Secular trends in menopause age

Serum and colostrum from 73 sows were collected. The serum samples were tested by Immuno. Peroxidase Monolayer Assay (IPMA) and the corresponding colostrum samples with the indirect Immuno fluorescent Antibody (IFA) technique. All serum positive sows were colostrum positive and all colostrum negative were serum negative. Eight sows only reacted positively in the colostral testing. Compared to the serum standard test the specificity was 82.6% and the sensitivity 100%. The observed agreement between both tests was 89.2%. In addition all serum samples were also tested with the IF test (IFT). Of the eight sows which were negative in the IPMA serum test and positive in the IFA colostrum test, three were found positive when the serum was tested with IFA. Consequently, the observed agreement was higher at 93.2%. After the suitability of colostrum for porcine reproductive and respiratory syndrome (PRRS) diagnosis was demonstrated, 1915 colostrum samples collected from 135 different farms were tested in a comparative study with the IPMA and IFA techniques. Of the 1915 colostrum samples 139 were positive with both IPMA and IFA. With IPMA only, 43 samples were positive compared with 192 samples found positive with the IFA technique. A total of 1541 samples were negative in both tests. The observed agreement between both tests was 87.5%. The quotient of the observed agreement minus chance agreement and the maximum possible agreement beyond chance level (Kappa Quotient) was 0.49. In 90% of the farms that tested IFA positive there was a seroconversion of more than 50% of all colostrum tested. By comparison only 29% of the IPMA positive farms were positive with more than 50%. Based on the epidemiological findings on PRRS it was concluded that the IFA technique indicates a higher sensitivity for the detection of PRRS virus antibodies in sow colostrum. Finally the possible advantages and disadvantages of sow colostrum testing and serum testing are discussed.     

ACP Broadsheet No 152: March 1998. Clinical implications of plasma homocysteine measurement in cardiovascular disease

Enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) are the most widely used serological tests for Maedi-Visna diagnostics. The purpose of the present study was to develop an indirect whole virus ELISA and an immunodiffusion test and compare their sensitivity. A total of 747 ovine serum specimens were analysed for antibodies against this ovine lentivirus. The number of positive results in the ELISA was 430 (57.56%). In the AGID test, a positive result was found in 380 samples (50.87%). In the group of discordant results 78 (10.4%) samples tested positive by the ELISA and negative by the AGID test and 28 sera (3.7%) were found to be positive by the AGID test and negative by the ELISA. The data in this report show the ELISA to be more sensitive than the AGID test, but accurate serological diagnostics should be based on a combination of the two tests.     

Macrophages infected with bovine leukaemia virus (BLV) induce humoral response in rabbits

BLV is a lymphotropic retrovirus which infects mainly B-cells. However, the possible infection of cells of the monocyte/macrophage lineage (M/M) might explain some aspects of the disease such as latency or disease progression. We infected sheep M/M with BLV either by culturing M/M with supernatant containing virus, or coculturing M/M with persistently infected cell lines. These BLV-infected M/M were inoculated into rabbits and the serological response was followed for two years. ELISA results using adsorbed sera showed a persistent production of specific antibodies from as early as the first week post inoculation. Two tests were used to detect the response against envelope glycoprotein gp51: Agar gel immunodiffusion (AGID) and a virus neutralization test read as syncytia inhibition (SI). Sera were positive by AGID after the second or third inoculation. Neutralizing titres (SI) were higher than those seen in control rabbits inoculated with persistently infected cell lines, suggesting that the virus may be expressed better in M/M. Gag-related proteins were analyzed by Western Blot (WB). Sera from rabbits inoculated with BLV-infected M/M recognized as many viral proteins as sera from BLV immunized control rabbits or infected cows, and this profile did not change with repeated inoculations. All these results suggest that BLV may infect M/M, where viral proteins are actively expressed to the point that they induce a humoral immune response in animals, and that animals get persistently infected.     

Clonal relationships among high-level penicillin-resistant Streptococcus pneumoniae in the United States

Emu antibody responses to avian influenza virus (AIV) infection were evaluated by the competitive enzyme-linked immunosorbent assay (C-ELISA), agar gel immunodiffusion (AGID) and hemagglutination inhibition (HI) tests. All birds infected with AIV H5N1, H5N3, or H7N7 developed antinucleoprotein (NP) antibodies as early as 7 days postinfection as detected by the C-ELISA. The responses lasted 49 days for the emus receiving H5N3 and at least 56 days for emus receiving the other two viruses. By evaluating 50 emu field serum samples, the C-ELISA was found more sensitive than the AGID test for the detection of anti-NP antibodies. This study indicates that emus experimentally infected with AIV developed antibody responses that can be detected by C-ELISA, AGID, and HI tests. The results from this and our previous studies demonstrate the use of the C-ELISA as a substitute for the AGID test in a routine serodiagnostic screening for detection of antibodies to AIV infection in multiple avian species.     

Detection of virus infection-associated antigen and 3D antibodies in cattle vaccinated against foot and mouth disease

The analysis of sera obtained from animals vaccinated or revaccinated with inactivated vaccines against foot and mouth disease (FMD) virus showed that these vaccines induced antibodies against the virus infection-associated (VIA) antigen, detectable by agar gel immunodiffusion (AGID). The present study evaluates the antibody response to protein 3D and the VIA antigen (VIAA) of FMD virus induced by different vaccines in a group of 51 calves. This response was detected using AGID and a liquid-phase blocking sandwich enzyme-linked immunosorbent assay (ELISA) for anti-3D antibodies (ELISA-3D). No anti-VIAA or anti-3D antibodies were detected after the initial vaccination. Following revaccination, animals giving positive results were detected by both methods. This immune response disappeared 60-120 days post-revaccination (dprv) according to the AGID method, and 90-180 dprv when ELISA-3D was used. Samples of oesophageal-pharyngeal fluid obtained from animals that remained positive for anti-VIAA antibodies at 90-120 dprv gave negative results for viral isolation, indicating that the transitional antibody response induced by the vaccine was due to the presence of non-structural antigens in the vaccine and not to viral infection. These results indicate that the ELISA-3D method could be used as a complementary method for sero-epidemiological studies as an indirect indicator of viral activity, as long as the age and vaccination status of the animals being sampled are taken into consideration.     

Pathological and epidemiological aspects of the coexistence of maedi-visna and sheep pulmonary adenomatosis

Between 1982 and 1991, 159 sheep suffering from chronic respiratory disease were subjected to clinical, pathological, histopathological and serological examination. Maedi was diagnosed in 82 sheep and sheep pulmonary adenomatosis (SPA) in another 59. Forty-one of the latter (69.5 per cent) were seropositive for maedi-visna (MV) virus infection, but only six (10.2 per cent) showed concurrent lung lesions of maedi. Even disregarding the MV seronegative sheep and those younger than two years old, the rate of concurrent maedi lesions did not exceed 18 per cent. During a similar period, 5060 sheep from 161 flocks (86 of which also provided the 159 affected animals) were tested for antibodies to MV virus. The average seroprevalence of MV virus infection among flocks in which SPA was detected was 66.4 per cent, whereas in those in which SPA could not be demonstrated, and in those in which necropsies were not performed, the levels of MV virus infection were 55.1 per cent and 43.6 per cent, respectively. The effect of SPA on the seroprevalence of MV virus infection was independent of other factors, such as breed of sheep or the size of the flocks. These results provide evidence that SPA plays a role in the spread of MV virus infection, although a synergistic effect of the simultaneous infection on the expression of concurrent lesions does not seem to occur.     

Prevalence of Toxoplasma gondii antibodies in wild and domestic animals in northern California

Wild and domestic animals from 3 geographic-climatologic areas in northern California were tested for antibodies against Toxoplasma gondii. A total of 2,796 serum samples representing 37 species of wild mammals, 35 species of wild birds, and 5 species of domestic animals were tested by the indirect hemagglutination test. Of 1,174 wild mammal serums tested, 10.8% were positive, which compared with 14.7% of the 1,221 domestic mammal serums. Of 229 wild carnivores tested, 45% were seropositive, including 69% of 86 bobcats, 28% of 58 coyotes, 48% of 25 raccoons, 27% of 26 gray foxes, 22% of 32 striped skunks, a civet cat, and a mink. Serologic evidence of infection was found in 38% of 47 rural domestic cats, but none of the 7 dogs tested was seropositive. Of 160 murid rodents (rats and house mice) in rural habitats, 4% were seropositive, which compared with 2% of 399 cricetine rodents (mostly deer mice) collected from wilderness habitats. Seven percent of 56 wild Artiodactyla (deer and feral pigs) were seropositive, which compared with 15% of 1,048 domestic sheep tested. Of 401 birds tested, 3.5% had antibodies against T gondii. The highest prevalence of antibodies among birds was in crows (14%). Toxoplasma was isolated from 1 raven, by mouse inoculation. In general, the highest prevalence of seropositive carnivores, rodents, and sheep was in the coastal region below 100 ft elevation, where the weather is cool and damp for much of the year. In the central valley the highest prevalence among sheep was in areas under irrigation. The prevalence of antibodies was lowest in the mountain areas, where climatologic extremes prevail at various seasons of the year.     

Prevention of carbon tetrachloride-induced hepatotoxicity in the rat by H. rosasinensis anthocyanin extract administered in ethanol

A serologic survey was carried out in order to detect antibodies against Babesia ovis in a large population of Spanish ibex (Capra pyrenaica) from a hunting reserve in Catalonia, northeastern Spain. For this purpose, an indirect fluorescent antibody test (IFAT) was developed using a B. ovis isolate of ovine origin as antigen. Of the total 475 sera tested, 155 (32.6%) showed titres between 1:160 and 1:1280 and were considered positive. These results reveal that exposure of Spanish ibex to B. ovis is common in the studied area. No significant differences could be detected when comparing season or year of capture and age or sex of the animals in positive and negative samples. A high proportion of low titres was found in comparison to those reported by other researchers in sheep in Spain; this could be a consequence of the existence of some minor antigenic differences between B. ovis of domestic sheep and that found in Spanish ibex.     

Fluorescent antinuclear antibody and anti-double-stranded DNA antibody testing: a four years experience

Fluorescent antinuclear antibody test (FANA) and anti-double stranded deoxytribonucleic acid (dsDNA) antibody testing is an integral part of the evaluation of the patients who are suspected of having connective tissue disease. We tested 2,140 serum samples for FANA and 1,460 serum samples for anti-dsDNA antibodies. Of 2,140 serum samples tested for FANA, 492 (23%) yielded a positive result (titre of 1:80 or greater) and of 1,460 serum samples tested for anti-dsDNA, 69 (4.7%) yielded positive results. Highest number (n = 27) of serum samples positive for anti-dsDNA antibodies were found in serum samples that were positive for FANA test at a titre of 1:1280 or greater. In conclusion, FANA test can be used as an initial screening test for connective tissue/autoimmune disorders.     

Involvement of dogs in plague epidemiology in Tanzania. Serological observations in domestic animals in Lushoto District

Venous blood was collected aseptically from clinically healthy domestic dogs, goats, sheep, cats and fowl in various plague-infected villages of Lushoto District, Tanzania, at the time when the disease was actively prevalent in the area. Flea ectoparasites were collected from the animals, processed, identified and counted. Serum samples were tested for specific plague antibodies, using the passive haemagglutination technique and checked by passive haemagglutination inhibition tests. Altogether 389 animals, of which 201 were domestic dogs, were involved. 11 (5.5%) dogs had significantly elevated specific plague antibodies at titres ranging from 20 to 1280. All the dogs were also heavily infested with fleas at a mean index of 7.7 fleas per animal. Of 1,871 fleas collected from the dogs, 93.8% were Ctenocephalides felis and 6.2% were C. canis. All the other animals examined were negative for plague. It was concluded that domestic dogs could play an important role as plague carriers in the area and that the animals could serve as sentinel animals for the detection of plague in villages where human plague outbreaks have not previously occurred.     

Overexpression of c-myc induces apoptosis at the prophase of meiosis of rat primary spermatocytes

Serum samples from 36 cervical carcinoma patients, 33 patients with high-grade squamous intraepithelial lesions, and 31 cytologically normal women were tested by enzyme-linked immunosorbent assay (ELISA) using human papilloma virus type 6 (HPV 6) and HPV 16 virus-like particles as antigens. Forty serum specimens from 1-year-old children were used to assign cutoff points. When serum samples from the subjects infected with HPV 16 were tested in an HPV 16 ELISA detecting immunoglobulin A (IgA), IgG, and IgM binding, 61% showed IgA, 44% showed IgG, and 39% showed IgM reactivity. Of HPV 6- or 11- or HPV 18-infected subjects. fewer than 17% showed IgA or IgG responses and 33% showed IgM reactivity. In contrast, 13% showed IgA, 10% showed IgG, and 16% showed IgM reactivity in the HPV DNA-negative controls. The results suggest that the IgA and IgG responses are HPV 16 specific and the IgM response is cross-reactive to different HPV types. On the other hand, the serological responses to HPV 6 did not differ in the patient and control groups. The percentages of patients positive for both IgA and IgG antibodies were significantly higher in the groups with high-grade squamous intraepithelial lesions (12% [4 of 33]; P = 0.04) and cancer (17% [6 of 36]; P = 0.02) than in the healty women (0% [0 of 31]), and the percentages for either IgA or IgG were higher for the cancer group (47% [17 of 36]; P = 0.01) than in the normal group (19% [6 of 31]). Most sera positive for IgA and IgG in the patient groups showed higher titers than those in the normal group. All these results suggest that high IgA and IgG responses are good indicators for estimating HPV 16 infection.     

Helicobacter pylori CagA antigen antibodies

BACKGROUND: CagA antigen of Helicobacter pylori is highly immunogenic in humans. There is an increasing evidence that infection with CagA-positive strains is related to the development of peptic ulcer disease, atrophic gastritis, or gastric cancer. The aim of our study was to assess seropositivity to CagA in a group of 95 clinically symptomatic adults who underwent gastroduodenoscopy and to correlate results to their disease characteristics. METHODS AND RESULTS: Serum immunoglobulin G antibodies to CagA detected by ELISA kit (Helicobacter p120, Viva Diagnostika, Germany) were compared to standard IgG specific antibodies against a pool of H. pylori antigens Synelisa Pin plate, ELIAS, Germany). Immunoglobulin G antibodies to CagA were present in 5/31 (16%) serum samples from H. pylori negative persons and 10/28 (36%) serum samples from H. pylori positive patients without peptic ulcer disease compared with 8/11 (73%) H. pylori positive patients with peptic ulcer disease in the past, 11/13 (85%) H. pylori positive patients with duodenal ulcers or duodenitis and 4/5 (80%) H. pylori positive (1/7, 14% H. pylori negative) serum samples from patients with gastric resection for peptic ulcers in the past. Serum levels of antibodies to CagA in the groups of patients with peptic ulcer disease in the past, with present duodenal ulcers of duodenitis and in H. pylori infected patients with gastric resection were significantly higher then those of H. pylori infected patients without peptic ulcer disease (P < 0.05). On the other hand, there was no significant difference in the presence of the specific antibodies against at pool of H. pylori antigens between these four groups. CONCLUSIONS: These data suggest that serologic response to the CagA antigen is more prevalent in H. pylori positive persons with present or past peptic ulceration than among infected persons without peptic ulcer disease. The presence of antibodies to CagA in H. pylori positive persons may be useful for the identification of patients with higher risk or more severe disease.     

Immunological detection of sheep experimentally infected with strains of Mycobacterium avium subspecies containing insertion sequence IS901/IS902 and a 40 kDa protein

A monoclonal antibody raised against a 40 kDa protein present in certain M. avium strains (IS901/IS902 positive) was used for developing a blocking ELISA. Sera from experimentally infected sheep were evaluated by indirect ELISA, AGID and blocking ELISA. The blocking assay proved to be highly specific for differentiation of sheep infected with different subspecies of M. avium.     

Monoclonal antibody-based blocking enzyme-linked immunosorbent assay for specific detection and titration of peste-des-petits-ruminants virus antibody in caprine and ovine sera

A blocking enzyme-linked immunosorbent assay (B-ELISA), using two neutralizing monoclonal antibodies (MAbs), was established and compared with the virus neutralization test (VNT) for detecting specific peste-des-petits-ruminants virus (PPRV) antibody in caprine and ovine sera. This technique was developed because VNT, the only available specific serological test for PPRV and the cross-reactive rinderpest virus (RPV), is time-consuming and unaffordable for most laboratories in regions where both peste des petits ruminants and rinderpest occur. The test depends on the blocking of the binding of the MAb to a specific epitope in the presence of positive serum. Test conditions were optimized by using peste-des-petits-ruminants and rinderpest sera that were known to be VNT positive and negative. A blocking format, in which serum is preincubated with a solid-phase PPRV antigen and then incubated with the MAb, yielded levels of sensitivity and specificity superior to those of a competitive format, in which the two reagents are added simultaneously. A threshold value of 45% inhibition, representing the mean for a negative population (n = 277) plus 2.7 standard deviations, was adopted for routine screening. A total of 605 serum samples were screened by B-ELISA and the VNT. The sensitivity and specificity of B-ELISA relative to the VNT were 90.4 and 98.9%, respectively. Of 264 field serum samples tested, 11 (4.2%) could not be assayed by the VNT because of contamination or cytotoxicity; the overall agreement quotient between results of the two tests (n = 253) was 0.91. A high correlation (r>/=0.98) was observed between B-ELISA and the VNT for endpoint titration of sera (n=57). Because B-ELISA proved to be nearlyas sensitive and specific as the VNT while being simpler and more rapid, it would be an adequate substitute for the VNT for assessing herd immune status and for epidemiologic surveillance.     

Cell-mediated and humoral immunity in bulls infected with IBR/IPV virus (BHV 1)

Time-related changes in specific cell-mediated immunity (CMI) and in humoral immunity were monitored in 20 bulls, aging 12 to 16 months, in four groups, each consisting of 5 animals. Group I was experimentally and group III-naturally infected with BHV 1 virus, groups II and IV serving as control animals. Tests for CMI included delayed type hypersensitivity (DTH), leukocyte migration inhibitory factor (LMIF) and granulocyte migration inhibitor factor (GMIF-LIF-buffy coat leukocyte migration inhibitory factor) in the presence of BHV I antigen while humoral immunity was tested by serum induced neutralization of the virus (SN) and by estimation of serum IgG, IgG1, IgG2, IgM and IgA levels. Immunologic, virologic and clinical studies were performed two days before infection and 17 timed within 91 days after the infection in bulls of group I and II and 7 times within 42 days after developing the disease in bulls of groups III and IV. The results showed that positive CMI reactions appeared 3 to 4 weeks earlier than positive antibody titers in SN test. The antibodies belonged most probably to IgG1 and IgG2 subclasses.     

Large-scale use of liquid-phase blocking sandwich ELISA for the evaluation of protective immunity against aphthovirus in cattle vaccinated with oil-adjuvanted vaccines in Argentina

Specific serum activity levels against four reference strains of foot-and-mouth disease virus (FMDV) were evaluated from 1634 animals vaccinated with commercial quadrivalent oil vaccines and from 746 unvaccinated, naive animals, using the liquid-phase blocking sandwich ELISA (lpELISA) test. Cows from the FMDV-free area of Argentina were tested for the absence of specific FMDV antibodies (sp FMDV Abs) and those showing lpELISA titres < 1.0 were grouped in lots of 16 animals. They were vaccinated and challenged at 90 days postvaccination (DPV) with one of four virus strains used for vaccine production and control (prototype strains). Serum samples from vaccinated and control cattle were collected 60 and 90 DPV and the level of sp FMDV Abs was determined by lpELISA. Animals were examined for clinical signs of disease. Results show that serum lpELISA titre levels directly correlate with the percentage of protected animals. It was seen that 100, 98, 93 and 87% of the vaccinated cattle with antibody titre levels > or = 2.1 were protected against challenge with serotypes C85, A87,01 Cas and A79, respectively. Evidence is also presented of seroconversion in a sample of 3-5-month-old calves vaccinated in the field, showing lpELISA titres compatible with protection against the four vaccine viruses as long as 150 DPV. Results reported in this paper strongly support the use of the lpELISA test for a rapid and reliable evaluation of the efficacy of FMDV commercial vaccines as well as for the assessment of the immunological status of cattle in FMDV-free and enzootic regions of South America.     

The TC21 oncoprotein interacts with the Ral guanosine nucleotide dissociation factor

Serum specimens were collected from 6 species of animals living in 9 states of Malaysia including Sabah, North Borneo in 1993. Antibodies against Japanese encephalitis (JE) virus in these sera were detected by means of hemagglutination-inhibition (HI) and neutralization (NT) tests. By HI test, 702 of 2,152 (32.6%) sera showed positive results. Higher positive rates were obtained by the NT test, in which 1,787 of 1,927 (92.7%) sera had antibodies against JE virus. All serum specimens with positive HI were confirmed as positive by the NT. Swine sera showed especially higher rates of antibody positive and higher antibody titers compared with other animals. These results suggest that JE infections are widely distributed among many animals of Malaysia, and pig is the most susceptible amplifier host for JE virus.     

Evaluation of bluetongue virus diagnostic tests in free-ranging bighorn sheep

Five bluetongue virus (BTV) diagnostic tests were evaluated for use in free-ranging bighorn sheep. We sampled one bighorn sheep population four times between 1989 and 1995. The tests evaluated included virus isolation (VI), polymerase-chain reaction (PCR), serum neutralization (SN), agar-gel immunodiffusion (AGID), and competitive enzyme-linked immunosorbent assay (c-ELISA). The c-ELISA, AGID and SN tests had high levels of agreement in determining serogroup exposure in bighorn sheep. We used maximum-likelihood algorithms to estimate the parameters of each diagnostic test used. Although the c-ELISA and AGID had high sensitivity and specificity, the SN had perfect specificity but lower apparent sensitivity. Due to the potential of cross-reactions among multiple serotypes, results of the SN must be interpreted with caution when assessing serotype exposure in an area where multiple serotypes are endemic. The PCR assay delineated convalescent antibody titers from more-recent infections, and consequently, was pivotal in distinguishing a different exposure pattern between the bighorn sheep and cattle in an adjacent herd. Based on an increasing seroprevalence (50% to 100%), BTV circulated through this bighorn sheep population between 1989 and 1993. This increase in seroprevalence coincided with a bighorn die-off due to BTV infection in June, 1991. An adjacent cattle herd was sampled in 1995 for comparison. The bighorn sheep and adjacent cattle had different patterns of exposure to BTV between 1994 and 1995. There was no evidence that BTV circulated through the bighorn sheep population from 1994 to 1995. In 1995, seroprevalence to BTV decreased to 72%, none of yearling bighorn was seropositive, and all of the 39 bighorn sheep were PCR-negative. In contrast, all adult cattle were seropositive to BTV by c-ELISA and SN, and 4 of the calves were seropositive; 11 of the 24 cattle were PCR-positive, including all five calves. Overall, the pattern of temporal herd immunity in the bighorn sheep appeared to follow a classic epidemic curve, with the appearance and subsequent disappearance of herd immunity coinciding with the 1991 die-off in this population. As low levels of herd immunity and high proportions of susceptible animals are key factors in the development of epidemics, this population of bighorn sheep may be at increased risk for a BTV epidemic in the future.     

Evaluation of a rapid immunochromatographic test for diagnosis of dengue virus infection

A rapid (<7-min) immunochromatographic test for immunoglobulin M (IgM) and IgG antibodies to dengue viruses was evaluated by using hospital admission and discharge sera from 124 patients. The reference laboratory diagnosis was based on the results of virus isolation, hemagglutination-inhibition assay (HAI), and enzyme immunoassay (EIA). By the standard assays, patients experienced primary dengue virus infection (n = 30), secondary dengue virus infection (n = 48), Japanese encephalitis (JE) virus infection (n = 20), or no flavivirus infection (n = 26). The rapid test demonstrated 100% sensitivity in the diagnosis of dengue virus infection and was able to distinguish between primary and secondary dengue virus infections through the separate determinations of IgM and IgG. For all patients with primary dengue virus infection a positive test for IgM to dengue virus and a negative test for IgG to dengue virus were obtained, whereas for 46 of 48 patients (96%) with secondary dengue virus infection, a positive test for IgG to dengue virus with or without a positive test for IgM to dengue virus was obtained. The remaining two patients with secondary dengue virus infection had positive IgM test results and negative IgG test results. Furthermore, the rapid test was positive for patients confirmed to be infected with different dengue virus serotypes (12 infected with dengue virus serotype 1, 4 infected with dengue virus serotype 2, 3 infected with dengue virus serotype 3, and 2 infected with dengue virus serotype 4). The specificity of the test for nonflavivirus infections was 88% (3 of 26 positive), while for JE virus infections the specificity of the test was only 50% (10 of 20). However, most patients with secondary dengue virus infection were positive for both IgM and IgG antibodies to dengue virus, while no patients with JE virus infection had this profile, so cross-reactivity was only a concern for a small proportion of patients with secondary dengue infections. The rapid test demonstrated a good correlation with the reference EIA and HAI and should be useful for the rapid diagnosis of dengue virus infections.