Human Health and Disease

Introduction

A total physical, moral, emotional and social well-being condition is health. Significantly impact health like genetic disorders, certain infections, and lifestyle that you can learn in detail with human health and disease study material.

To achieve good health, it is necessary to be aware of diseases and their effects on various body functions, be vaccinated against infectious diseases, dispose of waste properly, control vectors, and maintain sanitary water and food resources.

Disease: A condition in which an organism’s activity is compromised, mostly with negative consequences and symptoms, is termed a disease. 

Types of diseases

1. Congenital diseases are illnesses that affect people from the moment they are born.
2. Acquired diseases – These develop after birth and continue throughout one’s life. Acquired diseases are divided into two categories: 

• Communicable diseases: Infectious or contagious diseases can be spread from a sick person to a healthy person via infectious agents. Examples – Malaria, Measles, etc. 
• Non-infectious or non-communicable diseases: Non-infectious diseases cannot be spread from an infected person to a healthy person. Example – Cancer

Some Common Infectious Diseases in Human beings 

Let’s have a look at common diseases with human health and disease study material:

Bacterial Disease

Typhoid 

• Salmonella typhi is the pathogen responsible
• It enters the small intestines through food and water and travels blood to other body parts
• The most common symptoms are fever of 39- 40 degrees Celsius, weakness, nausea, vomiting, diarrhoea, and a general lack of appetite
• To confirm the disorder, Widal testing is performed

Pneumonia 

• Streptococcus pneumoniae and Haemophilus influenza are the two pathogens
• Inhaled aerosols from an infected person can spread the disease. Sharing equipment and utensils with an infected person are not recommended
• Alveoli in the lungs are infected. Respiratory issues result from fluid buildup in the alveoli. Other symptoms are fever, chills, cough with phlegm or pus and a headache
• Lips and nails turn grey to bluish in the most severe cases

Viral Diseases

Common cold

• Rhinoviruses are the pathogens that cause the common cold
• Droplets arising from a cough or sneeze can be inhaled through infected objects
• Symptoms can persist from three to seven days, such as runny nose, sore throat, hoarse voice, cough, and exhaustion

Disease caused by Protozoans

Malaria

• Malaria is caused by Plasmodium (P. vivax, P. malariae, P. ovale. and P. falciparum)
• Biting of a female Anopheles mosquito is the method of transmission
• Hemozoin produces chills and a high fever lasting three to four days
• The primary host is a female Anopheles mosquito, while the secondary host is a human

Plasmodium life cycle in Humans

• Female Anopheles mosquito bite transmits Plasmodium sporozoites, the disease-causing stage of the parasite
• Sporozoites enter the liver cells from the blood and multiply there
• The parasites enter the bloodstream by ruptured liver cells and infect the RBCs as they increase, causing their release
• The release of hemozoin causes the recurrence of chills and fevers within three to four days is linked to the rupture

Plasmodium life cycle in Female Anopheles mosquito:

• Female Anopheles mosquitoes suck the blood of an infected human host and receive the RBCs, which include gametocytes, from the bloodstream
• In the mosquito’s stomach wall, the gametes grow and combine to produce a zygote
• To become sporozoites, the zygote undergoes further development
• When a female Anopheles mosquito bites a healthy person, the sporozoites in her saliva are injected into the victim’s blood

Amoebic dysentery

• The human large intestine is home to the pathogen Entamoeba histolytica
• Using mechanical transporters, house flies spread parasites from an infected person’s faeces to food and water, causing contamination
• All symptoms include constipation, cramping, blood clots in the stool, and loose, mucus-filled stools

Diseases caused by helminths

Ascariasis

• Ascaris is the pathogen
• Parasitic eggs can be found in soil, water, plants, and fruits that faeces have polluted
• Pain, fever, anaemia, digestive tract obstruction, and internal bleeding are symptoms

Elephantiasis

• Wuchereria is the pathogen (W. bancrofti & W. Malaysia)
• The bite of a female Culex mosquito transmits the disease
• A worm that lives in lymphatic vessels causes chronic inflammation of the organs. People may suffer from deformities in their legs and genitals

Fungal diseases

Ringworm

• Microsporum, Trichophyton, and Epidermophyton are the primary pathogens
• Using an infected person’s towels, clothes, comb, etc., can spread the disease
• Dry, scaly lesions appear on different body areas, including the skin, nails, and scalp

Disease Prevention and Control

• Maintain a clean and sanitary body
• Proper waste and excreta disposal
• Please keep away from people who have been infected, and their belongings
• Avoid water stagnation
• Consider introducing larvivorous fish like Gambusia into ponds
• For mosquitoes, wire mesh should be installed on doors and windows

Immunity

The ability of host cells to combat pathogens through the immune system is called immunity. Immunity consists of two components:

Innate Immunity

At birth, the body is equipped with various non-specific defence mechanisms that prevent foreign agents from entering the body. There are four types of barriers in this system.

• Skin mucus coating of the epithelium lining the respiratory, digestive, and urogenital tracts is a physical barrier
• The acid in the stomach and saliva in the mouth form a physiological barrier
• Leucocytes, neutrophils, and monocytes from the cellular border
• Infected cells produce interferon, a protein that acts as a cytokine barrier

Acquired Immunity

A person’s acquired immunity is a kind of immunity that develops over time and is pathogen-specific

• First contact with a pathogen elicits a low-intensity immune response
• A subsequent illness triggers a secondary or amnestic reaction because the body remembers the earlier answer
• B-lymphocytes produce antibodies in response to foreign antigens

Antibody 

• H2L2 Antibodies (Y-shaped protein molecules with four peptide chains; two light and two heavy) are the most common kind of antibody
• Humans have five different immunoglobulins, including IgG, IgM, IgD, IgA, and IgE antibodies
• The placenta transmits IgG to a developing foetus
• A high concentration of IgA may be seen in colostrum, a yellowish fluid
• The allergic response involves the immunoglobulin E (IgE)

Allergy 

• An overreaction of the immune system characterises allergies to specific environmental antigens. Allergens are substances to which an immunological reaction is elicited
• IgE-type antibodies are generated as a result
• Mast cells secrete substances including histamine and serotonin, which cause allergy

Immune System Diseases

• Lymphoid tissues, cells, and soluble chemicals like antibodies make up the human immune system
• The genesis, maturation, and proliferation of lymphocytes occur in lymphoid organs. Bone marrow and the thymus are two of the body’s primary lymphoid organs
• Lymphocytes move to secondary lymphoid tissues during maturation, such as spleen and lymph nodes and tonsils and Peyer’s patches of the small intestine and appendix. As a result, lymphocytes can engage with antigens at those locations
• A lymphoid tissue known as mucosal-associated lymphoid tissue (MALT) is found in the respiratory, digestive, and urogenital tract lining. It accounts for half of the human body’s lymphoid tissues

AIDS (Acquired Immunodeficiency Syndrome)

• AIDS is an immune system disease.
• The retrovirus with an RNA genome, HIV (Human Immunodeficiency Virus), is responsible
• In the United States, the first case of AIDS was reported (1981)
• Enzyme-linked immunosorbent assay (ELISA), PCR-Test, western blotting, etc., are some of the tests used to diagnose AIDS

Modalities of Communication:

(a) Having sex with an infected individual.

(b) Contaminated blood may be transfused.

1. Shared use of contaminated needles.
2. Through the placenta, from the infected woman to the kid.

Cancer

Cancer results from an abnormal and uncontrolled growth of cells, which results in tumours (masses of cells).

Benign tumours and malignant tumours are the two types of tumours that exist.

Benign Tumour

• It affects the area where it started and did not spread to other body sections
• It is not harmful to the human body

Malignant Tumour

• It spreads and infiltrates the tissues immediately and is the most dangerous

Detection and Diagnosis of Cancer

• Biopsy and histological examinations can detect increased cell counts using blood and bone marrow tests
• CT (Computerised tomography) scan and MRI (Magnetic resonance imaging) (Magnetic Resonance Imaging)
• The use of anti-cancer antibody therapy
• To detect cancer-related genes, molecular biology techniques are used

Conclusion 

Various bacterial, viral, and so forth diseases are present in our environment, directly affecting human health. Ailments can transform the average fitness of a person into harmful conditions. They can either be infectious or non-communicable and contagious or acquired. Each disorder has its distinctive symptoms, like cold, headache, and so forth. Diseases can be caused by different viruses, bacteria, protozoa, helminths, and fungi. Infections caused by various pathogens differently harm the body. We learned about different types of diseases with their sources in this article.