678. Determinants of Varicella Occurrence and Disease Severity in Household Contacts
Session: Abstracts: Virology
Friday, October 22, 2010
Background: Varicella is a highly infectious disease with household transmission rates of 60-100%. Factors associated with transmission and severe disease are not well described.

Methods: Using multilevel logit models, we analyzed primary and secondary case characteristics by household using data from the Varicella Active Surveillance Project, Antelope Valley, CA, 1997-2001.  A primary case was the first case in a household. A secondary case was a case occurring 10 to 21 days after the primary case in the household. We restricted analysis to household contacts aged 1-14 years due to low predictive value of a negative varicella history among adults and likelihood of maternally acquired antibody in infants.

Results: Within households, the occurrence of secondary varicella cases was associated with exposure to a primary case with ≥50 lesions (odds ratio (OR) = 1.71, P<0.001), household size ≤5 people (OR=1.37, P=0.003), household contact aged ≤10 years (OR=1.57, p=0.004) or within 4 years of age of the primary case (OR=1.87, P<0.001). Secondary cases were more likely to have been exposed to a primary case with >500 or 50-500 lesions vs. ≤50:  OR=2.18, 1.67; P<0.001, respectively. Among secondary cases with no history of varicella vaccination or prior disease, those with more severe varicella (rash with ≥50 lesions) were more likely to be >10 years old (OR=3.13, P=0.02), be within 4 years of age of the primary case (OR=1.69, P=0.02), live in households < 5 people (OR=1.38, P=0.03), and be exposed to a primary case with ≥50 lesions (OR=3.45, P<0.001).

Conclusion: Primary case characteristics and intensity of exposure were determinants of transmission and disease severity. These characteristics may be useful for identifying primary cases more likely to result in transmission and for limiting exposures among susceptible individuals at risk for severe varicella disease for whom vaccination is contraindicated.


Subject Category: I. Adult and Pediatric Vaccines

Speakers:
Chengbin Wang, PhD , Centers for Disease Control and Prevention, Atlanta, GA
Rachel Civen, MD , Acute Communicable Disease Control Program, Los Angeles, CA
John Zhang, PhD , Centers for Disease Control and Prevention, Atlanta, GA
Adriana Lopez, MHS , Centers for Disease Control and Prevention, Atlanta, GA
Stephanie R. Bialek, MD, MPH , Division of Viral Diseases, Centers for Disease Control and Prevention, Atlanta, GA

Disclosures:

C. Wang, None

R. Civen, None

J. Zhang, None

A. Lopez, None

S. R. Bialek, None

See more of: Virology
See more of: Abstracts

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 21 with the exception of research findings presented at IDSA press conferences.

 
 
   
 

Copyright IDSA 2009 Infectious Diseases Society of America 1300 Wilson Boulevard, Suite 300 Arlington, VA 22209 info@idsociety.org