Pathogens – their distribution and frequency

Infectious diseases are caused by pathogens. Overall, there are a variety of different pathogens that cause different diseases. Vaccines primarily help against diseases caused by viruses or bacteria.

How viruses and bacteria differ?

So far, there are mainly vaccinations against viruses and bacteria. But what is the difference between the two pathogens?

Actually, the pathogens are not similar at all. Bacteria are larger – and yet are only about one micrometer in size.

In addition, the structure of bacteria is more complex. They have a cell wall and also cell organs. Viruses consist only of hereditary material in an envelope. 1

Ultimately, bacteria can multiply by cell division. Viruses, on the other hand, need a host. Therefore, bacteria also count as living organisms, viruses do not. This is because they cannot breathe, cannot reproduce without a host and also have no metabolism. 2

The diseases caused by some bacteria and viruses can be prevented by vaccination. If one nevertheless falls ill with a bacterial infection, there are often antibiotics which attack the bacteria or prevent their multiplication. Viruses cannot be controlled, but their multiplication can be inhibited by therapy. If one is infected with viruses, then the body’s own immune system must fight the virus alone. 3

Overview: Which diseases are caused by viruses and bacteria?

Vaccinations against these pathogens can prevent serious illnesses. Different pathogens appear in different parts of the world.

Diphtheria

Disease

Diphtheria is one of the diseases caused by bacteria (Corynebacterium diphtheriae) are caused. However, it is not the highly contagious bacteria themselves that are dangerous, but a toxin they produce. This toxin can lead to dangerous complications and consequential damage. Diphtheria is mainly transmitted from person to person by droplet infection. This can lead to infection of the respiratory tract or to inflammation of organs.

Source:
Robert Koch Institute, Diphtheria —- RKI guidebook (last accessed on: 16.12.2020)

Frequency and distribution of the pathogens

Diphtheria bacteria occur worldwide. The disease occurs mainly in autumn and winter. In Germany, diphtheria cases are very rare; in 2017, there were eight cases of disease and no deaths. In Russia or Asian as well as African countries, the numbers were much higher.

Sources:
BZgA, Diphtheria vaccination in children (last accessed on: 16.12.2020)
Robert Koch Institute, Diphtheria —- RKI Guidebook (last accessed on: 16.12.2020)
Robert Koch Institute, Infectious Disease Epidemiological Yearbook of Notifiable Diseases for 2019, pp. 77(last accessed on: 16.12.2020)

Droplet infection

There are some pathogens that are transmitted via so-called droplet infection.

The pathogens are transmitted by droplets of saliva or mucus. When someone talks, coughs or sneezes, the pathogens are released with the droplets. They can then be inhaled by other people via the air.

Pathogens, such as meningo and pneumococcal bacteria, can also be transmitted directly – this happens, for example, when kissing. How they get to the mucous membranes.

Pathogens

TBE (early summer meningoencephalitis) is a disease caused by viruses. The virus belongs to the group of flaviviruses, as do the viruses of dengue or yellow fever. It occurs in different subtypes in Europe and Asia. The main vectors of the virus are ticks, which can transmit the pathogen to humans and animals when they bite. TBE pathogens can also be transmitted to humans through the consumption of raw milk from infected animals. TBE is characterized by flu-like symptoms and can lead to inflammation of the meninges and central nervous system.

Source:
Robert Koch Institute, Epidemiological Bulletin 08/20 (last accessed on: 16.12.2020)

Distribution and frequency

The TBE virus is transmitted by ticks, with about 0.1-5 percent of ticks in TBE risk areas in Germany carrying the virus. The so-called TBE risk areas include large parts of Bavaria, Baden-Wurttemberg, and parts of Hesse, Thuringia, and Saxony. The city district of Dresden has also been designated as a TBE risk area. Individual TBE risk areas are also located in Saarland and Rhineland-Palatinate. Since February 2019, the district of Emsland in Lower Saxony has been the first risk area in northern Germany. A total of 164 counties are officially considered TBE risk areas in 2020.

Source:
Robert Koch Institute, Epidemiological Bulletin 08/20 (last accessed on: 16.12.2020)
Robert Koch Institute, RKI Guide to TBE (last accessed on: 01.03.2021)

Hepatitis

Pathogens

Hepatitis viruses can cause liver inflammation. They can occur in different forms. The classic virus forms are hepatitis A to E. Depending on the form, they appear with different frequency and in different areas in the world. Vaccines are available against the A and B viruses. In Asia there is also a vaccine against hepatitis E, which is not licensed in Europe. Since the hepatitis C virus is constantly and rapidly changing, there is no vaccination against it as yet.

Sources:
Robert Koch Institute, Hepatitis A – RKI Ratgeber (last accessed on: 16.12.2020)
Robert Koch Institute, Hepatitis B and D – RKI Guidebook (last accessed on: 16.12.2020)
Robert Koch Institute, Hepatitis C – RKI Guidebook (last accessed on: 16.12.2020)
Robert Koch Institute, Hepatitis E – RKI Guidebook (last accessed on: 16.12.2020)

Distribution and frequency

Hepatitis, especially hepatitis B, is one of the most common infectious diseases in the world: about two billion people have experienced hepatitis B disease and about five percent of the world’s population suffers from chronic hepatitis. In Germany about 500.000 people are affected by chronic hepatitis and there are about 700 new cases annually.

Sources:
BZgA, Hepatitis B vaccination in children (last accessed on: 16.12.2020)
Children& Jugendarzte im Netz, Hepatitis B (last accessed on: 16.12.2020)

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