Common Human Diseases

Diseases can be defined as ‘disorders in the physical, physiological, psychological, or social state of a person caused by nutritional deficiency, physiological disorder, genetic disorder, pathogen, or any other reason. They may be caused by various reasons are factors. Some diseases harm only individuals and some impact the community. They can be classified on the basis of various factors, here we discuss them.

Classification of Diseases 

Diseases may be classified as Congenital diseases and Acquired diseases.

Congenital disease – These diseases are present from birth (e.g. hole in the heart in infants). They are caused by some genetic abnormalities or metabolic disorders or malfunctioning of an organ.

Acquired diseases These diseases may occur after birth caused by many factors. Acquired diseases may be classified as

  • Infectious diseases: This type of disease can be transmitted from a diseased person to a healthy person e.g. measles.
  • Degenerative diseases: This type of disease is caused by the malfunction of some vital organs of the body e.g. heart failure or kidney failure.
  • Deficiency diseases: These are caused by nutritional deficiencies like minerals or vitamins in the diet e.g. anemia (Fe), Beri- Beri (vitamin B).
  • Cancer

Deficiency diseases

Diseases in humans due to deficiency of vitamins are listed below:

vitamin Sources Deficiency symptom
Fat-soluble vitamins  
Vitamin A( Retinol) Milk, cheese, butter, eggs cod liver oil, spinach, etc. Night blindness. Cannot see in dim light(night blindness)
Vitamin D (Calciferol) Milk, cheese egg yolk, cod liver oil, sunlight. Rickets in children Failure of growing bones, softening of bones seems bow legs, pigeon chest
Vitamin E (Tocopherol) Grains, vegetable oil, green leafy vegetables, etc. Problems in the reproduction of males and females Sterility in males, miscarriage, or other problems in females.
Vitamin K (phylloquinone) Green leafy vegetables, soybeans,  tomatoes. Hemorrhage, (Don’t clot of blood on average time ) Delayed blood clotting
Water-soluble vitamins
Vitamin B1 (Thiamine) Yeast, milk, cheese, leafy vegetables, meat, etc. Beriberi Pain in hands and feet. Oedema.
Vitamin B2 (Riboflavin) Milk, liver whole grains, eggs, peas, etc. Ariboflavinosis cracks in the skin at the corners of the mouth, fissures of the lips, etc.
Vitamin B3 (Niacin) Fish, eggs, legumes whole grains, peanuts, beans, etc. Pellagra Dermatitis, diarrhea, dementia
Vitamin B12 (cyanocobalamin) cheese; milk; Liver; fish; etc. Pernicious anemia Paleness of skin, the problem in breathing.
Vitamin C (Ascorbic acid) Amla, cabbage, lemon, orange, and other citrus fruits. Scurvy Bleeding Gums, pain in joints, weakness

Diseases caused by a deficiency of minerals

Minerals play a vital role in our lives, as they help in growth, circulation and so many functions. The deficiency of these minerals also causes diseases.

List of some common human diseases caused by mineral deficiencies:

Minerals Functions Food sources Deficiency
Calcium Formation of bones and teeth, necessary for nerves and muscles. Milk, dairy products, green leafy vegetable cereals, etc. Rickets, Osteomalacia, Degradation of teeth
Iron Formation of hemoglobin Green, vegetables, spinach, jaggery, etc. Anemia, loss of appetite
Phosphorus Formation of bones and teeth Milk; Cereals, Green leafy vegetables, Nuts, Bajra (millets), etc. Softening of bones
Iodine Metabolic control of thyroxine hormone, mental ability Iodized salt, seafood, green leafy vegetables, etc. Enlargement of the thyroid gland called Goitre
Sodium and Potassium Maintenance of water balance, and conduction of nerve impulses. Common salt, eggs, spinach; pulses, etc. High blood pressure. Balance disturbance.

PEM caused by Malnutrition

Protein-energy malnutrition (PEM) A number of children in the age group of 1-5 years suffering PEM, is caused by two reasons:

  • Lack of proteins or carbohydrates or both in the diet.
  • Excess intake of carbohydrates rather than proteins.
  • It causes two diseases Marasmus and Kwashiorkor

PEM malnutrition diseases

Cancer: This is an abnormal, uncontrolled, and unwanted growth of cells. e.g. Liver cirrhosis, Brain tumors, etc. (I’ll try to post a separate blog on ‘Cancer’)

Acquired diseases can be studied under two categories

  • Communicable diseases These diseases are transmitted from an infected person to a healthy person.
  • Non-communicable diseases These diseases do not transmit from an affected person to a healthy person

Modes of communicable diseases:

Modes by which the Spread of Communicable Diseases takes place-

Communicable diseases can spread from the infected person to a healthy person in the following ways.

Direct transmission

The pathogens of diseases infect a healthy person directly without an intermediate agent. It can take place by various means such as

  • Direct contact between the infected person and the healthy person: Diseases like smallpox, chickenpox, syphilis, and gonorrhea spread via direct contact.
  • Droplet infection: The infected person’s tiny droplets of mucous by coughing, sneezing, or spitting. These droplets may contain the pathogen. By inhaling the air containing the droplets, a healthy person may get the infection. Diseases like the common cold, pneumonia, influenza, measles, tuberculosis, and whooping cough spread through droplet infection.
  • Contact with soil: contaminated soil with disease-causing organisms or viruses.
  • Animal bite: Viruses of rabies are introduced through the wound caused by the bite of rabies animals, especially dogs.

Indirect Transmission

certain diseases in humans are caused by some pathogens that come indirectly into the body by some intermediate carrier. For example- Vectors such as houseflies, mosquitoes, and cockroaches

Some Common human communicable diseases

Common human diseases caused by viruses

  • Chickenpox-
    • Pathogen: Chickenpox virus (varicella)
    • Incubation period: 12-20 days
    • Symptoms- fever, headache, loss of appetite, Dark red colored rash on the back and chest which spreads on the whole body.
    • Prevention: Vaccine

  • Measles
    • Type of infectious agent: Virus
    • Prevention factors: MMR vaccine
    • symptom- Common cold, small white patches appear in the mouth and throat, the appearance of rashes on the body.
    • Prevention- The patient should be kept in isolation, Cleanliness must be maintained, and Antibiotics check only the secondary infections which can easily recur.
  • Poliomyelitis-
    • Pathogen: Polio Virus
    • Mode of transmission: Viruses enter the body through contaminated food or water.
    • Incubation period: 7-14 days
    • Symptoms- It damages the brain and nerves and causes infantile paralysis, and stiffness of the neck, fever, loss of head support can be found.
    • Prevention- Polio vaccine drop (oral polio vaccine, OPV) is given to children at certain intervals.

*** The Pulse polio program is organized in our country by the government to give polio vaccine to children.

  • Rabies (hydrophobia)-
    • Pathogen: Rabies virus
    • Mode of Transmission: Biting by a dog carrying the rabies virus.
    • Symptoms- Severe headache and high fever, Painful contraction found in muscles of throat and chest, fear of water lead to death.
    • Prevention- Compulsory immunization of dogs, the killing of rabid animals, Anti-rabies injections, or oral doses must give to the person bitten by a rabid animal.

  • Hepatitis-
    • Pathogen: Hepatitis B virus
    • Mode of Transmission: Mainly transmits through contaminated water.
    • Incubation Period: Generally, 15-160 days.
    • Symptoms- Pain in the body, Loss of appetite and nausea, Eyes and skin become yellowish, urine deep yellow in color (due to bile pigments). Enlargement in the liver was found.
    • Prevention and Cure- Hepatitis B vaccine should be given to an infected person, through simple and healthy food that must not be oily.

  • Influenza (flu)-
    • Pathogen– Virus
    • Symptoms– fever normally 100 ° F to 103° F in adults and even higher in children with infection in the respiratory tract. Symptoms such as cough, sore throat, running nose, headache, pain in the muscles, and extreme fatigue.
    • Prevention and cure– The influenza vaccine should be given to those who are at high risk for complications with chronic diseases of the heart, lungs, or kidneys, diabetes, or severe forms of anemia. Advice from the doctor should be taken.

  • Dengue- Dengue is an acute fever caused by the virus. It is of two types:
    • Dengue fever– main characteristics of this fever are sudden high fever, severe headache, and pain in the muscles, and joints.
    • Dengue hemorrhagic fever– It is an acute infectious viral disease. It is an advanced stage of dengue fever. It is characterized by fever during the initial phase and other symptoms like headache, pain in the eye, joint pain, and muscle pain, followed by signs of bleeding, red tiny spots on the skin, and bleeding from the nose and gums
    • Pathogen– a bite of an infected Aedes Aegypti mosquito

ades mosquito causes very common disease Dengue

ades egypt mosquito causing Dengue

  • Incubation period– After a bite of a mosquito carrying the dengue virus the symptoms start on average 4 to 6 days, with a range of 3 to 14 days.
    • Symptoms- Sudden onset of high fever, generally 104-105 °F (40 °C), which may last 4-5 days. Severe headache mostly in the forehead, Nausea, or vomiting. After all, if treatment is not done, then Dengue hemorrhagic fever occurs. In hemorrhagic dengue rashes on the skin, Bleeding from the nose, mouth, or internal organs, Black stools due to internal bleeding, Excessive thirst, Pale, cold skin, and weakness are found.
    • Prevention- Avoid water stagnation for more than 72 hours by which the breeding of mosquitoes can be stopped there. Use mosquito repellents and long-sleeved clothes to curtail exposure. Use mosquito nets, also during the daytime. After all these preventions the infected person should go to a medical consultancy.

Diseases Caused by Bacteria 

  • Pathogen-Mycobacterium tuberculosis
  • Transmission through infection spreads from person to person by various mediums like -air, cough, and sneezing of the infected person.
  • Incubation period- It takes two weeks to ten weeks in an infected person the bacteria show its effect.
  • Symptom – The infected person shows various symptoms like persistent fever and coughing, Chest pain, and blood patches found with the sputum. The weakness of a person.
    • Prevention and Cure-
      • The patient should be isolated to avoid the spread of infection.
      • BCG vaccination should be given to every child as a preventive measure. The place where a person lives should be airy, neat, and with clean surroundings.
      • Medicines such as antibiotics should be given with the consultation of Doctors.
  • Pathogen: Bacterium Salmonella typhi
  • Mode of transmission: Transmit through contaminated food and water.
  • Incubation period: About 1-3 weeks
  • Symptoms- It has symptoms including high fever, headache, stomach pain, weakness, vomiting, and loose stools.
    • Prevention and Cure-
      • At the time of eating and drinking, everyone should care about hygiene.
      • Avoid taking exposed food and drinks as they may be contaminated.
      • Proper sanitation and cleanliness should be maintained regularly.
      • Immediate treatment with the consultation of a doctor.
  • Pathogen – Bacterium Vibrio cholera
  • Mode of transmission: Contaminated food and water.
  • Symptoms- Acute diarrhea, watery stool, Muscular cramps, and Loss of minerals can lead to death.
    • Prevention and cure-
      • vaccination should be given for cholera, Electrolytes (Na, K, sugar) dissolved in water should be given to the patient to check or avoid dehydration.
      • It is available on the market as an ORS–oral hydration solution for dehydration.
      • proper sanitation and careful disposal of waste of an infected person.
      • medical treatment.
vibrio cholerae- vector of The disease cholera

vibrio cholerae- vector of The disease cholera

  • Pathogen: Rod-shaped bacterium Cornybacterium diphthereae
  • Mode of Transmission: Transmits through the air, droplet infection.
  • Symptoms-Fever, Sore throat, restless feeling, problem with breathing, air passage may get disturbed and lead to death.
    • Prevention and cure-
      • Medical treatment should be given to the patient immediately.
      • DPT vaccine is available and should be introduced to children.
      • A neat and clean environment should be provided.
Leprosy- (Hansen’s disease)
  • Pathogen: The pathogen of leprosy is the bacterium Mycobacterium leprae.
  • Mode of transmission: It transmits through prolonged contact with an infected person. So it is not very contagious, a long period of contact can spread the infection.
  • Symptoms- it mainly affects the skin as changes skin color and reduces sense in skin, hands, and feet. It affects the eyes, nose, and also peripheral nerves.
    • Prevention and Cure– Immediate treatment can avoid many disabilities so medical treatment should be provided to the person as soon as possible.

There are some diseases found caused by pathogens other than viruses and bacteria, like protozoans, and worms.

Diseases caused by protozoans

  • Pathogen- The pathogen responsible for malaria is a different species of Plasmodium. five species of plasmodium infect humans. P. Falciparum causes most of the deaths by malaria. P. vivex, P.ovale, P. malaria cause mild malaria.
  • Mode of transmission: It transmits through the bite of female Anopheles mosquitoes. Malaria has two phases during its infective period, the first phase in mosquitoes and the second and final phase of infection in humans through plasmodium.
  • Symptoms- chilliness and shivering followed by the fever which repeats itself after sweating and being normal for a few hours. The patient becomes weak which leads to anemia, if proper treatment is not given to the patient, the secondary complication may be fatal as it can last to the death of the person.
transmission of the disease malaria
  • Prevention and cure-
    • Use of mosquito net and mosquito repellents.
    • The sprinkling of kerosene oil in ditches or other open spaces where water gets collected should be done.
    • Treatment should be started on time.
    • Treatment- Antimalarial medication.
Amoebiasis (Amoebic dysentery)
  • Pathogen: caused by amoeba Entamoeba histolytica
  • Mode of transmission: Transmits through Contaminated food and water.
  • Symptoms- It shows very common symptoms, or maybe no symptoms, or severe symptoms like abdominal pain, diarrhea, or bloody diarrhea.
    • Prevention and Cure-Sanitation should be maintained properly, Vegetables and fruits must be properly washed before eating. Antibiotics may be given to the patients with a consult from a doctor.

Diseases caused by worms (helminths)

  • Pathogen: Filarial worm (roundworm), various types of filarial worms are found, are divided into three groups –
  • Lymphatic filariasis- Wuchereria bancrofti
  • Subcutaneous filariasis- loa-loa
  • Serous cavity filariasis- Mansonella perstans
  • elephantiasis– thickening of the skin and underlying tissues- shows edema.
Common Human Diseases and Pathogenes


  • Mode of transmission: Spreads through bites of mosquitoes – Aedes and Culex, and other blood-sucking insects.
  • Symptoms- Mild fever, Collection of endothelial cells and metabolites in the wall of lymph vessels,
  • Prevention and cure- Neat clean environment, mosquito repellent, dirty places should be cleaned. A sprinkling of chemicals for killing mosquitoes and flies. Drugs should be administered during proper medication.

*** We will discuss in detail Diseases like AIDS and other STDs in another blog. Thank you

You can also read: Viruses

The Viruses- Classification, Structure and Diseases

Thank you 🙂 

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