Ritu's Biology Hub

Hello to all my readers! Here, I have enlisted some more important key terms which are crucial under this topic of epidemiology. This is a continuation of the previous part. Please read that first to get a better understanding of the content. Happy reading 🙂

Continue from Part 1

Incubation period – Period between pathogen entry into the host body and the expression of first signs and symptoms. The pathogen is spreading inside the body but has not reached a sufficient level to cause clinical manifestation, which depends on several factors such as the microbe involved, virulence, no.of infecting microbial cells, resistance of the host etc.

Prodromal period – Period in which there is onset of signs and symptoms but they are not yet specific enough to make a diagnosis. Characterized by early, mild symptoms – aches and malaise

Period of illness – Phase in which the disease is most severe and has characteristic signs and symptoms like fever, chills, myalgia, pharyngitis, photophobia, GI disturbances etc.

Period of decline – Phase when signs and symptoms subside

Convalescence period – Person regains strength and the body returns to its pre-diseased state ie., recovery has occurred

Nosocomial infections – Infections which do not show any evidence of being present or incubating at the time of admission to a hospital. It is acquired as a result of hospital stay

Predisposing factor – These are the various factors that make a person more susceptible to a disease than another person and may alter the course of a disease

Local infections – Infections in which the invading microbes are limited to a relatively small area of the body

Systemic infections – Infections in which the microbes or their products are spread throughout the body via the blood or lymph. Example – measles

Mixed infections – Infections in which several different types of microorganisms infect and grow simultaneously at the infection site

Focal infections – Infections in which the agents of local infection enter the bloodstream or lymphatic system and spread to other specific sites in the body giving rise to infections at these loactions

Sepsis – Toxic inflammatory conditions arising from spread of microbes or their toxin from a focus of infection

Septicaemia – Systemic infection arising from multiplication of pathogens in blood

Primary infections – Acute infection that causes the initial illness

Secondary infections – Caused by an opportunistic pathogen after the primary infection has weakened the body’s defense mechanism

Subclinical / inapparent infection – Infection that does not cause noticeable illness

Acute disease – Infection that develops rapidly but lasts for a short time

Chronic disease – Develops more slowly, body’s reactions may be less severe but the disease is likely to be continued or recurrent for a long time. Example – Tuberculosis, Hepatitis B

Herd immunity – When maximum number of people in a population are vaccinated against a certain disease providing a long-lasting effect, that acts as a barrier to the infection from spreading to the non-vaccinated people.  Thus, the non-vaccinated people automatically develop resistance to such diseases. This is called as herd immunity

Communicable disease – One that spreads from one person to another either directly or indirectly. Example – Chicken pox, Measles, Typhoid fever, Tuberculosis

Non-communicable disease – One that does not spread from one person to another person. Example – Autoimmune disorders, Neurodegenerative disorders, Cancer, Diabetes, Endocrine disorders