GI Parasitology
Amoebas Entamoeba hX - amebiasis Transmission: Contaminated fX/wX (fX-oX); sX Infective stage: X Diagnostic Stage: TX/cX in sX (X successive days) or aX Symptomology: Intestinal - bX diarrhea, abdominal pX and tX Extraintestinal - fX, hX tenderness, anorexia, weight X Serology: EX iX (EIA) kits for E. histolytica aX detection as well as EIA kits for aX detection Can generate abscesses in the X = hX tenderness Tro-fX form and dX form Cyst = tX stage of organism
Amoebas Entamoeba histolytica - amebiasis Transmission: Contaminated food/water (fecal-oral); sexual Infective stage: Cyst Diagnostic Stage: Trophozoite/cyst in stool (3 successive days) or abscess Symptomology: Intestinal - bloody diarrhea, abdominal pain and tenderness Extraintestinal - fever, hepatic tenderness, anorexia, weight loss Serology: Enzyme immunoassay (EIA) kits for E. histolytica antibody detection as well as EIA kits for antigen detection Can generate abscesses in the liver = hepatic tenderness Tro-feeding form and dividing form Cyst = transmission stage of organism
GIARDA = FLIP CARD OVER B - discs that attaches to intestinal wall
B - discs that attaches to intestinal wall
Cyclospora cayetanensis - similar to Cryptosporidium (except X). Outbreaks associated with contaminated fX and vX from CX & SX America. 1ST PICTURE: Infected people shed unX (non-iX; immature) Cyclospora cayetanensis oX in their stool; immature oocysts usually require at least X week under favorable laboratory conditions to sporulate (become infective). An unsporulated oocyst, with undifferentiated cytoplasm, is shown (far left), next to a sporulating oocyst that contains two immature sporocysts 2ND PICTURE: Four Cyclospora oocysts from fresh stool stained using a modified X-X stain. The oocysts are variably X-X (that is, they range from unstained to light X to deep X). Image: CDC (DPDx).
Cyclospora cayetanensis - similar to Cryptosporidium (except larger). Outbreaks associated with contaminated fruit and vegetables from Central & South America. 1ST PICTURE: Infected people shed unsporulated (non-infective; immature) Cyclospora cayetanensis oocysts in their stool; immature oocysts usually require at least 1 week under favorable laboratory conditions to sporulate (become infective). An unsporulated oocyst, with undifferentiated cytoplasm, is shown (far left), next to a sporulating oocyst that contains two immature sporocysts (A). An oocyst that was mechanically ruptured has released one of its two sporocysts (B). One free sporocyst is shown as well as two free sporozoites, the infective stage of the parasite (C). Credit: CDC/DPDM. 2ND PICTURE: Four Cyclospora oocysts from fresh stool stained using a modified acid-fast stain. The oocysts are variably acid fast (that is, they range from unstained to light pink to deep red). Image: CDC (DPDx).
Cystoisospora belli (formerly Isospora belli) In US, usually associated with X patients X oX is diagnostic stage; X-X staining. Infection occurs by ingestion of mX (fully sX) oocysts Would be the fX Go though development - sX and will become iX PICTURE: Immature oocyst of C. belli stained with X-X, showing a single sporoblast. (CDC, DPDx)
Cystoisospora belli (formerly Isospora belli) In US, usually associated with AIDS patients Oval oocyst is diagnostic stage; acid-fast staining. Infection occurs by ingestion of mature (fully sporulated) oocysts Would be the feces Go though development - sporilate and will become infective PICTURE: Immature oocyst of C. belli stained with acid-fast, showing a single sporoblast. (CDC, DPDx)
Cysts and trophozoites are passed in fX (1). Cysts are typically found in fX stool, whereas trophozoites are typically found in dX stool. Infection by Entamoeba histolytica occurs by ingestion of mX cX (2) in fX contaminated food, water, or hands. Excystation (3) occurs in the X intestine and tX (4) are released, which migrate to the X intestine. The trophozoites multiply by binary fission and produce cX (5), and X stages are passed in the feces (1). Cysts can survive days to weeks in the external environment and are responsible for transmission. Trophozoites passed in the stool are rX destroyed once outside the body, and if ingested would not survive exposure to the gastric environment. In many cases, the trophozoites remain confined to the iX lumen (A: noninvasive infection) of individuals who are asymptomatic carriers, passing cysts in their stool. In some patients the trophozoites invade the intestinal mX (B: intestinal disease), or, through the bloodstream, extraintestinal sites such as the liver, brain, and lungs (C: extraintestinal disease), with resultant pathologic manifestations. It has been established that the invasive and noninvasive forms represent two separate species, respectively E. hX and E. dX. These two species are morphologically indistinguishable unless E. histolytica is observed with ingested X blood cells (erythrophagocystosis). Transmission can also occur through exposure to fecal matter during sX contact (in which case not only cysts, but also trophozoites could prove infective). Exist in the X intestine but can become extra intestinal
Cysts and trophozoites are passed in feces (1). Cysts are typically found in formed stool, whereas trophozoites are typically found in diarrheal stool. Infection by Entamoeba histolytica occurs by ingestion of mature cysts (2) in fecally contaminated food, water, or hands. Excystation (3) occurs in the small intestine and trophozoites (4) are released, which migrate to the large intestine. The trophozoites multiply by binary fission and produce cysts (5), and both stages are passed in the feces (1). Cysts can survive days to weeks in the external environment and are responsible for transmission. Trophozoites passed in the stool are rapidly destroyed once outside the body, and if ingested would not survive exposure to the gastric environment. In many cases, the trophozoites remain confined to the intestinal lumen (A: noninvasive infection) of individuals who are asymptomatic carriers, passing cysts in their stool. In some patients the trophozoites invade the intestinal mucosa (B: intestinal disease), or, through the bloodstream, extraintestinal sites such as the liver, brain, and lungs (C: extraintestinal disease), with resultant pathologic manifestations. It has been established that the invasive and noninvasive forms represent two separate species, respectively E. histolytica and E. dispar. These two species are morphologically indistinguishable unless E. histolytica is observed with ingested red blood cells (erythrophagocystosis). Transmission can also occur through exposure to fecal matter during sexual contact (in which case not only cysts, but also trophozoites could prove infective). Exist in the large intestine but can become extra intestinal
Disease: Amebiasis is responsible for approximately X deaths per year, mainly in CXand SX America, AX, and IX; considerable mX Asymptomatic infection: ~X% infections, "lX amebiasis", E. dX Invasive intestinal amebiasis: dX, cX, aX, toxic mX, aX Invasive extraintestinal amebiasis: lX abscess, pX, pX abscess, cX and gX amebic lesions Primarily in tX areas Millions who are infected MOST are aX
Disease: Amebiasis is responsible for approximately 100,000 deaths per year, mainly in Central and South America, Africa, and India; considerable morbidity. asymptomatic infection: ~90% infections, "luminal amebiasis", E. dispar invasive intestinal amebiasis: dysentery, colitis, appendicitis, toxic megacolon, amebomas invasive extraintestinal amebiasis: liver abscess, peritonitis, pleuropulmonary abscess, cutaneous and genital amebic lesions Primarily in tropical areas Millions who are infected MOST are asymptomatic
Entamoeba histolytica - amebiasis FLIP CARD OVER ON THE L: Cyst of E. histolytica/E. dispar in an unstained concentrated wet mount of stool. Notice the chromatoid bodies with blunt, rounded ends (arrow). MIDDLE: Cyst of E. histolytica/E. dispar in a concentrated wet mount stained with iodine. Notice the chromatoid body with blunt, rounded ends (arrow). ON THE R: Cyst of E. histolytica/ dispar stained with trichrome. Two nuclei are visible in the focal plane (black arrows), and the cyst contains a chromatoid body with typically blunted ends (red arrow).
Entamoeba histolytica - amebiasis ON THE L: Cyst of E. histolytica/E. dispar in an unstained concentrated wet mount of stool. Notice the chromatoid bodies with bX, rX ends (arrow). MIDDLE: Cyst of E. histolytica/E. dispar in a concentrated wet mount stained with iodine. Notice the chromatoid body with bX, rX ends (arrow). ON THE R: Cyst of E. histolytica/ dispar stained with trichrome. Two nuclei are visible in the focal plane (black arrows), and the cyst contains a chromatoid body with typically bX ends (red arrow).
Free-living opportunistic amoebas Acanthamoeba ImmunoX patient - causes skin uX, pX, fatal eX, GX Amebic EX UX kX in healthy people associated with contaminated cX lX solutions --Unsterile cX lX solution X inflammation due to Acanthamoeba keratitis. This can resemble keratitis caused by hX sX
Free-living opportunistic amoebas Acanthamoeba Immunocompromised patient - causes skin ulcerations, pneumonitis, fatal encephalitis, Granulomatous Amebic Encephalitis Ulcerative keratitis in healthy people associated with contaminated contact lens solutions Early inflammation due to Acanthamoeba keratitis. This can resemble keratitis caused by herpes simplex.
WHAT IS THE MOST COMMON INTESTINAL PROTOZOAN DIAGNOSED IN UNITED STATES?
GIARDIA LAMBLIA
Giardia lamblia FX - X common intestinal protozoan diagnosed in U.S. Transmission - Contaminated fX water (lX & sX - aX reservoir); fX Infective stage - X Diagnostic Stage - TX/cX in sX; gX, fX-smelling stools Disease - mX, dX, weight X, X-soluble vitamin deficiency Giardia - fX Intense dX caused by mX of food Discs block aX of food - passes into the X intestine = dX --Disc is used to aX Flagella Two nuclei
Giardia lamblia Flagellate - most common intestinal protozoan diagnosed in U.S. Transmission - Contaminated fresh water (lakes & streams - animal reservoir); food Infective stage - Cyst Diagnostic Stage - Trophozoite/cyst in stool; greasy, foul-smelling stools Disease - malabsorption, diarrhea, weight loss, fat-soluble vitamin deficiency Giardia - flagellate Intense diarrhea caused by malabsorption of food Discs block absorption of food - passes into the large intestine = diarrhea --Disc is used to attach Flagella Two nuclei
PICTURES - FLIP CARD OVER Inside of the lumen of the intestinal wall with absceses
Inside of the lumen of the intestinal wall with absceses
Intestinal Coccidia All cause dX disease - acquired by ingestion of contaminated fX/wX - infect iX eX Cryptosporidium - major X-borne outbreaks; wX, community swimming pools, and day care centers; associated also with fX aX as reservoir. X-X oX is infectious stage and diagnostic stage Resistant to cX Very difficult to treat in X patients Xcellular parasites - invade eX cells of the intestinal lining Related to mX SX POOLS - water parks AX run off into community supplies = outbreak Removed by X
Intestinal Coccidia All cause diarrheal disease - acquired by ingestion of contaminated food/water - infect intestinal epithelium Cryptosporidium - major water-borne outbreaks; waterparks, community swimming pools, and day care centers; associated also with farm animals as reservoir. ACID-FAST oocyte is infectious stage and diagnostic stage Resistant to chlorination Very difficult to treat in AIDS patients Intracellular parasites - invade epithelial cells of the intestinal lining Related to malaria SPLASH POOLS - water parks Argicultural run off into community supplies = outbreak Removed by FILTRATION
PICTURES - FLIP CARD OVER Liver with abscesses
Liver with abscesses
Naegleria fowleri: "bX-eating ameba" Acquired by swimming in contaminated X fX water. Causes fX primary amebic mX Symptoms can be mild at first, worsen qX. Usually start about X days after infection (range X-X days) hX, fX, nausea, or vomiting Later symptoms can include stiff nX, cX, lack of aX to people and surroundings, loss of bX, sX, and hX After symptoms start, the disease causes death within about X days (range X-X days). Of 133 people known to be infected in the U.S. since 1962, only X people survived. Inhale the organism though X passage and it gets into the bX People die within X week of the infection
Naegleria fowleri: "brain-eating ameba" Acquired by swimming in contaminated warm fresh water. Causes fatal primary amebic meningoencephalitis. Symptoms can be mild at first, worsen quickly. Usually start about 5 days after infection (range 1-9 days) headache, fever, nausea, or vomiting Later symptoms can include stiff neck, confusion, lack of attention to people and surroundings, loss of balance, seizures, and hallucinations After symptoms start, the disease causes death within about 5 days (range 1-12 days). Of 133 people known to be infected in the U.S. since 1962, only three people survived. Inhale the organism though nasal passage and it gets into the brain People die within 1 week of the infection
Entamoeba histolytica - amebiasis FLIP CARD OVER Trophozoite of E. histolytica/E. dispar in a direct wet mount stained with iodine. Trophozoites of E. histolytica with ingested erythrocytes stained with trichrome. The parasites above show nuclei that have the typical small, centrally located karyosome, and thin, uniform peripheral chromatin.
ON THE L: Trophozoite of E. histolytica/E. dispar in a direct wet mount stained with iX ON THE R: Trophozoites of E. histolytica with ingested eX stained with trichrome. The parasites above show nuclei that have the typical Xl, cX located kX, and tX, uX pX chromatin.
Other Intestinal Protozoa Balantidium coli - Only cX protozoan known to cause human disease - pathology is similar to EX hX - dX, but little possibility of iX. X are main reservoir. Diagnosis: X in stool specimens. Infective stage: X ARE THERE Extra-intestinal STAGES? Tropho - differentiates into a cyst - cyst is the X stage FLIP CARD FOR PICTURES
Other Intestinal Protozoa Balantidium coli - Only ciliate protozoan known to cause human disease - pathology is similar to Entamoeba histolytica - dysentery, but little possibility of invasion. Swine are main reservoir. Diagnosis: trophozoites in stool specimens. Infective stage: cysts. WITHOUT extra-intestinal stages Tropho - differentiates into a cyst - cyst is the non-dividing stage FLIP CARD FOR PICTURES
Parasitic Protozoa X-celled, eX organisms Intestinal and urogenital protozoa Amoebas Giardia lamblia Trichomonas vaginalis -FX Cryptosporidium parvum Cyclospora cayetanensis Cystoisospora belli --CX Balantidium coli
Parasitic Protozoa One-celled, eukaryotic organisms Intestinal and urogenital protozoa Amoebas Giardia lamblia Trichomonas vaginalis -Flagellates Cryptosporidium parvum Cyclospora cayetanensis Cystoisospora belli --Coccidia Balantidium coli
GIARDA = FLIP CARD OVER Physically prevent the villi from uptaking food
Physically prevent the vX from uptaking food
Trichomonas vaginalis Common, X transmitted fX Transmission - Since there is no X form, usually transmitted by iX contact (X survive no more than X hours) Disease - vX irritation; bX, pX, fX discharge; often asymptomatic in X Diagnosis - detection of tX in vX secretions, uX sediment, pX fluid. Transmitted in vX form - X Not from toilet seats - ONLY X contact
Trichomonas vaginalis Common, sexually transmitted flagellate Transmission - Since there is no cyst form, usually transmitted by intimate contact (trophozoites survive no more than 24 hours) Disease - vaginal irritation; burning, purulent, frothy discharge; often asymptomatic in men. Diagnosis - detection of trophozoites in vaginal secretions, urine sediment, prostatic fluid. Transmitted in vegetative form - trophozoite Not from toilet seats - ONLY direct contact