Host – Infection, Transmission & Diseases


Parasites specifically look for a host to reproduce. As a rule, the host feeds the parasites, but does not die in the process. Nevertheless, unpleasant symptoms occur that make treatment necessary.

What is a host?

The goal of a parasite or pathogen is to increase its population. The host offers optimal conditions for this, such as sufficient food and protection.

Different types of host exist. The main host is the type that offers the pathogen the best conditions. Accordingly, a parasite strives to reach such a host. The sub-landlord also offers corresponding living conditions. However, these are worse than those of the main host, so that a parasite can develop worse. In the case of a false host, there is no chance of survival. Depending on the parasite, host switching may occur.

The host in which sexual reproduction occurs is called the definitive host. The parasite reproduces asexually in the intermediate host. The transport host transmits the parasite. He himself is not infected. Although the pathogen can develop in the occasional host, it prefers another host, so that the occasional host is rarely infected.

Not only tapeworms and mosquitoes are called parasites . Bacteria , viruses and fungi also multiply in this way and reach other hosts via different routes.

Occurrence, Distribution & Properties

The manner of infecting a host depends on the particular pathogen. Bacteria in particular are often passed on through a smear or droplet infection . In the case of smear infection, infection can also occur when a sick person is not present. Instead, infection occurs via surfaces contaminated with the pathogens. For example, the germs move on when you touch a door handle. Contaminated drinking water can also play a role.

In the context of a direct infection, the germs migrate further via physical contact between people or people and animals – for example by shaking hands.

In the case of a smear infection, the bacteria can be passed on mainly due to a lack of hygiene. Most pathogens are excreted in the stool . Unwashed hands after using the toilet can spread the bacteria.

Droplet infection, on the other hand, takes place via secretion droplets. These come out of the airways and in this way infect people who are nearby. An unprotected cough , sneeze or snort can spread the bacteria in the room.

Tapeworms, on the other hand, enter the gastrointestinal tract through contaminated food . This includes, above all, unwashed fruit and vegetables and undercooked meat. Mosquitoes transmit various parasites, especially in tropical areas. Although humans only serve as an intermediate host in malaria , for example , the infection triggers severe symptoms.

Meaning & Function

A parasite does not usually kill its host. In this way he would deprive himself of his own livelihood. Instead, it uses the organism to reproduce, develop, and spread. Nevertheless, there are health disadvantages for the host. These sometimes become noticeable relatively quickly, while in other cases they remain undetected for a long time. The extent to which the health of the person affected is affected depends largely on the underlying pathogen.

Even in early childhood, people serve as hosts for the various pathogens. These include, for example, bacteria and viruses that cause colds or gastrointestinal problems . A strong immune system can usually banish the invaders on its own within a short period of time. If the body does not succeed in such a procedure, antibiotics or drugs that promote coughing up mucus , for example, can help with a bacterial disease.

On the other hand, other parasites that use the affected person as a host are less harmless. For example, malaria cannot be destroyed by the body’s own defences. The pathogens are transmitted by the bite of an infected mosquito. The parasite then attacks and multiplies in the red blood cells . During typical fever attacks, the blood cells rupture, allowing the parasites to spread and multiply. Left untreated, malaria can lead to death. It is therefore important that a doctor is consulted at the first sign.

Diseases & Ailments

Some of the parasites can cause complications. For example, roundworms cause fever and symptoms resembling asthma as soon as they approach the lungs. Those affected suffer from abdominal pain in the area of ​​the intestine . Sometimes the intestine or bile duct becomes blocked due to the worm infestation . Such a phenomenon results in further complaints, such as colicky abdominal pain, increased gas accumulation and a lack of bowel movements.

Trichinella , on the other hand, are initially noticeable through nausea , vomiting or watery diarrhea . However, they can also spread to the muscles , possibly leading to heart muscle inflammation . The beef and pork tapeworm can get lost in the appendix or the pancreas and cause inflammation here , sometimes with a severe course. By ingesting tapeworm eggs, the pathogens multiply in the intestines, blood vessels and musclesand organs. Cysticercosis may develop . This in turn results in blindness in some patients .

Complications are also possible as part of a bacterial infection that leads to symptoms of a cold. These usually occur more frequently when the disease is not sufficiently cured. Especially in children, the pathogens can migrate into the ear and become noticeable there through a middle ear infection .


Website | + posts

Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.