Parasitology Flashcards
Organism responsible for watery, foul smelling, greenish vaginal discharge accompanied by itching and burning Strawberry cervix
Trichomonas vaginalis
Most common cause of chronic diarrhea in patients with HIV
Cryptosporidium parvum
Only ciliated protozoan to cause human disease and what is this disease?
Balantidium coli Balantidial dysentery
Most common tapeworm in developed countries Has polar filaments and six-hooked larva
Hymenolepsis nana
Province in Mindanao not affected by Schistosomo japonicum
Misamis Oriental
Intermediate host of Schistosoma japonicum
Snail Oncomelania hupensis quadrasi
Intermediate host of Paragonimus Westermani
Snail (Antemelania asperata) Mountain crab (Sundathelphusa philippina)
Most common and largest intestinal nematode Sometimes referred to as pencil size worm
Ascaris lumbricoides
What is the common and scientific name of the organism that cause pruritus of scalp or trunk; nits seen on hair shaft?
Lice (Pediculus humanus)
What is the common and scientific name of the organism that cause pruritus in pubic area; nits seen on hair shaft?
Lice (Phthirus pubis)
What is the common and scientific name of the organism that cause pruritic, painful, and erythematous nodule; larva may be seen emerging from nodule?
Flies (Dermatobia hominis)
What is the common and scientific name of the organism that cause pruritic, erythematous wheal?
Bedbugs (Cimex lecturalius)
What is the common and scientific name of the organism that cause pruritic, erythematous papules, and linear tracks
Mites (Sarcoptes scabei)
What is the common and scientific name of the organism that cause ascending paralysis?
Ticks (Dermacentor)
Zoonotic roundworms Ingested in raw seafood Causes eosinophilic gastroenteritis
Anisakis simplex
Most common cause of parasitic meningitis Eosinophilic meningitis Transmitted in undercooked seafood
Angiostrongylus cantonensis
Dog and cat hookworm that cause creeping eruptions (cutaneous larva migrans)
Ancylostoma caninum Ancylostoma braziliense
Visceral larva migrans Ocular larva migrans Uveitis Endophthalmitis
Dog ascaris (Toxocara canis)
Transmitted when copepods are swallowed in water Findings: Live worm in skin ulcer and pruritic painful papule
Guinea fire worm (Dracunculus medinensis)
Characterized by Subcutaneous edema (Calabar swellings) Worm crawling across the conjunctiva
Loa loa
Findings: Dermal nodules Hanging groin Lizard skin River blindness
Onchocera volvulus (Transmitted by female blackfly)
Process of living together of 2 unlike organisms
Symbiosis
One species benefits without harming/ benefiting the other
Commensalism
Both species benefit one another
Mutualism
One species benefits while harming the other
Parasitism
Lives inside the body of the host Presence in host connotes infection
Endoparasite
Lives outside the body of the host Presence in host connotes infestation
Ectoparasite
Needs a host at some stage of their life cycle to complete development and propagation
Obligate parasite
May exist in a free-living state but becomes parasitic when the need arises
Facultative parasite
Establishes itself in a host it does not ordinarily live in/on
Accidental or Incidental parasite
Remains on host for life
Permanent parasite
Lives on host for short period of time
Temporary parasite
Free living organism that passes through digestive tract without infecting the host
Spurious parasite (Technically not a parasite kasi dumaan lang pero wala namang ginawa sa host)
Parasite attains sexual maturity here
Definitive or Final host
Organism that harbors the asexual or larval stage
Intermediate host
Parasite that does not develop further to later stages
Paratenic host
Allows life cycle to continue and become additional sources of human infection
Reservoir host
Transmits parasites from one host to another
Vector
Transmits parasite only after it has completed its development
Biologic vector
Only transports the parasite
Mechanical or Phoretic Vector
Process of inoculating an infective agent
Exposure
Establishment of infective agent inside host
Infection
Between infection and evidence of symptoms
Incubation period (Clinical)
Between infection and demonstration of infection
Pre-patent period (Biological)
Infected individual becomes his own direct source of infection
Autoinfection
Infected individual is further infected with same species leading to massive infection
Hyperinfection or Superinfection
Eukaryotic organism that lacks membrane-bound organelles Exhibits Brownian movement
Entamoeba histolytica (Brownian movement - Pseudopod-forming nonflagellated protozoa
Trasmission: Fecal-oral route Infective stage: Mature cyst Diagnostic stage: Trophozoites, mature cysts, immature cysts
Entamoeba histolytica
Pathogenesis Lectin mediates adherence Amebapores used for penetration Cysteine proteases for cytopathic effect
Entamoeba histolytica (Cytopathic effect - cellular destruction)
What is the most common extraintestinal form of Entamoeba histolytica?
Amebic liver abscess
Could present with Dysentery without fever Flask shaped colon ulcers Cyst carrier state Amebic colitis Ameboma Anchovy sauce-like aspirate
Entamoeba histolytica (Ameboma - associated with dysentery) (Anchovy sauce-like aspirate - Amebic liver abscess)
Treatment for 1) Amebic cyst carrier state 2) Amebic colitis 3) Amebic liver abscess
1) Diloxanide furoate 2) Metronidazole 3) Metronidazole or percutaneous draingae for nonresponders
Transmission: Fecal-oral route Infective: Cyst Diagnostic: Trophozoites, Cysts
Giardia lamblia
Falling leaf motility Covered with variant surface proteins Flagellate that lives in the duodenum, jejunum and upper ileum
Giardia lamblia
Pathogenesis Leads to enterocyte apoptosis Villous flattening Crypt hypertrophy Disruption of cytoskeleton Adhesive disc and lectin facilitates attachments
Giardia lamblia
Acutely presents with excessive flatus that smells of rotten eggs Chronically presents with steatorrhea, constipation and weight loss What is the organism and treatment?
Giardia lamblia Metronidazole (Steatorrhea - malabsorption)
Undergoes Shizogony and Gametogony Acid-fast organism Opportunistic intestinal protozoa
Cryptosporidium parvum
What organism is the most common cause of diarrhea in patients with HIV?
Cryptosporidium parvum
Transmission: Fecal-oral route Infective: thich-walled oocytes Diagnostic: thick-walled oocytes
Cryptosporidium parvum
Usually is a self-limited non bloody diarrhea but can be life threatening if CD4 < 200 What organism causes this and what’s the treatment?
Organism: Cryptosporidium parvum Treatment: Nitazoxanide (Life threatening due to autoinfection)
It is a urogenital protozoan Exists only as a trophozoite It is pear shaped and flagellated
Trichomonas vaginalis
Transmission: sexual intercourse, “Ping-pong” Infective: trophozoite Diagnostic: trophozoite
Trichomonas vaginalis
What is the disease and organism that cause: Watery, foul-smelling, greenish vaginal discharge accompanied by itching and burning Punctate hemorrhages in the cervix? And what is the treatment?
Trichomoniasis caused by Trichomonas vaginalis (Punctate hemorrhage: strawberry cervix) Treatment: Single oral dose of 2 grams (four 500mg tabs) of Metronidazole
Most important parasitic disease in man
Plasmodium
Transmission: bite of infected female mosquito Infective: Sporozoite Diagnostic: Trophozoites (ring forms on RBC)
Plasmodium
What do you call the mosquito responsible for Plasmodium spread?
Anopheles flavirostis minimus
What organism releases merozoites and splenic sequestration of infected cells from the destruction of RBCs Premonition is seen in individuals who completely recover from the disease
Plasmodium (Premonition: partial immunity)
Asexual cycle: 48 hours Periodicity: Malignant tertian RBC preference: All ages Parasitemia: Highest Merozoites: 0 (zero) Gametocytes: Banana shaped Cerebral malaria: Yes Recrudescence: Yes Relapse: No Drug resistance: Many
Plasmodium falciparum
Asexual cycle: 48 hours Periodicity: Benign tertian RBC preference: Young RBCs Parasitemia: Low Merozoites: 12-24 Gametocytes: Large round Cerebral malaria: No Recrudescence: No Relapse: Yes Drug resistance: Few
Plasmodium vivax
Asexual cycle: 72 hours Periodicity: Benign quartan RBC preference: Old RBCs Parasitemia: Lowest Merozoites: 6-12 Gametocytes: Compact Cerebral malaria: No Recrudescence: Yes Relapse: No Drug resistance: Few
Plasmodium malariae
Asexual cycle: 48 hours Periodicity: Benign tertian RBC preference: Young RBCs Parasitemia: Low Merozoites: 8 Gametocytes: Small round Cerebral malaria: No Recrudescence: No Relapse: Yes Drug resistance: Few
Plasmodium ovale
What do you call the recurrence of symptoms after a temporary abatement (2-4 weeks)?
Recrudescence
What do you call the return of a disease after its apparent cessation (1-6 mos) due to reactivation of hypnozoites
Relapse
How do you diagnose Plasmodium?
Thin and thick smears with Giemsa stain Thick to screen for the presence Thin for species identification (Highest yield when blood samples taken during fever or 2-3 hours after peak)
What do you call punctate granulations present in RBCs and invaded by what organism?
Schuffner dots P. ovale & P. vivax
What do you call coarse granulations present in RBCs and invaded by what organism?
Maurer dots Plasmodium falciparum
What do you call fine dots present in RBCs and invaded by what organism?
Ziemann dots Plasmodium malariae
Presents with: Paroxysmal fever with malaise and bone pains Hemolytic anemia, jaundice, splenomegaly Parasitic pneumonitis Dürck granulomas Blackwater fever Algid malaria
Plasmodium Dürck granulomas (Cerebral malaria) Blackwater fever (Acute renal failure) Algid malaria (Septic shock)
Areas of high endemicity of plasmodium?
Palawan, Kalinga-Apayao, Ifugao, Agusan del Sur
Areas of chloroquine resistance?
Palawan, Davao del Norte, Compostela Valley
Treatment for plasmodium 1) Drug of Choice 2) Chloroquine-resistance 3) Eradication of hypnozoites 4) Severe cases or pregnant
1) Chloroquine 2) Mefloquine + Doxycycline 3) Primaquine 4) Quinidine or Quinine
What drug will you use for prophylaxis: 1) Areas without resistant P. falciparum 2) Areas with chloroquine-resistant P. falciparum 3) Areas with multidrug resistant P. falciparum
1) Chloroquine 2) Malarone or Mefloquine 3) Doxycycline
Terminal prophylaxis of P. vivax and P. ovale infections and alternative for primary prevention
Primaquine
Tissue protozoan Definitive host is the domestic cat Humans and other mammals are intermediate hosts
Toxoplasma gondii
Transmission: Ingestion of cysts in raw meat, contaminated food, transplacentally Infective: Fecal oocytes Diagnostic: Trophozoite (bradyzoites)
Toxoplasma gondii
What are the two types of trophozoites and what they do?
Tachyzoites are rapidly multiplying and CMI limits its spread Bradyzoites are slowly multiplying and important in tissue diagnosis
What is the preferred diagnostic test for Toxoplasma gondii?
IgM antibody
1) Immunocompetent hosts: Heterophil-negative mononucleosis 2) Immunocompromised hosts: Encephalitis 3) Congenital: Abortion, stillbirth, neonatal disease with hydrocephalus, encephalitis, chorioretinitis, and hepatosplenomegaly What causes this and what’s the treatment?
Toxoplasma gondii (Encephalitis: Ring enhancing lesions) (Congenital Toxoplasmosis: Intracranial calcification) Tx: Sulfadiazine plus pyrimethamine
Blood and tissue protozoan Transmitted by reduviid bug Has 4 forms: Amastigote, Promastigote, Epimastigote, Trypomastigote
Trypanosoma cruzi
Transmission: Reduviid bug (Triatoma) bite Infective: Metacyclic trypomastigotes Diagnostic: Trypomastigotes in blood
Trypanosoma cruzi
Myocardial, glial, and reticuloendothelial cells are frequent sites Cardiac muscle is the most frequently and severely affected tissue
Trypanosoma cruzi
Diagnosis done through Stained BMA or muscle biopsy Culture of the organism on special medium Xenodiagnosis
Trypanosoma cruzi (Xenodiagnosis: allowing an uninfected, laboratory-raised reduviid bug to feed onthe patient)
What do you call the disease and organism that presents with the ff and its treatment: Romañas sign Chagoma Fever LAD Hepatosplenomegaly
Acute Chagas’ disease caused by Trypanosoma cruzi Nifurtimox (Romaña’s sign: Periorbital edema Chagoma: Nodule near bite)
What do you call the disease and organism that presents with the ff and its treatment: Myocarditis Megacolon Megaesophagus
Chronic disease caused by Trypanosoma cruzi Nifurtimox (Megaesophagus: achalasia)
Blood and tissue protozoan Has 2 forms: epimastigote, trypomastigote Antigenic variation
Trypanosoma brucei
Transmission: tsetse fly (Glossina) bite Infective: Metacyclic trypomastigotes Diagnostic: Trypomastigotes in blood
Trypanosoma brucei
Spread from the skin through the blood to the lymph nodes and the brain Somnolence progresses to coma due to demyelinating encephalitis Cyclical fever spike
Trypanosoma brucei Cyclical fever spike (every 2 weeks) due to antigenic variation Rhodesian more rapid and fatal than gambian
Indurated skin ulcer Intermittent weekly fever and LAD Winterbottom’s sign Kerandel’s sign Excessive somnolence Mott cells What is the organism and treatment?
Tryponosoma brucei Suramin for blood borne disease Melarprosol for CNS penetration (Winterbottom’s sign: Enlargement of the posterior and cervical LN Kerandel’s sign: hyperesthesia Mott cells: plasma cells with cytoplasmic immunoglobulin globules)
Most common cause of red tide in the Philippines?
Pyrodinium bahamense variety compressum (Dinoflagellate) Algal blooms cause red tide These are flagellated marine protists
Transmission by eating bivalve mollusks and fish. Filter feeders accumulate toxins produced by these organisms and what is the treatment?
Dinoflagellates Gastric lavage with activated charcoal Supportive fluid resuscitation Endotracheal intubation for respiratory failure Neostigmine and edrophonium to improve muscle weakness
Facial paresthesia, total paralysis, respiratory failure. Incubation of 15 minutes What is the toxin and syndrome involved?
Saxitoxin Paralytic syndrome
Facial paresthesia, slurred speech, ataxia, diarrhea. Incubation of 15 minutes.
Brevetoxin Neurotoxic syndrome
Diarrhea, nausea and vomiting, abdominal pain. Incubation of 30 minutes.
Okadaic acid toxin Diarrhetic syndrome
Diarrhea, short-term memory loss, seizures. Incubation of 30 minutes.
Domoic acid toxin Amnesic syndrome
What organism exhibits these and the disease it causes? Free living ameba Associated with keratoconjunctivitis associated with contact lens
Organism: Acanthamoeba castellani Disease: Granulomatous amebic encephalitis
What organism exhibits these and the disease it causes? Free living ameba Acquired while swimming in contaminated pools
Organism: Naegleria fowleri Disease: Primary amebic meningoencephalitis
What is the ONLY ciliated protozoan to cause human disease and what is this disease? Associated with pigs Round based, wide necked intestinal ulcers
Disease: Balantidial dysentery Organism: Balantidium coli
What organism exhibits these and the disease it causes? Ixodes tick bite Intraerythrocytic ring-shaped trophozoites in tetrads in the form of a Maltese cross
Organism: Babesia microti Disease: Babesiosis
What organism exhibits these and the disease it causes? Transmitted by sandfly (Phlebotomus) Infective: promastigotes Can have cutaneous, visceral/ kala-azar, or mucocutaneous manifestations
Organism: Leishmania spp. Disease: Leishmaniasis Treatment: Stibogluconate (antimony compounds)
What organism exhibits these? Coccidial sporozoa Causes diarrhea in immunocompromised patients
Cyclospora cayetanensis & Isospora belli
Intestinal cestodes Differentiated based on scolex and gravid proglottids Transmission: undercooked pork/meat Infective: cysticerci (both), eggs (x) Diagnostic: Gravid proglottids What is the organism?
Taenia spp. X: Taenia Solium
What cestode has 4 suckers, a rostellum and 5-10 uterine branches in gravid proglottids?
Taenia solium
What cestode has 4 suckers, no rostellum and 15-25 uterine branches in gravid proglottids?
Taenia saginata
Minor intestinal damage from adult tapeworms Cystecerci can become SOLs in the brain What is the organism and the treatment?
Taenia spp. Praziquantel
Abdominal pain Weight loss Pruritus ani Intestinal obstruction
Taenia saginata
Mild intestinal symptoms Small infective eggs cross the BBB which can cause seizures (neurocysticercosis) Worms seen in vitreous humor
Taenia solium
Two elongated sucking grooves for attachment Operculated eggs Intermediate hosts: fish and copepods
Diphyllobothrium latum
Transmission: undercooked fish Infective stage: plerocercoid larvae Diagnostic stage: unembryonated egg
Diphyllobothrium latum
What organism causes the ff and what is the treatment? Abdominal pain and diarrhea Megaloblastic anemia due to Vitamin B12 deficiency
Diphyllobothrium latum Praziquantel
Treatment of Taenia spp.
Praziquantel
Has one scolex and three proglottids One of the smallest tapeworms Intermediate host: sheep or man Definitive host: dog
Echinococcus granulosus
Transmission: ingestion of eggs Infective stage: embryonated egg Diagnostic stage: hydatid cyst
Echinococcus granulosus
If the cyst of this organism ruptures, it may cause life-threatening anaphylaxis. Hydatid cysts in the liver, pulmonary cysts, cerebral cysts. What is the organism and what is the treatment?
Echinococcus granulosus Surgical resection Albendazole PAIR procedure (Puncture, Aspiration, Injection, Reaspiration)
Definitive host: foxes Intermediate host: rodents Multiloculated cysts (honeycomb vesicles)
Echinococcus multilocularis
Dwarf tapeworm Mostbcommon tapeworm in developed countries Eggs are directly infectious Polar filaments and six-hooked larva
Hymenolepsis nana
Rat tapeworm Accidental parasite Transmitted by ingestion of insects harboring eggs
Hymenolepsis diminuta
Most common tapeworm of dogs and cats Barrel-shaped proglottids
Dipylidium caninum