Education: contagious diseases
What are pathogens and how do they work? Learn more about them and how they spread diseases
WHEN a disease is passed on from one living being to another, it’s called a contagious disease. These diseases are caused by pathogens, which is the scientific name for germs – tiny organisms (living things) that enter your body and make you sick.
There are many kinds of pathogens including bacteria (which cause illnesses such as tuberculosis and cholera), viruses (which cause flu, colds, measles and yellow fever for example), parasites (which cause malaria for instance) and fungi (which cause illnesses such as fungal meningitis).
HOW DO YOU BECOME INFECTED?
There are several ways in which you can contract a contagious disease. S Insect bites Certain insects carry pathogens that they transfer to humans. For example, certain mosquitoes are carriers of malaria and can transfer this disease to humans by biting them. S Food/water contamination When food isn’t properly cooked or waste material is present in drinking water, people can contract diseases such as cholera and salmonella. S Direct contact A disease can be transferred from one person to another when they come into contact with each other, by shaking hands for example. When someone sneezes, their germs are spread into the air and can infect people nearby. Diseases such as flu, colds and chicken pox can be transmitted in this way. S Indirect contact Many of the diseases that can be transferred by direct contact can also be passed on by indirect contact, because germs can live outside the human body for a while. For example if an infected person touches a door handle and later another person touches the same handle, their germs can infect that person. This is why it’s a good idea to wash your hands with soap and water often, especially if you’re sick. Germs can also move around in the air in little droplets after someone carrying the disease has coughed.
IMMUNE SYSTEMS
When bacteria or viruses enter your body, it starts to multiply and that’s when you become sick. Your body has a built-in defence against germs called the immune system. Your immune system involves many body parts including organs, cells and tissue working together.
When your immune system becomes aware that there are dangerous bacteria or viruses in your body, it reacts by sending messages to these other parts of your body so they can start making special proteins to remove the invaders. These proteins are called antibodies. Specific antibodies fight specific diseases, and they’re designed to destroy only dangerous cells.
Your immune system won’t always stop you from getting sick – everyone gets sick sometimes – but it does help you to get better. Your immune system is also clever: if it fights a certain kind of germ once, it remembers that germ and how to rid the body of it. That’s why older people often have more resistance to illnesses than babies and children – their immune system is more experienced at fighting many kinds of germs.
When you’re not getting enough sleep,
feel stressed or tired and aren’t eating healthily, your immune system is weakened – which means it doesn’t work properly. And when that happens you’re more vulnerable to catching contagious diseases such as colds and flu.
VACCINATIONS
We’re also immunised against certain diseases with vaccinations. This is when you’re injected with a virus that isn’t effective anymore, so it can’t make you sick – but your immune system doesn’t know this and creates antibodies to fight the disease. So if you catch the real disease your body is able to recognise the germ and protect you against it. Examples of diseases we’re vaccinated against are German measles and mumps. Thanks to vaccinations against smallpox, a deadly disease that has killed many people through the centuries, it was completely eradicated.
TUBERCULOSIS (TB)
This illness is easily transferred from one person to another, because when a TB sufferer coughs or sneezes the bacteria are spread into the air.
TB is one of the top 10 causes of death worldwide. In 2015, 10,4 million people were diagnosed with TB and 1,8 million died as a result of the disease. South Africa is one of the six countries in which 60 percent of the world’s TB sufferers are found (the others are India, Indonesia, China, Nigeria and Pakistan).
TB’s symptoms include feeling weak,
Strengthen your immune system by getting enough sleep and eating healthily
loss of appetite, weight loss and fever. When TB spreads to the lungs the patient has coughing fits and coughs up phlegm or even blood. TB of the lungs is the most common kind but it can also affect other parts of the body.
The TB germ can live in your body without you knowing about it, because your immune system can fight it and keep you healthy. But when the immune system becomes too weak to fight the germ, you’ll get active TB. This is why people who are HIV-positive often die of TB – the HI virus makes their bodies so weak that their immune system can’t fight the TB germ. About 35 percent of Aids-related deaths are as a result of TB.
TB can be cured, but the patient needs to stay on their medication for a long time – it can sometimes take up to nine months for all the germs to be killed. If a TB patient stops taking their medication too soon, the germs can adapt and become even stronger – and then stronger medication is needed to kill the bacteria.