Infectious & Non-Infectious Diseases

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Infectious Non-Infectious Diseases
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Infectious Diseases

• Infectious diseases are caused by pathogenic
  microorganisms, such as bacteria, viruses,
  parasites or fungi the diseases can be spread,
  directly or indirectly, from one person to
  another.

How Infections Occur
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Methods of Transmission

• Droplet Contact
• Also known as the respiratory route, it is a
  typical mode of transmission among many
  infectious agents. If an infected person coughs
  or sneezes on another person the microorganisms,
  suspended in warm, moist droplets, may enter the
  body through the nose, mouth or eye surfaces.
  Diseases that are commonly spread by coughing or
  sneezing include (at least)

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Droplet Transmission (cont.)

• Bacterial Meningitis
• Chickenpox
• Common cold
• Influenza
• Mumps
• Strep throat
• Tuberculosis
• Measles
• Rubella
• Whooping cough

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Fecal Oral Transmission

• Direct contact is rare in this route, for humans
  at least. More common are the indirect routes
  foodstuffs or water become contaminated (by
  people not washing their hands before preparing
  food, or untreated sewage being released into a
  drinking water supply) and the people who eat and
  drink them become infected. In developing
  countries most sewage is discharged into the
  environment or on cropland as of 2006 even in
  developed countries there are periodic system
  failures resulting in a sanitary sewer overflow.
  This is the typical mode of transmission for the
  infectious agents of (at least)
• Cholera
• Hepatitis A
• Polio
• Rotavirus
• Salmonella

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Sexual Transmission

• This refers to any disease that can be caught
  during sexual activity with another person,
  including vaginal or anal sex or (less commonly)
  through oral sex. Transmission is either directly
  between surfaces in contact during intercourse
  (the usual route for bacterial infections and
  those infections causing sores) or from
  secretions (semen or the fluid secreted by the
  excited female) which carry infectious agents
  that get into the partner's blood stream through
  tiny tears in the penis, vagina or rectum (this
  is a more usual route for viruses).
• Some diseases transmissible by the sexual route
  include (at least)
• HIV/AIDS
• Chlamydia
• Genital warts
• Gonorrhea
• Hepatitis B
• Syphilis
• Herpes

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Transmission by Direct Contact

• Diseases that can be transmitted by direct
  contact are called contagious . These diseases
  can also be transmitted by sharing a towel (where
  the towel is rubbed vigorously on both bodies) or
  items of clothing in close contact with the body
  (socks, for example) if they are not washed
  thoroughly between uses. For this reason,
  contagious diseases often break out in schools,
  where towels are shared and personal items of
  clothing accidentally swapped in the changing
  rooms.
• Some diseases that are transmissible by direct
  contact include
• Athlete's foot
• Impetigo
• Syphilis (on rare occasions, if an uninfected
  person touches a chancre)
• Warts

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Vector Borne Transmission

• A vector is an organism that does not cause
  disease itself but that transmits infection by
  conveying pathogens from one host to another.
• Examples include mosquitoes, deer ticks, animal
  bites, etc.

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Test Your Knowledge!

• Is It Contagious?

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Non Infectious Disease

• Non-infectious diseases (also called
  Non-communicable diseases ) are those diseases
  that are not caused by a pathogen and cannot be
  shared from one person to another.
• Non-infectious diseases may be caused by either
  the environment, nutritional deficiencies,
  lifestyle choices, or genetic inheritances.
  Unlike infectious diseases, non-infectious
  diseases are not communicable or contagious,
  although some kinds can be passed down
  genetically to the children of a carrier.

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Infectious vs. Non-Infectious

• Historically, infectious diseases were the main
  cause of death in the world and, indeed, in some
  developing regions this may still be the case.
  With the development of antibiotics and
  vaccination programs, infectious disease is no
  longer the leading cause of death in the western
  world. Non-infectious disease is now responsible
  for the leading causes of death in both developed
  and some developing countries.

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Causes of Non-Infectious Disease

• Causes of non-infectious disease are categorized
  into genetically inherited diseases and
  environmental diseases. Non-infectious diseases
  that are not genetic disorders are environmental
  diseases, although many diseases are affected by
  both genetic and environmental factors.

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Inherited Diseases

• Genetic disorders are caused by errors in genetic
  information that produce diseases in the affected
  people. These errors may include
• A change in the chromosome numbers, such as Down
  syndrome
• A defect in a single gene caused by mutation,
  such as Cystic Fibrosis.

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Environmental Diseases

• Environmental disease is a very broad category.
  It includes avoidable and unavoidable conditions
  caused by external factors, such as sunlight,
  food, pollution, and lifestyle choices. The
  diseases of affluence are non-infectious diseases
  with environmental causes. Examples include
• Many types of cardiovascular disease
• Chronic obstructive pulmonary disease caused by
  smoking tobacco
• Type 2 Diabetes
• Malnutrition caused by too little food, or eating
  the wrong kinds of food (e.g. scurvy from lack of
  Vitamin C)
• Skin cancer caused by radiation from the sun

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Cancer

• Cancer is a non-infectious disease that affects
  millions of people. The National Cancer Institute
  reports the most common cancer type as
  nonmelanoma skin cancer, with about one million
  cases a year. Lung cancer is the second-most
  common, with about 219,440 new cases and 159,390
  deaths. Other common cancers include bladder,
  breast, leukemia, pancreatic, prostate, thyroid,
  colorectal, endometrial and kidney cancer.

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Heart Disease

• Mayo Clinic reports heart disease, a
  non-infectious disease, as the number-one killer
  in the United States. Heart or cardiovascular
  disease refers to a variety of conditions that
  involve the circulatory system. Heart attacks,
  strokes, chest pain, tachycardia, high
  cholesterol, heart valve disease, high blood
  pressure, palpitations and congenital heart
  disease are some of the non-infectious heart
  diseases.

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Kidney Disease

• The National Kidney Foundation reports chronic
  kidney disease (CKD) is a non-infectious disease
  that affects about 26 million Americans. CKD
  results when the kidneys are no longer able to
  remove wastes from the body. Diseases such as
  diabetes, high blood pressure, lupus, kidney
  stones and polycystic kidney disease may hinder
  the kidneys' ability to process and remove
  wastes.

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Mental Disease

• Mental disease covers a broad range of
  non-infectious diseases that affects people of
  all ages. Autism, panic attacks, narcolepsy,
  manic-depressive disorder, depression, bulimia
  nervosa, bipolar disorder and Asperger's syndrome
  are examples of non-infectious mental diseases.

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Bone Disease

• Non-infectious bone diseases include
  osteoporosis, Paget's disease and osteogenesis
  imperfecta. Osteoporosis indicates a low bone
  mass, fragile bones, and high risk of bone
  fractures. Paget's disease presents as bones that
  grow larger and weaker than normal bones.
  Osteogenesis imperfecta (OI) is a non-infectious
  genetic disorder. OI symptoms include bones that
  break easily.

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Muscle Joint Disease

• Non-infectious muscle and joint diseases include
  fibromyalgia, rheumatoid arthritis and gout.
  Fibromyalgia is a chronic non-infectious disease
  identified as pain and tender points in soft
  tissue, muscles and joints throughout the body.
  Merck Manual, an online medical library, reports
  rheumatoid arthritis (RA) affects about one
  percent of the world's population. RA symptoms
  range from mild occasional joint pain to severe
  and debilitating pain. Gout is a non-infectious
  disease caused by high levels of uric acid in the
  joints and manifests as sudden severe joint pain,
  possibly accompanied by fever and feeling ill.

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Diabetes

• When carbohydrates are eaten, they get converted
  to glucose which is blood sugar. To stabilize
  blood sugar levels, the pancreas releases
  insulin. In people that have diabetes, a
  noninfectious disease, the pancreas does not
  release insulin properly or at all in the most
  severe cases. This can cause kidney failure,
  blindness, nerve damage and heart problems.