FOOD SAFETY
APHL and CaliciNet: Improving Norovirus
Surveillance and Outbreak Detection
by Kirsten Larson, MPH, manager, Food Safety
CaliciNet is comprised of federal, state
and local public health laboratories that
detect and subtype norovirus strains
associated with gastroenteritis outbreaks
in the US. 1 Created in 2009, CaliciNet
provides a way for the US Centers for
Disease Control and Prevention (CDC)
to compare norovirus strains from
outbreaks and potentially link them to
a common source, monitor circulating
strains and detect emerging ones. 1 APHL
carries out a number of activities to help
increase awareness and participation and
make improvements to this important
network including assisting with training
workshops for local and state public
health laboratorians, coordinating
CaliciNet user group meetings, and
facilitating networking efforts among
member laboratories participating in
CaliciNet Outbreak Support Centers
(OSC) and Unexplained Viral Diarrheal
(UVD) Sites. 2
In fall 2017, APHL worked closely with
members from the California Department
of Public Health (CDPH) Viral and
Rickettsial Disease Laboratory (VRDL),
epidemiologists of CDPH’s Infectious
Diseases Branch and CDC to organize
the 2017 California Norovirus Laboratory
Network Surveillance Meeting. Held
at the CDPH laboratory campus in
Richmond, CA, the meeting brought
together laboratory, epidemiology and
environmental health personnel from
APHL, CDC, CDPH and 34 local health
jurisdictions to explore ways to improve
norovirus testing, surveillance and
outbreak response in California. As one of
five CaliciNet OSCs, CDPH is responsible
for sequencing strains from norovirus
outbreaks from other states and local
CaliciNet provides a way for CDC to compare norovirus strains from outbreaks
and potentially link them to a common source
Rotavirus
health laboratories that are not CaliciNet
certified and uploading those sequences
to the CaliciNet database.
CDPH staff reported several successes
resulting from the meeting. First, multiple
local laboratories expressed interest
in joining the California Norovirus
Laboratory Network (NLN). The NLN is
comprised of the CDPH/VRDL and 24
local public health laboratories capable of
performing real time RT-PCR testing for
norovirus. Second, local epidemiologists
and laboratorians have made a concerted
effort since the meeting to collect stool
specimens during outbreaks. Notably, five
local health departments successfully
obtained specimens for a multinational
norovirus outbreak linked to raw oysters
from British Columbia that sickened ~100
individuals in California alone. Laboratory
testing confirmed norovirus infection in
several of those patients and sequencing
linked them to a common source. Broader
participation across multiple California
counties provides a more comprehensive
picture of predominating norovirus strains
in the US and has provided invaluable
information during outbreaks, leading to
multistate product recalls.
In addition to serving as an OSC, CDPH is
also one of three UVD sites along with the
Minnesota State Public Health Laboratory
Division and Oregon State Public Health
Laboratory. With funding provided
by CDC, the UVD sites are contracted
through APHL to test stool specimens
from norovirus negative outbreaks for
other viral enteric pathogens including
rotavirus, sapovirus, astrovirus and
adenovirus. The positive sequences and/
or PCR data from norovirus-negative
outbreaks from other states are sent
to CDC on a monthly basis. The UVD
sites also send sapovirus, astrovirus
and rotavirus negative samples to
CDC for further analysis and pathogen
discovery. From September 2013–June
2018, the UVD sites and CDC tested 244
https://www.cdc.gov/norovirus/reporting/calicinet/
https://www.aphl.org/programs/food_safety/Pages/CaliciNet.aspx
3
Unpublished outbreak data from CDC and Unexplained Viral Diarrhea study sites.
1
2
28
LAB MATTERS Fall 2018
PublicHealthLabs
@APHL
APHL.org