detection. Individual biological differences in the clearance process of the circulating antigens are thought to explain the observed high variation in the type and level of antigen (anodic or cathodic) measured in urine or serum. Simultaneous detection of anodic and cathodic antigen may be considered to further increase accuracy.

Infectious disease profiles of Syrian and Eritrean migrants presenting in Europe: A systematic review

BACKGROUND

In the past decade, a large influx of migrants presented in Europe. Their country of origin was mainly either Syria or Eritrea. Public health institutions in host countries in Europe are challenged to screen and care for migrant populations with regard to infectious diseases.

METHODS

We performed a systematic literature review (according to PRISMA guidelines) to define the infectious disease profile of migrants originating in Syria and Eritrea.

RESULTS

The search resulted in 825 papers of possible relevance for infectious diseases in migrants from Syria, of which, after screening, we included 35 in the systematic review. A further 265 papers of possible relevance for infectious diseases in Eritrean migrants were screened, of which we included 27 in the systematic review. In migrants from Syria, leishmaniasis was the most frequently reported infectious disease. In addition, colonisation with drug resistant, Gram-negativ bacteria was reported. In the Eritrean migrants the infectious disease most described in the selected papers was louse-borne relapsing fever. Other frequently reported infectious diseases were scabies and Plasmodium vivax malaria.

CONCLUSION

Our systematic analysis defines the profiles of infectious diseases for migrants from Syria and Eritrea and serves as an evidence base for public health screening and care of presenting migrants.

Diagnostic study on an immunochromatographic rapid test for schistosomiasis: comparison between use on serum and on blood spot from fingerprick

BACKGROUND

An immunochromatographic rapid test (ICT; Schistosoma ICT IgG-IgM, LDBIO Diagnostics) demonstrated high sensitivity (96%) in the diagnosis of Schistosoma mansoni and S. haematobium. To date, the test has been validated for use on serum only, but in the absence of lab equipment, blood drop from fingerprick could be a useful option. This method is acquiring more interest because of the high flow of migrants rapidly moving across Italy and other European countries.

OBJECTIVE

The aim of this prospective study was to evaluate the use of ICT on whole blood obtained from fingerprick.

SETTING

Centre for Tropical Diseases (CTD), Sacro Cuore Don Calabria Hospital, Negrar, Verona, Italy.

PARTICIPANTS

The inclusion criteria were African migrants aged ≥18 years with epidemiological risk of infection. The exclusion criteria were refusal to participate in the study and impossibility of execution of one of the two study methods, for any reason. Seventy of the 72 eligible patients completed the study, 79% of whom were male.

INTERVENTIONS

The ICT was performed twice for each included patient: one on blood drop (by the research nurses, in the ward) and one on serum (by staff of CTD lab). The primary outcome was the concordance between the two methods, assessed by Cohen's kappa.

RESULTS

Cohen's kappa was 0.45 (95% CI 27.0 to 63.6), indicating moderate agreement between the ICT on serum and the ICT on blood drop. Assuming the results on serum as reference standard for diagnosis, the sensitivity and specificity of ICT on blood drop were 55% (95% CI 40 to 69) and 93% (95% CI 79 to 98), respectively.

CONCLUSIONS

The agreement between the two diagnostic methods is too low to support the alternative one. Implementation of the kit for using blood drop instead of the serum and/or further studies aimed to identify easy-to-use tests for schistosomiasis feasible outside referral centres for tropical diseases are needed.

Rapid clearance of Schistosoma mansoni circulating cathodic antigen after treatment shown by urine strip tests in a Ugandan fishing community - Relevance for monitoring treatment efficacy and re-infection

Schistosomiasis control and elimination has priority in public health agendas in several sub-Saharan countries. However, achieving these goals remains a substantial challenge. In order to assess progress of interventions and treatment efficacy it is pertinent to have accurate, feasible and affordable diagnostic tools. Detection of Schistosoma mansoni infection by circulating cathodic antigen (CCA) in urine is an attractive option as this measure describes live worm infection noninvasively. In order to interpret treatment efficacy and re-infection levels, knowledge about clearance of this antigen is necessary. The current study aims to investigate, whether antigen clearance as a proxy for decreasing worm numbers is reflected in decreasing CCA levels in urine shortly after praziquantel treatment. Here CCA levels are measured 24 hours post treatment in response to both a single and two treatments. The study was designed as a series of cross-sectional urine and stool sample collections from 446 individuals nested in a two-arm randomised single blinded longitudinal clinical trial cohort matched by gender and age (ClinicalTrials.gov Identifier: NCT00215267) receiving one or two praziquantel treatments. CCA levels in urine were determined by carbon-conjugated monoclonal antibody lateral flow strip assay and eggs per gram faeces for S. mansoni and soil-transmitted helminths by Kato-Katz. Significant correlations between CCA levels and S. mansoni egg count at every measured time point were found and confirmed the added beneficial effect of a second treatment at two weeks after baseline. Furthermore, presence of hookworm was found not to be a confounder for CCA test specificity. Twenty-four hours post treatment measures of mean CCA scores showed significant reductions. In conclusion, removal of CCA in response to treatment is detectable as a decline in CCA in urine already after 24 hours. This has relevance for use and interpretation of laboratory based and point-of-care CCA tests in terms of treatment efficacy and re-infection proportions as this measure provides information on the presence of all actively feeding stages of S. mansoni, which conventional faecal microscopy methods do not accurately reflect.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00215267.

PCR-based verification of positive rapid diagnostic tests for intestinal protozoa infections with variable test band intensity

Stool-based rapid diagnostic tests (RDTs) for pathogenic intestinal protozoa (e.g. Cryptosporidium spp. and Giardia intestinalis) allow for prompt diagnosis and treatment in resource-constrained settings. Such RDTs can improve individual patient management and facilitate population-based screening programmes in areas without microbiological laboratories for confirmatory testing. However, RDTs are difficult to interpret in case of 'trace' results with faint test band intensities and little is known about whether such ambiguous results might indicate 'true' infections. In a longitudinal study conducted in poor neighbourhoods of Port Elizabeth, South Africa, a total of 1428 stool samples from two cohorts of schoolchildren were examined on the spot for Cryptosporidium spp. and G. intestinalis using an RDT (Crypto/Giardia DuoStrip; Coris BioConcept). Overall, 121 samples were positive for G. intestinalis and the RDT suggested presence of cryptosporidiosis in 22 samples. After a storage period of 9-10 months in cohort 1 and 2-3 months in cohort 2, samples were subjected to multiplex PCR (BD Max™ Enteric Parasite Panel, Becton Dickinson). Ninety-three percent (112/121) of RDT-positive samples for G. intestinalis were confirmed by PCR, with a correlation between RDT test band intensity and quantitative pathogen load present in the sample. For Cryptosporidium spp., all positive RDTs had faintly visible lines and these were negative on PCR. The performance of the BD Max™ PCR was nearly identical in both cohorts, despite the prolonged storage at disrupted cold chain conditions in cohort 1. The Crypto/Giardia DuoStrip warrants further validation in communities with a high incidence of diarrhoea.

Epidemiological, clinical, diagnostic and economic features of an immigrant population of chronic schistosomiasis sufferers with long-term residence in a non-endemic country (North Metropolitan area of Barcelona, 2002-2016)

Background

Schistosomiasis, one of the neglected tropical diseases (NTD) listed by the WHO, is an acute and chronic parasitic disease caused by blood flukes (trematode worms) of the genus Schistosoma. Complications of long-term infestation include liver cirrhosis, bladder tumors and kidney failure. The objective of this study was to carry out a clinical and epidemiological characterization of a schistosomiasis-diagnosed immigrant population with long-term residencein the EU as well as to evaluate the diagnostic methods available to date.

Methods and results

A total of 61 individuals with Schistosoma infection who received medical attention between June 2002 and June 2016 at the North Metropolitan International Health Unit in Barcelona (Catalonia, Spain), were included in the study. All patients were sub-Saharan African immigrants. The majority were male (91.8%) with a median age of 34 years. Symptoms attributable to infection such as haematuria, abdominal pain and dysuria were recorded in up to 90% of patients. The percentage of eosinophils decreased amongst older patients (p = 0.002) and those with symptoms associated with urinary tract infections (p = 0.017). Serology was used for diagnosis in 80.3% of the cases, with microscopic examination showing the remaining 9.8% positive for parasite eggs. Direct microbiological diagnosis was more useful in patients with less than 5 years of residence in the EU (p = 0.05). Chronic complications were present in 22 (36%) of the patients, with renal failure affecting 20 (33%). Of these 20, 6(10%) developed terminal renal failure and required hemodialysis, while 3 (5%) received a renal transplantation.

Conclusion

Morbidity associated with chronic long-term schistosomiasis is frequent among African immigrants in non-endemic countries. Better diagnostic tools and appropriate early treatment would prevent the development of visceral damage. Thorough screening in selected patients would also be useful to avoid chronic complications.

Spectrum of infectious diseases among newly arrived Eritrean refugees in Switzerland: a cross-sectional study

OBJECTIVES

Our study aimed at determining the prevalence of selected infectious diseases among recently arrived Eritrean refugees in Switzerland.

METHODS

In this cross-sectional study, asymptomatic Eritrean migrants aged ≥16 years who arrived <24 months ago were recruited at refugee centres in Switzerland. Infectious disease screening included serology for HIV, hepatitis B and C, syphilis and schistosomiasis, polymerase chain reaction (PCR) for malaria, stool microscopy for helminths and intestinal protozoa and circulating cathodic antigen (CCA) testing in urine for schistosomiasis.

RESULTS

Among 107 participating Eritrean refugees, point-of-care CCA urine test for Schistosoma mansoni was positive in 43 patients (40.2%; 95% CI 31.9-49.5). Stool microscopy detected eggs of S. mansoni in 23 (21.5%; 95% CI 13.7-29.3), Hymenolepis nana in 11 (10.3%; 95% CI 4.5-16.0), and cysts of Giardia intestinalis in 7 participants (6.5%: 95% CI 1.9-11.2). Two tested positive for hepatitis B (1.9%; 95% CI 0.0-4.4) and one for syphilis (0.9%; 95% CI 0.0-2.8), none tested positive for HIV or hepatitis C. Malaria PCR was positive in six participants (5.6%; 95% CI: 1.2-9.9).

CONCLUSIONS

Given the high prevalence of S. mansoni infection and potentially severe long-term sequelae of untreated schistosomiasis, routine screening for schistosomiasis in refugees from Schistosoma-endemic regions should be recommended.

The use of circulating cathodic antigen rapid test and serology for diagnosis of active Schistosoma mansoni infection in migrants in Italy, a non-endemic country: a cross sectional study

Diagnosis of schistosomiasis in migrants coming from endemic areas can be difficult, especially in asymptomatic subjects. Light-intensity disease, in fact, may be missed due to the low sensitivity of the stool microscopy and serologic testing cannot distinguish between a resolved infection and an active infection in patients who have been infected and treated in the past, because specific antibodies can persist despite cure. We describe a cross-sectional study conducted on 82 migrants tested for Schistosoma mansoni on single blood (anti-schistosome antibodies, total IgE) and urine [point-of-care (POC) circulating-cathodic-antigen (CCA) test] samples. A positive POC-CCA test (active infection) resulted in two untreated patients with a positive serology while all patients (n = 66) with a past infection showed a negative POC-CCA test. POC-CCA urine test in combination with serology may be helpful in rapidly differentiate active from past S. mansoni infection in migrants coming from endemic areas.

Accuracy of parasitological and immunological tests for the screening of human schistosomiasis in immigrants and refugees from African countries: An approach with Latent Class Analysis

Background

Schistosomiasis is a neglected infection affecting millions of people, mostly living in sub-Saharan Africa. Morbidity and mortality due to chronic infection are relevant, although schistosomiasis is often clinically silent. Different diagnostic tests have been implemented in order to improve screening and diagnosis, that traditionally rely on parasitological tests with low sensitivity. Aim of this study was to evaluate the accuracy of different tests for the screening of schistosomiasis in African migrants, in a non endemic setting.

Methodology/Principal findings

A retrospective study was conducted on 373 patients screened at the Centre for Tropical Diseases (CTD) in Negrar, Verona, Italy. Biological samples were tested with: stool/urine microscopy, Circulating Cathodic Antigen (CCA) dipstick test, ELISA, Western blot, immune-chromatographic test (ICT). Test accuracy and predictive values of the immunological tests were assessed primarily on the basis of the results of microscopy (primary reference standard): ICT and WB resulted the test with highest sensitivity (94% and 92%, respectively), with a high NPV (98%). CCA showed the highest specificity (93%), but low sensitivity (48%). The analysis was conducted also using a composite reference standard, CRS (patients classified as infected in case of positive microscopy and/or at least 2 concordant positive immunological tests) and Latent Class Analysis (LCA). The latter two models demonstrated excellent agreement (Cohen’s kappa: 0.92) for the classification of the results. In fact, they both confirmed ICT as the test with the highest sensitivity (96%) and NPV (97%), moreover PPV was reasonably good (78% and 72% according to CRS and LCA, respectively). ELISA resulted the most specific immunological test (over 99%). The ICT appears to be a suitable screening test, even when used alone.

Conclusions

The rapid test ICT was the most sensitive test, with the potential of being used as a single screening test for African migrants.

Schistosomiasis is probably the most important of the neglected tropical diseases (NTD) caused by helminthes (worms). It is acquired bathing in freshwater in endemic areas. The life cycle is complex and involves freshwater snails. Schistosomiasis, caused by Schistosoma mansoni, S. haematobium and less frequently by other species, affects more than 200 million people, mostly in Africa, and may chronically cause irreversible damage of the liver (S. mansoni) or of the kidneys and the urinary tract, including cancer of the bladder (S. haematobium). As in chronic infections eggs of both species are often missed by microscopy of faeces and urine, with this retrospective study we evaluate the accuracy of different, alternative diagnostic tests, for the screening of schistosomiasis in African migrants and asylum seekers, of whom many thousands reach the Italian coast every year proceding from the most endemic areas. The most interesting finding of our study is that a rapid diagnostic test for antibody detection in blood, easy to use as a point-of-care tool, resulted the most sensitive of the five tests evaluated, and thus is very promising as a screening tool even when used without any additional test.

Validation of a Point-of-Care Circulating Cathodic Antigen Urine Cassette Test for Schistosoma mansoni Diagnosis in the Sahel, and Potential Cross-Reaction in Pregnancy

On the shores of Lake Chad, schistosomiasis among mobile pastoralists was investigated in a field laboratory. Point-of-care circulating cathodic antigen (POC-CCA) cassette test, reagent strip, and filtration were conducted on urine samples. Fresh stool samples were subjected to the Kato-Katz technique, and fixed samples were examined with an ether-concentration method at a reference laboratory. POC-CCA urine cassette tests revealed a Schistosoma mansoni prevalence of 6.9%, compared with only 0.5% by stool microscopy. Three pregnant women with otherwise negative urine and stool testing had positive POC-CCA. This observation raises concern of cross-reactivity in pregnancy. Hence, two pregnant women in Switzerland with no history of schistosomiasis were subjected to POC-CCA and one tested positive. Our data suggest that POC-CCA can be performed under extreme Sahelian conditions (e.g., temperatures > 40°C), and it is more sensitive than stool microscopy for S. mansoni diagnosis. However, potential cross-reactivity in pregnancy needs further investigation.