IgM Enzyme-linked Immunosorbent Assay Research Articles

An enhanced immunochromatographic strip test using colloidal gold nanoparticle-labeled dual-type N proteins for detection of antibodies to PRRS virus.

Porcine reproductive and respiratory syndrome (PRRS) is recognized as one of the most important infectious diseases causing serious economic loss in the swine industry worldwide. Due to its increasing genetic diversity, a rapid and accurate diagnosis is critical for PRRS control. The immunochromatographic strip test (ICST) is a rapid and convenient type of immunoassay. In this study, an on-site immunochromatographic assay-based diagnostic method was developed for detection of PRRS virus (PRRSV)-specific antibodies. The method utilized colloidal gold nanoparticle-labeled dual-type nucleocapsid proteins encoded by open reading frame 7. We evaluated 991 field samples from pig farms and 66 serum samples from experimentally PRRSV-inoculated pigs. Based on true PRRSV-specific antibody-positive or -negative sera determined by immunofluorescence assay and IgM enzyme-linked immunosorbent assay (ELISA), the specificity and sensitivity of the ICST were 97.5% and 91.1%, respectively, similar to those of a commercial ELISA (IDEXX PRRS X3 Ab). More importantly, the ICST was completed within 15 min and could detect the PRRSV-specific antibody at an earlier stage of infection (3–7 days) than that of ELISA (7+ days). The results demonstrate that the developed ICST has great potential as an on-farm diagnostic method, providing excellent diagnostic performance in a quick and convenient manner.

Evaluation of a Commercial Enzyme-Linked Immunosorbent Assay Kit for Detection of IgM Antibody against Leptospira in Human Sera for Patients admitted in Malaysian Hospitals

Leptospirosis is an infectious zoonotic disease caused by corkscrew shaped of pathogenic Leptospira spp. Early diagnosis is important as the disease can be treated with antibiotic to prevent complications. The gold standard of leptospirosis diagnosis is microscopic agglutination test (MAT). However, the test is laborious and time consuming. This study aimed to evaluate whether a commercial ELISA (enzyme-linked immunosorbent assay) kit by Virion- Serion can demonstrate antibody against leptospires for accurate and rapid screening for leptospirosis. A total of 212 serum samples were tested with Virion-Serion Classic ELISA IgM, which was earlier collected from patient with clinical manifestation suggestive of leptospirosis in Malaysia and confirmed with MAT. The results were analyzed into two categories. In the first category all samples that were positive with MAT but detected as intermediate by the ELISA were not included. In the second category, all sample that positive with MAT but detected as intermediate were included. When the intermediate results were excluded, the clinical sensitivity was 73% and clinical specificity was 94%. When the intermediate results were included, the clinical sensitivity and specificity were 75% and 85% respectively. From this finding we can conclude that Virion-Serion ELISA IgM Classic kit have a reasonably appropriate performance and can be used for screening and diagnosis for leptospirosis in acute febrile illness however it should be confirmed later with the gold standard serological test which is MAT.

First confirmed case of Powassan neuroinvasive disease in Rhode Island

The Powassan Virus is the arthropod-borne vector responsible for Powassan neuroinvasive disease. The virus was first isolated in 1958 and has been responsible for approximately 100 cases of neuroinvasive disease. Rates of infection have been on the rise over the past decade with numerous states reporting their first confirmed case; New Jersey, New Hampshire and Connecticut all reported their first case within the last five years. We present here the first confirmed case of Powassan neuroinvasive disease in the nearby state of Rhode Island. A previously healthy 81-year-old female with known tick exposure presented with fever, altered sensorium, seizures and focal neurological deficits. After an extensive work-up that was largely unrevealing Powassan encephalitis was suspected. The diagnosis was confirmed with serological testing consisting of Powassan IgM enzyme-linked immunosorbent assay and Powassan plaque reduction neutralization testing. The case study provides evidence for the increasing spread of Powassan neuroinvasive disease and reinforces the importance of requesting focused testing for Powassan Virus in patients from an endemic area with a clinically compatible syndrome.

Diagnostic value of serum IgM enzyme-linked immunosorbent assays in polymerase chain reaction-positive Mycoplasma pneumonia in children

Diagnostic value of serum IgM enzyme-linked immunosorbent assays in polymerase chain reaction-positive Mycoplasma pneumonia in children

Comparison of six commercial tick-borne encephalitis IgM and IgG ELISA kits and the molecular characterization of their antigenic design

Tick-borne encephalitis virus (TBEV) diagnosis is mainly based on the detection of viral-specific antibodies in serum. Several commercial assays are available, but published data on their performance remain unclear. We assessed six IgM and six IgG commercial enzyme-linked immunosorbent assay (ELISA) kits (ELISA-1 through ELISA-6) using 94 samples, including precharacterized TBEV-positive samples (n=50) and -negative samples (n=44). The six manufacturers showed satisfactory sensitivity and specificity and high overall agreement for both IgM and IgG. Three manufacturers showed better reproducibility and were the most sensitive (100%) and specific (95.5–98.1%) for both IgM and IgG. Two of them were also in agreement with the clinical interpretation in more than 90% of the cases. All the assays use inactivated virus as antigen, with strains showing approximately 94% homology at the amino acid level. The antigenic format of the assays was discussed to further improve this TBEV diagnostic tool.

Antidesmoglein 1 and 3 antibodies in healthy subjects of a population in the Peruvian high amazon.

The objective of this study was to determine the presence of anti-Dsg1 and Dsg3 antibodies in healthy subjects of the high Peruvian Amazon (Tuemal, Rodriguez de Mendoza province, department of Amazonas) to establish the theoretical presence of environmental factors or triggers in the area. Cross-sectional study. The study population included persons of any age or gender, clinically healthy, who were evaluated by a dermatologist to confirm the absence of blistering diseases. Blood samples were analyzed by indirect immunofluorescence (IIF), immunoprecipitation (IP), anti-Dsg1 IgM antibody (Ab) enzyme-linked immunosorbent assay (ELISA), as well as anti-Dsg1 and anti-Dsg3 IgG Ab ELISA. Participants included 21 healthy subjects comprised of 61.9% males and 38.1% females; 47.6% had a positive anti-Dsg1 Ab ELISA for total IgG (or any subclasses). IIF detected antibodies against intercellular spaces in one subject. Anti-Dsg1 Ab IP was mildly positive in 33.3% of the subjects. Anti-Dsg1 IgG subclasses found positive were: IgG1 (19.0%), IgG2 (33.3%), and IgG3 (28.6%); none of the samples were positive for anti-Dsg1 Ab IgM ELISA, and 23.8% of the subjects were positive for anti-Dsg3 Ab ELISA. The age distribution was similar for subjects positive for anti-Dsg1 and anti-Dsg3 Ab ELISA, with higher frequencies found among the 20-29 and 40-49year-old age groups. A fraction of healthy subjects of the high Peruvian Amazon developed anti-Dsg1 and anti-Dsg3 antibodies, demonstrating the possible presence of environmental factors for endemic pemphigus (EP) at a higher altitude than previously described.

Missed opportunities for the diagnosis of Brucella infection among slaughterhouse workers at the Kumasi Abattoir, Ghana

Brucellosis is a zoonotic disease in humans with its public health importance. Laboratory diagnostic methods targeting brucellosis are not performed in hospital settings across Ghana. Very little is known about the comparative diagnostic abilities of the various tests available presently. The aim of this study therefore was to evaluate and compare diagnostic performances of Rose Bengal Plate Test (RBPT), Enzyme Linked Immunosorbent Assay (ELISA) and Polymerase Chain Reaction (PCR) employed in diagnosing Brucella infection.Two hundred and twenty Abattoir workers were randomly selected in Kumasi, Ghana. Blood samples were collected, serum extracted and tested for the presence of anti-Brucella antibodies and compared among three different techniques, using ELISA, RBPT and PCR.From the 220 participants tested for antibodies against Brucella spp., 3 (1.4%), 4 (1.8%) and 21 (9.6%) were positive for Rose Bengal Plate test, anti-Brucella ELISA IgM and anti-Brucella ELISA IgG respectively. A total of 98 (44.5%) participants tested positive by PCR. The sensitivity, specificity, positive predictive value, negative predictive values and Kappa value for Rose Bengal in comparison with PCR were 66.7%, 55.8%, 2.0%, 100% and 0.013 respectively while that for ELISA IgG in comparison with PCR were 85.7%, 71.3%, 18.4%, 98.5% and 0.212 respectively.PCR yielded the highest sensitivity and specificity among the three diagnostic methods in this study and should be considered for use at strategic reference laboratories to augment existing routine serological tests for brucella performed in laboratories in Ghana.

Poor performance of two rapid immunochromatographic assays for anti-Japanese encephalitis virus immunoglobulin M detection in cerebrospinal fluid and serum from patients with suspected Japanese encephalitis virus infection in Laos.

Background Japanese encephalitis virus (JEV) is a leading identified cause of encephalitis in Asia, often occurring in rural areas with poor access to laboratory diagnostics. We evaluated two rapid diagnostic tests (RDTs) for anti-JEV immunoglobulin M (IgM) detection.MethodsConsecutive cerebrospinal fluid and serum from 388 patients (704 samples) with suspected JEV infections admitted to six hospitals in Laos were tested with one of two SD-Bioline anti-JEV IgM RDTs and the World Health Organization standard anti-JEV IgM enzyme-linked immunosorbent assay (ELISA; Panbio Japanese Encephalitis–Dengue IgM Combo ELISA.Results and ConclusionsThe performance of both RDTs showed strikingly low sensitivity in comparison to anti-JEV IgM antibody capture ELISA (2.1–51.4%), suggesting low sensitivity of the RDTs. We highlight the fundamental prerequisite to validate RDTs prior to use to ensure that they meet standards for testing.

Dengue virus infections among blood donors in Guangxi of China, 2013-2014.

An unexpected, large dengue outbreak, spreading to 20 cities of Guangdong province, occurred in July 2014. Considering the overwhelming influence of this seasonal epidemic, whether this dengue virus outbreak has an significant impact on the blood donors of the ajacent areas in Guangdong requires at least a preliminary investigation. Liuzhou City of Guangxi was chosen as a good representative of the neighbouring geographical location of the dengue virus (DENV) outbreak areas in this research. We therefore investigated qualified blood donations during potential dengue epidemic seasons and thus provided critical information for public health and donation policy making. A total of 1685 donations from 2013 to 2014 were collected at the Guangxi blood centre. Anti-DENV testing was performed using enzyme-linked immunosorbent assay (ELISA). Dengue IgG indirect ELISA and Dengue IgM capture ELISA were used to detect anti-DENV IgM and IgG. Repeat-reactive samples with ELISA test and 1685 donations with 421 pools were screened for dengue RNA by reverse transcription real-time quantitative polymerase chain reaction (RT-qPCR) using an in-house assay. There was a total of 13 seropositive donors, including 6 IgM seropositive and 7 IgG seropositive. The total seropositive rate was 0·78%, with IgM 0·36% and IgG 0·42%. Seropositive donors were identified mostly between April and November, with a peak in November. .All samples in reactive pools and individual seropositive samples were negative in the follow-up RT-PCR test. Our results suggested that the Guangdong dengue outbreak had limited impact on blood safety in surrounding areas under our current testing system.

Chikungunya fever outbreak identified in North Bali, Indonesia.

Chikungunya virus (CHIKV) infections have been reported sporadically within the last 5 years in several areas of Indonesia including Bali. Most of the reports, however, have lacked laboratory confirmation. A recent fever outbreak in a village in the North Bali area was investigated using extensive viral diagnostic testing including both molecular and serological approaches. Ten out of 15 acute febrile illness samples were confirmed to have CHIKV infection by real-time PCR or CHIKV-specific IgM enzyme-linked immunosorbent assay (ELISA). The outbreak strain belonged to the Asian genotype with highest homology to other CHIKV strains currently circulating in Indonesia. The results are of public health concern particularly because Bali is a popular tourist destination in Indonesia and thereby the potential to spread the virus to non-endemic areas is high. KY885022, KY885023, KY885024, KY885025, KY885026, KY885027.

An ELISA assay using a combination of recombinant proteins from multiple strains of Orientia tsutsugamushi offers an accurate diagnosis for scrub typhus

BackgroundScrub typhus (ST) is a disease caused by an obligate intracellular bacterium, Orientia tsutsugamushi, an organism that requires a BSL3 laboratory for propagation. The disease is hallmarked by an eschar at the site of the chigger bite, followed by the development of fever, malaise, myalgia, anorexia, and papulomacular rash. Indirect immunofluorescent assay (IFA) is the gold standard for scrub typhus diagnosis, however, the subjectivity of the assay, the need for a specialized laboratory and instruments has limited the wide use of the test in resource limited areas.MethodsA recombinant-protein based enzyme linked immunosorbent assay (ELISA) using the most abundant and immunodominant protein for the detection of Orientia specific antibodies in serum has been developed. The performance of the assay was evaluated using prospectively collected acute sera from 248 randomly selected patients in Thailand. The ELISA assay was evaluated using two different cutoff values.ResultsThe receiver operating characteristic (ROC) curve generated cutoff values gave slightly better consistency with diagnosis of ST than those cutoff values established by averaging ELISA optical density of known negatives at 99% confidence interval. Both cutoff values provided similar statistical parameters when compared with the diagnosis of ST, indicating the validity of both calculations to derive cutoff values. These results suggest that both IgG and IgM ELISA performed well to accurately diagnose scrub typhus cases in endemic areas using only acute serum samples.ConclusionsWe have successfully developed an ELISA assay for the detection of Orientia-specific antibodies in serum that could provide effective screening of acute sera under clinical setup and it is also a useful assay to estimate seroprevalence in various endemic areas.

Improving the Diagnosis of Scrub Typhus by Combining groEL Based Polymerase Chain Reaction and IgM ELISA.

Scrub typhus, an acute febrile illness, caused by Orientia tsutsugamushi, is an important cause of pyrexia of unknown origin in regions of endemicity. This disease is mostly underdiagnosed or misdiagnosed, the reasons for this being a combination of factors which include clinical manifestations that can mimic other infections, lack of easy and reliable diagnostic methods and variation among strains in endemic areas. Hence, easy and reliable methods of diagnosis will contribute to rapid identification and treatment of the infection. The aim of the study was to compare four different methods of detection of scrub typhus and to identify one single test or a combination of tests detecting maximum number of cases. One hundred and forty-five suspected scrub typhus cases were included in this study. Duration of fever and presence of eschar in each patient was noted down. Enzyme-Linked Immunosorbent Assay (ELISA) to detect Immunoglobulin M (IgM) antibodies and Polymerase Chain Reaction (PCR) to detect three genes of Orientia, namely, 56 kDa, 16S rRNA, and groEL were done on these samples. The results of each test were analyzed to identify the test picking up maximum number of positive samples. Statistical analysis was performed using Chi-square test. The level of significance was set at p<0.05. These tests showed that IgM ELISA (93%) and PCR (68%) picked up maximum number of positives. Statistical analysis performed using Chi-square test between the diagnostic assays showed that the p - value <0.001 was significant for IgM ELISA. Among the molecular markers, p-value was significant (<0.001) for groEL PCR. Further analysis of eschar positivity and duration of fever also showed that groEL PCR could detect DNA of the bacterium even in cases with 10 days of fever and this PCR was the best among the molecular markers used to detect the infection. This study suggests that IgM detection by ELISA and conventional groEL PCR, either in combination or alone, depending on the duration of fever, would enhance the diagnosis of scrub typhus.

Recombinant LipL32 Protein Developed Using a Synthetic Gene Detects Leptospira-specific Antibodies in Human Serum Samples.

Synthetic biology is emerging as a viable alternative for the production of recombinant antigens for diagnostic applications. It offers a safe alternative for the synthesis of antigenic principles derived from organisms that pose a high biological risk. Here, we describe an enzyme-linked immunosorbent assay (ELISA) using the synthetic recombinant LipL32 (rLipL32) protein expressed in Escherichia coli for the detection of Leptospira-specific antibodies in human serum samples. The rLipL32-based ELISA was compared with a microscopic agglutination test (MAT), which is currently used as the gold standard for the diagnosis of leptospirosis. Our results showed that all the MAT-positive serum samples were positive for Leptospira-specific IgG in an ELISA, while 65% (n = 13) of these samples were also positive for Leptospira-specific IgM. In the MAT-negative serum samples, 80% and 55% of the samples were detected as negative by an ELISA for Leptospira-specific IgM and IgG, respectively. An ELISA using the synthetic rLipL32 antigen was able to distinguish Leptospira-specific IgM (sensitivity 65% and specificity 80%) and IgG (sensitivity 100% and specificity 55%) in human serum samples and has the potential to serve as a rapid diagnostic test for leptospirosis.

Renal Manifestation in Scrub Typhus during a Major Outbreak in Central Nepal.

Renal involvement and acute kidney injury (AKI) are common clinical manifestations seen in scrub typhus, a vector-borne tropical disease. There are no data on renal manifestation in scrub typhus in Nepal. We conducted a prospective study to analyze the incidence, urinary abnormalities, course, severity, outcome, and the predictors of AKI in patients with scrub typhus during a major outbreak in Central Nepal. Total 1398 patients admitted with acute febrile illness were subjected for Scrub Typhus Detect™ Immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) test, of which 502 (35.90%) patients tested positive and were included in the study. Mean age of the patients was 30.37 ± 18.81 years (range, 1–79 years) with 26.29% in the pediatric age group. Female-to-male ratio was 1.26:1. Mean duration of fever was 6.8 ± 3.1 days. Mean IgM ELISA value for scrub typhus was 2.17 ± 1.70 without difference in AKI and non-AKI groups (2.17 ± 1.76 vs. 2.16 ± 1.62; P = 0.94). Urinary abnormalities were seen in 42.3% of patients. Mean serum creatinine was 1.37 ± 0.69 mg/dl with significant difference in two groups (1.85 ± 0.87 vs. 1.03 ± 0.17; P = 0.003). AKI was seen in 35.8% of patients with majority having Stage 1 AKI (68.3%) followed by Stage 2 (34.1%) and Stage 3 (1.2%). Hemodialysis was required for 3.94% of patients. In 54% of patients, AKI occurred in fifth and sixth day of fever. ICU admission was required for 18.73% of patients and 8.57% required ventilator support. Mortality rate was 1.79%, which was higher among patients with AKI (2.96% vs. 1.0%; P = 0.106). Multivariate analysis revealed that the presence of pneumonia, shock, and acute respiratory distress syndrome predicted the development of AKI.

ELISA Methods for the Detection of Ebolavirus Infection.

Ebola viruses are high-priority pathogens first discovered in rural Africa associated with sporadic outbreaks of severe hemorrhagic disease in humans and nonhuman primates. Little is known about the disease ecology or the prevalence of past exposure of human populations to any of the five species of the genus Ebolavirus. The use of immunologic means of detection for either virus antigens or the host's immune response to antigen associated with prior infections offers a powerful approach at understanding the epidemiology and epizootiology of these agents. Here we describe methods for preparing antigen detection sandwich enzyme-linked immunosorbent assays (ELISAs) as well as IgG and IgM ELISAs for the detection of ebolavirus antigens or antibodies in biological samples.

Safety and Efficacy of a Single Dose of Anti-D (WinRho®) in Severe Thrombocytopenia Secondary to Dengue Virus Infection.

Objective:To evaluate the efficacy of a single intravenous (IV) dose of anti-D in severe thrombocytopenia (<20,000) due to dengue virus (DEV) infection.Materials and Methods:An open label, investigator-initiated, randomized interventional study was conducted that included thirty dengue patients (all positive for IgM enzyme-linked immunosorbent assay) with severe thrombocytopenia (<20,000/mm3). Patients were randomized to receive anti-D (50 μg/kg single IV dose) plus supportive therapy or supportive therapy alone.Results:The rate of rise in platelet count was significantly high in the intervention group at 24, 36, and 48 h. At the end of 48 h, 60% patients in the intervention group achieved a platelet count of ≥50,000/mm3 as compared to 6.7% in the control group (P = 0.0019). The requirement of the platelet concentrate infusion in the control group was significantly higher, i.e. 342 ml (±193) as compared to the intervention group requiring only 187 ml (±79). The intervention group showed a significant improvement in bleeding manifestations in all the patients by 24 h in Grade 2 bleed (P = 0.032) and by 48 h in Grade 1 bleed (P = 0.014).Conclusions:Severe thrombocytopenia (≤20,000/mm3) secondary to DEV infection was rapidly and safely reversed by administration of a single dose of 50 μg/kg (250 IU/kg) anti-D IV.

A Comparative Study of Assay Performance of Commercial Hepatitis E Virus Enzyme-Linked Immunosorbent Assay Kits in Australian Blood Donor Samples.

Hepatitis E virus (HEV) is transfusion-transmissible and therefore poses a risk to blood transfusion safety. Seroprevalence studies are useful for estimating disease burden and determining risk factors. Considerable variability in the sensitivity of HEV antibody detection assays exists. This study aimed to compare the performances of commercially available HEV enzyme-linked immunosorbent assays (ELISA) in Australian blood donor samples. Plasma samples that tested positive (n = 194) or negative (n = 200) for HEV IgG (Wantai HEV IgG ELISA) were selected. Of the 194 HEV IgG positive samples, 4 were positive for HEV IgM (Wantai HEV IgM ELISA). All samples were tested with the MP Diagnostics: HEV IgG ELISA, total (IgG, IgM, and IgA) HEV antibody ELISA, and HEV IgM ELISA. Of the 194 Wantai HEV IgG positive samples, 92 (47%) tested positive with the MP Diagnostics HEV IgG ELISA (κ = 0.47) and 126 (65%) with MP Diagnostics total HEV antibody assay (κ = 0.65). There was poor agreement between Wantai and MP Diagnostics HEV IgM assays. This study demonstrated poor agreement between the assays tested. These observations are consistent with previous reports demonstrating significant variability between HEV ELISAs, highlighting that results of HEV serology should be interpreted with caution.

Comparison of MagPix Assays and Enzyme-Linked Immunosorbent Assay for Detection of Hemorrhagic Fever Viruses

Viral hemorrhagic fevers, because of their high mortality rates, the lack of medical countermeasures, and their potential use as instruments of bioterrorism, pose a significant threat to the developed and the developing areas of the world. The key to preventing the spread of these diseases is early and accurate detection. For decades, the gold-standard immunoassay for hemorrhagic fever detection has been the enzyme-linked immunosorbent assay (ELISA); however, newer technologies are emerging with increased sensitivities. One such technology is the Luminex MagPix platform using xMAP microspheres. Here, we compare the MagPix platform with a traditional ELISA for IgM and antigen detection of infections from Lassa and Ebola viruses (LASV and EBOV, respectively). For IgM detection in nonhuman primate samples, the MagPix platform was 5 and 25 times more sensitive in detecting LASV and EBOV, respectively, compared to that with ELISA. For antigen detection in buffer, the MagPix platform was 25 and 2.5 times more sensitive in detecting lower levels of LASV and EBOV, respectively. In both IgM and antigen detection assays, the MagPix platform demonstrated excellent reproducibility at the lower limit of detection (LLOD). These findings demonstrate that the MagPix platform is a viable diagnostic replacement for the ELISA for viral hemorrhagic fevers.

Dengue Virus Seroconversion in Travelers to Dengue-Endemic Areas.

We conducted a prospective study to measure dengue virus (DENV) antibody seroconversion in travelers to dengue-endemic areas. Travelers seen in the Boston Area Travel Medicine Network planning to visit dengue-endemic countries for ≥ 2 weeks were enrolled from 2009 to 2010. Pre- and post-travel blood samples and questionnaires were collected. Post-travel sera were tested for anti-DENV IgG by indirect IgG enzyme-linked immunosorbent assay (ELISA) and anti-DENV IgM by capture IgM ELISA. Participants with positive post-travel anti-DENV IgG or IgM were tested for pre-travel anti-DENV IgG and IgM; they were excluded from the seroconversion calculation if either pre-travel anti-DENV IgG or IgM were positive. Paired sera and questionnaires were collected for 62% (589/955) of enrolled travelers. Most participants were 19-64 years of age, female, and white. The most common purposes of travel were tourism and visiting friends and relatives; most trips were to Asia or Africa. Median length of travel was 21 days. DENV antibody seroconversion by either anti-DENV IgM or IgG ELISA was 2.9-6.8%; lower range percent excluded potential false-positive anti-DENV IgG due to receipt of yellow fever or Japanese encephalitis vaccines at enrollment; upper range percent excluded proven false-positive anti-DENV IgM. Eighteen percent of those with seroconversion reported dengue-like symptoms. Seroconversion was documented for travel to Africa as well as countries and regions known to be highly dengue endemic (India, Brazil, southeast Asia). Given widespread risk of dengue, travel medicine counseling should include information on risk of dengue in endemic areas and advice on preventing insect bites and seeking prompt medical attention for febrile illness.

Clinical and Serological Insights from the Asian Lineage Chikungunya Outbreak in Grenada, 2014: An Observational Study.

Chikungunya virus (CHIKV) spread rapidly throughout the Caribbean region in 2014, and the first serologically confirmed case was seen in Grenada in July. This study investigated the outbreak of CHIKV in Grenada to identify the distinguishing clinical manifestations and the symptoms that corresponded the closest with serological test results. Sera were tested by IgM enzyme-linked immunosorbent assay and polymerase chain reaction to distinguish between cases positive or negative for CHIKV. Of 493 cases, 426 (86%) tested positive for CHIKV. The diagnostic decision rule, "Define as CHIKV positive a patient presenting with joint pain and any combination of fever, body pain, or rash," produced the closest agreement (85%) with the serological test results (Cohen's kappa, k = 0.289, P value < 0.001). When laboratory facilities are not available for diagnostic confirmation, syndromic surveillance using these four symptoms could be useful to define cases during a CHIKV outbreak when CHIKV is the predominant circulating arbovirus.