| Food poisoning is an acute illness caused by the | | | | the bacteria and the excretion of toxins give rise to |
| consumption of contaminated food. In the case of | | | | the abdominal cramps. It is thought that a lot of the |
| bacterial food poisoning, it would require several | | | | pain, fever and other inflammatory symptoms are the |
| hundred thousand or a million bacteria to cause illness. | | | | result of the immune system in action, and not caused |
| Foodborne disease is caused by bacteria and some | | | | by the action of the bacteria, viruses or toxins. |
| viruses that give rise to similar symptoms as food | | | | Diarrhoea is the final stage of the bacterial clean-out. |
| poisoning, but only a few bacteria or viral particles are | | | | Some scientists believe that diarrhoea is another |
| required, sometimes as few as five. They are also | | | | phase initiated by the brain to expel the invaders; some |
| called low dose pathogens. | | | | believe it is the action of bacteria on the colon to |
| Examples of Foodborne disease agents are: E coli, | | | | release them as quickly as possible in order to |
| Campylobacter, Listeria, Norovirus, Shigella, Typhoid, | | | | proliferate outside the body. Darwin's theory of the |
| Cholera, Hepatitis A. The main symptoms of food | | | | survival of the fittest can be demonstrated here. |
| poisoning and Foodborne disease are nausea, vomiting, | | | | Charles Darwin published "On The Origin of Species |
| stomach cramps and diarrhoea. There are other | | | | by Means of Natural Selection" in 1859. In it he |
| symptoms with some of the bacteria such as fever, | | | | proposed: |
| general malaise, prostration, etc. The symptoms are | | | | 1 Within a given species, more individuals are produced |
| the body's self-defence mechanisms leaping into | | | | by reproduction than can survive within the constraints |
| action. In our throat, oesophagus and stomach, we | | | | (e.g. food supply) imposed by the species' environment. |
| have chemoreceptors, which detect any undesirable | | | | 2 Consequently, there is a struggle for existence, |
| chemicals. Some of these undesirable chemicals are | | | | because of the disparity between the number of |
| present on the "skin" of the bacteria or viruses. The | | | | individuals produced by reproduction and the number |
| receptors inform the brain, in particular an area in the | | | | that can survive. |
| brain termed the "vomiting centre" The brain relays | | | | 3 Individuals within a species show variation; no two |
| messages to the oesophagus, giving a feeling of | | | | individuals are exactly alike (not even those referred to |
| nausea, and to the stomach to instruct it to expel all | | | | as 'identical' twins). Those with advantageous |
| contents (vomit). We have another line of defence, the | | | | characters have a greater probability of survival, and |
| hydrochloric acid produced by specialised cells in the | | | | therefore of reproducing, in the struggle for existence. |
| stomach, parietal cells. The acid will kill most microbes, | | | | 4 Individuals produce offspring that tend to resemble |
| apart from acid tolerant ones such as E coli or ones | | | | their parents (the principle of inheritance). Provided that |
| that are protected by food particles. That is why | | | | the advantageous characters that promote survival |
| pre-biotic bacteria will not work; they are immediately | | | | are inherited by offspring, individuals possessing those |
| killed by the gastric fluid. In order for pre-biotics to work, | | | | characters will become more common in the |
| they would have to reach the small intestine. It has | | | | population over successive generations because they |
| been estimated that you would have to drink 11 litres of | | | | are more likely than individuals not possessing those |
| pre-biotic drink, in one go, for some of the "good | | | | characters to survive and produce offspring in the |
| bacteria" to overcome the stomach acid and reach | | | | next generation. |
| the small intestine! | | | | Cholera and Typhoid, for example, would not be able |
| Sometimes the acid tolerant pathogens and the ones | | | | to proliferate and drive their species forward, unless |
| that escaped the acid bath onslaught reach the small | | | | out of the body and infecting other hosts. It is therefore |
| intestine. These bacteria will adhere to the cell walls | | | | in their best interests to release themselves from the |
| and start to grow in the nutrient-rich environment of | | | | colon as quickly as possible to continue in their quest |
| the small intestine. The brain sends an army of | | | | for survival. |
| anti-bodies to this area to wage a battle with the | | | | Check out the last installment of Bacteria. Friend of |
| invaders. The battle, together with the rapid growth of | | | | Foe? Coming soon. |