Encephalitis lethargica (EL) was first reported in 1917 in central Europe. It became epidemic in the winter of 1918/1919 concurrently with the pandemic of influenza, and by then had reached Russia and North America. It spread throughout the world in epidemic form, mainly in the succeeding winters, up to 1927. By then about 65 000 cases had been reported, although the true number worldwide can only be guessed at. EL mortality was about 30% in the acute stage, and similar during recurrences. Half of the survivors had persistent or recurrent neuro-psychiatric illness, with Parkinsonism a frequent end stage. Most contemporary observers attributed EL to a virus and some believed it was specifically a post-influenzal complication. The epidemiology of EL mostly points to an infective cause, e.g. a seasonal respiratory or gastrointestinal virus with infrequent encephalitic expression but the ability to persist, flare and progressively damage the brain. However, any link with the influenza virus strain of 1918/1919 remains hypothetical. The aetiological theories that have been applied to EL are reviewed and the question is raised whether broader laboratory investigation might now reveal a continuing low endemicity of EL and identify its cause.

Avian influenza caused infection and spread throughout Nigeria in 2006. Carcass samples (lung, liver, spleen, heart, trachea and intestine) from the different regions of Nigeria were processed for virus isolation. Infective allantoic fluids were tested for avian influenza viruses (AIV) and Newcastle disease virus using monospecific antisera. Thirty-five isolates were generated and characterized molecularly using the haemagglutinin gene. The molecular analysis indicated that different sublineages of the highly pathogenic avian influenza (HPAI) H5N1 viruses spread throughout Nigeria. We compared the Nigerian isolates with others from Africa and results indicated close similarities between isolates from West Africa and Sudan. Some of the analysed viruses showed genetic drift, and the implications of these for future epidemiology and ecology of avian influenza in Africa require further evaluation. The spread of primary outbreaks was strongly linked to trade (legal and illegal), live bird markets, inappropriate disposal, and poorly implemented control measures. No strong correlation existed between wild birds and HPAI H5N1 in Nigeria.

Specimens for the detection of avian influenza virus (AIV) were collected from 1937 waterfowl on the Wexford Sloblands, a major wetland reserve in southeast Ireland, between January 2003 and September 2007. During the same period, 1404 waterfowl were sampled at other locations in Ireland. Specimens were tested either by virus isolation or real-time reverse transcriptase polymerase chain reaction (rtRT–PCR). A total of 32 isolates of AIV, comprising nine subtypes, was obtained from specimens from the Sloblands compared with just one isolate from elsewhere in Ireland. Samples from nine other waterfowl, five of which were from the Sloblands, tested positive for AIV by rtRT–PCR. Ecological factors are likely to have contributed to the higher detection rate of AIV at the Sloblands compared with the rest of Ireland. It was concluded that targeted surveillance at such sites is a cost-effective means of monitoring the circulation of new AIVs in waterfowl, whereas widespread opportunistic sampling is unproductive and wasteful of resources.

We analysed long-term epidemiological trends in influenza-like illness (ILI) in The Netherlands and used an ecological analysis to estimate its relationship with age, influenza vaccination, and virological aspects. This study used data from weekly ILI consultation reports from sentinel general practitioners (1986/1987 to 2006/2007), virological data from sentinel ILI patients (1992/1993 to 2006/2007), and data for influenza vaccine uptake (1991–2005). The incidence of ILI consultations, although varying during the study period, was estimated to decrease in the total population by 12·2/10 000 persons each season (95% CI 8·6–15·9). Uptake of influenza vaccination in people aged ⩾65 years (elderly) increased from 28% in 1991 to >70% since 1997. ILI incidence in the elderly declined by 1·7/10 000 persons (P=0·05) per percentage vaccine uptake per season. The decline in ILI incidence over the last 20 years could be related to the increased vaccine uptake. However, insufficient data were present to assess the impact of other potential contributing factors, such as diminished fitness of influenza viruses and changes in consulting behaviour.

The European Sero-Epidemiology Network 2 (ESEN2) aimed to compare serological results of vaccine-preventable diseases across Europe. To ensure direct inter-country comparability of hepatitis A virus antibody (anti-HAV) measurements, a standardization panel of 150 sera was developed by a designated reference laboratory and tested by participating national laboratories using assays of choice; each country's results were subsequently regressed against those of the reference laboratory. Quantitatively, the assays were generally highly correlated (R2>0·90). Nevertheless, qualitative comparisons indicated that results obtained with different assays may differ despite the usage of well-established international and local standards. To a great extent standardization successfully alleviated such differences. The generated standardization equations will be used to convert national serological results into common units to enable direct international comparisons of HAV seroprevalence data. The results of this study are expected to contribute to the evaluation and potential improvement of the currently employed immunization strategies for hepatitis in Europe.

In the Dutch national vaccination campaign for behavioural risk groups, anti-HBcore is used as the primary HBV screening test. Samples with positive results undergo testing for active infection (HBsAg) but are otherwise accepted as indicating past infection, thereby assuming immunity. This study evaluated evidence for immunity in the target population screened on the basis of this algorithm, by re-analysing 1000 anti-HBcore-positive blood samples equally divided among risk groups: 14·7% of confirmed anti-HBcore lacked anti-HBs (‘isolated’ anti-HBcore). Independent risk factors for isolated anti-HBcore were risk group, HCV infection in hard-drug users (DU) and origin from Sub-Saharan Africa. After extrapolation, the proportion of participants who were said to be immune but lacked any additional evidence of immunity amounted to 9·6% (ranging from 12·5% in DU to 6·5% in men who have sex with men). It is recommended that as a minimum anti-HBs screening is included in testing algorithms used to determine vaccination programmes for risk groups, in particular in DU.

The impact of hepatitis B vaccination in men having sex with men in Amsterdam has been marginal until now, possibly because of increases in sexual risk behaviour counterbalancing the effect of vaccination. A mathematical model is used to describe the hepatitis B epidemic. The model shows that, with the current vaccination coverage, the decrease in incidence is small in the beginning. However, the number of infections prevented per vaccine administered rises over time. Nevertheless, increased risk behaviour reduces the benefit of vaccination. Targeting high-risk men is more successful in reducing and containing the epidemic than targeting low-risk men. In conclusion, the vaccination campaign is effective and should be intensified. High-risk men should be targeted for vaccination and for risk reduction.

Matching individuals reported to a sentinel surveillance scheme for hepatitis C between 2000 and 2005 to individuals with a hospital episode for hepatitis C-related liver disease in the same hospitals, we estimated that the number of cases of hepatitis C-related end-stage liver disease in these English hospitals was 42% (597/419) higher than Hospital Episode Statistics (HES) would indicate. Further, matching records of hepatitis C-related deaths in HES to death certificates, we estimated that, between 2000 and 2005, the true number of deaths from hepatitis C-related end-stage liver disease was between 185% (353/124) and 257% (378/106) higher than the number recorded in routine mortality statistics. We provide estimates of under-recording that can be used to modify existing models of disease burden due to hepatitis C and provide a simple approach to improve the monitoring of trends in severe hepatitis C-related morbidity over time.

Varicella is a very common childhood disease responsible for an important number of hospitalizations every year in Spain. The aim of this study was to assess the burden of chickenpox hospitalizations in Spain in the 7-year period between 1999 and 2005. Data of hospital discharges relating to varicella were obtained from the Conjunto Mínimo Básico de Datos (CMBD), the Spanish surveillance system for hospital data. All paediatric hospitalizations for primary varicella that occurred between 1 January 1999 and 31 December 2005 were selected. The hospitalization rate for the 7-year study period was 23·06 hospitalizations/100 000 population. The highest incidences of hospitalizations were observed in the youngest groups (60·79 and 55·65/100 000 population for ages 0–12 months and 1–2 years respectively). Nineteen deaths were reported during the study period. The median length of stay in hospital was 4 days (interquartile range 3–7 days). Despite the availability of effective varicella vaccines, chickenpox remains an important cause of hospitalizations in Spain.

A serological survey was used to investigate the epidemiology of cytomegalovirus (CMV) infection in England and Wales. A total of 5237 sera representing the complete age range were used reflecting the general population. The sera were collected in 1991 and 2002, and screened for CMV-specific IgG by ELISA. Antibody prevalence increased with age from ~15% in those aged 1–4 years to ~80% in those aged ⩾65 years with no association with gender or region. Analysing by common birth cohort demonstrated that between 1991 and 2002 incidence was highest in children born 1985–1989 (1·62% per year, 95% CI 0·86–2·35), lower in older children and younger adults born 1950–1984 (0·75% per year, 95% CI 0·29–1·19) with little evidence of infection in older adults born pre-1950 (0% per year, 95% CI 0–0·64). Application to population and live-birth estimates for England and Wales suggested that between 1991 and 2002, 159 996 (95% CI 67922–278277) CMV infections occurred annually with an annual average of 2133 (95% CI 816–3435) infections affecting pregnant females.

In April 2005, an outbreak of Chikungunya fever occurred on the island of Réunion in the Indian Ocean. During winter 2005, six patients developed meningoencephalitis and acute hepatitis due to Chikungunya virus. Our objectives were to determine the incidence and mortality of atypical Chikungunya viral infections and to identify risk factors for severe disease. A hospital-based surveillance system was established to collect data on atypical Chikungunya cases. Case reports, medical records and laboratory results were reviewed and analysed. We defined an atypical case as one in which a patient with laboratory-confirmed Chikungunya virus infection developed symptoms other than fever and arthralgia. We defined a severe atypical case as one which required maintenance of at least one vital function. We recorded 610 atypical cases of Chikungunya fever: 222 were severe cases, 65 affected patients died. Five hundred and forty-six cases had underlying medical conditions (of which 226 suffered from cardiovascular, 147 from neurological and 150 from respiratory disorders). Clinical features that had never been associated with Chikungunya fever were recorded, such as bullous dermatosis, pneumonia, and diabetes mellitus. Hypertension, and underlying respiratory or cardiological conditions were independent risk factors for disease severity. The overall mortality rate was 10·6% and it increased with age. This is the first time that severe cases and deaths due to Chikungunya fever have been documented. The information presented in this article may assist clinicians in identifying the disease, selecting the treatment strategy, and anticipating the course of illness.

Between 1979 and 2000, foxes constituted the main reservoir of rabies in the Northern regions of Israel. Following the implementation of the fox-targeted oral vaccination programme (ORV) in 1998, rabies was eradicated from this area. Subsequently during 2004–2007, the biological and molecular characterization of the rabies isolates showed that stray dogs emerged as the main animal reservoir in Northern Israel while lower numbers of cases were reported in domestic animals. The virus isolates from foxes and dogs differed, in their molecular characterization, suggesting two distinct separate lineages. The transition from fox-mediated rabies to dog-mediated rabies is of great concern to public health because of the close contact between dogs and the human population.

In this study, two sheep, eight dromedary camels and two Bactrian camels were inoculated with foot-and-mouth disease virus (FMDV) type A SAU 22/92. Five naive dromedary camels and four sheep were kept in direct or indirect contact with the inoculated camels. The inoculated sheep, which served as positive controls, displayed typical moderate clinical signs of FMD and developed viraemia and high antibody titres. The presence of the virus was also detected in probang and mouth-swab samples for several days after inoculation. In contrast, the inoculated dromedary camels were not susceptible to FMDV type A infection. None of them showed clinical signs of FMD or developed viraemia or specific anti-FMDV antibodies despite the high dose of virus inoculated. All the contact sheep and contact dromedaries that were kept together with the inoculated camels remained virus-negative and did not seroconvert when tested up to 28 days post-inoculation (p.i.). In comparison with the non-susceptible dromedaries, the two inoculated Bactrian camels showed moderate to severe clinical signs of FMD; however, the clinical signs of FMD appeared rather late, between 8 and 14 days p.i., compared to the inoculated sheep. Characteristic FMD lesions in the Bactrian camels, accompanied with severe lameness, were only observed on the hind feet. The presence of the virus in the serum samples of both Bactrian camels was detected by real-time RT–PCR in one of the animals on days 3 and 7 p.i. and in the second animal from days 1 to 3 p.i. and subsequently again on day 21 p.i. The Bactrian camels developed high titres of antibodies to the inoculated FMDV which appeared at 7–10 days p.i. and lasted up to 130 days p.i. Only low and transient amounts of FMDV were detected in the mouth-swab and probang samples collected from both Bactrian camels.

This study aimed to identify risk factors and assess the impact of coincidental antibiotic therapy on carriage of Streptococcus pneumoniae. Index children from birth to 3 years and their households were recruited from primary health-care registers in four UK general practices. Nasopharyngeal swabs were taken monthly from study participants ten times between October 2001 and July 2002. Multilevel random-effect models were used to adjust for statistical dependence between repeated measurements and family clustering of carriage. Carriage results were available for 3753 swabs from 489 individuals in 121 families. Crude prevalence of carriage was 25%. On multivariable analysis, risk of carriage was reduced by antibiotic use the previous month [odds ratio (OR) 0·34, 95% confidence interval (CI) 0·22–0·52], but increased if a child attended day care for >20 h per week (OR 2·52, 95% CI 1·41–4·52). Taking antibiotics significantly reduces the risk of carriage the following month in a setting with a low prevalence of pneumococcal antimicrobial resistance.

We studied the incidence of invasive pneumococcal disease (IPD) in the Czech Republic by analysing two sources of data. The incidence of pneumococcal meningitis based on routine notification data varied between 0·4 and 0·6/100 000 population between 1997 and 2006. The incidence of IPD based on laboratory surveillance varied between 2·3 and 4·3/100 000 population between 2000 and 2006. The annual IPD incidence remained stable during the study period. Estimates of absolute IPD case-load in the entire country varied from 235 to 437 per year. The age-specific incidence was highest in the <1 year age group, reaching 4·3/100 000 for pneumococcal meningitis in routine notification and 15·7/100 000 for IPD in laboratory-based surveillance data, respectively. A total of 1236 Streptococcus pneumoniae isolates from cerebrospinal fluid and sterile body sites were investigated. The most frequent serotypes causing IPD in all ages were 3, 4, 14, 8 and 19F, accounting for 41·5% of all isolates. The most frequent serotypes by age group were: <1 year (6B and 19F); 1–4 years (14, 6B and 23F); 40–64 years (3, 8 and 4), and ⩾65 years (3, 4, 9N and 14). The coverage of serotypes in all age groups by pneumococcal vaccines ranged from 41·5% for 7-valent conjugate vaccine to 67·9% for 13-valent conjugate vaccine. The coverage of serotypes causing IPD is significantly different between infants/children and adults/elderly. PCV-7 coverage by age group was: <1 year (66·0%), 1–4 years (65·1%), 40–64 years (34·4%) and ⩾65 years (39·3%). Similar age differences between infants/children and adults/elderly were found in coverage by PCV-9, PCV-11 and PCV-13. The distribution of serotypes in the total population and individual age groups was stable during the period 2000–2006.

The first of several cases of meningococcal meningitis was reported in April 2005, in New Delhi, India. Subsequent to this the Government declared an outbreak, which persisted for two periods, from April–July 2005 and January–March 2006. The National Institute of Communicable Diseases (NICD) recommended using WHO criteria for diagnosis of disease. During the outbreak 380 clinically suspected cases were investigated. Of 55 cases diagnosed as confirmed/probable the mortality rate was 14·6%. Meningitis was reported in 60% of cases and meningococcaemia in 40%. Microscopy of petechial rash was positive in 87·5%, CSF Gram stain positive in 68·3%, and latex agglutination test of CSF positive in 64·9% of samples. Neisseria meningitidis (serogroup A) was isolated from 37·7% of cases, 57·7% from CSF. Blood culture was positive in 10·4% of cases. CrgA polymerase chain reaction for N. meningitidis confirmed the isolates. All isolates were susceptible to third-generation cephalosporins, azithromycin and rifampicin, with increasing resistance to ceftriaxone. Penicillin resistance was encountered in 15·4% of strains. Resistance to quinolones was very high at 100% for levofloxacin, 84·6% for ofloxacin and 65·4% for ciprofloxacin. All patients with penicillin-resistant organisms (4) or intermediate sensitivity (4) succumbed to the disease. These patients also had a higher minimum inhibitory concentration to ceftriaxone.

During the 11-year period from 1997 to 2007, 321 isolates of Listeria monocytogenes from sporadic cases of invasive listeriosis were reported to the national reference laboratory in Israel. Of these isolates, 113 (35%) were identified from perinatal cases, and 208 (65%) from non-perinatal cases. The prevalent serovars were 4b, 1/2b, 1/2a and 4c. Serovar 4b was identified in 80·5% of the perinatal isolates (P=0·0162), while the number of 1/2b and 1/2a strains increased in the ⩾60 years old group (P=0·0285). Resistance to tetracycline was found in eight 4b isolates. The seasonal distribution showed that 206 isolates (64·2%) were submitted during the hot season (May–October). The estimated morbidity for the study period was 4·4 per million. The incidence of invasive listeriosis was higher in the perinatal group (5·6/100 000), than in individuals aged ⩾60 years (1·5/100 000).

We report an objective examination of nosocomial transmission events derived from long-term (10-year) data from a single medical centre. Cluster analysis, based on the temporal proximity of genetically identical isolates of the respiratory pathogen Moraxella catarrhalis, identified 40 transmission events involving 33 of the 52 genotypes represented by multiple isolates. There was no evidence of highly transmissible or outbreak-prone genotypes. Although most clusters were small (mean size 3·6 isolates) and of short duration (median duration 25 days), clustering accounted for 38·7% of all isolates. Significant risk factors for clustering were multi-bed wards, and winter and spring season, but bacterial antibiotic resistance, manifested as the ability to produce a β-lactamase was not a risk factor. The use of cluster analysis to identify transmission events and its application to long-term data demonstrate an approach to pathogen transmission that should find wide application beyond hospital populations.