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N S Crowcroft

Publications and source records attributed to N S Crowcroft.

At least 19 recordsLinked to original sources
PubMed2003

How best to estimate the global burden of pertussis?

In most countries, pertussis surveillance is inadequate for accurately estimating numbers of cases or deaths. Good estimates are needed to help set priorities for vaccination programmes. We aimed to develop a simple, reliable, and explicit method for estimating pertussis cases and deaths for children under 15 years to calculate the global disease burden in 1999. We estimated the proportion of susceptible children becoming infected in countries with poor vaccination coverage (<70%) in 1999 at 30% by 1 year, 80% by 5 years, and 100% by 15 years of age and for countries with good coverage (> or =70%) at 10% by 1 year, 60% by 5 years, and 100% by 15 years. Vaccine efficacy was estimated at 80% for preventing infection and 95% for preventing deaths. We used UN population estimates and vaccination coverage reported to WHO (adjusted for specific survey data if available). Case fatality ratios for countries with high and low child mortality were derived from published and unpublished work. For some countries with good vital events registration we used reported deaths adjusted for underascertainment. In 1999 there were an estimated 48.5 million pertussis cases in children worldwide. Deaths from pertussis were estimated at 390000 and at 295000 after adjustment for local data sources. Based on this approach, disability-adjusted life years from pertussis (12.7 million) in 2000 exceeded those of other preventable diseases such as lung cancer (11.4 million) and meningitis (5.8 million). This simple approach yields estimates that can be used for setting vaccination programme priorities. Better data are needed on the public health importance of pertussis in high mortality countries, the benefits of incomplete vaccination, and the harm from delayed vaccination.

Adolescent↗
PubMed2003

Tetanus in England and Wales, 1984-2000.

A review of national tetanus surveillance in England and Wales during 1984-2000 was undertaken to evaluate the surveillance system and national vaccination policy. Hospital Episode Statistics for tetanus in England for fiscal years 1989/90-1995/6 were also examined to estimate under-reporting. A total of 175 cases of tetanus were reported, giving an annual incidence of 0.20 per million, the lowest levels ever recorded. The highest incidence was in those aged over 64 years (0.66 per million) with no significant sex difference. Twenty (11%) cases were reported in people who were eligible for routine childhood vaccination. Outdoor injuries were the commonest reported exposure risk. Tetanus case under-reporting was estimated as 54-64%. We conclude that GPs should ensure that all their patients are fully vaccinated, targeting those born before 1961. High childhood tetanus vaccination coverage remains a priority. As the disease becomes rarer, enhanced tetanus case surveillance is essential for tetanus immunization policy evaluation.

Adolescent↗
PubMed2003

Severe and unrecognised: pertussis in UK infants.

AIMS: To diagnose pertussis using culture, polymerase chain reaction, and serology, in children admitted to intensive care units (PICUs) and some paediatric wards in London, and in their household contacts to determine the source of infection. METHODS: Infants <5 months old admitted to London PICUs between 1998 and 2000 with respiratory failure, apnoea and/or bradycardia, or acute life threatening episodes (ALTE), and children <15 years admitted to paediatric wards at St Mary's and St George's Hospitals between 1999 and 2000 with lower respiratory tract infection, apnoea, or ALTE were studied. RESULTS: Sixty seven per cent of eligible children (142/212) were recruited; 23% (33/142) had pertussis, 19.8% (25/126) on the PICU and 50% (8/16) on wards. Two died. Only 4% (6/142) were culture positive. Pertussis was clinically suspected on admission in 28% of infants (7/25) on the PICU and 75% (6/8) on the wards. Infants on PICU with pertussis coughed for longer, had apnoeas and whooped more often, and a higher lymphocyte count than infants without pertussis. Pertussis and respiratory syncytial virus (RSV) co-infection was frequent (11/33, 33%). Pertussis was confirmed in 22/33 (67%) of those who were first to become ill in the family. For 14/33 children the source of infection was a parent; for 9/33 the source of pertussis was an older fully vaccinated child in the household. CONCLUSIONS: Severe pertussis is under diagnosed. An RSV diagnosis does not exclude pertussis. Future changes to the UK vaccination programme should aim to reduce pertussis transmission to young infants by their parents and older siblings.

Anti-Bacterial Agents↗
PubMed2003

Hepatitis A virus infection control: an audit of practice in England and Wales prior to guidelines being published.

This survey was conducted in September 2001 to audit the practice of Consultants in Communicable Disease Control (CsCDC) and to gain a systematic picture of pre-guideline approaches to the control of hepatitis A virus infection in England and Wales. An audit form was distributed to all CsCDC by email and responses were entered in a database and analysed. Response rate is estimated at 44%. CsCDC predominantly recommend vaccination for prevention. For 31% of the CsCDC, index cases were not reported within a week of the onset of illness. As a result, vaccine was often used sub-optimally. By contrast 95% of the CsCDC were informed of an index case within two weeks of onset of illness, in time for effective use of human normal immunoglobulin (HNIG). CsCDC were cautious in the use of HNIG for a number of reasons including concerns about variant Creutzfeldt-Jacob Disease (vCJD). A substantial proportion (between 5% and 28% for different age groups) of CsCDC did not recommend any active prevention among close family contacts of a case. Important ways to improve practice include facilitating use of HNIG and speeding up reporting by doctors and laboratories.

Communicable Disease Control↗
PubMed2002

Contribution of RSV to bronchiolitis and pneumonia-associated hospitalizations in English children, April 1995-March 1998.

Estimates of the number of hospitalizations attributable to specific pathogens are required to predict the potential impact of vaccination. All hospital admissions for lower respiratory tract infection (LRI) in children < 5 years in England in 1995-8 were reviewed. Most admissions (76.8%) were not associated with specific organisms. Seasonality in pathogens that cause bronchiolitis and pneumonia was used to predict the proportion of cases with unspecified aetiology attributable to different organisms using multiple linear regression. Of 12,298 admissions for LRI, 17.5% were due to RSV infection. An estimated 74.8% (95% CI, 72.0-77.7%) of 'unspecified bronchiolitis' admissions and 16.3% (95% CI, 13.7-18.8%) of unspecified pneumonia' admissions were RSV related. The total mean annual incidence of hospital admissions attributable to RSV is 28.3/1000 children < 1 year of age, and 1.3/1000 children 1-4 years old. The greater burden of RSV infection than indicated through discharge data is revealed through applying simple statistical methods.

Bronchiolitis↗
PubMed2002

National enhanced surveillance of meningococcal disease in England, Wales and Northern Ireland, January 1999-June 2001.

Enhanced surveillance of meningococcal disease (ESMD) was implemented nationally across ten regions of England, Wales and Northern Ireland from 1 January 1999. It aims to deliver more sensitive surveillance than laboratory reporting by including clinically diagnosed but laboratory unconfirmed cases. Consultants in Communicable Disease Control (CsCDC) report all clinically diagnosed cases of meningococcal disease (MD) to the Regional Epidemiologist in the relevant regional unit of the Public Health Laboratory Service (PHLS) Communicable Disease Surveillance Centre (CDSC). These reports are reconciled with laboratory data from the PHLS Meningococcal Reference Unit and then forwarded to the national CDSC where further reconciliation with laboratory data takes place. In addition, CsCDC are asked to report any clusters of MD that occur. Between 1 January 1999 and 30 June 2001, 12,074 cases of MD were ascertained through ESMD. The majority (57%) were laboratory confirmed. The estimated incidence of MD fell between 1999 and 2001 from 9.2 to 8.0 per 100,000 population. Of laboratory confirmed cases, the number of cases of serogroups B and W135 increased and of serogroup C and of ungrouped meningococcal infection decreased. Variation between regions was considerable and deserves further investigation. Of 11,522 cases with a reported clinical diagnosis, 53.6% were diagnosed as septicaemia, 32.6% as meningitis, 12.5% as both septicaemia and meningitis, and 13% had other invasive MD. Between 1 January 1999 and 30 June 2001 698 deaths were reported, an overall case fatality rate (CFR) of 5.8%; 567 deaths were in confirmed cases and 131 probable (CFR 8.2% and 2.5%, respectively). CFR was higher in serogroup C (13.5%) than B (5.8%). No peak in serogroup C meningococcal infection occurred in the winter of 2000/1 and no clusters of serogroup C meningococcal infection were reported in the first half of 2001. ESMD provides information about the epidemiology of MD that is more complete than statutory notification and laboratory surveillance and is useful for evaluating the impact of the meningococcal serogroup C vaccination programme and of the other non-vaccine preventable serogroups.

Adolescent↗
PubMed2002

UK guidelines for use of erythromycin chemoprophylaxis in persons exposed to pertussis.

Pertussis is well controlled in the UK as a result of an effective vaccination programme. Nevertheless, the disease has not been eliminated, and cases still occur in the most vulnerable group of young infants. Erythromycin chemoprophylaxis has been advocated for use in contacts to prevent secondary cases but the evidence for its use is weak. These guidelines are based on a review of the evidence and aim to help clinicians make more rational decisions on the use of erythromycin chemoprophylaxis for pertussis. Erythromycin has well-established side effects and so its use should be limited to situations where it is likely to be of greatest benefit. If a clinically suspected or confirmed case of pertussis is identified who is also in household contact with someone at greatest risk from pertussis--young infants, especially neonates--then erythromycin chemoprophylaxis should be considered. The aim is to protect those at greatest risk from pertussis by offering chemoprophylaxis to them, to all their household contacts who are unimmunized and to contacts who are 5 years or older if they did not receive a pre-school pertussis booster (not given to those born before 1996 in the United Kingdom). There is no evidence of any benefit from chemoprophylaxis given more than 21 days from the date of onset of the primary case. Unimmunized or partially immunized cases and contacts should complete their course of vaccine.

Antibiotic Prophylaxis↗
PubMed2002

Deaths from pertussis are underestimated in England.

AIMS: To improve estimates of deaths from pertussis in England and to identify reasons for under ascertainment. METHODS: Comparison of deaths identified from enhanced laboratory pertussis surveillance, hospital episode statistics (HES), and Office for National Statistics (ONS) death registrations in England, 1994 to 1999. RESULTS: A total of 33 deaths were identified, 88% of infants less than 4 months old. There was overlap between all sources; 22 deaths were identified in the enhanced pertussis surveillance system, 18 in ONS mortality data, and nine in HES. Children who had died from pertussis without mention of pertussis on the death certificate were more likely to have been certified by coroners than those with mention of pertussis (p = 0.0005). Using capture-recapture analysis, the total number of deaths from pertussis in the five and a half year period is estimated to be 46 (95% CI 37 to 71), or around nine deaths per year. CONCLUSIONS: National mortality statistics significantly under estimate deaths from pertussis in England and are inadequate for monitoring the national immunisation programme. The largest number of deaths is identified through enhanced laboratory surveillance. Death registration systems should take into account available microbiological information to ensure that cause of death is accurately assigned.

Cause of Death↗
PubMed2002

Viral haemorrhagic fevers in Europe--effective control requires a co-ordinated response.

Viral haemorrhagic fevers (VHF) have attracted the attention of the medical world and general public for many reasons, some based in reality and more on misinformation. They are amongst the highest profile infections in the public mind, because they are thought to be highly infectious and to kill most of their victims in a dramatic way (1,2). To add to the intrigue, mysteries remain about the source of some of the viruses involved. They emerge and re-emerge in many countries, most recently Ebola in Uganda in 2000 (3) and Gabon in 2001/02 (4), and Congo Crimean Haemorrhagic Fever (CCHF) in Kosovo (5) and Pakistan in 2001 (6). Large outbreaks have affected populations in endemic areas, living mainly in inaccessible areas or refugee camps where living conditions are very difficult. Poorly resourced medical facilities have played a role in amplifying transmission and infection control measures have been difficult or virtually impossible to establish. These viruses are likely to remain a threat until the reservoir is identified and as long as endemic areas are afflicted with ecological change, poverty and social instability. Recent events since September 11 2001 remind us of their potential to be used as weapons, and that fear can present a risk to public health.

Communicable Disease Control↗
PubMed2002

Guidelines on the management of, and exposure to, rash illness in pregnancy (including consideration of relevant antibody screening programmes in pregnancy).

These guidelines, produced by the Public Health Laboratory Service (PHLS) aim to help decision making in the investigation and management of pregnant women who have 'a rash compatible with a systemic viral illness', or who have contact with a person with such an illness. They address particularly rubella, parvovirus B19, and varicella-zoster virus infection, but consider other infective causes of rash illness in the United Kingdom. The guidelines give the magnitude and degrees of risk to the fetus in terms of outcomes for the gestation at which maternal infection occurs. Recent changes in epidemiology and management lead to the following specific advice, which both updates and re-affirms established guidelines. All pregnant women with a non-vesicular rash illness should be investigated simultaneously for rubella and parvovirus B19 infection. All pregnant women who have had significant contact with a person suffering from a non-vesicular illness should be investigated for asymptomatic parvovirus B19 infection, and for asymptomatic rubella infection unless there is satisfactory evidence of past rubella infection (vaccine or natural infection). A significant contact is defined as being in the same room for over 15 minutes, or face-to-face contact. Specific investigation to detect asymptomatic rubella reinfection is not advised. It is essential to confirm by adequate laboratory investigation all cases of possible rubella and parvovirus B19 infection in pregnancy. Management of proven rubella in pregnancy should be based on established risks of adverse outcome. Women with proven parvovirus B19 infection in the first 20 weeks of pregnancy should be followed by regular, ultrasound scanning, and referred to Regional Units of Fetal Medicine if hydrops fetalis is detected. Parvovirus B19 antibody screening in pregnancy is not advised, and consensus has been reached on the procedures to be followed for rubella antibody screening, including the concentration of antibody that reflects past infection. Oral antiviral treatment (aciclovir) is advised with informed consent for pregnant women who present within 24 hours of onset of varicella. Referral to hospital and intravenous antiviral treatment is indicated for pregnant women with complications and/or risk factors, or whose illness continues for six days or more. Pregnant women exposed to varicella or herpes zoster can be reassured as to their protection if they themselves have a history of varicella or herpes zoster. If this history is uncertain or not known, susceptibility should be tested, and varicellazoster immunoglobulin (VZIG) offered to those found susceptible if within 10 days of first exposure. Infants whose mothers develop varicella 7 days before to 7 days after delivery should be given VZIG, and aciclovir if onset was 4 days before to 2 days after delivery.

Communicable Disease Control↗
PubMed2002

West Nile virus and the threat to the UK.

West Nile virus (WNV) is an RNA virus and a member of the Flaviviridae family. The recent geographical expansion of WNV into areas where no activity had been previously reported has been highlighted by the detection of WNV in North America. There is also a recent trend for more numerous and serious outbreaks in Eurasia. The main hosts are birds and the principle vectors are mosquitoes, usually of the genus Culex. Although most infected people do not become symptomatic, severe diseases such as encephalitis and, less commonly, aseptic meningitis may occur, more frequently in the elderly. The public can be protected by giving advice on the avoidance of mosquito bites and by the implementation of ecological surveillance and measures to reduce the mosquito population. While a few human cases have been identified in returning travellers, WNV has not been reported in any animal or bird in the UK. However, this may simply indicate that the diagnosis has not been sought. Potential avian hosts and mosquito vectors of WNV are present in the UK and birds migrate to the UK from areas of endemic WNV activity. However, the population density of mosquitoes is relatively low and therefore the risk of WNV being transmitted in the UK is thought to be low. We lack sufficient information on the ecology of the virus, and on mosquito populations, to accurately determine this risk. Clinicians are advised to consider WNV as a differential diagnosis, especially in patients over 50 years old with a clinical picture of viral encephalitis or aseptic meningitis presenting in the summer months.

Animals↗
PubMed2002

Enhanced surveillance scheme for suspected meningococcal disease in five regional health authorities in England: 1998.

Enhanced surveillance of meningococcal disease (ESMD) began in five English regions on 1st January 1998. The aims of the scheme were to obtain accurate incidence data and develop a robust surveillance system with which to monitor the impact of a new meningococcal serogroup C conjugate vaccine. During 1998, 2,314 suspected cases of meningococcal disease were identified. The majority (84%) was classified as invasive meningococcal disease, with infection of N. meningitidis confirmed in 66%. Sixteen per cent of suspected cases were subsequently given an alternative diagnosis. Age differences between those classified as meningococcal disease and those not, implied a higher index of suspicion of meningococcal disease in younger children. Regions with high rates of meningococcal disease were due to a higher rate of serogroup C. ESMD increased ascertainment of meningococcal disease and deaths. Cases were 34% greater than identified through statutory notifications, an additional 6.8% confirmed infections were identified than were reported to the PHLS Meningococcal Reference Unit (MRU) and deaths were 24% greater than death registrations. These data were used to inform the national meningococcal serogroup C conjugate vaccination programme in England and Wales. In 1999 ESMD was extended to all regions of England, Wales and Northern Ireland.

Adolescent↗
PubMed2002

Estimating the burden of serogroup C meningococcal disease in England and Wales.

In 1999 a new conjugate vaccine for serogroup C meningococcal disease was licensed for use in the UK. In order for an appropriate vaccination strategy to be developed the burden of serogroup C disease in England and Wales needed to be established. This was done using data from an enhanced surveillance scheme alongside routine laboratory reports and a total of 5,052 cases of serogroup C disease in England and Wales between 1993 and 1998 were estimated. Among these, an estimated 398 died and 1,767 were admitted to intensive care units (ITUs). The greatest burden of disease was in young children and teenagers. The current literature identified four studies reporting sequelae following serogroup C meningococcal disease. These provided estimates of sequelae in the range of 6.5% and 45% and presented some evidence of higher levels than occur following serogroup B meningococcal disease. This information was provided to the Joint Committee on Vaccination and Immunisation to inform policy to implement a serogroup C conjugate vaccination programme in the UK. The vaccination programme has since been justified by the dramatic reduction in serogroup C meningococcal cases.

Adolescent↗
PubMed2001

Guidelines for the control of hepatitis A virus infection.

The PHLS Advisory Committee on Vaccination and Immunisation, following a review of the evidence on control measures for preventing hepatitis A virus (HAV) infection and widespread consultation, has prepared the following guidelines. They include a description of the current epidemiology of HAV infection in England and Wales, where most individuals are now susceptible to HAV. HAV infection is uncommon, with around 1000 infections notified per year in England and Wales. Clusters occur in families and in settings where potential for faecal/oral spread is high, e.g. day care centres, nurseries, primary schools. Larger outbreaks have been recorded in men who have sex with men and injecting drug users. Personal hygiene remains the cornerstone of measures for preventing HAV infection and its spread. Those with haemophilia, hepatitis B or C virus infection or liver cirrhosis, intravenous drug users and men who have sex with men should be offered HAV vaccination as a preventive measure. HAV vaccine should be used for preventing secondary cases and outbreaks provided that patients are informed that the latest date the vaccine is most likely to be effective in preventing disease in contacts is probably 7 days from onset of illness in the primary case. Human normal immunoglobulin (HNIG) should be offered in addition or in preference to vaccine for contacts who are more than 7 days from onset of illness in the primary case, and for those at risk of adverse outcome of HAV infection. Individuals at particular risk of an adverse outcome to infection include those more than 50 years old, with liver cirrhosis of any cause, or with pre-existing hepatitis B or C virus infection. HAV vaccine should be used to prevent infection for travellers to countries where HAV infection is a risk. HNIG is no longer indicated for travellers. Children travelling to such countries should be offered vaccine from 5 years and consideration should be given to vaccinating those aged 1-4 years.

Adult↗