Parasitology Flashcards
Causal agent of amebiasis
Entamoeba Histolytica
Protozoa
Amebiasis: bloody diarrhea, liver abscess
Transmission: cyst in the water, fecal -oral
Dx: serology and/or trophozoites with engulfed RBC in the cytoplasm or cyst with up to 4 nuclei in the stool
Tx: metronidazole
Giardiasis
Causal agent : Giardia lamblia
- transmission: fecal oral, cyst in the water.
- diagnosis: multinucleated trophozoites or cyst in the stool
Disease: giardiasis: fatty diarrhea with bloating, flatulence and foul-smelling .
Cryptosporidium
Causal agent of severe diarrhea in AIDS.
Mild disease (watery diarrhea) in inmunocompetent hosts.
Transmission: oocysts in water, undercooked meat
Diagnosis: oocysts on acid fast stain in stool
Tx: prevention , nitozoxanide
Protozoa- CNS INFECTION
- Toxoplasma Gondii
- Naegleria fowleri
- Trypanosoma Brucei
Toxoplasmosis
Toxoplasma gondii
- transmission: cyst in meat, oocysts in CAT feces; transplacentario
- definitive host: cats
- intermediate host: human
- Dx: serology (biopsy) you can see tachyzoite.
- Tx: sulfadiazine + pyrimethamine
Diasease: Toxoplamosis
- after birth: asymptomatic or non-specific flu like illness with fever and lymphadenopathy
- congenital: first trimester : * chorioretinitis * hydrocephalus. * intracranial calcifications
Third trimester : Inapparent, may lead with a progressive blindness in the child later in life (teens)
-Reactivation in AIDS: brain abscess seen as ring-enhancing lesions on MRI. Chronic headaches.
Free living amoebas that occasionally infect humans
- Naegleria fowleri
- Acanthamoeba
Naegleria fowleri
-Disease: rapidly fatal meningoencephalitis
Symptoms: Severe headaches, Nausea, fever, Altered sense of smell .
- Transmission: swimming in fresh water lakes : enters via cribriform plate.
- Diagnosis: * Amoebas in spinal fluids * Motile trophozoites in CSF.
- Treatment : Amphotericin B
Acanthamoeba
Keratitis
Granulomatous amebic encephalitis
- Transmision: free living amebas in contaminated contact lens solution
- Treatment: topical miconazol
Trypanosoma brucei
AFRICAN SLEEPING SICKNESS
- Symptoms: enlarged lymph nodes, recurring fever, somnolence, coma.
- Transmission: tsetse fly bite
- Diagnosis: trypomastigote in blood smear
- Treatment: acute: suramin
Chronic: melarsoprol
Protozoa- hematologic infections
- Plasmodium : vivax/ovale, falciparum, malariae
- Babesia
Babesia
Disease : BABESIOSIS
Fever and hemolytic anemia
Predominant in northeastern of USA
Coinfection with Borrelia (Lyme disease)
- transmission: Ixodes tick bite
- Diagnosis: Blood smear: ring form , Maltese cross , Terras in RBC
Plasmodium
MALARIA
Fever spikes, headache, anemia, splenomegaly. This symptoms appears when merozoites are liberate from RBC.
HbS and other kind of abnormal hemoglobin have resistant to get infect by this Protozoa.
Two phases :
- Sexual in the female mosquito (anopheles): form sporozoites in her stomach, they migrate to salivary glands to infect humans through the bite.
- Asexual phase : in humans, we get the sporozoites from the mosquito bite, they travel in blood to liver cells and transform in trophozoites and then merozoites, causing RBC lysis and merozoites go infected other cells.
Types of plasmodium:
- P. Vivax/ovale: 48hr cycle (tertian) . Diagnosis: schuffner dots in blood smear.
- P. falciparum : 72 hrs cycle (malignant tertian or quartan) : irregular fever spikes, causes cerebral malaria. Diagnosis on blood smear multiple ring forms crescent or banana shaped gametes.
- Treatment: Chloroquine
Protozoa - visceral infection
- Trypanosoma cruzi: Chagas disease
- Leishmania donovani
Leishmania
- L. donovani: visceral leishmaniasis
- L. braziliensis : mucocutaneous leishmaniasis
- Leishmania spp: cutaneous leishmaniasis
Leishmania donovani
VISCERAL LEISHMANIASIS ( kala- azar) - Symptoms: Spiking fever Hepatoesplenomegaly Pancytopenia
- Transmission: sandfly
- Diagnosis: macrophages containing amastigotes
- Treatment: amphotericin B, sodium stibogluconate.
Trypanosoma cruzi
CHAGAS DISEASE (American Trypanosomiasis)
Dilated cardiomyopathy with apical atrophy, megacolon, megaesophagus.
Unilateral peri orbital swelling (romaña sign) characteristic of acute stage.
- Transmission: triatomine bug (reduviid bug) feces, deposited in a painless bite.
- Diagnosis: trypomastigote in blood smear
- Treatment: benznidazole or nifurtimox
Protozoa - sexually transmitted
Trichomona vaginalis
TRICHOMONIASIS
- Vaginitis
- foul-smelling
- greenish discharge
- itching and burning
- Transmission: sexually
- Diagnosis: vaginal discharge, strawberry cervix, trophozoites motile on wet mount
- Diagnosis: metronidazole for patient and partner (prophylaxis)
Nematodes (roundworms)
Routes of infection
- Ingested : Enterobius, Ascaris, Toxocara, Trichinella
- Cutaneous: Strongyloides, Ancylostoma, Necator
- Bites: Loa Loa, Onchocerca volvulus, Wuchereria bancrofti
Enterobius vermicularis (pinworm)
Intestinal infection causing anal pruritus.
- Transmission:fecal oral, auto ingested
- Diagnosis: seeing egg via scotch tape
- Treatment: bendazoles (albendazole), treat all family.
Ascaris lumbricoides
Giant roundworm
Ascariasis: Intestinal infection with possible obstruction at ileocecal valve.
- Transmission: fecal oral, eggs ingested
- Diagnosis: bile stained, knobby eggs, adults 6-12” roundworms
- Treatment: mebendazole, surgery extraction
Strongyloides stercoralis
Threadworms
Strongyloidiasis (may mimic peptic ulcer)
- Early: pneumonitis, abdominal pain, diarrhea
- Later: malabsorption, ulcers, bloody stools
- transmission: filariform larvae in the soil penetrate the skin
- Diagnosis: serology, larvae in stool
- Treatment: Ivermectin or thiabendazole
Hookworms:
- Ancylostoma duodenale
- Necator americanus
Intestinal infection causing anemia by sucking blood from intestinal wall.
Transmission: filariform larvae penetrates intact skin of bare feet
Diagnosis: occult blood may be present, fecal larvae and ova
Treatment: mebendazole and iron therapy
Ancylostoma braziliensis
CUTANEOUS LARVA MIGRANS : pruritic, serpiginous rash from walking barefoot on contaminated beach.
Transmission: filariform larvae penetrate human skin but can not mature due to real host is dogs and cats .
Treatment: topical steroids and thiabendazole or pyrantel pamoate
Trichuris trichiura
Whipworm cecum: appendicitis and rectal prolapse
Transmission: eggs ingested
Diagnosis: barrel-shaped eggs with bipolar plugs in stools
Treatment: albendazole
Trichinella spiralis
TRICHINOSIS
- fever, vomiting, myalgias, periorbital edema
- Pathogenesis: intestinal infection;larvae enter bloodstream and encyst in striated muscle cells causing inflammation of muscle.
- Transmission: viable encysted larvae in meat undercooked are consumed.
- Diagnosis: muscle biopsy
- Treatment: bendazoles
Visceral larva migrans
Toxocara canis
Nematodes migrate to blood through intestinal wall causing inflammation and damage. Organs frequently affected included the heart, liver and CNS.
- Transmission: fecal oral, eggs ingested
- Diagnosis: clinical findings and serology
- treatment : bendazoles
Filarial nematodes
- Onchocerca volvulus: onchocerciasis or river blindness disease, transmitted by female blackfly. Cause skin changes, loss of elastic fibers and blindness . Treatment: ivermectin
- Loa loa: worm in the conjunctiva . Transmitted by deer fly, horse fly or mango fly. Diagnosis: microfilariae in blood, eye and skin swelling. Eosinophilia. Treatment: surgical removal from the eye, but first paralyze with diethylcarbamazine.
- Wuchereria bancrofti: ELEPHANTIASIS: worms invade lymphnodes and cause inflammation, which can block lymphatic vessels. Takes 9months to 1 year to become symptomatic. Transmitted by female mosquito. Diagnosis: microfilariae in blood. Eosinophilia. Treatment: surgery, ivermectin and diethylcarbamazine.
Cestodes ( tapeworms)
- Taenia solium and Saginata
- Diphyllobothrium latum
- Echinococcus granulosus
Taenia solium
Two types of disease, depends in what are you ingested:
- Eggs ingested: Cysticercosis
- Cysticerci: intestinal tapeworm (taeniasis)
Cysticercosis
Eggs of Taenia solium in water, vegetation or food.
Symptoms: seizures, elevated intracranial pressure (ICP), meningoencephalitis, psychiatric disorder, stroke, and/or radiculopathy or myelopathy, if the spinal cord is involved.
Diagnosis: biopsy, MRI
Treatment: praziquantel, corticosteroids in case of cerebral edema and anticonvulsants.
Taeniasis (intestinal tapeworms)
Raw pork containing the Cysticerci is ingested by humans
Symptoms: asymptomatic or vague abdominal pains
Diagnosis: proglottis or eggs in feces.
Treatment: praziquantel
Diphyllobothrium latum (fish tapeworm) 🍣
Transmission: ingestion of larvae from raw freshwater fish.
Treatment: praziquantel
Two diseases:
- Sparganosis: when humans are intermediate hosts, larvae penetrate intestinal wall and encyst. Ingestion of the copepods (crustaceans) carrying the larval forms. Dx: biopsy
- intestinal tapeworm : megaloblastic anemia, definitive host was humans . Dx: proglottids or eggs in feces.
Echinococcus granulosus
Intermediate hosts: herbivores, rare humans
Definitive hosts: Sheep
Transmission: ingestion of eggs from dog feces
Disease: Hydatid cyst : liver and lung cysts
Diagnosis: image, serology.
Treatment: albendazole and surgery
Trematodes
- commonly called flukes
- are hermaphrodite except for schistosoma.
- have operculate eggs which contaminate water.
- the first intermediate host are snails
- Schistosoma mansoni
- Schistosoma haematobium
- Clonorchis sinensis
- Fasciola hepatica
- Paragonimus westermani
Intestinal schistosomiasis
Schistosoma mansoni agent causal
Acquisition: contact with contaminated water. Larvae skin penetration.
Progression: cercariae skin penetration (itching), mature in veins of mesentery, eggs cause granulomas in liver.
Diagnosis: eggs in the stool. Characteristic eggs with lateral spine. Schistosoma haematobium has a terminal spine.
Treatment: praziquantel
Clonorchis sinensis
Common name: Chinese liver fluke
Reservoir host: dogs, cats, humans
Acquisition: raw fish ingestion
Disease: biliary tract inflammation : pigmented gallstones. Associated with cholagiocarcinoma.
Treatment: praziquantel
Diagnosis: opperculated eggs
Ectoparasites
-Scabies (sarcoptes scabiei): mites that burrow into the stratum corneum and cause pruritic. Cause serpiginous burrows in webspace of hands and feet. Transmit by fomites. Treatment: permethrin cream, washing/drying all clothing/bedding.
-Lice ( Pediculus humanus/ phthrius pubis) Lice are ectoparasites that live on the body. Lice feed on human blood after piercing the skin and injecting saliva, which may cause pruritus due to an allergic reaction. Lice crawl but cannot fly or hop.
Lice move from person to person through close physical contact. Spread through contact with fomites (eg, combs, brushes, clothes, hats, scarves, coats, linens) used by an infested person is uncommon. Overcrowding encourages the spread of lice. The body louse can be the vector of Rickettsia prowazeki, which causes typhus; Bartonella quintana, which causes trench fever; and Borrelia recurrentis, which causes relapsing fever.
Biliary tract infection, cholangiocarcinoma
Clonorchis sinensis
Braun cysts and seizures
Neurocysticercosis
Taenia solium
Liver cysts
Echinococcus granulosus
Microcytic anemia
Ancylostoma
Necator
Myalgias, periorbital edema
Trichinella spiralis
Perianal pruritus
Enterobius vermicularis
Portal hypertension
Schistosoma mansoni, Schistosoma japonicum
Vitamin B12 deficiency
Megaloblastic anemia
Diphyllobothrium latum
Only nematode which produce anemia
Necator americanus
Transmission: larvae skin penetration
Opportunistic infections in AIDS
Cryptosporidium
Isospora
Microsporidia
Cyclospora
Pathology of Giardiasis
Giardia lamblia make Pathogenesis with ventral sucking disc. Adherence to the mucosa of the upper small intestine.
