Canine GM2-Gangliosidosis Sandhoff Disease Associated with a 3-Base Pair Deletion in the HEXB Gene.

BACKGROUND: GM2-gangliosidosis is a fatal neurodegenerative lysosomal storage disease (LSD) caused by deficiency of either ß-hexosaminidase A (Hex-A) and ß-hexosaminidase B (Hex-B) together, or the GM2 activator protein. Clinical signs can be variable and are not pathognomonic for the specific, causal deficiency. OBJECTIVES: To characterize the phenotype and genotype of GM2-gangliosidosis disease in an affected dog. ANIMALS: One affected Shiba Inu and a clinically healthy dog. METHODS: Clinical and neurologic evaluation, brain magnetic resonance imaging (MRI), assays of lysosomal enzyme activities, and sequencing of all coding regions of HEXA, HEXB, and GM2A genes. RESULTS: A 14-month-old, female Shiba Inu presented with clinical signs resembling GM2-gangliosidosis in humans and GM1-gangliosidosis in the Shiba Inu. Magnetic resonance imaging (MRI) of the dog's brain indicated neurodegenerative disease, and evaluation of cerebrospinal fluid (CSF) identified storage granules in leukocytes. Lysosomal enzyme assays of plasma and leukocytes showed deficiencies of Hex-A and Hex-B activities in both tissues. Genetic analysis identified a homozygous, 3-base pair deletion in the HEXB gene (c.618-620delCCT). CONCLUSIONS AND CLINICAL IMPORTANCE: Clinical, biochemical, and molecular features are characterized in a Shiba Inu with GM2-gangliosidosis. The deletion of 3 adjacent base pairs in HEXB predicts the loss of a leucine residue at amino acid position 207 (p.Leu207del) supporting the hypothesis that GM2-gangliosidosis seen in this dog is the Sandhoff type. Because GM1-gangliosidosis also exists in this breed with almost identical clinical signs, genetic testing for both GM1- and GM2-gangliosidosis should be considered to make a definitive diagnosis.

Field performance of a rapid point-of-care diagnostic test for antenatal syphilis screening in the Amazon region, Brazil.

We evaluated an immunochromatographic point-of-care (POC) syphilis test in 712 pregnant women under field conditions in remote communities of the Amazon region (Brazil), and identified risk factors for syphilis. Women were screened by POC test using whole blood obtained by fingerprick, the fluorescent treponemal antibody absorption (FTA-Abs) test as the gold standard and the Venereal Diseases Research Laboratory (VDRL) test to determine test performance in active syphilis. Multivariate analysis was conducted to identify factors associated with syphilis infection. Among women, 2.2% had syphilis (positive FTA-Abs) and 0.8% active syphilis (FTA-Abs and VDRL positive). In all, 2.2% of samples were positive by the POC test. The sensitivity, specificity, positive and negative predictive values were 62.5% (95% confidence interval [CI]: 38.6-81.5), 99.1% (95% CI: 98.1-99.6), 62.5% (95% CI: 38.6-81.5) and 99.1% (95% CI: 98.1-99.6), respectively. The POC test identified 62.5% (10/16) of syphilis cases, 66.7% (4/6) of active syphilis cases and all high-titre syphilis cases (VDRL > 1:8). Older age was associated with syphilis infection. The rapid test performed moderately well as a screening tool for low-risk populations. This combined with on-site testing and same day treatment could expand antenatal syphilis screening programmes in distant communities characterized by difficult access to antenatal services and infrequent clinical follow-up visits.

Field evaluation of the performance and testing costs of a rapid point-of-care test for syphilis in a red-light district of Manaus, Brazil.

OBJECTIVES: To assess the performance, usefulness and cost of a rapid treponemal antibody assay (VisiTect Syphilis) to detect syphilis in high risk populations. METHODS: People who attended STI clinics in Manaus, Brazil, were screened for syphilis using the fluorescent treponemal antibody absorption (FTA-Abs) test and a non-treponemal test (Venereal Diseases Research Laboratory (VDRL)), and for HIV. Finger prick blood samples were tested with VisiTect Syphilis. The rapid test was evaluated against the reference FTA-Abs and for its usefulness in detecting active syphilis (FTA-Abs and VDRL positive). Operational performance was assessed through providers' and patients' interviews. An economic evaluation was conducted from the provider's perspective. RESULTS: 510 patients (60% men) were enrolled, of whom 13 (2.5%) were HIV-1 seropositive. Syphilis prevalence (FTA-Abs) was 18% and active syphilis prevalence was 7.5%. 11% (57/506) of samples were positive by VisiTect. The sensitivity, specificity, positive and negative predictive values of VisiTect Syphilis were 57% (95% CI 45.8 to 66.7), 99% (95% CI 97.0 to 99.6), 91% (95% CI 80.0 to 96.7) and 91% (95% CI 88.0 to 93.5), respectively. VisiTect Syphilis identified 79% (30/38) of active syphilis cases. The cost per case of syphilis was $16.8 for VDRL, $33.2 for low cost and $56.3 for high cost VisiTect Syphilis; the cost per case of active syphilis was $21.3, $57.5 and $97.6, respectively. Patients identified finger prick pain and preference for venous blood collection as minor barriers to test use. CONCLUSION: VisiTect Syphilis had low sensitivity in field use and was less cost effective than conventional VDRL. However, rapid and correct identification of a high proportion of active syphilis cases combined with operational characteristics suggest a role in high risk populations.

Diagnosis of gonococcal infection in high risk women using a rapid test.

OBJECTIVE: To assess the performance and acceptability for patients and health care workers of the NGThermo Biostar (GC OIA) to diagnose gonococcal infection compared with culture using modified Thayer Martin medium. METHODS: This study involved 326 high-risk women presenting with vaginal discharge or referral by sexual partner with urethral discharge at a sexually transmitted infections (STI) clinic in Manaus, Brazil. Endocervical swabs collected from the women were tested with both the NG Biostar and modified Thayer Martin culture as the reference standard test. Clinic staff were trained to perform the NG Biostar on site and the culture was performed in the laboratory of the clinic. RESULTS: The prevalence of gonococcal infection as measured by the reference standard was 15% (50/326) overall. Among asymptomatic participants, the prevalence of infection was 17.7% (25/141) and among symptomatic women it was 13.5% (25/185) (p = 0.3). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the NG Biostar test, with 95% confidence intervals (CI), were 60% (46.4% to 73.6%), 89.9% (86.2% to 93.6%), 55.6% (42.4% to 68.8%), and 92.6% (89.5% to 95.7%), respectively; 98.8% of study participants were willing to wait approximately 1 hour in the clinic for test results. CONCLUSION: Syndromic management protocols for treatment of STI in developing countries require refinement because, as currently described, they lead to over-treatment of cervical infection. A rapid test done during patients' initial presentation and leading to immediate treatment if positive would help improve the accuracy of diagnosis and could also be used to screen asymptomatic women. Even though the NG Biostar had a low sensitivity and PPV, which is less than ideal, it could still improve the rates of treatment over the gold standard test that requires return visits for patients to receive results and to benefit from treatment. Cost-effectiveness studies using rapid point-of-care tests for Neisseria gonorrhoeae infection compared to the syndromic approach should be carried out to assess their value in STI diagnosis and treatment in developing nations.

Prospective, multi-centre clinic-based evaluation of four rapid diagnostic tests for syphilis.

OBJECTIVES: To evaluate prospectively four rapid, point-of-care serological tests for syphilis in prenatal or high risk populations in four countries. METHODS: Tests were performed on consecutive clinic attenders, using whole blood in the clinic, and whole blood and serum in the laboratory. The sensitivity and specificity of each test was evaluated, using a standard treponemal test (Treponema pallidum haemagglutination assay (TPHA) or fluorescent treponemal antibody, absorbed (FTA-ABS) as gold standard. Non-treponemal tests (rapid plasma reagin (RPR) or venereal diseases research laboratory (VDRL) tests) were also performed on all subjects at three sites. RESULTS: The specificity of each rapid test was >95% at each site. Sensitivities varied from 64-100% and, in most cases, were lower when whole blood was used rather than serum. CONCLUSIONS: Rapid serological tests for syphilis are an acceptable alternative to conventional laboratory tests. Since they do not require equipment or electricity, they could increase coverage of syphilis screening, and enable treatment to be given at the first clinic visit.