Human Diseases

BiologyHuman biology


The disease is a broad concept of an illness that some organisms have. Injury is another broad concept of an injury that a human can have. Humans can get diseases or are susceptible to them, and most humans can get injured or sustain injuries.

What is a Disease?

A disease is a state of abnormal health where the structure and function of an organism are impaired due to infection, genetic defect, or environmental influences. Diseases may affect people physically, mentally, or both.

The World Health Organization definition of disease is "Any deviation from or interruption of the normal structure or function of any part, organ or system which occurs in any organism". Since this definition does not specify any pathology, it could be applied to plants as well as animals

There are many types of diseases, including bacterial diseases (bacterial infections), viral diseases (viral infections), fungal diseases (fungal infections), protozoan diseases (protozoan infections) and parasitic diseases (parasitic infections).

Communicable Diseases

The term communicable disease refers to a disease that can be transmitted from one person to another. The most common types of communicable diseases are bacterial infections, viral infections, and parasitic infections. Communicable diseases are commonly spread through physical contact with an infected person or contaminated objects or fluids.

Many communicable diseases have no symptoms in their early stages. They may include fever, rash, headache, muscle aches, and fatigue when symptoms occur. Other signs and symptoms depend on the type of infection involved. Some infections can cause serious illness or even death if not treated promptly with antibiotics or other medications.

Causes Of Communicable Diseases

A communicable disease is a disease that can be passed from one person to another. The following are some of the most common causes of communicable diseases.


Viruses are the smallest living organisms. They cannot be seen by the naked eye and do not have a nucleus or any other organelles. A virus is composed of genetic material, and protein that is surrounded by a protective coat called a capsid. The capsid comprises protein molecules that form a shell-like structure around the virus' genetic material. Viruses cannot reproduce on their own. Instead, they infect other cells and make them produce more viruses.

Many viruses cause communicable diseases (also known as contagious diseases) when they are transmitted from one person to another through direct contact with infected body fluids, such as blood, saliva, urine, semen or other secretions (such as feces). Some communicable diseases can also be transmitted when infected materials touch broken skin or mucous membranes (the moist lining of the mouth, nose and eyes).


The bacteria that cause communicable diseases are generally extremely small and simple. However, they can cause very serious illnesses.

Bacteria are microscopic single-celled organisms that can survive in nearly any environment, including the human body

Bacteria live in colonies and reproduce by dividing in two or by forming spores that can survive harsh conditions. Bacteria are classified according to their shape and the way they move. Some have flagella (tails) for movement; others do not. Some bacteria have capsules surrounding them; others do not.

There are many types of bacteria that live on our bodies without causing any problems at all (such as "good" bacteria found in yogurt). Some bacteria are beneficial to us because they help us digest food or fight off disease-causing germs. Other bacteria cause diseases when they get into our bodies through cuts or other openings in our skin or through ingestion (swallowing).


A protozoan is a microscopic single-celled organism. Like other eukaryotic microorganisms, protozoa are unicellular eukaryotic organisms that have motile stages in their life cycles. The word "protozoa" comes from the Greek words πρώτος (protos), meaning "first", and zoē (zōē) meaning "animal". The study of protozoa is called protozoology or protozoologyt.

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Protozoa are typically a few micrometers in size but can include some species which reach up to two millimeters in length. They are distinguished from other microorganisms due to their lack of cell walls and a different membrane system, among other characteristics. The individual may be predatory or parasitic and comprises an assortment of flagellated or amoeboid stages in its life cycle, though some species reproduce by fission rather than sexual means.


Fungi are eukaryotic microorganisms that do not move. They are distinct from plants, animals, and microbes in that they lack chlorophyll, which prevents them from utilizing sunlight to produce energy. Plants, animals, and microbes do not belong in the same kingdom as fungi, which is classed as a separate kingdom. More than 1.5 million fungus species are known to exist. Given that roughly 7 percent of all fungi have been described, the true number of fungal species is unknown. The Latin word fungus, meaning "mushroom," is the root of the English term "fungus."

Fungi can be found in nearly every environment on Earth where there is moisture, including in soil, on plants and even inside animals' bodies (such as humans). Fungal spores are everywhere throughout the environment; some can live for long periods without a host (known as saprobes). Most fungi do not cause disease; however, some species can cause disease in humans or other organisms.

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Control and Preventions for Communicable Diseases

Bacterial and fungal illnesses are both examples of communicable diseases. Direct touch with an infected individual, droplets of bodily fluids, or contact with contaminated objects are all ways in which they might be transmitted.

Here are some ways to prevent communicable diseases−

Use an alcohol-based hand sanitizer or soap and water to clean your hands frequently. You can use an alcohol-based hand sanitizer that contains at least 60% alcohol if you don't have access to soap and water.

While sniffling or hacking, cover your mouth and nose. Use a tissue or your elbow rather than your fingers when touching your face. Throw used tissues in the trash immediately after use and wash hands after handling them.

Maintain a safe distance from sick people. When possible, avoid crowds where people are likely to spread germs (for example, subways during the flu season).

Disinfect surfaces that may be contaminated by viruses or bacteria, such as doorknobs, telephones and keyboards. Use bleach solutions or other disinfectants according to the label directions.


There are many different diseases that humans can get. Some are caused by viruses, bacteria, or other microorganisms. Others are caused by genetic defects or problems. Still others are caused by environmental factors, such as exposure to toxic substances. The best way to protect yourself from getting a disease is to practice good hygiene, eat a healthy diet, and avoid exposure to harmful substances.


1. What is the most common disease in the world?

The most common disease in the world is diarrhea. Diarrhea is a general term for loose stools that occur more than four times in one day or last for more than three days. It is caused by any number of bacterial, viral, fungal and parasitic organisms that enter the body through the mouth and infect the intestines.

The most common viruses that cause diarrhea include rotavirus and norovirus. Other bacterial causes include Escherichia coli (E. coli) and Shigella species, while protozoans like Entamoeba histolytica may also lead to this condition.

2. What are the symptoms of human diseases?

The symptoms of a disease are the indications that someone has a disease. They can be physical or mental, but they must occur together for a diagnosis to be made.

3. What are the types of human diseases?

Human diseases come in many forms, including bacterial, viral and fungal infections and autoimmune disorders (when your immune system attacks your body). Infectious diseases are caused by microorganisms such as bacteria, viruses and fungi. Non-communicable diseases include cancer and heart disease. Autoimmune disorders occur when your immune system mistakenly attacks your own body's tissues.

4. Why is it important to wash your hands regularly?

It is very important that you keep your hands clean because you do not want to pass germs from your hands to other parts of your body or other people's bodies. Washing your hands often with soap and warm water will help prevent infections from spreading.

5. What is HIV/AIDS?

The virus that causes AIDS is known as HIV. If HIV severely weakens your immune system, you have Acquired Immune Deficiency Syndrome (AIDS), which implies that you cannot fight against infections and diseases.

Updated on 13-Oct-2022 11:19:47