How dangerous are viral infections? Viral infection: symptoms, signs and treatment in adults
The computer virus was distributed via email in an attached file, and after the user opened this file, the virus sent itself to the first 50 addresses in the email program's address book Microsoft Outlook.
Today " Melissa“You can’t scare anyone anymore. But they will remember her for a long time. Basically, the same as about the next nine viruses. About the latter, by the way, in honor of “ Melissa“And we remember. Read.
Brain
This virus is the most harmless in this hit parade. All because he was one of the first. Distributed via floppy disks. The development lies with the brothers Amjat and Basit Alvi ( Amdjat and Basit Faroog Alvi). These guys started it in 1986. But discover “ something's wrong“The specialists succeeded only a year later in the summer.
They say that the virus infected more than 18 thousand computers in the United States alone. Fun fact: the development was based entirely on good intentions. That is, the brothers wanted to punish local pirates who were stealing their company's software.
And also Brain took pride of place as the world's first stealth virus. When trying to read an infected sector, it “ substituted“ his uninfected original. It was very difficult to catch one.
Source: securelist.com
Jerusalem
The second name is “ Friday 13“. And the first arose thanks to the country of its origin - Israel ( in 1988). Why is this dangerous? Friday“? The one that was downloaded from a floppy disk. And as soon as the time came X ( Friday 13) - the virus immediately deleted absolutely all data from the hard drive. In those days, few people believed in the existence of computer viruses. There were almost no anti-virus programs at all. That's why Jerusalem terrified users.
Source: classifieds.okmalta.com
Morris worm
And this one “ worm“ went on a rampage in November 1988. It blocked the operation of computers with its chaotic and uncontrolled reproduction. Because of him, in fact, the whole ( not too global for those times) Net. Please note: the failure did not last long, but it managed to cause serious damage. Experts valued them at $96 million.
Source: intelfreepress.com
Michelangelo (“March6“)
“Michelangelo“ was rowdy in 1992. It penetrated the boot sector of the disk through floppy disks, and sat quietly there until March 6th arrived. As soon as the time came for X, “ Mark“I immediately formatted the hard drive. Its appearance was beneficial to all companies developing anti-virus software. They then fanned the hysteria to incredible proportions. Although, the virus mocked only 10 thousand machines.
Source: macacosabetudo.com
Chernobyl (CIH)
It was created by a Taiwanese student ( in 1998). This malicious software was named after the latter’s initials. The essence of the software: through the Internet, email and disks, the virus entered the computer and hid inside other programs. And on April 26 it was activated. And it not only erased all the information on the hard drive, but also damaged the computer hardware.
Peak “ Chernobyl“came in April 1999. More than 300 thousand cars were damaged then ( mostly East Asia). And even after everyone trumpeted the information about the presence of such a pest, it hid on computers for a long time and continued its dirty deeds.
Source: softpedia.com
Melissa
We return again to “ Melissa“. It was created by then 30-year-old David Smith. The amount of damage caused to the programmer's brainchild is more than $100 million. For this, the attacker was put behind bars for a term of 46 to 57 months.
Then Smith was released on bail of $100 thousand, and the case began to be put on hold. The hearings have been postponed several times, and the prosecutors who launched the case so loudly have now remained silent. Jim Smith himself and his lawyer are also silent.
Source: jrwhipple.com
ILOVEYOU (“Letter of happiness”)
Someone in 2000 thought of writing a pretty cute virus. It arrived in the mail in the form of a message “I LOVE YOU” with an attached file. Users downloaded it and... A script settled on the hard drive that:
- randomly sent letters in incredible quantities;
- deleted important files on PC.
The results are simply shocking: the damage caused by this “ by letter“, “slammed“ 10% of all computers that existed at that time. In monetary terms it is $5.5 billion.
Computer viruses– special programs that are created by attackers to obtain some benefit. The principle of their operation can be different: they either steal information or encourage the user to perform some actions for the benefit of the attackers, for example, top up an account or send money.
Today there are many different viruses. The main ones will be discussed in this article.
Worm– a malicious program whose purpose is to fill the computer with all sorts of garbage so that it becomes slow and clumsy. The worm is capable of self-replication, but cannot be part of a program. Most often, infection with this virus occurs through emails.
Trojan program (Trojan, Trojan horse)– this program fully lives up to its name. It penetrates other programs and hides there until the host program is launched. Until the host program is launched, the virus cannot cause harm. Most often, a Trojan horse is used to delete, change or steal data. The Trojan cannot reproduce on its own.
Spy programs– these Stirlitz are engaged in collecting information about the user and his actions. Most often, they steal confidential information: passwords, addresses, card/account numbers, etc.
Zombies - malware received this name because it actually turns a computer into a “weak-willed” machine that obeys attackers. Simply put, bad people can control someone's computer through these malware. Most often, the user does not even know that his computer is no longer his only.
Blocker program (banner)– these programs block access to the operating system. When turning on the computer, the user sees a pop-up window, which usually accuses him of something: violating copyrights or downloading pirated software. Next comes the threat of completely deleting all information from the computer. In order to avoid this, the user must top up a specific phone account or send an SMS. Only now, even if the user performs all these operations, the threat banner will not go away.
Boot viruses– affects the boot sector of the hard drive (hard drive). Their goal is to significantly slow down the operating system boot process. After prolonged exposure to these viruses on the computer, there is a high probability that the operating system will not load at all.
Exploit- These are special programs that are used by attackers to penetrate the operating system through its vulnerable, unprotected areas. They are used to infiltrate programs that steal information necessary to gain access to the computer.
Phishing– this is the name for actions when an attacker sends emails to his victims. The letters usually contain a request to confirm personal data: full name, passwords, PIN codes, etc. Thus, a hacker can impersonate another person and, for example, withdraw all the money from his account.
Spyware– programs that send user data to third parties without his knowledge. Spies study the user's behavior and his favorite places on the Internet, and then show advertisements that will definitely be of interest to him.
Rootkit– software tools that allow an attacker to easily penetrate the victim’s software and then completely hide all traces of his presence.
Polymorphic viruses are viruses that disguise themselves and transform. They can change their own code as they work. And therefore they are very difficult to detect.
Software virus– a program that attaches itself to other programs and disrupts their operation. Unlike a Trojan, a computer virus can reproduce and, unlike a worm, to work successfully it needs a program to which it can “stick.”
Thus, we can say that a malicious program (Malware) is any program that was created to provide access to a computer and the information stored in it without the permission of the owner of that computer. The purpose of such actions is to cause harm or steal any information. The term “malware” is a general term for all existing viruses. It is worth remembering that a program that has been infected with a virus will no longer work correctly. Therefore, it needs to be removed and then installed again.
There is an opinion that animals, plants and humans predominate in numbers on planet Earth. But this is actually not true. There are countless microorganisms (microbes) in the world. And viruses are among the most dangerous. They can cause various diseases in humans and animals. Below is a list of the ten most dangerous biological viruses for humans.
10 Hantaviruses
Hantaviruses are a genus of viruses transmitted to humans through contact with rodents or their waste products. Hantaviruses cause various diseases belonging to such groups of diseases as “hemorrhagic fever with renal syndrome” (mortality on average 12%) and “hantavirus cardiopulmonary syndrome” (mortality up to 36%). The first major outbreak of disease caused by hantaviruses, known as Korean hemorrhagic fever, occurred during the Korean War (1950–1953). Then more than 3,000 American and Korean soldiers felt the effects of a then unknown virus that caused internal bleeding and impaired kidney function. Interestingly, it is this virus that is considered the probable cause of the epidemic in the 16th century that exterminated the Aztec people.
9 Influenza virus
Influenza virus is a virus that causes an acute infectious disease of the respiratory tract in humans. Currently, there are more than 2 thousand of its variants, classified into three serotypes A, B, C. The group of viruses from serotype A, divided into strains (H1N1, H2N2, H3N2, etc.) is the most dangerous for humans and can lead to epidemics and pandemics. Every year, between 250 and 500 thousand people worldwide die from seasonal influenza epidemics (most of them children under 2 years of age and elderly people over 65 years of age).
8 Marburg virus
Marburg virus is a dangerous human virus first described in 1967 during small outbreaks in the German cities of Marburg and Frankfurt. In humans, it causes Marburg hemorrhagic fever (mortality rate 23-50%), which is transmitted through blood, feces, saliva and vomit. The natural reservoir for this virus is sick people, probably rodents and some species of monkeys. Symptoms in the early stages include fever, headache and muscle pain. In the later stages - jaundice, pancreatitis, weight loss, delirium and neuropsychiatric symptoms, bleeding, hypovolemic shock and multiple organ failure, most often the liver. Marburg fever is one of the top ten deadly diseases transmitted from animals.
7 Rotavirus
Sixth on the list of the most dangerous human viruses is Rotavirus, a group of viruses that are the most common cause of acute diarrhea in infants and young children. Transmitted by the fecal-oral route. The disease is usually easy to treat, but kills more than 450,000 children under five worldwide each year, most of whom live in underdeveloped countries.
6 Ebola virus
Ebola virus is a genus of virus that causes Ebola hemorrhagic fever. It was first discovered in 1976 during an outbreak of the disease in the Ebola River basin (hence the name of the virus) in Zaire, DR Congo. It is transmitted through direct contact with the blood, secretions, other fluids and organs of an infected person. Ebola fever is characterized by a sudden increase in body temperature, severe general weakness, muscle pain, headaches, and sore throat. Often accompanied by vomiting, diarrhea, rash, impaired renal and liver function, and in some cases internal and external bleeding. According to the US Centers for Disease Control, in 2015, 30,939 people were infected with Ebola, of whom 12,910 (42%) died.
5 Dengue virus
Dengue virus is one of the most dangerous biological viruses for humans, causing dengue fever, in severe cases, which has a mortality rate of about 50%. The disease is characterized by fever, intoxication, myalgia, arthralgia, rash and swollen lymph nodes. It is found mainly in the countries of South and Southeast Asia, Africa, Oceania and the Caribbean, where about 50 million people are infected annually. The carriers of the virus are sick people, monkeys, mosquitoes and bats.
4 Smallpox virus
Smallpox virus is a complex virus, the causative agent of a highly contagious disease of the same name that affects only humans. This is one of the oldest diseases, the symptoms of which are chills, pain in the sacrum and lower back, rapid increase in body temperature, dizziness, headache, vomiting. On the second day, a rash appears, which eventually turns into purulent blisters. In the 20th century, this virus claimed the lives of 300–500 million people. About US$298 million was spent on the smallpox campaign from 1967 to 1979 (equivalent to US$1.2 billion in 2010). Fortunately, the last known case of infection was reported on October 26, 1977 in the Somali city of Marka.
3 Rabies virus
The rabies virus is a dangerous virus that causes rabies in humans and warm-blooded animals, which causes specific damage to the central nervous system. This disease is transmitted through saliva from the bite of an infected animal. Accompanied by an increase in temperature to 37.2–37.3, poor sleep, patients become aggressive, violent, hallucinations, delirium, a feeling of fear appear, soon paralysis of the eye muscles, lower extremities, paralytic respiratory disorders and death occurs. The first signs of the disease appear late, when destructive processes have already occurred in the brain (swelling, hemorrhage, degradation of nerve cells), which makes treatment almost impossible. To date, only three cases of human recovery without vaccination have been recorded; all others ended in death.
2 Lassa Virus
Lassa virus is a deadly virus that is the causative agent of Lassa fever in humans and primates. The disease was first discovered in 1969 in the Nigerian city of Lassa. It is characterized by a severe course, damage to the respiratory system, kidneys, central nervous system, myocarditis and hemorrhagic syndrome. It is found mainly in West African countries, especially in Sierra Leone, the Republic of Guinea, Nigeria and Liberia, where the annual incidence ranges from 300,000 to 500,000 cases, of which 5 thousand lead to the death of the patient. The natural reservoir of Lassa fever is polymammated rats.
1 Human immunodeficiency virus
Human immunodeficiency virus (HIV) is the most dangerous human virus, the causative agent of HIV infection/AIDS, which is transmitted through direct contact of mucous membranes or blood with bodily fluid of the patient. During HIV infection, the same person develops new strains (varieties) of the virus, which are mutants, completely different in reproduction speed, capable of initiating and killing certain types of cells. Without medical intervention, the average life expectancy of a person infected with the immunodeficiency virus is 9–11 years. According to 2011 data, 60 million people worldwide have become infected with HIV, of which 25 million have died, and 35 million continue to live with the virus.
They are completely dependent on cells (bacteria, plant or animal) for reproduction. Viruses have an outer shell of protein and sometimes a lipid and a core of DNA or RNA. For infection to occur, the virus first attaches to a host cell. The viral DNA or RNA then enters the host cell and is separated from the outer envelope (viral cecapsulation) and replicated to the host cell using certain enzymes. Most RNA viruses copy their nucleic acid in the cytoplasm, while most DNA viruses copy it in the nucleus. The host cell typically dies, releasing new viruses that infect other host cells.
The consequences of viral infection vary greatly. Many infections cause acute illness after a short incubation period, and some are asymptomatic or cause minor symptoms that cannot be recognized except in retrospect. With many viral infections, recovery occurs under the influence of the body's defenses, but some become latent. In latent infection, the viral RNA or DNA remains in the host cells without causing disease for a long time, sometimes for many years. Most often, infection from person to person occurs during the asymptomatic period with hidden, latent forms of viral infections. Various triggers can cause re-activation of the process, this especially often occurs during immunosuppression.
Common viruses that remain latent are:
- Herpes viruses.
- Papovaviruses.
Some diseases are caused by reactivation of the virus in the central nervous system after a very long period of latency. These diseases include progressive multifocal leukodystrophy (polyomavirus K), subacute sclerosing panencephalitis (measles virus), and progressive rubella panencephalitis (rubella virus). Spastic pseudosclerosis and bovine spongiform encephalopathy were previously classified as slow viral diseases due to long incubation periods (years), but are now known to be caused by prions; Prions are protein pathogens that are not bacteria, fungi or viruses and that do not contain genetic material.
Several hundred different viruses can infect people. Such viruses are often spread through respiratory and intestinal secretions. Some are transmitted through sexual contact and blood transfusions. Some viruses are transmitted by arthropod vectors. Viruses are distributed throughout the world, but their pathogenicity is limited by innate resistance, resistance, post-vaccination immunity, sanitary and other health system control methods, and prophylactic antiviral drugs.
Zoonotic viruses carry out their biological cycles mainly in animals; humans are secondary or accidental hosts. These viruses exist in a specific environment that is able to support their natural cycles that differ from humans (vertebrates, arthropods, or both).
Viruses and cancer. Some viruses are oncogenic and predispose to certain cancers:
- Papillomavirus: cervical and anal carcinoma.
- Human T-lymphotropic virus 1: certain types of human leukemia and lymphoma.
- Epstein-Barr virus: nasopharyngeal carcinoma, Burkitt's lymphoma, Hodgkin's lymphoma and lymphomas in organ transplant recipients and the immunocompromised.
- Hepatitis B and C viruses: hepatocellular carcinoma.
- Human herpesvirus 8: Kaposi's sarcoma, primary lymphomas and multicentric Castleman disease (lymphoproliferative disease).
Types of viral diseases
Classification of viral infections according to the organ system affected (eg, lung, GI, skin, liver, CNS, mucosal membranes) can be clinically useful, although certain viral diseases (eg, mumps) are difficult to classify.
Respiratory infections. The most common viral infections are probably acute respiratory infections. Respiratory infections are more likely to cause severe symptoms in infants, the elderly, and patients with lung or heart problems.
Gastrointestinal infections. The age group affected primarily depends on the virus:
- Rotavirus: children.
- Norovirus: older children and adults.
- Astrovirus: usually infants and young children.
- Adenovirus 40 and 41: infants.
- Pathogens similar to coronavirus: infants.
Localized epidemics may occur in children, especially during colder seasons.
The main symptoms are vomiting and diarrhea.
Rotavirus vaccine, which is effective against most pathogenic strains, is part of the recommended childhood vaccination schedule. Hand washing and good sanitation can help prevent the spread.
Exanthematous infections. Some viruses cause only skin lesions (as with molluscum contagiosum and warts); others may cause systemic manifestations or skin lesions on various parts of the body. Transmission typically occurs from person to person; The carrier of alpha viruses is the mosquito.
Liver infections. At least 5 specific viruses (hepatitis viruses A, B, C, D and E) can cause hepatitis; each causes a specific type of hepatitis. The hepatitis D virus can only infect people if there is hepatitis B.
Other viruses can also attack the liver. Common examples are cytomegalovirus, Epstein-Barr virus, and yellow fever virus. Less common examples are echovirus, coxavirus, and the herpes simplex, measles, rubella, and varicella viruses.
Neurological infections. Most cases of encephalitis are caused by viruses. Many of these viruses infect humans through the bites of arthropods, mainly mosquitoes and blood-feeding ticks; these viruses are called arboviruses. For such infections, prevention includes avoiding mosquito (mosquito) and tick bites.
Hemorrhagic fever. Certain viruses cause fever and a tendency to bleed or bleed. Spread by mosquitoes, ticks, or contact with infected animals (eg, rodents, monkeys, bats) and people.
Infections of the skin or mucous membranes. Some viruses cause lesions of the skin or mucous membranes, which recur and can become chronic. Infections affecting the skin and mucous membranes are the most common type of herpes simplex viral infection. The human papillomavirus causes warts. Transmission by person-to-person contact.
Diseases with multiple lesions of various systems and organs. Enteroviruses, which include coxsackieviruses and echoviruses, can cause various multisystem syndromes, as can cytomegaloviruses.
Nonspecific febrile illness. Some viruses cause nonspecific symptoms, including fever, malaise, headaches, and myalgia. Transmission usually occurs through insects or arthropods.
Rift Valley fever rarely progresses to eye lesions, meningoencephalitis, or the hemorrhagic form (which has a 50% mortality rate).
Virus diagnostics
Some viral diseases can be diagnosed clinically by familiar symptoms and syndromes (eg, measles, rubella, roseola infantum, erythema infectiosum, and varicella) or epidemiologically during epidemic outbreaks (eg, influenza). A clear laboratory diagnosis is needed primarily when specific treatment may be helpful or when the pathogen may be a public health threat (eg, HIV). Typical hospital laboratories can test for individual viruses, but for relatively rare diseases (eg, rabies, Eastern equine encephalitis), materials must be sent to public health laboratories or the Centers for Disease Control and Prevention.
Serological testing in the acute and convalescent phases is sensitive and specific but slow; faster diagnosis can sometimes be made using culture methods, PCR, and sometimes histochemical methods using electron microscopy to detect viral antigens.
Treatment of viruses
Antiviral drugs. Progress in the use of antiviral drugs is rapid. Antiviral chemotherapy can be aimed at various phases of viral replication: interfere with the process of attachment of the virus particle to the membranes of the host cell or decapsulation of the nucleic acids of the virus, inhibit the cellular receptor or factor necessary for viral replication, block specific virus-encoded enzymes and proteins that are produced in host cells and which are important for viral replication rather than normal host cell metabolism.
Antivirals are most often used therapeutically or prophylactically against herpesviruses (including cytomegalovirus), respiratory viruses, and HIV. However, some drugs are effective against different types of viruses.
Interferons. Interferons are substances produced by infected host cells in response to viral or other foreign antigens. There are many different interferons that have numerous
effects such as blocking viral RNA translation and transcription and stopping viral replication without interfering with normal host cell function. Sometimes interferons are attached to polyethylene glycol (pegylated compounds), which gives a slow and prolonged release of interferon.
Viral diseases that can be treated with interferon:
- Chronic hepatitis B and C.
- Condyloma acuminata.
- Hairy cell leukemia.
- Kaposi's sarcoma.
Depression and, with large doses, bone marrow suppression are also possible.
Virus prevention
Vaccines. Vaccines work to stimulate the innate immune system. Vaccines used include hepatitis A, hepatitis B, human papillomavirus, influenza, measles, mumps, polio, rabies, rotavirus, rubella, chickenpox and yellow fever. adenovirus and smallpox vaccines are available but are used only in at-risk groups (eg, army recruits).
Immunoglobulins. Immunoglobulins are available for passive immunoprophylaxis in selected situations. They can be used when there is a risk of infection (for example, hepatitis A), after infection (for example, rabies or hepatitis) and to treat a disease (for example, eczema vaccinatum).
Preventive measures. Many viral infections can be prevented by common preventive measures (which vary depending on how the pathogen is transmitted). Hand washing, proper food preparation and water handling, avoiding contact with sick people and practicing safe sex are important. Regarding infections that are carried by insects (eg mosquitoes, ticks), it is important to protect yourself from contact with them.
Doctors classify all infections as rapid and slow. The slower the bacteria, the more dangerous it is to human life. This is justified by the fact that these microorganisms have the greatest destructive factor and also do not have pronounced symptoms.
Let's look at the main infections:
- Herpetic. Herpes is present in the body of every person, but it worsens only if a provocateur appears. In appearance, herpes can be identified by characteristic blisters on one or another part of the patient’s body.
- Acute respiratory viral infection. This microbe enters the human respiratory tract and then infects them. The symptoms are similar to the flu or a common cold. The most dangerous part of the disease is the possibility of getting chronic bronchitis or pneumonia.
- Encephalitis. This microbe affects the human brain, which leads to the destruction of the central nervous system and consciousness. This disease has an extremely high mortality rate. Once infected, patients often fall into a coma, experience seizures and paralysis of some limbs. Also, this microbe contributes to the development of multiple organ failure, the result is death in 9 out of 10 cases.
- Hepatitis. Infection of the body with such a microbe leads to damage to the liver tissue. Subsequently, disturbances and complications in the functioning of this organ develop. These symptoms can lead to a disastrous outcome.
- Polio. After the disease, a person will experience constant convulsive attacks, and subsequently develop inflammation of the brain and loss of consciousness. As a result of these symptoms, paralysis is possible. The disease is extremely dangerous, as it leads to disability of the patient.
- Meningitis. This microorganism penetrates under the cerebral cortex and infects the cerebrospinal fluid. Subsequently, the virus “travels” throughout the human circulatory system. Can lead to disturbances of consciousness and atrophy of the muscles of the arms or legs, even despite correct therapy.
- Measles. After the onset of the disease, the patient develops a red rash on certain parts of the body, a cough and a fever. In itself, the microorganism is not particularly dangerous, but if you do not treat the infection in time, you can get complications in the form of encephalitis or meningitis.
- STD. Sexually transmitted diseases have been around for a long time. Previously, they were considered extremely dangerous, but with the current level of medicine, they can be completely cured. To completely eradicate the disease, symptoms must be identified in a timely manner.