Infection, Immunity, and Noninfectious Disease

Diseases Processes that affect proper body functioning accompanied by associated signs and symptoms Noninfectious diseases - caused by genetic abnormalities, environmental factors, or a combination of both Cystic fibrosis, lead-poisoning, asthma Infectious diseases - caused by pathogens such as bacteria, viruses, fungi, parasitic worms Colds, flu, sexually transmitted infections

Genetic Diseases Two types: Inherited diseases (inherit “defective” gene) and diseases caused by errors when gametes are formed Defective (mutated) genes caused by ionizing radiation, toxic chemicals, drugs Common inherited diseases in the U.S. Sickle-cell anemia Cystic fibrosis Duchenne muscular dystrophy

Noninfectious Diseases Caused by an Interaction of Genes and Environment Asthma Narrowed airway passages and difficulty breathing Attacks can be triggered by air pollution, URIs, smoke, dust Ulcers Diabetes mellitus Migraine headaches Cardiovascular disease Cancer

Trends in Infectious Disease Infectious diseases are not significant contributors to death in the U.S. today Worldwide, infectious diseases are the leading cause of death Many strains of bacteria have become resistant to antibiotics With international travel commonplace, transmission of infection is a worldwide concern

Chain of Infection Agent of Infection (Pathogen) Transmission Host

Pathogens Bacteria (unicellular organisms with a simple cell structure) Cause diseases such as strep throat, pneumonia, food infection Rickettsias (bacterialike organisms that live within host cells) Cause diseases such as typhus, Rocky Mountain Spotted Fever

Pathogens (cont’d) Viruses (hereditary material with a protein coat) Cause diseases such as cold, flu, mumps, measles, chicken pox, hepatitis, HIV infection Fungi (cause opportunistic infections) Cause diseases such as athlete’s foot, yeast infections

Ringworm

Toenail fungus

Pathogens (cont’d) Protozoans (single-celled organisms with a complex cell structure) Cause disease such as malaria, “trich” infections Parasitic worms Tapeworms, roundworms, flukes Live in digestive system and cause digestive disorders. Flukes can also inhabit the liver, lungs, or veins.

Pathogens (cont’d) Arthropods Lice, fleas, mites, and ticks Cause infestations of various body parts

Transmission of Disease Noncommunicable Communicable

Noncommunicable Diseases Caused by: Growth of bacteria that normally inhabit the body Skin infections Ingestion of toxins or poisons produced by some bacteria Food poisoning or food infection Pathogens that infect people via environment or animal sources

Communicable Diseases Transmitted from person to person by direct or indirect contact a common vehicle (food, water, a common drinking glass) the air vectors (organisms other than humans, such as mosquitoes)

Host Stress can reduce resistance to infection Exhaustive exercise can lower immune system function Race and age affect resistance or susceptibility to disease

Treating Infections Antibiotics (kill or inhibit growth of bacteria) Over-the-counter medications can sometimes relieve symptoms Specific medications have been developed to treat certain viral and protozoan infections, and worm infestations

Sexually Transmitted Infections Spread from person-to-person by intimate contact Caused by certain viruses, bacteria, yeasts, and protozoans Infestations caused by certain mites and lice

HIV Transmission Sexual contact with infected person Semen, vaginal secretions, or blood Tears in skin and mucous membranes Exposure to infected blood or blood products Shared needles Blood transfusions Placental transfer during fetal development, labor/delivery, and breastfeeding

Yeast Infections Candidiasis Acquired through intercourse or develops in women after taking antibiotics Itching, burning, irritation, swelling, and white vaginal discharge Can be treated with OTC antifungal creams Males may experience irritation, swelling, and a rash or white patches

SUMMARY Noninfectious diseases have hereditary or environmental causes, or a combination of both Genetic diseases are inherited Two primary causes of infectious diseases are bacteria and viruses The human body combats infectious disease with both specific and nonspecific types of immunity

SUMMARY (cont’d) The severity of a disease depends on: the type of organism its virulence how it spreads in the body the chemicals it produces its ability to combat the defense mechanisms of the body the body’s reaction to the pathogen

SUMMARY (cont’d) Many drugs have been developed to combat infection Adolescents and young adults are at highest risk for contracting STIs