Common Human Diseases

The word disease implies that dis-ease (not easy). In other words malfunctioning or improper functioning of various body parts like genetic disorder, hormonal imbalance, malfunctioning of immune system of body are some factors which affects the human health or it is a condition that prevents the body or mind from working normally.

Types of Diseases: On the basis of its nature, character and causes of its spreadness is of two types:

1. Congenital Disease is the diseases which are present since birth. These are caused due to genetic abnormality or due to metabolic disorders or malfunctioning of any organ. They are basically permanent, generally not easily curable and may be inherited to the children like Harelip, Cleft Palate, Club foot etc. Also due to imbalance in the chromosomes the appearance of Mongalism, to born the blue baby due to cardiac disorder etc are also some examples of it.

2. Acquired Disease is those defects or disorders which are not present by birth but appear due to the various causes and factors. These may be further categorized into following heads:

(i) Communicable or infectious diseasesThese are caused by a variety of pathogenic viruses, bacteria, protozoa, fungi and worms. The pathogens are generally carried with the help of a vector.

(ii) Non-communicable or non-infectious or degenerative diseasesThese occur due to the malfunctioning of some organ or organ system in the body. It may be of various types like Deficiency diseasesThese occur due to the deficiency of some nutrients, minerals or vitamins, Cancerous diseasesAllergy, Genetic diseases.

Diseases Spread through Blood Transfusion

AIDS (Acquired Immuno Deficiency Syndrome):It destroys immune systemof the body & is caused by the Human Immuno deficiency Virus (HIV).There are two types of HIV namely HIV-1and HIV-2The most common virus currently associated with AIDS is HIV-1. A virus found in the blood of wild African green monkey called the Simian Immuno deficiency Virus(SIV) is similar to HIV-2. HIV is a retrovirus. It can synthesize DNA from RNA. The major cell infected by HIV is the helper T-Iymphocyte that bears the CD-4 receptor site. HIV progressively destroys T-Iymphocytes. The patient occasionally will suffer from swollen lymph nodes, mild prolonged fever, diarrhoea or other non-specific symptoms.


Cancer: They are characterized by the uncontrolled growth and division of cells which leads to a mass of cells known as neoplasm. Abnormal and persistent cell division localized in a particular region is called benign tumor.

Gout: It results from accumulation of uric acid crystals in the synovial joints. It is a disease associated with an inborn error of uric acid metabolism that increases production or interferes with the excretion of uric acid.

Haemophilia is called bleeder’s disease. It is a disorder which is sex-linked and is a recessive condition. In a patient of haemophilia, blood clotting is deficient.

Haemophilia A, is characterized by lack of anti- haemophilia globulin factor VIII. About four-fifths of the cases of haemophilia are of this type.

Haemophilia B or Christmas disease results from a defect in plasma thromboplastic component.

Hepatitis : It is a viral disease, causes hepatic anorexia resulting in liver damage (liver cancer) or jaundice. It is transmitted by the faecal-oral route. Children and young adults are susceptible to it and no vaccines are acceptable.

Diseases caused by Viruses

Name of diseaseCaused byParts of body affectedMethod of spreadType of Vaccination
InfluenzaA myxovirus (RNA virus)Respiratory passages: epithelial lining of trachea and bronchi.Droplet InfectionKilled virus
Common coldLarge variety of viruses, commonly rhino-virus (RNA Virus)Respiratory passagesDroplet InfectionIntramuscular injection.
SmallpoxVariola virus (DNA virus)Respiratory passages, then skinDroplet Infection (Wounds in skin)Living atteneuated virus applied by scratching skin, no longer carried
ChickenpoxVaricella- zosterBlistering Skin rashAir-borne dropletsLiving attenuated virus
MumpsA paramyxovirus (RNA virus)Respiratory passages, infection via blood, salivary glands, testes in adult malesDroplet infectionLiving attenuated virus
MeaslesA paramyxovirus (RNA virus)Respiratory passages, spreading to skin and intestines.Droplet infectionLiving attenuated virus
German measles (Rubella)Rubella virusRespiratory passages, lymph nodes in neck, eyes and skin.Droplet infectionLiving attenuated virus, more essential for girls because disease causes complication in pregnancy.
Poliomyelitis (polio)Poliovirus (RNA Virus)Pharynx and intestines, then blood; occasionally motor neurons in spinal cord, paralysis may occur.Droplet infection or via human faecesLiving attenuated virus given orally
Yellow feverAn arbovirus i.e arthropod-borne virus (RNA Virus)Lining of blood vessels and liverVector- arthropods e.g ticks, mosquitoesLiving attenuated virus
AIDSRetrovirus (RNA virus)Skin CancerSexual intercourse homo- and hetrosexualsNot available
Ebola haemorrhagic feverEbola Virus disease (EVD)Fatal Illness in Humans, FeverIt is transmitted to people from wild animals and spreads in the human population through human-to-human transmission.No licensed Ebola vaccine is available
Zika diseaseZika Virus (mosquito borne disease)Causes mild illness in the people like dengue, yellow feverBasically Infection in pregnant women is linked to abnormally small heads in their babies.No vaccine available

Diseases caused by Bacteria

Name of disease Caused byParts of body affectedMethod of spreadType of vaccination or antibodies
DiphtheriaCorynebacterium diphtheriaUpper respiratory tract, mainly throat also toxin affects heart.Droplet infectionToxoid
Tuberculosis (TB)Mycobacterium tuberculosisMainly lungsDroplet infection, Drinking milk from infected cattle.BCG living attenuated bacteria. Antibiotics e.g. streptomycin.
Whooping cough (Pertussis)Bordetella pertussisUpper respiratory tract, inducing violent coughingDroplet infectionKilled bacteria
GonorrhoeaNeisseria gonorrhoeaeReproductive organs: mainly mucous membranes of urinogenital tract. Newborn infants may acquire serious eye infections if they pass through infected birth canal.Contagion by sexual contactAntibiotics, e.g. penicillin, streptomycin
SyphilisTreponema pallidumReproductive organs, then eyes, bones, joints, central nervous system, heart and skin.Contagion by sexual contactAntibiotics. e.g. penicillin
TetanusClostridium tetaniBlood.Toxin produced which affects motor nerves of spinal cord and hence muscles, causing lockjaw and spreading to the muscles.Wound infectionToxoid
CholeraVibrio choleraAlimentary canal: mainly small intestine.Faecal contamination(a) food – or water borne of material contaminated with faeces from infected person.(b) handling of contaminated Objects.(c) vector, e,g. flies moving from human faeces to food.Killed bacteria: short-lived protection and not always effective Antibiotics e.g. tetracyclines, chloramphenicol.
Typhoid feverSalmonella typhiAlimentary canal, then spreading to lymph and blood, lungs, bone marrow, spleen.Same as choleraKilled bacteria (TAB vaccine)
Bacterial dysenteryShigella dysenteriaeAlimentary canal, mainly ileum and colonSame as choleraNo vaccine.
Bacterial food poisoning (gastro enteritis or salmonellosis)Salmonella spp.Alimentary canalMainly foodborne meat from infected animals from poultry and pigs. Also via faecal contamination as choleraAntibiotic. e.g. tetracyclines.

Diseases Caused By Worms

DiseasePathogen responsible and its habitatMode of transmissionMain symptoms
Ancylostomiasis or ‘Hook-worm disease’Ancylostoma duobenale, small intestine (jejunum) of manTransmission from person to person, filariform larvae passed out in faeces, man picks up infection walking barefoot on faecally-contaminated soil.Dermatitis; reddish, severe anaemia; duodenal ulcer, constipation. Patient pale, face puffy with swelling of lower eyelids.
AscariasisAscaris Lumbricoides; small intestine (jejunum) of manTransmission from person to person, ripe eggs passed out in faeces, infection affected by swallowing ripe Ascaris eggs with raw vegetables.Larvae in lung cause pneumonia. May give rise to typhoid-like fever, causes protein and Vitamin A deficiencies resulting in protein-calorie malnutrition and night blindness respectively. Can cause appendicitis, jaundice.
Enterobiasis or ‘Pinworm disease’Enterobius vermicularis, caecum and vermiform appendixTransmission from one person to another by ingestion of eggs in contaminated food or drink.Eczematous condition round the anus, bed wetting at night, inflammation of vermiform appendix.
FilariasisWuchereria Bancrofti, lymphatic vessels and lymph nodes.Part of the life cycle in mosquito in which larvae develop and become infectious to man, with mosquito bite larvae deposited on skin which enter through puncture wound and reach lymphatic channelsElephantiasis i.e. enormous enlargement of certain parts such as that of leg, scrotum, penis, labia, clitoris, breast, forearm.

Diseases caused by Fungus

DiseasePathogen responsibleMode of transmissionMain symptoms
Ringworm (tinea)Microsporum, TrichophytonDirect contact from unbathed cats and dogs or objects handled by infected individualsContain one or more blistered areas on skin and scalp. Cause partial and temporary baldness in children.
Athlete’s footTrichophytonBad foot hygiene where skin remains warm and moist for long periods.Painful itching or burning sensation in the infected areas. Crack appears in the skin, mass of loose dead skin clings between toes.
Madura footMaurella MycetomiFungi gain entry through some minor injury to the skin.Produce a chronic, granulating infection of the lower extremities, affected part becomes enlarged and develops many deep sores, extensive bone destruction leading to crippling deformities.
Dhobie itchSeveral Different FungiDirect contact through Objects handled by infected person.A type of ringworm infection usually located in the groin and inner surfaces of thighs, red rash which itches intensely.