How microbes affect our health

Microorganisms (microbes) are ubiquitous in nature, present in water, soil, and air and on the surface and interior of all animals. Bacteria play key roles in our global ecosystem, recycling nutrients, including Nitrogen and Carbon, for use by plants and animals. Microbes also carry out essential roles in normal healthy humans, animals, and plants, including ensuring nutrient availability, promoting health, and preventing disease. A very small number of microbes have the potential to cause disease, which can have a major impact on the health of humans, animals, and agriculture. It is, therefore, very important that we understand how microbes promote health and how they cause disease so we can develop ways to ensure their positive impact and reduce or prevent their harmful effects.

Do microbes make you sick?

Yes, some microbes can make you sick. Microbes are tiny living things like bacteria and viruses. While most microbes are harmless or even helpful, some can cause illnesses. For example, the flu virus can make you feel very tired and achy, and certain bacteria can give you a stomach upset. These harmful microbes can spread through coughs, sneezes, dirty hands, and contaminated food or water. Washing your hands, cooking, and storing food correctly, and not getting too close to people who are ill can help protect you from getting sick from these microbes. For some very nasty diseases, we can also be vaccinated to train our bodies to prevent them from making us ill.

Which microbes have caused the most serious illnesses and why?

Some microbes have caused very serious illnesses in people, animals, or plants. For example, a bacterium called Yersinia pestis caused the Black Death, a plague that killed millions in the 1300s. I asked a colleague called Prof Wendy Barclay from University College London what she thought was the most dangerous microbe, and she said the virus that causes measles. Measles is dangerous because it spreads very easily and can make people very sick. It starts with a fever, cough, runny nose, and red eyes, then causes a rash all over the body. Measles can lead to serious problems like pneumonia (a lung infection), brain swelling, and even death. It is especially risky for young children and people with weak immune systems. Even though there is a vaccine that prevents measles, outbreaks can still happen if people are not vaccinated. Getting vaccinated is important to keep everyone safe from this serious disease.

Can you have two diseases at the same time?

Yes, it’s possible to have more than one disease at the same time. Sometimes, if someone’s immune system isn’t working as well as it should, and they are unable fight off infection they can be infected by multiple types of microbes that at once. Also, if you pick up an infection it can make you more vulnerable to picking up another as your immune system fights off the original microbe. For example, patients infected with flu (caused by a virus) often have symptoms that affect their lungs which in turn makes them vulnerable to their lungs being infected by bacteria. When this happens, your body must fight both infections, which can make you feel worse. Doctors can help by giving the right treatments for each disease.

Can mould grow in your body?

Mould is a type of fungus that normally grows on things like food or damp surfaces, but not usually in our bodies. As the mould fungi grows it forms multicellular filaments called hyphae that knit together to form a network called a mycelium, which is visible to the naked eye as fuzzy or slimy patches in various colours like black, green, white, or orange. Moulds like damp, warm, and humid environments to grow, making them common on things like old food or damp walls. However, if someone has a weak immune system, certain types of mould can manage to grow in the lungs and cause respiratory infections. However, for most healthy people our immune systems are strong enough to fight off mould and stop it growing in our bodies.