Germs are microorganisms visible only through a microscope, such as bacteria, fungi, parasites, and viruses. They're commonly associated with infectious diseases, with many people doing everything they can to avoid catching and spreading "germs". However, not all germs represent a cause for concern. The human gut, for example, typically harbors between 300 and 500 different species of bacteria, many of which help people stay healthy.

So, what are some common germs should people look out for and do their best to avoid?

Staphylococcus Aureus

Commonly referred to as "staph", staphylococcus aureus can cause an array of different infections in humans. Most staph infections affect the skin and soft tissues, causing pus-filled abscesses, swelling, and cellulitis. In such cases, symptoms are generally mild, and the infection usually heals within a few weeks. However, staphylococcus aureus can also cause severe infections of the bloodstream (bacteremia) or lungs (pneumonia), both of which produce concerning symptoms such as fever and difficulty breathing.

People who suspect they may have a serious staph infection must seek immediate medical attention.

A leg with the symptom of bacterial cellulitis Tamiko Ihori / Getty Images


Escherichia Coli

Escherichia coli (or E. coli) is a bacterium typically found in animal feces and guts. An E. coli infection can cause severe gastric problems, including abdominal pain, bloody diarrhea, and even kidney failure. In most cases, E. coli is contracted by drinking or swimming in contaminated water, eating undercooked meat, or touching infected animals.

While most cases of E. coli infection are not serious, some people do develop life-threatening complications.

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Salmonella is another bacterium that can cause severe food poisoning symptoms, including bloody stools, diarrhea, nausea, vomiting, chills, and headaches. Most salmonella infections develop after eating undercooked meat or egg products and clear up within a few days.

However, children and adults with weakened immune systems may develop complications requiring medical attention. Similarly, some strains of salmonella can lead to typhoid fever, a potentially deadly disease that usually affects people in developing countries.

Hand selected Egg in egg box Jackyenjoyphotography / Getty Images


Streptococcus pneumoniae

Streptococcus pneumoniae bacteria can cause a variety of infections ranging from mild to severe. Non-invasive pneumococcal infections, such as otitis media (ear infection), sinusitis, and bronchitis, usually cause mild symptoms and often clear up on their own.

However, streptococcus pneumonia can also cause life-threatening infections, including septicemia (blood poisoning), osteomyelitis (bone infection), pneumonia, and meningitis. These conditions represent medical emergencies requiring treatment with antibiotics.

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Influenza viruses circulate throughout the world, causing seasonal epidemics and, in very rare cases, novel pandemics such as H1N1 (swine flu). The seasonal flu is rarely dangerous, although it can cause a range of unpleasant symptoms, including headaches, fever, coughs, joint pain, severe malaise, and a sore throat. Most people with flu get better after a couple of weeks.

Some groups are at higher risk of developing complications, including pregnant women, young children, the elderly, and people with immunosuppressive or cardiopulmonary conditions.

Caucasian young woman coughing and sitting under the duvet at home gpointstudio / Getty Images



Norovirus is a highly contagious virus that causes an illness some people refer to as "stomach flu". Common symptoms of norovirus infection include vomiting, diarrhea, stomach cramps, and nausea. While norovirus infections typically get better within a few days, people who contract them need to drink plenty of water to prevent dehydration and stay home for at least two days after symptoms end.

People can still spread norovirus for a few days after they feel better, making it one of the most contagious germs around. Fortunately, it is possible to prevent infection through frequent hand washing and rinsing fruits and vegetables prior to consumption.

woman with stomach pain Domepitipat / Getty Images



Campylobacter is the most common bacterial cause of diarrhea in the U.S. The germ spreads via the consumption of contaminated food and drink, with poultry products representing an especially significant risk. Most people quickly recover from campylobacter infections without the need for antibiotics. However, older people and those with weakened immune symptoms may require treatment to prevent complications.

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Rotavirus is a highly contagious virus that usually affects babies and younger children. While rotavirus can cause distressing symptoms such as abdominal pain and vomiting, the vast majority of children recover within a week. If complications arise, they are usually related to dehydration. As such, keeping children hydrated is a crucial part of the recovery process. Most children are vaccinated against rotavirus as babies, so the germ very rarely presents cause for concern.

child with stomach ache Liderina / Getty Images


Human Metapneumovirus

Human metapneumovirus (hMPV) causes respiratory infections and is very common, affecting most children by the time they are five years old. Symptoms of hMPV infection include a runny nose, cough, headache, and fever.

Occasionally, children develop pneumonia from hMPV, and the virus can also worsen asthma symptoms. For the most part, however, hMPV is less serious than other respiratory infections, such as influenza.

Man using inhaler SCIENCE PHOTO LIBRARY / Getty Images


Cold Viruses

A number of germs can cause the common cold, including rhinovirus and respiratory syncytial virus (RSV). Although highly contagious, colds very rarely cause serious symptoms and can be dealt with at home. No antiviral medications exist to treat the common cold, so remedies must treat the symptoms directly.

Decongestants can alleviate congested sinuses, for example, while pain relievers can treat sore throats and headaches.

 Ill Woman with Cold dragana991 / Getty Images


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