Enfermedades exantemáticas virales: aspectos clinicoepidemiológicos y de laboratorio / Exanthematous viral diseases: clinical and laboratory aspects

Los cuadros exantemáticos tienen frecuentemente origen infeccioso; los virus son una causa importante de exantema. Los exantemas más relevantes son, entre los maculopapulosos, el sarampión, la rubéola, el eritema infeccioso y el exantema súbito y, entre los vesiculoampollosos, la varicela, el zóster y la enfermedad boca-mano-pie. Algunas de las anteriores, y otras infecciones virales, causan exantemas purpúricos que pueden ser de mayor gravedad. El diagnóstico de laboratorio se realiza de forma directa, mediante el aislamiento, la detección de antígenos o la detección del ácido nucleico viral, siendo esta última la aproximación más adecuada; o, serológicamente, por detección de IgM específica, que proporciona diagnóstico temprano, o de seroconversión. En general, ambas herramientas metodológicas se complementan para mejorar el rendimiento diagnóstico. La caracterización molecular es una importante actividad de laboratorio, especialmente para los virus del sarampión y de la rubéola, en el contexto del plan de eliminación de estas enfermedades (AU)

Exanthematous diseases frequently have an infectious origin; viruses are a major cause of rashes. The most notable maculopapular rashes are measles, rubella, infectious erythema and exanthem subitum, while the vesicular rashes include varicella (and zoster) and hand-foot-and-mouth disease. Some of the above and other viral infections cause purpuric rashes, which may be more severe. Laboratory diagnosis is performed directly, by viral isolation, antigen detection or viral nucleic acid detection, the latter being the best approach; or serologically, by detection of specific IgM (providing rapid diagnosis) or seroconversion. Both methodological tools generally complement each other to improve diagnostic performance. Molecular characterization is an important laboratory procedure, especially for the measles and rubella viruses, in the context of the plan for the elimination of these diseases (AU)

Vigilancia microbiológica del sarampión y la rubéola en España. Red de laboratorios / Microbiological surveillance of measles and rubella in Spain. Laboratory network

El laboratorio es un elemento imprescindible en la vigilancia del sarampión y la rubéola, ya que los casos han de ser adecuadamente confirmados para poder estimar la incidencia de forma precisa, las cepas han de ser caracterizadas genéticamente para conocer el patrón de circulación de los virus y estudiar de forma completa los brotes y las cadenas de transmisión y la susceptibilidad de la población debe de ser determinada mediante encuestas de seroprevalencia. El diagnóstico de laboratorio de las infecciones agudas por estos agentes se basa en la detección de la respuesta inmune específica de clase IgM, que debe de complementarse con la detección del genoma del virus en exudado faríngeo y/u orina para poder alcanzar un rendimiento diagnóstico óptimo, especialmente si la recogida de las muestras es muy temprana. El genotipado de la cepa se realiza por secuenciación genómica de acuerdo a protocolos de referencia de la OMS. La vigilancia de laboratorio de sarampión y rubéola en España se estructura en forma de red, con laboratorios autonómicos de capacidades diferentes y un Laboratorio Nacional de Referencia (LNR), que es el Centro Nacional de Microbiología, que garantiza la disponibilidad de las técnicas en todo el territorio nacional, vela por la calidad de los resultados y representa a la Red Nacional en la Red Europea de laboratorios. El LNR está actualmente implantando nuevas herramientas de caracterización molecular basadas en regiones hipervariables del genoma para la caracterización de las cepas a nivel subgenotípico y su aplicación a la vigilancia (AU)

The Laboratory is a fundamental component on the surveillance of measles and rubella. Cases need to be properly confirmed to ensure an accurate estimation of the incidence. Strains should be genetically characterized to know the transmission pattern of these viruses and frequently, outbreaks and transmission chains can be totally discriminated only after that. Finally, the susceptibility of the population is estimated on the basis of sero-prevalence surveys. Detection of specific IgM response is the base of the laboratory diagnosis of these diseases. It should be completed with genomic detection by RT-PCR to reach an optimal efficiency, especially when sampling is performed early in the course of the disease. Genotyping is performed by genomic sequencing according to reference protocols of the WHO. Laboratory surveillance of measles and rubella in Spain is organized as a net of regional laboratories with different capabilities. The National Center of Microbiology as National Reference Laboratory (NRL), supports regional laboratories ensuring the availability of all required techniques in the whole country and watching for the quality of the results. The NRL is currently working in the implementation of new molecular techniques based on the analysis of genomic hypervariable regions for the strain characterization at sub-genotypic levels and use them in the surveillance (AU)

Rubella specific cell-mediated and humoral immunity following vaccination in college students with low antibody titers.

OBJECTIVE: This study measured cell-mediated immunity (CMI) and antibodies to clarify the basis of rubella reinfection after vaccination. METHODS: In a pool of 65 college students, 39 who exhibited hemagglutination-inhibition (HI) antibody titers against rubella of ≤ 1:16 were vaccinated with a rubella vaccine. The CMI was assessed with interferon-gamma release assay. RESULTS: There was low correlation (r = 0.24) between the antibody titers and interferon-gamma levels at pre-vaccination status. Preexisting interferon-gamma levels were low in some subjects with low HI antibody titers of 1:8 and 1:16. Fifty-seven percent (4/7) of the subjects who were antibody-negative with past history of rubella vaccination at entry onto the study exhibited CMI. And 57% (4/7) of the subjects remained antibody-negative following a second vaccination, despite exhibiting CMI. HI antibody titers increased significantly after vaccination, whereas post-vaccination interferon-gamma levels did not exhibit significant increases. When subjects were divided (based on their past history of vaccination and antibody values) into natural infection and vaccination groups, HI antibody titers (mean ± SD) increased to 1:2(4.4 ± 1.4) from 1: 2(3.2 ± 0.4) (p = 0.065) in the natural infection group and to 1:2(4.4 ± 1.0) from 1:2(3.0 ± 0.8) (p < 0.00001) in the vaccination group following vaccination. The same classification revealed that interferon-gamma values did not increase significantly in either group following vaccination, but the interferon-gamma values at pre- and post-vaccination in the natural infection group were significantly higher than those at pre- and post-vaccination in the vaccination group (p < 0.05 and p < 0.05, respectively). CONCLUSION: Pre-vaccination interferon-gamma levels in each HI antibody titer group were similar. And there were some subjects with antibody-positive exhibited CMI-negative. These data may explain why rubella reinfection can occur in vaccinated seropositive individuals.

Rubella and measles seroprevalence among women of childbearing age, Argentina, 2002.

To assess rubella and measles susceptibility among women of childbearing age we conducted a cross-sectional seroprevalence study in four cities and one rural area in Argentina. A convenience sample of women aged 15-49 years seeking care in public health-care institutions was selected (n=2804). Serum specimens were tested for rubella and measles IgG antibody titres. The overall susceptibility to rubella and measles was 8.8 and 12.5% respectively. Seroprevalence differences were found for both rubella (P<0.001) and measles (P=0.002) across sites. Rubella seroprevalence was higher in women aged >or=40 years than in younger women (P=0.04). Measles seroprevalence tended to increase with age (P<0.001). Approximately 15% of women aged 15-29 years were not immune to measles. No risk factors were associated with rubella seronegativity; however, age (P<0.001) and having less than four pregnancies (P<0.001) were factors associated with measles seronegativity. Our findings support the introduction of supplemental immunization activities targeting adolescents and young adults to prevent congenital rubella syndrome and measles outbreaks over time.

[Staphylococcal colonization of the oral cavity of children following an acute form of rubella infection]. / Kolonizatsiia stafilokokkami polosti rta u detei, perenesshikh ostruiu formu krasnushnoi infektsii.

The children were being observed during the course of acute rubella infection and postinfectious period. Quantitative dynamic changes in the normal microflora composition were noted weekly during the first month of the disease as well as in the beginning of the second and the third months. The amount of microorganisms registered 3 weeks and in the beginning of the second month after the onset of rubella infection differed from that in the controls. The identification of the Staphylococcus genus microorganisms has shown an increased number of carriers during the first week, as well as on the third week from the onset of the disease. During these periods a secondary immunodeficiency is supposed to develop in children resulting in exacerbation of bacterial infections.

[Study on the relationship between the history of abnormal pregnancy and TORCH infection in pregnant woman].

OBJECTIVE: To investigate the relationship between the history of abnormal pregnancy and the Toxoplasma(TOX), Other(OTH), Rubella virus(RUV), Cytomegalo virus(CMV), Herpes simplex virus-II (HSV-II) (TORCH) infections in pregnant woman. METHODS: Enzyme-Linked immunosorbent assay(ELISA) combined with polymerase chain reaction (PCR) technique were used to detect TORCH infection in pregnant women with histories of abnormal pregnancies(study group, n = 54) and normal pregnant women (control group, n = 54). The fetal cord blood samples were also detected. RESULTS: In study group, the rates of previous TORCH infection: CMV 46.29%, RUV 16.29%, TOX 16.67%, HSV-II 29.63%. The rates of active infection: CMV 57.40%, RUV 59.26%, TOX 38.89%, HSV-II 46.29%. The rates of recurrent infection: CMV 38.89%, RUV 38.89%, TOX 11.11%, HSV-II 22.22%. These three kinds of infection rates in study group were significantly higher than that of control group (P < 0.01). The abnormal pregnant cntcomes in study group were significantly higher than that of control group(P < 0.01). The incidence of maternal-fetal vertical transmission in study group was 73.08%. CONCLUSION: TORCH series infection is one of the important causes of abnormal pregnant cutcomes. It is absolutely necessary to screen TORCH infection for women who had the histories of abnormal pregnancies in order to prevent birth defects and perinatal complications. ELISA combined with PCR technique is a valuable method for the diagnosis of TORCH infection.

Laboratory testing in patients with morbilliform viral eruptions.

The explosion of immunologic testing capabilities over the past 20 years has enabled clinicians to accurately diagnose many conditions that previously were very difficult to identify solely on a clinical basis. Among these disorders are the viral exanthems. Infections with some of these viruses are of relatively little import (erythema infectiosum), whereas others have more significant consequences (HIV, cytomegalovirus). Clinical suspicions may be pursued more fully now, sometimes even in an office setting.

Identification of strain-specific nucleotide sequences in the RA 27/3 rubella virus vaccine.

A polymerase chain reaction-based protocol was developed for determination of the sequence of 1300 nucleotides in the E1 coding region of the genomes of multiple strains of rubella virus. From a collection of sequences of 9 independent strains and isolates, characteristic nucleotides were identified that distinguished the RA 27/3 strain, which is the currently used attenuated vaccine strain. These characteristic nucleotides were maintained in virus recovered from recent vaccinees. Both the assay and the knowledge of these characteristic nucleotides should be of use in determining the origin of virus isolated from individuals who have suspected vaccine-associated complications. The nucleotide sequences of the independent rubella virus strains differed by 0.7%-3.6%. Phylogenetic tree analysis of the sequences indicated the existence of at least three distinct genetic lineages.

The placenta and viral infections.

Many viruses can infect the fetus in utero, by either ascending or hematogenous routes. Much is known about the maternal-fetal passage of virus from clinical, virologic, and serologic studies. Although transplacental passage is a key aspect of these infections, there is much more limited information about changes in the placenta. For a few infections, placental characteristics have been well described, and there is now increasing information on many others. Newer techniques for in situ demonstration of viruses will hopefully yield much information about diagnosis and the mechanisms of transplacental passage.

Comparative study of different methods for extraction of Rubella haemagglutinin from infected cells BHK-21.

The results from a comparative study of some methods for extraction of Rubella haemagglutinin from infected BHK-21 cells are presented. The best haemagglutinin extraction was achieved after the cells were treated with Tween 80-ether. The combined application of alkaline extraction and Tween 80-ether treatment also gave good results.

[Maternal viral infections as a fetal risk factor]. / Infekcje wirusowe u matki jako czynnik zagrozenia plodu.

After a review of the literature reports from recent years viral infections in pregnant women are presented as a fetal and neonatal risk factor. Maternal infections with rubella virus, cytomegalovirus++, hepatitis, Coxsackie B, varicella, herpes, poliomyelitis, parvovirus B19 and HIV are discussed stressing their unfavourable effect on the developing embryo, fetus or newborn.

Intrauterine diagnosis of cytomegalovirus and rubella infections by amniocentesis.

OBJECTIVE: To establish a correlation between the presence of cytomegalovirus (CMV) or rubella virus in amniotic fluid obtained through amniocentesis and fetal infection. DESIGN: Case series. SETTING: Five hospitals in the Montreal region. Virology testing was done at the Virology Research Centre, Institut Armand-Frappier, Laval, Que. PATIENTS: Thirteen pregnant women infected with CMV, 3 with rubella, their 15 babies and 2 fetuses. Twelve of the women with CMV infection were recruited from a prospective study of CMV infection in pregnancy. Infection in the other women was detected through routine laboratory diagnostic testing. INTERVENTION: Amniotic fluid samples were cultured for CMV and rubella virus. Congenital infection of the neonates was established through isolation of either virus from pharyngeal mucus and urine specimens collected during the first 3 days of life or from fetal tissue if the pregnancy was terminated. MAIN RESULTS: CMV was cultured from the amniotic fluid of three of the CMV-infected women and from the pharyngeal mucus and urine specimens of their infants. Of the three women with rubella the amniotic fluid of one (who had a twin pregnancy) was positive for rubella virus. After the in-utero death of one fetus she underwent a therapeutic abortion of both. Examination of fetal tissue indicated that both fetuses had been infected with rubella virus. Each of the two other women with rubella gave birth to an uninfected, healthy infant. CONCLUSIONS: We found a strong correlation between the isolation of CMV or rubella virus from the amniotic fluid and the presence of congenital infection. This suggests that amniocentesis used to detect the presence of a virus is a useful method for the diagnosis of fetal infection.

Rubella-specific IgG1 avidity: a comparison of methods.

Two methods of determining the avidity of specific IgG1 were compared with sera from different categories of rubella infection. Both methods were based on an antiglobulin enzyme-linked immunosorbent assay. In one method the absorbances were compared with and without diethylamine (DEA) in the serum diluent over a range of serum dilutions and the difference between the dilution curves measured (DEA-shift). In the other, the absorbances at a single serum dilution were compared with and without urea in the wash fluid used after the antigen/serum incubation (avidity index). Various concentrations of DEA were also assessed in the avidity-index method, as this method is simpler to perform. The DEA-shift method was shown to be more sensitive for diagnosing recent primary rubella or immunization by demonstrating specific IgG1 of low avidity. The avidity-index method, however, was more specific when sera from cases of reinfection or non-specific rubella IgM reactivity were tested. 35 mM DEA was found to be the optimal concentration of DEA when DEA was substituted for urea in the avidity index method.

Late-onset rubella syndrome: coexistence of immune complex disease and defective cytotoxic effector cell function.

We studied a classical case of late-onset rubella syndrome characterized by multi-organ disease and persistence of live rubella virus in spite of high titres of specific antirubella antibodies and presence of large amounts of circulating immune complexes. When first studied at the age of 5 months there was a low proportion of T8+ lymphocytes. Functional studies revealed decreased activity of K and NK cells as well as alloreactive direct cytotoxic cells (CTL). Removal of cell-bound immunoglobulin and immune complexes tended to improve K and NK cell function in vitro. Plasma exchange transfusions carried out at 9 months of age resulted in clinical improvement. Normalization of cytotoxic effector cell functions and cessation of viremia accompanied recovery from active disease. The results indicate that defective cytotoxic effector cell function is the primary cause for the defective virus elimination in this syndrome.

Viremia, virus excretion, and antibody responses after challenge in volunteers with low levels of antibody to rubella virus.

After intranasal challenge of volunteers with rubella virus vaccine, viremia was assayed by inoculation of lymphocytes and whole blood from vaccines into Vero cell cultures. Viremia was detected in one of 19 volunteers with low levels (less than or equal to 15 IU) of preexisting vaccine-induced antibody to rubella virus, in eight of 10 seronegative volunteers, in none of 10 seropositive volunteers (antibody level, greater than 15 IU), and in none of 12 volunteers with low levels of preexisting naturally acquired antibody. Excretion of the virus was detected in four volunteers with preexisting vaccine-induced antibody but in none with naturally acquired antibody; eight of 10 seronegative volunteers excreted virus. After challenge, all volunteers with low levels of preexisting vaccine-induced antibody developed booster antibody responses that were measured by radioimmunoassay, and low levels of rubella-specific IgM were detected in four volunteers by M-antibody capture radioimmunoassay. One seronegative, one seropositive, and five low-titer volunteers developed arthralgia. The risk of viremia after challenge in individuals with low levels of rubella antibody appears to be low but may be higher than usual when immunity is induced by rubella vaccine.