So Whodunit?

Isn’t it so natural that whenever there is a food borne illness incident the blame is laid squarely at the feet of the last food that was consumed before the symptoms of food poisoning began to emerge.

As a food safety practitioner I have heard again and again, when investigating food borne illness incidents, victims of food borne illness say “it was that mango that I ate in the morning, or it’s was the meal I had in the cafeteria during lunch time, or I shouldn’t have shared in the meat pie so and so was eating…etc etc”. However pointing an accusing finger at the last meal consumed could be misleading.

Firstly, the period between consumption of food and the first signs of illness is termed Onset Period in food safety parlance and it varies from as short as less than an hour to as long as 72 hours depending on a variety of factors.

So to simply assume that the last consumed meal is the culprit of a food borne illness is an oversimplification of how food borne illness plays out.

For instance chemical food borne illness (food borne illness caused by ingesting food contaminated by chemicals) can have a very short onset time (minutes instead of hours) between consumption and illness manifestation as the chemicals gets into the blood stream and circulates swiftly through the blood into the major organs of the body, triggering all forms of symptoms.

On the other hand the onset period of food borne illness caused by pathogenic bacteria could be influenced by amongst many other factors:

1. The time it takes the pathogen to multiply to dangerous levels in the body system.

2. The state of health of the person which has a bearing on the person’s resistance to infections. A sick or convalescing person may manifest symptoms of food borne illness faster than a healthy adult even if they both ate the same contaminated food. This refers to the resilience of ones natural body defenses, i.e. The time it takes for the antibodies to resist the germs before being overwhelmed and succumbing to the infection.

3. The dose (quantity) of the bacteria consumed, which is in turn dependent on the body mass weight of the person. For example children with lower body mass weight can get sickened quicker with a smaller amount of bacteria consumed in food than fully grown adults.

4. The classification of the bacteria i.e. Whether they are toxin forming bacteria (certain bacteria release poisons called toxins into the body system that act faster than a bacterium in causing illness).

From all these factors it can be seen that It is not an impossibility to begin to experience the symptoms of food borne illness several hours, or even days, after consuming contaminated food or drink even if one had eaten other food in the interval.

This has proved true in a number of food borne illness investigations. Typically when investigating incidents of food borne illness, investigators would want to know what and what the victim had eaten in the past 48 or 72 hours. This report will be needed among other reasons, to be compared with the results of causative agent determined from samples collected from the victim in an attempt to identify the culprit food or drink.

For example if the predominant bacteria isolated from feacal samples of a food borne illness victim is Vibrio parahaemolyticus, a food borne illness bacteria commonly associated with seafoods, and the victim had a meal of shellfishes like oysters and clams 3 days earlier and hadn’t eaten any such related foods thereafter, it’s is most likely that is the source of the food borne illness even if the victim had eaten other meals in the interval.

So…before passing a guilty verdict on the last meal that was eaten as being the cause of the food borne illness, further thought should be given to other meals that had been eaten down the line.

More Than Meets The Eye

“there is more to food borne illness than the frequent commute to the toilet or to the local pharmacy down the street.”

In many quarters in this country, the outcome of a person with food borne illness is simply viewed as having the nasty and unpleasant symptoms of diarrhea, vomiting, nausea, tiredness, stomach upsets for a period of time after which recovery sets in with or without medical treatment and the victim gets back on with life. Or, less acknowledged, outright death and fatality of victims.

But there is an ominous and little known aspect of food borne illness that began to be considered some five years ago which may aggrandize the public health burden of food borne illness globally, Nigeria inclusive. This is the Long-Term Health Outcomes of Selected Foodborne Pathogens.

The Center for Foodborne Illness Research & Prevention (CFI), a US based non profit research and advocacy organization, released a report in 2009 that placed the spotlight on the long-term health consequences of five foodborne illnesses pathogens: Campylobacter, E. coli O157:H7, Listeria monocytogenes, Salmonella, and Toxoplasma gondii.

According to the report, serious life-long complications like hemolytic uremic syndrome (HUS), the leading cause of acute kidney failure in children; paralysis; seizures; reactive arthritis; hearing/visual impairments and mental retardation have been associated one way or the other with these food borne pathogens.

To read the full report click here: CFI LTHO REPORT

Even though the authors of the report acknowledged that “this long-term health burden of foodborne disease is not well understood” and “additional research is needed to improve our knowledge about these diseases”. The study counters the common public perception that food borne illness is basically limited to the symptoms previously mentioned above and in rare cases fatalities.

That is to say there is more to food borne illness than the frequent commute to the toilet or to the local pharmacy down the street.

A 2012 case of a 7 year old girl that was left brain damaged and paralyzed from food poisoning in Australia sort of validates the hypothesis raised in the CFI report. To read the full story of this incident click here: Girl Paralyzed By Food Poisoning Traced To KFC Chicken

The implication of this for Nigerians is that our public health system, inadequate and already getting overwhelmed as it is, will yet have to cope with additional burden if the food borne illness problem isn’t addressed as a matter of great priority.

A pragmatic preventative approach to address the problem of food borne illness in this country through enforcing existing food safety legislations, Local Governments rising up to their statutory responsibilities of food business inspections, and most importantly continually creating public awareness about the food borne illness problem to counter the dearth of public awareness of this problem will spare our public health management system additional burdens that it simply cannot bear at this moment.

Know Thine Enemy & Know Thyself

Know Thyself & Know Thine Enemy

Sun Tzu

In the fight against food-borne illness, *Sun Tzu’s quote “know thine enemy and know thyself” is a good dictum to follow.

Why? Because in numerous kitchens (commercial kitchens, domestic kitchens in homes, and even communal village open-space kitchens) across the length and breadth of this country, the bugs that cause food-borne illness have been doing a lot of damage to the health and well-being of the public, and places considerable burden on the public health in Nigeria. Aided by ignorance of the populace, these pathogens seem to be having a field day. To turn the tide of this fight, folks need to know these germs, know how they infect, know the foods they are commonly associated with, know how they affect human health, and know how they can be curbed.

I have tried to profile five important food borne illness causative bugs in Nigeria in simple layman’s language as part of increasing awareness of these bugs, how they operate, and how they can be checkmated.

1. Vibrio Cholerae – Count for count, this food borne & water-borne bug has done more damage to public health in Nigeria than any other food borne illness bug.

To understand this check out my posts of 7th December and 22nd December titled 2013 Cholera Outbreak and Chronicling Cholera’s Carnage Parts 1 & 2 respectively.

Vibrio cholerae, the bug that causes cholera, is transmitted by consuming contaminated water or food washed or prepared with contaminated water or food prepared by a person sick with cholera.

Once the bug gets into the intestine of its victims it multiplies rapidly and secretes cholera toxin, it’s the toxin that does the damage by causing the intestine to release plenty of fluid that leads to its trademark symptoms; a sudden onset of watery stools and diarrhea. If not quickly treated the victims loose a lot of fluid from the body and die from dehydration. The suddenness of the watery stools and diarrhea is the characteristic of vibrio cholerae.

Hand-washing practices, properly boiling water before use, cooking food thoroughly, proper environment sanitation, use of latrines and toilets instead of open defecating are all ways of countering this bug.

2. Salmonella Spp – Salmonella bacterium is another major cause of food borne illness in Nigeria. The bug is transmitted by eating contaminated foods especially food of animal origin  i.e meat, poultry, eggs, milk. However fresh produce and vegetables have also been implicated in salmonella outbreaks. The bug gets into the food chain from infected livestock and animals where the livestock has been fed with salmonella contaminated animal feed. Fresh produce are contaminated when they are irrigated with sewage water containing salmonella or fertilized with animal manure of infected animals.

Food implicated in salmonella food borne illness in Nigeria are eggs (cracked eggs & eggs smeared with feaces), edible snails, roasted chicken sold by roadside vendors, improperly cooked chicken, local soft cheese “wara”, unpasteurized (raw) milk sold as fura-de-nunu, local sandwich and local salad. The salmonella bug was isolated in fillings from sandwiches that caused an outbreak of food borne illness in Ibadan that claimed about 20 lives some years ago.

In healthy adults the bugs needs to be consumed in large numbers to cause illness, but in the young and elderly a small dose is enough to cause trouble. Even though majority of the ingested bug gets destroyed in the stomach by gastric acid, the ones that survive and pass into the intestine and multiplies there resulting in the symptoms of diarrhea, fever, nausea, vomiting and stomach cramps usually between 12 – 72 hours after ingesting the bug. The illness may last 4-7 days. Serious forms of the illness can lead to fatality when the bugs spread from the intestines to the blood stream and then to other body organs especially in the young, elderly, or the sick.

Cooking food at temperatures at 75C for is sufficient to kill the bugs. Other means of preventing the bug from infecting is by avoiding cross contamination of the bug from raw food to other food i.e. not using same utensils (chopping boards, knives, work surface) for raw foods and ready to eat foods without thoroughly washing with soap and hot water, separating raw foods from ready to eat food in storage in fridge, ensuring proper cleanliness in the kitchen, and thorough washing and sanitizing fresh produce before eating.

3. Listeria monocytogenes – A contaminant found in Nigerian foods like smoked fish, kilishi (sun-dried & partially roasted seasoned meat slices), kununzaki (fermented sorghum drink), wara (local soft cheese popular in South West Nigeria), and unpasteurized (raw) milk sold as fura-de-nunu, Listeria monocytogenes, the bug that causes Listeriosis also referred to as L.Mono, is an uncanny food borne illness bug. Uncanny in the sense that unlike most food borne illness causing bugs, L.Mono can survive and even grow at temperature as low as 0C such that it multiplies even when food is refrigerated.

Naturally existing in soil, water and vegetation from where it gets into the food chain, L.Mono can be destroyed in food by proper cooking and pasteurizing. It’s symptoms are diarrhea, vomiting, nausea, fever, and muscle aches which may begin to manifest as short as few hours to as long as 3 months after ingestion (for the very severe type). Where you see the normal symptoms of food borne illness accompanied with aches at the knees and elbows as well as stiff neck, it’s probably L.Mono at work.

Healthy adults are rarely affected by L.Mono, it’s aged/elderly persons, pregnant women, newborns, and adults with weakened immune systems that are the groups mostly at risk of this bug. And of this group pregnant women are the highest number of its victims where the bug passes from the intestine into the blood and becomes blood borne affecting the fetus resulting in miscarriage or stillbirth.

Infection by L.mono can be prevented by cooking food thoroughly to safe temperatures, by washing and proper handling of food before eating, keeping kitchen environment clean, proper handwashing, separating raw food from ready to eat food, avoiding cross contamination, and avoid eating the high risks foods as listed above.

4. Staphylococcus aureus – This bug by itself is harmless and occurs naturally on skin, hair as well as nose and throats of humans and animals. However when it gets into food it rapidly multiplies and secretes very potent toxins into the food. The major source of contamination is from food handlers and food preparers.

Once it has multiplied and produced the toxins into the food, heating treatment or cooking of the food makes no difference anymore because the toxins are very heat stable and are not easily destroyed by heat. So cooking food that has been colonized by staph aureus may destroy the bugs themselves but the toxins survive and when the food is eaten the toxins cause the illness with symptoms of vomiting, diarrhea, nausea and stomach pains typically one to six hours after ingestion of the toxin and this may last between 24 – 48 hours before it subsides.

Staph aereus need time to multiply in food to the dangerous levels that are sufficient to cause illness. Leaving food unrefrigerated for a short period gives it the chance to do this.

Moi-Moi (bean pudding), Agidi (Fermented Corn Meal), Abacha (African Salad), Suya (Roasted Meat) and similar hand prepared meals are examples of Nigerian foods implicated in staph food borne illness.

Ways to prevent staph infection are avoiding time and temperature abuse of food, proper handwashing before food preparation, not allowing food handlers (and children’s nannies & caregivers) with open sores/boils/wounds/long fingernails/skin infections/nose & eye infection to prepare food, avoid coughing and sneezing unto food, eating food immediately after preparation, rapid chilling and cold storage of food to prevent multiplication of the bug in food.

5. Aspergillus flavus – Aspergillus flavus, unlike the previous four bugs above, is not a bacteria but a fungus found in food like maize, groundnuts, sorghum, groundnuts that produce poisonous toxin. This toxin can be very dangerous when ingested and cause aflatoxicosis. It has been reported to causes liver cancer, suppresses the immune system, and retards the growth and development of children.

Even though the toxin is invisible to the naked eye, the bugs can be discerned in crops by a characteristic mould green color.

Prevention of aflatoxicosis begins at the farm by treating the crops to kill the bugs and also during storage. Infected crops are usually destroyed to prevent human consumption. However some of these infected crops inevitably enters the food chain as Agidi, the peanut paste used to prepare Kilishi, Kuli-Kuli (local snack made from fermented groundnut), Yaji (the spice that accompanies Suya) and when livestock eat feed contaminated with Aspergillus flavus.

The toxins produced by the Aspergillus bug are not affected by routine cooking temperatures, but simple food preparation methods such as sorting, washing, crushing, and dehulling may reduce aflatoxin levels (Public Health Strategies for Preventing Aflatoxin Exposure 2005).

These five food borne illness pathogens, along with other such pathogens not profiled in this post, have collectively brought a huge burden on the public health system of this country.

*Sun Tzu was a Chinese general, military strategist, and author of The Art of War, an immensely influential ancient Chinese book on military strategy. (Source: