The human body can serve as an excellent home for many organisms, most of which are completely harmless. However, some of them can be dangerous. Infection with some parasites can lead to death.
Infection of the body
The smallest organisms that can cause disease are viruses that are visible only under an electron microscope. They are able to reproduce exclusively within the cells of the body. Then follows bacteria and yeast fungi - fairly large unicellular organisms, visible through an optical microscope. The largest "invaders" of our body are called parasites. This term unites the most diverse organisms: from plasmodia (the simplest, which can be seen only under a microscope) to worms, leeches, mites and lice, which are complex multicellular organisms visible to the naked eye. Several hundreds of species of parasites can live on the human body or inside it. Most of them are harmless and do not deserve attention. A significant part of them lives on the skin and hair or in the intestines.
Identification of parasites
The study of parasites involved specialists-parasitologists. Their job is to detect a parasitic infestation (also called infection or implantation) and prescribe appropriate treatment. Many parasites, such as mites and fleas, are large enough and are therefore visible to the naked eye. They are inconvenient, but they are not dangerous in themselves. However, they can carry potentially very serious diseases. Detection of this is also the responsibility of parasitologists. Moreover, often the only reason for the consultation of a parasitologist is information about parasitic diseases. Parasites are less common in Western countries, as climatic conditions and a smaller population create unfavorable conditions for their transmission and survival. The most common reason for contacting a parasitology laboratory is the appearance of incomprehensible symptoms after returning from a trip. Signs of a parasitic infection can be diarrhea, fever and other, more common symptoms. Parasites are especially common in poor countries with a hot climate, where they are one of the main causes of morbidity. The most common cause of fever and mortality in Africa appears to be malaria; Ankylostomiasis is the most common cause of anemia in the world, and convulsions in adults are most often the result of cysticercosis (a disease caused by the larvae of tapeworms living in the brain). Parasites can cause diarrhea, lesions of the lungs, nervous system and heart - the range of symptoms of parasitic infection is very wide. Until recently, parasites have been a frequent cause of diseases in Europe, but increased living standards and sanitary control measures have reduced the number of parasitic infections. However, this does not mean that such a situation will not arise again - for example, malaria in Europe was eliminated only in the 1940s. At any time, one or more potentially dangerous species of parasites can cause an epidemic that will sweep most of the world's population.
To establish which of the huge number of parasitic infections caused the disease, parasitologists use three methods. The first is a thorough questioning of the patient.
Disease history
Most potentially dangerous parasites live only within certain geographical areas, so before further research it is necessary to find out exactly where the patient lived and where he traveled. It is meaningless to look for a parasite that is spread exclusively in that part of the world where the patient has never been.
Microscopy
The second method of investigation is conventional microscopy. Some parasites can be seen with the naked eye, but most of them are too small for this. However, they are large enough to be visible under a microscope. Parasitologists use special dyes to contrast the samples, but most parasites are visible without it. If a patient experiences diarrhea, parasitologists will analyze the stool specimen. To continue their genus, parasites must multiply, so even if they themselves live within the host organism, at least the presence of eggs will give out their presence.
Antibody tests
The third useful tool is a blood test. The body produces antibodies to protect against parasites, and parasitologists can detect the presence of these antibodies in the patient's blood. This serves as an indirect proof of the presence of the parasite and allows you to make an accurate diagnosis. Malaria is a common disease worldwide, often a cause of death. Parasites are transmitted with mosquito bites. Symptoms of the disease resemble the flu, in the absence of treatment it can lead to coma or death. For the diagnosis, a blood test is performed. Protozoa are single-celled organisms, some of which are capable of causing a bowel disease in a person. Such protozoa as lamblia (Giardia) can cause serious illness in people with weakened immunity, but can easily be detected under a microscope. There are several different types of worms that can cause a person to have an intestinal disorder. Many of them are harmless, but some can cause serious illnesses. Diagnosis can be difficult, to determine the type of pathogen requires the analysis of faeces. Although most parasitic worms, for example bandworms, affect the gastrointestinal tract, other species penetrate the body in other ways, for example through the skin. These infections are found in travelers, as well as in people with weakened immunity.