2. Pathology
• Scientific study of disease
• Patho- suffering, Logo- Science
• It is concerned with
• cause or etiology of diseases and
• pathogenesis, the Manner in which a disease develops
• Structural and functional changes brought about by the disease
• Final effects on the body
3. • The invasion or colonization of the body by the pathogenic
microorganism
• In other words, infection can be defined as the presence of a
particular type of microorganism in a part of body where it is not
normally found is called infection
Infection
4. Disease
• Disease occurs when an infection results in any change from a state of Health
• It is an abnormal state in which a part or all of the body is not properly adjusted or
incapable of performing in normal function
• An infection may exist in the absence of detectable disease
• Ex: A body may be infected with virus that causes AIDS, but there may be no
symptoms of the disease
5. TYPES OF INFECTION
• 1. PRIMARY INFECTION
• 2. SECONDARY INFECTION
• 3. SUBCLINICAL INFECTION OR INAPPARENT INFECTION
7. TYPES OF INFECTION
• PRIMARY INFECTION: It is an acute infection that causes intial illness
• SECONDARY INFECTION: It is caused by an opportunistic pathogens after the
primary infection, that has weekened the body’s defences
• Secondary infection of skin is very common and sometimes dangerous than primary
infection
• Ex.
• Pneumocystis pneumonia in AIDS patient
• Streptococcal bronchopneumonia in Influenza patients
8. Subclinical infection or Inapparent infection
• Subclinical infection is one that doesn’t cause any noticeable illness
• Example: Poliovirus and Hep- A- Virus can be carried by people who
never develop the illness
• Chronic Disease:
• It develops more slowly and but disease is likely to be continual or
recurrent for long periods
• Ex. Infectious mononucleosis, Hep B, TB
• Acute Disease:
• Develops rapidly but lasts only a short time
9. • Sub - acute Disease:
A disease that is intermediate between acute and chronic
Ex. Sclerosing pan encephalitis, a rare brain disease characterized
by diminished Intellectual function
Acute infection:
• An Infection characterized by sudden onset, rapid progression and
often with severe symptoms
Chronic Infection:
• An Infection characterized by delayed onset and slow progression
Cross infection:
• Already suffering from a disease and acquire new disease from another
host or another external sources
10. Endogenous Infection/Disease:
Type or kind of infection or disease originates within the body
Endo – Inside, Genous – Type or Kind
Ex. Metabolic disorders, Congenital ( in born) abnormalities, Tumors, etc.,
Exogenous Disease:
• Kind of disease or infection originates out side the body Ex. Chemical agents,
Electrical shock, trauma
Nosocomial infection:
• Hospital acquired infection
• Infection transmitted by Health care workers
Iatrogenic Infection:
Physician induced infection during therapeutic or investigative procedure
11. Congenital disease:
Disease develops due to hereditary disorder, may be inborn Ex. Leucoderma,
Heart diseases, etc.,
Teratogenic infection:
• Infection due to teratogens, an agent that can disturb the development of
an embryo or fetus
• It can cause birth defects in child ex. Radiation, Maternal infection,
chemicals or drugs
Laboratory infection:
• Infection acquired through lab or lab related activities regardless it may be
symptomatic or asymptomatic
12. Latent Infection:
After following an infection the pathogen remains in tissues in a hidden
or latent form which produce clinical disease when the host resistance is
lowered
