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Biomedical subjects

R T Mayon-White

Publications and source records attributed to R T Mayon-White.

At least 19 recordsLinked to original sources

The impact of HIV on maternal quality of life in Uganda.

To study the effect of HIV infection on quality of life (QOL) during pregnancy and puerperium, QOL was measured in a cohort study at St. Francis Hospital Nsambya, Kampala, Uganda. Dartmouth COOP charts were administered to 132 HIV-positive and 399 HIV-negative women at 36 weeks of pregnancy and six weeks post-partum. Responses were coded from 0 = best health-status to 4 = worst health-status and scores of 3-4 defined as poor. Odds ratios (OR) (95% confidence intervals(CI)) for poor scores were calculated and independent predictors of poor QOL examined using logistic regression. In pregnancy, HIV-positive women were more likely to have poor scores in feelings: OR = 3.2(1.9-5.3), daily activities: OR = 2.8(1.4-5.5), pain: OR = 2.1(1.3-3.5), overall health: OR = 1.7(1.1-2.7) and QOL: OR = 7.2(3.6-14.7), all p= 0.2). HIV infection was independently associated with poor QOL: OR = 8.5(3.8-19). Findings in puerperium were similar to those in pregnancy except more HIV-positive women had poor scores in social activities: OR = 2.5(1.4-4.7) and change in health: OR = 5.4(2-14.5) and infant death also predicted poor QOL: OR = 6.7(2.4-18.5). The findings reflect HIV's adverse impact on maternal QOL and the need for interventions to alleviate this infection's social and emotional effects.

Adult↗

Audit of antibiotic policies in the South East of England, 2004.

OBJECTIVES: The antibiotic policies of hospitals and primary care trusts (PCTs) in South East England were audited in the summer of 2004, to see how they had improved since 2000. METHODS: Antibiotic policies were obtained from pharmacists in NHS hospitals and PCTs, and examined for dates, formats, evidence base for policies, the type of guidance given on dosage, length of treatment, choice of antibiotics, coverage of common infections and reasons for prophylaxis. RESULTS: Twenty-three hospital and 25 primary care policies were examined. The average age of policies was 12 months, but 13 were more than 2 years old. The commonest format was an A4-sized document available in an electronic version. Primary care policies were more uniform than hospital policies. More primary care than hospitals' policies gave evidence to support their guidance. Ten policies used plain English for dosages, and 38 (79%) policies made few or no cautionary points about the drugs recommended. Respiratory and urinary infections were covered in most policies, but guidance on gastroenteritis and antibiotic prophylaxis was less frequent. There was little advice in the policies on the management of methicillin-resistant Staphylococcus aureus. CONCLUSIONS: Primary care policies have improved since 2000, using a national model for evidence and a consistent style. Hospitals could benefit from similar national guidance, especially in the evidence to support the contents of antibiotic policies.

Anti-Bacterial Agents↗

A survey of hepatitis C prevalence amongst the homeless community of Oxford.

Hepatitis C (HCV) is an emerging health concern across the world, with 170 million people chronically infected and at risk of liver cancer, cirrhosis or liver failure. There is no vaccination and so it is important to learn as much as possible about how to prevent future infection. Modes of transmission include intravenous drug use (IDU), blood products, tattooing and, to a lesser extent, sexual intercourse. Homelessness is a risk factor of HCV because of the environments and behaviours associated with homeless communities such as poor hygiene, poor nutrition and high levels of IDU. The aim of this project was to determine the prevalence of HCV and its risk factors amongst the homeless community of Oxford, which is the second largest in the country. Ninety-eight individuals of the Oxford homeless community were interviewed and tested for HCV. The results gave an estimated HCV prevalence of 26.5 percent. The major risk factors in this population were IDU (past and present), age (over 20 years old) and sharing the paraphernalia used by i.v. drug users (e.g. spoons, foil and filters). With the exception of age, these risk factors could all be targeted in an attempt to reduce this prevalence and combat the major public health concern that HCV poses to the homeless community of Oxford.

Adolescent↗

Invasive pneumococcal disease in England and Wales: vaccination implications.

Knowledge of the epidemiology of invasive pneumococcal disease (IPD) will aid in planning the use of pneumococcal vaccines. A United Kingdom (UK)-based surveillance in England and Wales (1995-1997) of 11,528 individuals with IPD and a local enhanced surveillance in the Oxford (UK) area (1995-1999) have been analyzed. IPD has a high attack rate in children, with 37.1-48.1 cases per 100,000 infants <1 year old per year, and in older persons, with 21.2-36.2 cases per 100,000 persons >65 years old per year, for England, Wales, and Oxford. The 7-valent conjugate vaccine includes serotypes causing < or =79% of IPD in children <5 years old, but only 66% in adults >65 years old. The data also indicate that IPD varies by serotype, age, and country, emphasizing that the epidemiology of IPD is heterogeneous and requires continued surveillance.

Adolescent↗

Diagnosis of viral infections of the central nervous system: clinical interpretation of PCR results.

BACKGROUND: Standard laboratory techniques, such as viral culture and serology, provide only circumstantial or retrospective evidence of viral infections of the central nervous system (CNS). We assessed the diagnostic accuracy of PCR of cerebrospinal fluid (CSF) in the diagnosis of viral infections of the CNS. METHODS: We examined all the CSF samples that were received at our diagnostic virology laboratory between May, 1994, and May, 1996, by nested PCR for viruses associated with CNS infections in the UK. We collected clinical and laboratory data for 410 patients from Oxford city hospitals (the Oxford cohort) whose CSF was examined between May, 1994, and May, 1995. These patients were classified according to the likelihood of a viral infection of the CNS. We used stratified logistic regression analysis to identify the clinical factors independently associated with a positive PCR result. We calculated likelihood ratios to estimate the clinical usefulness of PCR amplification of CSF. FINDINGS: We tested 2233 consecutive CSF samples from 2162 patients. A positive PCR result was obtained in 143 patients, including 22 from the Oxford cohort. Logistic regression analysis of the Oxford cohort showed that fever, a virus-specific rash, and a CSF white-cell count of 5/microL or more were independent predictors of a positive PCR result. The likelihood ratio for a definite diagnosis of viral infection of the CNS in a patient with a positive PCR result, relative to a negative PCR result, was 88.2 (95% CI 20.6-378). The likelihood ratio for a possible diagnosis of viral infection of the CNS in a patient with a negative PCR result, relative to a positive PCR result, was 0.10 (0.03-0.39). INTERPRETATION: A patient with a positive PCR result was 88 times as likely to have a definite diagnosis of viral infection of the CNS as a patient with a negative PCR result. A negative PCR result can be used with moderate confidence to rule out a diagnosis of viral infection of the CNS. We believe that PCR will become the first-line diagnostic test for viral meningitis and encephalitis.

Adolescent↗

A study of 42 episodes of overwhelming post-splenectomy infection: is current guidance for asplenic individuals being followed?

Individuals without a spleen have an increased risk of overwhelming post-splenectomy infection (OPSI). Improved awareness in recent years has stimulated increased efforts to prevent OPSI. Published guidelines have described policies for immunization, chemoprophylaxis and other measures considered beneficial to asplenic patients, yet OPSI episodes continue to occur. In an attempt to investigate why serious infections are still being seen, we have conducted a nationally based survey of recent OPSI episodes, using mainly a network of medical microbiologists. Data including clinical background to both splenectomy and OPSI episode, immunization and chemoprophylaxis history have been collated. Forty-two cases of overwhelming infection were reported by June 1996. Patients of all ages were affected with OPSI occurring up to 59 years after splenectomy. A mortality rate of 45% was seen. Pneumococcal infection caused at least 37 of 42 episodes, but only 12 patients had received pneumococcal vaccine. Four cases were possible vaccine failures. Only 22% of individuals had taken any chemoprophylaxis since splenectomy, and only one carried a medical alert card. Much more needs to be done to ensure that asplenic patients are warned of the risks of infection, and given at least pneumococcal vaccine. The role of antibiotics for either continual prophylaxis or as a reserve supply for self-prescription at appropriate times also needs greater discussion. Further work on improving pneumococcal vaccine response together with suitable programmes for revaccination are required. Surveillance should continue until the incidence of OPSI reaches an irreducible minimum.

Adult↗

Meningococcal vaccines for the United Kingdom.

New meningococcal vaccines are needed in the United Kingdom with some urgency. Almost all Neisseria meningitidis disease in this country is caused by serogroups B and C. Infants have the highest attack rates, but also make the poorest immunological responses to potential vaccines. The development of vaccines that protect infants is a significant challenge. A capsule-based serogroup B vaccine is unlikely to be successful in infants because the capsule is poorly immunogenic and the polysaccharide molecule mimics a human epitope. Without completely discounting capsule as an immunogen, alternate antigens are being considered for immunisation: outer membrane proteins (OMP), iron regulating proteins, and lipopolysaccharide. Vaccines based on OMP have been used in several phase 3 trials in South Africa, Cuba, Brazil, Norway, and Chile, in which two doses of vaccine were given. The Cuban and Norwegian vaccines have been compared in phase 2 trials in Iceland and Chile. Potential limitations are epitope heterogeneity and the theoretical ability of N. meningitidis to adapt even to hosts who have received polyvalent vaccines. A phase 2 trial of a hexavalent class 1 OMP vaccine is under way in Gloucester, with 100 babies receiving injections at 2, 3, and 4 months. Serogroup C vaccines have been developed from capsular polysaccharide but, unconjugated, these vaccines do not protect those under 2 years of age. Conjugate vaccines with C and AC polysaccharides are immunogenic in infants, but antibody titres may wane quickly.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Vaccines↗

The impact of conjugate vaccine on carriage of Haemophilus influenzae type b.

Conjugate vaccines against Haemophilus influenzae type b (Hib) may modify Hib pharyngeal colonization. Hib colonization was compared in 371 infants and their families. In Oxfordshire, infants received PRP-T (polyribosylribitol phosphate conjugated to tetanus toxoid) and in Buckinghamshire they did not (controls). Infants were followed at 6, 9, and 12 months of age. Also, 6 unvaccinated Hib carriers were vaccinated and followed for 6 weeks. Hib acquisition was lower in vaccinees than controls (P < .01). During surveillance, 1.5% of vaccinees and 6.3% of controls carried Hib (P = .04). Among those with family Hib exposure, the carriage rates were 8.7% and 38.5% (P = .07), respectively. Hiv carriage rates were lower among vaccinees' unvaccinated siblings. Giving conjugate vaccine to a child carrying Hib did not rapidly terminate carriage. Thus, a primary means by which herd immunity to Hib is induced in a vaccinated population may be through reduction or delay in the initial acquisition of Hib.

Bacterial Capsules↗

Efficacy of Haemophilus influenzae type b conjugate vaccine PRP-T.

Efficacy of the Haemophilus influenzae type b (Hib) conjugate vaccine PRP-T (Pasteur-Merieux) was evaluated in a controlled community intervention study in the Oxford region, UK. PRP-T was offered to infants from May 1, 1991 in three of the region's eight districts and from July 1, 1991, in a fourth district. It was given by separate injection in addition to the standard diphtheria, tetanus, and pertussis vaccine according to an accelerated 2, 3, and 4 month schedule without a booster dose in the second year of life. By October 1, 1992, more than 90% of infants in vaccine districts had received at least one dose of PRP-T. None of the infants given three doses had developed Hib infection, whereas 11 infections occurred in the control population (vaccine efficacy 100%, 95% CI 80-100%). Intention-to-treat analysis also showed a high estimate of efficacy for the vaccine (90%, 50-99%). Follow-up of study children until November 1, 1993, has shown only 1 vaccine failure in an infant, and no invasive infections in those older than 1 year (average age 22 months). PRP-T vaccine had high protective efficacy with an accelerated immunisation schedule. Furthermore, the vaccine appears to remain protective through the second year of life without a booster dose. These findings provide encouragement for use of PRP-T in the Expanded Programme of Immunisation.

Child, Preschool↗

Tempting fate: control of communicable disease in England.

Recent changes in the NHS have left many defects in the systems for the control of communicable diseases and infection and their surveillance and the management of outbreaks. Clear, explicit legislation is needed, placing the responsibilities on health authorities. New teams led by consultants need to be set up to investigate and manage outbreaks of communicable diseases of all types.

Communicable Disease Control↗

An improved antiserum agar method for detecting carriage of Haemophilus influenzae type b.

Enriched Columbia medium was tested against Levinthal medium for the isolation of Haemophilus influenzae type b. In both media, Haemophilus influenzae type b recovery and antigen-antibody precipitation halos were equivalent. Haemophilus influenzae type b colony size and iridescence were superior on enriched Columbia medium. Enriched Columbia medium is inexpensive, simply prepared and easily standardised.

Agar↗