CLINICAL AND IMAGING DIAGNOSIS OF PARASITIC DISEASES

1. Diagnosis of
Parasitic Diseases
• Clinical
Approaches
• Imaging
Techniques
Dr. Ibrahim Aboulasaad
Subsidiary
Parasitology

2. Overview
The diagnosis of parasitic diseases is a complex process that requires a multidisciplinary
approach involving clinical, laboratory, and sometimes imaging techniques.
• Clinical evaluation is the first step in diagnosing parasitic diseases, wherein healthcare
professionals assess the patient's medical history, symptoms, and physical examination
findings. Some parasitic infections can present with characteristic clinical signs, but many
are nonspecific, making it necessary to perform specific tests for confirmation.
• Imaging modalities, such as X-rays, ultrasound, computed tomography (CT), and
magnetic resonance imaging (MRI), are occasionally used to detect parasitic infections
in organs and tissues that are difficult to access or visualize directly.
• Laboratory methods play a pivotal role in diagnosing parasitic diseases. Microscopic
examination of various body fluids, such as blood, stool, urine, and tissue samples, is a
common and essential technique. Additionally, serological tests that detect antibodies
or antigenic components produced during the infection can aid in diagnosing some
parasitic diseases. Recently, Polymerase chain reaction (PCR) assays allow for precise
detection and differentiation of parasitic species and strains, particularly in cases where
traditional methods might be less sensitive or specific.

3. Clinical
Diagnosis
Significant of clinical approaches for
diagnosis of parasite infections:
• It is not specific diagnostic tool, but it is the
primary step for diagnosis.
• It may be efficient diagnostic way in some
parasitic infections
• It helps to choose the most confirmative
diagnostic procedures.
• It help to assess the morbidity of parasitic
infection.
• It is a valuable index for assessment of
treatment and follow up.

4. • The clinical diagnosis of parasitic diseases involves the identification and evaluation
of signs and symptoms presented by the patient, which may indicate the presence of a
parasitic infection. It is the initial step in the diagnostic process and serves as the basis
for further investigation using laboratory tests and imaging studies. The aspects of
clinical diagnosis for parasitic diseases include;
Aspects of clinical diagnosis for parasitic diseases.
1. Medical History: The patient's medical history is crucial in guiding the diagnostic
process. The healthcare professional will inquire about the patient's symptoms,
their onset, duration, and any factors that may have triggered or exacerbated
them. Specific questions related to occupation of the patient , dietary habits,
residence in endemic areas, exposure to potential sources of infection, and
recent contact with infected individuals or animals. Medical history is essential
for narrowing down the possibilities of parasitic diseases.
2. Endemic Area and Travel History: Geographic location plays a significant role in
determining the likelihood of specific parasitic infections. Some parasites are
prevalent in specific regions or countries, and knowledge of the patient's travel
history can help direct the diagnostic investigation. For instance, malaria is
common in tropical and subtropical regions, while Chagas disease is prevalent in
parts of Latin America.

5. 3. Symptoms: Parasitic infections can manifest in various ways, depending on the type
of parasite and the organ systems involved. Common symptoms include fever,
fatigue, weight loss, gastrointestinal disturbances (such as diarrhea, abdominal pain,
and nausea), skin rashes, itching, and respiratory problems. Some parasitic
infections may have specific symptoms, Examples include the acute febrile illness
with headache and muscle pain observed in acute malaria.
4. Physical Examination: A thorough physical examination can provide valuable clues
to the presence of a parasitic infection. The healthcare provider will look for specific
signs like enlarged lymph nodes, organomegaly (enlarged organs), skin lesions, and
other physical manifestations. Combination of symptoms and signs may lead to the
identification of a specific clinical syndrome associated with parasitic infections,
such as the enlarged liver and spleen seen in visceral leishmaniasis.
5. Differential Diagnosis: Many parasitic infections share symptoms with other
infectious and non-infectious diseases. The process of differential diagnosis involves
ruling out other potential causes of the patient's symptoms.
It is important to note that clinical diagnosis alone is often insufficient to confirm the
presence of a parasitic disease definitively. Laboratory tests, imaging techniques, and
endoscopy in soma cases may be typically required for confirmation and identification of
the specific parasite.

6. Clinical manifestations of Parasitic Diseases
• The clinical manifestations of parasitic diseases are variable and
involve any body site. These manifestations include:
• General manifestations
• Abdominal manifestations
• Chest manifestations
• Genito-urinary manifestations
• Neurological manifestations
• Lymphatic manifestations.
• Dermatologic manifestations.
• Ocular manifestations.

7. General manifestations of parasitic diseases
• Fever.
• Anemia.
• Jaundice.
• Chronic Fatigue: Parasites can draining the body of both nutrients and energy.
• Retardation of mental and physical development.
• Psychological troubles:
o Teeth Grinding: This symptom of parasite infection occurs most often at
night, and it may be linked to the restlessness and anxiety caused by the
parasite’s release of waste and other toxins.
o Sleep Disorders: Intestinal parasites can cause irritation that can disturb
sleep patterns e.g., Enterobius & Scabies.
Fever in parasitic diseases:
• Fever is a common symptom associated with various parasitic diseases. When the
body's immune system responds to a parasitic infection, it often triggers an
inflammatory response, leading to the release of pyrogens (fever-inducing substances).
• Fever is the body's natural defense mechanism that helps fight off the invading
parasites by creating an unfavorable environment for their growth and replication.
Parasitic infections may cause short temporary fever or, prolonged recurrent fever

8. Parasitic diseases associated with Prolonged recurrent fever
Parasitic infections are listed as a cause of “Fever of Unknown Origin”
Prolonged recurrent fever can be a prominent feature in certain parasitic diseases. These
infections often induce cyclical fever patterns due to the life cycles of the parasites or the
host's immune response to ongoing infections.
• Malaria: The classic symptom of malaria is a cyclical fever, where the patient experiences
fever spikes and chills in regular intervals, depending on the species of Plasmodium
involved.
• Visceral Leishmaniasis (Kala-azar): The fever may be irregular but persists for extended
periods, and other symptoms include weight loss, enlarged spleen and liver, and anemia.
• African Trypanosomiasis (Sleeping Sickness): Recurrent fever spikes, along with other
symptoms such as headaches, joint pain, and neurological changes.
• Microsporidiosis: Microsporidiosis is caused by various microsporidian parasites, and it can
affect different organs, leading to recurrent fever along with gastrointestinal, respiratory, or
systemic symptoms.
• Toxoplasmosis: especially in immunocompromised individuals or during the acute phase of
the infection.

9. • Chagas Disease: In the acute phase of the disease, fever can be a prominent
symptom.
• Lymphatic Filariasis: It can lead to recurrent fever, along with other symptoms
such as lymphedema (swelling of limbs), hydrocele (fluid accumulation in the
scrotum), and elephantiasis.
• Schistosomiasis: In the acute stage of infection, fever may be present, along
with other symptoms such as cough and muscle aches.
• Cysticercosis: it can occur in cases with widespread dissemination of cysts or
when cysts affect the brain or other vital organs.
• Strongyloidiasis: In chronic infections, it can lead to recurrent fever,
abdominal pain, and diarrhea.
• Amoebic liver abscess: : It can cause prolonged fever, hepatomegaly and liver
tenderness.
• Fascioliasis: It can cause prolonged fever, liver tenderness, and other
gastrointestinal symptoms.
Parasitic diseases associated with Prolonged recurrent fever

10. Anaemia in parasitic diseases:
Anaemia is a characteristic sing in many parasitic diseases;
 Enumerate these parasites?
 Define the characters of anaemia in parasitic diseases?
1) Hypochromic-microcytic, as; ……………
2) Pernicious or megaloblastic, as; ……………
3) Haemolytic, as; ……………
4) Aplastic, as; ……………
Retardation of mental and physical development.
Defend the causative factors of mental and physical retardation in
parasitic infections?
a) Nutritional deficiency and chronic anemia, as ……………………
b) Congenital infection (maternal-fetal transmission), as Toxoplasma
gondii, Trypanosoma cruzi and Plasmodium sp.

11. Parasitic causes of
Jaundice
• Jaundice is yellowish discoloration of the
skin and mucous membranes caused by
hyperbilirubinemia.
TYPE PARASITIC CAUSE
Pre-hepatic
Hemolytic jaundice
1) Plasmodium spp.
2) Babesia spp.
Hepatic
Hepatocellular jaundice
1) Schistosomiasis, (acute and late stage).
2) Fascioliasis, (acute stage).
3) VLM.
4) Kala-azar, (late stage).
5) Congenital toxoplasmosis.
6) Malaria.
7) amoebic hepatitis.
Post-hepatic
obstructive jaundice.
1) Fasciola spp. (chronic stage)
2) Hydatid cyst
3) Wandering Ascaris lumbricoides
4) Clonorchis sinensis

12. Abdominal
manifestations of
parasitic diseases
• Intestinal Manifestations
• Extra-Intestinal Manifestations
Parasites causing Intestinal Manifestations are:
a) Intestinal parasites in most cases
b) Tissue parasites as, Schistosomiasis and as complications
in Malaria & Visceral leishmaniasis
Intestinal Manifestations include:
a) The common tirade: Colic + Vomiting + Abnormal bowel
habits.
b) Uncommon manifestations as, Colonic masses and
intestinal obstruction.
Intestinal Manifestations
Vomiting:
a) Vomiting + diarrhea + Fever (the triade of acute
gastroenteritis), Characterize acute intestinal parasitic
infections, as ………
b) Sever projectile vomiting occurs in cerebral infections with
 intracranial pressure, as …………..
c) Sever vomiting contaminated with fecal matter occurs due
to intestinal obstruction complicating parasitic infections,
as, …………
d) Hematemesis in case of, ……….

13. Steatorrhea
Steatorrhea is the presence of excess fat in feces. Stools have an oily appearance, gray or pale
and foul-smelling. Parasitic causes of Steatorrhea are: Parasites causing extensive
Inflammation of the intestinal mucosa: Giardia, Cryptosporidium, and Intestinal Capillaria.
Parasites causing biliary obstruction: Fasciola, Wandering Ascaris and Hydatid cyst
Colonic masses
Abdominal masses related to colon may be:
o Schistosoma colonic polyposis: common site in the left iliac fossa.
o Ameboma: common site in the right iliac fossa.
Diarrhea
• Diarrhea is a frequent, loose, watery stools as a result of inflammation of the small
intestine mucosa.
• Some parasites may cause acute sever diarrhea + dehydration, as: Capillarasis and
Cryptospordiasis.
• Some parasites may cause chronic diarrhea + mal-absorption, as: Giardiasis, Capillarasis
and Cryptosporidiosis.
Dysentery
• Dysentery is an inflammation of the large intestine causing diarrhea with blood
and mucus. Parasites causing dysentery are: ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

14. Parasitic causes
of acute
abdomen
An acute abdomen refers to a sudden and severe onset of abdominal pain,
often requiring immediate medical attention and diagnosis. Some parasitic
infections can lead acute abdomen:
• Appendicitis: due to Enterobius vermicularis, Trichuris trichiura, or
migrating Ascaris
• Intestinal Obstruction complicating Ascariasis, Strongyloidiasis, or
Taeniasis.
• Biliary Obstruction: Liver fluke infections or migrating Ascaris.
• Peritonitis: Parasitic infections, such as Entamoeba histolytica causing
amoebic colitis, can lead to inflammation and ulceration of the
intestinal wall. If these ulcers rupture, they can cause peritonitis,
Ascaris worms can also perforate the intestine causing peritonitis,
Ruptured intraabdominal hydatid cyst cause severe peritonitis and
anaphylaxis..
• Acute Pancreatitis: Infections with certain parasites, such as Clonorchis
sinensis and Ascaris lumbricoides, have been associated with acute
pancreatitis, which can lead to acute abdominal pain.
• Ectopic Migration: Some parasites, like Ascaris lumbricoides,
Strongyloides stercoralis, Paragonimus, and Fasciola can undergo
ectopic migration, where they migrate to other organs outside of the
gastrointestinal tract. This migration can cause localized inflammation
and severe abdominal pain.

15. Abdominal
Extra-Intestinal
Manifestations
Causes:
o Parasitic infections of the liver & spleen.
o Parasitic infections of the kidney.
o Parasitic infections of the abdominal cavity.
Hepatosplenomegaly
o Patient complains heaviness or pain in upper
abdomen.
o Examination may reveal:
• Enlarged tender lever and/or spleen.
• Umbilical eversion down.
Enumerate Parasites causing Hepatosplenomegaly?
Parasitic infections of the kidney:
a) Hydatid cyst.
b) Hydronephrosis and pyelonephritis complicating S.
haematobium.
o Patient may complain loin heaviness or pain.
o Examination may reveal full, dull and tender renal
angle.

16. Parasitic infections of the abdominal cavity:
a) Hydatid cyst  Hydatid Thrill.
b) Abdominal paragonimiasis  painful & tender like abscess.
c) Body cavity filariasis; often asymptomatic.
Abdominal hydatid cyst:
 Abdomen was tense with engorgement of veins
over the lateral sides.
 The lump was huge, cystic in consistency with
well defined margins.
 Fluid thrill present, but shifting dullness was
absent.

17. Chest
manifestations of
Parasitic Diseases
Parasitic infections with thoracic
involvement, including:
o Protozoa: (Amoebiasis, Malaria, Trypanosomiasis &
Toxoplasmosis).
o Nematodes:
• Loeffler’s syndrome: Pulmonary manifestations
produced by migrating nematode larvae of, ………...
• Tropical Pulmonary Eosinophilia: Associated with
Filarial Parasites
o Trematodes: (Schistosomiasis & Paragonimiasis).
o Cestodes: (Hydatid disease & Cysticercosis).
o Arthropods: (House Dust Mites causing Bronchial
asthma)
Chest manifestations includes:
1) Cough.
2) Expectoration.
3) Dyspnea.
4) Wheezes.
5) Chest pain.

18. Parasitic infections of the heart
(Cardiac Parasitism)

19. Genito-urinary
manifestations of
Parasitic Diseases
Common Genito-urinary Parasites
1) S. haematobium.
2) T. vaginalis.
3) W. Bancrofti.
Other parasites may infect Genito-urinary system:
1. S. mansoni eggs (5%)
2. Hydatid sand: ruptured renal Hydatid cyst.
3. Enterobius in females.
4. O. volvulus.
5. Urinary myiasis.
6. Sarcoptes.
7. Phthirus pubies.
Manifestations includes:
 Dysuria & frequency.
 Abnormal colours of urine.
 Urethral Discharges.
 Vaginal Discharges.
 Renal colic.

20. Parasites causing dysuria:
• S. haematobium: Usually accompanied with hematuria.
• E. vermicularis: When the adults migrate to the urethra in female patients.
• T. vaginales: Extension of inflammation to the urethra in both male & female,
and the prostate in male patients.
• Urinary myiasis.
Abnormal colours of Urine:
1) Brownish or greenish; (Bilirubin); in parasites causing jaundice.
2) Reddish & turbid; (haematuria); in S. haematobium infection.
3) Milky (Chyluria); in lymphatic filariasis.
4) Dark red or black urine; (haemoglobinurea); in black water fever in P.
falciparum infection.
Parasites causing renal failure:
 Chronic infection with Schistosoma haematobium
 Malaria: In severe cases of malaria, the parasites can adhere to and obstruct small blood
vessels in the kidneys
 African trypanosomiasis (Sleeping Sickness) can lead to kidney damage as the parasites
invade various organs, including the kidneys.
 Filariasis: In some instances, lymphatic filariasis can lead to renal lymphatic obstruction and
kidney damage.

21. Neurological
manifestations
Parasitic infections of CNS include:
I. Protozoa: Amoebiasis( E. histolytica & Free living
amoeba), Toxoplasmosis, Malaria and
Trypanosomiasis.
II. Nematodes: Toxacariasis, Strongyloidiasis and
Trichinosis.
III. Cestodes: Echinococcosis, Cysticercosis, Coenurosis,
and Sparganosis.
IV. Trematodes: Schistosomiasis, Paragonimiasis.
The clinical manifestations are often nonspecific and depend
on the type and location of the lesions;
1) Manifestations of meningo-encephalitis:  Fever,
vomiting, headache, and seizure.
2) Manifestations of space occupying lesions:
a) Increased intracranial pressure as headache, vomiting
& seizure.
b) Focal neurologic deficit as seizure, sensory or motor
disturbances.

22. Lymphatic manifestations
Lymphadenopathy &
Lymphatic oedema
• Localized lymphadenopathy as:
• Lymphatic Filariasis.
• Cutaneous leishmaniasis in
regional lymph nodes.
• Generalized lymphadenopathy as:
• Toxoplasmosis.
• Visceral leishmaniasis.
• Trypanosomiasis.
• Lymphatic oedema:
• Lymphatic Filariasis.

23. Dermatologic
Manifestations
of Parasitic
Infections.
A wide range of parasitic infections can involve the skin
and subcutaneous tissues producing the following
Manifestation;
• Itching
• Erythema
• Urticarial rashes
• Localized cutaneous swelling
• Nodules
• pustules
• Ulcers
• Depigmentation
Itching:
1. Swimmer’s itching (cercarial dermatitis), caused by Schistosoma cercariae.
2. Ground itching caused by Nematode infective larvae (L3).
3. Perianal itching caused by female Enterobius vermicularis
4. Pruritus caused by microfilariae of Onchocerca
5. Larva currens: In external autoinfection with S. stercoralis severe itching, over the
thigh and trunk.
6. Nocturnal itching, caused by Sarcoptes scabiei.

24. Erythema:
Redness of the skin, caused by hyperemia of
superficial capillaries. Ex: CLM .
Urticarial rashes
o It is frequently caused by allergic reactions
concomitant with eosinophilia or increased IgE.
o It is frequently affect wide area of skin. e.g.:
• During acute phase of infection with tissue parasite
as Fasciola, Schistosoma, Trichinella.
• Occult Filariasis.
• Allergic reaction to HDM.
Localized Inflamed Cutaneous Swelling.
 Calabar swellings (Angioedema):  Loa loa.
 Chancre:  Trypanosoma.
 Chagoma: Chagas disease.
 Acne: demodex mites.

25. Localized Inflamed Cutaneous Swelling

26. Nodules:
Solid, raised areas in or under the skin that are larger than 0.5 centimeters.
1) Onchocerciasis: Subcutaneous nodules
2) Cutaneous sparganosis: migrate and accompanied by painful edema.
3) Cysticercosis: Subcutaneous cysts mainly on the trunk and extremities.
4) Post kala-azar dermal leishmaniasis: appear few years after treatment.
Ulcers:
1) Cutaneous leishmaniasis.
2) Mucocutaneous leishmaniasis.
3) Tungiasis: caused by female Tunga penetrans.
4) Amoebiasis
5) Dracontiasis
6) Acanthamoeba infection.
7) Cutaneous Myiasis: Skin infection by larvae of Dermatobia fly.
Pustules:
Skin pustules are small, pus-filled bumps on the skin. These pustules are often a result of the
body's immune response to the presence of parasites or their larvae in the skin. Parasitic
infections associated with skin pustules:
• Scabies
• Cutaneous Larva Migrans
• Cutaneous Leishmaniasis
• Furuncular Myiasis

27. Nodules

28. Pustules

29. Ulcers

30. Ocular
Manifestations
of Parasitic
Diseases
• Parasitic infections of the eye include:
• Toxoplasmosis  chorioretinitis
• Chagas' disease periorbital edema
(Romana's sign),
• Leishmaniasis:
• Acanthamoeba infection:
acanthamoebic keratitis.
• Malaria: retinal hemorrhage
• Onchocerciasis: punctate keratitis &
optic atrophy  Blindness.
• Loiasis: conjunctival congestion.
• Cysticercosis
• Toxocariasis.
• Echinococcosis.
• Myiasis.
• Lice (Pediculus andPhthirus).

31. Imaging Techniques
for Diagnosis of
Parasitic Diseases
Significances of imaging techniques in
parasitic diseases:
1) Diagnosis of parasitic infections.
2) Assessment of pathology and
complications.
3) Assessment of cure after
treatment and follow up.
Imaging techniques include:
o Radiography
• X-rays.
• Computed tomography (CT).
o Magnetic resonance imaging (MRI).
o Ultrasonic imaging (US).

32. X-rays
• X-ray can be carried out quickly and easily.
• But the hazard of radiation exposure limits its use in
some cases as pregnancy.
• It provides benefit images in cases of;
o Suitable contrast media as air or bone, as Hydatid
cyst, Amoebic abscess, and B. westermani
o Calcified parasite in soft tissues as Dracunculus
medinensis and, hydatid cyst, and cysticercosis.
Chest radiography showing:
(A) Well-defined single
rounded opacity in the left
lung of a patient with
unruptured hydatid cyst.
(B) Well-defined left and
right rounded opacities in
both lungs of a patient with
unruptured hydatid cysts.

33. • Chest radiography shows
ruptured hydatid cyst
• chest X-ray showed right lung abscess
(Pulmonary Amoebiasis). The abscess has
ruptured into a bronchus with partial
expectoration of its contents. There is a
large air-filled cavity with a fluid level.
• Chronic Pulmonary Schistosomiasis. “Bilharzial” cor
pulmonale. Chest X-ray showing signs of pulmonary
hypertension (prominent fourth arc – arrow).

34. Patient with multiple “rice-grain”
calcifications in thigh muscles due
to disseminated cysticercosis.
Plain radiograph showing
Convoluted, serpiginous calcification
in a necrotic adult guinea worm in
the soft tissues of thighs and calf
Hydatid disease of the distal femur.

35. Plain x-ray abdomen showing large calcified
unilocular hydatid cyst in the liver..
Plain X ray film:
showing multiple air fluid levels (blue arrow heads)
and cigar bundle appearance in ileo-cecal area
caused by Ascaris worm bolus (red arrow).

36. Ultrasonography
Ultrasound-based
diagnostic imaging
technique used for
visualizing internal body
structures including
tendons, muscles, joints,
vessels and internal
organs.
Advantages:
1)It allows easy and proper adjustment of the view.
2)Can provides proper imaging without the need for contrast.
3)It is portable and can be brought to a sick patient's bedside.
4)It is substantially lower in cost.
5)It is safe as it does not use harmful ionizing radiation.
Disadvantages:
1) Difficult imaging structures behind bone, as brain.
2) its relative dependence on a skilled operator.
Uses of Ultrasound in parasitic diseases:
1.Diagnosis of parasitic infections, e.g., Schistosomiasis,
Abdominal Hydatid disease, Lymphatic filariasis (Filarial dance
sign), and Amoebic liver abscess
2.Assessment of pathology and complications of parasitic
infections as in schistosomiasis, fasioliais and migrating ascaris.
3.Detection of fetal anomalies due to congenital parasitic
infections as, Toxoplasmosis.
4.Guide needle biopsy and aspirate in some parasitic diseases as in
liver, lymph nodes, congenital toxoplasmosis, …..

39. Lymphatic filariasis (Filarial dance sign)

40. Computed Tomography (CT)
• Computed tomography (CT) uses special x-ray
equipment to make cross-sectional pictures of
the body.
• This technique provides tomographic images or
slices of specific areas of the body from a large
series of two-dimensional X-ray images taken in
different directions.
• The two-dimensional (2D) imaging provides more
clear images, but some exams require a special
dye (contrast) to helps the radiologist see certain
areas more clearly.
• Intravenous contrast agents are used to enhance
organs and visualize blood vessels. Oral contrast
agents are used to visualize the digestive tract.
• CT scan have the hazard of radiation exposure as
X ray.
Uses of CT in parasitic diseases:
1) Can be used following Ultrasound imaging for more clear images.
2) Imaging structures behind bone as CT scan of the brain and spinal cord.

42. Magnetic
Resonance
Imaging (MRI)
• A procedure that uses radio
waves, a powerful magnet, and a
computer to make a series of
detailed pictures of areas inside the
body. A contrast agent may be
injected into a vein to help the
tissues and organs show up more
clearly in the picture. It is especially
useful for imaging the brain and
spinal cord, the organs in the pelvis
and abdomen, and the breast.
• MRI is in general more safe
technique in comparison CT, since
MRI does not use any ionizing
radiation. MRI is highly technical,
needs especial equipment and spend
longer time in comparison CT.

44. D. Ibrahim