17 terms

Blood and Tissue Parasitology

Protozoa that can cause blood and tissue infections
What are the parasitic forms of Trypanosoma Leishmania? Which ones are found in humans?
amastigotes (human liver cells)
trypomastigotes (human plasma)
What is the vector of Chagas' disease, it's resevoir and where in the world is it found? What is the pathogenesis?
aka American trypanosomiasis
T.cruzi - reduviid bug
zoonotic - animal resevoirs
South/Central America
bug feces in face or eyes -> infects local tissue and causes ulcer -> inflammatory response obstructs lymphatics -> local edema (Romana's sign) -> local lymph enlargens and blood invaded -> spread through RES and localizes in myocardium and GIT and neuroglial cells
What is the vector and host for Leishmaniasis?
vector: phlebotomine sandfly
hosts: rodents, dogs, humans, etc.
What are the 4 basic forms of Leishmaniasis?
Diffuse cutaneous
Visceral Leishmaniasis (aka 'kala azar') L. donovani
most severe form, 100% fatality if untreated
Characterized by irregular fever, marked weight loss, anemia, hepatosplenomegally
amastigotes in liver, spleen, bone marrow
Parasite localization in macrophages of reticuloendothelial system -> pancytopenia -> high output heart failure (myocarditis/percarditis)
replicate in RES
asymptomatic or subclinical or acute, subacute, or chronic
classical: pt life threatening, incubation period of weeks to months, fever, marked cachexia, hepatosplenomegaly, pancytopenia, hyperhammaglobulinemia with hypoalbuminemia
diagnosis: presentation, history of exposure, parasite demonstration
treatment: penotsan, glucantine, allopurinol, miltefosine
Entamaeba histolytica
worldwide dist. 3rd
poor sanitation
increasing among homosexuals
AIDS pt susceptible
resistant to chlorine
intestinal disease -> extraintestinal spread -> liver abscess -> rupture -> pericardial disease
Tissue sporozoa
Toxoplasma gondii (disease, hosts, modes of infection, disease cycle)
Cat family - definitive host
Many vertebrates - intermediate host
Modes of infection: undercooked meat; fecal-oral tranmission via cat feces; organ transplant; blood xfusion; transplacental transmission
Infection -> usually subclinical -> flu-like, if clinical -> latency -> reactivation if compromised -> encephalitis, chorioretinitis, myocarditis, pericarditis, congestive heart failure
Which intestinal parasites may be associated with myocarditis, pericarditis, pericardial effusions or cardiac tamponade
Trichinella spiralis (trichinosis) - striated muscle, even heart
Echinococcus granulosus (hydatid cysts)
Taenia solium (cysticercosis)
Which metazoa cause severe anemia and may cause severe cardiac pathology?
Necator americanus
Acylostoma duodenale
Diphyllobothrium latum
Which nematodes cause filariasis?
Wuchereria bancrofti (Human)
Brugia malayi (Zoonotic)
Onchocerca volvulus
Loa loa
Dracunculus medinensis
Elephantitis (epidemiology, pathogenesis, early and late pathology, diagnosis and treatment)
epidemiology: 120 million affected, 40 million disfigured, mostly in the tropics and subtropics, spread by mosquito, slow developing chronic disease, primarily human disease
pathogenesis: microfilarie from mosquito -> adult worm in lymphatics -> production of many microfilariae -> lymphoedema -> inflamm rxn -> elephantiasis
early path: acute inflamm; hypereosinophilia; massive lymphatic dilatation; bacterial and fungal infections; roll of Wolbachia bacteria
late path: lymphoedema/elephantiasis; chyluria - lymph in urine
diagnosis: exposure; physical presentation; inc. eosinophils; inc. IgE; inc. specific antifilarial Ab; inc. IgG4; microfilariae in blood (nocturunal periodicity); circulating antigen detection (ELISA, card test)
treatment: Antihelminthics: diethylcarbamazine (DEC), albendazole + DEC, albendazole + ivermectin; Antibacterials: Wolbachia g- bacteria coexist with worms contribute to pathology, kill with tetracycline, rifampicin or doxycycline.
Onchocerciasis/River Blindness (epidemiology, mode of infection, pathogenesis, diagnosis, treatment)
epidemiology: blindness; 18 mil mostly Africa and S.A.; non-fatal; rapidly disappearing with WHO programs
Mode of Infection: bite by black fly -> larvae injected, mature in subcut tissue -> adult in nodules -> microfilariae released, migrate to skin and eyes
Pathogenesis: adult in onchocercoma -> millions of migrating microfilariae -> death of microfilariae -> CMI/Ab response/inc. IgE -> onchodermatitis (rough skin) + keratitis (may cause blindness)
Diagnosis: history of exposure - black flies lay eggs in fast flowing rivers; clinical persentation; microfilariae in skin snip, slit lamp biomicroscopy
Treatment: Diethycarbamazine; Ivermectin; Suramin (Antrypol)
Loa Loa (epidemiology, vector, pathogenesis, diagnosis, treatment
epidemiology: loiasis (Calabar swellings), limited dist - West Africa, Chrysops fly (deerfly), co-infected with other filaria
Pathogenesis: bite of fly -> infective larvae -> subdermal CT -> moves around fascia of skin -> mature into adults -> swllings due to migrating worms -> across eye -> immune rxn to migrating (swellings and cysts) and dead worms (chronic abscesses followed by granuloma formation and fibrosis)
Diagnosis: microfilariae in blood (diurnal periodicity), adult worm across eye, antigen detection
Treatment: Ivermectin; albendazole
Dracunculiasis Mendinensis (Vector, hosts, diagnosis, treatment, control/eradication)
Vector: Cyclops (water flea)
Nautral infxn of many animals
larval stage in cyclops (vector)
Adult stage in vetebrates; infection from larvae in contaminated water -> develop to adult in subcut tissue -> debilitating skin eruptions
Diagnosis: radiology; direct visualization
Treatment: metronidazole; thiabendazole
Control/Eradication: water treatment - filtration, boiling
Mansonella Ozzardi (distribution, vectors, symptoms)
Distribution: South America & Caribbean
Vectors: Simulium black fly & Culicoides midges
Symptoms: mild/asymptomatic - headache, jonit pains, pruritus, inguinal adenitis possible