8 schistosomiasis
-
Upload
hari-dadeeswaran -
Category
Documents
-
view
246 -
download
1
Transcript of 8 schistosomiasis
-
8/6/2019 8 schistosomiasis
1/59
-
8/6/2019 8 schistosomiasis
2/59
Once known as bilharzia/bilhariasis. It was named after
Theodor Maximilian Bilharz.
1st to describe the ailment in men in 1851 at the Kasr-el-Aini in
Cairo, Egypt.
Schistosome eggs were found in ancient Chinese and Egyptian
mummies by Sir Armand Ruffer in 1910 (SRG).
S. haematobium, first species to be discovered.
S. japonicum, named by Fijiro Katsurada, Professor of
Medicine at Okayama Medical School. S. mansoni, discovered in 1907.
S. mekongi, officially named in 1978.
S. intercalatum, officially named in 1934.
-
8/6/2019 8 schistosomiasis
3/59
Species Geographicaldistribution
Intestinal S. S. mansoni Africa, Middle East,Caribbean, Brazil,Venezuela, Suriname
S. japonicum China, Indonesia,Philippines
S. mekongi Cambodia, Lao
S. intercalatum Rainforests of centralAfrica
Urogenital S. S. haematobium Africa, Middle East
-
8/6/2019 8 schistosomiasis
4/59
They belong to Genus Schistosoma, live in blood vessels and cause
schistosomiasis. People call them blood flukes. There are four species
infecting human body. They are:
1. Schistosoma japonicum is prevalent in Far East. In china, it is
prevalent in Yangtze valley and south of Yangtze except Guizhou Province.
The adults live in the portal vein system, causing liver cirrhosis and portal
vein hypertension syndrome.
22. Schistosoma mekongi is merely distributed in Mekong River Valley,resembles Schitosoma japonicum except intermediate host.
3. Schistosoma haematobium widely spreads in Africa, chiefly in Nile
River valley. The adults live in the vesical and pelvic plexus causing painless
terminal haematuria, renal failure complicated by the ureter obstruction. In
the endemic area infection is so common that hematuria is accepted as a sign
of manhood in young boy.
4. Schistosoma mansoni is distributed in Africa and focal area in Latin
America. Lives in the portal and hemorrhoidal vein plexus, causing stool with
fresh blood, liver cirrhosis and portal vein hypertension.
-
8/6/2019 8 schistosomiasis
5/59
-
8/6/2019 8 schistosomiasis
6/59
I. Morphology
1. Adult worms are elongated cylindrical in shape,unlike other flukes. Two sexes are separate, gray white
in color, but the female is much dark and slender, the
male is shorter and thicker, sickle-like. In human body
the male usually embraces the female into itsgynecophoral canal, appears K like (or the female
usually resides in males gynecophoral canal).
Schistosoma japonicum
-
8/6/2019 8 schistosomiasis
7/59
Female: Longer and slender than the male, much dark colored thread-like,
12-26 x 0.1-0.3mm in size. The digestive system is similar to that of male.
The vitellaria are located in the posterior part of the body surrounding
the cecum. The unbranched, oval ovary lies in the mid-portion of the body.
The uterus lies in the anterior portion of the body filled with 50-300 eggs
arranged in a single row, arising from ootype to genital pore behind the
ventral sucker.
Male: 10-20 x 0.5-0.5 5mm in size, oral sucker at top near by ventral sucker. Just
behind the ventral sucker there is a longitudinal groove-gyncophoral canal in
which the female normally resides. The esophagus is divided into two branches in
front of the ventral sucker, and then unite to form a cecum at the posterior third
part of the body. Seven testes are situated one by one, each has a delicate efferens
which combine to form the vas deferens and dilate to become a seminal vesical
opening in the genital pore just behind ventral sucker.
-
8/6/2019 8 schistosomiasis
8/59
-
8/6/2019 8 schistosomiasis
9/59
-
8/6/2019 8 schistosomiasis
10/59
Paired male and female adult worms. The
female schistosomulum is the darker, curledworm within the male's gynacophoric canal.
-
8/6/2019 8 schistosomiasis
11/59
2. Mature egg is oval in shape, slight yellow in color, 89 x 67,
shell is thin without an operculum but with a lateral spine.
The content is a miracidium. Under the electron microscope
there are many micro-tubules on the shell, through which the
soluble egg antigen (SEA) is secreted by a miracidium.
3. Cercaria is infective stage. It is composed of the body and
forked tail (including tail stem and fork) and has 5 pairs of
penetrating glands in the body (2 pairs of preacetabular and 3
pairs of postacetabular glands)
-
8/6/2019 8 schistosomiasis
12/59
Oval in shape, slight
yellow in color, 89 x
67 , shell is thin
without an
operculum but with
a lateral spine.
-
8/6/2019 8 schistosomiasis
13/59
The small spine is
generally not visible as
the egg surface is often
covered with facal
debris.
-
8/6/2019 8 schistosomiasis
14/59
Forked cercaria of S.
japonicum
-
8/6/2019 8 schistosomiasis
15/59
1. Site of inhabitation: the portal vein system, mainly in theinferior mesenteric vein.
2. Infective stage: cercaria
3. Infective route: by skin
4. Intermediate hosts: Oncomelania snail5. Reservoir hosts: mammals such as buffalo, cattle, wild
rodents, goat, monkey, pig, fox.
6. Eggs are main pathogenic factor: (They are inlaid in theliver and intestinal wall. Some of them are discharged in feces
to complete its life cycle).7. The development in human body requires 25-30 days.
Cercaria can live 1-3 days. Life span of the adults is about 20-30 years.
-
8/6/2019 8 schistosomiasis
16/59
88. Blood fluke is a special kind of flukes because of
following characters:
(1) The adult worms look like nematodes, elongated
cylindrical in shape.
(2) Two sexes are separate.(3) Egg without operculum, but with a lateral spine.
(4) Only one intermediate host required.
(5) The infective stage is cercaria.
(6) The infective route is by skin.
(7) The eggs are main pathogenic stage.
-
8/6/2019 8 schistosomiasis
17/59
Three major factors responsible for theoccurance of schistosomiasis:
The method of disposal of human excreta
The presence of the snail intermediate host
The contact with cercaria-infected water
-
8/6/2019 8 schistosomiasis
18/59
adult worm passing eggs
egg into fresh water
cercariae
miracidia
penetrate into the body of the snail
(intermediate host)
oncomelania
-
8/6/2019 8 schistosomiasis
19/59
-
8/6/2019 8 schistosomiasis
20/59
-
8/6/2019 8 schistosomiasis
21/59
The intermediate host of S. japonicum: Oncomelania
snail
-
8/6/2019 8 schistosomiasis
22/59
1. Pathogenic mechanism of blood fluke
(1) Due to the cercaria and schistosomulum ( adolescent ) :
When human schistosome cercaria repeatedly penetrate the
human skin, type I allergy takes place. The cercarial dermatitis appears ,
petechiae and rashes ensue. The migration of the adolescents may inducelocalized pneumonitis and urticaria
(2) Due to adults:
The mechanical effect and toxic effect of adults and their
metabolites cause mesenteric phlebitis, hepatitis, and abdominal pain; the
immune complex may cause the damage to the kidney, schistosome
nephritis results from type III allergy, the esinophils increase in
peripheral blood.
III. Pathophysiology and clinical manifestation
-
8/6/2019 8 schistosomiasis
23/59
(3) Due to eggs:
The most serious damage is done by eggs. Colon and liver are most
seriously involved.
1) In liver: Soluble egg antigen Eosinophilic infiltration
Granuloma Eosinophilic abscess formation Fibrosis
Liver cirrhosis (pipestem fibrosis)
splenomegaly
Portal vein hypertension ascites esophageal varicosity
hemorrhoid varicosity
varicosity varicosity surrounding
the umbilicus
-
8/6/2019 8 schistosomiasis
24/59
2) In intestine
Soluble egg antigen Eosinophilic
infiltration Granuloma
Eosinophilic abscess UlcerationFibrosis or polyp
-
8/6/2019 8 schistosomiasis
25/59
(1) Initial phase: It is characterized by fever, dry cough
(pneumonitis), urticaria, eosoniphilia. These phenomena are due toadolescents migration.
(2) Acute stage: The characteristics symptom is dysentery.The patient may pass stool with blood, pus and mucus 5-10 timesper day, in which a large number of eggs can be found. Chills, fever,and malaise occur.
(3) Chronic stage: Chief manifestations of the patients are
interval diarrhea or dysentery. The patients experience fatigue,general condition and strength deteriorate, loss of weight andinterest, retardation of both physical and mental growth in children.Spleen and liver enlargement, anemia, in women menopause,sterility and abortion may occur. This stage may last from several
years to 20 years.
2. Clinical manifestation (symptoms and signs)
-
8/6/2019 8 schistosomiasis
26/59
(4) Terminal stage is characterized by portal vein
hypertension syndrome, common saying, abdomendistention looks like a big drum, emaciation looks like a
fire wood. Ascites, emaciation, varicosity, splenomegaly
and anemia are commonly found. The patients die of
secondary infection, upper digestive tract bleeding,
hepatic coma.
(5) Ectopic lesion: The damage to the central nervous
system ( brain, spinal ) may cause paralysis (monoplegia,
hemiplegia ).
-
8/6/2019 8 schistosomiasis
27/59
abdomen distention looks
like a big drum, emaciationlooks like a fire wood. Ascites, emaciation,varicosity, and splenomegaly
-
8/6/2019 8 schistosomiasis
28/59
-
8/6/2019 8 schistosomiasis
29/59
-
8/6/2019 8 schistosomiasis
30/59
-
8/6/2019 8 schistosomiasis
31/59
Acute stage: eosinophilia is characteristic change.WBC raise to 10-
30G/L
Chronic stage: eosinophil ia (slightly or moderate rise in eosinophils)
Terminal stage: WBC and platelets are lower
Acute stage: rise in serum globulin, slight rise in ALT
Chronic stage: most patients have a normal liver function,
especially asymptomatic
Terminal stage: serum ALB descends caused by liver cirrhosis
-
8/6/2019 8 schistosomiasis
32/59
The discovery of eggs in stool is the evidence of
diagnosis by direct smear or other methods
Imaging testB-ultrasound: the degree of liver cirrhosis
CT: the image of liver and brain
X-ray: chest; esophagus; and gastrointestinal tract
-
8/6/2019 8 schistosomiasis
33/59
Immunological Tests
Intracutaneous test
Circumoval precipition test
ELISA and IHA etc.
Monoclonal antibody technique
-
8/6/2019 8 schistosomiasis
34/59
Varicosity of esophagus-fundus-stomach
Hemorrhage of upper gastrointestinal tract
Hepatic encephalopathy (HE)Spontaneous bacterial peritonitis (SBP)
Complications of intestinal tractAppendicitis
Intestinal obstruction and cancroid change
-
8/6/2019 8 schistosomiasis
35/59
1. Epidemiological investigation: Investigate whether
Oncomelania snail can exist in local natural environment; local
residents are used to defecate, work and play in the same water;
and examine the pathogen: Examine the feces from local
residents and domestic animals; also can dissect the suspicious
reservoir hosts, such as buffalo, goat, wild rodents and etc. If
the source of infection, intermediate hosts, transmitting route
and susceptible crowd exist at same time and local, an endemic
area of schistosomiasis can be confirmed.
-
8/6/2019 8 schistosomiasis
36/59
2. Eliminate the source of infection
Treat the patients, carriers and domestic animals. Drug of
choice for man: Praziqantel is pretty effective, side effects are
very light. The other effective drugs, such ashexachloroparaxylol, bithionol may be used.
Kill the wild animals which may be infected.
3. Prevention
(1) Health education is in progress, give up habits.(2) Control and deal with night soil.
(3) Avoid directly contacting with the water contaminated by
cercariae, lay up water in a container for 3 days, exposed to sun
shine; put on protective clothes; apply some chemical repellenton the skin (dibutyl phthalate)
(4) Kill the intermediate hosts and wild reservoir hosts.
(5) Change the bad environment, realize modernization of
agriculture.
-
8/6/2019 8 schistosomiasis
37/59
1. Geographical distribution: The disease is prevalent in
China, Japan, Philippines, Indonesia. In China, this
disease is found in 13 provinces, city and autonomic
regions along the Yangtze River Valley and south of the
Yangtze ( north from Jiangsu, Baoying county to southend Guangxi, Heng County ). In Taiwan, only animals, no
humans are infected by S. japonicum.
-
8/6/2019 8 schistosomiasis
38/59
-
8/6/2019 8 schistosomiasis
39/59
33.. Social factors:
(1) Habits: residents are used to defecate, work
and play in the same water. The people whowork on catching fish, planting rice, washing
commodes, vegetables and clothes get
infection easily.
(2) Local economy and culture fall behind..
-
8/6/2019 8 schistosomiasis
40/59
Geographical
distribution of
mansoni
schistosomiasis
Schistosoma Mansoni
-
8/6/2019 8 schistosomiasis
41/59
Life Cycle
-
8/6/2019 8 schistosomiasis
42/59
infective form
cercaria
intermediate host:
snail Biomphalaria
swims freely in
infected waters penetrates the skin
of a definitive host:
man and other
mammals 0,5 cm
-
8/6/2019 8 schistosomiasis
43/59
Pathogenic form
adult female: 1.2 to1.6cm
adult male: 0.6 to 1.4cm
mature female inside
male walls of venules of
sigmoid and rectum
superior hemorrhoidal
plexus branches of inferior
Mesenteric vein
-
8/6/2019 8 schistosomiasis
44/59
Pathogenic form egg
300 eggs / day length: 150
width: 65
lateral spine
-
8/6/2019 8 schistosomiasis
45/59
Clinics
1. Acute phase
cercarial dermatitis
Schistosoma mansoni or other species
2/3 days: localized pruritus, urticarial rash,papuloerythematous exanthem
15 to 25 days: abrupt onset of fever, headache,
shivering, anorexia, myalgia, right upper quadrant
pain, less comonly nausea, vomitting, diarrhea, cough hypersensitivity: urticaria, generalized pruritus,
facial edema, erythematous plaques, purpuric lesions
weight loss, hepatosplenomegaly
-
8/6/2019 8 schistosomiasis
46/59
Clinics
2. Chronic phase
more common forms
intestinal (fatigue, vague abdominal pain,
diarrhea, alternating with constipation,
dysentery-like illness with bloody bowel
movements) hepatosplenic: 4 to 5% severe lesions
(portal hypertension, ascites, pdal edema,
hepatosplenomegaly)
cardiopulmonary
-
8/6/2019 8 schistosomiasis
47/59
-
8/6/2019 8 schistosomiasis
48/59
Cutaneous mansoni schistosomiasis
Genital or vulvar forms
physiopathology
through hemorrhoidal plexus
periovular or
schistosomatic granuloma
Ectopic location of mansoni schistosomiasis
physiopathology unknown
how do eggs/adult worms reach theabdominal wall or other areas ? unknown
erythematous
linear arrangement
almost zosteriform
-
8/6/2019 8 schistosomiasis
49/59
Histopathological examination
Epidermis
papillomatous epithelial hyperplasiaDermis
granulomatous tuberculoid reaction
chronic inflammatory infiltrate
foreign body giant cell
large ovoid structures
Histopathological examination
Dermisovoid structures with
lateral spine dead
and viable eggs
ofS. mansoni
-
8/6/2019 8 schistosomiasis
50/59
Diagnosis
Clinics
Parasites
eggs in fecesbiopsy: rectal, liver and granuloma
Immunology
complement fixation, periovular andcercarial reaction, ELISA, intradermal
reaction, immunofluorescence, PCR
-
8/6/2019 8 schistosomiasis
51/59
Treatment
niridazol
hycanthone
oxamniquine
praziquantel
Prophylaxis
water source
sanitary facilities
control of snails
sanitary education
-
8/6/2019 8 schistosomiasis
52/59
SchistosomaSchistosoma
HaematobiumHaematobium Infects over 111 million people
Mostly in Africa and the Middle East
Most common cause of urinary schistosomoasis
Definitive host: human
Intermediate host: Bulinus species snail
-
8/6/2019 8 schistosomiasis
53/59
Life Cycle
-
8/6/2019 8 schistosomiasis
54/59
Life Cycle
-
8/6/2019 8 schistosomiasis
55/59
Signs and Symptoms
Immediate manifestations:
Cercarial dermatitis:maculopapular blistering eruption
1-2 days after exposure
Lasts for a few days Self-limited
-
8/6/2019 8 schistosomiasis
56/59
Acute Schistosomiasis: Fever, lymphadenopathy, hepatosplenomegaly, blood eosinophilia
Initial allergic hypersensitivity to the parasite as well assubsequent formation of soluble immune complexes
Chronic schistosomiasis: Chronic form develops as many S.haematobium eggs remain
trapped in the host tissues and become surrounded by delayed-type
hypersensitivity granulomatose inflammation
Inflammation is associated with collagen deposition and scar
formation
Gradual accumulation of the scar within bladder and ureterscan lead to hydroureter, hydronephrosis, ascending bacterial
infection
Inflammation can result in local ulceration and significant blood
loss in the urine
Inflammation may be associated with dyserythropoesis
-
8/6/2019 8 schistosomiasis
57/59
For those with less intense exposure the early signs
include: dysuria, proteinuria, bladder polyps
Later signs and symptoms include:
hydronephrosis, hydroureter, bladder calcification,urinary tract infection and squamous cell carcinoma
of the bladder
For hosts with eggs in the bladder and lower
ureters, 50% ofpatients have symptoms of dysuria,frequency and terminal hematuria
Cor pulmonale
Central nervous system disorders
Signs and Symptoms
-
8/6/2019 8 schistosomiasis
58/59
Diagnosis:
Finding of parasite egg in urine or feces
Concentration methods, sedimentation
or membrane filtration techniques
Serologic testing
Radiologic testing
Treatment: praziquantel
Eggs are spindle-shaped,
usually 140-150 by 60
micrometres, they have a
terminal spine
-
8/6/2019 8 schistosomiasis
59/59