Wednesday, February 23, 2011

Gastroenteritis Outbreaks

This month nearly half of the student body at one Ohio elementary school was infected with the norovirus (see: Fox News). There was a Norvovirus outbreak in Fanling, Hong Kong (see press release). One international cruise ship reported an incidence too (see report). There were many less documented cases (according to one of the recent sufferers, "you go to Facebook and everyone’s status is either ‘sick’ or ‘recovering’"). Almost every hour someone twits about stomach that hurts or other signs of food poisoning.

How are gastrointestinal outbreaks defined?

Food-borne disease outbreak is an incident in which two or more persons experience a similar illness after ingestion of a common food or meal.

Waterborne outbreaks may be associated with drinking water or with recreational water.

Non-foodborne, non-waterborne outbreaks are defined as two or more cases of illness related by time and place in which an epidemiologic evaluation suggests either person-to-person transmission occurred or a vehicle other than food or water (e.g., animal contact) is identified. This category also includes outbreaks for which the route of transmission could not be determined.

Better detection of gastrointestinal outbreaks is possible if crowdsourcing is utilized. |For example, in 1998, the toll-free MDH foodborne illness hotline (1877-FOOD-ILL) was implemented in Minnesota. In 2005, 35 (85%) of the 41 confirmed foodborne outbreaks were initially reported to MDH or local public health agencies via phone calls from the public; the remaining six outbreaks were identified through active laboratory-based surveillance for bacterial pathogens.
According to Minnesota Department of Health (see Outbreak Statistics: Summary of Gastroenteritis Outbreaks in Minnesota) of the 41 confirmed foodborne outbreaks, 28 (68%) were either laboratory-confirmed (n=26) or epidemiologically defined (n=2) outbreaks of norovirus gastroenteritis. There were five (12%) confirmed foodborne outbreaks caused by Salmonella, one (2%) caused by E. coli O157:H7, one (2%) caused by scombroid toxin, and one (2%) caused by escolar toxin. The remaining five confirmed foodborne outbreaks (12%) were classified as bacterial intoxications (caused by Clostridium perfringens, Staphylococcus aureus, or Bacillus cereus).

Norovirus is a leading cause of food-borne disease outbreaks in the United States.

The importance of norovirus as a cause of foodborne disease outbreaks in 2005 continues a pattern that has been observed for over two decades in Minnesota. During 1981-2005, 291 (50%) of 586 confirmed outbreaks of foodborne disease were due to norovirus, while 118 (20%) confirmed foodborne outbreaks were caused by infectious bacterial pathogens such as Salmonella and E. coli O157. Therefore, over this 25-year period the combined number of foodborne outbreaks due to infectious bacterial agents was less than half the number of foodborne outbreaks due to norovirus.
Many outbreaks of norovirus are due to ill food workers handling ready-to-eat food items such as salads and sandwiches in restaurant or catering settings. In other foodborne norovirus outbreaks, ill or convalescent individuals contaminate shared food (e.g., self-serve food items in a wedding reception buffet or school cafeteria). Prevention of further disease transmission during norovirus outbreaks is accomplished by emphasizing good handwashing procedures, minimizing bare-hand contact with ready-to-eat food items, minimizing environmental contamination, and excluding ill employees from work until 72 hours after recovery.
There were five confirmed foodborne outbreaks caused by Salmonella in 2005. Two of the outbreaks were associated with commercially distributed, frozen, stuffed, microwaveable chicken entrees. One salmonellosis outbreak was associated with cake batter ice cream sold at a national retail ice cream chain and involved cases in multiple states. One salmonellosis outbreak was linked to pork or cilantro sold at grocery stores. One salmonellosis outbreak was associated with a restaurant. The causes of restaurant outbreaks of salmonellosis are often complex and can involve consumption of undercooked foods of animal origin, infected foodhandlers, cross-contamination between raw and ready-to-eat foods, environmental contamination, and inadequate cooking, hot holding, cooling, and reheating of multiple food items.
MDH identified one foodborne outbreak caused by E. coli O157:H7 in 2005. This outbreak was associated with prepackaged, prewashed lettuce salad that was distributed to multiple states.
Five of the confirmed foodborne outbreaks identified in Minnesota in 2005 were bacterial intoxications caused by pathogens such as Clostridium perfringens, Bacillus cereus, and Staphylococcus aureus. These outbreaks often lack laboratory confirmation, as the resulting illnesses typically are of short duration. A recurring theme in outbreaks of bacterial intoxications is improper time and temperature control of potentially hazardous food items such as meats, rice, and sauces.
There were four waterborne gastroenteritis outbreaks identified by MDH in 2005. All involved recreational water; three were associated with lake beaches and one with an indoor swimming pool. The three outbreaks associated with lake beaches had a known etiology (E. coli O157:H7, Shigella sonnei, and norovirus, respectively).
There were 39 non-foodborne, non-waterborne outbreaks of gastroenteritis identified in 2005. The majority of outbreaks in this category were associated with person-to-person transmission of enteric pathogens, predominantly norovirus, in nursing homes, schools, daycares, and other facilities. For reasons that are unclear, most norovirus outbreaks in nursing homes occur during the winter months.

Today FDA approved marketing of Ridascreen Norovirus 3rd Generation assay - first test for gastroenteritis outbreaks. Not sensitive enough for individuals, this screening procedure could be used when a number of people have simultaneously contracted gastroenteritis, for identification of food-borne disease outbreaks.

The Ridascreen Norovirus 3rd Generation EIA assay is for use when a number of people have simultaneously contracted gastroenteritis and there is a clear avenue for virus transmission, such as a shared location or food.

We are still a while away from getting it under control, but t's good to see progress. Hopefully there will be more developments in diagnostics tools and better crowdsourcing platforms.


Sunday, February 20, 2011

Flu update: Have we passed the peak?

According to WHO, the highest influenza rates were in Asia, with notable increases in respiratory disease activity in Singapore and Hong Kong, and the majority of cases tested positive for 2009 H1N1. Influenza activity appears to have peaked in the majority of North African and Middle Eastern countries with the exception of Algeria, where rates increased. The percentage of respiratory specimens testing positive for influenza was also high in Pakistan, Iran and Oman. Influenza cases in southern China decreased from its peak earlier this season.Although influenza activity was sparse in the tropical Americas and sub-Saharan Africa, it increased in Madagascar. Influenza activity remained low in the temperate Southern Hemisphere.
 According to the Public Health Agency of Canada, influenza activity increased slightly, but remained below the peak observed earlier this season.

In US, the following ILI activity levels were experienced:
  • Twenty-one states (Alabama, Arkansas, California, Colorado, Georgia, Hawaii, Idaho, Illinois, Indiana, Kansas, Louisiana, Missouri, New Jersey, New Mexico, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and West Virginia) experienced high ILI activity.
  • Six states (Alaska, Arizona, Connecticut, Massachusetts, Pennsylvania, and Utah) experienced moderate ILI activity.
  • New York City and 16 states (Delaware, Florida, Kentucky, Maryland, Minnesota, Mississippi, Nebraska, Nevada, New York, North Dakota, Ohio, Oregon, South Dakota, Washington, Wisconsin, and Wyoming) experienced low ILI activity.
  • Minimal ILI activity was experienced by seven states (Iowa, Maine, Michigan, Montana, New Hampshire, Rhode Island, and Vermont).
    Click on map to launch interactive tool


In Europe, activity moved past its peak, although it was still intense in Luxembourg, Georgia and the Siberian region of the Russian Federation (source).


Intensity Geographic
Spread
Impact Sentinel
swabs
Percentage
positive
Dominant
type
ILI per
100,000
ARI per
100,000
Sentinel
SARI
Virology graph
and pie chart
AlbaniaHighLocalModerate375.4%None

494.3 (graphs)
Click here
ArmeniaMediumLocalModerate50%None0.0 (graphs)91.2 (graphs)


sari
Click here
AustriaMediumWidespreadLow6965.2%Type A, Subtype pH1N10.0 (graphs)35.2 (graphs)
Click here
AzerbaijanLowSporadicLow220%None314.2 (graphs)


Click here
BelarusMediumLocalModerate2951.7%Type A, Subtype pH1

1756.0 (graphs)
Click here
BelgiumMediumWidespread
5062.0%Type B and Type A, Subtype pH1N1328.2 (graphs)1573.2 (graphs)
Click here
Bosnia and Herzegovina




Type A, Subtype pH1
(graphs)


Click here
BulgariaMediumRegional
1070.0%Type A, Subtype pH10.0 (graphs)1339.0 (graphs)
Click here
CroatiaHighWidespreadLow

Type A, Subtype pH1221.2 (graphs)


Click here
CyprusLowLocalLow


1.5 * (graphs)8.0 * (graphs)
Click here
Czech RepublicMediumWidespread
2982.8%Type A, Subtype pH1N1226.1 (graphs)1435.3 (graphs)
Click here
DenmarkMediumWidespread
3813.2%None (graphs)0.0 (graphs)
Click here
EnglandLowSporadic
9614.6%Type A and B12.1 (graphs)390.9 (graphs)
Click here
EstoniaMediumWidespread
4015.0%Type A, Subtype pH118.4 (graphs)437.3 (graphs)
Click here
Finland
Widespread
4833.3%Type B and Type A, Subtype pH1N10.0 (graphs)0.0 (graphs)
Click here
FranceMediumWidespreadLow17545.7%Type B and Type A, Subtype pH1N10.0 (graphs)2369.6 (graphs)
Click here
GeorgiaVery HighWidespreadSevere4893.8%Type B and Type A, Subtype pH11454.7 (graphs)




sari
Click here
GermanyMediumRegional
24250.8%Type A, Subtype pH1N10.0 (graphs)1309.0 (graphs)
Click here
GreeceHighWidespread
3759.5%Type A, Subtype pH1N1399.9 (graphs)0.0 (graphs)
Click here
HungaryMediumWidespreadModerate14311.9%Type A, Subtype pH1475.6 (graphs)0.0 (graphs)
Click here
IcelandMediumRegionalModerate00%
75.2 (graphs)0.0 (graphs)
Click here
IrelandMediumRegionalLow4731.9%Type B36.2 (graphs)0.0 (graphs)
Click here
IsraelMediumWidespreadModerate4134.2%Type A and B35.0 (graphs)


Click here
ItalyHighWidespreadModerate11355.8%Type A, Subtype pH1N1768.5 (graphs)0.0 (graphs)
Click here
KazakhstanMediumLocalModerate1492.9%None1.9 (graphs)365.9 (graphs)


sari
Click here
KyrgyzstanLowSporadicLow1060.0%Type A and B8.6 (graphs)45.9 (graphs)


sari
Click here
LatviaMediumWidespread
933.3%Type B (graphs)


Click here
LithuaniaHighWidespreadLow


85.8 (graphs)660.7 (graphs)
Click here
Luxembourg


5858.6%Type B and Type A, Subtype pH1 (graphs)


Click here
MaltaLowLocalLow


9.2 * (graphs)0 * (graphs)
Click here
NetherlandsMediumWidespread
3253.1%Type B60.4 (graphs)0.0 (graphs)
Click here
Northern IrelandLowSporadic
1010.0%Type B29.9 (graphs)359.2 (graphs)
Click here
NorwayLowWidespread
742.9%Type B and Type A, Subtype pH1120.0 (graphs)0.0 (graphs)
Click here
PolandMediumRegional
10223.5%Type A, Subtype pH1171.8 (graphs)0.0 (graphs)
Click here
PortugalLowSporadic
30%Type A, Subtype pH131.5 (graphs)0.0 (graphs)
Click here
Republic of MoldovaMediumLocalModerate8457.1%Type B and Type A, Subtype pH1N127.0 (graphs)470.0 (graphs)


sari
Click here
RomaniaHighWidespreadModerate3083.3%Type B and Type A, Subtype pH1N141.6 (graphs)1260.4 (graphs)


sari
Click here
Russian FederationHighWidespreadModerate6639.4%Type A, Subtype pH138.4 (graphs)1096.3 (graphs)


sari
Click here
ScotlandLowLocalLow4522.2%Type B2.2 (graphs)253.2 (graphs)
Click here
SerbiaHighRegionalModerate1100.0%Type A, Subtype pH1N1204.6 (graphs)




sari
Click here
SlovakiaMediumLocalLow2365.2%Type A, Subtype pH1487.9 (graphs)2514.5 (graphs)
Click here
SloveniaMediumWidespread
2365.2%Type B and Type A, Subtype pH169.6 (graphs)1499.3 (graphs)
Click here
SpainMediumRegional
24631.7%Type B113.6 (graphs)0.0 (graphs)
Click here
SwedenHighWidespreadLow3327.3%Type B19.5 (graphs)0.0 (graphs)
Click here
SwitzerlandMediumWidespread
6576.9%Type B and Type A, Subtype pH1276.8 (graphs)


Click here
TurkeyMediumLocalModerate10740.2%None
(graphs)


Click here
UkraineMediumLocalLow425.0%Type A and B5.2 * (graphs)674.7 (graphs)


sari
Click here
WalesLowSporadicLow


6.2 (graphs)0.0 (graphs)
Click here
Europe


229142.2%




Click here