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Biomedical subjects

K R Neal

Publications and source records attributed to K R Neal.

At least 37 records · Page 2Linked to original sources
PubMed2000

Changing carriage rate of Neisseria meningitidis among university students during the first week of term: cross sectional study.

OBJECTIVE: To determine the rates of, and risk factors for, meningococcal carriage and acquisition among university students. DESIGN: Repeated cross sectional study. PARTICIPANTS: 2,507 students in their first year at university. MAIN OUTCOME MEASURES: Prevalence of carriage of meningococci and risk factors for carriage and acquisition of meningococci. RESULTS: Carriage rates for meningoccoci increased rapidly in the first week of term from 6.9% on day 1, to 11.2% on day 2, to 19.0% on day 3, and to 23.1% on day 4. The average carriage rate during the first week of term in October among students living in catered halls was 13.9%. By November this had risen to 31.0% and in December it had reached 34. 2%. Independent associations for acquisition of meningococci in the autumn term were frequency of visits to a hall bar (5-7 visits: odds ratio 2.7, 95% confidence interval 1.5 to 4.8), active smoking (1.6, 1.0 to 2.6), being male (1.6, 1.2 to 2.2), visits to night clubs (1. 3, 1.0 to 1.6), and intimate kissing (1.4, 1.0 to 1.8). Lower rates of acquisition were found in female only halls (0.5, 0.3 to 0.9). The most commonly acquired meningococcal strain was C2a P1.5 (P1.2), which has been implicated in clusters of invasive meningococcal disease at other UK universities. CONCLUSIONS: Carriage rates of meningococci among university students increase rapidly in the first week of term, with further increases during the term. The rapid rate of acquisition may explain the increased risk of invasive meningococcal disease and the timing of cases and outbreaks in university students.

Activities of Daily Living↗
PubMed2000

Risk factors for hepatitis C virus infection in United States blood donors. NHLBI Retrovirus Epidemiology Donor Study (REDS)

Injection drug use (IDU) is a known risk factor for hepatitis C virus (HCV) infection, but the strength of other parenteral and sexual risk factors is unclear. In 1997, we performed a case-control study of 2,316 HCV-seropositive blood donors and 2,316 seronegative donors matched on age, sex, race/ethnicity, blood center, and first-time versus repeat-donor status. Odds ratios (OR) and 95% confidence intervals (CIs) were calculated using conditional logistic regression. Questionnaires were returned by 758 (33%) HCV(+) and 1,039 (45%) control subjects (P =.001). The final multivariate model included only the following independent HCV risk factors: IDU (OR = 49.6; 95% CI: 20.3-121.1), blood transfusion in non-IDU (OR = 10.9; 95% CI: 6.5-18.2), sex with an IDU (OR = 6.3; 95% CI: 3.3-12.0), having been in jail more than 3 days (OR = 2.9; 95% CI: 1.3-6.6), religious scarification (OR = 2.8; 95% CI: 1.2-7. 0), having been stuck or cut with a bloody object (OR = 2.1; 95% CI: 1.1-4.1), pierced ears or body parts (OR = 2.0; 95% CI: 1.1-3.7), and immunoglobulin injection (OR = 1.6; 95% CI: 1.0-2.6). Although drug inhalation and a high number of lifetime sex partners were significantly more common among HCV seropositives, they were not associated with HCV after controlling for IDU and other risk factors. IDU, blood transfusion among non-IDU, and sex with an IDU are strong risk factors for HCV among United States blood donors. Weaker associations with incarceration, religious scarification, being stuck or cut with a bloody object, pierced ears or body parts, and immunoglobulin injection must be interpreted with caution.

Adult↗
PubMed2000

Fluorescent amplified-fragment length polymorphism genotyping of Neisseria meningitidis identifies clones associated with invasive disease.

Fluorescent amplified-fragment length polymorphism (FAFLP), a genotyping technique with phylogenetic significance, was applied to 123 isolates of Neisseria meningitidis. Nine of these were from an outbreak in a British university; 9 were from a recent outbreak in Pontypridd, Glamorgan; 15 were from sporadic cases of meningococcal disease; 26 were from the National Collection of Type Cultures; 58 were carrier isolates from Ironville, Derbyshire; 1 was a disease isolate from Ironville; and five were representatives of invasive clones of N. meningitidis. FAFLP analysis results were compared with previously published multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) results. FAFLP was able to identify hypervirulent, hyperendemic lineages (invasive clones) of N. meningitidis as well as did MLST. PFGE did not discriminate between two strains from the outbreak that were classified as similar but distinct by FAFLP. The results suggest that high resolution of N. meningitidis for outbreak and other epidemiological analyses is more cost efficient by FAFLP than by sequencing procedures.

Bacterial Typing Techniques↗
PubMed2000

Dynamics of meningococcal long-term carriage among university students and their implications for mass vaccination.

In the 1997-98 academic year, we conducted a longitudinal study of meningococcal carriage and acquisition among first-year students at Nottingham University, Nottingham, United Kingdom. We examined the dynamics of long-term meningococcal carriage with detailed characterization of the isolates. Pharyngeal swabs were obtained from 2,453 first-year students at the start of the academic year (October), later on during the autumn term, and again in March. Swabs were immediately cultured on selective media, and meningococci were identified and serologically characterized. Nongroupable strains were genetically grouped using a PCR-based assay. Pulsed-field gel electrophoresis was used to determine the link between sequential isolates. Of the carriers initially identified in October, 44.1% (98 of 222) were still positive later on in the autumn (November or December); 57.1% of these remained persistent carriers at 6 months. Of the index carriers who lost carriage during the autumn, 16% were recolonized at 6 months. Of 344 index noncarriers followed up, 22.1% acquired carriage during the autumn term and another 13.7% acquired carriage by March. Overall, 43.9% (397 of 904) of the isolates were noncapsulated (serologically nongroupable); by PCR-based genogrouping, a quarter of these belonged to the capsular groups B and C. The ratio of capsulated to noncapsulated forms for group B and C strains was 2.9 and 0.95, respectively. Sequential isolates of persistent carriers revealed that individuals may carry the same or entirely different organisms at different times. We identified three strains that clearly switched their capsular expression on and off at different times in vivo. One student developed invasive meningococcal disease after carrying the same organism for over 7 weeks. The study revealed a high rate of turnover of meningococcal carriage among students. Noncapsulated organisms are capable of switching their capsular expression on and off (both ways) in the nasopharynx, and group C strains are more likely to be noncapsulated than group B strains. Carriage of a particular meningococcal strain does not necessarily protect against colonization or invasion by a homologous or heterologous strain.

Carrier State↗
PubMed2000

Increased rectal mucosal enteroendocrine cells, T lymphocytes, and increased gut permeability following acute Campylobacter enteritis and in post-dysenteric irritable bowel syndrome.

BACKGROUND AND AIMS: Post-dysenteric irritable bowel syndrome (PD-IBS) develops in up to 25% of patients following Campylobacter enteritis. Our aim was to define the pathological basis of this subgroup of IBS. METHODS: Twenty one patients (group 1) underwent serial rectal biopsy and gut permeability testing following acute Campylobacter enteritis as did 10 PD-IBS patients (group 2) and 12 asymptomatic controls. RESULTS: In group 1, enteroendocrine cell (EC) numbers were markedly increased initially and at six and 12 weeks (p<0.001) compared with controls. Gut permeability, as assessed by the lactulose/mannitol ratio, was significantly elevated, initially and at 12 weeks (p<0.005). CD3, CD4, and CD8 lymphocyte counts in the lamina propria and intraepithelial lymphocytes (IEL) were significantly increased initially compared with controls. At visit 1, EC numbers were positively correlated with CD3 counts (r=0.6, p=0.01). At one year, seven subjects (five with persistent loose stools) had rectal biopsies which showed significantly elevated EC, CD3, and IEL counts. In group 2, EC and IEL counts were significantly increased compared with controls (p<0.001), as was gut permeability (p<0.01). CONCLUSION: Increased EC, T lymphocytes, and gut permeability are acute changes following Campylobacter enteritis which can persist for more than a year and may contribute to PD-IBS.

Acute Disease↗
PubMed1999

Invasive meningococcal disease among university undergraduates: association with universities providing relatively large amounts of catered hall accommodation.

The incidence of invasive meningococcal disease (IMD) among UK university students and non-students of similar age was investigated. In addition, we sought to identify structural risk factors associated with high rates of IMD in individual universities. Cases were ascertained via Consultants in Communicable Disease Control (or equivalent officers) between September 1994 and March 1997. Data on individual universities were obtained from university accommodation officers. University students had an increased annual rate of invasive meningococcal disease (13.2/10(5), 95% CI 11.2-15.2) compared with non-students of similar age in the same health districts (5.5/10(5), CI 4.7-6.4) and in those health districts without universities (3.7/10(5), CI 2.9-4.4). This trend was highly significant. Regression analysis demonstrated catered hall accommodation to be the main structural risk factor. Higher rates of disease were observed at universities providing catered hall places for > 10% of their student population (15.3/10(5), CI 11.8-18;8) compared with those providing places for < 10% of students (5.9/10(5), CI 4.1-7.7). The majority of IMD amongst students was caused by serogroup B organisms. University students in the UK are at increased risk of IMD compared with non-students of a similar age. The incidence of IMD tends to be greatest at universities with a high provision of catered hall accommodation.

Adolescent↗
PubMed1999

Seven-week interval between acquisition of a meningococcus and the onset of invasive disease. A case report.

Invasive meningococcal disease (IMD) is thought to occur within a few days of pharyngeal acquisition of Neisseria meningitidis. During a longitudinal study of carriage and acquisition among 2453 first-year undergraduates we identified a male student from whom N. lactamica was isolated in October 1997 followed by N. meningitidis in December 1997. In mid-January 1998 this student suffered a mild episode of IMD (meningitis) during which N. meningitidis was isolated from his CSF. The meningococcus carried in December 1997 was phenotypically and genotypically indistinguishable from the invading organism, suggesting the possibility that the organism may have been carried for 7 weeks prior to the onset of invasive disease. Further studies are needed to assess more accurately the range of asymptomatic carriage prior to disease onset.

Adult↗
PubMed1999

TT virus infection in patients with hepatitis C: frequency, persistence, and sequence heterogeneity.

TT virus (TTV) was recently identified in the serum of a patient with hepatitis. The role of TTV in liver disease has not been established. Three polymerase chain reaction (PCR) protocols were used to detect TTV DNA in sera of persons infected with hepatitis C virus (HCV) and in blood donors. Sera from 11.5% of HCV-infected patients and 7.7% of blood donors were positive by protocols 1 or 2. In contrast, 48.7% and 57.7% of sera, respectively, were positive when tested by protocol 3. There was no difference in the severity of hepatitis in persons coinfected with TTV and HCV when compared with those infected with HCV alone, regardless of which TTV PCR protocol was used. TTV DNA persisted in serum samples taken up to 6 years apart in individual patients. Sequence analysis indicated that most viral sequences were distinct between patients, and there was evidence of genetic heterogeneity and viral evolution within individuals.

Adolescent↗
PubMed1999

Clinical effectiveness, policies, and practices for influenza and pneumococcal vaccines.

Pneumococcal disease and influenza impact public health considerably. S pneumoniae probably accounts for almost 14,000 deaths and more than 23,000 admissions to National Health Service hospitals per annum. Influenza epidemics occur frequently and unpredictably with the potential to inflict morbidity and mortality on a massive scale. Both diseases pose maximum risks to persons with underlying chronic illnesses. Assessing the effectiveness of pneumococcal and influenza vaccines presents complex methodological problems. However, despite these difficulties, a body of evidence has accumulated suggesting that pneumococcal vaccines offer substantial protection against both bacteremia and pneumonia among healthy low-risk adults, but only against bacteremia in those considered high-risk. There is now strong evidence that the influenza vaccine protects high-risk patients from both hospitalization and death. Although most European countries now have national guidelines for vaccination of high-risk patients, both vaccines remain underused in modern clinical practice mainly due to poor organization.

Adult↗
PubMed1998

Sustained reduction in the carriage of Neisseria meningitidis as a result of a community meningococcal disease control programme.

The effect of a community intervention programme of antibiotics and meningitis vaccine on pharyngeal carriage of Neisseria meningitidis was investigated. Carriage rates were determined in pupils at both secondary schools (ages 11-18 years) included in the community intervention programme and compared with two schools outside the area matched for socio-economic status. A total of 1869 pupils were studied 6 months after the programmes, and 2457 pupils after 11 months. Six months after the programme was completed there was a 72% reduction in pharyngeal carriage of Neisseria meningitidis in pupils attending the schools in the intervention area compared with pupils in the control schools. After 11 months this difference persisted in the 11-14 age group but not in the 15-18 age group. No resistance to the antibiotics used in the programme was found. A community intervention programme of antibiotics and vaccine for the control of meningococcal disease led to a long-term reduction in Neisseria meningitidis carriage in some age groups.

Adolescent↗
PubMed1998

Association between MHC class II alleles and clearance of circulating hepatitis C virus. Members of the Trent Hepatitis C Virus Study Group.

The frequencies of HLA class I antigens and class II haplotypes were compared in subjects with previous (polymerase chain reaction [PCR]-negative) or with persistent (PCR-positive) hepatitis C virus (HCV) infection and in HCV patients with mild versus severe histologic activity scores on liver biopsy. The DRB1*11 allele group was found in 11 (31.4%) of 35 subjects with previous infection and in 11 (8.2%) of 135 subjects with persistent infection (P < .001). The DQB1*0301 allele was found in 18 (51.4%) of 35 subjects with previous infection and in 33 (24.4%) of 135 patients with persistent infection (P < .002). Both observations remained significant after correction for multiple testing. No significant association was shown between severity of disease and any HLA class I or II type. Thus, the HLA class II alleles DRB1*11 and DQB1*0301 are associated with clearance of circulating HCV.

Adult↗
PubMed1998

Appendicectomy, childhood hygiene, Helicobacter pylori status, and risk of inflammatory bowel disease: a case control study.

AIMS: To examine the relation between inflammatory bowel disease and appendicectomy, childhood domestic hygiene, and Helicobacter pylori infection. METHODS: Case control study involving 213 patients with ulcerative colitis, 110 with Crohn's disease, and 337 controls having elective surgery. RESULTS: Nine patients with ulcerative colitis (4.5%) reported a previous appendicectomy compared with 57 controls (19%) (odds ratio (OR) 0.20, 95% confidence interval (CI) 0. 1-0.4, p<0.0001). The inverse association was unaffected by excluding operations performed after the age of onset of ulcerative colitis and was stronger for appendicectomy performed before age 20 (OR 0.14). No association with appendicectomy was found for Crohn's disease and no associations with tonsillectomy for either disease. The availability of a fixed hot water supply in early childhood (before age 11) was associated with Crohn's disease (OR for hot water not always versus always available 0.56, 95% CI 0.3-0.9, p=0. 02) but not with ulcerative colitis. No other aspect of domestic hygiene before or after age 11 was associated with either Crohn's disease or ulcerative colitis. Although H pylori seroprevalence was positively associated with overcrowding (p<0.001) and the absence of running hot water in childhood it was not associated with the presence of either Crohn's disease or ulcerative colitis. H pylori seroprevalence was no lower in patients who had been exposed to sulphasalazine than in controls or those not exposed. CONCLUSIONS: Our findings confirm the strong inverse association between previous appendicectomy and the development of ulcerative colitis and suggest that the protective effect is greater for appendicectomy performed in childhood.

Adolescent↗
PubMed1998

Protracted outbreak of Salmonella typhimurium definitive phage type 170 food poisoning related to tripe, 'pig bag', and chitterlings.

An outbreak of food poisoning around South Yorkshire due to Salmonella typhimurium definitive phage type 170 related to eating tripe, 'pig bag', and chitterlings was associated with a common supplier. Possible links with other suppliers were considered. Twenty-two cases occurred between 11 April 1995 and 7 May 1995. The situation was complicated by the complex distribution network of suppliers and by possible cross contamination in the retail outlets. This complexity created difficulties in the collection, recording and subsequent analysis of the data. The investigation of the outbreak and the subsequent control measures are discussed. Some of the difficulties of monitoring foodborne intestinal disease are highlighted.

Adolescent↗
PubMed1997

Prevalence of gastrointestinal symptoms six months after bacterial gastroenteritis and risk factors for development of the irritable bowel syndrome: postal survey of patients.

OBJECTIVE: To measure the prevalence of gastrointestinal symptoms six months after bacterial gastroenteritis and determine risk factors and associations with postdysenteric symptoms. DESIGN: Postal questionnaire. SETTING: Nottingham Health Authority. SUBJECTS: 544 people with microbiologically confirmed bacterial gastroenteritis between July 1994 and December 1994. MAIN OUTCOME MEASURES: Prevalence of gastrointestinal symptoms and relative risks for development of the irritable bowel syndrome and self reported altered bowel habit. RESULTS: A quarter of subjects reported persistence of altered bowel habit six months after an episode of infective gastroenteritis. Increasing duration of diarrhoea, younger age, and female sex increased this risk, whereas vomiting as part of the illness reduced the risk. One in 14 developed the irritable bowel syndrome with an increased risk seen in women (relative risk 3.4: 95% confidence interval 1.2 to 9.8) and with duration of diarrhoea (6.5; 1.3 to 34 for 15-21 days). CONCLUSIONS: Persistence of bowel symptoms commonly occurs after bacterial gastroenteritis and is responsible for considerable morbidity and health care costs.

Activities of Daily Living↗
PubMed1997

Diabetes mellitus, anti-secretory drugs and other risk factors for campylobacter gastro-enteritis in adults: a case-control study.

The epidemiology of notified cases of campylobacter gastroenteritis in adults in Nottingham Health District was investigated using a case-control study with a postal questionnaire to ascertain data on risk factors. Over a 14-month period 531 cases (a 73% response rate of all laboratory confirmed cases) and 512 controls replied. Conditional logistic regression analysis was used to determine independent associations with infection. These included foreign travel (odds ratio (OR) 3.4; 95% confidence intervals (CI) 2.0-5.7), diabetes mellitus (OR 4.1, CI 1.1-17), medication with omeprazole (OR 3.5, CI 1.1-12) and H2 and H2 antagonists (OR 3.7, CI 1.3-15), contact with puppies (OR 11.3, CI 1.2-105), eating chicken (OR 1.4, CI 1.1-1.8) and drinking milk from bottles with tops damaged by a bird (OR 3.3, CI 1.0-11). Preparing main meals (OR 0.9, CI 0.8-1.0) and drinking delivered milk (OR 0.6, CI 0.4-0.9) were associated with a reduced risk of campylobacter infection. Foreign travel was reported in 25% of cases and another 15% had significant associations with other risk factors. The majority of cases, 60%, remained unexplained, indicating the need for further evolution of sporadic cases.

Adolescent↗
PubMed1996

Serum HCV RNA levels assessed by quantitative NASBA: stability of viral load over time, and lack of correlation with liver disease. The Trent HCV Study Group.

BACKGROUND/AIMS: We used the hepatitis C virus quantitative NASBA technique to evaluate the stability of viral load within individuals with chronic hepatitis C, to determine the range of viraemic load between individuals, and to assess the usefulness of hepatitis C virus RNA quantitation in predicting the severity of underlying hepatitis C virus-induced liver disease. METHODS: Hepatitis C virus RNA was determined, using the quantitative NASBA assay, in multiple serum samples from 11 individuals with chronic hepatitis C over an average time period of 11 months (range = 3-23 months), and in single serum samples from a further 10 individuals. RESULTS: In 10/11 individuals the hepatitis C virus RNA titres were within one log10 copies/ml of each other during this time period. In the eleventh, there was a rise of 1.36 log10 copies/ml in two serum samples taken 8 months apart. The viraemic load varied by 2.79 log10 copies/ml serum between individuals. There were no correlations between mean RNA levels and total biopsy scores (either Knodell or Sheffield scores), or the individual components of the biopsy scoring systems, except the sinusoidal infiltration component of the Sheffield score. There was also no difference in viral RNA levels between those infected with type 1 as compared to type 3 virus, with a mean level in both groups of 7.2 log10 copies/ml. CONCLUSIONS: Hepatitis C virus serum RNA level is stable within individuals within the studied time period. Viral load varies between infected individuals but is not a useful prognostic indicator of the severity of virus-induced liver disease.

Adult↗