TYPES OF HOST

LESSON 1: INTRODUCTION TO PARASITOLOGY ●​ Animals Host

●​ Humans Host
MEDICAL PARASITOLOGY
Types of Parasite Definition / Description
●​ Deals with the parasites, which cause human
infections and the disease they produce Definitive Host Aka Final Host; adult sexual phase of
●​ It is broadly divided into 2 parts: parasite development occurs
○​ Protozoology
■​ study of protozoans Intermediate Asexual or larval phase of parasite
■​ First animals Host development occurs
■​ Protos (first), zoans (animals)
Paratenic Host Parasite does not develop further to
■​ Simple parasites (unicellular in later stages but able to infect another
nature) susceptible host
○​ Helminthology -
■​ Study of helminths Reservoir Host Host that harbor the parasite other
■​ Greek word (worms) than mentioned above
■​ Complex parasites (multicellular in
Transport Host Host responsible for transferring a
nature)
parasite from one location to another

PARASITE-HOST RELATIONSHIPS Accidental Host Other than the normal one that is
Symbiosis - living together of UNLIKE organisms. It may also harboring a parasite
involve protection or other ADVANTAGES to one or both
organism Carrier Parasite-harboring host that is not
exhibiting any clinical symptoms but
can infect others
1)​ Commensalism - a symbiotic relationship in which
two species live together and one species BENEFITS
from the relationship PARASITIC LIFE CYCLES
2)​ Mutualism - a symbiotic relationship in which two 3 Components of parasitic life cycle:
organisms MUTUALLY BENEFIT from each other 1)​ Mode of transmission - transfer parasite to different
3)​ Parasitism - a symbiotic relationship where one host
organism, the parasite, lives in or on another, 2)​ Infective stage - stages of development, that can
DEPENDING on the latter for its SURVIVAL and develop into one host to another
usually at the EXPENSE of the host 3)​ Diagnostic stage - identify morphologically the
parasites harboring in specific host
TYPES OF PARASITE
2 kinds of parasitic life cycle
Types of Parasite Definition / Description 1)​ Direct life cycle - when a parasite requires only A
SINGLE HOST to complete its development
Obligatory Parasite Parasite that cannot survive
outside the host 2)​ Indirect life cycle - when a parasite requires 2 OR
MORE SPECIES OF HOST to complete its
Facultative Parasite Parasite that is capable of existing development
independently of a host

Endoparasite Parasite that is established inside

of a host

INFECTION - presence of
endoparasite

Ectoparasite Parasite that is established in or on

the exterior surface of a host

INFESTATION - presence of
ectoparasite

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

SOURCES OF INFECTION
1)​ Contaminated soil, water, and food
2)​ Vectors - insects, ticks, arthropods
3)​ Animals - domestic or wild animals
4)​ Other person

MODES OF TRANSMISSION
1)​ Oral Transmission (mouth)
2)​ Skin Transmission (directly infect)
3)​ Vector Transmission (vectors)

MODES OF INFECTION
1)​ Direct Transmission (Oral, Sexually, Accidents)
2)​ Vertical Transmission (congenital or transplacental)
3)​ Iatrogenic Transmission (blood transfusion, organ
transplant

DISEASE PROCESSES AND SYMPTOMS

A parasitic disease may affect the entire body or any of its
parts. The major body areas associated with such processes
include the following:
1)​ The gastrointestinal (GI) and urogenital (UG) tracts
2)​ Blood and tissue
3)​ Liver, lung, and other major organs
4)​ Miscellaneous locations - cerebrospinal fluid (CSF),
eye, skin, and extremities

PREVENTIVE AND CONTROL

●​ Morbidity Control - avoidance of illness caused by
infections. It may be achieved by periodically
deworming individuals or groups, known to be at risk
of morbidity
●​ Environmental Management - the planning,
organization, performance, and monitoring of
activities for the modification and/or manipulation of
environmental factors or their interaction with human
beings with a view to preventing or minimizing vector
or intermediate host propagation and reducing
contact between humans and the infective agent
●​ Environmental Sanitation - interventions to reduce
environmental health risks including the safe disposal
and hygienic management of human and animal
excreta, refuse, and wastewater

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 Parameter
LESSON 2: PHYLUM NEMATODA (INTESTINAL) [PART 1]
Size 85 - 95 um by 38 - 45 um Size
NEMATODES variations possible
●​ Most worm-like of all helminths. This is because they
generally resemble the common earthworm in Shape Varies
appearance, which is considered to be the prototype
Embryo Embryonated
of ‘worms’
Amorphous mass of protoplasm
●​ Elongated, cylindrical, unsegmented worms with
tapering ends Shell Thin
●​ Nematode-means thread-like
○​ From nema meaning ‘thread’ Other Usually Corticated

INTESTINAL NEMATODES Ascaris Lumbricoides (Adult)

L1 and L2 L3 and L4 ●​ Ascaris adult worms are the largest known intestinal
nematodes
●​ Immature stage of ●​ Mature stage
Female Adult Male Adult
parasite ●​ Non-feeding stage
●​ Feeding stages ●​ L4 is Adult Stage
Size 22-35 cm Up to 30 cm
○​ Mouth ●​ Filariform
○​ Esophagus
Color Cream white, Pink Cream white, Pink
●​ Rhabditiform
tint tint

Other Pencil lead Prominent incurved

ASCARIS LUMBRICOIDES thickness tail

●​ Common Names: Large intestinal roundworm,

roundworm of man
●​ Causes: Ascariasis, roundworm infection
●​ A soil-transmitted helminth
●​ Ascariasis - considered as the most common
intestinal helminth infection in the world

Ascaris Lumbricoides (Unfertilized Egg)

PATHOPHYSIOLOGY OF ASCARIS
●​ Ascariasis
●​ Usual infection of 10-20 worms may not show
symptoms
●​ Causes Ascaris Pneumonitis - chest pain, cough,
fever, increased eosinophil (with heart to lung
migration)
●​ Lung infection, asthmatic attack and edema of the
lips
●​ Difficulty in breathing

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 ●​ Treatment: Albendazole and Mebendazole Comparison

TRICHURIS TRICHIURA

Common Name: Whipworm

Causes: Trichuriasis or whipworm infection

Trichuris Trichiura (egg)

Parameter

Size 50-55 by 25 um

Shape Barrel, football

Hyaline polar plug at each end

Embryo Unicellular, underdeveloped

Shell Smooth
Yellow-brown color because of bile
PATHOPHYSIOLOGY OF TRICHURIS TRICHIURA
contact
●​ 3rd most common helminth, found primarily in warm
climates
Plug ●​ Poor sanitation practices
(1)​ Portal of entry - nutrients ●​ Symptoms (Children): ulcerative colitis, chronic
(2)​ Protection - chemicals dysentery, severe anemia and possible growth
(3)​ Portal of exit - worm retardation
●​ Rectal prolapse and peristalsis
Trichuris Trichiura (Adult) ●​ Symptoms (Adult): inflammatory bowel disease,
Female Adult weight loss, weakness and mucoid or bloody diarrhea

Size 2.5 - 5 cm long HOOKWORMS

Anterior end Colorless

Resembles a whip handle
Contains slender esophagus

Posterior end Pinkish gray

Resembles whip itself
Contains digestive and reproductive
systems
Males: possess prominent curled tail

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 ●​ The term hookworm refers to two organisms:
○​ Necator americanus
Parameter
○​ Ancylostoma duodenale
●​ Soil-transmitted helminths Size 270 by 15 um
●​ Blood-sucking nematodes that attach to the mucosa 540-700 um long
of the small intestines Newly hatched 5 days old

Hookworms (Egg) Other Long Buccal cavity

Small genital primordium
●​ Ancylostoma duodenale

Filariform Larva

Parameter
○​ Common Name: Old World Hookworm
○​ Causes: Hookworm infection, ancylostomiasis Size Short
○​ Size: 55-60 um
○​ Width: 35-40 um
○​ Shell: colorless Tail Pointed

●​ Necator americanus
Hookworm (Adult)

○​ Common name: New World Hookworm General Characteristics

○​ Causes: Hookworm infection, necatoriasis
○​ Size: 60-75 um Color Grayish-white to pink
○​ Width: 35-40 um
Cuticle Somewhat thick
○​ Shell: Colorless
Anterior end Conspicuous bend, hook

Rhabditiform Larva
Characteristics Female Adults Male Adults

Size 9-12 mm long 5-10 mm long

0.25-0.50 mm 0.2-0.4 mm wide
wide

Other features Prominent

Posterior
Copulatory
bursa

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

Buccal Capsule Characteristics STRONGYLOIDES STERCORALIS

Necator Contains pair of cutting plates

Ancylostoma Contains actual teeth

●​ Common Name: Threadworm, Military Worm

●​ Causes: Strongyloidiasis, threadworm infection
●​ The only species of this genus which is naturally
pathogenic to humans

Strongyloides Stercoralis (egg)

Parameter

Size 48 - 35 um

Typical Growth Phase Contains well-developed larvae

Embryonic Cleavage 2, 4 or 8 cell

PATHOPHYSIOLOGY OF HOOKWORMS
Shell Thin, hyaline

Rhabditiform Larva

●​ Size: 220 by 15 um
●​ Short buccal cavity; prominent genital primordium

●​ Hookworm infection is usually chronic, hence patients

often show no acute symptoms
●​ Patients who are repeatedly infected may develop
intense allergic itching at the site of hookworm
penetration (ground itch)
●​ May develop a microcytic hypochromic iron
deficiency, weakness, and hypoproteinemia

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 PATHOPHYSIOLOGY OF STRONGYLOIDES STERCORALIS
●​ Diarrhea and abdominal pain
Filariform Larva
●​ Exhibit urticaria accompanied by eosinophilia
●​ Length: 690 um ●​ Heavy infections may develop malabsorption
●​ Long esophagus syndrome
●​ Tail is notched ●​ Cochin-China Diarrhea / Vietnam Diarrhea - french
soldiers on duty in Vietnam who had severe diarrhea
●​ Treatment: Ivermectin with albendazole

ENTEROBIUS VERMICULARIS

DIFFERENCE OF HOOKWORM AND STRONGYLOIDES IN

TERMS OF THEIR LARVAL STAGES:

●​ Common Names: Pinworm, Seatworm, Society Worm,

Social Worm, Oxyuriasis
●​ Causes: Enterobiasis, Pinworm Infection

Enterobius Vermicularis (Egg)

Strongyloides Stercoralis (Adult Female)

●​ Parthenogenic
●​ Size: 2 by 0.4 mm
●​ Other:
○​ Colorless, transparent body
○​ Finely striated cuticle
○​ Short buccal cavity
○​ Long and slender esophagus

Parameter

Size 48-60 um long

20-35 um wide

Shape Oval, one-sided flattened

Embryo Stage of development varies

May be embryonated or mature

Shell Double-layered, thick and colorless

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

Enterobius Vermicularis (Adult) PATHOPHYSIOLOGY OF ENTEROBIUS VERMICULARIS
●​ Most common symptoms: intense itching and
inflammation of the anal / vaginal areas. Intestinal
irritation, mild nausea or vomiting, irritability and
difficulty sleeping
●​ Retroinfection - infective pinworm eggs that migrate
back into the host body, develop and reproduce
rather than becoming dislodged
●​ Treatment : Albendazole, mebendazole, or pyrantel
pamoate

CAPILLARIA PHILIPPINENSIS
●​ One of four Capillaria species that are known to infect
Adult Female Adult Male humans
●​ First reported in Northern Luzon
Length 7-14mm 2-4mm
●​ Fish-eating birds are the natural hosts of the
Width Up to 0.5 mm <or = 0.3 mm nematode

Color Yellowish-white Yellowish-white Capillaria Philippinensis (egg)

Tail Pointed
Resembles pinhead

●​ Size: 36 to 45 um by 20 um
●​ Peanut-shaped with striated shells and flattened
bipolar plugs
●​ They must reach the water in order to be ingested by
small species of freshwater or brackish water fish

Capillaria Philippinensis (Adult worm)

●​ Size in Length:
○​ Male - 1.5 to 3.9 mm
○​ Female - 2.3 to 5.3 mm
●​ Has thin filamentous anterior end and a slightly
thicker and shorter posterior end
●​ Stichocytes - rows of secretory cells in esophagus
●​ Stichosome - term for the entire esophageal structure
of C. Philippinensis

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

PATHOPHYSIOLOGY OF CAPILLARIA PHILIPPINENSIS
●​ Intestinal Capillariasis - characterized by abdominal
pain, chronic diarrhea, and gurgling stomach
(borborygmi)
●​ Infections are acquired by eating uncooked small
freshwater/brackish water fish
○​ Example: Ilocano people enjoy eating
“bagsit” and other fishes found in the lagoons
○​ Birut, Bukto, Bagsit, Biyang bato, Ipon,
Guppy

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 Infective form: L3 in the hemocoel of infected copepod
LESSON 3: PHYLUM NEMATODA (EXTRA-INTESTINAL) MOT: Contaminated water containing copepod
[PART 2]

EXTRAINTESTINAL
●​ Infect areas other than the intestine
●​ It can infect skin and brain
●​ Systemic at most
●​ Zoonotic
○​ Human can be an accidental host

OTHER HOOKWORMS (Zoonotic)

●​ Ancylostoma Canicum
○​ Dog hookworm
●​ Ancylostoma Braziliense
○​ Canid and field (cats)
●​ Ancylostoma Ceylanicum
○​ 2nd most common hookworm species
infecting the APC
○​ It can also harbor human
PATHOPHYSIOLOGY OF DRACUNCULUS MEDINENSIS
●​ The fertilized female worms grows in size, matures,
●​ Both tend to cause creeping eruption (cutaneous
and migrates within the connective tissues throughout
larva migrans) rather than intestinal infection
the body, to finally reach a site where it is likely to
○​ This is generally seen when human infection
come into contact with water
occurs with non-human species of nematodes.
●​ Causes blister formation which eventually ruptures,
The worm is unable to undergo normal
discharging a milky-white fluid containing numerous
development and complete its life cycle
L1 stage larvae
●​ No specific dracunculiasis medicines available
MUST REMEMBER PASSWORD OF HOOKWORMS

ANISAKIS SPP.
Anisakis simplex complex: A simplex sensu stricto, A.
02223 pegreffii, A. berlandi (=A. Simplex C)
ABCeyDCan

DRACUNCULUS MEDINENSIS
●​ Common Name: Guinea worm, Fiery Serpent, Dragon
worm
●​ Causes: Dracunculosis, dracunculiasis, guinea worm
infection
●​ The adult females of D. medinensis are usually found
in the subcutaneous tissue of the legs, arms, and back
in man

●​ Common Name: Herring Worm, cod worm, seal worm

●​ Causes: Anisakiasis
●​ Anisakis species are nematode parasites of marine
mammals like dolphins, seals, and whales
Female is viviparous (lays larvae only)
Definitive Host: Man
Intermediate Host: Copepods

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 Parameter Toxocara canis Toxocara cati

Size 80-85 um 65-75 um

Shape Golden in color, spherical to slightly

pear shaped, thick-shelled, and have a
pitted surface

Toxocara spp. ADULT

Parameter Male Female

Size 4-6 cm 6-10 cm

Features Trilobate lips

Large, spear-shaped cervical alae
(broader in T. cati than T. canis
PATHOPHYSIOLOGY OF ANISAKIS SPP.
●​ Abdominal pain, nausea, vomiting within hours of
ingesting the larvae COMPARISON OF E. VERMICULARIS vs TOXOCARA SPP.
●​ Resolves spontaneously after several weeks because
larvae are unable to survive for long periods of time
●​ Treatment: ENDOSCOPICAL SURGERY; Possibly
Albendazole

TOXOCARA SPP. (Ascaris of animals)

●​ Toxocara Canis - dog roundworm
●​ Toxocara Cati - cat roundworm
●​ Toxocara Vitulorum - cattle and water buffaloes

●​ Human infection is by ingestion of eggs

●​ Accidental host

Toxocara spp. OVA

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

PATHOPHYSIOLOGY OF TOXOCARA SPP.
●​ Visceral larva migrans - result of migration and
subsequent death of the larvae in the different tissues
and organs
○​ Wheezing - most common sign
●​ Ocular larva migrans - manifested in the eyes
○​ Unilateral visual impairment sometimes with
strabismus - most common
●​ Covert toxocariasis - less specific syndrome where
most patients are symptomatic and eosinophilia is
less frequent
●​ Neural larva migrans - neurotoxocariasis

TRICHINELLA SPIRALIS
●​ Trichinella Spiralis - carnivorous and omnivorous
animals
○​ Common Name: Pork muscle roundworm,
Trichina worm
●​ Trichinella britovi - carnivores of Europe and western
Asia
●​ Trichinella pseudospiralis - mammals and birds. Do
not encyst in the muscle
●​ Trichinella papuae - wild and domestic pigs in Papua
New Guinea and Thailand. Do not encyst in the muscle
●​ Trichinella nativa - Arctic bears
●​ Trichinella nelsoni - african predators and scavengers
●​ Trichinella zimbabwensis - crocodiles in Africa

Trichinella Spiralis

PATHOPHYSIOLOGY OF TRICHINELLA SPIRALIS

Table 3.4. Algorithm for the diagnosis of the probability of
acute trichinellosis in humans

●​ Female is viviparous Group Symptom

●​ IH AND DH: humans, and other carnivorous and
A Fever, eyelid and/or facial edema, myalgia
omnivorous animals
●​ Infective Form: Encysted larva B Diarrhea, neurological signs, cardiac signs,
●​ MOT: Undercooked meat conjunctivitis, subungual hemorrhages,
cutaneous rash
Trichinella Spiralis ADULT
C Eosinophilia (> 1,000 eosinophils/ml)
Parameter Male Female and/or increased total IgE levels increased
levels of muscular enzymes
Size 0.62-1.58 mm x 1.26-3.35 mm x
0.0.2- 0.033 mm 0.029-0.038 mm D Positive serology (with a highly specific
test). seroconversion , positive muscular
Larva 80-120 um x 5.6 um to 0.026- o.040mm biopsy

Spear-like, burrowing anterior tip

●​ Cardinal signs and symptoms: severe myalgia,
periorbital edema, and eosinophilia
●​ Treatment: Albendazole, Mebendazole

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

ANGIOSTRONGYLUS CANTONENSIS
●​ Former Name: Parastrongylus cantonensis
●​ Common Name: Rat Lungworm
●​ Causes: Human eosinophilic meningitis

Angiostrongylus Cantonensis OVA

Parameter FERTILIZED EGGS

Size 46-48 um x 68-74 um DH: Rats

IH: Slugs and snails (giant african snails)
Shape Elongated, ovoidal
PH: Prawns, crabs
Color Hyaline AH: Humans

PATHOPHYSIOLOGY OF ANGIOSTRONGYLUS
Angiostrongylus Cantonensis ADULT CANTONENSIS

Human eosinophilic meningitis - stiffness of the neck,

paresthesia, vomiting, nausea. Diplopia, fatigue, body or
muscle pain
●​ Chief complaint - acute/severe, intermittent occipital
or bitemporal headache

Treatment: No recommended treatment, but Albendazole and

Mebendazole demonstrated effective

GNATHOSTOMA SPINIGERUM
Causes: Visceral gnathostomiasis or larva migrans profundus

Parameter Male Female Has a wide range of paratenic host in the life cycle

Size 16-22 mm x 19-33 x 0.28-0.50 Tumor-forming

0.25-0.35 mm mm

Others Kidney-shaped, Uterine tubules Gnathostoma Spinigerum OVA

single lobed described as
caudal bursa “barber’s pole”
appearance

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 Parameter FERTILIZED EGG

Size 56-79 um x 35-43 um

Shape Elongated, ovoidal

Mucoidal plug on one end

Color Hyaline or brownish

Gnathostoma Spinigerum LARVA

Parameter

Size 2 mm to 2 cm

Others Contains cuticular spines on the

anterior and posterior part PATHOPHYSIOLOGY OF GNATHOSTOMA SPINIGERUM
●​ Cutaneous gnathostomiasis - most common
Cephalic bulb in the anterior part manifestation
●​ Visceral gnathostomiasis or larva migrans
profundus - fever. Malaise, nausea, and vomiting with
PH: Man, ducks, snake
development of peripheral eosinophilia
1st IH: Copepods
●​ Treatment: Surgical removal: albendazole or with
2nd IH: Fish, Frogs
ivermectin
Infective form in humans: AL3 in the tissue of the 2nd IH
MOT: contaminated water containing copepod

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 LESSON 4: BLOOD AND TISSUE NEMATODES
(MICROFILARIAE)

FILARIAL NEMATODES
●​ Blood Nematodes
○​ Lymphatic ●​ Common Name: Bancroft’s filaria
○​ Wuchereria bancrofti ●​ Causative Agent: Bancroft’s filariasis or elephantiasis
○​ Brugia malayi ●​ Size: 240 - 300 um
●​ Sheath is present
●​ Tissue Nematodes ●​ Nuclei is not present on the tip of the tail
○​ Subcutaneous ●​ Laboratory diagnosis: Giemsa stain, Knott Technique
○​ Loa loa ●​ Peak hours of blood collection: between 9pm to
○​ Onchocerca volvulus 4am; sometimes can be detected throughout the day
and more prevalent in the late afternoon
○​ Serous cavity and Subcutaneous ●​ Intermediate hosts: Culex, Aedes, Anopheles spp.
○​ Mansonella spp.
Clinical Symptoms:
GENERAL NOTES Asymptomatic
●​ Adult filariae produce larvae called microfilariae that 1.​ Eosinophilia
are usually detected in the blood 2.​ Enlarged lymph nodes, particularly in the inguinal
●​ Dimorphic area
●​ May exhibit periodicity 3.​ Self-limiting
●​ They are usually found in vectors
●​ Distribution: Asia, South and Central America, the Symptomatic
Caribbean 1.​ Fever and chills
2.​ Eosinophilia
LIFE CYCLE OF FILARIAL WORMS 3.​ Granulamotous lesions, lymphaginitis, and
lymphadenopathy
4.​ Lower elephantiasis
5.​ Calcification or formation of abscess

Treatment
1.​ Diethycarbamazine
2.​ Ivermectin (stromectol) + albendazole
3.​ Surgical removal of the microfilariae (rare case)
4.​ Unna’s paste boots
5.​ Elevation of infected area with bandages or simple
elevation

BLOOD NEMATODES
WUCHERERIA BANCROFTI

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 ●​ Often asymptomatic

Symptomatic
●​ Almost the same with bancroft filariasis but with
upper elephantiasis

Treatment
●​ The same with W. bancroft with DEC being the most
effective medication

BRUGIA MALAYI

●​ Common Name: Malayan filaria

●​ Causative Agent: Malayan filariasis or elephantiasis
●​ Size: 200 - 280 um
●​ Sheath is present with rounded anterior end
●​ Nuclei are numerous with 2 distinct nuclei separated MANIFESTATIONS OF LYMPHATIC FILARIASIS
from each other (ACCORDING TO BELIZARIO)
●​ Laboratory diagnosis: Giemsa stain, Knott Technique 1.​ Asymptomatic microfilaremia
●​ Peak hours of blood collection: nocturnal 2.​ Acute dematolymphagioadenitis
periodicity; sub periodic may appear (adenolymphangitis)*** (most acute)
●​ Intermediate hosts: Mansonia, Aedes, Anopheles spp. 3.​ Acute filarial lymphagitis*** (rare)
4.​ Lymphedema and elephantiasis** (most common)
5.​ Genitourinary lesions
Clinical Symptoms 6.​ Tropical pulmonary eosinophilia* (occult filariasis)

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

TISSUE NEMATODES
LOA LOA

ONCHOCERCA VOLVULUS

●​ Common Name: African Eye Worm

●​ Causative Agent: Loiasis
●​ Size: 248 - 300 um
●​ Sheath is present
●​ Nuclei are continuous to the tip of the pointed tail
●​ Laboratory diagnosis: Giemsa stain, Knott Technique
●​ Sample: Tissue
●​ Peak hours of blood collection: during midday,
between 10:15 am to 2:15 pm; diurnal periodicity
●​ Intermediate hosts: Chrysops fly

Clinical Symptoms
1.​ Development of Calabar swelling
2.​ Noticeable migration under the conjunctiva of the eye
or crossing under the skin of the bridge of the nose
3.​ Eosinophilia
●​ Common Name: Blinding filaria
●​ Causative Agent: River blindness, Onchocerciasis
Treatment
●​ Size: 150 to 355 um
1.​ Surgical removal
●​ Sheath is absent
2.​ DEC
●​ Nuclei are continuous but does not extend the tip of
the pointed tall
●​ Laboratory diagnosis: Giemsa stain
●​ Sample: Tissue biopsies, skin snips
●​ Peak hours of blood collection: random
●​ Intermediate hosts: Simulium black fly

Clinical Symptoms
1.​ Severe allergic reactions
2.​ Blindness
3.​ Loss of skin elasticity

Treatment
1.​ Ivermectin
2.​ Surgical removal

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 Symptomatic features
1.​ Urticaria
2.​ Lymphadenitis
3.​ Skin itching
4.​ Arthralgias

Treatment
1.​ Ivermectin

MANSONELLA OZZARDI

MANSONELLA PERSTAN

●​ Common Name: New World filaria

●​ Nonpathogen
●​ Size: ~220 um
●​ Sheath is absent
●​ Nuclei are continuous but does not extend the tip of
the rounded, blunt anterior tall
●​ Laboratory diagnosis: Giemsa stain
●​ Sample: Blood
●​ Peak hours of blood collection: No periodicity
●​ Intermediate hosts: Culicoides (sucking midge),
Simulium blackfly ●​ Common Name: Perstans filaria
●​ Nonpathogen
Clinical Symptoms ●​ Size: ~200 um
●​ Asymptomatic is common ●​ Sheath is absent

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 ●​ Nuclei are continuous filling the body and extends
to the tip of the rounded, blunt anterior tail
●​ Laboratory diagnosis: Giemsa stain
●​ Sample: Blood
●​ Peak hours of blood collection: No periodicity
●​ Intermediate hosts: Culicoides (sucking midge)

Clinical Symptoms
●​ Asymptomatic is common

Symptomatic features
1.​ Minor allergic reaction
2.​ Moderate eosinophilia
3.​ Calabar swellings
4.​ Arthralgia
5.​ Liver enlargement

Treatment
1.​ DEC
2.​ Mebendazole

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 Anapolytic
LESSON 5: PHYLUM PLATYHELMINTHES (CLASS ●​ Eggs are released through a uterine pore or by
CESTODES) rupture, but the segment stays attached or
disintegrates in situ
GENERAL CHARACTERISTICS
●​ Referred to as “flatworms” (tapeworms) ORDER OF CESTODA
●​ Flat, segmented, ribbon-like bodies
●​ Hermaphroditic (complete reproductive system male
and female)
●​ No circulatory system & No digestive system
●​ Bilateral symmetry
●​ Heteroxenous (they have two or more IH)

PARTS OF THE CESTODES

GENERAL LIFE CYCLE: PSEUDOPHYLLIDEA

1.​ Fertilized Egg

●​ The adult tapeworm in the definitive host
(human) produces fertilized eggs
●​ These are passed out through feces into the
environment (water)

2.​ Embryonated Egg in Water

●​ In water, the egg develops into an
embryonated egg that contains the first
larval stage

Larval Stages:
●​ L1: Coracidium
○​ A ciliated free-swimming larva called the
coracidium hatches from the egg
TWO KINDS OF GRAVID PROGLOTTIDS ○​ It must be ingested by the first intermediate
host (usually a copepod – a tiny aquatic
crustacean)

●​ L2: Procercoid
○​ Inside the copepod, the coracidium develops
into the procercoid larva
○​ This larva is infective to the second
intermediate host

●​ L3: Plerocercoid
Apolytic ○​ When the copepod is eaten by a fish (second
●​ Entire mature or gravid proglottids break off and pass intermediate host), the procercoid develops
out with the host's feces into the plerocercoid larva

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 ○​ The plerocercoid is the infective stage for
PROCERCOID
humans

Human Infection
●​ Humans (or other definitive hosts) get infected by
eating raw or undercooked fish containing the
plerocercoid
●​ Inside the human intestine, the larva develops into an
adult tapeworm, completing the cycle

DIPHYLLOBOTHRIUM LATUM
●​ Common name: Fish broad tapeworm, Broad
tapeworm, Russian Broad tapeworm
●​ Causative agent: of Diphyllobothariasis, Fish PLEROCERCOID
tapeworm infection, Fish tapeworm infection
●​ Size: 55-75 um long; 40-45 um wide
●​ Laboratory Diagnosis: Direct Fecal Examination
●​ Intermediate Hosts:
○​ 1st IH - Copepod
○​ 2nd IH - Fish - Human

MORPHOLOGICAL CHARACTERISTICS

Scolex

Appearance Distinguishing Features

Oval or ellipsoidal 1.​ Operculum - lid

No hexacanth structure at the
Consists of a ciliated larval anterior part
Stage called coracidium
2.​ Terminal Knob: aka
abopercular knob

LARVAL STAGES

CORACIDIUM

Appearance Distinguishing Features

Spatulate 2 sucking grooves

Almond-shaped (Midventral and middorsal
bothria)

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 PATHOGENESIS, CLINICAL MANIFESTATIONS, AND
TREATMENT
Clinical symptoms
1.​ Digestive disorders
2.​ Weakness
3.​ Megaloblastic anemia with thrombocytopenia and
leukopenia (Vitamin B12 deficiency)

Treatment: PRAZIQUANTEL

GENERAL LIFE CYCLE: CYCLOPHYLLIDEAN

Appearance Distinguishing Features

Rosette-shaped uterus Centrally located

reproductive system
​
ADULT FORM
1.​ Embryonated Egg (L1)
●​ Embryonated eggs are passed in the feces of
the definitive host (human)
●​ The eggs contaminate food, water, or the
environment

2.​ Intermediate Hosts

●​ Animals like pigs, cows, goats, sheep, or even
arthropods eat contaminated material
containing the eggs
●​ Inside these intermediate hosts, the eggs
hatch and release the oncosphere (L2)

●​ L2: Oncosphere
○​ The oncosphere is the larval form that has
hooks
○​ It penetrates the intestinal wall and migrates
via blood to tissues like muscle

●​ L3: Cysticercus
○​ In the tissues, the oncosphere develops into a
cysticercus — a fluid-filled cyst containing an
immature tapeworm

●​ Human Infection
○​ Humans get infected by eating raw or
undercooked meat containing the cysticercus
○​ Once inside the human intestine, the
cysticercus develops into an adult tapeworm,
completing the life cycle

●​ Key Hosts:
○​ Intermediate Hosts: Pig, cow, goat, sheep,
arthropods
○​ Definitive Host: Human

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 Taenia Solium Taenia Saginata Cysticercus bovis
T. saginata
Common name: Pork Common name: Beef
tapeworm tapeworm

Causative agent of Causative agent of

Taeniasis, Pork tapeworm Taeniasis, Beef tapeworm
infection infection, Cysticercosis

Laboratory Diagnosis: Laboratory Diagnosis:

Direct Fecal Examination, Direct Fecal Examination,
India ink India ink

Intermediate host: Pigs Intermediate host:

Cow/Cattles

SCOLEX

Appearance Distinguishing Features

Spherical or subspherical Embryophore

in shape Striated egg
Oncosphere
Hexacanth oncosphere 3 pairs of hooklets
T. solium

Rostellum Hooks
Cysticercus Cellulosae
T. Solium NO NO

NO ROSTELLUM AND HOOKS PRESENT

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 T. saginata Proglottid
T. saginata

Rostellum Hooks

YES YES

a.​ 300-400 follicular testes; with vaginal sphincter; 2

ovarian lobes
b.​ Central trunk with 15-20 lateral uterine branches
(dichotomous or tree-like)

Double row (double crown) of brown chitinous PATHOGENESIS, CLINICAL MANIFESTATIONS, AND
hooks arranged around the rostellum TREATMENT
Clinical symptoms
T. solium Proglottids 1.​ Digestive disorders and obstructions
2.​ Pruritis ani
3.​ Neurocysticercosis (T. solium)

Treatment: PRAZIQUANTEL; Surgical removal before

anti-parasitic drug for cysticercosis

Hymenolepis nana Hymenolepis diminuta

Common name: Dwarf Common name: Rat

tapeworm tapeworm

Causative agent of Causative agent of

Hymenolopiasis Dwarf Hymenolopiasis, Rat
tapeworm disease tapeworm disease

Laboratory Diagnosis: Laboratory Diagnosis:

Distinguishing feature Direct Fecal Examination Direct Fecal Examination
a.​ Mature segments
b.​ Gravid segments Intermediate host: Intermediate host:
Arthropod* Arthropod**
a.​ 100-200 follicular testes; 3 ovarian love (1 accessory)
b.​ Central trunk with 7-12 lateral uterine branches
(dendritic or fingerlike)

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

HYMENOLEPSIS NANA LIFE CYCLE a.​ PRESENT
b.​ PRESENT
c.​ PRESENT

HYMENOLEPSIS DIMINUTA EGG

Distinguishing Feature
HYMENOLEPSIS DIMINUTA LIFE CYCLE a.​ PRESENT
b.​ PRESENT
c.​ ABSENT

HYMENOLEPSIS NANA EGG

PATHOGENESIS, CLINICAL MANIFESTATIONS, AND

TREATMENT
Clinical Symptoms
1.​ Digestive disorders
2.​ Other clinical symptoms
Distinguishing Feature
a.​ Hooks* Treatment: PRAZIQUANTEL
b.​ Polar filament Alternative Treatment: Niclosamide
c.​ Polar knobs

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

DIPYLIDIUM CANINUM PROGLOTTIDS
Common Name: Dog Tapeworm, Cat Tapeworm, Pumpkin
seed Tapeworm
Causative Agent of Dipylidiasis, dog or cat tapeworm
Laboratory Diagnosis: Direct Fecal Examination
Intermediate Host: Arthropod* - Flea, Lonse

MORPHOLOGICAL CHARACTERISTICS

Appearance Distinguishing Features Distinguishing Feature

a.​ Mature segments
Sac-like containing 8-15 Has 6 hooks in its b.​ Gravid segments
eggs oncosphere

Thick-shelled capsule/sac a.​ 2 sets of male and female reproductive organs;

bilateral genital pores
Can be mistaken with b.​ Uterus not usually visible but sac like
Hookworm or Strongyloides
ova/egg PATHOGENESIS, CLINICAL MANIFESTATIONS, AND
TREATMENT
SCOLEX Clinical symptoms (usually in dogs or cats)
1.​ Digestive disorders
2.​ Other clinical symptoms
3.​ Anal pruritis

Treatment: PRAZIQUANTEL
Alternative Treatment: Niclosamide, Paromomycin

ECHINOCOCCUS GRANULOSUS
Common Name: Dog Tapeworm, hydatid tapeworm
Causative Agent of Echinococcosis, hydatid cyst. Hydatid
disease, hyatidosis
Laboratory Diagnosis: Biopsy, serologic test, radiography
Intermediate Host: Sheeps, Goat

MORPHOLOGICAL CHARACTERISTICS

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 PROGLOTTIDS
Appearance Distinguishing Features

With radial striations Identical and

With hooks indistinguishable to Taenia
spp.

LARVAL STAGE
Hydatid cyst

Appearance Distinguishing Features

Shortest tapeworm 3 proglottids:

1 immature
One set of reproductive 1 mature
organs 1 gravid

Midline uterus with lateral Resembles other taeniid

evaginations worms

ECHINOCOCCUS GRANULOSUS LIFE CYCLE

SCOLEX

PATHOGENESIS, CLINICAL MANIFESTATIONS, AND

TREATMENT
Clinical symptoms (usually in Human)
1.​ According to disease processes and symptoms

Treatment: SURGICAL RESECTION

Alternative treatment: Chemotherapy with benzimidazole
compounds

E. granulosus - cystic
E. multilocularis - alveoli (lungs)
E. vogeli & oligartus - polycystic

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

SONOGRAPHY SCOLEX

SPIROMETRA SPP. (also pseudophyllidean)

Common name:
Appearance Distinguishing Features
Causative agent of Sparganosis
Laboratory Diagnosis: Biopsy Thickened Resembles Diphyllobothrium
Intermediate Host: 1st IH - Copepods, 2nd IH - Amphibians, spp.
reptiles Wrinkled
Definitive Host: dogs and cats
Cleft-like or slit-like
invagination (anterior)
MORPHOLOGICAL CHARACTERISTICS

SPARGANUM

PROGLOTTIDS

Appearance Distinguishing Features

Asymmetrical shape Resembles egg of

Diphyllobothrium
Absent abopercular knob

Irregular pitting on the

surface

Indented operculum

Appearance Distinguishing Features

Spiral uterus pseudosegmentation

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

PATHOGENESIS, CLINICAL MANIFESTATIONS, AND
TREATMENT
Clinical symptoms (usually in dogs or cats)
1.​ According to disease processes and symptoms

Treatment: SURGICAL RESECTION

Alternative Treatment: Praziquantel

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 LESSON 6: TREMATODES

●​ Also known as Flukes

●​ Flat
●​ Bodies are non-segmented, dorsoventrally flattened,
and bilaterally symmetrical
●​ With a digestive tract, and two acetabula (suckers)
●​ Heteroxenous (contain two or more IH) - 1st host is
snail
●​ Never use human as intermediate hosts

CLASSIFICATION GENERAL LIFE CYCLE: TREMATODES

●​ According to reproduction (hermaphroditic)
○​ Monoecious - complete set of male and
female organs
○​ Dioecious - separate sexes

●​ According to habitat
○​ Lungs, Liver, Intestine, Blood

GENERAL PARTS OF FLUKES

1.​ Fertilized Egg

●​ Starts with the fertilized egg, which is usually
passed out from the definitive host (DH, often
humans or animals) through feces or other
means. It must have contact in water

2.​ Embryonated Egg

●​ The egg matures (embryonated) in the
environment, usually water

3.​ Miracidium
●​ The egg hatches into a free-swimming larva
called a miracidium
●​ The miracidium seeks out and penetrates the
first intermediate host (1st IH), typically a
snail.

4.​ Inside the 1st Intermediate Host (Snail):

●​ Sporocyst: Miracidium transforms into a
sporocyst, a sac-like stage
●​ Redia: From the sporocyst, redia develop,
another larval form
●​ Cercaria: The redia give rise to cercaria,
which are motile larvae (they often look like
tiny tadpoles)

5.​ Cercaria (outside the snail):

●​ The cercaria leave the snail and swim freely in
water
●​ They either directly infect the definitive host
or encyst on a second intermediate host

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 6.​ Metacercaria (on or in the 2nd Intermediate Host):
●​ Cercariae encyst to form metacercariae on or
in the second intermediate host (2nd IH)
●​ Examples of 2nd IH: fishes, plants,
crustaceans, snails

7.​ Definitive Host (DH):

●​ The definitive host (like humans or other
animals) eats the 2nd intermediate host
containing metacercariae
●​ Inside the definitive host, the metacercariae
encysted, mature into adults, and start the
cycle again by producing fertilized eggs

Morphological notes
●​ 1st Intermediate Host = Snail
●​ Broadly ovoidal
●​ 2nd Intermediate Host = Fish, plants, crustaceans,
●​ With opercular rim
etc.
●​ Flat operculum
●​ Definitive Host (DH) = Where the adult trematode
●​ Abopercular thickening
lives and reproduces (often humans or animals)

Paragonimus Westermani ADULT

MONOECIOUS FLUKES
●​ Lung Flukes
○​ Paragonimus westermani
●​ Intestinal Flukes
○​ Fasciolopsis buski, Echinostoma ilocanum
●​ Liver Flukes
○​ Fasciola hepatica, Clonorchis sinensis,
Opistorchis felineus
●​ Heterophyid Flukes
○​ Heterophyes heterophyes, Metagonimus
yokogawai

1.​ Leaf-like, non-segmented bodies, hermaphroditic

2.​ Eggs have distinct feature = operculated eggs
3.​ Has INFECTIVE STAGE = metacercaria
4.​ MOT: INGESTION of metacercaria
●​ Coffee-bean shaped
5.​ Host requirement: 3 host = 1st IH is always snail
●​ Zigzag intestinal ceca

PARAGONIMUS WESTERMANI
PATHOGENESIS, CLINICAL MANIFESTATIONS, AND
●​ Common Name: Oriental Lung Fluke
TREATMENT
●​ Causative Agent: of Paragonimiasis, Pulmonary
Clinical manifestations:
distomiasis
1.​ Sputum color in paragonimiasis: coffee-colored,
●​ Laboratory Diagnosis: Sputum examination,
blood-tinged colored, rusty-colored sputum
serological tests
(hemoptysis(
●​ Intermediate Hosts: 2nd IH - Freshwater crab,
2.​ Pulmonary discomfort (mimics tuberculosis)
crayfish
3.​ Fibrosis in lung tissue
4.​ Migrates to the brain
Paragonimus Westermani OVA

Treatment: PRAZIQUANTEL

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

 Fasciola Hepatica ADULT

●​ Distinct cephalic cone

●​ Marked widening at the base of the cone (shoulder)
●​ Branched intestinal structures

FASCIOLA HEPATICA
●​ Common Name: Sheep Liver Fluke, Temperate Liver
Fluke
●​ Causative Agent: of Fascioliasis, Sheep Liver Rot
●​ Laboratory Diagnosis: Stool examination, serological
tests
●​ Intermediate Hosts: 2nd IH - Water plants
(kangkong [ipomea obscura], watercress [Nasturtium
officinale])

Fasciola Hepatica OVA

PATHOGENESIS, CLINICAL MANIFESTATIONS, AND

TREATMENT
Clinical manifestations
1.​ Acute/Invasive stage: Diagnostic triad (Fever,
Hepatomegaly, Marked eosinophilia)
2.​ Chronic/Latent stage: Biliary obstruction
●​ Thin shell
3.​ Fibrosis in tissues
●​ Small operculum
4.​ Tongue Syndrome (Halzoun/Morara Syndrome)
●​ Irregular Abopercular end

Treatment: TRICLABENDAZOLE, BITHIONOL*

CLONORCHIS SINENSIS
●​ Common Name: Chinese Liver Fluke, Oriental Liver
Fluke
●​ Causative Agent: of Clonorchiasis
●​ Laboratory Diagnosis: Stool examination, serological
tests
●​ Intermediate Hosts: 2nd IH - Fish

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

OPISTHORCHIS FELINEUS ●​ Transverse vitellaria
●​ Common Name: Cat Liver Fluke
●​ Causative Agent: of Opisthorchiasis
●​ Laboratory Diagnosis: Stool examination, serological
tests
●​ Intermediate Hosts: 2nd IH - Fish
●​ Opisthorchis Viverrini (Southeast Asian Liver Fluke)

Clonorchis Sinensis OVA

●​ Thick, convex operculum, small abopercular knob PATHOGENESIS, CLINICAL MANIFESTATIONS, AND
TREATMENT
Opisthorchis Felineus OVA Clinical manifestations:
1.​ Cholangiocarcinoma
2.​ Hepatocellular carcinoma
3.​ 4 Histopathological phases
a.​ Desquamation of epithelial cells
b.​ Hyperplasia
c.​ Adenomatose tissue formation
d.​ Abortive acini & fibrosis

Treatment: PRAZIQUANTEL, ALBENDAZOLE, or COMBO

HETEROPHYES HETEROPHYES (Smallest Intestinal Fluke)

●​ Common Name: Dwarf Fluke, Heterophyid Fluke
●​ Ovoidal shape, tapering ends
●​ Causative Agent: of Heterophyiasis
●​ Laboratory Diagnosis: Stool examination
Clonorchis Sinensis ADULT
●​ Intermediate Hosts: 2nd IH - Fish

Heterophyes Heterophyes OVA

●​ Lancet shaped
●​ Dendritic testes
●​ Granular vitellaria

Opisthorchis Felineus ADULT

●​ Similar with C. sinensis but with smaller abopercular

knob
●​ Less distinct shoulder
●​ Thick shell

●​ Lobed testes

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

Heterophyes Heterophyes ADULT PATHOGENESIS, CLINICAL MANIFESTATIONS, AND
TREATMENT (for Heterophyiasis and Metagonimiasis)
Clinical manifestations:
1.​ Peptic Ulcer Disease or Acid Peptic Disease
2.​ Colicky abdominal pain
3.​ Mucoid diarrhea
4.​ Cardiac and neural tendencies (Heterophyes)

Treatment: PRAZIQUANTEL

FASCIOLOPSIS BUSKI
●​ Common Name: Giant Intestinal Fluke, Large
Intestinal Fluke
●​ Causative Agent: of Fasciolopsiasis
●​ Laboratory Diagnosis: DFS
●​ Genital sucker (3rd sucker) ●​ Intermediate Hosts: 2nd IH - Aquatic plants,
●​ With gonotyl chestnut, bamboo shots
●​ Skin covered with scale-like spines
Fasciolopsis Buski OVA
METAGONIMUS YOKOGAWAI
●​ Common Name: Heterophyid Fluke, Yokogawa’s
Fluke
●​ Causative Agent: of Metagonomiasis
●​ Laboratory Diagnosis: Stool examination
●​ Intermediate Hosts: 2nd IH - Fish

Metagonimus Yokogawai OVA

●​ Indistinguishable from F. hepatica and F. gigantica

ova

Fasciolopsis Buski ADULT

●​ Similar with C. sinensis but with smaller abopercular

knob
●​ Less distinct shoulder
●​ Thin shell but usually not distinguishable with H.
Heterophyes

Metagonimus Yokogawai ADULT

●​ No shoulders
●​ No cephalic cone
●​ Intestinal cecum not branched

●​ Larger than H. Heterophyes

●​ No gonotyl

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

PATHOGENESIS, CLINICAL MANIFESTATIONS, AND 4.​ MOT: INGESTION
TREATMENT 5.​ Host requirement: 2 host
Clinical manifestations:
1.​ Abdominal discomfort SCHISTOSOMA MANSONI
2.​ Intestinal obstruction ●​ Common Name: Manson’s Blood Fluke
●​ Causative Agent: of Intestinal Schistosomiasis
Treatment: PRAZIQUANTEL ●​ Laboratory Diagnosis: DFS, Liver and Rectal Biopsy
●​ Intermediate Hosts: Biomphalaria, Planorbis,
ECHINOSTOMA ILOCANUM Tropicorbis
●​ Common Name: Garrison’s Fluke ●​ Habitat: Mesenteric vein or RECTUM
●​ Causative Agent: of Echinostomiasis
●​ Laboratory Diagnosis: DFS SCHISTOSOMA HAEMATOBIUM
●​ Intermediate Hosts: 2nd IH - Snail ●​ Common Name: Vesical Blood Fluke
●​ Causative Agent: of Urinary Schistosomiasis
Echinostoma Ilocanum OVA ●​ Laboratory Diagnosis: Urinalysis
●​ Intermediate Hosts: Bulinus, Physopsis
●​ Habitat: Venous plexuses of URINARY BLADDER

SCHISTOSOMA JAPONICUM
●​ Common Name: Oriental Blood Fluke
●​ Causative Agent: of Oriental Schistosomiasis
●​ Laboratory Diagnosis: DFS, Liver and Rectal Biopsy,
MIFC
●​ Intermediate Hosts: Oncomelania quadrasi
●​ Habitat: Mesenteric vein of INTESTINE

Schistosoma Mansoni OVA

●​ Straw colored
●​ Can be mistaken as Fasciola and Fasciolopsis egg
although the latter two are bigger in size

Echinostoma Ilocanum ADULT

●​ Tapered, slightly curved

●​ Prominent lateral spine

ADULT

●​ Collar spines in its oral sucker

DIOECIOUS FLUKES
●​ Blood Flukes
○​ Schistosoma spp.

1.​ Cylindrical bodies, non-hermaphroditic, male has

distinct feature (gynecophoral canal)
2.​ Eggs have distinct feature (non operculated, terminal ●​ Coarsely tuberculated
spines) ●​ Anterior half, short
3.​ Has INFECTIVE STAGE (cercaria)

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA

Schistosoma Haematobium OVA ADULT

●​ Round
●​ Terminal spine

ADULT
●​ Smooth (non-tuberculated)
●​ Median, long

PATHOGENESIS, CLINICAL MANIFESTATIONS, AND

TREATMENT (Schistosomiasis)
Clinical manifestations
1.​ Hemozoin (brown, insoluble hemaxin pigment)
2.​ Cercarial dermatitis (Swimmer’s itch)
3.​ Fatigue, respiratory symptoms, arthralgias, myalgias,
malaise, eosinophilia, fever, and abdominal pain =
snail fever / Katayama fever
4.​ Hepatomegaly = oriental schistosomiasis
5.​ Granulomatous inflammatory reaction caused by egg
●​ Finely tuberculated
●​ Posterior half, long Treatment: PRAZIQUANTEL

Schistosoma Japonicum OVA

●​ Rounder
●​ Small lateral spine

Reyes, Sherichan C. Parasitology - Lecture BSMT - NU MOA