Parotiditis en Chile: caracterización clínica y molecular de dos casos en una población altamente inmunizada / Parotiditis in Chile: clinical and molecular characterization of two cases in a highly vaccinated population

Resumen El virus de la parotiditis produce una infección benigna caracterizada por un aumento de volumen parotídeo que, antes de la introducción de la vacuna tres vírica, afectaba principalmente a niños y adolescentes. Luego de que esta vacuna se implementara en el Programa Nacional de Inmunizaciones, se produjo una notable disminución en su incidencia. Además, ocasionó un cambio en la edad y presentación clínica, siendo más frecuente en adultos jóvenes con mayor riesgo de complicaciones. Presentamos dos casos clínicos de parotiditis en adultos jóvenes confirmados por serología y en uno de ellos, por biología molecular. Se caracterizó el virus como del genotipo G, como el descrito en los brotes en E.U.A y Europa, diferente al virus contenido en la vacuna. El virus parotídeo sigue circulando en nuestro país y debemos mantenernos alerta ante eventuales brotes. Se hace relevante optimizar el diagnóstico etiológico por serología o técnicas de biología molecular con fines clínicos y epidemiológicos.

Mumps virus usually produces a benign infection characterized by increased parotid volume which, prior to vaccination, mainly affected children and adolescents. After the introduction of measles, mumps and rubella (MMR) vaccine, mumps incidence decreased dramatically. This intervention also produced a change in its clinical presentation, moving to young adult patients, with an increased risk of complications. We report two clinical mumps cases in young adults with different clinical presentations. In both cases, serologic assays were assessed and, in one case, a polymerase chain reaction (PCR) was performed in order to confirm the diagnosis. The isolated virus was characterized and identifed as G genotype, the same genotype observed during outbreaks in United States and Europe, and different to the vaccinal strain. Mumps virus is currently circulating in Chile and it is important to be aware of possible outbreaks. Viral diagnosis can be difficult, particularly in populations with high vaccination coverage. Therefore, the access to etiologic study through PCR and serology becomes more relevant in order to optimize clinical management and secondary prevention measures.

Seroprevalence of antibodies to measles, mumps, and rubella among Thai population: evaluation of measles/MMR immunization programme.

Stored serum specimens, from four regions of Thailand, of healthy children attending well baby clinics and of healthy people with acute illnesses visiting outpatient clinics were randomly sampled and tested for IgG antibody to measles, mumps, and rubella (MMR). The immunity patterns of rubella and mumps fitted well with the history of rubella and MMR vaccination, seroprotective rates being over 85% among those aged over seven years. A high proportion of younger children acquired the infection before the age of vaccination. MMR vaccination should preferably be given to children at an earlier age. For measles, 73% seroprotective rates among children, aged 8-14 years, who should have received two doses of measles/MMR vaccine, were lower than expected. This finding was consistent with the age-group reported in outbreaks of measles in Thailand. The apparent ineffectiveness (in relation to measles) of MMR immunization of 1st grade students warrants further studies.

A randomized comparative trial in order to assess the reactogenicity and immunogenicity of a new measles mumps rubella (MMR) vaccine when given as a first dose at 12-24 months of age.

An open, randomized multi-center trial, involving 700 infants, was conducted in order to compare a new measles mumps rubella (MMR) vaccine, SB MMR (containing a Jeryl Lynn derived mumps strain RIT 4385) with a widely used vaccine, Merck MMR, when given to children between 12-24 months. Infants were divided between 2 groups; group 1 received SB MMR while group 2 received Merck MMR. Solicited local and general symptoms were recorded using diary cards and antibody levels were measured using ELISA assays. There was a significantly lower incidence of redness (p < 0.001) and swelling (p = 0.03) observed in group 1 compared with group 2. The incidence of all other solicited local and general symptoms were comparable between groups. In initially seronegative subjects equivalent seroconversion rates and post-vaccination GMTs were observed between groups. In conclusion, these results demonstrate that SB MMR is safe and well tolerated when given to children at this age range, and has an equivalent immunogenic profile compared to the widely used Merck MMR vaccine.

Evaluation of serological status of rubella & mumps in children below five years.

A cross-sectional study was carried out on 321 serum samples to detect rubella and mumps antibodies in children below five years and to assess the optimum age for immunization against rubella and mumps. Seropositivity to rubella was 33.3 per cent in children below nine months, 16.9 per cent at 9-12 months and 25.5 per cent by two years. Mean antibody levels for rubella were low at nine months to one year and remained so till five years of age. Similarly, seropositivity for mumps was 53.3 per cent below nine months, 20.3 per cent at 9-12 months and 40 per cent by two years. Mean antibody levels for mumps were low between nine months to two years with a slight rise by five years. The findings suggest that a large majority of children are at risk by the age of nine months in our population and the measles, mumps and rubella (MMR) vaccination at this age may be most beneficial.

Efficacy of two dose measles vaccination in a community setting.

OBJECTIVE: To compare the efficacy of two dose and single dose measles vaccination in a community setting. DESIGN: Two community ICDS blocks with populations of 8990 and 8550 children below 12 years of age were selected. Block A had 1560 children between 9 mo to 1 year of age and Block B had 1380 children between the age of 9 mo to 1 year. METHODS: All eligible children between 9 mo to 1 year of age were given measles vaccination in October 1994. Only the children in Group A were given a second dose of measles (as MMR) in April 1995; six months after the first dose. A survey was undertaken from January 1996 to April 1996 to clinically evaluate the number of cases of measles in both these blocks. RESULTS: In Block A 3 children developed measles, whereas in Block B, there were 16 cases of measles (p < 0.01). All other parameters in both groups, e.g., cold chain maintenance were similar. CONCLUSION: This study supports the superiority of two dose measles vaccination given at an interval of 6 months over a single dose measles in a community setting.

Immunogenicity and reactogenicity of indigenously produced MMR vaccine.

OBJECTIVES: To study immunogenicity and reactogenicity of indigenously produced MMR vaccine and to assess the booster effect of MMR immunization on measles seroconversion. DESIGN: A longitudinal follow up. SETTING: Hospital based and home follow up, as required. SUBJECTS: 89 children already immunized for measles, between 15 to 24 months of age for immunogenic evaluation and 866 subjects for the reactogenic component. METHODS: Prevaccination and postvaccination samples collected one and four weeks after vaccination were studied by ELISA for IgG and IgM antibodies against the three diseases. A clinical follow up of immunized children was done at 3 days, 7 days, 6 weeks and 6 months after immunization. RESULTS: IgG positivity 4 weeks after immunization rose from 75% to 100% for measles, from 12% to 92% for mumps, and from 13% to 99% for rubella. Only mild side effects including pain and swelling in 37 (4.3%) cases, mild fever in 51 (5.9%) cases, cough in 40 (4.6%) cases and a transient rash in 7 (0.8%) cases were observed. CONCLUSIONS: The indigenously manufactured MMR vaccine has an excellent immunogenicity and low reactogenicity with a booster effect for measles seroconversion in children already immunized for this disease.

Vacuna contra la parotiditis / Vaccine against mumps

La parotiditis es una enfermedad infecciosa aguda causada por un virus que por lo general afecta a las glándulas parótidas y ocasionalmente a otros órganos y sistemas; clínicamente se le reconoce como una inflamación de las glándulas salivales. Es un padecimiento autolimitado y casi siempre de curso benigno que afecta primordialmente a los niños y adultos jóvenes. La primera vacuna antiparotiditis que se aplicó en humanos fue en 1950, con una preparación de virus inactivado con formol. Los primeros estudios con esa vacuna demostraron que tenía una tasa de protección del 80 por ciento, que se mantenía por tiempo corto y por lo tanto se requería de revacunaciones cada año, por lo que no se logró su aceptación. En 1967 se aceptó una nueva vacuna atenuada, producida a partir de un virus aislado de una paciente, que se atenuó a través de 27 pasos en embriones de pollo. Esta vacuna induce anticuerpos neutralizantes protectores en el 93 y 97 por ciento de adultos y niños vacunados, respectivamente. La persistencia de anticuerpos es de unos 20 años cuando se aplica sola, ya que también se produce combinada con las vacunas de sarampión y de la rubéola en cuyo caso los anticuerpos se producen en menor cuantía y con duración de 9.5 años