Related Experiment Videos
Immunologic and epidemiologic aspects of varicella infection acquired during infancy and early childhood
Insights
Varicella zoster virus (VZV) infection occurred in 100% of susceptible infants. Infants under two months experienced milder disease, but maternal antibodies did not prevent infection or immune response.
Area of Science:
- Immunology
- Virology
- Pediatrics
Background:
- Varicella zoster virus (VZV) causes chickenpox, a common childhood illness.
- Infant immune systems are still developing, making them vulnerable to infections.
- Understanding VZV infection dynamics in infants is crucial for public health strategies.
Purpose of the Study:
- To investigate the development and clinical presentation of VZV infection in infants under one year of age.
- To assess the role of pre-existing maternal antibodies in VZV infection susceptibility and severity.
- To evaluate the immune response to VZV infection in different infant age groups.
Main Methods:
- Prospective study of infants during three VZV outbreaks in a Japanese institution.
- Testing for cutaneous reactivity to VZV antigen and VZV-specific antibody levels.
- Clinical observation and documentation of varicella development and severity.
Main Results:
- An overall attack rate of 100% was observed in susceptible infants.
- Infants under 2 months experienced milder cutaneous involvement (less than 20 vesicles).
- Severe cutaneous disease (over 300 eruptions) was more frequent in infants aged 2-11 months.
- Pre-existing maternal antibodies did not prevent infection or alter the immune response.
Conclusions:
- All susceptible infants in the study population contracted VZV infection.
- Infant age influences the severity of varicella, with younger infants showing milder symptoms.
- Maternal antibodies offer limited protection against VZV infection and subsequent immune responses in infants.
Abstract:
The development of varicella zoster infection was studied in a population of infants under one year of age during three outbreaks of varicella in a semi-closed domiciliary institution for infants in Japan. Over a period of four years, many residents ranging in age from 27 days to 32 months were tested for cutaneous reactivity to VZV antigen, and VZV-specific antibody activity before, during, and after each outbreak of varicella. Of these, 85 subjects developed clinical varicella, with an overall attack rate of 100% for all susceptible subjects. All the infants under 2 months of age were infected following such exposure, despite the presence of pre-existing maternal antibody. The degree of cutaneous involvement appeared to be milder (less than 20 vesicles) in infants less than 2 months of age, and severe cutaneous disease (with over 300 eruptions or confluent rash) occurred more frequently in subjects 2 to 11 months of age. Pre-existing antibody did not prevent development of illness, or alter the degree of antibody or cellular immune response to subsequent infection. However, the peak cutaneous reactivity to VZV antigen after infection was found to be significantly lower in infants under 2 months of age.