Human Diseases: Causes, Transmission, Diagnosis, and Treatment
Diseases Caused by External and Internal Factors
External Factors
Diseases caused by external factors include:
- Bacterial diseases
- Viral diseases
- Parasitic diseases (e.g., blindness)
Internal Factors
Diseases caused by internal factors include:
- Genetic defects
- Degenerative diseases (e.g., flu)
Modes of Disease Transmission
- Through inanimate objects
- Through the water we drink
- Through the ingestion of contaminated food
- Through the air
- Through vector transmission
Examples of Diseases Caused by Different Pathogens
Biological Pathogens
Example: Tetanus
Physical and Chemical Pathogens
Example: Deafness
Psychological, Social, and Cultural Pathogens
Examples: War, economic crisis
Infectious and Parasitic Diseases
Infectious Diseases
Infectious diseases are characterized by easy and fast transmission, caused by pathogens. The pathogens of such diseases are often viruses.
Parasitic Diseases
Parasites find favorable conditions in the host for nesting, development, multiplication, and virulence, so they may cause illness. Because parasites are well-adapted to their ways of life, they are difficult to destroy. They develop strategies to avoid the defense mechanisms of their hosts, and many have managed to become resistant to drugs and insecticides applied for control.
Clinical Picture (Phases of the Disease)
- Penetration of the microorganism
- Incubation period
- Evident symptoms of the disease
- Period of decline
- Period of convalescence
Examples of Diseases Caused by Different Agents
- Prions: Fatal familial insomnia
- Viruses: AIDS
- Bacteria: Listeriosis
- Fungi: Mycosis
- Parasites: Malaria, elephantiasis
New, Emerging, and Reemerging Diseases
New Diseases
Example: Yellow fever
Emerging Diseases
Emerging diseases are those newly discovered that cause serious health problems locally or internationally. Example: HIV/AIDS
Reemerging Diseases
Reemerging diseases are those allegedly controlled or virtually disappeared, returning as a threat. Examples: Tuberculosis, plague, cholera
Diagnostic Methods
Chemical Analysis
Involves taking a blood sample from a person to determine if they have a disease.
Biochemical Analysis
Determines the concentration of various chemicals found in the blood.
Genetic Analysis
DNA analysis of a person, usually from a blood sample.
Pathology
A medical specialty that deals with the study of cellular, tissue, and organ lesions.
Diagnostic Imaging
- Radiography: Takes images of any bone in the body.
- Scanner: Uses extremely low levels of X-rays.
- CT (Computerized Axial Tomography): Uses X-rays and a computer system to process images and, if necessary, create three-dimensional images of organs.
Disease Treatment
Pharmaceuticals
Drugs intended for use in humans or animals to prevent, treat, alleviate, or cure diseases and their symptoms.
Chemotherapy
A combination of drugs that must be administered periodically for a time to kill cancer cells.
Radiotherapy
A process consisting of energy associated with an electromagnetic wave. The radiation impacts cells, altering their DNA.
Psychotherapy
Promotes the achievement of changes or modifications in behavior.
Surgery
The practice that involves mechanical manipulation of anatomical structures for medical purposes.