top of page

It's all about germs - Giardiasis

Updated: Apr 2

We are surrounded by an incredible number of germs every day and they are also very active in our bodies. We also need them there so that our organism "runs smoothly". But there are germs that can harm us - we get sick. Most of the time, our body can defend itself quite well against infections thanks to the immune system, but as the saying goes: "Prevention is better than cure!"

Illustration of giardia intestinalis
Giardia Intestinalis

With this article we want to give a little insight into the world and diversity of germs - bacteria, fungi, viruses. What is it that crawls and flies on surfaces or infects us through the air? How can we become infected and how long do these beasts survive?


Name: Giardia Intestinalis

Species: Parasite


Symptoms: The cyst-producing, single-celled parasite produces the diarrhoeal disease Giardiasis, which shows its first symptoms after one to three weeks. Recurrent diarrhoea, flatulence, fatigue, nausea, dehydration or weight loss are among them. It usually affects young children or, in adults, mostly men between 30 and 59 years of age.


Mode of transmission: The parasite, which is still infectious weeks after excretion, is transmitted orally-faecally through direct contact with fellow humans, contaminated surfaces or ingestion of food and drinking water. Giardiasis is also called travel sickness, as it often occurs after stays abroad and is due to poor hygiene conditions.


Survival: Weeks to months after shedding


Name: Mumps

Type: Virus

Symptoms: Early symptoms, such as fever, headache, malaise, muscle aches and loss of appetite can herald mumps disease. If the infection has really broken out, it causes an inflammatory and painful swelling of the parotid gland, sometimes affecting only one ear, but in most cases both ears. In rare cases, temporary deafness can also be the result.


Transmission route: Mumps viruses are mainly transmitted through the air by droplet infection. Direct saliva contact, for example when kissing, can transmit the virus and also, although very rarely, through contact with objects contaminated with saliva.


Survival: Only a few hours outside the human body.


Illustration of Epstein-Barr virus
Epstein-Barr Virus

Name: Epstein-Barr Virus

Type: Virus

Symptoms: Epstein-Barr virus (EBV) is the most common trigger of glandular fever (infectious mononucleosis) and is typically accompanied by fever, fatigue, sore throat and swollen lymph nodes, but is usually harmless and usually heals quickly. Since the symptoms are similar to a cold or flu, the infection usually goes undetected. However, it is also suspected of promoting both cancer and autoimmune diseases such as multiple sclerosis (MS).

Transmission route: More than 90 percent of people carry the virus and it is usually transmitted through saliva contact when kissing or by using the same glass, cutlery or toothbrush. But EBV can also spread through blood transfusions or sexual contact. In most cases, infection occurs in childhood and runs its course without any noticeable symptoms. However, the virus remains in the body forever and can also become infectious again after reactivation.

Survival: Outside the human body, the virus does not survive for long, but on surfaces as long as they are moist.


Illustration of a Rubella Virus

Name: Rubella

Type: Virus

Symptoms: Rubella infection is usually accompanied by mild symptoms such as headache, increased body temperature, conjunctivitis and inflammation of the mucous membranes of the upper respiratory tract. What is clearly visible, however, is the rash, which spreads from the face over the body and disappears after one to three days. Children often only have the rash, while the other symptoms are more severe in adults.    

The infection can have serious consequences for unborn babies in the womb during the first three months. Possible damage includes defects to the heart, eyes and ears. In addition, an infection in the first four months of pregnancy can also lead to a miscarriage or premature birth.


Transmission route: Rubella viruses are transmitted through the air (aerogenically) by droplet infection. The virus can also be transmitted to the unborn child via the placenta in the womb and have considerable consequences.


Illustration of dengue virus
Dengue Virus

Name: Dengue virus

Type: Virus Symptoms: There are different courses, ranging from mild flu-like symptoms such as fever, headache and aching limbs to life-threatening conditions such as shortness of breath, circulatory collapse or vomiting blood. Depending on the degree of the disease, fever is often accompanied by severe exhaustion, chills and gastrointestinal bleeding, and occasionally conjunctivitis. Skin rashes, swelling of the lymph nodes and spleen, joint and muscle pain are other possible symptoms. If the fever drops, however, this is not yet an improvement, because it usually rises again and comes back with a large skin rash. If the course is mild, the infection may already have subsided after a few days, but it usually takes several weeks for sufferers to recover. Transmission route: The dengue virus is one of the viruses transmitted by mosquitoes, sand flies or ticks. There are different stereotypes that occur in more than 100 tropical and subtropical regions, including the Canary Islands. One of the most important vectors of the pathogen is the yellow fever mosquito Aedes aegypti. Survival: The virus remains active in mosquitoes for life and is even passed on to offspring.


Illustration of lyme disease
Lyme Disease

Name: Lyme disease / Lyme borreliosis

Species: Bacterium

Symptoms: Most infections run their course without specific symptoms. However, if symptoms do occur, they can be very different, so that a diagnosis is quite difficult. The so-called wandering redness is one of the first signs in about 90 percent of those affected. A ring-shaped reddening of the skin forms around the sting site, which enlarges outwards over a period of days, but it can also occur on other parts of the body. Fever, swelling of the lymph nodes, muscle and joint pain are also common symptoms. However, skin changes up to bluish discolouration are rather rare.

In three out of 100 people affected, however, the Borrelia bacteria can also affect the nervous system, and this can take weeks or months. Neuroborreliosis can lead to various symptoms of paralysis, nerve pain and, in children, also to a non-suppurative meningitis. Joint inflammation (Lyme arthritis) can occur in about five out of every 100 people who contract the disease.

Transmission route: The Borrelia bacteria are not transmitted through the air or surfaces, but through the bite of a parasite, the common wood tick or better known as a tick. About one third of ticks in Germany are infected with Borrelia, but not every bite is contagious. But the longer the tick is on the body and sucking blood, the higher the risk of infection. Lyme disease cannot be transmitted from person to person.


Illustration of Variceller-Zoster Virus
Varicella-Zoster Virus

Name: Varicella-Zoster Virus

Type: Virus Symptoms: Varicella zoster viruses belong to the Herpesviridae family and can cause varicella (chickenpox) on the one hand and herpes zoster (shingles) on the other. The main characteristic of varicella are initial skin lesions which develop into blisters that spread from the face to the trunk and then the entire body. High fever and an itchy skin rash are the unpleasant accompanying symptoms. Herpes zoster also manifests itself with blisters, an itchy rash and a slight fever, but a burning pain in the spinal and cranial nerve ganglia is the most unpleasant and long-lasting symptom. Transmission route: The name chickenpox comes from the theory that the marks on the skin resemble the pecks of a chicken but the viruses which cause the blisters are very easily transmitted via the air (coughing, exhaling). Also smear infections via saliva, blister contents or tear fluid are possible. Herpes zoster is usually caused by viruses still present in the body, which survive for years after a varicella infection has been overcome and can cause a second infection if the immune system is weakened. Survival: The viruses can survive on surfaces for 4.5 hours and up to 8 weeks.


Name: Adeno virus

Species: Virus Symptoms: Adenoviruses can cause a variety of diseases, such as respiratory, gastrointestinal, or ocular conjunctiva and cornea. In most cases, the eyes are affected. Infection begins with redness of the eyes and swelling of the conjunctiva. Itching, tearing, and clouding of the cornea also usually occur. After 2 to 4 weeks, the symptoms usually subside. Mode of transmission: The hands are the most common route of transmission, as infected persons quickly have the viruses on their hands and can then pass them on via all surfaces they touch. Shaking hands should also be avoided when infected, as the viruses can also be transmitted this way. Survival: The disease usually breaks out 5 to 12 days after infection. The risk of transmission begins with the first signs of illness and usually lasts for at least 2 weeks. At room temperature, the pathogens may adhere to surfaces for several weeks and remain contagious there.


Illustration of Polio Virus
Polio Virus

Name: Polio virus

Species: Virus Symptoms: Poliomyelitis, also called polio, is caused by the poliovirus. Most people do not notice the infection at all because they do not develop any symptoms. However, since there are three variants, one is not automatically immune after contracting the disease. In the case of abortive poliomyelitis, symptoms such as fever, sore throat, headache or muscle aches, inflammation of the stomach or nausea may occur, but they go away after a few days. In the other two variants, the central nervous system (CNS) is also affected. If fever, neck stiffness, back pain and muscle spasms occur as signs of meningitis, everything points to non-paralytic poliomyelitis. If there is also uneven paralysis in the leg, arm, abdominal, chest or eye muscles, this is called paralytic poliomyelitis. In severe cases, the diaphragm, which is responsible for breathing, may also be affected and the patient could die.

Even though the virus has been virtually eradicated in our latitudes, it can be brought in from other countries. Only vaccination offers comprehensive protection against all variants.

Transmission route: The polio virus enters the body through the mouth or nose, as a smear or droplet infection. The virus can pass from a surface to one's own hand and then enter through the mouth, e.g. by ingesting food. The virus can also be passed on through contaminated food itself or by shaking hands. Transmission is also possible through the smallest droplets when speaking or breathing. From the oral cavity, the pathogen first reaches the intestine, from where it can migrate into the lymphatic and blood vessels and spread throughout the body via these.

Survival: The virus can be passed on as long as it is excreted in the stool. This can be up to six weeks.


Illustration of Monkeypox

Name: Monkeypox virus Orthopoxvirus simiae

Species: Virus Symptoms: Initial symptoms of the disease include fever, headache, muscle and back pain, and swollen lymph nodes. A few days after the onset of fever, skin lesions develop, which simultaneously progress through the stages from spot to pustule, ultimately crusting and falling off. The rash is usually concentrated on the face, palms, and soles. The skin and mucous membrane lesions can also be found on the mouth, genitals, and eyes. Symptoms usually last between two and four weeks and disappear on their own without treatment. Complications in endemic countries include encephalitis, bacterial skin infections, fluid loss, conjunctivitis, corneal infections, and pneumonia. Transmission route: Human-to-human transmission is rare and only possible with close contact, but can occur through contact with body fluids, the typical skin lesions (e.g., vesicle contents, scabs) of monkeypox infected individuals. It is currently uncertain whether monkeypox can be spread through direct sexual routes of transmission (e.g., semen or vaginal secretions), but direct skin contact with lesions during sexual activity can spread the virus. Particularly high concentrations of virus are found in the typical smallpox lesions (skin lesions). Transmission is possible even when still nonspecific symptoms (such as fever, headache, and pain in the limbs) appear even before the skin lesions appear during face-to-face contact through excreted respiratory secretions. Others can also become infected through clothing, bedding, towels, or items such as eating utensils that have been contaminated with the virus through contact with an infected person. Ulcers, lesions or sores in the mouth can also be contagious, meaning the virus can then be transmitted through the saliva of such infected individuals. The entry sites are often the smallest skin lesions as well as all mucous membranes (eye, mouth, nose, genitals, anus) and possibly the respiratory tract. Infected persons are contagious as long as they have symptoms (usually for two to four weeks).

Survival: Monkeypox viruses can survive and be infectious for long periods of time (days to months) on surfaces (e.g., glasses, silverware, bedside tables) or fabrics (e.g., bedding or towels).


Illustration of Measles

Name: Measles

Type: Virus Symptoms: A measles infection usually starts like a flu with a cold, cough, fever and inflammation of the nose, throat or conjunctiva. Typical of measles is a rash with white to blue-white spots on the mucous membrane of the mouth and the pinkish-brownish spots on the skin of the body that appear after three to seven days and persist for up to a week. The most persistent symptom, however, is an immune deficiency that lasts up to six weeks and can promote further illnesses. Transmission route: The measles viruses are transmitted from person to person and via surfaces. Particularly tricky, the highly contagious viruses can also be passed on over several metres by droplet infection. For this reason, there is also a reporting obligation and infected persons should also be isolated if possible. Survival: 2 hours in the air


Illustration of herpes simplex virus
Herpes simplex virus

Name: Herpes simplex virus

Species: Bacterium

Symptoms: The most common forms of the enveloped virus are herpes labialis (lip herpes), and herpes genitalis (genital herpes). In the most common variant, herpes labialis, it usually starts with a slight tingling sensation. Those affected know the unpleasant feeling and immediately know what to do - get the right cream or patches at the pharmacy. Within a very short time, sore, sensitive areas with small blisters appear around the mouth. The blisters fill with clear liquid and burst after a few days. What remains is a small wound that quickly crusts over and heals after 8 to 14 days. Affected persons often feel ill and exhausted. Genital herpes is also manifested by fluid-filled blisters, which, however, occur in the genital area. In this disease, too, they burst after 1-2 days and then heal. Other symptoms may include pain in the genital area, headaches, aching limbs and fever. These symptoms also subside within a few days. Transmission route: Transmission of both variants occurs via smear infection through saliva or genital secretions, mucous membranes, or simple skin contact. Survival: 4.5 hours to 8 weeks


Illustration of pseudomonas aeruginosa
Pseudomonas aeruginosa

Name: Pseudomonas aeruginosa

Species: Bacterium

Symptoms: The tricky thing about the bacteria is that most strains have developed a resistance to antibiotics. Thus, pneumonia, wound or urinary tract infections or, in the worst case, sepsis (blood poisoning), which can be caused by the bacteria, are now very difficult to treat. Those with previous illnesses, such as cystic fibrosis patients, hospital patients, the elderly or infants are particularly at risk. Transmission route: The pathogens often enter the body via tiny droplets in the air (so-called aerosols). By coughing or sneezing, the bacteria can "fly" several metres and then be inhaled by another person. Researchers have shown that the tiny particles can remain suspended in the air for more than 45 minutes. However, pseudomonads are also ingested with food or spread through direct contact via hands and objects. Careful hand hygiene is therefore very important. Survival: 6 hours to 16 months; on dry floors: 5 weeks


Illustration of Listeria

Name: Listeria

Species: Bacterium

Symptoms: If the immune system is intact, the course of the disease remains asymptomatic in most people. A mild feeling of illness and fever may occasionally occur. People with a weakened immune system may develop severe flu-like conditions. Listeria can have serious consequences on unborn and newborn babies. Premature births and stillbirths can occur, or neonatal listeriosis, which is associated with severe and often fatal meningitis.

Transmission route: The bacteria are found in the environment and in agricultural areas, but food can also be contaminated through processing. Transmission occurs through consumption of these foods, but can also occur faecal-orally through healthy excretors or through direct contact with infected humans, animals or soil.

Survival: 1 day to several months on surfaces


Illustration of Legionella

Name: Legionella

Species: Bacterium

Symptoms: Legionella cause various disease patterns in humans, ranging from flu-like symptoms, called Pontiac fever, to severe pneumonia, known as Legionnaires' disease.

Transmission route: Legionella are environmental germs that are widespread worldwide and are a natural component of surface water and groundwater in small numbers. Legionella proliferate best at temperatures between 25 °C and 45 °C. Above 60 °C they are usually killed and below 20 °C they hardly reproduce. Especially in artificial water systems such as water pipes in buildings, the pathogens find good growth conditions at corresponding temperatures. Legionella can multiply particularly well in deposits and coatings in the pipe system.

The pathogens are transmitted through atomised, nebulised water. The droplets containing the pathogen can spread in the air and be inhaled. Possible sources of infection are, for example, showers, whirlpools, humidifiers or water taps, as well as cooling towers. Infection from person to person does not occur.


Illustration of staphylococcus areus
Staphylococcus aureus

Name: Staphylococcus aureus (incl. MRSA, VRSA)

Species: Bacterium

Symptoms: This bacterium, which is widespread worldwide, belongs to the staphylococci species. It colonises the skin and mucous membranes in the nasopharynx - but usually without causing any symptoms. However, if the germs enter the body, e.g. through wounds, they can cause boils, abscesses, meningitis, wound infections but also pneumonia or sepsis. The tricky thing is that the strains of MRSA and VRSA, which are now known as "hospital germs", are resistant to most common antibiotics and are therefore very difficult to fight in the body.

Transmission route: The bacteria are most often transmitted from person to person via the hands, but only cause an infection in the body, e.g. in wounds. Therefore, you can also infect yourself if you touch a wound with contaminated hands. In addition the pathogen can also be transmitted via objects and medical instruments, or via contact with farm animals carrying the bacterium.

Survival: 7 days to 7 months


Illustration of Streptococcus

Name: Streptococcus

Species: Bacterium

Symptoms: The most common bacterium, S. pyogenes can cause many different illnesses, including local purulent infections of the skin or throat, such as middle ear, sinus, pharyngitis or tonsillitis but also scarlet fever. If an infection is not treated, it can lead to further illnesses such as rheumatic fever, neurological abnormalities or even movement disorders.

Transmission route: Smear and droplet infection, direct contact or via surfaces.

Survival: 3 days to 6.5 months


Illustration candida albicans
Candida albicans

Name: Candida albicans

Type: Yeast fungus

Symptoms: The yeast fungus normally permanently colonises mucous membranes in the mouth and intestines as well as the skin. In healthy people, however, the immune system has the fungus well under control. With a weakened immune system, skin infections occur, but infestation of the internal organs or sepsis are also possible consequences.

Transmission: Through direct or indirect contact with infected skin or surfaces.

Survival: 1 day to 4 months


Illustration Influenza

Name: Influenza

Type: Virus

Symptoms: Typical symptoms are a sudden feeling of illness, fever, sore throat and dry cough, accompanied by muscle, limb, back or head pain. If the infection is uncomplicated, it usually subsides after five to seven days. However, it can also take a severe course, leading to death in the worst case. The most common complications are pneumonia and middle ear infections in children.

Transmission: Infection with the influenza virus usually occurs via droplet infection from person to person or from surfaces to person. By coughing, sneezing, even talking, others in the environment can catch it from infected people.

Survival: 1 to 2 days


Illustration of Escherichia Coli
Escherichia coli - E.Coli

Name: Escherichia coli (E. coli)

Type: Bacterium

Symptoms: There are "harmless" E. coli bacteria that are part of the normal human intestinal flora. The harmful variants can cause urinary tract infections, severe diarrhoea, wound and respiratory infections and blood poisoning. The bacteria are also the most frequent causes of infections after operations, so-called nosocomial infections.

Transmission: Transmission occurs through the ingestion of minute traces of faeces via direct or indirect contact with contaminated persons, animals or objects. Inadequately heated food or contaminated water, even when bathing, can also cause infections. The incubation period is three to five days.

Survival: 1.5 hours to 16 months


Illustration Salmonella

Name: Salmonella

Type: Bacterium

Symptoms: Typical food poisoning with severe diarrhoea

Transmission: Transmission occurs through direct contact with infected persons or indirectly through contaminated food or via surfaces. Classic examples of sources of infection are insufficiently heated eggs or poultry, raw meat or ice cream. However, the bacteria can also get into the food via contaminated kitchen equimpent (e.g. cutting boards).

Survival: 1 day up to 4 years


Illustration of Corona Virus - Covid 19 - SARS-CoV-2
Corona Virus - Covid 19 - SARS-CoV-2

Name: Corona (COVID-19; SARS-CoV-2)

Type: Virus

Symptoms: Mild cold symptoms with cough, fever, cold, loss of smell and taste, up to severe pneumonia with lung failure, but sometimes no symptoms at all despite infection.

Transmission: High risk of infection through droplet infection or aerosols produced when breathing, coughing, speaking, singing and sneezing, as well as through surfaces.

Survival: up to 28 days


To be continued...




Published: 4. February 2021 (Last update: 4. October 2022)


bottom of page