Chapter 15
Diseases
By Boundless
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The epidermis includes five main layers: the stratum corneum, stratum lucidium, stratum granulosum, stratum spinosum, and stratum germinativum.
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The skin flora, more properly referred to as the skin microbiome or skin microbiota, are the microorganisms that reside on the skin.
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Bacterial skin infections include impetigo, erysipelas, and cellulitis.
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Virus-related cutaneous conditions include cold sores, shingles, and warts.
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Common fungal skin diseases include athlete's foot, jock itch, and ringworm.
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Parasites can cause skin infections and common examples include creeping eruption, lice, and scabies.
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Many structures in the human eye, such as the cornea and fovea, process light so it can be deciphered by rods and cones in the retina.
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A small number of bacteria are normally present in the conjunctiva.
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Conjunctivitis is inflammation of the conjunctiva, most commonly due to an infection.
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Fungi and viruses such as herpes simplex can cause eye infections.
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The primary function of the nervous system is to coordinate and control the various functions of our body.
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The CNS includes the brain and spinal cord, while the PNS is a network of nerves linking the body to the brain and spinal cord.
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Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges.
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Botulism is a rare but sometimes fatal paralytic illness caused by botulinum toxin produced by the bacterium Clostridium botulinum.
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Leprosy, also known as Hansen's disease, is a chronic bacterial disease caused by Mycobacterium leprae and Mycobacterium lepromatosis.
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Tetanus is a medical condition characterized by a prolonged contraction of skeletal muscle fibers.
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Botulinum toxin is a protein and neurotoxin, which blocks neuromuscular transmission through decreased acetylcholine release.
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Rabies is a viral disease that causes acute encephalitis in warm-blooded animals.
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Poliomyelitis is an infection by the polio virus that affects the motor neurons of the central nervous system.
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Hantaviruses are negative-sense RNA viruses that sometimes lead to hemorrhagic fever with renal syndrome in humans.
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Arboviral encephalitis (acute swelling in the brain) is caused by a group of arthropod-transmitted viruses.
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Rickettsia is a genus of bacteria that can be transmitted by arthropod vectors to humans, causing diseases.
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Lyme disease is caused by bacteria from the Borrelia genus.
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West Nile virus is a mosquito-borne arbovirus found in temperate and tropical regions of the world.
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The plague is an infectious disease caused by the Gram-negative rod-shaped bacteria Yersinia pestis.
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Cryptococcosis is a disease caused by fungi that can be fatal.
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Sleeping sickness is caused by a protozoa transmitted by the tsetse fly.
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Amoebic meningoencephalitis is an often-fatal central nervous system infection caused by Naegleria fowleri.
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Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative disease in cows.
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Variant Creutzfeldt–Jakob Disease (vCJD) is a fatal neurological disorder which is caused by prions.
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Chronic fatigue syndrome (CFS) is the most common persistent fatigue syndrome that affects people.
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The lymphatic system plays a prominent role in immune function, fatty acid absorption, and removal of interstitial fluid from tissues.
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Both the cardiovascular system and the lymphatic system are susceptible to diseases caused by microorganisms.
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The lymphatic system consists of lymphatic vessels and associated lymphoid organs.
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The circulatory system has a defence against microbial invaders in the form of the lymphatic system.
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Septic shock occurs when a body's response to an infection (sepsis) leads to life-threatening low blood pressure.
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Bacterial endocarditis is an infection of the inner surface of the heart or heart valves caused by the presence of bacteria in the blood.
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Rheumatic fever is an inflammatory disease that can develop as a complication of inadequately treated strep throat.
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Tularemia is an infection caused by the Gram-negative bacteria Francisella tularensis.
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Brucellosis is an infectious disease that occurs from contact with animals carrying Brucella bacteria.
Anthrax is a rare, infectious disease caused by Bacillus anthracis that can spread from animals to humans.
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Gangrene is a serious and potentially life-threatening condition that arises when a considerable mass of body tissue dies.
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Burkitt's lymphoma is a very fast growing form of non-Hodgkin's lymphoma, a cancer in the lymphatic system.
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Mononucleosis is an infectious disease caused by the Epstein-Barr virus (EBV) and results in flu-like symptoms.
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Epstein-Barr virus (EBV) is a member of the herpesvirus family and is best known as the cause of infectious mononucleosis.
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Cytomegalovirus (CMV) is a type of herpesvirus that largely affects infants and the immunocompromised.
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Chikungunya (CHIKV) is a mosquito-borne viral disease which causes fever and severe joint pain.
Viral hemorrhagic fevers (VHFs) are a group of illnesses that are caused by several distinct families of RNA viruses.
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As human habitation expands, new viral hemorrhagic fevers are infecting humans.
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Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and transmitted via the reduviid bug.
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Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii and its life cycle mandates a definitive host which are cats.
Malaria is a mosquito-borne infectious disease that affects humans and other animals caused by various species of the protist Plasmodium.
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Leishmaniasis is caused by the protozoan parasite Leishmania and presents itself in two forms: cutaneous or visceral leishmaniasis.
Babesiosis is a malaria-like parasitic disease caused by infection with Babesia, a parasite transmitted to human hosts by ticks.
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Schistosomiasis is a parasitic disease caused by various species of trematodes or "flukes," which are of the genus Schistosoma.
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Swimmer's itch is a result of an immune reaction in response to the penetration of the skin by a schistosome.
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The respiratory system include lungs, airways and respiratory muscles. Ventilation is the rate at which gas enters or leaves the lung.
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Airborne diseases are characterized by diseases that are transmitted through the air via the presence of a pathogen.
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Pharyngitis is an inflammation of the throat that has many causes, some of which are bacterial infections.
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Scarlet fever is caused by a bacteriophage that infects Streptococcus pyogenes.
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Diphtheria is an upper respiratory infection that is largely benign unless left untreated, at which point very harmful toxins are produced.
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Otitis media, or earache, is the inflammation of the middle ear and is often due to bacterial infections.
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Pertussis, more commonly known as whooping cough, is a bacterial infection of the upper respiratory system.
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Tuberculosis is a common, and in many cases lethal, infectious bacterial disease that mainly affects the lungs.
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Pneumonia is an inflammatory lung disease that can lead to problems with breathing, often caused by bacterial infections.
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The common cold is caused by several different viruses and is the most common human viral infection.
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Viral pneumonia, one of the two leading causes of pneumonia, more commonly affects children.
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Human respiratory syncytial virus (RSV) causes respiratory tract infections in humans.
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Influenza is an infectious disease caused by RNA viruses of the family Orthomyxoviridae that affects birds and mammals.
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Histoplasmosis is a disease caused by the fungus Histoplasma capsulatum.
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Coccidioidomycosis is a fungal disease caused by Coccidioides immitis or C. posadasii.
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Pneumocystis pneumonia (PCP) or pneumocystosis is a form of pneumonia, caused by the yeast-like fungus Pneumocystis jirovecii.
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Blastomycosis is a fungal infection caused by the organism Blastomyces dermatitidis.
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Sporotrichosis is a disease caused by the fungus Sporothrix schenckii.
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The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus.
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Gut flora consist of microorganisms that live in the digestive tracts of animals and are the largest reservoir of human flora.
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The mouth contains a wide variety of oral bacteria, but only a few specific species of bacteria are believed to cause tooth and gum infections.
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Dental caries cause demineralization of the hard tissues and destruction of the organic matter of the tooth.
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Plaque-induced inflammatory lesions make up the vast majority of periodontal diseases, which are divided into peridontitis or gingivitis.
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Gastroenteritis is characterized by inflammation of the gastrointestinal tract that involves both the stomach and the small intestine.
Staphylococcal toxins are a common cause of food poisoning, as they can be produced in improperly-stored food.
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Salmonellosis is an infection by the Salmonella bacteria that results in diarrhea, fever, vomiting, and abdominal cramps.
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Typhoid fever is a common, worldwide bacterial disease transmitted by Salmonella typhi, serotype Typhi.
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Cholera is an infection in the small intestine caused by the bacterium Vibrio cholerae.
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Vibrio is a Gram-negative bacteria possessing a curved rod shape (comma shape), several species of which can cause foodborne infection.
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Most E. coli strains are harmless, but some serotypes are pathogenic and can cause serious food poisoning in humans and other species.
Campylobacter (meaning 'twisted bacteria') is a genus of bacteria that are Gram-negative, spiral, and microaerophilic.
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A peptic ulcer, also known as peptic ulcer disease, is an erosion in the wall of the stomach, duodenum, or esophagus.
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Listeriosis is a bacterial infection caused by a Gram-positive, motile bacterium called Listeria monocytogenes.
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Mumps was a common childhood viral disease, but widespread vaccination has now made it rare in developed countries.
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Hepatitis is the inflammation of the liver. Causes include viruses, bacterial infections, alcohol, autoimmune disorders, drugs, and toxins.
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Gastroenteritis is caused by two different virus types in adults and children.
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Ergot poisoning is caused by ingestion of the alkaloids produced by the ergot fungi.
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Aflatoxin poisoning is a result of ingestion of aflatoxins produced by Aspergillus that have contaminated a food source.
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Giardiasis, sometimes referred to as beaver fever, is caused by the protozoan Giardia lamblia and results in diarrheal illness.
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Cryptosporidiosis is a type of parasitic disease caused by Cryptosporidium that infects the gastrointestinal system.
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Cyclospora diarrheal infection is commonly referred to as traveler's diarrhea and is caused by the parasite Cyclospora cayetanensis.
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Amoebic dysentery is caused by the parasite Entamoeba histolytica and infected individuals suffer from severe diarrhea, cramps, and fever.
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Legionellosis is most commonly caused by the Gram-negative bacteria Legionella pneumophila which is an aquatic organism.
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Tapeworms are helminths capable of targeting the digestive system, but require various hosts for successful growth and transmission.
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Hydatid disease, also referred to as cystic echinococcosis, is characterized by the slow growth of large cysts within various organs.
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Nematodes, or roundworms, are capable of exhibiting parasitic behavior.
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The human reproductive system functions to produce human offspring, with the male providing sperm and the female providing the ovum.
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The urinary system maintains blood homeostasis by filtering out excess fluid and other substances from the bloodstream and secreting waste.
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The vaginal microflora consist mostly of various lactobacillus species.
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A urinary tract infection (UTI) is an infection affecting the urinary tract; about 150 million people develop UTIs each year.
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Cystitis is a urinary bladder inflammation that is most commonly caused by a bacterial infection of the lower urinary tract infection.
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Pyelonephritis is an inflammation of the kidney tissue and surrounding area, commonly caused by a bacterial infection ascending up the upper urinary tract.
Leptospirosis is a rare and severe infection caused by Leptospira bacteria and usually transmitted to people from animals.
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Prostatitis is an inflammation of the prostate which can be caused by bacteria.
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Prostatitis is an inflammation of the prostate which can be caused by bacteria.
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Gonorrhea (also colloquially known as the clap) is a common human sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae.
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Nongonococcal urethritis (NGU) is an urethral inflammation that is not caused by Neisseria gonorrhoeae.
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Pelvic inflammatory disease (PID) is an inflammation of the female reproductive organs that is most often caused by infection.
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Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum.
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Genital ulcers are skin ulcers on the genital area caused by sexually transmitted diseases or noninfectious conditions.
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Lymphogranuloma venereum (LGV) is a sexually transmitted disease which causes an infection of the lymph nodes.
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Group B streptococcus is part of the natural microflora in some people, but can sometimes cause life-threatening infections.
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Chancroid is a sexually transmitted disease caused by Haemophilus ducreyi.
Bacterial vaginosis (BV) is a condition of disrupted balance of the vaginal microflora.
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Chlamydia infection is a common sexually transmitted infection (STI) in humans caused by the bacterium Chlamydia trachomatis.
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Herpes genitalis (or genital herpes) refers to a genital infection by Herpes simplex virus.
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Genital warts is a highly contagious sexually transmitted disease caused by some sub-types of human papillomavirus (HPV).
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Human immunodeficiency virus infection/acquired immunodeficiency syndrome is a disease of the human immune system caused by HIV.
Human papillomavirus (HPV) is a virus from the papillomavirus family that is capable of infecting humans.
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Candidal vulvovaginitis is an infection of the vagina's mucous membranes caused by Candida albicans.
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Trichomoniasis is primarily an infection of the urogenital tract; the most common site of infection is the urethra and the vagina in women.
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TORCH infections are a group of viral, bacterial, and protozoan infections that gain access to the fetal bloodstream from the mother.