Chapter 4 Communicable and Noncommunicable Diseases Prevention and

Chapter 4 Communicable and Noncommunicable Diseases: Prevention and Control of Diseases and Health Conditions

Chapter Objectives (1 of 2) After studying this chapter, you will be able to: 1. Explain the differences between communicable (infectious) and noncommunicable (noninfectious) diseases and between acute and chronic diseases and provide examples of each. 2. Describe and explain communicable and multicausation disease models. 3. Explain how communicable diseases are transmitted in a community using the “chain of infection” model and use a specific communicable disease to illustrate your explanation. 4. Explain why noncommunicable diseases are a community and public health concern and provide some examples of important noncommunicable diseases. 5. Explain the difference between primary, secondary, and tertiary prevention of disease and provide examples of each.

Chapter Objectives (2 of 2) 6. List and explain the various criteria that communities might use to prioritize their health problems in preparation for the allocation of prevention and control resources. 7. List and discuss important measures for preventing and controlling the spread of communicable diseases in a community. 8. List and discuss approaches to noncommunicable disease control in the community. 9. Define and explain the purpose and importance of health screenings. 10. Outline a chronic, noncommunicable disease control program that includes primary, secondary, and tertiary disease prevention components.

Introduction • Diseases and other health conditions are classified in several meaningful ways • Classification can lead to prevention and control strategies

Classification of Diseases and Health Problems • In community health, diseases are usually classified as: – Acute or chronic (<3 or >3 months) – Communicable or noncommunicable

Communicable versus Noncommunicable Diseases • Communicable (infectious) diseases – those diseases for which biological agents or their products are the cause and that are transmissible from one individual to another • Noncommunicable (noninfectious) diseases – those illnesses that cannot be transmitted from one person to another – Identifying cause is difficult because many factors can contribute

Acute versus Chronic Diseases and Illnesses • Diseases classified by duration of symptoms • Acute – diseases in which peak severity of symptoms occurs and subsides within 3 months – Can be communicable or noncommunicable • Chronic – diseases or conditions in which symptoms continue longer than 3 months • Can be communicable or noncommunicable

Communicable Diseases • Infectivity: ability of a biological agent to enter and grow in the host – Agent: cause of disease or health problem – Host: susceptible person or organism invaded by an infectious agent – Environment: factors that inhibit or promote disease transmission • Pathogenicity: capability of a communicable agent to cause disease in a susceptible host

Biological Agents of Disease

Communicable Disease Model

Chain of Infection (1 of 3) • Step-by-step model to conceptualize the transmission of a communicable disease from its source to a susceptible host

Chain of Infection (2 of 3) • Pathogen: disease-causing agent (virus, bacterium, etc. ) • Reservoir: favorable environment for infectious agent to live and grow (human, animal, etc. ) • Portal of exit: path by which agent leaves host • Transmission: how pathogens are passed from reservoir to next host • Portal of entry: where agent enters susceptible host • New host: susceptible to new infection being established

Chain of Infection (3 of 3) • Zoonoses – diseases for which the reservoir resides in animal populations • Anthroponoses – diseases for which humans are the only known reservoir

Modes of Transmission • Direct transmission – immediate transfer of disease agent between infected and susceptible individuals – Touching, biting, kissing, sexual intercourse • Indirect transmission – transmission involving an intermediate step – Airborne, vehicleborne, vectorborne, biological – Vehicles – nonliving objects by which agents are transferred to susceptible host

Chain of Infection Example • Agent (cold virus), leaves reservoir (throat of infected person), when host sneezes (portal of exit: nose and mouth). Direct transmission (saliva droplets) enter respiratory tract of susceptible host at close range (portal of entry: mouth). New infection possibly established. If one link is missing, chain is broken.

Noncommunicable Diseases • Nation’s leading causes of death – Heart disease, stroke, cancer • Complex etiologies (causes) • Multicausation disease model – Host: inalterable, unique genetic endowment – Personality, beliefs, behavioral choices: impact host – Complex environment: exposes host to risk factors

Multicausation Disease Model

Noncommunicable Diseases • Diseases of the heart and blood vessels – Coronary heart disease – Cerebrovascular disease (stroke) • • Malignant neoplasms (cancer) Chronic obstructive pulmonary disease Diabetes mellitus Chronic liver disease and cirrhosis

Prioritizing Prevention and Control Efforts • Criteria used to judge importance of disease to a community – Number of people who will die from a disease • Leading causes of death – Number of years of potential life lost • Captures issues affiliated with various groups – Economic costs associated with disease • Money spent at various levels of government; ex: alcohol and other drugs

Prevention, Intervention, Control, and Eradication of Diseases • Prevention: planning for and taking action to prevent or forestall onset of disease or health problem • Intervention: effort to control disease in progress; taking action during an event • Control - containment of a disease; prevention and intervention measures • Eradication: total elimination of disease from human population

Levels of Prevention • Primary prevention – Forestall onset of illness or injury during prepathogenesis period • Secondary prevention – Early diagnosis and prompt treatment before disease becomes advanced and disability severe • Tertiary prevention – Aimed at rehabilitation following significant pathogenesis; retrain, reeducate, rehabilitate

Primary Prevention of Communicable Diseases • Strategies at each link in chain of infection – Individuals • Hand washing, using condoms, properly cooking food – Communities • Chlorinating water supply, inspecting restaurants, immunization programs for all citizens, vector control, solid waste disposal

Immunity • Important component of primary prevention – Active immunity - occurs when exposure to a disease-causing organism prompts the immune system to develop antibodies against that disease – Passive immunity - occurs when a person receives antibodies against a disease rather than their immune system producing them

Secondary Prevention of Communicable Diseases • Individuals – Self-diagnosis, self-treatment with home remedies – Antibiotics prescribed by a physician • Communities – Controlling or limiting extent of an epidemic • Carefully maintaining records; investigating cases • Isolation, quarantine, disinfection

Tertiary Prevention of Communicable Diseases • Individuals – Recovery to full health after infection; return to normal activity • Communities – Preventing recurrence of epidemics • Removal, embalming, burial of dead • Reapplication of primary and secondary measures

Primary Prevention of Noncommunicable Diseases • Individuals – Education and knowledge about health and disease prevention, eating properly, adequate exercise, driving safely • Communities – Adequate food and energy supplies, efficient community services, opportunities for education, employment, and housing

Secondary Prevention of Noncommunicable Diseases • Individuals – Personal screenings (mammogram, pap test, PSA test), regular medical and dental checkups, pursuit of diagnosis and prompt treatment • Communities – Provision of mass screenings for chronic diseases, case-finding measures, provision of adequate health personnel, equipment, and facilities

Tertiary Prevention of Noncommunicable Diseases • Individuals – Significant behavioral or lifestyle changes, adherence to prescribed medications, following rehabilitation requirements after surgery • Communities – Adequate emergency medical personnel and services: hospitals, surgeons, nurses, ambulance services

Discussion Questions • Which components of the Multicausation Disease Model can communities most effectively impact? • Which level of prevention is most important for better community health outcomes and why? • Who plays a more significant role in preventing diseases, individuals or communities?