INTRODUCTION
INTRODUCTION
A foodborne disease outbreak is defined as two or more illnesses caused by the same germ (e.g. a toxin, virus or bacteria) which are linked to consuming the same contaminated food or drink .
Foodborne illness is a common, costly, sometimes life threatening yet largely preventable public health problem.
According to the Centers for Disease Control and Prevention (CDC), approximately 1 in 6 Americans (or 48 million people) get sick, 128,000 are hospitalized, and 3,000 die of foodborne diseases. Only a small portion of those are related to foodborne disease outbreak. The number of cases reported to the health department are much smaller in comparison to the actual number of foodborne illnesses that occur each year. [6]
Most of the outbreaks and foodborne illnesses are caused by consuming two most common types of foodborne pathogens: [7]
Bacteria, like Salmonella, Listeria, or E. coli
Viruses, such as norovirus or hepatitis A
According to the CDC (Centers for Disease Control and Prevention), some of the common symptoms of a foodborne illness include:
upset stomach
abdominal cramps
nausea
vomiting
diarrhea
fever
dehydration
Symptoms may range from mild to severe and differ depending on the agent that caused the illness, the duration the agent has been present in your system and how well your immune system can fight back. Some illnesses lead to long-term health problems or death. [8]
Foodborne disease outbreaks can occur in a variety settings such as Restaurant meal, school/university cafeteria, church potluck and so on. If the outbreak occurs after a specific event then the local health department in that area would be responsible for investigating the outbreak. When the outbreaks involve residents from multiple states such as when the food has been distributed regionally or nationally then the it is harder to investigate and falls under the 'Multistate' category.
Public health department in all 50 states, the District of Columbia, U.S. territories, and Freely Associated States have primary responsibility for identifying and investigating outbreaks and use a standard form to report outbreaks voluntarily to CDC. During 1998–2008, reporting was made through the electronic Foodborne Outbreak Reporting System (eFORS) [9]
Foodborne pathogens are responsible for enormous number of illnesses with significant effects on public health and economy. As mentioned earlier, foodborne illnesses are largely avoidable if the appropriate actions are taken. To this end, it is imperative to identify, select and implement mitigation strategies in order to govern and reduce these risks. [5]
In this study I will be examining the Foodborne disease illnessess in the USA between 1998 and 2015. This study aims at answering questions such as, which regions are most affected by foodborne illnessess, what are the common species of toxins, what food items are most prone to contamination, how have the foodborne outbreaks evolved over the years and so on.
[Data source for all graphs: https://www.kaggle.com/cdc/foodborne-diseases]
This is a choropleth map of US displaying the total number of outbreaks, hospitalizations, illnesses, and fatalities per state.
It is clear that California is the most affected state by foodborne diseases. While Delaware has the least number of illnesses which could be only because it is one of the smallest states.
California and Florida states have consistently been among the top states when it comes to the number of illnesses. We could attribute that to the weather. Since these are relatively warmer states, the chances of food contamination is higher as it creates favorable conditions for the toxins. It is a commonly known fact that bacteria grow most rapidly between the temperatures of 40 ° and 140 °F, doubling in number in as little as 20 minutes. Alternatively, these states could simply have higher cases due to higher number of population. [1]
However, it is seen that California, Florida, Michigan, Maryland, Washington, and Pennsylvania have all decreased their illness rates significantly over the years. The reason for this could be the introduction of new State Health and Sanitation laws.
As mentioned earlier, Multistate cases are the those outbreaks that involve residents of multiple states caused due to the food being distributed across borders.
The graph above illustrates that 2010 had the highest number of multistate illnesses as well as outbreaks
2011 had the highest number of multistate fatalities, while 2004 and 2005 have negligible fatalities
Highest number of hospitalizations were seen in 2008
Even though some states have managed to successfully lower the number of illnesses over the years, the number of multistate foodborne illnesses have been relatively rising since 2002 with a few exceptions.
It is important to track the evolution of foodborne diseases over the years to understand it's advancement.
According to this time-series analysis, outbreaks and illnesses have shown significant decrease in the number of cases until 2009. Following which, they have remained steady (13k-15k cases) with slight increase in 2015.
Number of hospitalization cases had two major peaks in 2006 and 2008 which are consistent with the peaks we saw in the multistate graph earlier. Again the number of cases seems to have rise in 2015 after a slight dip in 2014.
2011 saw a spike in fatalities which is consistent with the information we got from the multistate graph, so we can attribute this spike to multistate fatalities.
After considering this time-series analysis, it could be concluded that foodborne diseases are occurring less frequently now. However, it is not possible to say that with certainty as many diseases go unreported or undiagnosed.
Seasonality could be a contributing factor to foodborne disease outbreaks.
Outbreaks seem to be highest in the months of May-June and again November-December. This is also the case with the number of illnesses which are highest in the months between April-June and November-December. As November and December, are festive periods of the year, which involve large number of parties, markets and other festive events this is completely understandable.
Hospitalizations are highest in June-July following the outbreak peaks. Fatalities are also highest in July with a second peak in October.
This graph displays the top most contaminated location and food pairings. It is evident that some of the top locations such as restaurants, catering services, prisons/jails and school/colleges/universities are all places where food is not prepared by the consumer and is cooked in large quantities. Thus, increasing the chance of contracting a foodborne illness.
The types of food seems to be varying from dairy, to meat and vegetables, making it difficult to positively categorize them as high risk. We could conclude that location is a more compelling factor when it comes determining food contamination as compared to the actual food.
Some ingredients are more prone to getting contaminated compared to others. After taking a look at the data, it was discovered that Meat is an easily contaminable food group, followed by eggs and vegetables. Basically, raw foods of animal origin, raw meat and poultry, raw eggs, unpasteurized milk, and raw shellfish are the most likely to be contaminated.
Meat and poultry could be easily polluted during the slaughter by the intestinal contents of the animal.
Fresh fruits and vegetables are at risk of contamination if they are washed with dirty water. They can also be contaminated with animal waste if manure is used to fertilize the fields. [2][3]
It is observed that Norovirus I, Salmonella enterica and Norovirus II, were responsible for over 50% of the foodborne outbreaks and illnesses in the US between 1988 and 2015. According to the FDA, Norovirus is the most common cause of foodborne illness across the US. Not only does it spread by consuming contaminated food or water but can also spread easily from person-to-person. [4]
The leading causes of fatalities were found to be Salmonella enterica, Norovirus II and Staphylococcus aureus. Therefore, it can be said that while Norovirus I is a leading pathogen for outbreaks and illnesses, it is not as fatal as Salmonella enterica and Norovirus II.
The following insights can be drawn from the above visualizations:
California, Illinois, Florida, Ohio and New York are ranked as the top 5 States when it comes to Foodborne illnesses.
California, Florida, Michigan, Maryland, Washington, and Pennsylvania have all decreased their illness rates significantly over the years.
The regions with least number of illnesses are ranked as - Republic of Palau, Guam, Delaware, Vermont and South Dakota.
2010 had the highest number of multistate illnesses as well as outbreaks. The highest number of multistate fatalities were observed in 2011, while 2004 and 2005 have negligible fatalities. Multistate hospitalizations were greatest in 2008.
Outbreaks and illnesses have shown significant decrease in the number of cases until 2009. Following which, they have remained steady (13k-15k cases) with slight increase in 2015.
After considering this time-series analysis, it could be concluded that foodborne diseases are occurring less frequently now.
Outbreaks seem to be highest in the months of May-June and again November-December. This is also the case with the number of illnesses which are highest in the months between April-June and November-December.
Hospitalizations are highest in June-July following the outbreak peaks. Fatalities are also highest in July with a second peak in October.
Some of the top most contaminated locations include restaurants, catering services, prisons/jails and school/colleges/universities.
In general, raw foods of animal origin, raw meat and poultry, raw eggs, unpasteurized milk, and raw shellfish are the most likely to be contaminated.
It is seen that Norovirus I, Salmonella enterica and Norovirus II, caused over 50% of the foodborne outbreaks and illnesses in the US between 1988 and 2015.
https://www.health.state.mn.us/people/foodsafety/prevention.html
https://www.health.state.mn.us/diseases/foodborne/basics.html
https://www.fda.gov/files/food/published/Most-Common-Foodborne-Illnesses-%28PDF%29.pdf
https://www.fda.gov/files/food/published/Most-Common-Foodborne-Illnesses-%28PDF%29.pdf