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Definition
Measles virus produces necrosis of the infected respiratory epithelium and vasculitis of the small blood vessels of the skin
•Characterized by upper respiratory tract symptoms, fever, cough and a rash
After incubation period, erythematous, maculopapularrash appears on facial skin that spreads to the trunk and extremities |
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Infection during early gestation can produce fetal death, premature delivery, and congenital anomalies, including deafness, cataracts, glaucoma, heart defects, and mental retardation
•Heart, eye, and brain are most frequently affected (pulmonary valvular stenosis, pulmonary artery hypoplasia, ventricular septal defects, and patent ductusarteriosus)
•Ocular abnormalities are characterized by cataracts, glaucoma, and retinal defects
•Deafness is a common complication of fetal rubella |
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Definition
Begins with viral infection of the respiratory tract epithelium then disseminates through the blood and lymphatic systems to the salivary glands (especially the parotid),CNS, pancreas, and testes.
•50% of cases involve the CNS
•Epididymo-orchitis occurs in 30% of males infected after puberty
•Virus produces necrosis of the infected cells with lymphocytic inflammatory infiltrate
•Affected salivary glands are swollen and the ducts are lined by necrotic epithelium |
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Spreads by the respiratory route, or by contact with secretions from the skin lesions
•Causes chickenpox and herpes zoster
•Primary exposure produces chickenpox, while latent virus, and its reactivation causes herpes zoster ("shingles")
•Virus establishes latent infection in perineuronal satellite cells of the dorsal root ganglia
•Shingles occurs when the replication of the virus is reactivated in the dorsal root ganglion cells and the agent travels along the sensory root, producing painful vesicular eruption
Skin lesions of chickenpox and shingles are indistinguishable from each other or from the lesions produced by herpes simplex virus
•Skin lesions begin as maculopapulesthat rapidly evolve into vesicles The lesions heal in several weeks
•Vesicle fills with neutrophils and erodes to become a shallow ulcer
•Incubation period extends from 11 to 21 days
•Chickenpox presents with fever, malaise, and a distinctive pruriticrash, initially on the head and then the trunk and extremities |
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| Herpes Simplex Virus (HSVs) |
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Definition
Two antigenically and epidemiologically distinct HSVs, namely HSV-1 and HSV-2, cause disease in humans
•HSV-1 is transmitted in oral secretions and causes disease "above the waist" including oral, facial, and ocular lesions
•HSV-2 is transmitted in genital secretions and produces disease "below the waist," including genital ulcers and neonatal herpes infection
•Infected areas undergo necrosis
•Spreads primarily through direct contact with infected secretions or open lesions |
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| Herpes Simplex Virus (HSVs) |
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Definition
Produces recurrent, painful vesicular eruptions of the skin and mucous membranes
•Initial sites of viral inoculation include the oropharynx, genital mucosa, or skin
•Brain, eye, liver, lungs, may also be affected
•Virus invades sensory nerve endings in the oral or genital mucosa, ascends within axons, and establishes a latent infection in sensory neurons within the corresponding ganglia
•When latent infection is reactivated, the virus travels down the nerve to the epithelial site served by the ganglion, where it again infects the epithelial cells |
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Definition
Oro-labial herpes
Conjunctivitis, keratitis
Encephalitis Herpetic Esophagitisa Pneumonia Disseminated infection' |
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Genital herpes
Perinatal infection
Disseminated infection° |
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Produces infectious mononucleosis results from infection with Epstein-Barr virus (EBV)
•Characterized by fever, pharyngitis, lymphadenopathy, and increased circulating lymphocytes
•Infection with EBV has also been associated with several cancers, including: African Burkittlymphoma, B-cell lymphomas in immunosuppressedpersons, and nasopharyngeal carcinoma
•EBV spreads primarily through contact with infected oral secretions. Once infected, persons remain asymptomatically infected for life, and a few (10-20%) intermittently shed EBV
EBV Virus first binds to and infects nasopharyngeal cells and then B lymphocytes
•Circulating B lymphocytes carry the virus throughout the body, producing a generalized infection of the lymphoid tissues
•Activated B cells stimulate the proliferation of specific killer T lymphocytes and suppressor T cells
•Killer T lymphocytes destroy virally infected B cells, whereas the suppressor cells inhibit production of immunoglobulins by the B cells
•Pathologic changes are prominent in the lymph nodes and spleen
•Splenomegaly occurs as a result of hyperplasia of the red pulp, and becomes susceptible to rupture
•Liver is almost always involved, and the hepatic sinusoids and portal tracts contain atypical lymphocytes |
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Definition
Presents as fever, malaise, lymphadenopathy, pharyngitis, and splenomegaly
•Lymphadenopathy is symmetric and most striking in the neck
•Patients usually have an elevated leukocyte count, with a predominance of lymphocytes and monocytes
•Treatment is supportive, and symptoms usually resolve in 3 to 4 weeks |
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Definition
Human papillomaviruses (HPVs) are DNA viruses, which are members of the papovavirusgroup
•Cause proliferative lesions of the squamous epithelium
•Produce common warts, flat and plantar warts, anogenitalwarts (condyloma acuminatum), and laryngeal papillomatosis
•Infection with HPVs also contributes to the development of squamous cell dysplasiasand squamous cell carcinomas of the genital tract
HPV infection begins with viral inoculation into a stratified squamous epithelium, where they stimulate replication of the squamous epithelium and production of various HPV-associated proliferative lesions
•Common warts (verrucavulgaris) are common in children and assume firm, circumscribed lesions that usually appear on surfaces subject to trauma, especially the hands
•Plantar warts are similar squamous proliferative lesions on the soles of the feet but are compressed inward by standing and walking
•Anogenitalwarts (condyloma acuminatum) are soft, raised, fleshy lesions found on the penis, vulva, vaginal wall, cervix, or perianalregion
•Flat warts in the genital area are now recognized to be more common than typical raised anogenitalwarts
•Flat warts can develop into malignant squamous cell proliferations |
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Definition
S. aureus produces 50% of septic arthritis cases in patients older than 50 years
•Rheumatoid arthritis and corticosteroid therapy are common predisposing conditions |
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Definition
| Septicemia with S. aureus afflicts hospitalized patients with compromised immune system |
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| Staphylococcus aureus - Toxic Shock Syndrome |
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Definition
Most commonly afflicts menstruating women
•Patients present with high fever, nausea, vomiting, diarrhea, myalgias, and eventually, shock
•Associated with use of hyperabsorbenttampons, which provide a site for S. aureus replication and toxin elaboration. |
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| Strep throat" presents as a sore throat with fever, malaise, headache, and an elevated leukocyte count |
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Definition
a localized, intra-epidermal infection of the skin caused by S. pyogenesor S. aureus
•Most commonly affects children from 2 to 5 years of age
•Lesions begin on exposed body surfaces as localized erythematouspapules, which then become pustules that erode within a few days to form a thick, honey-colored crust |
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Definition
•A classic cutaneous streptococcal infection that produces an erythematous swelling of the skin
•caused chiefly by S. pyogenes
•Usually beginning on the face and then spreading rapidly |
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Definition
•Postpartum infection of the uterine cavity by S. pyogenes
•Originates from the contaminated hands of attendants at delivery (observations of Semmelweis) |
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| Streptococcus pneumoniae(pneumococcus) |
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Definition
•Primarily involves the lungs (pneumonia), middle ear (otitismedia), sinuses (sinusitis), and meninges(meningitis)
•One of the most common bacterial pathogens of humans, and by age of 5 years, most children in the world have suffered at least one episode of pneumococcal disease (usually otitismedia) |
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Definition
•Pneumococcus is the second leading cause of bacterial meningitis after infection with Haemophilus influenzae
•Begins usually in the oropharynx
•Pneumococcal sinusitis, otitis media, and pneumonia are usually preceded by a viral illness, such as the common cold
•Exposure to viral respiratory illnesses, smoking, and alcoholism, allows S. pneumoniae to access to the lower respiratory tract and produce lobar pneumonia |
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Definition
•Caused by a Gram-negative coccobacillus
•Causes pyogenicinfections, primarily in young children, involving the middle ear, sinuses, facial skin, epiglottis, meninges, lungs, and joints |
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Definition
•An emergency condition that could cause death if left untreated
•Consists of swelling and acute inflammation of the epiglottis, aryepiglotticfolds, and pyriformsinuses, which sometimes completely obstruct the upper airway |
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| Pertussis (whooping cough) |
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Definition
•a prolonged upper respiratory tract infection characterized by debilitating coughing paroxysmsfollowed by a long, high-pitched inspiration—the "whoop“
•Lasts from 4 to 5 weeks
•Caused by Bordetella pertussis, a small, Gram-negative coccobacillus similar in appearance to Haemophilus sp
•Produces an extensive tracheobronchitis
•Primarily a disease of children younger than 5 years, and many cases occur in children younger than 1 year
•Vaccination protects against B. pertussis |
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Definition
•Caused by Neisseriagonorrhoeae(gonococcus), a Gram-negative diplococcusthat is morphologically indistinguishable from N. meningitidis
•One of the oldest and the most common sexually transmitted diseases
•Produces acute suppurativeinfection of the genital tract and abscesses including urethritisamong men and endocervicitisamong women
•Infection among women often ascends the genital tract, producing endometritis, salpingitis, and pelvic inflammatory disease
•Neonatal infections derived from the birth canal of infected mother with gonorrhea usually present with conjunctivitis (conjunctivitis)remains a major cause of blindness in much of Africa and Asia
•If untreated, the inflammatory response becomes chronic
•Incubation period is 3 to 5 days
•After incubation, men exposed to N. gonorrhoeaepresent with a purulent urethral discharge and dysuriawhich can be arrested by prompt antibiotic treatment, and the organism remains confined to the mucosa of the anterior urethra
•Urethral stricture is a common complication if left untreated
•Approximately 50% of infected women manifest endocervicitis, with vaginal discharge or bleeding
•Infection in women often extends to the fallopian tubes, and produces acute and chronic salpingitisand adhesion, and eventually, pelvic inflammatory disease (PID)
•Gonorrhea is readily eradicated with effective antibiotic regimens, especially penicillin, although resistant strains are encountered |
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Definition
Considered as the most frequent and important bacterial pathogens of humans
•Gram-negative bacteria that are mostly intestinal commensalsand are well adapted to growth within the human colon without causing harm to the host
•E. coli can be aggressive when it gains access to usually sterile body sites, such as the urinary tract |
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Definition
•Gram-positive, spore-forming bacilli that are obligate anaerobes
•Form (bacilli) in the vegetative form that inhabit the gastrointestinal tract of humans and animals
•Spores pass in the feces, contaminate soil and plant material, and are ingested or enter sites of penetrating wounds
•Revert to vegetative forms under anaerobic conditions, releasing toxins that cause several clostridialdiseases |
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Term
| ClostridialFood poisoning |
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Definition
•One of the most common causes of bacterial food poisoning
•An acute, generally benign diarrheal disease usually lasting less than 24 hours
•Spores of C. perfringenssurvive cooking temperatures and germinate to yield vegetative forms that proliferate in unrefrigerated food
•Clostridialfood poisoning results from ingestion of food containing large numbers (>1051g) of these vegetative bacteria |
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Definition
•A severe, acute neurologic syndrome caused by tetanus toxin
•Occurs when C. tetani releases exotoxin in contaminates wounds, blocking release of inhibitory neurotransmitters, and permitting unopposed neural stimulation and contracture of skeletal muscles (tetany)
•Clostridium tetani is present in the soil and the lower intestine
•Characterized by spastic contractions of the skeletal muscles
•Although clostridial infection remains localized, the potent tetanus neurotoxin follows retrograde transport through the ventral roots to the spinal anterior horn cells
•A vaccine composed of inactivated tetanus toxin is highly effective in preventing tetanus
•Incubation period of tetanus is from 1 to 3 weeks
•Spastic rigidity often begins in the muscles of the face, giving rise to "lockjaw" or spastic rigidity of several facial muscles and causing a fixed grin (risussardonicus)
•Rigidity of the muscles of the back produces a backward arching (opisthotonos)
•Abrupt stimuli, including noise, light, or touch, can precipitate painful, generalized muscle spasms
•Swallowing and breathing may be impaired by involvement of the associated muscles
•Prolonged spasm of the respiratory and laryngeal musculature may lead to death
•Administration of antibody to bind unabsorbed toxin, antibiotics to eliminate infection, and supportive care, including respiratory support, remain the mainstays of therapy |
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Definition
•A paralyzing illness that follows ingestion of food containing the preformed neurotoxins of Clostridium botulinum
•Caused by the vegetative form C. botulinumin improperly canned food, or food stored without refrigeration (anaerobic condition for growth of the clostridia)
•Released neurotoxin is absorbed from the small intestine and, eventually, reaches the neuromuscular junction to inhibit the release of acetylcholine
•Patients present with a symmetric, descending paralysis of the cranial nerves, trunk, and limbs, with respiratory paralysis and eventual death |
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Definition
•A necrotizing disease that disseminates from localized sites of infection
•Caused by a large, spore-forming, Gram-positive Bacillus anthracis
•Spores form in the soil and dead animals and can resist heat, desiccation, and chemical disinfection for years
•Infection occurs when spores enter the body through breaks in the skin, by inhalation or by ingestion.
•In 80% of cases of cutaneous anthrax, the infection remains localized, and the host immunologic response eventually overcome the disease
•When organisms are inhaled or ingested, the resulting widespread tissue destruction is usually fatal
•Bacillus anthracis produces extensive tissue necrosis at the sites of infection
•Cutaneous lesions are ulcerated, and are covered by a black scab
•Pulmonary infection produces a necrotizing, hemorrhagic pneumonia associated with hemorrhagic necrosis of the mediastinal lymph nodes |
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Definition
•A systemic infection caused by Listeria monocytogenes, a small, Gram-positive coccobacillus
•Organism grows at refrigerator temperatures, and outbreaks have been traced to contaminated cheese and other dairy products
•Listeriosis of pregnancy includes prenatal and postnatal infections
•Listeriosis of adults is characterized by meningoencephalitis and septicemia
•Maternal infection early in pregnancy leads to abortion or premature delivery
•Infected live born, premature infants develop respiratory distress, hepatosplenomegaly, cutaneous and mucosal papules, leukopenia, and thrombocytopenia
•Widespread abscesses are found in many organs
•Neurologic sequelae are common, and even with prompt antibiotic therapy, the mortality rate is high
•chronic alcoholics, patients with cancer, and those receiving immunosuppressive therapy are all susceptible to listeriosis
•Meningitis is the most common form of the disease in adults and resembles other bacterial meningitides
•Prolonged treatment with antimicrobials is usually required, because patients tend to experience relapse if therapy is administered for less than 3 weeks |
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Definition
•A self-limited infection by Bartonella henselae, a small, Gram-negative rod
•Infection begins when the bacillus is inoculated into the skin by the claws of cats or by thorns or splinters
•Bacteria multiply in the walls of small vessels and collagen fibers
•Infects regional lymph nodes produces suppurative and granulomatous lymphadenitis that drain through the skin
•50% of patients exhibit fever and malaise, rash, brief encephalitis, and erythema nodosum
•Patients develop a papule at the site of inoculation from 3 to 14 days after the scratch, and this papule may persist for 2 months
•No antibiotic has been accepted as beneficial |
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Definition
•Actinomycosis is a slowly progressive, suppurative, fibrosing infection involving mainly the jaw, thorax, or abdomen
•Caused by a number of anaerobic and microaerophilic bacteria, which are termed Actinomyce, which are branching, filamentous, Gram-positive rods that normally reside in the human oropharynx, gastrointestinal tract, and vagina
•Several Actinomyces sp. cause human disease, with the most common being A. israelii
•Actinomyces are not ordinarily virulent, and the organisms reside as saprophytes in the body without producing disease
•Two uncommon conditions must occur for Actinomyces to establish disease:
-First, the organism must be inoculated into the deeper tissues
-Second, an anaerobic atmosphere is necessary for the bacteria to proliferate
-Trauma can produce tissue necrosis, thereby providing an excellent anaerobic medium for the growth of Actinomyces, and can inoculate the organism into normally sterile tissue |
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| Cervicofacial actinomycosis |
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Definition
| results from jaw injury, dental extraction, or dental manipulation. |
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Definition
| is caused by aspiration of organisms contaminating dental debris |
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Definition
| follows traumatic or surgical disruption of the bowel, especially the appendix |
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Definition
is associated with prolonged use of intrauterine devices
•Actinomycosis causes abscesses connected by sinus tracts, which burrow across normal tissue boundaries and into adjacent organs |
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Definition
| •Long, slender, helical bacteria with specialized cell envelopes that permit them to move by flexion and rotation |
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Definition
•A chronic, sexually transmitted, systemic infection caused by Treponema pallidum
•Congenital syphilis may occur as a result of The spread of infection from an infected mother to her fetus
•Course of syphilis is classically divided into three stages: Primary, secondary and tertiary |
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Definition
•Exhibits a chancre , a characteristic ulcer located at the site of T. pallidum inoculation, usually the penis, vulva, anus, or mouth
•Chancre is seen between 1 week to 3 months after exposure
•Microscopically, chancres and lesions of the other stages of syphilis display a characteristic "luetic vasculitis," in which the walls of the vessels become thickened by lymphocytes and fibrous tissue
•Chancre lasts from 3 to 12 weeks and is frequently accompanied by inguinal lymphadenopathy
•Penicillin remains effective therapy at this stage |
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Definition
•Occurs as a result of systemic dissemination and proliferation of T. pallidum
•Produces lesions in the skin, mucous membranes, lymph nodes, meninges, stomach, and liver
•Histopathologically, the lesions are in the form of a chronic, inflammatory infiltrate and endarteritis obliterans
•Most common presentation are erythematous and maculopapular rashes, involving the trunk and extremities and the palms and soles that accompany constitutional symptoms (2 weeks to 6 months)after the chancre heals
•Skin lesions may be in the form condylomata lata (exudative plaques in the perineum, vulva, or scrotum)
•"mucous patches" on the mouth and genital organs are highly infectious
•If untreated, secondary syphilis can relapse |
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Definition
•Asymptomatic period lasts for years or decades after secondary syphilis subsides
•One-third of untreated patients with syphilis develop tertiary lesions
•Tertiary syphilis lesions produce ischemic necrosis secondary to obliterative endarteritis of the small arteries and arterioles
•Affected small arteries are inflamed, and their endothelial cells are swollen surrounded by concentric layers of proliferating fibroblasts, conferring "onion skin" appearance to the vascular lesions |
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Definition
•Results from a slowly progressive endarteritis obliterans of the vasa vasorum that eventually leads to necrosis of the aortic media, gradual weakening and stretching of the aortic wall, and formation of an aortic aneurysm and possible rupture, leading to massive hemorrhage, and sudden death
•Damage to and scarring of the ascending aorta also commonly lead to dilatation of the aortic ring, separation of the valve cusps, and regurgitation of blood through the aortic valve (aortic insufficiency) |
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Definition
•A slowly progressive infection that damages the meninges, cerebral cortex, spinal cord, cranial nerves, or eyes. We will discuss additional info with the nervous system disorders
-Agumma, is a characteristic granulomatous lesion of neurosyphilis, which is composed of a central area of coagulative necrosis, epithelioid macrophages, occasional giant cells, and peripheral fibrous tissue
-Gumma may form in any organ or tissue and is most commonly found in the skin, bone, and joints but, as mentioned, can occur at any body site |
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Definition
•Caused by Borrelia burgdorferi
-a large spirochete which is transmitted from its animal reservoir to humans through the bite of the minute Ixodes tick
-reproduces locally at the site of inoculation, spreads to the regional lymph nodes, and disseminates throughout the body in the bloodstream
-incites a nonspecific, chronic inflammatory infiltrate composed of lymphocytes and plasma cell
•Insect is found in wooded areas, where it usually feeds on mice and deer
•Disease is concentrated in: (1) along the eastern seaboard, from Maryland to Massachusetts; (2) Midwest, in Minnesota and Wisconsin; and (3)West, in California and Oregon
•A chronic, systemic infection that begins with a characteristic skin lesion and later manifests as cardiac, neurologic, or joint disturbances
•Lyme disease occurs in three distinctive stages |
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Definition
•Exhibits distinctive skin lesion, erythema chronicum migrans, which appears at the site of the tick bite
•Erythema chronicum migrans is accompanied by fever, fatigue, headache, arthralgias, and regional lymphadenopathy
•Skin lesion begins as an erythematous macule or papule, and then grows into erythematous patch 5 to 50 cm in diameter
•Treatment with tetracycline or erythromycin is effective in eliminating early Lyme disease |
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Definition
| •Begins within several weeks to months of the skin lesion and is characterized by migratory musculoskeletal pains as well as cardiac and neurologic abnormalities |
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Definition
•Begins months to years after the tick bite and is manifested by joint, skin, and neurologic abnormalities
•Joint abnormalities develop in more than half of infected persons and include severe arthritis of the large joints, especially the knee |
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Definition
•Causes a genital epithelial infection that is now among the most common sexually transmitted diseases in developed countries
•In men, the infection produces urethritis and, sometimes, epididymitis or proctitis
•In women, the infection usually begins with cervicitis, which can progress to endometritis, salpingitis, and generalized infection of the pelvic adnexal organs (pelvic inflammatory disease)
•Repeated infections of the fallopian tubes are particularly associated with
•scarring, which may interfere with the passage of sperm or fertilized ova and result in infertility or ectopic pregnancy
•Chlamydial infection incites an inflammatory infiltrate of neutrophils and lymphocytes
•In newborns, the conjunctival epithelium often contains characteristic vacuolar cytoplasmic inclusions, and the disease is frequently called inclusion conjunctivitis |
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Definition
•A sexually transmitted chlamydial disease that begins as a genital ulcer, progresses to a local necrotizing lymphadenitis, and may eventuate in local scarring
•In North America and Europe, lymphogranuloma venereum is now primarily a disease of homosexual men
•Organism is introduced through a break in the skin
•After an incubation period of 4 to 21 days, an ulcer appears, usually on the penis, vagina, or cervix, although the lips, tongue, and fingers may also be primary sites
•Organism is transported by the lymphatics to the regional lymph nodes, where a necrotizing lymphadenitis, containing multiple, coalescing abscesses that erupt from 1 to 3 weeks after the primary lesion
•Most infections resolve completely, even without antimicrobial therapy
•However, progressive ulceration of the penis, urethra, or scrotum, with fistulas and urethral stricture, develops in 5% of men
•Women and homosexual men often present with hemorrhagic proctitis, and the large majority of late complications, such as rectal stricture, rectovaginal fistulas, and genital elephantiasis, occur in women
•Tetracycline is recommended for treatment of acute lymphogranuloma venereum |
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Definition
•Rickettsiae are small, Gram-negative coccobacillary bacteria that are obligate, intracellular pathogens that reside in animals and insects and do not require humans for perpetuation
•Humans are accidental hosts for most species of Rickettsia and the target is the endothelial cell of the capillaries and other small blood vessels where they reproduce within these cells, killing them in the process and producing a necrotizing vasculitis
•Human rickettsial infection results from insect bites
•Several species of Rickettsia cause different human diseases but rickettsial infections have many features in common |
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Term
| ROCKY MOUNTAIN SPOTTED FEVER |
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Definition
•An acute, potentially fatal, systemic vasculitis usually manifested by headache, fever, and rash
•Caused by Rickettsia rickettsii, which is transmitted to humans by tick bites
•In the United States, most cases occur in a large cluster of states extending from the eastern seaboard (Georgia to New York) westward to Texas, Oklahoma, and Kansas
•Vascular lesions are found throughout the body and affect the capillaries, venules, arterioles, and sometimes, larger vessels, often associated with thrombosis of the smaller-caliber vessels
•Rash of Rocky Mountain spotted fever begins as a maculopapular eruption, but it rapidly becomes petechial, spreading centripetally from the distal extremities to the trunk
•If untreated, more than 20% to 50% of infected persons die
•Prompt diagnosis and antibiotic treatment is lifesaving
•Mortality rate has been reduced to less than 5% in the US |
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Definition
| •Smallest free-living prokaryotes that causes mycoplasma pneumoniae |
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Definition
•Acute, self-limited, lower respiratory tract infections (tracheobronchitis and pneumonia)affecting mostly children and young adults
•Most infections occur in small groups of persons who have frequent close contact, such as families, college fraternities, military units, and residents of closed institutions
•Organism is spread by aerosol transmission over a period of several months
•Infection occurs worldwide, and in developed countries, and the organism causes 15% to 20% of all pneumonias
•Usually shows patchy consolidation of a single segment of a lower lung lobe
•Alveoli display a largely interstitial process, with reactive alveolar lining cells and infiltration by mononuclear cells
•Pneumonia tends to be milder than other bacterial pneumonias "walking pneumonia"
•Death from M. pneumoniae infection is rare, and the infection itself is treated with tetracycline or erythromycin |
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Definition
•Mycobacteria are distinctive organisms that share the cell wall architecture of Gram-positive bacteria
•Grow more slowly than other pathogenic bacteria, and mycobacterial diseases are all chronic, slowly progressive illnesses |
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Definition
•A chronic, communicable disease caused principally by Mycobacterium tuberculosis hominis (Koch bacillus) but also occasionally by M. tuberculosis bovis
•Lungs are the prime target, but any organ may be infected |
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Definition
•Of more than 100,000 known fungi, only a few invade human tissue, and of these, most are opportunists, i.e. infect only persons with impaired immune mechanisms
•Corticosteroid administration, antineoplastic therapy, and congenital or acquired T-cell deficiencies all predispose to mycotic infections |
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Definition
| Aspergillus species are common environmental fungi that produce opportunistic infections, usually involving the lungs |
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Definition
by far the most frequent human pathogen
•Aspergillus is present throughout the world, growing as saprophytes in soil, decaying plant matter, and dung
•Pulmonary aspergillosis is acquired by inhalation of environmental organisms
•Fungus reproduces by releasing numerous small spores, known as conidia, that are carried in the air and into almost every human environment |
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Definition
•Cryptococcosis is a systemic mycosis caused by Cryptococcus neoformans that principally affects the lungs and meninges
•Main reservoir for the fungus is pigeon droppings
•Inhaled organisms penetrate to the terminal bronchioles
•Cryptococcosis almost exclusively affects persons with impaired cell-mediated immunity, including patients with AIDS, lymphomas, Hodgkin's disease, leukemias, and sarcoidosis and patients receiving high doses of corticosteroids
•More than 95% of cryptococcalinfections involve the meninges and brain
•Lesions in the lungs can be demonstrated in half the patients as diffuse disease or as isolated areas of consolidation
•In cryptococcal meningoencephalitis, the entire brain is swollen and soft, and the leptomeninges are thickened and gelatinous owing to infiltration by the thickly encapsulated organisms
•Untreated cryptococcal meningitis is invariably fatal, and therapy requires prolonged, systemic administration of antifungal medication |
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Definition
| extracellular parasites capable of digesting and invading human tissues |
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Definition
| obligate, intracellular parasites that replicate within human cells, thereby killing them |
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Definition
| damage human tissue largely through the inflammatory and immunologic responses they incite |
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Definition
| have the capacity to establish latent infections and produce reactivation disease among immunosuppressed hosts |
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Definition
•Caused by Toxoplasma gondii
•Most infections are asymptomatic, but when they occur in the fetus or an immunocompromised host, devastating necrotizing disease may result
•In some areas (e.g., Paris), the prevalence of T. gondii infection exceeds 80% of adults, whereas in other (e.g., the southwestern part of the United States), only a small portion of the population is infected
•Toxoplasma gondii infects the cat's intestinal epithelium |
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Definition
•Infection with T. gondii in a fetus is much more destructive than in a child or adult
•Developing brain and eyes are readily infected, and the fetus lacks the immunologic capacity to contain the infection
•Central nervous system infection produces a necrotizing meningoencephalitis, which, in the most severe cases, results in the loss of brain parenchyma, cerebral calcifications, and marked hydrocephalus
•Ocular infection causes chorioretinitis (necrosis and inflammation of the choroid and retina) |
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Term
| Toxoplasmosis in Immunocompromised patients |
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Definition
•Devastating T. gondii infections occur in persons with decreased cell-mediated immunity (e.g., patients with AIDS or those immunosuppressed for transplantation)
•In most cases, the disease represents a reactivation of latent infection
•In the brain, which is the most commonly affected organ, infection with T. gondii produces a multifocal necrotizing encephalitis |
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Definition
•Megaesophagus(dilatation of the esophagus caused by failure of the lower esophageal sphincter (achalasia) is a common complication of chronic Chagas disease
•Results from the destruction of parasympathetic ganglion cells in the wall of the lower esophagus
•Megacolon (massive dilatation of the large bowel) is similar to megaesophagus in that the myenteric plexus of the colon is destroyed
-Progressive aganglionosis of the colon causes severe constipation
•Antiprotozoal chemotherapy is effective for acute Chagas disease but is of no value for the chronic sequele |
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Term
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Definition
•An inflammatory, parasitic infestation of lymphatic vessels caused by the filarial roundworms Wuchereria bancrofti and Brugia malayi
•Adult worms inhabit the lymphatics, most frequently those in the inguinal, epitrochlear, and axillary lymph nodes, testis, and epididymis
•Causes acute lymphangitis and eventual lymphatic obstruction, leading to massive lymphedema of the affected tissues (elephantiasis)
•Humans can acquire infection from the bites of at least 80 species of mosquitoes in southern Asia, the Pacific, Africa, and portions of South America
•Diethylcarbamazine is the current chemotherapeutic agent of choice against lymphatic filariasis |
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Term
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Definition
•Most important helminthic disease of humans
•Intense inflammatory and immunologic responses damage the liver, intestine, or bladder
•Three are three species of schistosomes are responsible for the disease: Schistosoma mansoni, S. hematobium, and S. japonicum
•Schistosomiasis causes greater morbidity and mortality than all other worm infestations, and it ranks second only to malaria as a cause of disabling disease and death
•A schistosome egg hatches in fresh water, liberating a motile form (miracidium) that penetrates a snail, in which it develops to the final larval stage, the cercaria
•Cercaria escapes from the snail into the water and then penetrates the skin of the human host
•In the intestinal venules of the portal drainage, the organisms mature
•Female S. mansoni and S. japonicum deposit immature eggs in the intestinal venules, whereas female S. haematobium lay eggs in those of the urinary bladder
•Basic lesion is a circumscribed granuloma or a cellular infiltrate of eosinophils and neutrophils around an egg |
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Term
| S. mansoni or S. japonicum |
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Definition
•Liver disease caused by S. mansoni or S. japonicum begins as periportal granulomatous inflammation and progresses to dense periportal fibrosis (pipestem fibrosis)
•In severe cases of hepatic schistosomiasis, obstruction of the portal blood flow and portal hypertension, splenomegaly, ascites, and bleeding esophageal varices may ensue |
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Term
| Urogenital schistosomiasis |
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Definition
•Caused by S. haematobium, features eggs that are most numerous in the bladder
•Schistosomiasis of the bladder causes hematuria, recurrent urinary tract infections, and sometimes, progressive obstructive damage leading to renal failure
•Bladder schistosomiasis by S. haematobium is related to the development of squamous cell carcinoma of the bladder
•Schistosomiasis is effectively treated with systemic anthelminthic agents |
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