Computer Diagnosis of Congenital Heart Disease

book chapterBiomedical Informatic

Molecular Analysis of Group A Streptococcus Type emm18 Isolates Temporally Associated with Acute Rheumatic Fever Outbreaks in Salt Lake City, Utah

Acute rheumatic fever (ARF) and subsequent rheumatic heart disease are rare but serious sequelae of group A Streptococcus (GAS) infections in most western countries. Salt Lake City (SLC), Utah, and the surrounding intermountain region experienced a resurgence of ARF in 1985 which has persisted. The largest numbers of cases were encountered in 1985-1986 and in 1997-1998. Organisms with a mucoid colony phenotype when grown on blood agar plates were temporally associated with the higher incidence of ARF. To develop an understanding of the molecular population genetic structure of GAS strains associated with ARF in the SLC region, 964 mucoid and nonmucoid pharyngeal isolates recovered in SLC from 1984 to 1999 were studied by sequencing the emm gene. Isolates with an emm18 allele were further characterized by sequencing the spa, covR, and covS genes. Peak periods of ARF were associated with GAS isolates possessing an emm18 allele encoding the protein found in serotype M18 isolates. Among the serotype M18 isolates, the difference in the number of C repeats produced three size variants. Variation was limited in spa, a gene that encodes a streptococcal protective antigen, and covR and covS, genes that encode a two-component regulatory system that, when inactivated, results in a mucoid phenotype and enhanced virulence in mouse infection models. Pulsed-field gel electrophoresis showed a single restriction profile for serotype M18 organisms isolated during both peak periods of ARF. In SLC, the incidence of ARF coresurged with the occurrence of GAS serotype M18 isolates that have very restricted genetic variation

The resurgence of rheumatic fever in a developed country area: the role of echocardiography.

OBJECTIVES: The annual incidence of ARF ranges from 5 to 51/100, 000 population worldwide in the 5- to 15-year age group. In the past, there was a decline in the incidence of ARF; however, focal outbreaks have been reported. This study evaluated the incidence of ARF in 2007-08 in a region of a developed country compared with the previous decade. METHODS: A retrospective review of all admission records for ARF in Trieste between January 2007 and December 2008 was undertaken. The diagnosis of ARF was established by the Jones criteria according to the 1992 revision. RESULTS: Between January 2007 and December 2008: 13 cases of ARF were recorded, 11 females and 2 males. The estimated incidence was 23 and 27/100, 000 population new cases each year, respectively, in the 5- to 15-year age group. Migratory polyarthritis occurred in 6/13, chorea in 7/13 and clinical carditis in 5/13 cases. Five out of 13 patients had only echocardiographic abnormalities, with no clinical cardiac manifestations. Another two patients did not fulfil diagnostic criteria for ARF, presenting with only three minor criteria, but they revealed silent carditis at echocardiography evaluation. During the follow-up, in one case the carditis receded and in the other it significantly improved. CONCLUSIONS: Our experience underlines that ARF has not yet disappeared in industrialized countries. We observed a high incidence of chorea, always associated with mild carditis. Echocardiographic assessment should be routinely performed in all patients with suspected ARF in order to identify those subclinical cases of valvulitis that would otherwise pass undiagnosed without receiving proper prophylaxis

Priming the immune system for heart disease: A perspective on group a streptococci

Although immune responses against group A streptococci and the heart have been correlated with antibodies and T cell responses against cardiac myosin, there is no unifying hypothesis about carditis caused globally by many different serotypes. Our study identified disease-specific epitopes of human cardiac myosin in the development of rheumatic carditis in humans. We found that immune responses to cardiac myosin were similar in rheumatic carditis among a small sample of worldwide populations, in which immunoglobulin G targeted human cardiac myosin epitopes in the S2 subfragment hinge region within S2 peptides containing amino acid residues 842-992 and 1164-1272. An analysis of rheumatic carditis in a Pacific Islander family confirmed the presence of potential rheumatogenic epitopes in the S2 region of human cardiac myosin. Our report suggests that cardiac myosin epitopes in rheumatic carditis target the S2 region of cardiac myosin and are similar among populations with rheumatic carditis worldwide, regardless of the infecting group A streptococcal M serotype

D8/17 and CD19 Expression on Lymphocytes of Patients with Acute Rheumatic Fever and Tourette's Disorder

D8/17, an alloantigen found on B lymphocytes, has been reported to be elevated in patients susceptible to rheumatic fever and may be associated with autoimmune types of neuropsychiatric disorders. The pediatric-autoimmune-neuropsychiatric-disorders-associated-with-streptococci model is a putative model of pathogenesis for a group of children whose symptoms of obsessive-compulsive disorder and Tourette's disorder (TD) are abrupt and may be triggered by an infection with group A streptococci. As a test of this model, we have examined D8/17 levels on the B cells of patients with TD and acute rheumatic fever (ARF) along with those on the B cells of normal controls by flow cytometry. We have utilized several different preparations of D8/17 antibody along with a variety of secondary antibodies but have been unable to show an association with an elevated percentage of D8/17-positive, CD19-positive B cells in either ARF or TD. We did find, however, that the percentages of CD19-positive B cells in ARF and TD patients were significantly elevated compared to those in normal controls. Group A streptococcal pharyngitis patients also had an elevated percentage of CD19 B cells, however. These studies failed to confirm the utility of determining the percentage of B cells expressing the D8/17 alloantigen in ARF patients or our sample of TD patients. In contrast, the percentage of CD19-positive B cells was significantly elevated in ARF and TD patients, as well as group A streptococcal pharyngitis patients, suggesting a role for inflammation and/or autoimmunity in the pathogenesis of these disorders