Viruses can cause a wide variety of diseases, depending on the type of infection and the characteristics of the infected tissue. What are the viruses in humans? There are a lot of them, and throughout their lives, people in one way or another come into contact with most pathogens of infection. The diseases they cause range from relatively easily tolerated to deadly. The most common viruses in the world are those that lead to colds, flu, intestinal infections, and hepatitis.
Viruses and colds
A common cold (as infectious diseases such as flu, SARS, laryngitis, pharyngitis are called in everyday life) remains one of the most common human ailments. In the United States alone, about a billion cases of SARS are recorded each year. Viral infection of the mucous membrane of the nasal passages leads to a runny nose, lacrimation, sore throat and sneezing. The course of the disease lasts from one to two weeks. According to statistics, more than 200 of the known strains can lead to colds. What types of viruses are the most common causative agents of acute respiratory viral infections? These are various rhinoviruses, adenovirus, coronavirus, Coxsackie virus, echovirus, enterovirus, orthomyxovirus, paramyxovirus and respiratory syncytial virus.
Flu virus
Influenza is caused by three types of microorganisms. Types A and B lead to seasonal infections characteristic of the period beginning in late autumn and ending in early spring. Type C virus infections are less common and most often cause a mild illness. The most common flu symptoms include body aches, fever, tiredness, headache, sore throat, dry cough, and nasal congestion. Vaccines against influenza are a means of protection against viral infections of types A and B.
Intestinal viruses
What viruses are in the digestive system and what are their characteristic signs? Microorganisms of this type penetrate into the tissues of the stomach and intestines, causing viral gastroenteritis. Symptoms common to the disease include abdominal pain, colic, diarrhea, nausea, and vomiting. In young children, including infants, rotavirus is often the cause of gastroenteritis. Such an infection manifests itself in the form of fever, vomiting, and watery diarrhea. Norovirus is no less common pathogen of infectious diseases, affecting both children and adults. However, in younger patients, the symptom of ailment, such as diarrhea, almost always predominates, while for adults, incessant vomiting is more characteristic. Other known intestinal viruses include strains of adenovirus, sapovirus and astrovirus.
Hepatitis viruses
The causative agents of infection of this species affect the liver, initiating inflammatory processes. Five different viruses leading to hepatitis are known to science; they got names based on the letters of the Latin alphabet from A to E. If you are interested in what hepatitis viruses are in developed countries, then, according to statistical studies, types A, B and C prevail in countries with developed infrastructure and medicine. The hepatitis A virus penetrates into the body when digesting food or water contaminated with feces. It causes one brief episode of hepatitis. Type B strains can cause acute or chronic liver infections. Microorganisms are found in the blood and seed. The most common cases of hepatitis B infection include sexual intercourse, sharing the same syringes with drugs, and mother-to-child transmission during pregnancy and childbirth. Type C virus spreads through contact with the patient’s blood. Repeated use of syringes by different people when using drugs is the most common way to transmit the infection. Hepatitis C, as a rule, takes a chronic form, however, adequate treatment in many cases can alleviate the course of the disease.
Other viruses
What are the viruses in humans besides the above? If you print a complete list of titles, you will have to publish several volumes of the list. Moreover: every year, scientists discover new types, hitherto unknown. Some strains are very rare, but pose a great danger due to their potential mortality. These are, for example, Ebola or rabies viruses. Other microorganisms are quite common and are the root cause of a huge number of diseases. For those who are interested in what types of viruses a person has, just open any popular medical directory. So, a good example of a common type of infection is herpes viruses, which cause simple (vesicle) herpes on the lips, genital herpes, infectious mononucleosis, chicken pox, herpes zoster, and many other ailments. The human papilloma virus causes not only the appearance of ordinary warts on the skin, but also the development of cervical cancer.
What viruses have been in humans lately? Infections of the latest types - HIV, acute respiratory syndrome (SARS) and the Middle East respiratory syndrome (MERS coronavirus) - remain a serious problem, since today there is no truly effective treatment for these diseases.
Diagnostics
Diagnosis of a viral infection is mainly based on an initial physical examination and analysis of a medical history. For example, a disease like the flu is easy to recognize, and most people are familiar with its manifestations. Detection of some other infections, however, may require additional diagnostic tests.
Diagnostic options for viral infection
Since the answer to the question of what kind of viruses a person has involves thousands of answers, sometimes it is not enough just to examine the patient and study his medical history. In such cases, doctors prescribe one or more of the following studies:
- blood tests to check for antibodies to viruses or to detect antigens directly;
- cultivation of blood components, body fluids and other materials taken from the affected area;
- cerebrospinal puncture for cerebrospinal fluid analysis;
- polymerase chain reaction technique to create multiple copies of viral genetic material for faster and more accurate identification of the virus;
- magnetic resonance imaging to detect the inflammatory process in the temporal lobes of the brain.
Symptoms
What are the viruses in humans? The list is incredibly extensive, but the symptoms of many infections can be systematized to create a single list. So, signs of a virus infection may include:
- increase in body temperature;
- muscle pain;
- cough;
- sneezing
- runny nose;
- chills;
- diarrhea
- vomiting
- skin rash;
- feeling of weakness.
More severe symptoms appear as follows:
- neck stiffness;
- dehydration;
- cramps
- paralysis of the limbs;
- loss of orientation in space;
- back pain;
- loss of sensation;
- disorders of the bladder and intestines;
- drowsiness, which can turn into a coma or death.
Infection: viral or bacterial?
What are the viruses in humans? The names are unlikely to say anything to a layman, but viral and bacterial infections should be distinguished.
Infections of both types are the causes of deterioration of well-being and the development of various diseases. However, there is a difference between them. A viral infection, as its name says, begins with exposing the body to a virus, the smallest intracellular agent that is even smaller than a bacterium. In addition, it is in a protective shell, which means it is more difficult to destroy. The virus enters a living cell and embeds its genome in its genetic apparatus. Such infectious agents are non-cellular particles and need foreign cells to reproduce. If you are interested in what viruses are, the names that you will find in this article will most likely point you to the main infection sites. This is the nose, throat and upper respiratory tract. Virus strains can cause both the common cold and AIDS.
In order to initiate a bacterial infection, a pathogenic bacterium must gain access to the body through contaminated water, cuts on the skin, or contact with an infected person or contaminated objects. One of the fundamental differences between the two types of infections is that bacteria can enter the body through contact with inanimate objects, including doorknobs and table surfaces, while viruses cannot. Another difference is the nature of the microorganism: the bacterium is a cell and multiplies by division, while the virus dies without a host carrier. Most often, bacteria enter the body through the respiratory tract or the gastrointestinal tract. Some bacterial infections are contagious (such as, for example, acute pharyngitis - streptococcal throat inflammation).
Cause of viral infection
The question of what viruses a person has is especially acute because the cells of the human body are susceptible to them. When exposed to viral particles, the immune system tries to destroy the source of danger and remove foreign strains from the body.
Reduced immunity allows the virus to attach to accessible cells faster. Weak immunity also contributes to the multiplication of the virus, until the body's defense system cope with the parasite.