Bacterial Diseases
Salmonella
Salmonella is a type of bacteria usually found within poultry eggs, unprocessed milk, meat and water. It is a rod-shaped gram-negative enterobacteria that causes typhoid fever. It was discovered by an American scientist named Dr. Daniel Salmon.
It can cause:
- Diarrhoea, constipation
- Headaches
- Stomach cramps
- Nausea and vomiting
- Fever
- Possibility of blood in faeces
Every year approximately 40,000 cases of salmonella are reported. It can be avoided by thoroughly cooking food to the boil. It can also be transported by turtles and birds. There is a very high chance of dehydration with the disease, not directly but from the diarrhoea, vomiting and loss of salts.
After being eaten the salmonella bacteria passes through the stomach and into the intestines where it binds to the wall of the intestine. Through some special proteins that it makes in response to the particular conditions in the intestine, it actually penetrates the barrier between us and the outside. Once it has gained access to our insides it is taken to our liver or spleen. Most other bacteria would be killed along this journey but salmonella has evolved such a mechanism to prevent our immune system from doing its job effectively. In the liver, it then grows and spreads.
Cholera
Cholera is a widespread, bacteria-caused, disease which is spread by unclean water. It is specifically caused by the bacterium vibrio cholerae which is a gram-negative bacteria. It is transmitted via unclean water but it doesn’t multiply in the water itself. Certain blood types within people are better at dealing with vibrio cholerae, blood type AB is the most resistant whereas blood type 0 is the most susceptible.
Effects:
- Diarrhoea
- Headaches
- vomiting
Treatment:
- Rehydration therapy
- Inputs of salts and glucose back into the body
Preventative:
- Clean drinking, washing and cooking water
- Safe disposal of sewage
- Hygienic preparation of food
Protoctistan Diseases
Malaria
Malaria is one of the most destructive diseases to humans. It is caused by a parasite called Plasmodium, of which there are two types, Plasmodium falciparum and Plasmodium vivax. The life cycle of Plasmodium is shown below.
The life cycle of Plasmodium has to take part between a female anopheles mosquito and a human. The effects of Plasmodium within a human can be seen in two stages, bursting out of the liver cells and releasing toxins is the first stage and a major fever results. The second stage is when they burst out of the red blood cells also releasing toxins and producing a fever.
Malaria can be combated by:
- Preventing the mosquito from biting humans with nets, protective clothing and insect repellents.
- Killing the mosquitoes by using insecticides like DDT, spraying or draining the breeding grounds and biological control e.g. fish.
- Attack the parasite with drugs (quinine) and vaccines.
Read more about the Immune System
Viral Diseases
Influenza
Influenza is an endemic disease caused by a virus consisting of a central strand of RNA coated in protein. It affects the upper respiratory system causing sore throat, cough and inflammation of the sinuses.
It is transmitted by droplet infection, i.e. with sneezing or via tissues. It would be prevented by quarantine but is very difficult to control. Vaccines are available but due to the number of different types of the virus, they are not always effective.
Table Showing all four diseases
| Organism that Causes Disease | Tissue Affected | Source of Infection | Mode of Transmission | Prevention and Control Methods | |
|---|---|---|---|---|---|
| Salmonella | Prevent mosquitoes from biting humans, eliminate the mosquito or attack parasite | Digestive system – toxins released causing diarrhoea | Bacteria on Food | Not thoroughly heating food and being unhygienic | Better hygiene when cooking |
| Cholera | Bacteria – gram negative | Digestive system – toxins released causing diarrhoea + vomiting | Faeces infected water | Consuming unclean water | Provide clean water for drinking, washing and cooking |
| Influenza | Virus | Upper Respiratory System | Exhaling – Droplet infection | Inhaling – Droplet infection | Prevent Contamination + Vaccines |
| Malaria | Parasite | Liver + Red Blood Cells (fever in two stages) | Female Anopheles mosquito | Mosquito biting human | Prevent mosquitoes from biting human, eliminate the mosquito or attack parasite |
Frequently Asked Questions
What are bacterial diseases?
A state of illness caused by some bacteria is called a bacterial disease. The signs and symptoms of these diseases are either caused by toxins produced by bacteria or the harm to the cells caused by bacteria.
What are 5 disease-causing bacteria?
The 5 disease-causing bacteria include Salmonella typhi, Vibrio cholera, Streptococcus pneumonia, Clostridium tetani, and Clostridium difficile.
Which organism causes malaria?
Malaria is a disease caused by a group of protozoa known as Plasmodia. The common protozoa include Plasmodium falciparum and Plasmodium vivax. This parasite is transmitted to humans via a female Anopheles mosquito which acts as a vector.
What do you know about influenza?
Influenza is a viral disease of the upper respiratory tract caused by the influenza virus. It spreads from one person to another via respiratory droplets. Vaccines are available to prevent this disease.