305 week 7 disease intro

Disease

An alteration of homeostasis.

Pathophysiology

The study of altered physiological processes associated with disease.

Pathology

The study of disease in general.

Signs

Objective evidence of disease observed or measured during examination, such as pulse and blood pressure.

Symptoms

Subjective experiences reported by the patient, such as dizziness and nausea.

Syndrome

A recognizable pattern of signs and symptoms occurring together; it may have multiple causes.

Diagnostic investigations

Tests providing objective evidence of disease, including urinalysis, blood chemistry, electrocardiography, and radiography.

Diagnostic imaging techniques

Computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and nuclear medicine.

Other sources of diagnostic evidence

Biopsy samples, physical examination, medical history, family history, and medication history.

Prognosis

The predicted course and outcome of a disease, including chances of recovery, permanent loss of function, and survival.

Pathogenesis

How a disease begins and develops.

Stages of disease development

Exposure and entry → inoculation → incubation → prodromal period → illness → recovery.

Incubation period

No signs or symptoms

Prodromal period

The stage when nonspecific symptoms appear before characteristic signs and symptoms develop.

Illness stage

The stage when characteristic signs and symptoms of disease appear.

Acute disease

Has a rapid onset and short duration; examples include influenza, measles, and the common cold.

Chronic disease

Usually develops more slowly and persists for a long time; examples include arthritis, hypertension, and diabetes.

Terminal disease

A disease that will end in death.

Remission

Signs and symptoms subside.

Exacerbation

Signs and symptoms recur or increase in severity.

Relapse

A disease returns after a period of improvement, potentially weeks or months later.

Complication

A secondary disease or condition resulting from another disease; examples include kidney failure secondary to diabetes and anemia associated with leukemia.

Sequela

A lasting aftermath or consequence of a disease, such as paralysis following polio.

Mortality

A measure of deaths attributed to a disease.

Morbidity

The burden of disease, including the number of people affected, illness, disability, and reduced quality of life.

Comorbidity

The presence of another disease or condition that may affect the morbidity or mortality of a particular disease; it may also be a risk factor.

Prevalence

The number of existing cases in a specified population at a given time; useful for comparing population groups.

Incidence

The number of new cases in a specified population during a given time; useful for tracking changes in disease occurrence.

Etiology

The cause of a disease or infection.

Idiopathic disease

A disease whose cause is unknown.

Nosocomial disease

A disease acquired in a hospital or healthcare setting.

Iatrogenic disease

A disease or complication resulting from medical treatment or intervention.

Risk factors

Characteristics or exposures that predispose an individual to developing a disease.

Types of risk factors

Environmental, chemical, physiological, psychological, age-related, gender-related, lifestyle-related, and genetic factors.

Treatment of disease

Interventions intended to cure disease or reduce symptoms, including medications, surgery, exercise, nutrition, and physical therapy.

Palliative care

Care focused on reducing pain and minimizing symptoms rather than curing the disease.

Holistic medicine

Considers spiritual and psychological aspects in addition to other aspects of care.

Outbreak severity

Depends on virulence (severity or deadliness) and transmission (how easily the disease spreads).

Virulence

How severe or deadly a disease is.

Transmission

How easily an infectious disease spreads between people.

Virulence versus transmission

A disease can be highly virulent but spread less easily, or be less virulent but spread readily.

Reproduction number (R₀)

Estimates the number of people one infected person can infect in a population without immunity.

R₀ = 1

The infection persists.

R₀ less than 1

The infection tends to die away.

R₀ greater than 1

The infection spreads.

Very high transmission examples

Measles (R₀ 12–18) and chickenpox (R₀ 10–12).

Moderate transmission examples

Pertussis (R₀ approximately 5) and early COVID-19 (R₀ approximately 2–3).

Lower transmission examples

Seasonal influenza and Ebola (R₀ approximately 1–2 each, as listed in the lecture).

SARS

Severe Acute Respiratory Syndrome; a coronavirus disease associated with the 2003 Canadian outbreak.

SARS transmission and features

Spread through coughs or sneezes; symptoms include fever, cough, difficulty breathing, headaches, diarrhea, and sore throat.

COVID-19 transmission and severity

Highly transmissible; severity ranges from mild to severe depending on the variant and host.

COVID-19 treatments listed in the lecture

Steroids and supportive therapy, including oxygen or ventilation.

COVID-19 vaccine challenges

Rapid viral mutation can require vaccine modifications and frequent boosters.

Causes of death in high-income countries

The lecture highlights high blood pressure, smoking, obesity, and aging.

Major cause of death in low-income countries

Infections, particularly respiratory infections and diarrheal diseases.

Top five worldwide risk factors for disease and death

1. Smoking; 2. Inactivity/obesity; 3. Malnutrition; 4. Alcohol; 5. Air pollution.