Sources of infection among persons with acute hepatitis A and no identified risk factors during a sustained community-wide outbreak.
BACKGROUND
Hepatitis A is a common vaccine-preventable disease in the United States. Most cases occur during community-wide outbreaks, which can be difficult to control. Many case-patients have no identified source.


OBJECTIVE
To identify foodborne and household sources of hepatitis A during a community-wide outbreak.


METHODS
Serologic and descriptive survey.


METHODS
Salt Lake County, Utah.


METHODS
A total of 355 household contacts of 170 persons reported with hepatitis A during May 1996 to December 1996, who had no identified source of infection; and 730 food handlers working in establishments where case-patients had eaten.


METHODS
Prevalence of immunoglobulin M antibodies to hepatitis A virus (IgM anti-HAV) among household and food service contacts.


RESULTS
Overall, 70 household contacts (20%) were IgM anti-HAV-positive, including 52% of children 3 to 5 years old and 30% of children <3 years old. In multivariate analysis, the presence of a child <3 years old (odds ratio [OR]: 8.8; 95% confidence limit [CL]: 2.1,36) and a delay of >/=14 days between illness onset and reporting (OR: 7. 9; 95% CL: 1.7,38) were associated with household transmission. Of 18 clusters of infections linked by transmission between households, 13 (72%) involved unrecognized infection among children <6 years old. No food handlers were IgM anti-HAV-positive.


CONCLUSIONS
During a community-wide outbreak, HAV infection among children was common, was frequently unrecognized, and may have been an important source of transmission within and between households. Transmission from commercial food establishments was uncommon. Ongoing vaccination of children may prevent future outbreaks.
Staes
C J
CJ
Salt Lake City-County Health Department, Salt Lake City, Utah, USA. catherine.staes@hsc.utah.edu
Schlenker
T L
TL
Risk
I
I
Cannon
K G
KG
Harris
H
H
Pavia
A T
AT
Shapiro
C N
CN
Bell
B P
BP
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D016358:Contact Tracing; D004196:Disease Outbreaks; D018562:Disease Transmission, Infectious; D005192:Family Health; D005260:Female; D005511:Food Handling; D006506:Hepatitis A / Q000453:epidemiology / Q000208:ethnology / Q000635:transmission*; D035922:Hepatitis A Antibodies; D017957:Hepatitis A Virus, Human / Q000276:immunology; D006508:Hepatitis Antibodies / Q000097:blood; D006801:Humans; D018445:Infectious Disease Transmission, Vertical; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D014589:Utah / Q000453:epidemiology
D035922:Hepatitis A Antibodies; D006508:Hepatitis Antibodies