Disease burden of congenital cytomegalovirus infection at school entry age: study design, participation rate and birth prevalence.

Congenital cytomegalovirus infection (cCMV) may lead to symptoms at birth and long-term consequences. We present a nationwide, retrospective cohort study on the outcome of cCMV up to age 6 years. For this study we identified cCMV, using polymerase chain reaction, by analysing dried blood spots, which are taken shortly after birth for neonatal screening. The group of children with cCMV were compared to a group of children who were cCMV negative at birth. Data were collected about their health and development up to age 6 years. Parents of 73 693 children were invited to participate, and 32 486 (44·1%) gave informed consent for testing of their child's dried blood spot for CMV. Of the 31 484 dried blood spots tested, 156 (0·5%) were positive for cCMV. Of these, four (2·6%) children had been diagnosed with cCMV prior to this study. This unique retrospective nationwide study permits the estimation of long-term sequelae of cCMV up to the age of 6 years. The birth prevalence of cCMV in this study was 0·5%, which is in line with prior estimates. Most (97·4%) children with cCMV had not been diagnosed earlier, indicating under-diagnosis of cCMV.

High risk of a large measles outbreak despite 30 years of measles vaccination in The Netherlands.

Our aim was to assess progress towards measles elimination from The Netherlands by studying humoral measles immunity in the Dutch population. A population-based seroepidemiological study was conducted in 2006-2007 (N = 7900). Serum samples were analysed by a bead-based multiplex immunoassay. IgG levels ⩾0·2 IU/ml were considered protective. The overall seroprevalence in the Dutch population was 96%. However, 51% of socio-geographically clustered orthodox Protestant individuals aged <10 years were susceptible. Infants might be susceptible to measles between ages 4 months and 14 months, the age at which maternal antibodies have disappeared and the first measles, mumps, rubella (MMR) vaccination is administered, respectively. Waning of antibody concentrations was slower after the second MMR vaccination than after the first. The Netherlands is at an imminent risk of a measles outbreak in the orthodox Protestant minority. To prevent subsequent transmission to the general population, efforts to protect susceptible age groups are needed.

Two cases of mild IgM-negative measles in previously vaccinated adults, the Netherlands, April and July 2011.

We describe two cases of mild, modified measles in fully vaccinated adults in the Netherlands. The mildness of disease, the lack of an IgM antibody response, the relatively low amounts of virus detected and the fact that no additional cases were reported, suggests that these vaccinated patients were less contagious than unvaccinated patients.

Mumps epidemic in orthodox religious low-vaccination communities in the Netherlands and Canada, 2007 to 2009.

We assessed the epidemiological characteristics of a mumps virus epidemic (genotype D) that occurred in the Netherlands between August 2007 and May 2009 and its association with a subsequent mumps outbreak in Canada. In the Netherlands, five data sources were used: notifications (only mandatory since the end of 2008) (56 cases), laboratory confirmation data (177 cases), a sentinel general practitioner (GP) database (275 cases), hospitalisation data (29 cases) and weekly virological reports (96 cases). The median age of cases in the notification, laboratory and GP databases ranged from 13 to 15 years. The proportion of cases that were unvaccinated ranged from 65% to 85% in the notification, laboratory and GP databases. Having orthodox Protestant beliefs was the main reason for not being vaccinated. In Canada, a mumps virus strain indistinguishable from the Dutch epidemic strain was detected between February and October 2008 in an orthodox Protestant community with historical and family links to the affected community in the Netherlands, suggesting that spread to Canada had occurred. Prevention and control of vaccine-preventable diseases among population subgroups with low vaccination coverage remains a priority.

Characterization of the human CD8⁺ T cell response following infection with 2009 pandemic influenza H1N1 virus.

The 2009 H1N1 influenza pandemic provided an opportunity to study human virus-specific T cell responses after infection with a novel influenza virus against which limited humoral immunity existed in the population. Here we describe the magnitude, kinetics, and nature of the virus-specific T cell response using intracellular gamma interferon (IFN-γ) staining and fluorochrome-labeled major histocompatibility complex (MHC) class I-peptide complexes. We demonstrate that influenza virus-infected patients develop recall T cell responses that peak within 1 week postinfection and that contract rapidly. In particular, effector cell frequencies declined rapidly postinfection in favor of relatively larger proportions of central memory cells.

Long-term presence of memory B-cells specific for different vaccine components.

Vaccination against infectious diseases ideally should provide lifelong immunity, but in many cases waning of antibody titers has been observed over time. In this study we describe the identification of antigen-specific memory B-cells in peripheral blood of persons born between 1940 and 2004 in The Netherlands. Polyclonal stimulation of either PBMCs or purified B-cells induced proliferation and differentiation of B-cells of the memory phenotype (CD19(+)/CD27(+)) into antibody secreting cells (ASC). Memory B-cells against components of bacterial vaccines (Bordetella pertussis and tetanus) as well as viral vaccines (measles and influenza) were thus identified, even in persons with low serum antibody titers. Enrichment of B-cells increased the sensitivity of memory B-cell detection when compared to PBMCs. Low, but significant correlations between numbers of antigen-specific memory B-cells and the corresponding circulating antibody titers were found for the pertussis proteins and measles virus, but not for tetanus. The identification of the numbers and specificities of peripheral memory B-cells and their relationship with circulating antibodies may be very useful to determine the long-term efficacy of vaccination.

Mumps: not an innocent bystander in solid organ transplantation.

Recently two major outbreaks of mumps have occurred: in the UK more than 56,000 cases were notified between 2004 and 2005, and in the United States, 6,584 cases were reported in 2006. Most patients were young healthy adults, in whom mumps normally has a benign course. Little is known about mumps in the immunocompromised patient. Here, we report a case of a 56-year renal transplant recipient who developed acute irreversible transplant failure due to interstitial nephritis caused by mumps. RNA of the mumps virus was detected in the urine as well as in a renal biopsy. In view of the ongoing presence of the mumps virus in the population, one should be aware of the possible occurrence of this infection in immunocompromised patients.

Feasibility of a rubella screening and vaccination programme for unvaccinated young women.

The feasibility of a rubella screening and vaccination programme for unvaccinated young women was assessed after the 2004/2005 epidemic in The Netherlands. All 640 young women in two villages with low vaccination coverage were invited for a rubella seroprevalence test. Information on vaccination status was gathered by written questionnaire. Women testing seronegative were offered free rubella vaccination. The feasibility of the programme was evaluated in terms of participation, rubella susceptibility, and acceptance of the vaccination offer by seronegative women. The participation rate was 48% [95% confidence interval (CI) 44-52] with 108 unvaccinated participants. Eleven per cent (95% CI 6-19) of the women were identified as susceptible to rubella, of whom 17% (95% CI 2-48) accepted the vaccination offer. In the end only 0.9% (95% CI 0.1-2.5) of the target population was given protection by the programme. Under the present conditions this programme proved to be an inefficient strategy for rubella protection.

[An outbreak of measles at an emergency room]. / Een uitbraak van mazelen op de Spoedeisende Hulp.

A small outbreak of measles occurred after a 33-year-old female aircrew (cabin) member presented at an emergency room with fever. Three members of the hospital staff were infected: a 42-year-old man, a 33-year-old woman, and a 26-year-old woman. The first 2 patients had not been immunised, and the third had received 2 immunisations according to the Dutch National Immunisation Programme. Vaccination of the 2 sero-negative patients within 48 h after exposure with the measles-mumps-rubella vaccine (MMR) did not prevent the development of measles. Vaccination was deemed unnecessary in the third patient. No tertiary cases occurred. The same measles virus (genotype D5) was detected by PCR and sequencing in all 4 patients. Measles remains a risk for hospital staff members who have not acquired natural immunity. The current policy of immunising patients within 72 h after exposure to measles may not be sufficient. It also appears that immunisation through the Dutch National Immunisation Programme does not always protect against nosocomial infection. Providing MMR vaccination or boosters to hospital staff in certain departments might be beneficial.

[Two patients with mumps]. / Twee patiënten met de bof.

Two patients, men aged 17 and 19 years respectively, were admitted with parotitis epidemica and orchitis caused by mumps. The second patient also had meningitis. PCR analysis revealed that, in both cases, the causative agentwas a mumps virus that was genetically related to a wild-type virus responsible for an outbreak in Singapore. This viral strain was also responsible for a mumps outbreak at Hotel School The Hague in September 2004. Both patients were not fully vaccinated. Both patients were from regions in which clustering of patients with clinical signs of mumps has been seen. Interestingly, a number of patients with confirmed mumps had been fully vaccinated. Possible explanations for the increase in mumps cases include low vaccination and immunity levels, primary and secondary vaccine failure and the emergence of genetically disparate mumps viruses.

[Rubella epidemic in the Netherlands, 2004/'05: awareness of congenital rubella syndrome required]. / Rubella-epidemie in Nederland in 2004/'05: alertheid op congenitaal rubellasyndroom vereist.

Rubella is a public health problem due to the teratogenic effects associated with primary rubella infection during pregnancy (congenital rubella syndrome). Following universal rubella vaccination of infants in the Netherlands, the incidence of rubella has declined dramatically. However, since September 2004, an outbreak has occurred among unvaccinated individuals, most of whom declined vaccination based on religious beliefs. In the period 1 September 2004-22 March 2005, 166 cases of rubella were reported, including 12 pregnant women. Monitoring for signs that the epidemic has spread to other populations in the Netherlands is important because this might indicate the need for additional interventions. Awareness among health-care workers of the possible occurrence of congenital rubella syndrome should be raised. The clinical manifestations of congenital rubella syndrome are diverse, can be transient or permanent, and may not present until adolescence or adulthood. All cases of laboratory-confirmed rubella infection and congenital rubella syndrome should be reported to municipal health authorities. There is a possibility that this outbreak will spread abroad. The WHO aims to reduce the incidence of congenital rubella syndrome to < 1/100,000 live births. Health-care workers in the Netherlands should be extra alert to detect and notify rubella in a timely manner.

Measles outbreak in a community with very low vaccine coverage, the Netherlands.

A 1999-2000 measles epidemic in the Netherlands started with an outbreak in an orthodox reformed elementary school with 7% vaccine coverage. The overall attack rate was 37%: 213 clinical cases among the 255 participating pupils (response 62%) and 327 household members. The attack rate ranged from 0% for the oldest groups of pupils to 88% for the youngest, who had not been exposed in previous measles epidemics. None of 25 vaccinated pupils had clinical symptoms. Among pupils with clinical symptoms, the self-reported complication rate was 25%. These data confirm that measles infection causes severe disease and that vaccination is the most effective means of preventing the disease and its complications. The data also show that clusters of persons refraining from vaccination interfere with measles elimination even in populations with very high overall vaccine coverage (96%).

[Measles epidemic in the Netherlands, 1999-2000]. / Mazelenepidemie in Nederland, 1999-2000.

OBJECTIVE: Description of measles epidemic in the Netherlands, 1999-2000. DESIGN: Observational descriptive study. METHODS: Intensified surveillance of measles cases by means of a case register established at the 'Landelijke Coördinatiestructuur Infectieziektebestrijding (LCI)' [National Co-ordination Centre for Communicable Disease Outbreak Management]. RESULTS: There were 3,292 reported measles patients, most of whom came from areas with low vaccine coverage. Of these patients, 94% had not been vaccinated; in 85% of cases this was for religious reasons. Of the 158 (5%) vaccinated patients, 157 had not (yet) received a second dose of vaccine. The incidence of measles increased with decreasing vaccine coverage in a municipality, both for unvaccinated and vaccinated persons. Three of the reported patients died. The percentage of patients with one or more complications was 22% in the group < 15 months of age, 19% in the group 15 months-4 years, 16% in the group 5-9 years, 11% in the group 10-19 years, and 15% in the group > 19 years of age. CONCLUSION: Considering the complications observed, the epidemic described involved a serious disease. Vaccination was accompanied by effective protection against measles infection and its complications. Herd immunity outside the unvaccinated groups was sufficient to prevent an epidemic there. However, incidental spread to vaccinated children did occur; the greatest risk factor for acquiring measles for vaccinated children is a stay in an area with low vaccine coverage.

Transgenic mice expressing human HLA and CD8 molecules generate HLA-restricted measles virus cytotoxic T lymphocytes of the same specificity as humans with natural measles virus infection.

Control of primary measles virus (MV) infection in humans and continued maintenance of immune memory that protects against reinfection are mediated primarily through the anti-MV T cell response, as judged by observations of children with defects in antibody formation but competency in making T cells. Further, the failure of T cell responses in those infected with MV most often leads to overwhelming infection. To better define and manipulate the elements involved in human T cell responses to MV, we analyzed the generation of HLA-restricted cytotoxic T lymphocytes (CTL) in a small animal model. Transgenic mice expressing the human class I MHC antigen HLA-B27 in conjunction with human CD8 molecules produced vigorous HLA-restricted CTL responses to MV antigens, paralleling those in MV infection of humans. In addition, such humanized mice generated human CD8 coreceptor-dependent HLA-B27-restricted CTL with the same specificity for recognition of MV fusion (F) peptide RRYPDAVYL as reported for humans during natural MV infection. Neither murine beta(2)-microglobulin nor murine CD8 substituted adequately as coreceptors for the HLA-B27 heavy chain. By contrast, HLA-A2.1-restricted responses to measles could be generated in the absence of expression of human beta(2)-microglobulin or CD8(+) molecules in HLA-A2.1/K(b) transgenic mice. Thus a small animal model is now available for studying strategies for optimizing human CD8(+) T cell responses and for testing vaccines. This model offers the potential, when combined with the newly reported CD46 transgenic mouse model in which MV replicates in cells of the immune system, for uncoding the molecular mechanism of MV-induced immunosuppression.

Measles in a Dutch hospital introduced by an immuno-compromised infant from Indonesia infected with a new virus genotype.

A fatal measles case in an immunocompromised Indonesian child was associated with nosocomial transmission to health care workers. The virus isolated proved to represent a new genotype within clade G.

Protective immunity in macaques vaccinated with a modified vaccinia virus Ankara-based measles virus vaccine in the presence of passively acquired antibodies.

Recombinant modified vaccinia virus Ankara (MVA), encoding the measles virus (MV) fusion (F) and hemagglutinin (H) (MVA-FH) glycoproteins, was evaluated in an MV vaccination-challenge model with macaques. Animals were vaccinated twice in the absence or presence of passively transferred MV-neutralizing macaque antibodies and challenged 1 year later intratracheally with wild-type MV. After the second vaccination with MVA-FH, all the animals developed MV-neutralizing antibodies and MV-specific T-cell responses. Although MVA-FH was slightly less effective in inducing MV-neutralizing antibodies in the absence of passively transferred antibodies than the currently used live attenuated vaccine, it proved to be more effective in the presence of such antibodies. All vaccinated animals were effectively protected from the challenge infection. These data suggest that MVA-FH should be further tested as an alternative to the current vaccine for infants with maternally acquired MV-neutralizing antibodies and for adults with waning vaccine-induced immunity.

Recycling MHC class I molecules and endosomal peptide loading.

MHC class I molecules usually present peptides derived from endogenous antigens that are bound in the endoplasmic reticulum. Loading of exogenous antigens on class I molecules, e.g., in cross-priming, sometimes occurs, but the intracellular location where interaction between the antigenic fragment and class I takes place is unclear. Here we show that measles virus F protein can be presented by class I in transporters associated with antigen processing-independent, NH(4)Cl-sensitive manner, suggesting that class I molecules are able to interact and bind antigen in acidic compartments, like class II molecules. Studies on intracellular transport of green fluorescent protein-tagged class I molecules in living cells confirmed that a small fraction of class I molecules indeed enters classical MHC class II compartments (MIICs) and is transported in MIICs back to the plasma membrane. Fractionation studies show that class I complexes in MIICs contain peptides. The pH in MIIC (around 5.0) is such that efficient peptide exchange can occur. We thus present evidence for a pathway for class I loading that is shared with class II molecules.