Carriers of Neisseria meningitidis in household contacts of meningococcal disease cases in Catalonia (Spain)

A population-based study was carried out in Catalonia (Spain) from May 1998 to April 1999 to determine the prevalence of Neisseria meningitidis strains in meningococcal disease (MD) cases and their contacts, as well as the prevalence of meningococci in close contacts of patients with MD, and risk factors for its carriage. A total of 364 close contacts of 87 patients with MD were studied. Throat samples were collected by hospital staff before rifampicin chemoprophylaxis was begun. For each contact, a questionnaire was completed for sociodemographic and epidemiological data. A total of 61 contacts (an overall prevalence of 16.8%) were carriers of meningococcal strains (40 B, 10 C, 1 Z and 10 non-groupable isolates). This prevalence is two to three times higher than in the general population (5-10%). In 33/61 microbiologically confirmed cases (54%) and in 9/26 probable cases (35%), contacts carrying N. meningitidis were found. In 22/33 confirmed cases with carrier contacts, it was possible to study the phenotype of the carrier and patient strains (sero-group, serotype and serosubtype). In 14 cases (64%), both strains were identical, in four cases, only a minor change was observed, in three cases, some strain (from the case or from his contact) was non-serotypable and non-serosubtypable, and in one case, both isolates were completely different. Bivariate analysis identified five statistically significant risk factors for meningococcal carriage: age (5-9 years old), meningococcal A+C vaccination, severe household overcrowding, social class and heavy active smoking (>20 cigarettes a day). Multivariate analysis revealed that of these five variables, only heavy active smoking remained statistically significant when the other factors were controlled.     

An epidemic of meningococcal infection at Zaria, Northern Nigeria. 3. Meningococcal carriage

Meningococcal carriage was studied in household contacts of patients with group A meningococcal disease and in controls. The carriage rate of group A meningococci among 1,098 household contacts was low (3.8%) and only slightly higher than the carriage rate found among 416 controls (2.6%). However, higher carrier rates were found among those in close contact with a patient. Carriage was found most frequently among children and young adults and was commoner in adult females than in adult males. Sulphonamides had no effect on carriage and all 60 strains tested in vitro were resistant to sodium sulphadiazine at a concentration of 10 micrograms/ml.     

Hepatitis B infection in households of acute cases.

Seroepidemiological studies conducted in 369 household contacts of 80 acute cases of hepatitis B in Singapore showed that asymptomatic chronic carriers of hepatitis B surface antigen (HBs Ag) are the main source of acute hepatitis B infection. The HBs Ag prevalence rate in asymptomatic household members was 20% compared with a 6% prevalence for the general population. The majority of the household carriers (60%) were highly infectious with positive hepatitis e antigen (HBe Ag). The overall prevalence of HBV infection (with at least one HBV marker) of the household contacts was 40.7%. Spouses and parents of acute cases had a significantly higher prevalence of HBV infection than other members of the families. HBV prevalence rate showed no association with the household size. Factors associated with the risk of transmission of HBV infection included sharing of various personal and household articles, such as toothbrush, towel, handkerchief, clothing, razor, comb, bed and bedding. Sleeping in the same bedroom, eating together at meals, and sharing of eating and drinking utensils were not associated with an increased risk of transmission of infection. Follow-up studies six months later showed that 30% of the acute cases became chronic HBs Ag carriers (with 46% HBe Ag positive), thus providing an additional source of infection in the families, while 8% of the susceptible household members acquired asymptomatic HBV infection. Health education on the prevention of HBV transmission in the homes of acute cases should be based on sound epidemiological information. Household contacts of acute cases of hepatitis B should be routinely screened and the susceptible vaccinated against the disease as soon as possible.     

Carriage of N. lactamica in a population at high risk of meningococcal disease

Carriage of Neisseria lactamica among household contacts of meningococcal disease (MCD) cases was investigated during an epidemic in Auckland, New Zealand. The overall carriage rate for N. lactamica was 10.5% (95% CI 7.4-13.5%) with a peak carriage rate in 2-year-olds of 61.5% (95% CI 26.6-88.1%). Factors associated with a significant (P < 0.05) increase in the likelihood of carriage included runny nose, the number of people per bedroom and youth. Genetic analysis of isolates revealed a striking correlation of strains within the same household but a high level of diversity between households, suggesting that household contact is an important factor in acquisition. For household contacts aged less than 5 years, there was a higher rate of carriage amongst those in contact with MCD cases under 8 years old than for contacts of cases aged 8 years and over. It is likely that development of MCD is a reflection of the nature and intensity of the exposure to a virulent strain of N. meningitidis, coupled with an absence of host resistance among those individuals not carrying N. lactamica.     

Seroprevalence of SARS coronavirus antibody in household contacts

Between March and July 2003, 671 cases of severe acute respiratory syndrome (SARS) were diagnosed in Taiwan with a total of 84 fatalities. After the epidemic, a serological survey was conducted involving the asymptomatic household contacts. Household contacts of 13 index patients were enrolled in the study. Contact history and clinical symptoms of the household contacts were recorded by standardized questionnaires. Blood samples of patients and household contacts were collected at least 28 days after symptom onset in the index patients or household exposure in the contacts for SARS-associated coronavirus (SARS-CoV) IgG testing. On the basis of this investigation, 29 persons (25 adults and 4 children) were identified as having had unprotected exposure to the index cases before infection-control practices were implemented. Laboratory evaluation of clinical specimens showed no evidence of transmission of SARS-CoV infection to any contacts. This investigation demonstrated that subclinical transmission among household contacts was low in the described setting.     

Transmission of hepatitis B and hepatitis delta viruses in the households of chronic hepatitis B surface antigen carriers: a regression analysis of indicators of risk

To evaluate whether clinical and laboratory features of a hepatitis B surface antigen (HBsAg) carrier can predict risks of infection, its chronicity, and the development of liver disease among close contacts, the authors studied a cohort of 994 first degree relatives or cohabitants (household contacts) of 226 non-drug-addicted chronic HBsAg carriers (index cases), of whom 77% had liver disease and 26% were superinfected by hepatitis D virus (HDV). A logistic form of regression analysis was used to assess the role of each feature in the index case as predictor of hepatitis B virus (HBV)- and HDV-related outcomes among household contacts. Six models of risk, expressed as odds ratios, were assessed by multivariate step-down analysis, with the following results. 1) Infection with HBV in the household contact was independently predicted by the index case being son, sibling, spouse, female, or HBV-DNA positive. 2) Chronic HBsAg carriage in the adult household contact was associated with female sex of the index case and with being a sibling; among young subjects, household contacts were more likely to be chronic HBsAg carriers when the index case was the mother, a sibling, or an HBV-DNA-positive subject. 3) HBV-DNA positivity in the young contact was more likely when the index case was HBV-DNA positive and when she was the mother. 4) HBV-DNA positivity in the absence of hepatitis B e antigen (HBeAg) in serum in the index case was not related to a similar pattern of infection in HBsAg-positive contacts. 5) Super-infection with HDV of an HBsAg-positive household contact was significantly predicted by female sex of the index case and by anti-HDV positivity. 6) Chronic liver disease in a contact was predicted only by HDV superinfection of the index case. We conclude that horizontal, nonparenteral transmission of HBV among siblings plays a major role in the household of HBsAg carriers from an intermediate endemicity area.     

Emergence of fluoroquinolone-resistant Neisseria meningitidis--Minnesota and North Dakota, 2007-2008

Meningoccocal disease causes substantial morbidity and mortality; approximately 10% of cases are fatal. Among those who survive, 10%-15% have long-term sequelae. Nasopharyngeal carriage of Neisseria meningitidis is a precursor to disease; however, the majority of carriers do not develop disease. Household and other close contacts of persons with meningococcal disease have a higher risk for carriage and therefore invasive disease. These persons should receive antibiotic chemoprophylaxis to eliminate nasopharyngeal carriage of N. meningitidis as soon as possible. The rate of secondary disease for close contacts is highest immediately after onset of disease in the index patient; secondary cases rarely occur after 14 days. Ciprofloxacin, a second-generation fluoroquinolone, is an effective single-dose oral chemoprophylaxis agent. Although isolated cases of ciprofloxacin-resistant meningoccocal disease have been described in Argentina, Australia, China, France, India, and Spain, resistance has not been reported in North America. This report describes a cluster of three cases of fluoroquinolone-resistant meningococcal disease that occurred among residents of the border area of North Dakota and Minnesota during January 2007-January 2008. The first of these cases was epidemiologically linked and had closely related molecular features to a 2006 case of fluoroquinolone-susceptible meningococcal disease that occurred in the same geographic region. Until further notice, ciprofloxacin should not be used for chemoprophylaxis of close contacts of persons with meningococcal disease in selected counties in North Dakota and Minnesota. Ceftriaxone, rifampin, and azithromycin are alternative agents.     

The Stonehouse survey: nasopharyngeal carriage of meningococci and Neisseria lactamica.

A total of 6234 nasopharyngeal swabs was collected during a survey of the population of Stonehouse, Gloucestershire in November 1986 as part of an investigation into an outbreak of meningococcal disease. The overall meningococcal carriage rate was 10.9%. The carriage rate rose with age from 2.1% in the 0- to 4-year-olds to a peak of 24.5% in the 15- to 19-year-olds, and thereafter declined steadily with age. Male carriers outnumbered female carriers of meningococci by 3:2. Group B (or non-groupable) type 15 sulphonamide-resistant strains which had caused the outbreak were isolated from 1.4% of subjects. The age distribution of carriers of these strains was similar to that of other meningococci apart from an additional peak in the 5-9-year age group and a more rapid decline in carriage with increasing age. Variations in the carriage rates of the outbreak strain were seen in children attending different schools and in the residents of different areas of the town. The low carriage rate of these strains in a community during a prolonged outbreak supports the hypothesis that these organisms are less transmissible but more virulent than other strains of pathogenic meningococci. Carriage of Neisseria lactamica, which is thought to be important in the development of meningococcal immunity, was most frequent in children under the age of 5 years and was six times commoner in this age group than carriage of Neisseria meningitidis. In older children and adults female carriers of N. lactamica increasingly outnumbered males in contrast to the male preponderance observed with meningococcal carriage.     

Persistence of W135 Neisseria meningitidis carriage in returning Hajj pilgrims: risk for early and late transmission to household contacts

After an outbreak of meningococcal disease caused by Neisseria meningitidis W135, associated with the Hajj pilgrimage in 2001, 15% of returning vaccinated pilgrims carried a single W135 clone, and 55% were still carriers 6 months later. Transmission to 8% of their unvaccinated household contacts occurred within the first few weeks, but no late transmission took place. Public health interventions are needed to protect household contacts.     

Day-care and meningococcal disease in young children.

The Republic of Ireland has the highest incidence of meningococcal disease in Europe with 40% of all cases occurring in children under the age of 5 years. Attending day-care increases the risk of certain infections, including Haemophilus influenzae type b (Hib) meningitis. The risk of meningococcal disease associated with day-care is not known. We conducted a case-control study among pre-school children with 130 laboratory-confirmed cases and 390 controls, matched on age, gender and place of residence, to determine if day-care attendance was a risk factor for meningococcal disease. Multivariate analysis showed that day-care attenders had a lower risk of disease than non-attenders (OR 0.3, 95% CI 0.1-0.7) whereas the number of adults in a household, and household crowding were independent risk factors for disease. Asymptomatic carriers of Neisseria meningitidis are the main source of transmission and these carriers are usually adults. Regular day-care attendance may reduce this risk by removing children from close and prolonged contact with adults.     

Acquisition and carriage of meningococci in marine commando recruits

Meningococcal acquisition is a prerequisite for invasive disease. Three hundred and eleven male marine commando recruits were studied throughout 29 weeks of basic training to identify factors influencing meningococcal carriage and acquisition including troop number, season, smoking, respiratory infection, antibiotic usage and nasopharyngeal bacterial interference flora. A high carriage rate on entry to training (118/311, 37.9%) and subsequent sustained high rates of meningococcal acquisition were found. Of the potential factors examined, only active and passive smoking were found to be associated significantly with meningococcal carriage on entry. The association between active smoking and meningococcal carriage was dose-dependent, with odds ratios (OR) of 2.2 (95% CIs 1.0-4.8) and 7.2 (95% CIs 2.3-22.9) for light and heavy smokers respectively. Passive smoking predisposed independently to carriage (OR 1.8, 95% CIs 1.1-3.0). Active and passive smoking combined to give an attributable risk for meningococcal carriage of 33%. In contrast, despite a high and sustained rate of meningococcal acquisition in the study population, none of the risk factors investigated, including active smoking, was associated significantly with meningococcal acquisition. No cases of meningococcal disease occurred during the 16-month study period. Therefore smoking may increase the duration of meningococcal carriage rather than the rate of acquisition, consistent with the increased risk of meningococcal disease from passive as opposed to active smoking. Public health measures that reduce the prevalence of smoking should reduce the risk of meningococcal disease.     

Detection of intra-familial transmission of shigella infection using conventional serotyping and pulsed-field gel electrophoresis

Pulsed-field gel electrophoresis (PFGE) is commonly used in molecular epidemiology. However, this technique has never been used in studying intra-family spread of enteric diseases in Bangladesh. Our objective was to evaluate the intra-familial transmission of shigella infection using PFGE. Children of either sex, less than 10 years old, who were family contacts of shigella-infected index cases were the study population. PFGE was applied if the same serotypes/sub-serotypes of shigella were isolated from both the index case and the family contact children. In total, 227 index cases were studied. Shigella was isolated from 61 (27%) contact children on day 1 of enrolment, among which Shigella flexneri (41%) and S. boydii (41%) were dominant, followed by S. dysenteriae (10%), S. sonnei (3%), and shigella-like organisms (5%). Seventeen (28%) of the asymptomatic infections in contact children were caused by the same serotype of shigella as that found in the index case. The intra-familial shigella transmission rate was 8% (17/227). Of the 227 contact children, eight (4%) developed diarrhoea during a 10-day follow-up and shigella was isolated from five (2%) of these children, and three of them (S. flexneri 3a, 1b, and 3a) were identical to the strains from their respective index cases. Compared to children without asymptomatic carriage of shigella (2/166), the risk (odds ratio) of developing diarrhoea for the children with asymptomatic carriage of shigella identical to their cases (3/17) was 9.0 (95% CI 1.5-49.0, P=0.01). The attributable risk for symptomatic shigella infection by intra-familial transmission was 50%. Results of this study demonstrated that intra-familial transmission of shigella carries a higher risk for diarrhoea.     

Clusters of meningococcal disease in France (1987–1988)

We analyzed 814 cases of meningococcal disease notified in 1987 and 1988 to the Ministry of Health. Data were obtained by report forms including informations about possible additional cases among contacts. Coprimary cases (occurring within 24 hours after the index case) and secondary cases (occurring more than 24 hours after index case) were all reviewed.Twenty eight clusters of meningococcal disease were identified involving 65 cases (8% of total cases). Twelve of the 814 cases (1.5%) were coprimary cases of an index case and 25 (3%) were secondary cases. The secondary attack rate was 530/100,000 among household contacts and 31/100,000 among school contacts. Seventy two per cent of the secondary cases occurred in the first week after index case. Thirty-eight percent of the secondary cases occurred in the 15–20 age group as opposed to 15% of single cases. Serogroup A was more often found in coprimary (33%) and secondary cases (17%) than in single cases (6%).In France, prophylaxis of secondary cases is administered to the classroom contacts of a case of meningococcal infection but is not required for the entire school except under epidemic conditions.Corresponding author.     

Bed, bath and beyond: pitfalls in prompt eradication of methicillin-resistant Staphylococcus aureus carrier status in healthcare workers

Healthcare workers (HCWs) in close contact with patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) were screened for MRSA acquisition. From 1995 to 2001, MRSA was identified from the nasopharyngeal swabs of 87 HCWs, collected one to two weeks after contact with 592 known MRSA-positive patients. These HCWs were withdrawn from work and treated with topical antibiotics/antiseptics. They were advised to disinfect their bathrooms and personal hygiene articles, and to wash bed linen and pillows. They were screened for successful eradication for up to three months. Seventy-three (84%) HCWs lost their carrier status. The eradication regimen failed in 14 cases. In 11 of these MRSA was detected only in later nasopharyngeal swabs (suspected recolonization). Screening identified nasal colonization of close household contacts in eight of these 11 cases. Environmental sampling detected contamination in seven out of eight screened home environments. When eradication treatment was applied to household contacts and when household surfaces were cleaned and disinfected, the carriage cleared in most cases within a few weeks. However, when home environments are heavily contaminated, despite adequate medical treatment, eradication took upto two years. Due to withdrawal from work, the 14 carriers without prompt and lasting eradication after the first course of treatment accounted for about 70% of all lost working days. These experiences support the hypothesis that control measures should not be restricted to antibiotic or antiseptic treatment of long-term carriers (HCWs as well as patients), but must also include cleaning and disinfection of the household.     

Pharyngeal carriage of Neisseria meningitidis and Neisseria lactamica in households with infants within areas with high and low incidences of meningococcal disease

In a household survey in the Faroe Islands, an isolated community with hyperendemic occurrence of meningococcal disease due to serogroup B 15, 1604 persons were examined for pharyngeal carriage of Neisseria meningitidis and N. lactamica. Two areas were chosen having experienced high (HIA), and two having experienced low incidences (LIA) of disease. Living in HIA compared with LIA was associated with higher risk of N. meningitidis B 15 carriage and lower risk of N. lactamica carriage, with odds ratios of 2.7 (95% confidence interval (CI) 1.4-5.1, P = 0.003) and 0.41 (95% CI 0.31-0.53, P less than 0.0001), respectively. In HIA the risk of N. meningitidis carriage was much lower in non-carriers than carriers of N. lactamica, with an odds ratio of 0.19 (95% CI 0.08-0.47, P = 0.0003); in LIA this association (odds ratio 0.51, P = 0.05) was much weaker. Children 0-14 years had substantially higher risk of being carriers of N. meningitidis group B 15 if the mothers were so, with an odds ratio of 11 (95% CI 4-29, P less than 0.0001).     

Outbreak of meningococcal disease in western Norway due to a new serogroup C variant of the ET-5 clone: effect of vaccination and selective carriage eradication

A new sulphonamide resistant (SR) C: 15:P1.7,16 meningococcal strain, a variant of the ET-5 clone, dominated in an outbreak of 22 cases in western Norway commencing in 1995. The first eight patients were 15-21 years old from the Nordhordland area, initiating a carrier study in the local high schools. Carriage of SR serogroup C meningococci was detected by routine methods and treated with a single dose of ofloxacin 400 mg. Of 20 treated carriers, 14 harboured the outbreak strain C: 15:P1.7,16. Vaccination of 4000 children, adolescents and close contacts of patients was also performed. After the intervention, 14 additional cases of meningococcal disease occurred, 8 due to the outbreak strain. However, incidence rates dropped from 180 to 30 per 100000 per year in the student population, but increased from 0 to 13 in the rest of the population in Nordhordland. Carriage eradication is not generally recommended in Norway. However, tracing and treating meningococcal carriage may have reduced transmission and disease in this outbreak situation.     

Effectiveness of vaccinating household contacts in addition to chemoprophylaxis after a case of meningococcal disease: a systematic review

SUMMARYWe performed a systematic review to estimate the effectiveness of vaccination, in addition to chemoprophylaxis, in preventing meningococcal disease among household contacts. Medline, EMBASE, EMGM, and EUIBIS were used for data collection. Studies reporting on at least 100 primary cases and on subsequent cases in household settings with follow-up of more than 2 weeks after onset of disease in the primary case were reviewed. A meta-analysis was used to calculate the average attack rate in household contacts given chemoprophylaxis 14-365 days after onset of disease in the primary case. In total, 652 studies were identified, five studies and one unpublished report met the inclusion criteria. The weighted average attack rate was 1.1/1000 household contacts (95% CI 0.7-1.7). This review supports vaccination of household contacts in addition to chemoprophylaxis to reduce the risk of meningococcal disease among household contacts of a case caused by a vaccine-preventable serogroup.     

Asymtomatic carriage of Neisseria meningitidis and Neisseria lactamica in relation to Streptococcus pneumoniae and Haemophilus influenzae colonization in healthy children: apropos of 1400 children sampled

Meningococcal disease is one of the most important causes of morbidity and mortality among children in many parts of the world. Main reservoir of carriage and site of meningococcal dissemination appears to be the upper respiratory tract. Colonization of Neisseria meningitidis and lactamica and factors affecting this carriage were determined in a group of healthy children aged 0–10 years. Meningococcus and N. lactamica carriage were detected in 17 (1.23%) and 245 (17.7%) of 1382 subjects, respectively. Number (%) of serogroups for meningococci was 1 (6), 5 (29), 0 (0), 1 (6), 1 (6), and 9 (53) for A, B, C, D, W135, and Y, respectively. Having more than three household members, elementary school attendance, pharyngeal carriage of Streptococcus pneumoniae and Haemophilus influenzae were associated with carriage of meningococci, whereas age less than 24-month was associated with carriage of N. lactamica. There was a reverse carriage rate between N. meningitidis and N. lactamica by age which may suggest a possible protective role of N. lactamica against meningococcal colonization among pre-school children.     

Risk factors for symptomatic and asymptomatic norovirus infection in the community

The objective of this study was to investigate risk factors for norovirus-associated infectious intestinal disease (IID) and asymptomatic norovirus infection. Individuals with IID and healthy controls were recruited in a community-based study in England (1993-1996). This is the first risk-factor study to use viral load measurements, generated by real-time RT-PCR, to identify cases of norovirus-associated IID and asymptomatic infections. Using multivariable logistic regression the main risk factor identified for norovirus-associated IID was contact with a person with IID symptoms. Infectious contacts accounted for 54% of norovirus cases in young children and 39% of norovirus cases in older children and adults. For young children, contacts outside the household presented the highest risk; for older children and adults, the highest risk was associated with child contacts inside the household. Foreign travel and consumption of shellfish increased the risk of norovirus-associated IID. Lifestyle and dietary factors were associated with a decreased risk of both norovirus-associated IID and asymptomatic infection. No risk factors were identified for asymptomatic norovirus infection.     

Active immunisation during an outbreak of hepatitis A in a German day-care centre

During an outbreak in a German day-care centre (DCC) caring for 100 children HAV vaccination was recommended for children, employees and household members of cases. A retrospective cohort study was done to evaluate vaccine uptake and identify possible risk factors for disease. Between 19 December 2004 and 30 January 2005 eight DCC children and seven household members fulfilled the case definition, i.e. had clinical hepatitis (14) or were diagnosed with asymptomatic HAV infection (1). Following the recommendation to vaccinate, given on 23 December 2004, 66.7% (46/69) of DCC children, 15.8% (29/184) of household members and 5/5 of employees were vaccinated, and three vaccinated children and two not vaccinated children fell ill. One of 11 children who received human normal immunoglobulin (HNIG) and four of 58 children who did not receive HNIG fell ill. In households in which the DCC child received HAV vaccine and/or HNIG, seven (5.6%) of 125 household members fulfilled the case definition. In households of non-immunised children none of the 59 household members fell ill. We conclude that, although most vaccinations were administered promptly, they may not have been timely enough to impact the course of the outbreak.