Parasitology Week 1

Intro Lab 1 Sporozoea Protozoa

Parasitism

Relationship between a host and the organism in which the organism benefits at the expense of the host

Parasitemia

Parasites in the blood

Carrier

Host harboring a parasite but exhibiting no symptoms

Symbiosis

Association of two different species of organisms exhibiting metabolic dependence by their relationship

Commensalism

Association of two different species or organisms where one is benefitted and the other is neither benefited nor injured

Accidental host

Infection of a host other than the normal host species. Parasite may not reach full development

Definitive host

The animal in which the parasite passes its adult existence, sexual reproductive phase, or both

Intermediate host

Animal in which the parasite passes its larval stage or asexual reproduction phase

Reservoir host

Animal that harbors a species of parasite that is also parasitic for humans and can infect

What percentage of the worlds population suffer consequences of parasitic infections ?

24%

environments that lead to parasitic infections

Poverty, poor sanitation, contaminated food and water, poor health education, tropical climates, travel

Helminth classes

Nematoda (nematodes “round worms”)

Cestoda (cestodes “tape worms”)

Digenea ( trematodes “flat worms and flukes”)

Classes in Protozoa

Lobosea (pseudopodia ameba)

Zoomastigophorea (flagella)

Ciliophora (cilia)

Sporozoea (sexual and asexual reproduction)

Sporozoa general characteristics

Lack locomotion

Life cycle alternates between sexual and asexual

Definitive host life cycle stage

Sexual reproduction

Intermediate hosts life cycle stage

Asexual reproduction

Sporogony

Sexual reproduction of spores and sporozoites

Schizogony (human host)

Asexual multiplication

Paroxysm

Toxic materials released from ruptured RBC

Plasmodium epidemiology

Malaria (most common protozoal disease)

Transmitted by Anopheles mosquito

Can cross placenta

Malaria symptoms

Splenomegaly, chills, fever, sweats, anorexia, joint pain, leukopenia, normocytic anemia, hemolytic anemia

Malaria diagnosis

ID of species specific ring forms, gametes, and schizonts (in blood cells) on blood stains

Plasmodium falciparum disease

Malignant malaria

Plasmodium falciparum symptoms

36-48 hour paroxysms, infect RBC, hemolytic anemia (black water fever)

Plasmodium falciparum diagnosis

Trophs (ring forms) and crescent gametocytes in RBCs

Maurer’s clefts or red dots

Ring form Plasmodium falciparum

Gametocyte of Plasmodium falciparum

Plasmodium malariae disease

Quartan malaria

Quartan malaria symptoms

Paroxysms every 72 hours

Quartan malaria symptoms

Trophozoite band forms and schizonts (6-12 merozoites in a rosette)

Band form of Plasmodium malariae

Schizont of Plasmodium malariae

Plasmodium vivax disease

Tertian malaria

Tertian malaria symptoms

Paroxysms every 48 hours

Tertian malaria diagnosis

Ring forms infecting young RBCs, schuffners dots, and schizonts w 12-24 merozoites

Plasmodium ovale disease

Ovale malaria

Ovale malaria diagnosis

Ring forms, oval RBCs, schuffners dots, schizonts 8-12 merozoites

Babesia characteristic ring form

Maltese cross formation

Toxoplasma gondii transmission

Oocytes shed in cat feces and aerosolized

Toxoplasmosis symptoms in adults

Asymptomatic or mimic mononucleosis (headache, fever, malaise, myalgia, lymphadenopathy)

Toxoplasmosis symptoms in children

Rash myocarditis, encephalomyelitis, hepatitis, retinochoroiditis (blindness)

Toxoplasma gondii diagnosis

Encrusted tachyziotes in biopsy materials

Serology

PCR

Cryptosporidium parvum and hominis transmission

Common infection for cattle, rodents, and fowl

Fecal-oral

Not killed by chlorine

Cryptosporidium parvum and hominis symptoms

Abdominal pain and diarrhea

Cryptosporidium diagnosis

Acid fast oocytes in feces, ID in biopsies, PCR, serology

Cryptosporidium parvum oocytes

Cystoisospora belli infection/symptoms

Indistinguishable from C. parvum

Low fever, headache, diarrhea, colicky and abdominal pain

Cystoisospora belli diagnosis

Elliptical/oval oocyst 20-33um long and 10-19um wide

Cystoisospora belli oocysts

Cyclospora cayetanensis transmission

Contaminated food or water (humans are the only hosts)

Cyclospora cayetanensis symptoms

Diarrhea alternating w constipation, anorexia/weightloss, cramping, vomiting, nausea, low fever

Enterocytozoon bieneusi infections

Intestinal and hepatobiliary

Encephalitozoon hellem infections

Ocular

Encephalitozoon intestinalis infections

Intestinal and disseminated

Microsporidia (encephalo/entero) diagnosis

Small intestinal biopsy

1-3um spores (deep red dot)

PCR

Microsporidia spore

Amoebae

Single celled eukaryotes that feed by engulfing and move by pseudopodia

Trophozoite form

Motile reproductive and feeding stage

Cyst form

Non motile resting stage that is resistant to the environment

Chromatoidal bodies

Dark staining cytoplasmic inclusion of chromatin

Endosome or karyosone

Mass of organelles or chromatin in the nucleus

Amoebae diagnosis

Motile throphozoites in fresh warm liquid stools via wet mount and iodine preps

Trophozoites / cysts in fixed smears w trichrome stain

Trophozoites/ cysts in other body tissues or fluids w serology

Differentiation of amoebas

Shape of nucleus, number of nuclei, size, shape, inclusions

Entamoeba histolytica disease

Amebiasis, transmission by ingestion, intestinal disease, dissemination

Trophozoite microscopic characteristics of E. histolytica

10-20um, irregular shape (teardrop), single nucleus w karyosome , ingested RBCs (only one)

Cyst microscopic characteristics of E.histolytica

10-20um, 1,2, or 4 nuclei w central karyosome, rounded chromatoidal bars

Entamoeba coli characteristics

Commensal, smaller than 10um, up to 8 nuclei w eccentric karyosome, pointed sharp chromatin bars

Blastocystis hominis disease symptoms

Recurrent diarrhea, abdominal cramping, anorexia, flatulence

B. hominis microscopic description

5-15 um

Empty central body with nuclear material on the outer layer

Naegleria fowleri disease

Entry through nasal mucosa, causes primary amebic meningoencephalitis, found in csf and tissues

Flagella

Provides locomotion

Axoneme

Intracellular portion of a flagellum

Axostyle

Rod that provides support in flagellates

Pathogenic intestinal flagellates

Giardia lamblia

Dientamoeba fragilis

Pathogenic vaginal flagellate

Trichomonas vaginalis

Blood and tissue flagellates

Trypanosoma sp

Leishmania

Giardia lamblia

Most common diarrheal disease transmitted by contaminated water

Only Protozoa that resides in the duodenum

Giardiasis

“Traveler diarrhea”, “beaver fever”, “backpackers diarrhea”

Mild-severe diarrhea

Trophozoites/cysts in stool and biopsies

Microscopic characteristics of Giardia lamblia

Trophozoite: bilateral symmetry, 2 nuclei, 8 flagella

Cyst: oval w 2-4 nuclei

Dientamoeba fragilis

Associated w diarrhea

No cysts, Trophozoite has 2 nuclei

Trichomonas vaginalis

Trophs live in vagina, urethra, epididymis and prostate

Trichomonas vaginalis diagnosis

Wet mount from urethral discharge, vaginal smear, or urine

“Jerky” motility

Trophozoite of E. histolytica

Cyst of E. histolytica

Entamoeba coli cyst

Blastocystis hominis

Trophozoite of Giardia lamblia

Giardia lamblia cysts

Dientamoeba fragilis Trophozoite

Trichomonas vaginalis trophozoite

Trichomonas cruzi trypomastigote

Leishmania donovani amastigote forms

Trypanosoma cruzi disease

Chagas: mild swelling (infected site) and fever

Leishmania donovani disease/symptoms

Spread from cutaneous lesion to internal organs

Ciliophora pathogenic species

Balantidum coli

Largest human intestinal protozoa

Balantidium coli

Symptoms of balantadium coli

Asymptomatic or diarrhea w alternating constipation

Blastintidium coli diagnosis

Trophozoites or cysts in feces

B.coli trophozoite