s4 l5 schistosoma

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S4 L5: Schistosoma (Blood Flukes) by Dr. Mary Antonette Madrid JJJaaannnuuuaaarrryyy 222666,,, 222000111111

SCHISTOSOMIASISCaused by digenetic blood trematodes.

The three main species infecting humans are1.Schistosoma haematobium ( bilharzia worm)2.Schistosoma japonicum (Japanese blood fluke)3.Schistosoma mansoni. (Mansons blood fluke)

Two other species, more localized geographically, are S. mekongiandS. intercalatum.

In addition, other species of schistosomes, which parasitize birds and

mammals, can cause cercarial dermatitis in humans.

Schistosoma japonicum

Oriental blood flukeEndemic in China, Philippines, Sulawesi and Indonesia

In the Phil., the first report of schistosomiasis was made by Woolley in1906Strains from different geographic areas are distinct although ALLrequire Onchomelaniasnails as intermediate host

Wide range of hostoDogs, pigs, cats, carabaos, cows, rodent, monkeys

found to be naturally infectedSome hosts such as humans, monkey, rabbits, and mice areconsidered permissive hosts (S. japonicum matures and oviposits overextended periods)

Adult and female worms are primarily parasites of the portal vein andits branches

Females: lay up to 200 immature eggs in the branches of the portalvein which require 10-12 days to mature

Eggs escape through ulcerations into the intestinal lumen exportedto fecesEmbryonated egg comes in contact with water hatches liberatesmiracidium

Miracidia infect snail (intermediate host: Oncomelania hupensisd i) d d l i t t

Bulinus sp. Biomphalaria sp.

- Eggs are eliminated with feces or urine; eggs hatch and release miracidia,which swim and penetrate specific snail intermedicate hosts.

- Stages in the snail include 2 generations of sporocysts and the production ofcercariae.

- Upon release from the snail, the infective cercariae swim, penetrate the skinof the human host and shed their forked tail, becoming schistosomulae.

- Schistosomulae migrate through several tissues and stages to their targetresidence in the veins.

- Adult worms in the human reside in the mesenteric venules in variouslocations; females deposit eggs in the small venule of the portal and

perivesical systems and are moved progressively toward the lumen of the

small intestine (S mansoni & S japonicum) and of the bladder and ureters

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d i) d d l i t tsmall intestine (S. mansoni & S. japonicum) and of the bladder and ureters

Male: shorter, sturdier; measures 12-20mm in length by 0.4 to 0.5mm

diameter

o Has a gynecophoral canal where the longer femaleis held

o Testes arranged in one row above the ventralsucker

Female: 15 -26 mm by 0.3mm

o Single pyramidal ovary located in the midlineWorms ingest RBC and possess a protease that breaks down globulin

and hemoglobin

Utilize glucose and are presumed to absorb nutrients through the body

wall

GEOGRAPHIC DISTRIBUTION

S. mansoniis found in parts of South America and the Caribbean, Africa,

and the Middle East;

S. haematobium in Africa and the Middle East

S. japonicum in the Far East.

S. mekongiand S. intercalatum are found focally in Southeast Asia and

central West Africa, respectively.

In the Philippines, there are 24 endemic provinces

o Includes Sorsogon, Oriental Mindoro, Samar, Leyte, Bohol and allprovinces in Mindanao island except Misamis Orientalo Highest prevalence of infection is in children 5-15 years of age

PATHOLOGY OF SCHISTOSOMES

S. mansoniand S. japonicum schistosomiasisincludes:

Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe

stem periportal fibrosis, portal hypertension, and occasional embolic egg

granulomas in brain or spinal cord.

S. haematobium schistosomiasis includes:

hematuria, scarring, calcification, squamous cell carcinoma, and

i l b li l i b i i l d

2. period ofearly egg deposition and extrusion3. period oftissue proliferation

Early schistosomiasis

Itching, chills, fever, cough

Colonic schistosomiasis

Ulceration caused by eggs result in dysentery or diarrhea

Chronic stage: usually asymptomatic but occasional bouts of diarrhea

may occur

Occasionally chronic colonic schistosomiasis is associated with

malignancies

Hepatosplenic disease

Hepatosplenomegaly, ascites, collateral circulation

Pulmonary schistosomiasis

Principal manifestation is cor pulmonale from obstruction of lung

vasculature due to granuloma formation and fibrosis

Cerebral schistosomiasis

Acute stages present with fulminating meningoencephalitis with fever,

headache, confusion, lethargy and coma

Chronic cases: gives a clinical picture of a tumor with localizing signs andinc. intracranial pressure

Among Filipinos, cerebral schistosomiasis is associated with pathology in

other organs (liver and intestines)

CLINICAL FEATURES

Many infections are asymptomatic.

Acute schistosomiasis (Katayama's fever) may occur weeks after the

initial infection, especially by S. mansoniand S. japonicum.Manifestations: fever, cough, abdominal pain, diarrhea,

hepatospenomegaly, and eosinophilia.

Occasionall, central nervous system lesions occur.


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severity of infection. The disease has caused a stunting of the boy's growth, he is only

120cms tall and weighs 22 kg. WHO/TDR/Crump

(Left) A 13-year-old boy with schistosomiasis, hepatosplenomegaly, ascites,

muscle atrophy, pyrexia, anaemia and haemorrhage from the gastrointestinal tract.

(Right) Two boys, victims of schistosomiasis showing typical distension of the

abdomen.

LABORATORY DIAGNOSIS

Microscopic identification of eggs in stool or urine: most practical method

for diagnosis

Stool examination: S. mansoniorS. japonicum infection

urine examination: S. haematobium

Eggs can be present in the stool in infections with all Schistosoma

species.

The examination can be performed on a simple smear (1 to 2 mg of fecal

material).

Enhance detection of eggs by repeated examinations and/or

concentration procedures (such as the formalin - ethyl acetate technique)

field surveys and investigational purposes: quantify egg output by using

the Kato-Katz technique (20 to 50 mg of fecal material) or the Ritchie

technique.

Eggs can be found in the urine in infections with S. haematobium

(recommended time for collection: between noon and 3 PM) and with S.

japonicum.

Detection will be enhanced by centrifugation and examination of the

sediment

Currently regarded as the method of choice for the definitive diagnosis of

schistosomiasis in the Philippines

COPT may take more than 2 years to become neg.

LABORATORY DIAGNOSIS

ANTIBODY DETECTION

Can be useful in both in clinical management (e.g., recent infections) and

for epidemiologic surveys

Can be useful to indicate schistosome infection:

1. Patients who have traveled in schistosomiasis endemic areas2. Patients in whom eggs cannot be demonstrated in fecal or urine

specimens

Test sensitivity and specificity vary widely among the many tests reported

for the serologic diagnosis of schistosomiasis and are dependent on boththe type of antigen preparations used (crude, purified, adult worm, egg,

cercarial) and the test procedure.

At CDC, a combination of tests with purified adult worm antigens is used

for antibody detection.

All serum specimens are initially tested by FAST-ELISA using

Schistosoma mansoniadult microsomal antigen (MAMA).

A positive reaction (greater than 8 units/l serum) indicates infection with

Schistosoma species.

o

Sensitivity forS. mansoniinfection: 99%o Sensitivity forS. haematobium infection: 95%o Sensitivity forS. japonicum infection:


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S. japonicum eggs

The egg is typically oval orsubspherical, and has a vestigial spine,

which is better shown in picture below

Schistosoma japonicum eggs are smaller (68 to 100 m by 45 to 80 m)

than those of the other species

S. haematobium eggs

In this species, the eggs are large and have a prominent terminalspine at the posterior end.

Length 112 to 170 m. greater magnification shows the miracidium inside the egg.

TREATMENT

Safe and effective drugs are available

Drug of choice: Praziquantel

DETOX CORNER

Try answering the situation below.

MIDNIGHT CALLER

As you fall asleep, you enter what could be called another world, as far from

this one as any distant star. In that remote space, even familiar voices and sounds seem

alien and strange. It is a world utterly removed from the one where we spend our waking

hours, a world where the mind is free to roam.

You are lying in bed in that foggy zone between consciousness and sleep,

when the telephone at your bedside rings. It takes you a tremendous effort to reach out

for the receiver, almost as if you were moving underwater. You fumble to get the rightends aligned with your mouth and ear and manage to mumble, Hello? Who is the voice

on the other end of the line, and what does that person say to you?

..........

.........

........

.......

......

.........

...

..

.

Siret na?

KEY TO MIDNIGHT CALLER

Being awakened suddenly from a slumber is disorienting andsometimes a little bit scary. Its a natural instinct to turn to others for help whenyoure confused or afraid. So although the ringing phone is the cause of yourconfusion, the voice you hear on the line is actually someone you depend on in

difficult times.Whom did you name,and what words of reassurance did they offer


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Criteria S. japonicum S. mansoni S. haematobium

Geographical distribution China, Indonesia, Japan and Philippines (Mindoro, Samar, Leyte,Sorsogon, Mindanao)

Africa, South America Africa, Middle East

Common name Oriental Blood Fluke Mansons Blood Fluke Vesical Blood Fluke

Habitat Superior mesenteric veins Inferior mesenteric veins Vesical veins (venous plexus of the bladder)

Disease Caused Oriental Schistosomiasis/ Katayamas disease Intestinal Bilharziasis/ Schistosomal Dysentery Urinary Bilharziasis/ Schistosomal hematuria

Symptoms Dermatitis, abdominal pain, bloody stool, peri-portal fibrosis,hepatosplenomegaly, ascites, CNS

Dermatitis, abdominal pain, bloody stool, peri-portalfibrosis, hepatosplenomegaly, ascites, CNS

Dermatitis, urogenital cystitis, urethritis and bladdercarcinoma

Mode of transmission Skin penetration of cercariae in infected waterSnail intermediate host Oncomelania quadrasi Biomphalaria spp., Planorbis, Tropicorbis Bulinus, Physopsis

Infective stage Cercariae

Diagnostic stage Eggs in stool

Ova Oval; w/ small lateral spine; may appear as a small hook orknob located in a depression in the shell; tissue or red cekks maybe adherentSize: 55-65 x 70-100 um

Elongated; prominent lateral spine near posterior end;anterior end tapered and slightly curved

Size: 45-70 x 115-175 um

Elongated; rounded anterior end; terminal spine atposterior end.

Size: 55-65 x 110-170 um

Adult skin Smooth With course tuberculations With fine tuberculations

Number of testes in adultmales

6-7 4-5 8-9

Location of the ovary inadult female

Median Anterior Posterior

Number of eggs produced byadult female

50-100 20-30 1-4

Uterus in adult females Long and well developed Short Long

Specimen for diagnosis Feces/ Stool Feces/ Stool urine

Specific features andvarieties

Often coated with debris and may be overlooked Eggs discharged at irregular intervals ; may not be found instool. Are rare in chronic stages of infection

eggs often covered with debris

Stage of Development whenpassed

Embryonated. Contains mature miracidium

Treatment Praziquantel

Prevention and control Chemotherapy in high prevalence areas, health education, control ofOncomelania quadrasisnails, sanitary disposal of feces

Additional:

SPECIES SHAPE STAGE OFDEVELOPMENTWHEN PASSED

SPECIFICFEATURE AND

VARIETIES

Schistosomaintercalatum

Elongated; w/tapered anterior end& terminal spine;

sometiimes spindle-shaped

Embryonated.Contains maturemiracidium

Terminal spine long,slender with bent tip;resembles S.

Haematobium eggexcept it is longer,thinner and haslonger spine; foundin feces; debris mayadhere to shell

** Source: From theLecture, Laboratory notes and CEU College of Medical Technology Parasitology Review Notes by Ma. Cristina Liwanag

s4 l5 schistosoma

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