The food people eat can give them strength and nutrients. However, if there is not enough food, the human body will not receive enough nutrients and strength to fight viruses and bacteria that enter the body. Additionally, the quality of the food also plays an important role in terms of nutrients and strength. If the quality of food is impure or rotten, it can harm the body. Water in third world countries is scarce; The sources of water that Ugandans get are from rivers, lakes and ponds. In these bodies of water there are bacteria that can harm the body and make people sick. When the body is attacked by bacteria and viruses, it eventually fights them off. However, when the body cannot fight bacteria or viruses, the situation becomes worse and can eventually lead to death. To fight these viruses, the body needs your body's cells to fight the bacteria or viruses, but if the DNA or genes are not strong enough to fight them. As time passes and people slowly die from bacteria and viruses, the population will decline and, long enough, cause the entire population to die.