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92 Cards in this Set
- Front
- Back
Routes for CNS infection
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Hematogenous spread (arterial as well as retrograde venous spread, i.e. from face)
Direct implantation (i.e. traumatic) Local extension (i.e. sinuses, osteomyelitis, tooth abscess) Transport along peripheral nerves (i.e. rabies, herpes zoster) |
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Sites of CNS infection
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Meningitis – inflammatory process of leptomeninges and cerebrospinal fluid (CSF)in the subarachnoid space
Meningoencephalitis – inflammation of the brain parenchyma also occurs Focal suppurative infections (i.e. brain abscess) |
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Mechanisms of CNS injury from infection
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Direct cellular injury by the infectious agent
Indirect injury by microbial toxins, inflammatory response or immune-mediated response |
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Some common bacterial causes of meningitis
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Neonates - E. coli, group B steptococci
Streptococcus pneumoniae Listeria monocytogenes in older individuals Neisseria meningitidis in adolescents |
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Some causes of chronic bacterial meningitis
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Tuberculosis
Neurosyphilis (T. pallidum) Lyme disease (Borrelia species) |
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What disease?
Headache, neck pain/stiffness, photophobia, irritability, decreasing level of consciousness, fever |
bacterial meningitis
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What disease?
CSF appears cloudy or frankly purulent shows elevated neutrophil count CSF has increased protein level and decreased glucose level CSF gram stain and culture |
bacterial meningitis
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what cause Waterhouse-Friderichsen syndrome ?
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N. meningitidis
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Most common organisms in Fungal CNS infections
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are Candida albicans, Mucor species, Aspergillus fumigatus and Cryptococcus neoformans
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Most common organisms in Fungal CNS infections in endemic areas?
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Coccidioides immitis, Histoplasmosis capsulatum and Blastomyces dermatitidis
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Fungal CNS infections occurs mainly in who?
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immunocompromised patients
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How Fungal infection spreads?
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Fungal infection spreads to brain by hematogenous route mostly but invasion form sinuses may occur with some species, i.e. Mucor
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Infections occur of skin and mucous membranes in otherwise healthy people but diabetics are more susceptible
Esophagitis is common in AIDS patients Disseminated systemic infection to various sites including brain and meninges may occur in neutropenic patients (leukemia, chemotherapy, bone marrow transplantation) Benign commensals usually, seldom producing severe disease |
Candida
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What is the most common form of human fungal infection?
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C. albicans
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Central nervous system infection usually manifests as _____ and _________
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microabscesses
meningitis |
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candida morphology
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Blastoconidia (budding yeast)
Pseudohyphae – budding yeast cells joined end to end Easily seen on H&E , silver stains (GMS or Gomori methenamin-silver) and PAS (Periodic acid-Schiff) |
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Commonly seen in AIDS, patients on high dose steroids and other immunosuppressed states
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Cryptococcal meningitis
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Environment – soil and bird (especially pigeons) droppings
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Cryptococcal meningitis
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How Cryptococcal meningitis transmitted?
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Infection is through inhalation
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What is the major virulence factor of Cryptococcal meningitis and how it works?
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capsular polysaccharide, glucuronoxylomannin
Inhibits phagocytosis by alveolar macrophages and other inflammatory processes Undergoes phenotypic switching to evade immune responses |
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How Cryptococcus neoformans**** is visualized in CSF?
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5 to 10 um yeast with thick gelatinous capsule
In CSF, cryptococcus visualized in India ink preparations (the thick capsule is seen as a clear halo in a dark background) or an antibody agglutination assay test |
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Cross sections of brain of Cryptococcus neoformans look like:
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“soap bubble “
small cysts due to tissue destruction with spread of organisms along the perivascular space |
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What does Meninges contain of C. neoformans?
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chronic inflammatory cells and fibroblasts with cryptococci
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What occur in immunocompetent individuals as well as suppuration in C. neoformans ?
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Chronic granulomatous inflammation
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How Cryptococci visualized?
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in tissues with mucicarmine, PAS (periodic acid Schiff) or silver stains
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69 year old healthy man with severe headaches for five weeks and sudden hearing loss 4 days prior to admission can caused by what?
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Cryptococcal meningitis
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What is the most common species of fungi that cause disease?
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Aspergillus fumigatus
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What predispose to disease Aspergillus?
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Neutropenia and corticosteroids
RARE IN AIDS pt's |
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Transmission of Aspergillus
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Portal of entry into lungs by inhaling spores which then germinate into hyphae
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Virulence factors of Aspergillus
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adhesins, antioxidants, enzymes and toxins
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Severe invasive infections primarily in the lung but spread hematogenously to brain, heart valves most commonly
Allergic bronchopulmonary in asthma or “fungus ball” (coloniziation of preexisting lung cavity) |
aspergillus
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Gross Morphology of Aspergillus
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Hemorrhagic infarction
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Septate hyphae, 5 to 10 um wide, display acute-angle branching, ~45 degree angle
Angioinvasive Necrotizing inflammation |
Morphology of Aspergillus
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Predisposing factors to infection include neutropenia, corticosteroid use, diabetes mellitus, iron overload and skin breakdown (burns, trauma, surgical wounds, etc.)
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Zygomycosis (Mucormycosis)
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Numerous disease causing species of zygomycetes such as...
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Mucor, Rhizopus,
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transmission of Mucormycosis
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Routes of infection is usually inhalation but may also be ingested or percutaneous exposure
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Three primary sites of invasion of Mucormycosis
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are sinuses, lungs, and gastrointestinal tract
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Occurs in diabetics
Fungus in sinuses invades orbit and brain eating the face off |
Rhinocerebral mucormycoisis
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Gross Morphology of mucormycosis
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Hemorrhagic infarcts
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Nonseptate hyphae, irregularly wide, 6 to 50 um in width, with frequent right angle branching
Angioinvasive Necrotizing inflammation |
mucormycosis
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What region Histoplasma capsulatum endemic?
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Endemic to Ohio, Missouri, and Mississippi River valleys
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Transmission of histoplasma
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Acquired by inhalation of spores in dust from soil contaminated by bird or bat droppings
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Pulmonary infection of Histoplasma resembles what?
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TB, granuloma formation
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Histoplasma infection effect what pt population?
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CNS infection in immunocompromised or have a history suggestive of heavy exposure to histoplasma
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60 yo healthy male who worked in the poultry industry fertilized his garden with chicken feces and had gradually progressive 3 month Hx of headache, N & V, low grade fever, lower extremity weakness. He became unable to walk and had L 6th CN palsy. Bx of lesion
diagnose and treat! |
histoplasmosis. Recovered with amphotericin B and fluconazole
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50 yo healthy woman with several
weeks history of fever, night sweats, weight loss. PE showed weakness of right arm and leg, difficulty walk- ing with a tendency to fall to the left. Initially thought to be metastatic CA. . Lung also showed multiple small bilateral lung nodules. HIV was positive. |
Histoplasmosis resolved with Rx with
Amphotericin B, Itraconcazole and Antiretroviral therapy. |
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Where is Coccidioides immitis endemic?
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Southwest US (particularly Arizona and California’s San Joaquin Valley)
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How is Coccidioides immitis aquired?
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inhalation
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what % of people in endemic areas have positive skin test for Coccidioides immitis ?
And how many develop the actual disease? |
80% and <1% develop the disease
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Morphology: thick double contour wall, size~15 um, broad based buds
May be multinucleated Suppurative granulomas |
Blastomyces Dermatiditis
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What area in tha USA do you find Blastomyces Dermatiditis?
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Central SE USA
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Where do you find Blastomyces Dermatiditis?
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soil
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Trasmission of Blastomyces Dermatiditis
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inhalation or direct inoculation of skin
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Well-circumscribed verrucous ulcerated lesions of facial skin The lesions have irregular raised borders with crusting and purulent discharge.
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Blastomyces
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26 year old with 3 month history of HA fatigue, cough , fever and hemoptysis and spreading facial rash. Empiric Rx with antibiotics. Declin in cognitive funciton. Worked on a farm hit by Katrina. Neuo exam ataxia and L sided weakness and he required 20 to 45 seconds to ansewer quesitons
CXR showed infiltrates. |
Blastomyces
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List Parasites Causing CNS Infection
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Toxoplasma gondii
Plasmodium falciparum Taenia solium Echinococcus granulosis Trypanosoma(T. brucei rhodesiense and T. brucei gambiense) Acanthamoeba Naegleria fowleri |
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How can you get Infection by ingesting Toxoplasma gondii?
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Raw or undercooked meat containing oocysts, particularly pork and lamb
Material contaminated with oocyst containing cat feces – changing litter box |
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los guantes
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gloves
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What is TORCH?
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List that can cross BBB
TO-toxoplasma R-rubella C-CMV H-Herpes |
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Cerebral toxoplasmosis affect what pt population?
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immunocompromised patients, especially AIDS
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Transplacental transmission of toxoplasma can cause what?
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Stillbirth, abortion, microcephalus, hydrocephalus, cerebral calcifications, retinochorditis (most common manifestation)
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Gross Morphology of Cerebral Toxoplasmosis
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Brain abscesses in cerebral cortex near the gray-white junction, deep gray nuclei and rarely other locations
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Acute cerebral toxoplasmosis's micromorphology present with:******
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Central necrosis with tachyzoites and encysted bradyzoites at the periphery of necrotic foci
Surrounding acute and chronic inflammation, macrophages May have vasculitis |
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Which mosquito species causes most severe Malaria?
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Plasmodium falciparum
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List the four main malaria parasites (protozoa)
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Plasmodium vivax
Plasmodium ovale Plasmodium malariae Plasmodium falciparum |
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what is the is the main cause of death due to malaria in children? ******
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Cerebral malaria, caused by P. falciparum,
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T/F
Cerebral malaria is caused by ischemia due to plugging of small blood vessels with parasite laden red cells |
True
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T/F
Plasmodium falciparum causes infected red cells to clump together and to stick to endothelial cells |
True
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Cysticercosis caused by what?
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Taenia solium/Tapeworm
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What routes Taenia solium infects the body?
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. Ingestion of undercooked pork containing larval cysts (cysterci)
Cysterci attach to intestinal wall Adult tapeworms (up to meters in length can then develop) . Ingestion of eggs in contaminated food or water Larvae hatch and penetrate intestinal wall to disseminate hematogenously The larvae encyst in many organs including brain Viable T. solium cyst may not produce symptoms, producing substances which inhibit host defenses When cystercerci die or degenerate, an inflammatory response develops |
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Tanea solium larvea affects mainly what organ in the body?******
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Brain
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What is the most common cause of epilepsy?
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Neurocysticercosis
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What is the Most common neurological infection in the world
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Neurocysticercosis
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What organs does T. Solium infect? List 4 this time!
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brain, muscles, skin and heart but can be found in any organ
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Hydatid disease caused by what?
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Echinococcus
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what is Echinococcus?
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tapeworm
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What animals do you find Echinococcus?
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dogs (E. granulosis) or foxes (E. multilocularis, rare but most virulent)
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Transmission of Echinococcus?
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Ingestion of food (i.e. sheep)contaminated with eggs released by infected dogs (E. granulosis) or foxes (E. multilocularis, rare but most virulent)
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Where does Echinococcus eggs hatch and what organs does it invade?
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Eggs hatch in small intestine and release oncospheres which invade liver, lungs (5-15%), bones and rarely brain
USUALLY SINGLET!!!! |
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Single cyst in the brain
What disease |
Echinococcal cyst (hydatid disease)
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Multiple cysts in the brain.
What disease? |
T. Solium/ Neurocystercicosis
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African trypanosomiasis (sleeping sickness) endmic to what region?
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Sub saharan Africa
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African trypanosomiasis trasmission by what?
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tsetse fly
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What species cause the E. African form of sleeping sickness ?
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T. brucei rhodesiense
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What species cause acute and virulent sleeping sickness? And Where?
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T. brucei rhodesiense
E. Africa |
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What species cause chronic sleeping sickness? And Where?
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T. brucei gambiense
W. Africa |
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How does african trypanosomiasis escape the immune system?
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by antigenic variation of parasite surface glycoproteins
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Symptoms of sleeping sickness
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Intermittent fevers, lymphadenopathy, splenomegaly
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local eye infection by ameba called
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Acanthamoeba
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Where do you find Acanthamoeba?
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water and soil
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CNs infection by Acanthamoeba in immunocomprimissed pt's cause almost always what?
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Death
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What is Naegleria fowleri?
Where do find it? Cause what? |
Free living ameba
Water (lakes, swimming pools, tap water) Immunocompromised primary amebic meningoencephalitis (acute lethal CNS disease) |