Cryptosporidium species causes diarrhoeal
Both the parasite and the disease are
commonly known as "Crypto.“
Water (drinking water and recreational water)
is the most common method of transmission.
Cryptosporidium parvum and C. hominis are
the most prevalent species.
Morphological form detectable in faeces is
measures 4-5 m in diameter
spherical or ovoidal in shape
contains four crescentic sporozoites and amylopectin
like granules (1-6 large dark granules).
Two types :
thin walled (autoinfection)
thick walled (faeces)
Incubation period : 4 to 22 days after ingestion of
Self-limited diarrhoea lasting 5 to 14 days.
diarrhoea is cholera-like, profuse, watery, and foul
smelling, with no leukocytes or blood.
Other symptoms :
Nausea and vomiting, abdominal cramps, low-grade
fever, anorexia, dehydration, weight loss, weakness,
myalgia, and headache.
Patients with profound immunosuppression (AIDS) :
Fluctuation with changes in CD4 count and
The 4 patterns of clinical syndromes are chronic
diarrhoea, cholera-like disease, transient diarrhoea, and
Have a greater incidence of infection in extraintestinal
sites, such as the stomach, and the biliary, pancreatic,
and respiratory tracts.
Sputum – in respiratory cryptosporidiosis
Biopsy – for histopathological examination
Blood – for detection of antibodies
3 consecutive stool specimens to be examined
Direct wet mount of stool for demonstration of highly refractile,
Staining by Modified Ziehl-Neelsen Stain
Immunofluorescent Antibody test
Concentration by Sheather’s sugar concentration technique
Antigen detection in faeces by Immunochromatic test
Histopathological examination –intestinal biospy by H/E stain
Polymerase Chain Reaction (PCR)
Oocysts in stool are stained by a variety of techniques:
modifed cold Kinyoun acid-fast
ﬂuorescent acridine orange
Oocysts are autoﬂuorescent.
On phase-contrast microscopy, oocysts are bright,
refractile, have up to 6 black granules, and often
adhere to mucus.
Differential staining :
Grocott’s methenamine silver (GMS)
Warthin-Starry silver impregnation stain (WS)
Brown-Hopps (B&H) tissue gram stain
Cryptosporidium parvum of calves. Fecal ﬂoat with
refractile unstained oocysts suspended in water
Cryptosporidium parvum in centrifuged human faeces
stained with modified cold Kinyoun acid-fast.
Fecal ﬂoat with unstained oocysts suspended in sugar
solution and viewed with phase-contrast microscopy
Fecal ﬂoat with oocysts stained with monocloanal
antibody conjugated with ﬂuorescent isothiocyanate.
There are several treatments for
Drugs such as nitazoxanide have been used in
children and adults.
Other drugs that are sometimes used include:
The Milwaukee Outbreak
•massive cryptosporidiosis outbreak
following spring thaw
• >400,000 people may have been affected
• based on clinical symptoms (acute watery
•treated water had high levels of turbidity
• oocysts identified in ice made during this period
• 100-fold higher prevalence of Cryptosporidium
oocysts in stools
• other enterics (including Giardia, bacteria,
viruses) were at ~normal levels
Sporozoan of human intestine.
Occurs throughout the world.
Most common in patients with
First described byVirchow in
1860 & named byWenyon in
It causes Isosporiasis which is a
human intestinal disease.
Infection causes acute, non-bloody
diarrhoea with crampy abdominal pain.
Can last for weeks & result in
malabsorption & weight loss.
Oocysts of Isospora belli – elongate-
Measuring – 22 to 33 μm × 10 to 15 μm.
Each oocyst is surrounded by thin, smooth,
two layered cyst wall.
Immature oocyst seen in faeces of patients
contains two sporoblasts.
Life cycle of Isospora belli completes in one
Humans acquire infection by ingestion of
food and water contaminated with faeces
containing sporulated (mature) oocysts.
8 sporozoites are released in the small
intestine & invade the epithelial cells of
distal duodenum & proximal jejunum.
Now they undergo asexual multiplication to
Trophozoites undergo sexual cycle (gametogony)
to produce microgamete & macrogamete.
These microgamete & macrogamete upon
fertilisation form oocysts which are excreted in
Usually oocysts consist of single sporoblast but
soon it divides into two.
These oocysts mature outside the
host and develop into mature oocyst.
These mature oocyst is the infective
stage of the parasite.
Isospora belli infects both
immunocompetent adults & children.
It may lead to mild, self limiting
diarrhoea which lasts for 6 weeks to 6
Dehydration follows when diarrhoea
Oocysts of Isospora Belli in the stool
establishes the diagnosis.
1- Smear can be prepared by Zinc
Sulphate or formalin-ether
2- By acid fast staining or with
Auramine Rhodamine. It appears red
3- Unstained oocysts are
They appear violet under UV light &
green under green or blue-violet light.
Lab Diagnosis Cont…..
POLYMERASE CHAIN REACTION
Highly sensitive and specific method.
Cotrimoxazole is usually effective.
Phylum : Microspora
Obligate, intracellular spore forming
There are at least 15 microsporidian species
that have been identified as human
Nodular Cutaneous Microsporidiosis of the leg caused by
Encephalitozoon intestinalis in an HIV positive patient.
Unicellular, obligate intracellular parasites.
In host cell, the parasite develops and multiply
fission) and produces large number of spores
Spore is the infective stage, measures 0.5-0.2 m x
1-4 m; oval to cylindrical in shape; possess a thick
double layered wall.
Within cytoplasm, spore contains a coiled polar
tube which uncoils and thrusts forcefully into
the host cell and injects sporoplasm (infective
Stained with Gram’s stain, PAS, Giemsa stain or
modified trichome stain.
Gram-positive and acid fast.
Electron micrograph of Anncaliia (Brachiola, Nosema) connori
spore in adrenal gland showing the coiled polar filament
(arrow) and two nuclei.
Species and Genera :
There are 15 genera which infect the humans :
Anncaliia (formerly Brachiola) algerae
Vittaforma corneae, and
Spore of Enterocytozoon bieneusi demonstrating the
characteristic six turns of the polar tubule, which are
organized into two tiers of three turns each.
• Microsporidia have been reported as pathogens in patients
with HIV disease.
• Infection is probably by ingestion, inhalation or inoculation of
• Microsporidia species frequently associated with AIDS are :
• Enterocytozoon bieneusi
• Enchepalitozoon hellem
• Encephalitozoon intestinalis
• Intestinal microsporidiosis – commonest infection caused
mainly by E. bieneusi.
Microsporidian species Clinical manifestation
Anncaliia algerae Keratoconjunctivitis, skin and deep muscle infection
Enterocytozoon bieneusi* diarrhoea, acalculous cholecystitis
Encephalitozoon cuniculi and
Keratoconjunctivitis, infection of respiratory and
genitourinary tract, disseminated infection
Encephalitozoon intestinalis (syn.
Infection of the GI tract causing diarrhoea, and
dissemination to ocular, genitourinary and respiratory
Microsporidium (M. ceylonensis
and M. africanum)
Infection of the cornea
Nosema sp. (N. ocularum),
Pleistophora sp. Muscular infection
Muscular infection, stromal keratitis, (probably
Tubulinosema acridophagus Disseminated infection
Vittaforma corneae (syn. Nosema
Ocular infection, urinary tract infection
Small Intesinal Biopsy – for histopathological examination
Intestinal microsporidiosis – most common type of infection
Diagnosed by microscopy of small intestinal biopsy sections.
Light microscopic and electron microscopic examinations used for
demonstration of spores.
Brown-Brenn or Brown –Hopps tissue Gram stain, PAS or Giemsa
stains- used for demonstration of tiny intracytoplasmic spores.
Spores detected in faeces and content of duodenum-jejunum using
Culture – culture of spores.
Polymerase Chain Reaction (PCR) – Microsporidial DNA
amplified and detected.
For treatment of intestinal microsporidiosis :
For treatment of microsporidial
It is a newly recognised protozoan
Causes a disease named as
Cyclosporiasis in man particularly in
patients with AIDS.
First human case was reported in
Peru in 1995.
In recent years human cyclosporiasis
has emerged as an important
The morphological form found in the
faeces is an oocyst.
Oocyst is non- refractile, spherical.
Diameter- 8 to 10 μm.
Oocyst contains 2 sporocysts.
Each sporocyst contains 2 sporozoites.
Each sporulated oocyst are passed in the
Source- Contaminated food & water
Host- Single host.
Has both sexual & asexual stage.
Man is infected by ingestion of food &
water contaminated with faeces.
The unsporulated oocyst in
faeces sporulates outside the
Excystation of the sporocyst
releases 2 sporozoites which
infect the small intestine causing
Incubation period- 1 week.
Disease starts with acute watery diarrhoea
with nausea, loss of appetite, abdominal
pain, fever fatigue, weight loss.
Diarrhoea may be prolonged & associated
with muscle pain, vomiting, dehydration &
substantial weight loss.
Illness may last six weeks
If the disease is left
untreated, the illness may
Diagnosis- Made by stool sample.
To detect oocysts in faeces, conc. of faeces by
floatation technique is required.
Modified ZN staining is another useful method.
Oocysts are acid fast & stain red in colour.
TAKE HOME MESSAGE AND SUMMARY
Acid fast Intestinal parasites
Persistent diarrhoea – HIV/AIDS
Cryptosporidium spp. – Oocyst
Cyclospora spp. – Oocyst
Isospora spp. – Oocyst
Microsporidium Spp. - Spores