Medical Parasitology lab

Entamoebia

• Constantly change in shape

1. Intestinal

• Pathogenic E. histolytica

• No pathogenic (E. coli (>4 nuclei in the cyst)

2. Free living

• Feco-oral rout

E hostylitica

• Habitat

• Mucosa and submucosa of large intestine

• 3 stage

• Trophozoite

• Precyst : intermediate stage between Trophozoite and cyst

• Cyst

Trophozoite

• invasive form• Passed only of patient with active dysentery• Its size is 15-30 µm.• The cytoplasm has 2 zones

• a hyaline outer margin (ectoplasm) • a granular inner region that may contain red

blood cells ,food vacuoles (endoplasm). • Single nucleus, spherical contain central dot

(karysome)• It has pseudopodia: long finger like projection of

endoplasm through ectoplasm• Motile: active unidirectional progressive and

purposeful movement

Cyst

• Infective form found in formed stool• Cysts are present in the lumen of the

colon and in formed feces.• Subspherical cysts of pathogenic

amebas range from 10-20 µm. • Smaller cysts 10 -3.5µm are

considered nonpathogenic (E. hartmanni).

• Cysts may contain 1-4 nuclei, a glycogen vacuole and chromatoidalbodies with characteristic rounded ends.

• Covered with smooth chitinous wall

Flagellate

• Tissue flagellat:

• Giardia lamblia (Intestinal)

• Trichomonas vaginalis (STD)

• The hemoflagellates of humans

• Trypanosoma

• Leishmania

Giardiasis

• Highest in developing countries

• Highest in children

Trophozoite• heart-shaped, symmetric, 10-20 µm

in length, • 4 pairs of flagella,• 2 nuclei with prominent central

karyosomes, • A large concave sucking disk in the

anterior portion occupies much of the ventral surface.

• The swaying or dancing motion of trophozoites in fresh preparations is unmistakable.

Cysts • found in the stool-often in enormous

numbers. • As the parasites pass into the colon, they

typically encyst.• They are thick-walled, highly resistant,• 8-14 µm in length, • contain 2 nuclei as immature & 4 as mature

cysts.

Giardia lamblia

Trophozoites Cysts

Trichomoniasis

• Trophozoites of Trichomonas vaginalis

are

• Oval shape

• 7-30 µm long.

• They have five flagella: four anteriorly

directed flagella and one posteriorly

along the outer membrane of the

undulating membrane.

• The large nucleus is usually located at

the wider, anterior end and contains

many chromatin granules and a small

karyosome.

• It moves with wobbling and rotating

motion

T. Vaginalis trophozoite

• Oval shape typically measure 7-15um

• Fg=flagella

• Bb=basal body

• Nu=nucleus (single elongated nucleus)

• Ax=axostyle

• um=undulating membrane

• Cy=cytostomal groove

• Cs=costa

• Leishmaniasis is transmitted by the bite of female phlebotomine sandflies. The

sandflies inject the infective stage, promastigotes, during blood meals .

Promastigotes that reach the puncture wound are phagocytized by macrophages

and transform into amastigotes . Amastigotes multiply in infected cells and affect

different tissues, depending in part on the Leishmania species . This originates the

clinical manifestations of leishmaniasis. Sandflies become infected during blood

meals on an infected host when they ingest macrophages infected with

amastigotes. In the sandfly's midgut, the parasites differentiate into

promastigotes , which multiply and migrate to the proboscis .

AmastigotesPromastigotes:

a flagellum and a kinetoplast

(arrow) anterior to the nucleus.

They are the infective stage to

humans.

Promastigotes:

Note the multiplication by

longitudinal binary fission (arrow)

that occurs naturally in the gut of

sandfly vectors.

Helminthes

• Helminths are invertebrates characterized by elongated, flat or round bodies.

• Platyhelminthes (flat) (hermaphrodite)

• Trematodes (flukes)

• Cestodes (tapeworms )

• Nemathelminthes (circular)

• Nematodes (Roundworms)

Trematodes

• Flat

• Suckers

• Digestive system

• Genetal system (testes and uterus)

• Intermediate host : snail

Schistosomiasis (‘bilharziasis)

• Schistosomiasis (‘bilharziasis’) is an infection with parasitic blood flukes:

Schistosoma mansoni, S. haematobium, S. japonicum,

Cestodes

• Flat, segmented, tape worm

• Scolics

• Neck dividing

• Up to 10 meter

• No digestive system

• Gental system (male, female)

• Immature segment, mature segment, gravid segment

Echinococcus granulosus and Echinococcus

multilocularis

• Echinococcus granulosus and Echinococcus multiloculariscause echinococcosis (Hydatid disease), common in central and Eastern Europe

• Patients presenting with primary infection are often asymptomatic. Latent infections may present years later with symptoms caused by mass effect within organs, obstruction of blood or lymphatic flow, or complications such as rupture or secondary bacterial infections. Fever and acute hypersensitivity reactions, including anaphylaxis, may be the principal manifestations of cyst rupture.

Nematodes

• Female or male

• Cylindrical

• 4 tubes

• Digestive system, genital system, excretory system, nervous system.

Ascaris lumbricoides

Infect by eggs that are strongly resistant to desiccation &

environmental conditions.

• Eggs are 75x40 µm, with a thick mamillated brownish shell.

• Freshly passed eggs in feces are not infective, they require 2-3

weeks to develop to be embryonated (contain larva).

• Male

• 15-30cm * 2-4mm

• Posterior end curved to form hook

• Femal

• 20-40cm *3-6mm

• Posterior end straight

• Distinct groove is present at valvar opening

• 2,00,000 eggs per day

• 2 type of eggs

• Fertilized egg

• Embyronated unsegmented ovum

• Develop into the infective form

• Round oval

• Unfertilized

• Atrophied ovum

• Elliptial in shape

• larger

Unfertilized egg

Elongated

Thin shelled

Disorganized internal content

Ascaris lumbricoides

Unfertilized egg

Elongated

Thin shelled

Disorganized internal

content

Egg containing a larva-

infective if ingested

Adult worms

Trichuris trichiura• Whip-worm, adults 3-7cm, live in caecum & colon of man.

• Eggs are barrel-shaped, 50x25 µm with a thick brown shell and a

mucoid plug at each pole. They are passed in feces to complete

development in soil as in Ascaris. This emryonated egg is the infective

stage.

Adults of T. trichiura Egg of T. trichiura

Enterobius vermicularis (Pinworm)

Small nematode, a common parasite among children, it is unique in that

eggs are viable shortly after being laid directly on the perianal skin. They

can be accidentally ingested, or passed on fingers, clothing or fecal flecks

to others.

Itching around the anal or vaginal areas are the most common pinworm

symptoms. Suspect a pinworm infection if the child shows night time

itching in these areas.

Pinworm EggsAn adult pinworm An adult pinworm

trematodes Other name Site of

infection

presentation Infective stage Diagnostic

stage

treatment

Enterobiasis

(pinworm)

Enterobius

vermicularis

Small

intestine

Pruritus ani, white worms visible in the

stools or perianal region

ingesting the

organism’s eggs

eggs mebendazole

or pyrantel

pamoate

Ascariasis

(roundworm)

Ascaris

lumbricoides

Small

intestine

Larvae grow in the intestine, causing

abdominal symptoms, including

intestinal obstruction

ingestion of soil

containing the

organism’s eggs. Then

to the blood

eggs mebendazole

or pyrantel

pamoate

Trichuriasis

(whipworm)

Trichuris

trichiura

Small

intestine

asymptomatic; however, abdominal

pain, diarrhea, flatulence, and rectal

prolapse can occur

ingestion of soil

containing the

organism’s eggs, dirct

to small intestine

eggs mebendazole

Hookworm Ancylostoma

duodenale and

Necator

americanus

Small

intestine

causing anorexia; ulcer-like symptoms,

and

chronic intestinal blood loss, leading to

anemia.

direct skin

penetration by larvae

found in soil. Then to

the blood

eggs mebendazole

or pyrantel

pamoate

Strongyloidiasis

(threadworm)

Strongyloides

stercoralis

Small

intestine

fatal outcome in immunocompromised

patients because of dissemination to the

CNS or other deep organs

(hyperinfection syndrome)

direct skin

penetration by

filariform larvae

found in soil. Then to

the blood

Rhabditi-form

larvae in the

stool

thiabendazole,

albendazole or

ivermectin

Soil-transmited helminths: egg passed in feces( fertilized, poor sanitation)…infective stage (mature egg or larvae)Eggs: contaminated food, water , hands

trematodes Other name presentation Infective

stage

Diagnostic

stage

treatment

Onchocerciasis

(river

blindness)

Onchocerca

volvulus

subcutaneous nodules, pruritic skin rash,

and ocular lesions often causing blindness.

bite

of a female

blackfly.

detection of

microfilariae in

skin biopsy.

ivermectin

and/or surgery.

Filariasis

(elephantiasis)

Wuchereria

bancrofti and Brugia

malayi

worms block the flow of lymph, causing

edematous arms, legs, and scrotum

bite of

infected

female

Anopheles

and Culex

mosquitoes

detection of

microfilariae in

blood.

a combination

of

diethylcarbama

zine and

albendazole

Loiasis Loa loa The larvae crawl under the skin, leaving

characteristic tracks. They can enter the

eye where adult worms are visible in the

subconjuctival space around the iris.

deer flies detection of

microfilariae in

blood.

diethylcarbama

zine.

Trichinosis Trichinella spiralis eating

encysted

larvae in

undercooke

d pork.

locating coiled

encysted

larvae in a

muscle biopsy.

thiabendazole;