Persistence of varicella-zoster virus viraemia in patients with herpes zoster.

BACKGROUND: Herpes zoster is caused by the reactivation of varicella-zoster virus from sensory neurons. The commonest complication following zoster is chronic pain termed post herpetic neuralgia. OBJECTIVES: To investigate the dynamics of VZV viraemia and viral load following the resolution of zoster and its relationship to PHN development. STUDY DESIGN: Blood samples were collected at baseline, 1 month, 3 months and 6 month from a prospective study of 63 patients with active zoster. Quantification of VZV DNA in whole blood was performed using a real-time PCR assay. RESULTS: During acute zoster, all patients had detectable VZV DNA in their blood. VZV DNA remained detectable in the blood of 91% of patients at 6 months although levels declined significantly (p<0.0001). A history of prodromal symptoms (p=0.005) and severity of pain at baseline (p=0.038) as well as taking antivirals (p=0.046) and being immunocompromised (p=0.043) were associated, with longer time to recovery from PHN. Viral DNA loads were consistently higher in patients with risk factors for PHN and higher viral DNA loads over time were associated with longer time to recovery (p=0.058 overall and 0.038 in immunocompetent). CONCLUSIONS: Based on these observations we hypothesise that VZV replication persists following acute shingles and that higher viral DNA loads contribute to the risk factors for PHN.

The seroepidemiology of varicella zoster virus among pregnant Bangladeshi and white British women in the London Borough of Tower Hamlets, UK.

We investigated the comparative seroepidemiology of varicella zoster virus (VZV) in pregnant women of two ethnic groups, white British and Bangladeshi, living in an inner city area of London, United Kingdom. Women aged 16-45 years were recruited from antenatal clinics of the Royal London Hospital in the Borough of Tower Hamlets. Complete data were obtained from 275 white British and 765 Bangladeshi women. VZV antibody prevalence was 93.1% (95% CI 89.4-95.8) and 86.0% (95% CI 83.3-88.4) respectively. Women who were born in Bangladesh and lived there at least until the age of 15 years had the lowest odds of being immune (OR 0.37, 95% CI 0.22-0.63). This implies they will have an increased risk of varicella during pregnancy. Women arriving in the United Kingdom in adulthood should be screened routinely during pregnancy and vaccination offered postpartum if they are susceptible.

Genotyping of varicella-zoster virus and the discrimination of Oka vaccine strains by TaqMan real-time PCR.

Single nucleotide polymorphisms (SNPs) in five genes have been used to identify four major subtypes of wild-type varicella-zoster virus (VZV) A, B, C, and J. Additional SNPs, located in the IE62 major transactivating gene can be used to differentiate the Oka vaccine strain (vOka) from wild-type VZV. Primer-probe sets for the detection of the five polymorphic loci were designed by Applied Biosystems for the ABI 7900HT platform. Probes for each allele were labeled with VIC or 6-carboxyfluorescein fluorogenic markers. Each primer-probe set was validated to establish assay sensitivity and specificity using VZV DNA of predetermined copy number and genotype. Further evaluation was carried out using DNA samples from the vesicle fluid or skin swab of the rash of adult patients with herpes zoster or rashes due to vOka. Assay sensitivity ranged from 10 and 10(8) copies/ml of VZV DNA (equivalent to 2 to 20 copies per reaction). Statistical analyses showed that for each genotype, a set of two probes clearly differentiated the nucleotide present (allele) at that locus (P < 0.0001). It was possible to determine the genotype of wild-type VZV using one of four SNP assays and also to differentiate wild type from vOka using a single SNP assay. The assay can be used for diagnostic and epidemiological studies of VZV, including the differentiation of vOka from wild-type strains, investigation of breakthrough infections, and varicella outbreaks following immunization.

Reactivation of 2 genetically distinct varicella-zoster viruses in the same individual.

Varicella-zoster viruses recovered from 2 episodes of herpes zoster in an immunocompetent man were found to be different genotypes. The fact that the 2 isolates came from the same individual was confirmed by DNA fingerprinting. Immunity following chickenpox may not always protect against systemic reinfection. This finding raises questions about varicella-zoster virus pathogenesis and may have an impact on public health policy.

Comparative studies of human rotavirus serotype G8 strains recovered in South Africa and the United Kingdom.

Epidemiological studies on the VP7 serotype prevalence of human rotaviruses in South Africa and the United Kingdom identified several strains which could not be serotyped as G1-G4 by monoclonal antibodies. Further analysis of these strains with a G8-specific monoclonal antibody and with probes for human rotaviruses confirmed them as G8 rotaviruses. These G8 strains exhibited a high degree of sequence identity when compared with each other and with other rotavirus G8 strains. Five South African strains were further characterized as VP6 subgroup I, but with a long RNA electropherotype, which is similar to the G8 strains previously isolated in Finland. In the UK strains, one was VP6 subgroup II with a long RNA electropherotype (similar to the Italian G8 strain). The other two were subgroup I with a short RNA electropherotype. None of these strains exhibited the super-short RNA electropherotype described in the prototype G8 strains recovered from Indonesia (69M).

Incidence of symptomatic toxoplasma eye disease: aetiology and public health implications.

Ocular disease is the commonest disabling consequence of toxoplasma infection. Incidence and lifetime risk of ocular symptoms were determined by ascertaining affected patients in a population-based, active reporting study involving ophthalmologists serving a population of 7.4 million. Eighty-seven symptomatic episodes were attributed to toxoplasma infection. Bilateral visual acuity of 6/12 or less was found in seven episodes (8%) and was likely to have been transient in most cases. Black people born in West Africa had a 100-fold higher incidence of symptoms than white people born in Britain. Only two patients reported symptoms before 10 years of age. The estimated lifetime risk of symptoms in British born individuals (52% of all episodes) was 18/100000 (95% confidence interval: 10.8-25.2). The low risk and mild symptoms in an unscreened British population indicate limited potential benefits of prenatal or postnatal screening. The late age at presentation suggests a mixed aetiology of postnatally acquired and congenital infection for which primary prevention may be appropriate, particularly among West Africans.

Detection of antibodies to hepatitis C virus in dried blood spot samples from mothers and their offspring in Lahore, Pakistan.

Dried blood spot samples from mothers and their offspring attending the obstetric and pediatric departments of two hospitals in Lahore, Pakistan, were tested for antibodies to hepatitis C virus (HCV). The seroprevalence of HCV in the women was 6.7% (95% confidence interval [CI], 4.3 to 9.1), and that in the children was 1.3% (95% CI, 0.34 to 2.26). Four anti-HCV immunoglobulin G (IgG)-positive children had mothers that were anti-HCV IgG negative, which suggested that their infection was community acquired.

Vitamin A, E and carotenoid status in Jamaica children with sickle cell disease

Nutritional deficiencies would appear to be an important determinant of morbidity in homozygous sickle cell (SS) disease. This is evidenced by the growth and development deficits which are observed in children with SS disease. In a study of the nutritional status of Jamaican children with SS disease aged 3 to 6 years, serum samples from blood taken after an overnight fast in the SS children and children of the same age with normal haemoglobin (AA) were collected. Micro-nutrient analyses of these serum samples for vitamin A (retinol) and vitamins E (alpha and gamma tocopherol) and the carotenoids, beta-carotene and lycopene were carried out using high performance liquid chromatography (HPLC). The results suggest that in children with SS disease several of the micro-nutrients which are essential for maintaining optimal antioxidant status are found in decreased amounts in serum. The confirmation of these micronutrients deficiencies in SS children provide the basis fo further exploration of their interrelationshipo with the growth and development deficits in this population. (AU)

A method for the detection and confirmation of antibodies to hepatitis C virus in dried blood spots.

This study describes the development and evaluation of a cost effective test rationale for the detection of anti-HCV in dried blood spots. Samples were screened using an 'in house' IgG ELISA that incorporated the recombinant proteins c22-3, c200 and NS5. Confirmation of specific antibody to HCV was by a modification of the immunoblot RIBA 3.0. An extensive panel of well evaluated anti-HCV positive and negative samples from the UK and South Africa were used to assess the sensitivity and specificity of the two tests. One third of the anti-HCV positive samples had been typed. All anti-HCV positive samples were detected by the 'in house' screening EIA. Test/negative optical density ratios showed that more than 95% of reactive samples produced values greater than 5.0. Antibodies to HCV could be detected in a wide range of samples derived from asymptomatic and symptomatic patients and of different genotypes, with similar sensitivity. The presence of anti-HCV could be confirmed by RIBA 3.0 in samples with low reactivity but not in anti-HCV negative samples. Furthermore the immunoblot assay successfully increased specificity by screening out false reactive EIA samples that might occur in an epidemiological survey of a multi-ethnic population.

PIP: While hepatitis C virus (HCV) is a major etiological agent of post-transfusion and community acquired non-A, non-B hepatitis, little is known about the epidemiology of HCV in the UK. A cost-effective method using dried blood spots to determine anti-HCV IgG in subjects which could be used in large-scale epidemiological studies is described. Samples were screened using an in-house IgG ELISA incorporating the recombinant proteins c22-3, c200, and NS5, while specific antibody to HCV was confirmed using a modified immunoblot RIBA 3.0. A panel of well evaluated anti-HCV positive and negative samples from the UK and South Africa were used to assess the sensitivity and specificity of the 2 tests. All anti-HCV positive samples were detected by the in-house screening EIA. Test/negative optical density ratios showed that more than 95% of reactive samples produced values greater than 5.0. Antibodies to HCV could be detected in a wide range of samples derived from asymptomatic and symptomatic patients and of different genotypes, with similar sensitivity. The presence of anti-HCV could be confirmed by RIBA 3.0 in samples with low reactivity, but not in anti-HCV negative samples. The immunoblot assay increased specificity by screening out false reactive EIA samples.

Seroepidemiology of HTLV-I in relation to that of HIV-1 in the Gauteng region, South Africa, using dried blood spots on filter papers.

The seroprevalence of human T-lymphotropic virus type I (HTLV-I), in relation to that of human immunodeficiency virus type I (HIV-1), was determined in a comparative unlinked anonymous antenatal and neonatal (for indirect measurement of maternal antibodies) serosurvey in the Gauteng region of South Africa, using dried blood spots (DBS) and modified particle agglutination assays. Samples were confirmed to be antibody positive by western blot. A total of 2582 DBS collected during 1993 and 1994 from subjects of African, European and coloured origin were tested. Ten were confirmed as positive for HTLV-I and 128 for HIV-1. No antibodies to HTLV-I or HIV-1 were demonstrated in the 221 women of European and coloured origin who were screened. The HTLV-I seroprevalence rate in subjects of African origin appeared to increase from 0% in 1993 to 0.49% in 1994, while HIV-1 seroprevalence rates of 5.2% and 5.4% were recorded for 1993 and 1994 respectively. No significant differences in HTLV-I and HIV-1 seroprevalence rates were noted for the two areas investigated. These results indicate that HTLV-I should be included in infection control programs, and provide baseline data for monitoring the possible spread of HTLV-I in the heterosexual population in this region.

PIP: Dried blood spots and modified particle agglutination assays were used to determine the seroprevalence of human T-lymphotropic virus type I (HTLV-I) in relation to that of HIV-1 in an unlinked antenatal survey conducted in South Africa's Gauteng region. Of the 2582 serosamples collected in 1993-94, 1259 were obtained from pregnant women attending an antenatal clinic at Soweto's Baragwanath Hospital and 1323 were prepared from cord blood (for indirect measurement of maternal antibodies) of infants delivered in Pretoria. Western blot analysis confirmed that 10 samples were positive for HTLV-I and 128 were positive for HIV-1. No antibodies to either infection were noted in the 221 women of European and Colored origin included in the screening. From 1993 to 1994, the HTLV-I seroprevalence rate among African women screened increased from 0% to 0.49% while that for HIV-1 increased from 5.2% to 5.4%. Seroprevalence rates in the Gauteng region in 1994 were 0.44% and 5.0%, respectively. These findings suggest that HTLV-I should be included in infection control programs in South Africa.

Effect of music training on monaural perception of pitch and rhythm.

A monaural study of music perception was conducted on 77 right-handed subjects from a university population. The musical ability of each subject was classified in two ways, according to years of training and by total score for three tests of musical achievement [melody (sequence and excerpt), harmony, and rhythm]. Analysis indicated that subjects with more years of training showed a right-car dominance for recognition of excerpts but those with high scores had no such dominance. Both groups with either low scores or no formal training had a right-ear dominance for recognition of sequences. Correlations of scores from each ear within subjects and between tests indicated that perception of pitch tended to be more accurate in the same car. For all classifications of subjects no ear dominance was found for harmony and rhythm tests. These results suggest that the measurement of hemispheric asymmetry of music perception is dependent upon the criteria chosen for classification of subjects, in this case, training and achievement.

Use of dried blood spots for the detection and confirmation of HTLV-I specific antibodies for epidemiological purposes.

AIMS--To modify and evaluate a gelatin particle agglutination test that could provide a sensitive, specific and inexpensive method for the detection of HTLV-I antibody in dried blood spot samples (DBS) collected on filter paper. METHODS--A set of 26 reference samples confirmed as HTLV-I antibody positive were assembled from patients with tropical spastic paraparesis or adult T cell leukaemia and blood donors. Serum samples and simulated antibody positive dried blood spot eluates were tested using the Serodia assay together with two confirmatory tests: HTLV BLOT 2.3, a western blot, and Select-HTLV, an enzyme immunoassay (EIA). Both confirmatory tests use synthetic peptides to differentiate between antibodies to HTLV-I and -II. The modified Serodia assay was then used to test anonymously 10,135 DBS collected from neonates from London. Samples reactive in the modified Serodia test producing a positive result were titrated to an end point and confirmed as before. RESULTS--All 26 eluates made from simulated DBS derived from positive reference samples were identified as positive by the modified Serodia HTLV-I test and were confirmed as anti-HTLV-I positive by EIA. Two eluates derived from relatively low titre reference samples gave indeterminate results on western blotting. Screening of the 10,135 neonatal DBS resulted in six repeat reactives, five of which were confirmed. The remaining reactive sample gave an indeterminate result on western blotting and there was insufficient eluate for testing by EIA. The overall seroprevalence of HTLV-I in this population was 0.05% (five of 10,135). CONCLUSION--The modified Serodia HTLV-I assay provides a sensitive, specific and inexpensive (10 pence/test) method for screening large numbers of DBS. The format of the assay makes it ideally suited for simultaneous screening of antibodies to HIV-1, HIV-2 and HTLV-I using semi-automated equipment.

Enzyme immunoassay using baculovirus-expressed human calicivirus (Mexico) for the measurement of IgG responses and determining its seroprevalence in London, UK.

The use of an enzyme immunoassay (EIA) employing a baculovirus-expressed recombinant human calicivirus (Mexico virus, MxV) for the detection of IgG-specific antibodies is described. MxV appeared to be related antigenically to a strain of small round structured virus, SRSV/UK4/Leeds/91, which had previously been shown by solid phase immune electron microscopy (SPIEM) to be related to Snow Mountain agent (SMA). One other outbreak which occurred in San Anita, USA in 1980 and was due to consumption of contaminated water was caused by a virus antigenically related to MxV. Volunteers and patients who developed significant IgG responses to rMxV showed anamnestic IgG responses (2 to 4-fold) in the recombinant Norwalk virus (rNV) IgG assay. Patients and volunteers who were known to have been infected with several other strains of calicivirus/small round spherical viruses (SRSV) including NV and SRSV UK3 showed no significant antibody response to rMxV in the EIA. A seroepidemiological survey of sera from 338 children in London showed that infection with MxV occurred earlier in life than NV. Primary infections with MxV were common after the age of 6 months. Over 70% of children had evidence of infection by the ages of 2 years, whereas only 12% of these children had been infected with NV. High concentrations of maternal antibody were present during the first month of life which was detected in 96% of the neonates. The results suggest that the high sensitivity of the EIA may be detecting maternal antibody throughout the first 8 months of life.

Subdural empyema in an HIV positive patient.

A subdural empyema with a Salmonella species as the likely causative organism is presented. We believe that this is the first reported case of such an infection in an HIV positive patient. The difficulties in treatment and diagnosis are discussed.

Measurement of IgA responses following Norwalk virus infection and other human caliciviruses using a recombinant Norwalk virus protein EIA.

An enzyme immunoassay employing recombinant Norwalk virus capsid protein was evaluated for the measurement of IgA responses. Tests on 23 volunteers and patients known to have been infected with Norwalk virus (NV) showed that 19 developed significant IgA responses, 2 had unchanging levels of IgA and 2 failed to respond. There was no evidence of IgA responses to NV following infection with Hawaii or Snow Mountain-like viruses. Tests on sera from patients involved in outbreaks associated with eating contaminated shellfish suggest that some patients may have been infected with more than one strain of calicivirus. The use of the rNV EIA for measuring IgA and IgG responses in patients involved in a major outbreak of food poisoning affecting hospital staff indicated that the causative agent was probably NV.

Seroprevalence studies using a recombinant Norwalk virus protein enzyme immunoassay.

A recombinant Norwalk virus (NV) protein enzyme immunoassay was used to study the age of acquisition of NV IgG in various populations. In London, England, there was little evidence of infection during the first 2 years of life. However, the prevalence of NV IgG rose steadily throughout the period that children attend school, reaching a peak of 70% in the group aged 11-16 years. High levels of maternal antibody were detected in infants aged < 3 months. Comparison of the acquisition of antibodies to three strains of human calicivirus in Japanese children in northern Japan indicated that although the majority had experienced infection with strains Japan and UK1 by the age of 12 years, only 22% possessed antibodies to NV. In Australian aborigines NV infection occurs early in life; by the age of 6 years over 90% of children were seropositive.

Impact of rotavirus infection on a paediatric hospital in the east end of London.

AIMS: To study the impact of confirmed rotavirus infection at a paediatric hospital; to use the data to obtain a minimum estimate of the cost of treating reported cases of rotavirus in England and Wales. METHODS: Data were obtained on all patients with rotavirus over a two year period. Information was collected on 386 patients with rotavirus infection who were treated at the 120 bed Queen Elizabeth Hospital for Children in East London. This included the virus serotype, the patient's age, whether they required intravenous infusion, duration of hospital stay, numbers of patients treated in the casualty department, and numbers who had to be admitted. Treatment costs were obtained from the Finance Department of the Hospitals for Sick Children. RESULTS: The minimum cost of treating patients, excluding the cost of medical staff at the hospital, was estimated to be 95,400 pounds a year. One hundred and forty eight (38%) patients were admitted to the wards and a further 49 patients developed symptoms while in hospital. Intravenous infusion was required by 18 patients. The mean duration of hospital stay was 5.5 days. One hundred and eighty nine (49%) patients were treated with oral rehydration solution in casualty, given advice, and sent home. Ninety four per cent of the patients were aged under 2 years. The findings were comparable with those obtained in a study at Texas Children's Hospital, USA. The G serotype (VP7) of rotavirus did not influence the severity of infection. CONCLUSION: Rotavirus infections accounted for a significant number of patients treated in casualty, admissions to hospital, and bed occupancy in a paediatric hospital. The estimated cost of treating reported cases of rotavirus in England and Wales is in excess of 6.3 pounds million a year.

Modified latex agglutination test for antibodies to Toxoplasma gondii in eluates from Guthrie cards.

AIMS: To determine whether the Eiken particle agglutination test could be modified to make it sufficiently sensitive to screen blood samples collected on Guthrie cards for the presence of antibodies to Toxoplasma gondii; to evaluate the specificity of the modified system; and to compare seroepidemiological data on the prevalence of T gondii in pregnant women. METHODS: Simulated dried blood spots were prepared from sera from pregnant women booking for antenatal care. Eluates from the simulated dried blood spot cards and sera were tested in parallel using the modified test (1 in 5 dilution of latex) and the standard assay (neat latex particles) and endpoints determined. Guthrie card eluates, from neonates in three Thames regions, were then tested using the modified test. RESULTS: The modified test produced a 4.21-fold increase in antibody titre in 85 sera when tested in parallel with the standard test. Eluates of 168/170 from simulated dried blood spots derived from seropositive patients gave a positive result in the modified test. The two eluates which gave a negative result were derived from patients with an equivocal titre of 1/16 in the standard serum test. Of the eluates derived from serum negative patients all 103 were negative at a dilution of 1 in 4 in the modified test. The seroprevalence of antibodies to T gondii in pregnancy was 21.8% using the standard test. A similar value of 20.5% was obtained when dried blood spots from neonates in a similar region of London were tested by the modified test. CONCLUSIONS: The modified Eiken Toxo-reagent test is sensitive, simple, and economic for screening large numbers of dried blood spots. The procedure could be easily semiautomated and the technique applied to the mass screening of neonatal blood samples collected on Guthrie cards to determine the seroprevalence of T gondii in pregnant women.