XIV - Parasitology Flashcards
Process of living together of 2 unlike organisms
Symbiosis
One species benefits the other without harming/benefiting the other
Commensalism
Both species benefit one another
Mutualism
One species benefits while harming the other
Parasitism
Parasite lives inside the body of the host
Endoparasite
Parasite lives outside the body of the host
Ectoparasite
Presence of endoparasite in host connotes
infection
Presence of ectoparasite in host connotes
infestation
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
Accidental/Incidental Parasite
Remains on host for life
Permanent Parasite
Lives on host for a short period of time
Temporary Parasite
Free-living organism that passes through digestive tract without infecting the host
Spurious Parasite
Host where parasite attains sexual maturity
Definitive/Final Host
Host that harbors the asexual or larval stage
Intermediate Host
Host wherein the parasite does not develop further to later stages
Paratenic Host
Host that allows the life cycle to continue and become additional sources of human infection
Reservoir Host
Transmits parasite from one host to another
Vector
Transmits parasite only after it has completed its development
Biologic Vector
Vector that only transports the parasite
Mechanical/Phoretic Vector
Process of inoculating an infective agent
Exposure
Establishment of infecting 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
Host Effects: E. histolytica trophozoites secrete cysteine proteases which digest cellular material
Enzymatic Interference
Host Effects: Plasmodium invades RBCs and cause rupture
Invasion & Destruction
Host Effects: D. latum competes with host for available supply of vitamin B12 (pernicious anemia)
Nutrient Deprivation
Immune Invasion: E. histolytica produces suppressor factor that inhibits monocyte movement
Immune Suppression
Immune Invasion: Surface protein variation in T. gambiense
Antigenic Variation
Immune Invasion: E. granulosus carries blood group antigens
Host Mimicry
Immune Invasion: T. gondii multiplies inside macrophages
Intracellular Sequestration
Protozoa: Intestinal Tract
Entamoeba histolytica, Giardia lamblia, Cryptosporidium parvum
Protozoa: Urogenital Tract
Trichomonas vaginalis
Protozoa: Blood & Tissue
Plasmodium, Toxoplasma gondii, Trypanosoma
Pseudopod-forming non-flagellated protozoa (Brownian movement), eukaryotic organism that lacks membrane-bound organelles, simple life cycle
Entamoeba histolytica
Most invasive parasite among the Entamoeba
Entamoeba histolytica
Entamoeba histolytica: Transmission
fecal-oral
Entamoeba histolytica: Infective Stage
mature cysts
Entamoeba histolytica: Diagnostic Stage
trophozoites (acute diarrhea), mature cysts & immature cysts (hardened stool)
Entamoeba histolytica Virulence Factors: Mediates adherence
lectin
Entamoeba histolytica Virulence Factors: Penetration
amebapores
Entamoeba histolytica Virulence Factors: Cytopathic effect
cysteine proteases
Entamoeba histolytica: Diseases
cyst carrier → amebic colitis → ameboma → amebic liver abscess
Entamoeba histolytica Diseases: Dysentery without fever, flask-shaped colon ulcers
amebic colitis
Entamoeba histolytica Diseases: Mass-like lesion in abdomen, associated with dysentery
ameboma
Entamoeba histolytica Diseases: Most common extraintestinal form, anchovy paste-like aspirate
amebic liver abscess
Entamoeba histolytica Treatment: Cyst Carrier State (asymptomatic)
Diloxanide furoate
Entamoeba histolytica Treatment: Amebic Colitis
Metronidazole
Entamoeba histolytica Treatment: Amebic Liver Abscess
Metronidazole, percutaneous drainage for non-responders
Entamoeba histolytica Treatment: Mild to Moderate Infection
Metronidazole + luminal agent
Entamoeba histolytica Treatment: Severe Infection
Metronidazole/Tinidazole + luminal agent
Entamoeba histolytica Treatment: Hepatic Abscess, Extraintestinal Infection
Metronidazole/Tinidazole + luminal agent
Flagellate that lives in the duodenum, jejunum and upper ileum, falling leaf motility, simple asexual life cycles, covered with variant surface proteins
Giardia lamblia
Giardia lamblia: Transmission
fecal-oral
Giardia lamblia: Infective Stage
cysts
Giardia lamblia: Diagnostic Stage
trophozoites (binucleated, “old man”), cysts
Adhesive disc and lectin facilitate attachment to avoid peristalsis, villous flattening, crypt hypertrophy, disruption of cytoskeleton, ultimately leads to enterocyte apoptosis
Giardia lamblia
Abdominal pain, “Backpacker’s Diarrhea”, excessive flatus (rotten eggs)
Acute Giardia lamblia Infection
Giardia lamblia: Chronic Infection
constipation, weight loss, steatorrhea
Giardia lamblia: Treatment
Metronidazole
Opportunistic intestinal protozoa, undergoes schizogony and gametogony, autoinfection in immunocompromised patients, acid-fast organism, simple life cycle
Cryptosporidium parvum
Cryptosporidium parvum: Transmission
fecal-oral
Cryptosporidium parvum: Infective Stage
thick-walled oocysts
Cryptosporidium parvum: Diagnostic Stage
thick-walled oocysts
Self-limited non-bloody diarrhea, severe life-threatening diarrhea if CD4 < 200 due to autoinfection
Cryptosporidium parvum
Cryptosporidium parvum: Treatment
Nitazoxanide
Urogenital protozoan, exists only as a trophozoite, pear-shaped, flagellated trophozoites, simple life cycle
Trichomonas vaginalis
Trichomonas vaginalis: Transmission
sexual intercourse, “Ping-Pong” transmission
Trichomonas vaginalis: Infective Stage
trophozoites
Trichomonas vaginalis: Diagnostic Stage
trophozoites
Watery, foul-smelling, greenish vaginal discharge accompanied by itching and burning, strawberry cervix (punctate hemorrhages on ectocervix)
Trichomonas vaginalis
Trichomonas vaginalis: Treatment
single oral dose of 2g (4 x 500mg tabs) of Metronidazole
Blood and tissue sporozoa, non-motile, asexual life cycle consists of shizogony & gametogony, sexual life cycle involves sporogeny, complex life cycle
Plasmodium
Most important parasitic disease in man
Plasmodium
Plasmodium: Transmission
bite of infected female mosquito (Anopheles filariasis minimus)
Plasmodium Life Cycle: Shizogony, Gemetogony
asexual
Plasmodium Life Cycle: Sporogony
sexual
Plasmodium: Asexual Host
man, intermediate
Plasmodium: Sexual Host
mosquito, definitive
Plasmodium: Infective Stage
sporozoites
Plasmodium: Diagnostic Stage
trophozoites (ring forms)
Pathologic findings from the destruction of RBCs, release of merozoites and splenic sequestration of infected cells, people with RBC defects (G6PD, sickle cell) are immune, partial immunity (premonition) seen in individuals who completely recover initial infection
Malaria (Plasmodium)
Plasmodium: 48 hour asexual cycle, malignant tertian, all aged RBCs, highest parasitemia, 0 merozoites, banana-shapes gametocytes, cerebral malaria, recrudescence, drug resistance
P. falciparum
Plasmodium: 48 hour asexual cycle, benign tertian, young RBCs, low parasitemia, 12-24 merozoites, large round gametocytes, relapse
P. vivax
Plasmodium: 72 hour asexual cycle, benign quartan, old RBCs, lowest parasitemia, 6-12 merozoites, compact gametocytes, recrudescence
P. malariae
Plasmodium: 48 hour asexual cycle, benign tertian, young RBCs, low parasitemia, 8 merozoites, small round gametocytes, relapse
P. ovale
Plasmodium: Recurrence of symptoms after a temporary abatement (2-4 weeks), seen in P. falciparum and P. malariae
Recrudescence
Plasmodium: Return of disease after its apparent cessation (1-6 months) due to reactivation of hypnozoites, seen in P. ovale and P. vivax
Relapse
Plasmodium: Diagnosis
thin & thick smears on Giemsa (thick - presence of organism, thin - species), higest yield when blood samples are taken during fever or 2-3 hours after peak
Malarial Dots: Punctate granulations present in RBCs invaded by P. ovale and P. vivax
Schuffner Dots
Malarial Dots: Coarse granulations present in RBCs invaded by P. falciparum, comma-shaped
Maurer Dots
Malarial Dots: Fine dots present in RBCs invaded by P. malariae
Ziemann Dots
Paroxysmal fever with malaise and bone pains, hemolytic anemia, jaundice, splenomegaly, parasitic pneumonitis, acute renal failure (blackwater fever), septic shock
Malaria (Plasmodium)
Plasmodium Findings: Malarial or Dürck’s granulomas
Cerebral Malaria
Plasmodium Findings: Acute renal failure, severe complication of P. falciparum, intravascular hemolysis, massive hemoglobinuria, acute renal failure, rare and sometimes fatal complication of quinine-sensitized persons
Blackwater Fever
Plasmodium Findings: Septic Shock
Algid Malaria
Plasmodium: High Endemicity
Palawan, Kalinga-Apayao, Ifugao, Agusan del Sur
Plasmodium: Chloroquine Resistance
Palawan, Davao del Norte, Compostela Valley
Plasmodium Treatment: Tissue Schizonticides
Primaquine - kill schizonts in the liver
Plasmodium Treatment: Blood Schizonticides
Chloroquine, Quinine - kill parasitic forms only in the erythrocyte
Plasmodium Treatment: Gametocides
Primaquine - kills gametocytes in blood
Plasmodium Treatment: Sporontocides
Proguanil, Pyrimethamine - prevent sporogony and multiplication in the mosquito
Plasmodium Treatment: Chloroquine-sensitive P. falciparum, P. malaria
Chloroquine
Plasmodium Treatment: P. vivax, P. ovale
Chloroquine + Primaquine
Plasmodium Treatment: Uncomplicated infections with Chloroquine-resistant P. falciparum
Quinine + Doxycycline/Clindamycin
Plasmodium Treatment: Severe or complicated infections with P. falciparum
Artesunate + Doxycycline/Clindamycin or Mefloquine/Malarone OR Quinidine gluconate
Plasmodium Treatment: Chloroquine-resistance
Mefloquine + Doxycycline
Plasmodium Treatment: Eradication of Hypnozoites
Primaquine
Plasmodium Treatment: Severe Cases/Pregnant
Quinidine, Quinine
Plasmodium Prophylaxis: Without resistant P. falciparum
Chloroquine
Plasmodium Prophylaxis: Chloroquine-resistant P. falciparum
Malarone, Mefloquine
Plasmodium Prophylaxis: Multidrug-resistant P. falciparum
Doxycycline
Plasmodium Prophylaxis: Terminal prophylaxis of P. vivax and P. ovale infection, alternative for primary prevention
Primaquine
Plasmodium Prophylaxis: Chloroquine-Sensitive Areas
Chloroquine 500mg/tab, 1 tab weekly
Plasmodium Prophylaxis: Chloroquine-Resistant Areas
Mefloquine 250mg/tab, 1 tab weekly, Malarone (Atovaquone 250mg/Proguanil 100mg)/ tab, 1 tab daily
Plasmodium Prophylaxis: Multidrug-Resistant Areas
Doxycycline 100mg/tab, 1 tab daily
Plasmodium: Prevention
chemoprophylaxis, insecticide-treated nets, insect repellant with DEET, biologic modification (cultivation of snails that eat mosquito larvae)
Tissue protozoan, definitive host - domestic cat, intermediate hosts - humans & other mammals, complex life cycle
Toxoplasma gondii
Toxoplasma gondii: Transmission
ingestion of cysts in raw meat and contaminated food, transplacentally
Toxoplasma gondii: Infective Stage
fecal oocysts
Toxoplasma gondii: Diagnostic Stage
trophozoites (bradyzoites)
Toxoplasma gondii Trophozoites: Rapidly multiplying, CMI limits spread
tachyzoites
Toxoplasma gondii Trophozoites: Slowly multiplying, important in tissue diagnosis
bradyzoites
Toxoplasma gondii: Diagnostic Test
IgM antibody
Toxoplasma gondii Disease: Heterophil-negative mononucleosis
immunocompetent
Toxoplasma gondii Disease: Encephalitis, ring-enhancing lesions
immunocompromised
Abortion, stillbirth, neonatal disease with hydrocephalus, encephalitis, chorioretinitis, hepatosplenomegaly, intracranial calcifications
Congenital Toxoplasma gondii Disease
Toxoplasma gondii: Treatment
Sulfadiazine + Pyrimethamine
Blood and tissue protozoan, 4 forms (amastigote, promastigote, epimastigote, trypomastigote), complex life cycle
Trypanosoma cruzi
Trypanosoma cruzi: Transmission
reduviid bug (Triatoma)
Trypanosoma cruzi: Infective Stage
metacyclic trypomastigotes
Trypanosoma cruzi: Diagnostic Stage
trypomastigotes in blood
Myocardial, glial, reticuloendothelial cells are frequent sites, cardiac muscle is the most frequently and severely affected tissue
Trypanosoma cruzi
Trypanosoma cruzi: Diagnosis
stained BMA or muscle biopsy, culture in special medium, xenodiagnosis - allowing an uninfected, laboratory-raised reduviid bug to feed on patient
Trypanosoma cruzi: Unilateral periorbital edema (Romaña’s sign), nodule near bite (chagoma), fever, LAD, hepatosplenomegaly
Acute Chagas’ Disease
Trypanosoma cruzi: Myocarditis, megacolon, megaesophagus (achalasia)
Chronic Chagas’ Disease
Trypanosoma cruzi: Treatment
Nifurtimox
Blood and tissue protozoan, 2 forms (epimastigote, trypomastigote), complex life cycle, remarkable antigenic variation
Trypanosoma brucei
Trypanosoma brucei: Types
gambiense, rhodesiense
Trypanosoma brucei: Transmission
tsetse fly (Glossina)
Trypanosoma brucei: Infective Stage
metacyclic trypomastigotes
Trypanosoma brucei: Diagnostic Stage
trypomastigotes in blood
Spread from the skin through the blood to the lymph nodes and the brain, somnolence (sleeping sickness) progresses to coma due to demyelinating encephalitis (ARAS, brainstem), cyclical fever spike (every 2 weeks) due to antigenic variation
Trypanosoma brucei
Trypanosoma brucei rhodesiense is _____ rapid and fatal than Trypanosoma brucei gambiense.
rhodesian is more rapid and fatal
Trypanosoma brucei: West
gambiense
Trypanosoma brucei: East
rhodesiense
Indurated skin ulcer (trypanosomal chancre), intermittent weekly fever and LAD, enlargement of the posterior cervical LN (Winterbottom’s sign), excessive somnolence, hyperesthesia (Kerandel’s sign), encephalitis, plasma cells with cytoplasmic Ig globules (Mott cells)
Trypanosoma brucei
Trypanosoma brucei Treatment: Blood-Borne
Suramin
Trypanosoma brucei Treatment: CNS Penetration
Melarsoprol
Trypanosoma brucei Treatment: West African, early
Pentamidine
Trypanosoma brucei Treatment: West African, CNS
Eflornithine
Trypanosoma brucei Treatment: East African, early
Suramin
Trypanosoma brucei Treatment: East African, CNS
Melarsoprol
Flagellated marine protists, algal blooms cause red tide
Dinoflagellates
Most common cause of red tide in the Philippines
Pyrodinium bahamense var. compressum
Most common cause of red tide in the US
Alexandrium
Dinoflagellates: Transmission
eating bivalve mollusks, fish obtained from red tide
Red Tide Season
May-August
Filter feeders accumulate toxins produced by
dinoflagellates
Shellfish Poisoning Syndromes: Saxitoxin
Paralytic
Shellfish Poisoning Syndromes: 15 min incubation period, facial paresthesia, total paralysis, respiratory failure
Paralytic
Shellfish Poisoning Syndromes: Brevetoxin
Neurotoxic
Shellfish Poisoning Syndromes: 15 min incubation period, facial paresthesis, slurred speech, ataxia, diarrhea, stroke-like symptoms
Neurotoxic
Shellfish Poisoning Syndromes: Okadaic Acid
Diarrheic
Shellfish Poisoning Syndromes: 30 min incubation period, diarrhea, nausea, vomiting, abdominal pain
Diarrheic
Shellfish Poisoning Syndromes: Domoic Acid
Amnesic
Shellfish Poisoning Syndromes: 30 min incubation period, diarrhea, short-term memory loss, seizures
Amnesic
Dinoflagellates: Treatment
gastric lavage with activated charcoal, supportive fluid resuscitation, endotracheal intubation for respiratory failure, Neostigmine and Edrophonium for muscle weakness
Free-living ameba, infected contact lenses, granulomatous amebic encephalitis
Acanthamoeba castellani
Free-living ameba, swimming in contaminated pools, primary amebic meningoencehalitis
Naegleria fowleri
Only ciliated protozoan to cause human disease
Balantidium coli
Round-based, wide-necked intestinal ulcers, dysentery, pigs
Balantidium coli
Ixodes tick, intraerythrocytic ring-shaped trophozoites in tetrads in the form of a Maltese cross
Babesia microti
Phlebotomus sandfly, infective promastigotes
Leishmania
Leishmania: Cutaneous
Leishmania tropica
Leishmania: Visceral / Kala-azar
Leishmania donovani
Leishmania: Mucocutaneous
Leishmania brasiliensis
Leishmania: Treatment
Sodium stibogluconate (Antimony compound)
Coccidial sporozoa, diarrhea in immunocompromised patients
Cyclospora cayetanensis, Isospora belli
Cestodes: Eggs/larvae in undercooked pork, pigs, in intestines
T. solium
Cestodes: Larvae in undercooked beef, cattle, in intestines
T. saginata
Cestodes: Larvae in undercooked fish, in intestines
D. latum
Cestodes: Eggs in food contaminated by dog feces, sheep, in liver
E. granulosus
Intestinal cestodes, differentiated based on scolex and gravid proglottids
Taenia
Taenia: 4 suckers, rostellum, 5-10 primary uterine branches in gravid proglottids, pork
T. solium
Taenia: 4 suckers, 15-25 primary uterine branches in gravid proglottids, beef
T. saginata
Taenia: Transmission
undercooked pork/beef
Taenia: Infective Stage
cysticerci, eggs (T.solium)
Taenia: Diagnostic Stage
gravid proglottids
Minor intestinal damage from adult tapeworms, cystecerci can become SOLs in the brain, living cystecerci do not cause inflammation
Taenia
Taenia: Abdominal pain, weight loss, pruritus ani, intestinal obstruction
T. saginata
Taenia: Mild intestinal symptoms, small infective eggs cross the BBB causing seizures (neurocysticercosis), worms in vitreous humor
T. solium
Taenia: Treatment
Praziquantel
Has 2 elongated sucking grooves for attachment, operculated eggs
Diphyllobothrium latum
Diphyllobothrium latum: Intermediate Hosts
fish, copepods
Diphyllobothrium latum: Transmission
undercooked fish
Diphyllobothrium latum: Infective Stage
plerocercoid larvae (fish muscle)
Diphyllobothrium latum: Diagnostic Stage
unembryonated egg
Abdominal pain, diarrhea, megaloblastic anemia due to vitamin B12 deficiency
Diphyllobothrium latum
Diphyllobothrium latum: Treatment
Praziquantel
Composed of scolex and only 3 proglottids, one of the smallest tapeworms
Echinococcus granulosus
Echinococcus granulosus: Intermediate Hosts
sheep, humans
Echinococcus granulosus: Definitive Host
dog
Echinococcus granulosus: Transmission
ingestion of eggs
Echinococcus granulosus: Infective Stage
embryonated eggs
Echinococcus granulosus: Diagnostic Stage
hydatid cysts
Cysts act as SOLs, if cyst ruptures, life-threatening anaphylaxis can occur
Echinococcus granulosus
Echinococcus granulosus: Cysts
hydatid cysts (liver), pulmonary cysts, cerebral cysts
Echinococcus granulosus: Treatment
surgical resection, Albendazole, PAIR procedure (Puncture, Aspiration, Injection, Reaspiration) - uses 95% Ethanol (helminthicidal, scolicidal)
Echinococcus multilocularis: Definitive Host
fox
Echinococcus multilocularis: Intermediate Host
rodents
Multiloculated cysts (honeycomb vesicles)
Echinococcus multilocularis
Dwarf tapeworm, most common tapeworm in developed countries, eggs are directly infectious, polar filaments, six-hooked larvae
Hymenolepsis nana
Rat tapeworm, accidental parasite
Hymenolepsis diminuta
Hymenolepsis diminuta: Transmission
ingestion of insects harboring eggs
Most common tapeworm of dogs and cats, barrel-shaped proglottids
Dipylidium caninum
Trematodes: Penetrate skin, in liver, snails
S. japonicum
Trematodes: Ingested with raw crab, in lungs, snails
P. westermani
Trematodes: Ingested with raw fish, in liver, snails
C. sinensis
Oriental blood fluke, adults exist as separate sexes, reside in mesenteric and portal veins
Schistosoma japonicum
Schistosoma japonicum: Intermediate Host
snail (Oncomelania hupensis quadrasi)
Schistosoma japonicum: Transmission
cercariae penetrate skin
Schistosoma japonicum: Infective Stage
cercariae
Schistosoma japonicum: Diagnostic Stage
eggs in feces
Schistosoma haematobium: Diagnostic Stage
eggs in urine
Schistosoma japonicum: Diagnosis
Kato-Katz technique, Circumoval Precipitin Test (COPT) - ovoid egg with small hook
Presence of eggs cause granuloma formation, liver granulomas lead to pre-sinusoidal obstruction, hepatomegaly and portal hypertension, evade host defenses by coating themselves with host antigens
Schistosoma japonicum
Itching and dermatitis (swimmer’s itch), systemic hypersensitivity resembling serum sickness (Katayama fever)
Acute Schistosoma japonicum Infection
Chronic liver disease, portal hypertension, colonic, pulmonary and cerebral involvement, Jacksonian/focal seizures
Chronic Schistosoma japonicum Infection
Schistosoma japonicum: Endemic Areas
Sorsogon, Samar, Leyte, Oriental Mindoro, Bohol, all of Mindanao except Misamis Oriental
Schistosoma japonicum: Treatment
Praziquantel
Lung fluke, hermaphrodite
Paragonimus westermanii
Paragonimus westermanii: Intermediate Hosts
snail (Antemelania asperata), mountain crab (Sundathelphusa philippina)
Paragonimus westermanii: Transmission
undercooked/raw fish
Paragonimus westermanii: Infective Stage
metacercariae
Paragonimus westermanii: Diagnostic Stage
unembryonated egg
Paragonimus westermanii: Diagnosis
3% NaOH preparation
Paragonimus westermanii: Eggs
ovoid, thin opercular end, thick abopercular end
Develops a fibrous wall that provokes a granulomatous reaction, secondary bacterial infection frequently occurs
Paragonimus westermanii
Chronic cough with bloody sputum, endemic hemoptysis, ring-shadow opacity on CXR, closely resembles TB
Paragonimiasis
Paragonimus westermanii: Treatment
Praziquantel
Asian liver flukes, hermaphrodite, inflammatory response can cause hyperplasia and fibrosis of biliary tract
Clornichis sinensis
Asian Liver Flukes
Clornichis sinensis, Opistorchis viverrini
Clornichis sinensis: Intermediate Hosts
snail (Parafossarulus), fish (Cyprinidae)
Clornichis sinensis: Transmission
uncooked/raw fish
Clornichis sinensis: Infective Stage
metacercariae
Clornichis sinensis: Diagnostic Stage
embryonated eggs
Clornichis sinensis: Diagnosis
direct fecal smear, potassium permanganate stain (melon-like ridges)
Fever, eosinophilia, LAD, tender hepatomegaly, embryonated eggs in direct fecal smear
Acute Clornichis sinensis Infection
Hepatobiliary disease, pancreatitis, cholangiocarcinoma (Klatskin tumor), neurocirculatory dystonia
Clornichis sinensis
Clornichis sinensis: Treatment
Praziquantel
Sheep liver fluke, watercress (aquatic plants), obstructive jaundice and painful pharyngitis (Halzoun)
Fasciola hepatica
Intestinal fluke, aquatic vegetation, gland abscesses, anasarca and coma from accumulation of toxins (worm intoxication)
Fasciolopsis buski
Intestinal fluke, raw fish containing cysts, mimics peptic ulcer disease
Heterophyes heterophyes
Nematodes: Intestines, ascariasis, ingestion of eggs
Ascaris
Nematodes: Intestines, hookworm, larval penetration of skin
Ancylostoma, Necator
Nematodes: Intestines, whipworm, ingestion of eggs
Trichuris
Nematodes: Intestines, pinworm, ingestion of eggs
Enterobius
Nematodes: Intestines, strongyloidiasis, larval penetration of skin
Strongyloides
Nematodes: Intestines, capillariasis, eggs in undercooked fish
Capillaria
Nematodes: Tissue, filariasis, mosquito bite
Wuchereria, Brugia
Nematodes: Tissue, trichinosis, larvae in uncooked meat
Trichinella
Most common and largest nematode, giant roundworm, soil-transmitted helminth
Ascaris lumbricoides
Ascaris lumbricoides: Transmission
ingestion of eggs
Ascaris lumbricoides: Infective Stage
embryonated eggs
Asian liver flukes, hermaphtodite, inflammatory response can cause hyperplasia and fibrosis of biliary tract
Clornichis sinensis
Ascaris lumbricoides: Diagnosis
direct fecal smear, Kato-Katz technique
Clornichis sinensis: Intermediate Hosts
snail (Parafossarulus), fish (Cyprinidae)
Clornichis sinensis: Transmission
uncooked/raw fish
Clornichis sinensis: Infective Stage
metacercariae
Clornichis sinensis: Diagnostic Stage
embryonated eggs
Clornichis sinensis: Diagnosis
direct fecal smear, potassium permanganate stain (melon-like ridges)
Fever, eosinophilia, LAD, tender hepatomegaly, embryonated eggs in direct fecal smear
Acute Clornichis sinensis Infection
Hepatobiliary disease, pancreatitis, cholangiocarcinoma (Klatskin tumor), neurocirculatory dystonia
Clornichis sinensis
Clornichis sinensis: Treatment
Praziquantel
Necator & Ancylostoma: Diagnosis
direct fecal smear, Kato-Katz technique
Intestinal fluke, aquatic vegetation, gland abscesses, anasarca and coma from accumulation of toxins (worm intoxication)
Fasciolopsis buski
Intestinal fluke, raw fish containing cysts, mimics peptic ulcer disease
Heterophyes heterophyes
Nematodes: Intestines, ascariasis, ingestion of eggs
Ascaris
Nematodes: Intestines, hookworm, larval penetration of skin
Ancylostoma, Necator
Nematodes: Intestines, whipworm, ingestion of eggs
Trichuris
Nematodes: Intestines, pinworm, ingestion of eggs
Enterobius
Trichuris trichiuria: Infective Stage
embryonated eggs
Nematodes: Intestines, capillariasis, eggs in undercooked fish
Capillaria
Nematodes: Tissue, filariasis, mosquito bite
Wuchereria, Brugia
Nematodes: Tissue, trichinosis, larvae in uncooked meat
Trichinella
Most common and largest nematode, giant roundworm, soil-transmitted helminth
Ascaris lumbricoides
Ascaris lumbricoides: Transmission
ingestion of eggs
Ascaris lumbricoides: Infective Stage
embryonated eggs
Ascaris lumbricoides: Diagnostic Stage
fertilized egg (unembryonated)
Ascaris lumbricoides: Diagnosis
direct fecal smear, Kato-Katz technique
Major damage occurs during larval migration, principal site of tissue reaction is in the lungs where inflammation with an eosinophilic exudate occurs, heavy worm burden may contribute to malnutrition
Ascaris lumbricoides
Ascaris lumbricoides: Diseases
hypersensitivity pneumonitis (Loeffler’s Syndrome), acute intestinal obstruction, hepatobiliary ascariasis, pancreatitis, malabsorption syndromes, nutrient deficiencies
Ascaris lumbricoides: Treatment
Albendazole (greater larvicidal activity than Mebendazole)
Parasites with Transpulmonary Phase
Ascaris, Necator, Ancylostoma, Strongyloides
Soil-transmitted helminth, blood-sucking nematodes, hookworms, differentiated based on the character of buccal spears of filariform larvae
Necator americanus, Ancylostoma duodenale
Necator & Ancylostoma: Transmission
larvae penetrate skin
Necator & Ancylostoma: Infective Stage
filariform larvae
Necator & Ancylostoma: Diagnostic Stage
eggs in feces
Necator & Ancylostoma: Diagnosis
direct fecal smear, Kato-Katz technique
Major damage due to blood loss (0.25mL blood/worm/day) at site of attachment, blood consumed oozes in response to an anticoagulant made by the worm, microcytic anemia caused by blood loss
Necator americanus, Ancylostoma duodenale
Ground itch at site of entry, serpiginous tracks (cutaneous larva migrans), eosinophilic pneumonia during transpulmonary stage, mild GIT syndromes
Acute Necator/Ancylostoma Infection
Microcytic anemia from blood-sucking nematodes, hypoalbuminemia
Chronic Necator/Ancylostoma Infection
Necator & Ancylostoma: Treatment
Albendazole
Whipworm, soil-transmitted helminth
Trichuris trichiuria
Strongyloides stercoralis: Treatment
Ivermectin
Trichuris trichiuria: Diagnostic Stage
unembryonated eggs
Trichuris trichiuria: Diagnosis
direct fecal smear, Kato-Katz technique
Trichuris trichiuria: Eggs
barrel-shaped eggs with bipolar plugs (Chinese lantern)
Burrow their hair-like anterior ends into the intestinal mucosa, do not cause significant anemia
Trichuris trichiuria
Diarrhea, rectal prolapse from increased peristalsis to expel the worms
Trichuris trichiuria
Trichuris trichiuria: Treatment
Mebendazole
Pinworm, seatworm, soil-transmitted helminth, life cycle is confined to humans, most common sexually transmitted helminths in developed countries (cosmopolitan worm)
Enterobius vermicularis
Enterobius vermicularis: Transmission
ingestion/inhalation of eggs
Enterobius vermicularis: Infective Stage
embryonated eggs
Capillaria philippinensis: Treatment
Albendazole
Enterobius vermicularis: Diagnosis
Graham’s scotch tape technique (D-shaped eggs)
Female releases thousands of fertilized eggs on perianal skin, eggs develop into larvae causing perianal pruritus, autoinfection can occur
Enterobius vermicularis
Pruritus ani, eosinophilic enterocolitis, vulvovaginitis, appendicitis (oxyuriasis)
Enterobius vermicularis
Enterobius vermicularis: Treatment
Pyrantel pamoate
Soil-transmitted helminth, facultative parasites
Strongyloides stercoralis
Strongyloides stercoralis: Transmission
larvae penetrate skin
Strongyloides stercoralis: Infective Stage
filariform larvae
Strongyloides stercoralis: Diagnostic Stage
rhabditiform larvae
Strongyloides stercoralis: Diagnosis
Harada-Mori culture
Larvae penetrate intestinal wall directly without leaving host and migrate to the lungs (autoinfection), hyperinfection in immunocompromised patients
Strongyloides stercoralis
Ground itch at site of entry, eosinophilic pneumonia, mild watery diarrhea, facultative parasite
Acute Strongyloides stercoralis Infection
Serpiginous track (larva currens), duodenitis, paradoxical asthma, hyperinfection syndrome
Chronic Strongyloides stercoralis Infection
Strongyloides stercoralis: Treatment
Ivermectin
Intestinal nematode, pudoc worm, only nematode whose life cycle involves a migratory bird
Capillaria philippinensis
Wuchereria & Brugia: Treatment
Diethylcarbamazine (DEC)
Capillaria philippinensis: Infective Stage
infective larvae
Capillaria philippinensis: Diagnostic Stage
unembryonated eggs
Capillaria philippinensis: Diagnosis
direct fecal smear, Kato-Katz technique
Capillaria philippinensis: Eggs
peanut-shaped eggs with flattened bipolar plugs
Embryonated eggs can cause autoinfection and hyperinfection, leads to ulcerative and compressive degeneration of enterocytes resulting in severe malabsorption
Capillaria philippinensis
Borborygmus, fever, abdominal pain, eosinophilia
Acute Capillaria philippinensis Infection
Chronic watery diarrhea, edema, wasting, protein-losing enteropathy, anasarca, hypogammaglobulinemia
Chronic Capillaria philippinensis Infection
Capillaria philippinensis: Treatment
Albendazole
Blood and tissue nematode, most debilitating nematode infection, farmer from abaca plantation
Wuchereria bancrofti, Brugia malayi
Filariasis: Smoothly curved, widespread prevalance, scrotal lymphatics, hydrocoele, more severe
Wuchereria bancrofti
Filariasis: Kinky, terminal nuclei, SEA prevalence only, limb lymphatics, elephantiasis, less severe
Brugia malayi
Wuchereria bancrofti: Vectors
Culex, Aedes, Anopheles
Brugia malayi: Vector
Mansonia
Wuchereria & Brugia: Transmission
mosquito bite
Wuchereria & Brugia: Infective Stage
3rd stage larvae
Wuchereria & Brugia: Diagnostic Stage
microfilariae
Wuchereria & Brugia: Diagnosis
thick blood smear (curved or kinky microfilariae), specimen collection best done at night (8pm-4am) - nocturnal periodicity, diethylcarbamazine (DEC) provocation test
Adult worms in lymph nodes cause inflammation that obstructs lymphatic vessels causing lymphedema, microfilariae do not cause symptoms
Wuchereria & Brugia
Acute adenolymphangitis, filarial fever, nocturnal wheezing (tropical pulmonary eosinophilia), small epithelioid granulomas (Meyers-Kouvenaar bodies), expatriate syndrome
Acute Wuchereria/Brugia Infection
Hydrocoele, elephantiasis, milky urine (chyluria)
Chronic Wuchereria/Brugia Infection
Bancroftian Filariasis: Endemic Areas
Sorsogon, Samar, Leyte, Palawan, Camarines, Albay, Mindoro, Marinduque, Romblon, all of Mindanao
Malayan Filariasis: Endemic Areas
Eastern Samar, Agusan del Sur, Palawan, Sulu
Wuchereria & Brugia: Treatment
Diethylcarbamazine (DEC)
Tissue nematode from pigs
Trichinella spiralis
Trichinella spiralis: Intermediate Host
pigs
Trichinella spiralis: Transmission
undercooked pork
Trichinella spiralis: Infective Stage
encysted larvae
Trichinella spiralis: Diagnostic Stage
encysted larvae
Trichinella spiralis: Diagnosis
muscle biopsy, larvae within striated muscle, elevated CPKs, xenodiagnosis
Trichinella spiralis Stage: Liberated from pork by gastric juices
Intestinal Stage
Trichinella spiralis Stage: Disseminate hematogenously to streaked skeletal muscle, encysted within a host-derived cell (nurse cell)
Muscle Stage
Fever, muscle, pain, periorbital edema, eosinophilia, hemorrhagic phenomena (subconjunctival, splinter)
Mild Trichinella spiralis Infection
Myocarditis, encephalitis, pneumonia, respiratory myositis
Severe Trichinella spiralis Infection
Trichinella spiralis: Treatment
Thiabendazole
Transmitted by the female blackfly (Simulium), dermal nodules, hanging groin, lizard skin, river blindness, lysis of worm leads to Mazzotti reaction
Onchocerca volvulus
Onchocerca volvulus: Treatment
Ivermectin (Mazzotti Reaction)
Transmitted by the deer fly or mango fly (Chrysops), subcutaneous edema (Calabar swellings), worm crawling across conjunctiva
Loa loa
Guinea fire worm, serpents of Israelites, transmitted when copepods are swallowed in water, pruritic painful papule, live worm in skin ulcer
Dracunculus medinensis
Dracunculus medinensis: Treatment
mechanical removal daily
Dog ascaris, visceral larva migrans, ocular toxocariasis, ocular larva migrans, uveitis, endophthalmitis
Toxocara canis
Transmitted in undercooked seafood, eosinophilic meningitis, most common cause of parasitic meningitis
Ancylostoma caninum / brasiliense
Zoonotic roundworms, ingested in raw seafood, eosinophilic gastroenteritis
Anisakis simplex
Arthropods: Pruritus of scalp, trunk, nits on hair shaft
Pediculus humanus (lice)
Arthropods: Pruritus in pubic area, nits on hair shaft
Phthirus pubis (lice)
Arthropods: Pruritic, painful and erythematous nodule, larva may be seen emerging from nodule
Dermatobia hominis (flies)
Arthropods: Pruritic, erythematous wheal
Cimex lectularius (bedbugs)
Arthropods: Pruritic, erythematous papules, linear tracks
Sarcoptes scabei (mites)
Arthropods: Ascending paralysis
Dermacentor (ticks)
