2. Protozoa
Are single celled animals
Trophozoites are motile
Cysts are involved in transmission
3. GENERALITIES:
Parasites are organisms that obtain food and
shelter by living on or within another organism.
The parasite derives all benefits from association
and the host may either not be harmed or may
suffer the consequences of this association, a
parasite disease.
The parasite is termed obligate when it can live
only in association with a host or it is classified
as facultative when it can live both in or on a
host as well as in a free form.
4. Parasites which live inside the body are
termed endoparasites whereas those
which exist on the body surface are called
ectoparasites.
Parasites that cause harm to the host are
pathogenic parasites while those that
benefit from the host without causing it
any harm are known as commensals
5. What needs to be known?
Organism name ( scientific & common)
Morphology (cyst, egg, larva, tophozoite,
adult – M & F )
Etiology
Epidemiology
Life Cycle
Symptoms, Pathology, Immunology
Diagnosis, Treatment & Prevention
6. INTESTINAL AND LUMINAL
PROTOZOA
Organism that harbors the parasite and suffers a
loss caused by the parasite is a host.
The host in which the parasite lives its adult and
sexual stage is the definitive host
The host in which a parasite lives as the larval
and asexual stage is the intermediate host.
Other hosts that harbor the parasite and thus
ensure continuity of the parasite's life cycle and
act as additional sources of human infection are
known as reservoir hosts.
An organism (usually an insect) that is
responsible for transmitting the parasitic
infection is known as the vector.
7. Intestinal and luminal protozoa
significant to human health include
Entamoeba histolytica (Amoebae)
Balantidium coli (Ciliates)
Giardia lamblia and Trichomonas vaginalis
(Flagellates)
Cryptosporidium parvum and Isospora
belli (Sporozoa)
8. Organism Transmission Symptoms Diagnosis Treatment
GI: Iodoquinol or
Dysentery with blood Stool: cysts with 1-4
Metronidazole
Entameba histolytica Oro-fecal and necrotic tissue. nuclei and/or trophs.
Abscess:
Chronic: abscesses Trophs in aspirate.
Metronidazole
Fowl-smelling, bulky Stool: typical old man
Iodoquinol or
Giardia lamblia Oro-fecal diarrhea; blood or giardia troph and/or
Metronidazole.
necrotic tissue rare. cyst.
Dysentery with blood
Oro-fecal; Stool: ciliated trophs Iodoquinol or
Balantidium coli and necrotic tissue
zoonotic but no abscesses.
and/or cysts. Metronidazole.
Cryptosporidium Paromycin
parvum
Oro-fecal Diarrhea Ooocysts in stool
(investigational)
Isospora belli Oro-fecal Giardiasis-like Ooocysts in stool Sulpha drugs
Trichomonas Vaginitis; occasional Flagellate in vaginal Mebendazole; vingar
vaginalis
Sexual urethritis/prostatitis. (or urethral) smear. douche; steroids
9. Entamoeba histolytica
Causes disease of the large intestine –
amoebic dysentery – wherein trophozoites
feed on RBC causing ulcers. Also the liver
and lung abscesses are possible
Naegleria – free-living amoeba in hot
water sources. Causes primary amoebic
meningoencephalitis ( PAM)
Acanthamoeba – free living amoebas
10.
11. AMOEBIASIS (amoebic dysentery,
amoebic hepatitis)
Trophozoite: This form has an ameboid
appearance and is usually 15-30 micrometers in
diameter, although more invasive strains tend to
be larger. The organism has a single nucleus with
a distinctive small central karyosome. The fine
granular endoplasm may contain ingested
erythrocytes. The nuclear chromatin is evenly
distributed along the periphery of the nucleus.
Cyst: Entameba histolytica cysts are spherical,
with a refractile wall; the cytoplasm contains dark
staining chromatoidal bodies and 1 to 4 nuclei
with a central karyosome and evenly distributed
peripheral chromatin
12. Flagellates
Giardia lamblia
- a human parasite of the
gastrointestinal tract. The
organism is spread by direct
contact or through contaminated
food and water.
Giardia spp. are pear-shaped,
with hair-like flagella for motility.
They cause the disease giardiasis
(or lambliasis), an infection of
the small intestine most common
in tropical areas.
Giardia spp. attaches by means
of sucking discs to microvilli in
the human intestine. Abdominal
cramps, swelling, diarrhea and
nausea may occur
13. Balantidium coli
This is a parasite primarily of
cows, pigs and horses. The
organism is a large (100 x 60
micrometer) ciliate with a
macro- and a micro-nucleus .
The infection occurs mostly in
farm workers and other rural
dwellers by ingestion of cysts in
fecal material of farm animals.
Man-to-man transmission is rare
but possible. Metronidazole and
iodoquinol are effective.
14. Trichomonas vaginalis
Trophozoite with undulating membrane
and polar flagella
Presents with fishy-smelling yellow
discharge (guess where)
Males usually asymptomatic
Sexually transmitted
15. Organism Transmission Symptoms Diagnosis Treatment
S. mansoni, skin penetration Dermatitis, abdominal Eggs in stool Praziquantel
pain, bloody stool,
S. japonicum by cercaria
peri-portal fibrosis,
hepato-splenomegaly,
ascites, CNS
Schistosoma skin penetration Dermatitis, urogenital Eggs in urine Praziquantel
cystitis, urethritis and
hematobium by cercaria
bladder carcinoma
Fasciolopsis Metacercaria on Epigastric pain, Eggs in stool Praziquantel,
nausea, diarrhea,
buski water chestnut
edema, ascites
C. sinensis, Cysts in fish Inflammation and Eggs in stool Praziquantel
deformation of bile
O. felinus, or O.
duct, hepatitis, anemia
viverini and edema
Cough (dry / rusty
brown sputum),
Paragonimus
Cyst in crab meat pulmonary pain, Eggs in sputum Praziquantel
westermani pleurisy, tuberculosis-
like
22. Organism Transmission Disease/ Diagnosis Treatment
symptoms
Trypanosoma Tsetse fly. Sleeping Hemoflagellate in Blood stage:
brucei sickness; cardiac blood or lymph Suramin or
failure. node. petamidine
isethionate;
T. cruzi Reduvid (kissing) Chagas disease: Hemoflagellate in CNS:
bug. megacolon, blood or tissue. melarsoperol
cardiac failure. Nifurtimox and
Benzonidazole.
Leishmania Sand fly Visceral leish- Intracellular Pentosam;
donovani maniasis, (macrophages) Pentamidine
granulomatous leishmanial isethionate.
skin lesions. bodies.
L. tropica Sand fly. Cutaneous As for L. As for L.
lesions. donovani. donovani.
L. braziliensis Sand fly Mucocutaneous As for L. As for L.
lesions. donovani. donovani.
25. Organism Transmission Disease/ Diagnosis Treatment
symptoms
Plasmodium Female Malarial Plasmodia in rbc, Quinine
falciparum anopheline paroxysm: chills, typical of the derivatives
P. ovale, mosquito. fever, headache, species involved. Proguanil
P. malariae and P.
nausea cycles. Lariam
vivax
Babesia microti Tick Hemolytic Typical organism None; self
anemia, (Maltese cross) in resolving.
Jaundice and rbc.
fever
Toxoplasma Oral from cat Adult: flu like; Intracellular (in Sulphonamides,
gondii fecal material; congenital: macrophages) pyemethamine,
or meat abortion, tachyzoites. possibly
neonatal spiramycin (non-
blindness and FDA).
neuropathies.
Trimethoprim and
Pneumocystis Pneumocystis in
Cough droplets Pneumonia sulphamethoxazo
jiroveci sputum.
le.
26. Sporozoans
Cryptosporidium parvum – found in
waters, a self limited diarrhea
Plasmodium species cause malaria
Anopheles mosquito as vectors
Complicated life cycle.
P. vivax, P. ovale, P. malariae, P. falciparum
Toxoplasma gondii – reservoir in cats
Human ingest cyst from cats feces or
undercooked meat. Danger in fetus
development
41. Organism Transmission Symptoms Diagnosis Treatment
Epigastric pain, Proglottids or
Tenia saginata Cyst in beef vomiting, eggs in stool or Praziquantel
diarrhea perianal area
Epigastric pain, Proglottids or
Tenia solium Cyst in pork vomiting, eggs in stool or Praziquantel
diarrhea perianal area
Muscle pain and
Roentgenograph
weakness,
T. solium y, anti-
Oro-fecal ocular and Praziquantel
Cysticercosis cysticercal
neurologic
antibody (EIA)
problems
45. Organism Transmission Symptoms Diagnosis Treatment
Abdominal pain,
loss of weight,
Proglottids or
anorexia,
D. latum Cyst in fish eggs in stool or Praziquantel
malnutrition and
perianal area
B12 deficiency
problems
Large cysts
Roentgenograph Surgery,
produce various
y, anti-hydatid formalin
symptoms
E. granulosus Oro-fecal fluid antibody injection and
depending on
(EIA), Casoni drainage,
the location of
skin test Praziquantel
the organism.
Surgery,
E. multiloculoris Oro-fecal As above As above
Albendazole
