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In this work, we synthesized a novel hyperbranched Au plasmonic blackbody (AuPB) and applied it as a signal amplification label in immunochromatographic test strip (ICTS) sensor for the sensitive detection of aflatoxin B1 (AFB1) in maize. AuPB were characterized with high color signal intensity, superior colloidal stability, and excellent biocompatibility benefiting from the hyperbranched structure and the dense polydopamine layer on surface, which contributes to improving the sensitivity and robustness of competitive ICTS sensor. Under the optimized conditions, the half inhibition concentration and the detection limit of our AuPB-enhanced ICTS (AuPB-ICTS) sensor were 0.087 and 0.016 ng/mL, which are 3.9- and 5.4-fold lower than those of traditional ICTS sensor based on 35-nm gold nanospheres as signal reporters. The average recoveries for the intra- and inter-assay ranged from 92.5 to 119.5%, with the coefficient of variation of 3.29–10.28%. Moreover, the reliability and practicability of this method were validated by the well-established ultra-performance liquid chromatography method via simultaneously measuring fifteen naturally contaminated maize samples. In summary, the developed AuPB-ICTS sensor can serve as an alternative rapid diagnostic method to allow the sensitive and reliable screening of AFB1 in maize.

Clostridioides difficile infection is a public health problem because of it is easily spread; with harmful consequences, it is essential to reduce hospital costs and prevent its dissemination by having a precise diagnosis. The gold standard for its diagnosis is polymerase chain reaction (PCR); however, the technique is not available for all laboratories due to the high cost. New approaches using non-molecular tests to detect C. difficile and toxin A/B production has been proposed to improve cost benefits. The objective of this study is to compare molecular methods (PCR) and rapid methods (immunochromatographic test and enzymatic immunoassay). A series of tests comprising these diagnostic techniques was performed with 50 patients with a clinical diagnosis for Clostridioides difficile on GeneXpert® devices test; a calculation of the sensitivity was executed, followed by a comparison of the efficiency of all techniques. Greater sensitivity was observed in the PCR-based methods (BD MAX™ and BioFire FilmArray®) and the GDH-based assays (RIDASCREEN® and Alere Techlab®). The proposed algorithm represents minor monetary disadvantages but a significant temporal optimization of 10%. Future studies concerning both positive and negative results could be advantageous because of the possibility of calculating more method concordance indexes, such as the specificity and Kappa index, in addition to being able to indicate a monetary profit if the proposed algorithm was applied due to the nonproceeding PCR cases.

A more rapid and less complicated test is required in clinical settings to diagnose pertussis. We need to detect Bordetella pertussis, which mainly causes pertussis, as early as possible, because pertussis is more likely to become severe in infants, and people around them can easily become the source of infection due to its strong infectivity. Nevertheless, methods that can detect B. pertussis rapidly and efficiently are lacking. Therefore, we developed a new immunochromatographic antigen kit (ICkit) for the early diagnosis of pertussis. The ICkit detects B. pertussis antigens in a nasopharyngeal swab without equipment and provides the result in about 15 min with a simple procedure. Additionally, a prospective study to evaluate the ICkit was conducted in 11 medical institutions, involving 195 cases with suspected pertussis. The sensitivity and specificity of the ICkit were 86.4% (19/22) and 97.1% (168/173), respectively, compared with the real-time polymerase chain reaction (rPCR). The ICkit detected the antigen in both children and adults. Furthermore, the ICkit detected the antigen until the 25th day from the onset of cough, when rPCR detected the antigen. Thus, the ICkit demonstrated a high correlation with rPCR and would help diagnose pertussis more rapidly and efficiently.

A new approach to a multiplexed immunochromatographic system for rapid diagnosis of acute heart failure that included the use of colloidal quantum dots as labels was developed. The analysis was based on separation of analytes into bands and the use of biomarkers with various properties in the mixture being analyzed. The ability to use quantum dots synthesized in two different solutions for qualitative and quantitative analysis was demonstrated. The developed approach optimized the analytical capabilities of rapid diagnosis and increased its effectiveness and availability.

Fascioliasis, a food- and water-borne trematodiasis, has been identified as a public health threat by the World Health Organization, with millions of people estimated to be infected or at risk of infection worldwide. We developed an immunochromatographic test (ICT) as a point-of-care (POC) tool for the rapid serodiagnosis of human fascioliasis caused by Fasciola gigantica and evaluated their diagnostic ability. Two tests were developed using antigens from adult F. gigantica excretory-secretory (ES) product and recombinant F. gigantica cathepsin L (rFgCL). Sera from 12 patients with parasitologically proven fascioliasis caused by F. gigantica, 18 with clinically suspected fascioliasis, 65 with other parasitic infections, and 30 healthy controls were used. Using a cutoff of > 0.5 for antibody detection, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the ES-based ICT method were 100%, 98.9% 96.8%, 100%, and 99.2%, respectively, and those of the rFgCL-based ICT method were 86.7%, 93.7%, 81.3%, 95.7%, and 92.0%, respectively. The concordance between the two methods was 91.2%. Tests using F. gigantica ES and rFgCL antigens can be employed quickly and easily as POC diagnostic tools. They can be used to support the clinical diagnosis of human fascioliasis gigantica and in large-scale surveys in endemic areas throughout tropical regions without necessitating additional facilities or ancillary supplies.

Detection of Legionella pneumophila serogroup 1 urinary antigens is the most widely used technique for the diagnosis of Legionnaires' disease (LD). The aim of this study was to evaluate the performance of the Legionella K-set® immunochromatographic test, in comparison with the BinaxNOW® Legionella urinary antigen card (UAC) on concentrated urine samples (US). A total of 250 concentrated US including 200 prospective US sent to the laboratory for urinary antigens' testing and 50 frozen US from patients with confirmed LD were tested. Positive US were retested after boiling (5 min, 100 °C). Each US leading to discordant results between the two tests was further tested using Binax™ Legionella EIA. Then, 10 additional positive non-concentrated US were tested using both tests. On concentrated US, Legionella K-set® test showed concordant results with that of BinaxNOW® Legionella. All negative US with BinaxNOW® were negative with Legionella K-set® test. For the 50 frozen US, all were positive with BinaxNOW® and 49 were positive with Legionella K-set®, all confirmed after boiling except 3 US which led to uninterpretable results with Legionella K-set®, due to a migration defect. Three of the 10 additional positive non-concentrated US were found negative with Legionella K-set® and only 1 US remained negative after concentration. All these positive non-concentrated US were positive with BinaxNOW® Legionella. The performance of the Legionella K-set® test is comparable to that of BinaxNOW® Legionella UAC, if performed on concentrated US.

Human strongyloidiasis is an important gastrointestinal disease with an estimated 30 to 100 million people infected. Prevalence is generally underestimated since many infections are asymptomatic, and traditional diagnostic tests based on parasitological examination of stool samples are not adequately sensitive. Serological tests are useful and supportive but are still only available in a reference research setting. We made an immunochromatographic test (ICT) kit for rapid serodiagnosis of human strongyloidiasis. The antigen used in the ICT kit was extracted from larvae of Strongyloides stercoralis. Diagnostic efficacy of the kit was evaluated using human serum samples from strongyloidiasis patients, healthy persons, and those with other parasitoses. When using a cutoff level of 0.5 or above, the diagnostic sensitivity, specificity, and positive and negative predictive values at the prevalence of infection of 34.4%, were 93.3%, 83.7%, 76.7%, and 95.6%, respectively. This ICT kit is easy to use at the point-of-care and a result can be obtained in 15 min. Sophisticated instruments and highly trained staff are not required. It can be used in several diagnostic and public-health settings, e.g., prevalence surveys in endemic areas, confirmation and monitoring of cure post-treatment, diagnosis and screening of infected but asymptomatic individuals, and populations “at risk” for hyperinfection syndrome or disseminated strongyloidiasis if they are given immunosuppressive treatment for other conditions.

Histamine, a biogenic amine, is abundant in fermented foods and beverages, notably wine. A high intake of this monoamine may produce adverse reactions in humans, which may be severe in individuals with a reduced capacity to catabolise extrinsic histamine. Thus, control of histamine concentration during wine production and before distribution is advisable. Simple, rapid, point-of-use bioanalytical platforms are needed because traditional methods for the detection and quantification of histamine are expensive and time-consuming. This work applies the lateral flow immunoassay technique to histamine detection. Superparamagnetic particle labels, and an inductive sensor designed to read the test line in the immunoassay, enable magnetic quantification of the molecule. The system is calibrated with histamine standards in the interval of interest for wine production. A commercial optical strip reader is used for comparison measurements. The lateral flow system has a limit of detection of 1.2 and 1.5 mg/L for the inductive and optical readers, respectively. The capability of the inductive system for histamine quantification is demonstrated for wine samples at different processing points (at the end of alcoholic fermentation, at the end of malolactic fermentation, in freshly bottled wine, and in reserve wine). The results are validated by ultra-high-performance liquid chromatography. [Figure not available: see fulltext.]., This work was financially supported by the Spanish Ministry of Economy and Competitiveness under projects MAT2017-84959-C2-1-R, MAT2016-81955-REDT, and AGL2016-78708-R; the Council of Gijón-IUTA under grant SV-18-GIJON-1-27; and the Principality of Asturias under project IDI/2018/000185.

Scrub typhus is a mite-borne, acute febrile illness caused by the bacterium Orientia tsutsugamushi. It is a re-emerging infectious disease of the tsutsugamushi triangle. Scrub typhus is transmitted through bites of contaminated chiggers (larval stage). Diagnosis of scrub typhus is challenging as its symptoms mimic with other acute febrile illnesses. Several methods are effectual for diagnosis of scrub typhus that includes enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA), immunochromatographic test (ICT), Weil–Felix, polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP). Weil–Felix test was initially used for the diagnosis of scrub typhus in underdeveloped countries but not preferred due to a lack of both specificity and sensitivity. Other immuno-based methods like IFA and ELISA are most outrank for detection of scrub typhus due to their higher sensitivity and specificity, but not vigorous to lay bare the infection at early stages and need the convalescent sampling for verification of positive samples. On another deed, PCR based methods becoming acceptable over era due to its dexterity of early-stage diagnosis with higher specificity and sensitivity but lack its applicability in circumstances of scrub typhus due to the variegated genetic makeup of Orientia tsutsugamushi among its serotypes. The present review focused on various detection methods along with their advantages and disadvantages used in the diagnosis of scrub typhus. A comparison between available methods of diagnosis with challenges in the detection of scrub typhus is also summarized.

Screening of toxoplasmosis in cancer patients is mandatory especially before starting treatment to guard against life-threatening disseminated disease. Diagnosis of toxoplasmosis rely mainly on serology. The most widely used method for detection of anti-Toxoplasma gondii (T. gondii) antibodies is the enzyme linked immunosorbent assay (ELISA), being available and reliable. Immunochromatographic tests (ICT) attracted a lot of attention recently being one of the high quality, rapid and easy to perform tests. Available data comparing the performance of ICT versus ELISA techniques have yielded inconsistent results and none compared their performance among the immunocompromised cancer patients. Therefore, we designed this study to compare the performance of a new ICT (the OnSite Toxo IgG/IgM Combo Rapid test) and ELISA techniques for the detection of anti-T. gondii antibody as a tool for screening for toxoplasmosis among cancer patients in Cairo-Egypt. Among 180 cancer patients, a total of 110 patients (61.1%) were positive for anti-T. gondii antibodies by one or both methods. Agreement between both methods was found in 78.8% of the samples. By using ELISA technique as a gold standard test for the detection of anti-T. gondii antibodies, our results showed 87.5% specificity and 74% sensitivity of ICT technique. Moreover, our results proved that ICT is more sensitive in detecting lower level of antibodies than ELISA, that makes it preferable as a screening test for the immunocompromised patients.

The rapid detection of carbapenemase-producing Gram-negative bacteria is indispensable to optimize treatment and avoid the further spread of these organisms. While phenotypic tests are time-consuming and PCR is expensive and not available in many routine laboratories, immunochromatographic tests (ICT) can provide rapid results at moderate cost. The aim of this study was to determine the performance of the new ICT RESIST-4 O.K.N.V. K-SeT (Coris BioConcept, Gembloux, Belgium) which can detect the four most prevalent carbapenemases: OXA-48-like, KPC, NDM, and VIM. Additionally, we analyzed the impact of different culture conditions on the sensitivity. The new ICT was challenged with 169 carbapenem-resistant isolates. Of these, 125 were carbapenemase producers: 43 OXA-48-like, 15 KPC, 29 NDM, and 43 VIM. The ICT correctly detected 129 of the 130 carbapenemases resulting in a sensitivity of 99.2% and specificity of 100% when tested from Mueller-Hinton agar (MHA). The sensitivity of the assay increased to 100% when performed from zinc-supplemented MHA and sheep blood agar (SBA) or when the inoculum was harvested from the inhibition zone of an ertapenem disk. All carbapenemase-negative carbapenem-resistant bacteria tested negative and no cross-reaction was observed. The new ICT is an excellent test for rapid diagnostic of carbapenemase-producing Gram-negatives in the routine laboratory. It is easy to handle and provides rapid results with a high sensitivity. For best results, we recommend to obtain the inoculum from a medium with sufficient zinc or from the inhibition zone of an ertapenem disk.

The authors describe a multicolor immunochromatographic test strip format for simultaneous detection of Vibrio cholera O1 (Ogawa) and of the Clostridium botulinum toxin type A. Respective monoclonal antibodies were conjugated to CdTe quantum dots (QDs) with green and orange emission color. Activated dextran is used as a cross-linker. The CD labeled antibodies were then covered with denatured reduced BSA (dBSA-QD). Under illumination, the test gives lines with emission peaks at 540 nm and 570 nm, respectively. This lateral flow assay system can detect V. cholerae down to 1000 cfu·mL−1 levels, and C. botulinum toxin down to 0.8 ng·mL−1. The method allows assays to performed within 10 min without any sample pretreatment.

The authors describe an immunochromatographic test for the rapid detection of cardiac dysfunction by quantifying the cardiac markers troponin I (TnI), fatty acid binding protein (FABP), and C-reactive protein (CPR) in serum. The dynamics of the formation of the immuno-complexes between antibodies (labeled with gold nanoparticles) and analytes (biomarkers) during immunochromatography was studied, and requirements are specified in terms of membrane carriers and reaction medium that are necessary to detect these biomarkers with their varying intracellular localizations and physical and chemical properties. The test can be performed within 10 min and enables TnI to be determined in concentrations of ≥ 1.0 ng mL−1, FABP in concentrations of ≥ 3.8 ng mL−1, and CPR in concentrations of ≥ 600 ng mL−1. The results of the new test system correlated well with those obtained by ELISAs as used in cardiodiagnostics. It is emphasized here that simultaneous control of several myocardial biomarkers provides more information on the dynamics and development of the pathological process and enables more effective therapeutic decisions.

Nucleic acid lateral flow assays (NALFA) are often performed with gold nanoparticles. These are typically associated with ligand-labeled PCR amplicons via affinity interactions of adsorbed/conjugated proteins. Otherwise, they are conjugated to specific ssDNA sequences that hybridize to the target sequence. To avoid the need to generate ssDNA and to reduce the costs associated with primer labeling and antibody use, NALFA assays were developed that allow the direct detection of PCR amplicons using conjugates of a DNA binding protein with carbon nanoparticles (CNPs). The target gene encoding 16S ribosomal RNA of Escherichia coli was amplified by PCR using a single fluorophore-labeled forward primer and a reverse primer extended with the binding sequence of the bacteriophage lambda Cro repressor protein. Three different detection approaches were evaluated: (a) scCro/CNPs conjugate (black color), (b) HRP-scCro enzyme conjugate (red color), and (c) HRP-scCro/CNPs conjugate for dual color development. The limits of detection were between 6.9 and 10.4 ng of PCR product for all three approaches. These correspond to 3.0 to 4.5 × 103 CFU·mL−1. The single-step scCro/CNP approach proved to be the fastest one to perform and gave no false-positive signals. It also showed a broad dynamic range even though the signal intensities were lower compared to the enzyme-amplified tests. However, the latter ones produced some background signal. In our perception, the application of scCro in lateral flow assays to bind dsDNA appears to be an excellent alternative to the use of small tags that have to be chemically linked to synthetic primers. Finally, the approach is generic because any primer sequence can be extended with the specific scCro binding sequence. [Figure not available: see fulltext.].

Salbutamol (SAL), a kind of β-agonist which can enhance the lean meat-to-fat ratio, has been inhibited as an additive used in animal feeds for livestock production in many countries due to its harmful effect to the consumers. In this study, an ultrasensitive and specific competitive immunochromatographic test (ICT) integrated with surface-enhanced Raman scattering (SERS) for the detection of SAL was described. The immunoprobe was prepared by immobilizing polyclonal antibody against SAL on the surface of Au@Ag nanoparticles in which the Raman reporter (4-mercaptobenzoic acid, MBA) had been sandwiched. After ICT procedures, the specific SERS signals generated from MBA on the test line of the ICT strip were measured for the quantitative determination of SAL. The assay was completed in 15 min. The IC50 and the limit of detection (LOD) values of the assay for SAL were 0.028 ng mL−1 and 3.0 pg mL−1, respectively. There was no cross-reactivity (CR) of the assay with other three β-agonists (clenbuterol, phenylethanolamine A, and ractopamine), showing high specificity of the assay. Spiking experiments indicated that the average recoveries (n = 3) of SAL from swine feed, meat, and urine samples were in ranges of 98.4–105.2 % with the relative standard deviations (RSDs) of 1.7–7.8 %. The results demonstrated that the proposed ICT was a feasible method for ultrasensitive and specific detection SAL in swine feed, meat and urine samples, and could be extended for the detection of other target analytes.

ENR and OFL are the most consumed quinolones on livestock in China. In this work, we developed a rapid immunochromatographic lateral flow test strip for simultaneous detection of the residues of enrofloxacin and ofloxacin in chicken muscle and pork. We screened an anti-ENR and OFL monoclonal antibody. The IC50 of anti-ENR and anti-OFL were 6.67 and 7.13 ng/ml, respectively. The present immunochromatographic lateral flow test strip is a one-step assay and required much less professional personnel and experimental instruments. In the present study, the decision limit (CCα) of the test strip was calculated to be 0.089 ng/mL and detection capability (CCβ) was 0.217 ng/mL with the scanner. The limit of detection was estimated to be 10 ng/mL. According to parallel HPLC analysis with 47 blind samples, coincidence rate is 100 % when the contents of ENR and OFL were more than 10 ng/mL. Results indicated that the strip test we developed had good reliability, and the strip test gave neither false positive nor false negative results. It will provide results within 20 min without special equipment. Therefore, the test strip is very useful as a screening method for semi-quantitative or qualitative detection of enrofloxacin and ofloxacin in chicken muscle and pork.

A lateral-flow immunochromatographic assay (LFIA) using monoclonal antibody was developed for the rapid detection of ractopamine residues in swine urine. The assay procedure could be accomplished within 5 min, and the results of this qualitative one-step assay were evaluated visually according to whether test lines appeared or not. When applied to the swine urines, the detection limit and the half maximal inhibitory concentration (IC50) of the lateral-flow immunochromatographic test strip under an optical density scanner were calculated to be 0.1 ± 0.013 and 0.71 ± 0.056 ng/mL, respectively. The cut-off level was observed with the naked eye of 1 ng/mL for detection of ractopamine residue in swine urine. Parallel analysis of swine urine samples with ractopamine showed comparable results obtained from the LFIA and LC-MS/MS. Therefore, the described lateral-flow test strip can be used as a reliable, rapid and cost-effective on-site screening technique for the determination of ractopamine residues in swine urine.

Animal trypanosomosis is a disease that is distributed worldwide which results in huge economic losses due to reduced animal productivity. Endemic regions are often located in the countryside where laboratory diagnosis is costly or inaccessible. The establishment of simple, effective, and accurate field tests is therefore of great interest to the farming and veterinary sectors. Our study aimed to develop a simple, rapid, and sensitive immunochromatographic test (ICT) for animal trypanosomosis utilizing the recombinant tandem repeat antigen TeGM6-4r, which is conserved amongst salivarian trypanosome species. In the specificity analysis, TeGM6-4r/ICT detected all of Trypanosoma evansi-positive controls from experimentally infected water buffaloes. As expected, uninfected controls tested negative. All sera samples collected from Tanzanian and Ugandan cattle that were Trypanosoma congolense- and/or Trypanosoma vivax-positive by microscopic examination of the buffy coat were found to be positive by the newly developed TeGM6-4r/ICT, which was comparable to results from TeGM6-4r/ELISA (kappa coefficient [κ] = 0.78). TeGM6/ICT also showed substantial agreement with ELISA using Trypanosoma brucei brucei (κ = 0.64) and T. congolense (κ = 0.72) crude antigen, suggesting the high potential of TeGM6-4r/ICT as a field diagnostic test, both for research purposes and on-site diagnosis of animal trypanosomosis.

Identifying the biological source of a crime scene stain can be crucial for police investigations in many scenarios. Blood is one of the most common fluids found, and accurate differentiation between peripheral blood and menstrual fluid could provide valuable information regarding the issue of consent in sexual assault cases. For the detection of menstrual fluid, no easy-to-use presumptive test is available to date. Therefore, this study aimed to validate a simple immunochromatographic test for the indication of menstrual fluid, focusing on a D-dimer assay. The Clearview® rapid D-dimer test provides a diagnostic assay for the detection of fibrin degradation products. We validated the sensitivity and robustness of the assay using fresh and dried menstrual fluid samples, body fluid mixtures, diluted samples, and casework swabs. Cross reactivity was tested for saliva, semen, vaginal fluid, and blood. No false positive results were obtained; it was possible to successfully analyze mixtures, highly diluted samples, and casework swabs. The results of this study indicate that the D-dimer assay reliably detects menstrual fluid in forensic exhibits and is easy to implement into the current workflow of body fluid identification.

The operating principle of immunochromatographic test systems is considered. It is noted that with the use of such tests an immunoassay is implemented as a sandwich method in the form of a direct dependence of the luminescence of test stripes on the concentration of the test substance or as a competitive method with an inverse dependence. An experimental procedure of obtaining such dependences, which is necessary for the construction of calibration curves, is set forth. Exponential expressions for arriving at an analytic description of the associated curves are proposed; moreover, the coefficients in these expressions are determined by the method of least squares. An analysis of the error of the method of calibration curves that may be used to obtain quantitative results of the analysis is presented.

The primary aim of this study was to evaluate the frequency and seasonality of norovirus infection in hospitalized Polish children under 5 years of age, and a secondary aim was to compare the clinical severity of norovirus and rotavirus disease. The prospective surveillance study was carried out from July 2009 through June 2010. Stool samples from 242 children hospitalized due to acute viral gastroenteritis were tested for rotavirus group A and adenovirus with commercial immunochromatographic test and for norovirus with EIA assay. Single norovirus infection was found in 35/242 (14.5%) patients and in a further 5 (2.1%) children as co-infection with rotavirus. Overall, norovirus was detected in 16.5% of stool specimens. Norovirus infections tended to peak from October to November and again from February to March. In autumn months and in February, the proportion of norovirus gastroenteritis cases was equal or even surpassed those of rotavirus origin. Both norovirus and rotavirus infections most commonly affected children between 12 and 23 months of age. The low-grade or no fever was significantly more common in children infected with norovirus (94.3%) compared to rotavirus cases (52.9%). Overall, norovirus gastroenteritis was less severe than rotavirus disease with regard to 20-point severity scale (p

Background Dengue is an important mosquito-borne viral infection that affects millions of persons worldwide. Early diagnosis is necessary to effect appropriate management and decrease mortality. Immunochromatographic tests are advantageous in producing dengue test results within 30 min but these results should be sensitive and specific. In this study we evaluated the diagnostic performance of the SD BIOLINE Dengue DUO® rapid immunochromatographic test kit. A panel of 309 dengue and 30 non-dengue single serum samples characterized by using reference enzyme-linked immunosorbent assays (ELISAs) was used. These samples were received in the virology laboratory for routine testing during a dengue type 1 outbreak between October to December, 2012. Results The overall diagnostic sensitivities of the SD BIOLINE Dengue DUO® rapid testfor IgM, IgG and NSI were 49.3 % (95 % CI: 41.3-57.4), 39.1 % (95 % CI: 33.3-45.2) and 90 % (95 % CI: 82.1-94.7), respectively. The IgM and IgG detection rates were significantly lower than that of the NSI (p

Background: Accurate and early diagnosis of Visceral Leishmaniasis (VL) is a prerequisite for proper treatment and restricting disease propagation in enldemic foci. An rK39 antigen-based immunochromatographic test is now recommended for its diagnostic accuracy and operational feasibility at point of care. In endemic regions of Bangladesh, rK39 or rKE16 antigen-based Rapid Diagnostic Tests (RDTs) are routinely performed on whole blood for diagnosis of VL. However, manufacturer’s instructions require use of serum. Therefore, we wanted to assess whether the diagnostic accuracy of these RDTs is as good on whole blood as on serum. Methods: We evaluated and compared the sensitivity and specificity of five different commercially available RDTs on whole blood and on serum. We enrolled 30 VL patients, 35 endemic healthy controls and 30 Tuberculosis (TB) patients in our study from Mymensingh, a hyper-endemic region in Bangladesh. Results: The sensitivity of all RDTs ranged between 96.67 % (95 % CI: 82.72-99.44 %) and 100 % (95 % CI: 96.34-100 %). The specificity ranged between 93.85 % (95 % CI: 84.97-98.26 %) and 98.46 % (95 % CI: 91.69-99.74 %), except for the Onsite leishmania Ab (Rev B) kit which showed markedly lower specificity (31.25-58.46 %). There was no significant difference in sensitivity and specificity between blood and serum. The Cohen kappa index (k >0.97) indicated excellent agreement. Conclusions: We conclude from the study that the use of blood for RDT in lieu of serum is appropriate for diagnosis of VL in peripheral endemic regions provided the manufacturer recommendations are followed and the RDT is of good quality.

Background Malaria presents a considerable threat to public health. Histidine-rich protein 2 (HRP 2) is the major protein released into human blood upon infection by Plasmodium falciparum. In this study, we aimed to evaluate the immunogenicity of HRP 2 exon II and the efficacy of novel monoclonal antibodies (mAbs) against HRP 2 for Point-of-Care Test (POCT). Methods The recombinant protein was expressed in soluble form in E. coli and used to immunize mice for mAb production. Two IgG1 mAbs (1A5 and 1C10) with high affinity, specificity and sensitivity for both native and recombinant HRP 2 were selected after fusion of mouse spleen with myeloma cells. The affinity constant of 1A5 and 1C10 were 7.15 and 4.91 × 10-7 L/mol, respectively. Subsequently, an immunochromatograhic assay was used for screening of clinical samples in endemic regions of China and Myanmar. Results The immunochromatographic test retrospectively showed an overall sensitivity of 99.07%, and specificity of 100%. Sensitivity at parasite densities 2000 parasites/μL was 87.5, 98.7, and 100%, respectively. Conclusions These results suggest that HRP 2 exon II contains immunogenic sites similar to those of the native antigen and can be used for the development of mAbs suitable for malaria diagnosis in endemic communities.

Dengue fever is increasingly recognized in travelers returning from endemic areas with acute febrile illness; however, its true burden in nonendemic countries is unknown. Only few studies focus on clinical manifestations and serological findings in primarily nonimmune individuals.We analyzed the epidemiology, clinical manifestations and virological results in patients with imported acute dengue infection who presented at our travel clinic in Frankfurt am Main, Germany, between September 1998 and November 2000. An immunochromatographic test and an immunofluorescence assay were used for antibody testing.Dengue fever was confirmed in 13 patients, thus being the second commonest tropical infection after malaria in patients with fever and a travel history to a tropical country (18 cases per 1,000 patient visits per year). Most patients had only spent a short time abroad, either in South Central or South East Asia or in the Caribbean.The clinical features considered typical for dengue were not always present. Antibody assays were typically negative early in the course of disease, with seroconversion occurring only after cessation of clinical symptoms. A high index of suspicion is needed in these patients who often present without typical features of dengue and whose early antibody tests may be negative.

To test the diagnostic value of a rapid and simple immunochromatographic test (ICT) based on the detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) for post-mortem examination, blood samples from 30 consecutive corpses were analysed by ICT and Giemsa-stained blood films. Compared to microscopy, ICT had 100% sensitivity and 100% specificity even after a considerable time had passed between the presumed time of death and testing or after prolonged storage of whole blood samples. The ICT yielded positive results for four travellers who had returned from Kenya and died from Pl. falciparum malaria. The ICT might therefore serve as an additional tool for rapid malaria diagnosis, especially in non-endemic countries where experience with microscopic malaria detection is limited.

A rapid immunochromatographic dipstick test has become available for the qualitative detection of total anti-Leishmania immunoglobulins using the recombinant K39 antigen. To evaluate the test, 96 serum specimens from patients with a variety of tropical infections were tested. Fourteen of the specimens derived from patients with parasitologically confirmed kala-azar, and all were strongly positive for antibodies to Leishmania donovani complex using the immunofluorescence test. Although all 82 samples negative by the immunofluorescence test were confirmed as negative by the dipstick assay, only 10 (71.4%) of the 14 positive samples were reactive. These results indicate that the test in its current form lacks sufficient sensitivity to be recommended as a screening tool, but it might be useful for indicating further diagnostic procedures in a clinical setting.