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List of Viral Diseases in Humans

Virus

Viruses are tiny particles that are made up of DNA or RNA (genetic materials) covered by a protein layer, and some of them also possess a fatty ‘envelope’ covering. Viruses are dependent on the hosts (organisms whom they attack or infect) for their living as they are not capable of reproducing on their own. Generally, viruses got a bad reputation because of it’s deadly infections, but they also play certain crucial roles for humans, plants, animals, and the environment. For instance, some viruses prevent the hosts from catching other infections. Viruses also take part in the evolution process by transmitting genes between various species. Scientists use them to add new genes into cells during biomedical research.

Some microbiologist doesn’t agree that viruses are alive, whereas some say they are alive by offering these reasons:

• They replicate themselves to revive
• They obtain energy from their hosts

Here are reasons why some microbiologists deny that viruses are alive:

• Virus don’t have any cells; it only has genetic materials enclosed by the protein covering
• They are incapable of reproduction and require host cells

What is Viral Infection?

A viral infection is a multiplication of deleterious viruses within a person’s body. Viruses are unable to reproduce in the absence of the host. It affects the host by inserting their genetic materials into the cells and taking over the cell’s interior mechanism to produce enough particles of the virus. The virus produces more duplicates and bursts the host cell during active viral contamination. This helps to set the recently produced virus particles free. At other times, the host cell is “bud” off by the virus particles before getting destroyed by the same. In one way or another, new virus particles subsequently transmit the infection to other cells freely. As the consequences of cell and tissue destruction and the related response from the immune system, several viral diseases develop in the body.

The transmission of viral infections may take place in many ways, such as it can be spread through touch, saliva, or the air. Some viruses also get transmitted via sexual contact and by using infected needles. Ticks and mosquitoes are some of the insects that behave as vectors for spreading viral infection. Vectors transmit the virus from one host to another. Contaminated food and water are most likely to spread viral diseases.

1. Respiratory viral diseases

Respiratory viral diseases are infectious. It generally infects the upper and lower parts of a person’s respiratory tract.

Examples of respiratory diseases are:

• Flu
• Respiratory syncytial virus infection
• Common cold
• Parainfluenza virus infection
• Adenovirus infection
• SARS (severe acute respiratory syndrome)

Clinical Manifestation:

• Runny or stuffy nose
• Fever
• Coughing or sneezing
• Body aches

Transmission:

Respiratory viruses are transmitted via droplet infection (coughing or sneezing). A person may catch the infection if any person with viral infection sneezes or coughs near them, and unknowingly they inhale these droplets. Contaminated Objects, like tabletops, doorknobs, and one’s own daily use items, can also transmit viruses if we use them and then touch our eyes or nose.

Treatment

These types of viral diseases cure on their own. But OTC (over-the-counter) drugs such as decongestants, antitussives, and analgesics help to lessen the symptoms.

Additionally, Tamiflu is an antiviral medicine that is recommended for a person suffering from the flu.

Precautions:

• Maintaining good personal hygiene is the best way to prevent respiratory viral diseases
• Wash hands frequently and cover your mouth while you’re coughing or sneezing
• To avoid interactions with the person showing symptoms of respiratory diseases

2. Hemorrhagic viral diseases

Hemorrhagic viral diseases are serious conditions where a person’s circulatory system is damaged.

Examples of hemorrhagic viral diseases are:

• Dengue fever
• Marburg hemorrhagic fever
• Yellow fever
• Ebola
• Crimean- Congo hemorrhagic fever
• Lassa fever

Clinical Manifestation:

• Weakness
• High fever
• Bleeding in internal organs
• Bleeding under the skin
• Body aches
• Bleeding from the mouth or ears

Transmission:

Diseases like dengue and yellow fever are transmitted from a bite of infected insects, whereas diseases like Ebola are spread to a person when he comes in contact with the blood and body fluid of an infected person. Dried feces and urine of a rodent containing viruses cause Lassa fever when inhaled or consumed by someone unknowingly.

Treatment:

However, there is no exact regimen and cure for hemorrhagic viral diseases.

Keeping the body hydrated is very important for a person suffering from these infections, and sometimes IV (intravenous) fluids are recommended to a patient for maintaining fluid-electrolyte balance. In some cases, ribavarin, an antiviral drug, is prescribed.

Precautions:

People living or working in an area where these diseases are common can adopt the following preventions to decrease the risk:

• Always wear protective clothing and use insect repellent. Try not to get bitten by insects such as ticks and mosquitoes
• Protect yourself from viral infection while being in contact with an infected person by wearing proper protection like a face shield, gloves, and glasses.
• Keep food covered, dispose garbage regularly, and keep doors and windows secure to prevent rodent infestation.

Researchers are continuously working to develop vaccines for various hemorrhagic viruses. Recently, the vaccine for yellow fever has been provided to people moving or visiting areas where this disease is common.

3. Gastrointestinal viral diseases:

These diseases affect your digestive tract, and the viruses responsible for the infection are contagious and commonly lead to a condition known as gastroenteritis (stomach flu).

Examples of gastrointestinal viral diseases are:

• Rotavirus infection
• Astrovirus infection
• Norovirus infection
• Some adenovirus infection

Clinical Manifestation:

• Nausea and vomiting
• Diarrhea
• Abdominal cramps

Transmission

During the bowel movement, gastrointestinal viruses are shed in the fecal matter. Food or water polluted by stool can transmit the viruses to other people. If a person shares utensils or personal items with anyone with a viral infection can also get caught by the virus.

Treatment

There is no treatment for gastrointestinal viral infection as, in various cases, they heal on their own in 2 -3 days only. A person should drink plenty of fluids to restore the loss that occurred due to vomiting and Diarrhea.

Prevention

• These infections can be prevented by proper handwashing, especially after using the bathroom.
• Wipe down the contaminated areas and avoid sharing personal items and utensils.
• A vaccine for rotavirus is available and mentioned in the child’s immunization schedule.

4. Hepatic viral diseases

Inflammation of the liver, basically known as viral hepatitis, is a serious medical condition caused by hepatic viral diseases. Hepatitis A, B, and C are some of the most common types of viral hepatitis.

It is worth bearing in mind that infection caused by viruses like the yellow fever virus and cytomegalovirus may create certain complications to the liver.

Examples of hepatic viral diseases are:

• Hepatitis A
• Hepatitis B
• Hepatitis C
• Hepatitis D
• Hepatitis E

Clinical Manifestation

• Fever
• Loss of appetite
• Abdominal pain
• Jaundice, yellowing of your skin and eyes
• Fatigue
• Nausea and/or vomiting
• Clay-colored bowel movements
• Dark urine
• Joint pain

Transmission

Hepatitis B and C can be spread from one individual to another through body fluids, for instance, transfusion of blood. Also, sharing personal items such as razors and needles that came into contact with blood transfers the virus. Hepatitis B also spreads by maintaining sexual contact with an infected person, and if someone already has hepatitis B can develop hepatitis D in the future. Consumption of food and water polluted by feces from someone having a virus can cause hepatitis A and E.

Treatment

1. Hepatitis B, C, and D are treated by managing the clinical signs and symptoms. Medications like antiviral drugs are recommended by the physician.
2. Hepatitis A and E are treated by taking supportive measures like saying no to alcohol, drinking plenty of fluids, and taking proper rest and sleep.

Prevention

Vaccines are available for both hepatitis A and hepatitis B.

Some other precautions to prevent viral hepatitis are:

• Do not share razors or needles
• Practice safe sex
• Do not consume food and drinks that may be contaminated by feces

5. Neurologic viral diseases

Some viruses infect the brain and tissues surrounding it, which leads to neurologic viral diseases.

Examples of neurologic viral diseases are:

• Viral meningitis
• Rabies
• Polio
• Viral encephalitis

Clinical Manifestation

• Confusion
• Seizures
• Fever
• Drowsiness
• Coordination problems

Transmission

Various neurological viruses transmit after getting bitten by an infected animal or bugs, like ticks and mosquitoes.

While viruses like poliovirus and enterovirus are communicable and transmitted when an individual comes in close contact with a person with a virus. These viruses can also get spread through contaminated items.

Treatment

1. There is no particular treatment available for a person with mild meningitis or encephalitis. Having OTC anti-inflammatories, taking proper rest, and drinking plenty of water helps to relieve the pain or headaches. In certain cases, physicians may recommend taking antiviral medication.
2. Person suffering from polio or serious viral meningitis or encephalitis may need further medical assistance like breathing assistance and intravenous fluids.
3. If any animal bites someone and is under suspicion to have rabies, a series of shots will be administered to the person, which will prevent the rabies virus from spreading in the body.

Prevention

• Maintaining good hygiene
• Try to avoid close contact with the person having the virus
• Preventing ourselves from getting bitten by the insects
• Keep your pets vaccinated to decrease the spread of rabies and also stay away from wild animals
• Get a vaccine for both poliovirus and mumps virus

6. Cutaneous viral diseases

Lesions and papules form on the skin because of cutaneous viral diseases. In the majority of cases, lesions remain on the skin for a long period of time or reappear again after disappearing for a short time.

Examples of cutaneous viral diseases are:

• Oral herpes
• Molluscum contagiosum
• Warts, including genital warts
• Genital herpes

Transmission

These viruses are transferable and generally spread through close contact with a person having a virus. Touching or using objects such as towels or faucet handles that are contaminated by the virus can cause the infection.

Treatment

• Warts or molluscum contagiosum form papules that heal on their own. A simple-in-office procedure like cryotherapy can also be done to remove the papules.
• Antiviral drugs such as acyclovir are prescribed by the doctor to reduce or prevent outbreaks.

Prevention

• Maintaining a good hygiene routine
• Avoid sharing personal items
• Close contact with the person having active lesions should be avoided to lessen the risk of developing the infection.

7. Exanthematous viral disease

Exanthematous viral diseases give rise to skin rashes, and most of them lead to other added symptoms too. The majority of the viruses in this classification are extremely communicable.

Examples of exanthematous viral diseases are:

• Rubella
• Smallpox
• Chikungunya virus infection
• Roseola
• Measles
• Fifth disease

Clinical Manifestation

• Pink-to-red spots or bumps on the trunk, legs, and arms
• A rash may be itchy
• Fatigue
• Fever
• Loss of appetite
• Pain
• Irritability

Transmission

• These viruses transmit through the droplets from the sneeze or cough of an infected person.
• Viral diseases like smallpox and chickenpox spread when a person comes into contact with fluid in broken derm lesions.
• People suffering from chickenpox develop shingles eventually as it is a regeneration of the virus ‘varicella- zoster’ that has been resting in the body’s cell.
• Chikungunya virus transmitted via mosquito bite is a non-communicable disease that cannot be spread from one person to another.

Treatment

Treatment of these diseases targets managing the clinical manifestation. Medications like acetaminophen help to reduce fever and some other distressing symptoms.

The person having chickenpox or shingles infections is recommended to take antiviral medications like acyclovir.

Prevention

Vaccines for measles, chickenpox, smallpox, and shingles are available. The risk of developing chikungunya virus infection can be prevented by protecting against mosquito bites.

Conclusion

There are several viral diseases, such as stomach flu or the common cold, that are minor and go away on their own in a few days only. However, some are very serious.

Basically, viral diseases don’t respond to antibiotics, and their treatment generally focuses on the management of their clinical manifestation. One can support their immune system by taking proper rest and sleep, maintaining good hygiene, taking a balanced diet, and keeping the body hydrated.

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