[Biology Class Notes] on Virus Viral Diseases Pdf for Exam

Introduction To Viral Diseases

Viruses are a type of microorganism which are very small infectious agents. DNA or RNA is the piece of genetic material that is enclosed in a protein coat and these lead to the formation of viruses. In the cells of the body, these viruses invade and use those cell’s components as they help them to multiply. Infected cells often get destroyed by this process and cause incredibly widespread infection which is called viral disease. Viral diseases are also considered contagious because when the virus enters the human body, it begins to multiply and it spreads from one person to the other. Viral diseases include:

Symptoms of Viral Diseases

Viral disease symptoms vary on the basis of virus type, health history and age of the patient, body area infected, and other factors. Symptoms of viral diseases can include:

• Irritability, rash, sneezing.

• Swollen lymph nodes and tonsils. 

• Flu-like symptoms include (headache,   fever, cough,  sore throat, aches, fatigue, and pains).

• Gastrointestinal disturbances like nausea, diarrhea, and vomiting.

• Malaise (general ill feeling).

Serious Symptoms 

In some cases, viral diseases cause serious complications like pneumonia or even life-threatening conditions.

• Change in conscious level or alertness.

• Green, yellowish or brownish phlegm produced by deep, wet chest cough. 

• High fever, seizure, chest pain, stiff neck.

• Lethargy or unresponsiveness

• Shortness of breath, or difficulty in breathing, wheezing.

• Jaundice.

Types of Viral Diseases

1. Respiratory Viral Diseases

 

These diseases commonly affect either the upper or lower part of the body’s respiratory tract. Examples include common cold, influenza, SARS, etc.

Transmission

These Respiratory viruses are either transmitted through droplets generated by sneezing, coughing, or by close contact with contaminated objects. 

Treatment

These infections mostly heal on their own. But some medications can be prescribed that help reduce symptoms like cough suppressants,  Tamiflu (antiviral drug), Nasal decongestants, and pain relievers.

2. Gastrointestinal Viral Diseases

As the name suggests, these infections affect a human’s digestive tract. The viruses that cause the disease are mostly responsible for causing a condition called gastroenteritis, also named as the stomach flu and it is also termed to be contagious. 

For Example astrovirus, norovirus, rotavirus infections

Transmission

These diseases are spread due to contamination of water and food with feces or using personal objects and utensils of infectious persons.

Treatment

No treatment is available.  It resolves on their own.  Meanwhile, the person is advised to take plenty of fluids to make a balance of the loss due to vomiting or diarrhea.

3. Exanthematous Viral Disease

These diseases are caused by Exanthematous viruses that are responsible for causing skin rashes. Most of the viruses of the category are highly contagious. 

For Example Rubella, Smallpox, Chickenpox, Measles.

Transmission

Most of the viruses are transmitted from the droplets generated through sneeze and cough of the infected persons. 

Many diseases like chickenpox and smallpox are spread through the contact of fluid present in the broken skin lesions and diseases like chikungunya are spread through the mosquito bite.

Treatment 

It can be cured by managing symptoms. For Chickenpox, antiviral drugs like acyclovir are given to the patients. Some other fever-reducing medications like acetaminophen are also given to other diseases that come under this category.

List of Viral Diseases in Humans