Epidemic Leptospirosis Associated with Pulmonary Hemorrhage—Nicaragua, 1995

In October 1995, epidemic “hemorrhagic fever,” without jaundice or renal manifestations, was reported in rural Nicaragua following heavy flooding; 2259 residents were evaluated for nonmalarial febrile illnesses (cumulative incidence, 6.1%) and 15 (0.7%) died with pulmonary hemorrhage. A case-control study found that case-patients were more likely than controls to have ever walked in creeks (matched odds ratio [MOR], 15.0; 95% confidence interval [CI], 1.7–132.3), have household rodents (MOR, 10.4; 95% CI, 1.1–97.1), or own dogs with titers ≥ 400 to Leptospira species (MOR, 23.4; 95% CI, 3.6–`). Twenty-six of 51 case-patients had serologic or postmortem evidence of acute leptospirosis. Leptospira species were isolated from case-patients and potential animal reservoirs. This leptospirosis epidemic likely resulted from exposure to flood waters contaminated by urine from infected animals, particularly dogs. Leptospirosis should be included in the differential diagnosis for nonmalarial febrile illness, particularly during periods of flooding or when pulmonary hemorrhage occurs

Two-Component Direct Fluorescent-Antibody Assay for Rapid Identification of Bacillus anthracis

A two-component direct fluorescent-antibody (DFA) assay, using fluorescein-labeled monoclonal antibodies specific to the Bacillus anthracis cell wall (CW-DFA) and capsule (CAP-DFA) antigens, was evaluated and validated for rapid identification of B. anthracis. We analyzed 230 B. anthracis isolates; 228 and 229 were positive by CW-DFA and CAP-DFA assays, respectively. We also tested 56 non–B. anthracis strains; 10 B. cereus and 2 B. thuringiensis were positive by the CW-DFA assay, and 1 B. megaterium strain was positive by CAP-DFA. Analysis of the combined DFA results identified 227 of 230 B. anthracis isolates; all 56 strains of the other Bacillus spp. were negative. Both DFA assays tested positive on 14 of 26 clinical specimens from the 2001 anthrax outbreak investigation. The two-component DFA assay is a sensitive, specific, and rapid confirmatory test for B. anthracis in cultures and may be useful directly on clinical specimens

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Evaluation of the Indirect Hemagglutination Assay for Diagnosis of Acute Leptospirosis in Hawaii

Timely diagnosis of leptospirosis is important to ensure a favorable clinical outcome. The definitive serologic assay, the microscopic agglutination test (MAT), requires paired sera and is not useful for guiding early clinical management. The only screening test approved for use in the United States, the indirect hemagglutination assay (IHA), has not undergone extensive field evaluation. To assess the performance of the leptospirosis IHA in Hawaii, serum from patients evaluated for leptospirosis between 1992 and 1997 were tested with the IHA at the Hawaii State Laboratories Division and with the MAT at the Centers for Disease Control and Prevention. Leptospirosis was considered confirmed by a fourfold rise in MAT titer and/or a positive culture. A total of 92 (41%) of 226 specimens from 114 persons with confirmed leptospirosis were found positive by IHA. Only 18 (15%) of 119 specimens obtained within 14 days of onset were IHA positive, compared to 74 (69%) of 107 specimens collected more than 14 days after onset (P <0.001). Repeat testing ultimately resulted in 78 (68%) of the confirmed cases having at least one specimen found positive by IHA. Thirteen different presumptive infecting serogroups were identified among 251 specimens with an MAT titer of ≥200 and obtained from persons with confirmed or probable leptospirosis. Fifty (68%) of 73 specimens with Icterohaemorrhagiae as the presumptive infecting serogroup were found positive by IHA, compared to 44 (47%) of 93 specimens with Australis as the presumptive infecting serogroup (P, 0.01). The IHA test was positive for 3 (1%) of 236 specimens from 154 persons without leptospirosis. The sensitivity of the leptospirosis IHA in Hawaii was substantially below figures reported previously, particularly early in the course of illness, limiting its usefulness for diagnosing acute infection. Since the presumptive infecting serogroup affected IHA results and the prevalence of serovars varies with geography, the performance of the IHA should be assessed locally. More sensitive leptospirosis screening tests are needed in Hawaii

Production and Evaluation of Reagents for Detection of Histoplasma capsulatum Antigenuria by Enzyme Immunoassay▿

The detection of urinary Histoplasma capsulatum polysaccharide antigen (HPA) by enzyme immunoassay (EIA) has proven useful for the presumptive diagnosis of histoplasmosis in AIDS patients. Assay limitations include (i) detection of a largely uncharacterized antigen and (ii) difficulty in reproducibly generating antibodies for use in the EIA. To improve antibody production for use in this test and to better understand the antigen being detected, we compared rabbit antibodies elicited using various immunization schedules, routes, and H. capsulatum-derived antigens. Antibodies were evaluated by EIA for their ability to detect purified H. capsulatum C antigen (C-Ag) and antigenuria. Reported as enzyme immunoassay (EI) units (the A450 with antigen divided by the A450 without antigen), results demonstrated that intravenous immunization of rabbits with whole, killed yeast-phase cells (yeast-i.v. regimen) produced antibodies giving the highest EI values in the C-Ag EIA (mean EI units ± standard deviation, 14.9 ± 0.6 versus 6.4 ± 0.4 for rabbits immunized with C-Ag versus 2.4 ± 0.3 for all other regimens combined). Yeast-i.v. antibodies were highly sensitive for the detection of antigenuria in patients with histoplasmosis, as shown by the following results: 12/12 patients compared to 10/12, 6/12, 3/12, and 3/12, respectively, for antibodies from rabbits immunized with (i) C-Ag; (ii) whole, killed yeast-phase cells administered subcutaneously and intramuscularly; (iii) yeast-phase culture filtrates; and (iv) HPA-positive urine. Rabbits immunized using the yeast-i.v. regimen also gave higher peak antibody titers than rabbits immunized by any other regimen (P < 0.03), and their antibodies were most comparable in reactivity to antibodies produced for use in the standard HPA-EIA test (P < 0.001). Therefore, rabbits immunized using the yeast-i.v. regimen produced the most sensitive antibodies with the highest titers for detection of C-Ag and antigenuria in histoplasmosis patients

Evaluation of Four Commercially Available Rapid Serologic Tests for Diagnosis of Leptospirosis

Four rapid tests for the serologic diagnosis of leptospirosis were evaluated, and the performance of each was compared with that of the current standard, the microscopic agglutination test (MAT). The four rapid tests were a microplate immunoglobulin M (IgM)-enzyme-linked immunosorbent assay (ELISA), an indirect hemagglutination assay (IHA), an IgM dipstick assay (LDS), and an IgM dot-ELISA dipstick test (DST). A panel of 276 sera from 133 cases of leptospirosis from four different geographic locations was tested as well as 642 sera from normal individuals or individuals with other infectious or autoimmune diseases. Acute-phase sera from cases (n = 148) were collected ≤14 days (median = 6.0) after the onset of symptoms, and convalescent-phase sera (n = 128) were collected ≥15 days after onset (median = 29.1). By a traditional method (two-by-two contingency table), the sensitivities for detection of leptospirosis cases were 93.2% by LDS, 92.5% by DST, 86.5% by ELISA, and 79.0% by IHA. Specificity was 98.8% by DST, 97% by ELISA and MAT, 95.8% by IHA, and 89.6% by LDS. With a latent class analysis (LCA) model that included all the rapid tests and the clinical case definition, sensitivity was 95.5% by DST, 94.5% by LDS, 89.9% by ELISA, and 81.1% by IHA. The sensitivity and specificity estimated by the traditional methods were quite close to the LCA estimates. However, LCA allowed estimation of the sensitivity of the MAT (98.2%), which traditional methods do not allow. For acute-phase sera, sensitivity was 52.7% by LDS, 50.0% by DST, 48.7% by MAT and ELISA, and 38.5% by IHA. The sensitivity for convalescent-phase sera was 93.8% by MAT, 84.4% by DST, 83.6% by LDS, 75.0% by ELISA, and 67.2% by IHA. A good overall correlation with the MAT was obtained for each of the assays, with the highest concordance being with the DST (kappa value, 0.85; 95% confidence interval [CI], 0.8 to 0.90). The best correlation was between ELISA and DST (kappa value, 0.86; 95% CI, 0.81 to 0.91). False-positive LDS results were frequent (≥20%) in sera from individuals with Epstein-Barr virus, human immunodeficiency virus, and periodontal disease and from healthy volunteers. The ease of use and significantly high sensitivity and specificity of DST and ELISA make these good choices for diagnostic testing

International Multicenter Evaluation of the Clinical Utility of a Dipstick Assay for Detection of Leptospira-Specific Immunoglobulin M Antibodies in Human Serum Specimens

We performed a multicenter evaluation of a robust and easily performed dipstick assay for the serodiagnosis of human leptospirosis. The assay is aimed at the detection of Leptospira-specific immunoglobulin M (IgM) antibodies. The study involved 2,665 serum samples collected from 2,057 patients with suspected leptospirosis in 12 countries on five continents with different levels of endemicity and different surveillance systems. The patients were grouped as laboratory-confirmed leptospirosis case patients and noncase patients based on the results of culturing and the microscopic agglutination test. Paired samples from 27.7% of the subjects were tested. Of the 485 case patients, 87.4% had a positive dipstick result for one or more samples. Of the 1,513 noncase patients, only 7.2% had a positive result. Whereas most (88.4%) of the positive samples from the case patients showed moderate to strong (2+ to 4+) staining in the dipstick assay, most (68.1%) of the positive samples from the noncase patients showed weak (1+) staining. The sensitivity of the dipstick assay increased from 60.1% for acute-phase serum samples to 87.4% for convalescent-phase samples. The specificities for these two groups of samples were 94.1 and 92.7%, respectively. The dipstick assay detected a broad variety of serogroups. The results of the dipstick assay were concordant (observed agreement, 93.2%; kappa value, 0.76) with the results of an enzyme-linked immunosorbent assay for the detection of specific IgM antibodies, a test which is often used in the laboratory diagnosis of current or recent leptospirosis. This study demonstrated that this easily performed dipstick assay is a valuable and useful test for the quick screening for leptospirosis; has a wide applicability in different countries with different degrees of endemicity; can be used at all levels of the health care system, including the field; and will be useful for detecting and monitoring outbreaks of leptospirosis