How do we know we are suffering from a disease?
Our body is made up of specific organs and tissues. Each of them performs a particular function. When we suffer from a disease, some of these organs do not function efficiently. These changes give rise to symptoms and signs of disease.
At times, the body also shows some changes in its appearance like the skin may develop lumps or a change in colour. That’s precisely when we realise that our body is suffering from some disease.
What is a Symptom?
We can define a symptom as any feeling of illness or physical or mental change that is caused by a particular disease.
Let us understand this by taking an example:
When we have a headache, we feel uneasy and restless. This indicates that we are suffering from some disease. Yet they do not tell us which particular disease it could be. So symptoms are ‘indefinite and general’ indicators of a particular disease.
What are the signs of disease?
Signs of disease are what a doctor will look for on the basis of the symptoms. Let us try understanding this with the help of a situation.
When we visit a doctor based on the symptoms, the doctor looks out for specific signs. To get a clear idea, he may ask us to do laboratory tests of blood and urine. The results will then point
out the specific disease we may be suffering from. Once these tests are done, and the signs are identified only then we know the disease.
Hence, signs are ‘definite’ indicators of a particular disease.
What is the cause of a disease?
Diseases may not be caused by one single reason. There may be several contributory reasons for a person to fall ill. The immediate cause is the attack of microbes but their attack will be successful only when the body is not immune to it.
To understand this let us take an example:
We have a person who is suffering from malaria. The blood tests show the presence of the malarial parasite. We know that malaria is caused by the bite of the female Anopheles mosquito. That means the area in which this man lived has many mosquitoes. But not everyone living in that area suffers from Malaria. One of the reasons for the same could be that the mosquitoes did not bite other people. But it could also be that the others have a stronger immune system. The immune system is a network of biological processes that protects an organism against diseases. So it could happen that the man who suffered from Malaria may not be immune enough to fight off the disease. This could be because the man is financially poor and hence, does not eat healthy food. Therefore, he is undernourished.
Here, mosquito bite was the immediate cause of the disease. But the other reason was the lack of nourishment due to poverty.