TEST 2 Intro to Parasitology

Question 1

Define Endoparasites

Answer 1

classified into intestinal, atrial or they may inhabit body tissues causing serious health problems.

Question 2

Define Ectoparasites

Answer 2

Arthropods that either cause diseases, or act as vectors transmitting other parasites.

Question 3

Define Definitive host (DH)

Answer 3

Harbours the adult or sexually mature stages of the parasite (or in whom sexual reproduction occurs).

Question 4

Define Intermediate Host (IH)

Answer 4

harbours larval or sexually immature stages of the parasite (or in whom asexual reproduction occurs)

Question 5

Define Reservoir host (RH)

Answer 5

Harbours the same species and same stages of the parasite as man. It maintains the life cycle of the parasite in nature and is therefore, a reservoir source of infection for man.

Question 6

Define Paratenic or Transport Host

Answer 6

Whom the parasite does not undergo any development but remains alive and infective to another host. Paratenic hosts bridge gap between the intermediate and definitive hosts.

Question 7

Define Vector

Answer 7

an arthropod that transmits parasites from one host to another, e.g. female sand fly transmits Leishmania parasites.

Question 8

Define peroral

Answer 8

Transmission by food or water contamination (e.g., roundworm, amoebae)

Question 9

Define Percutaneous

Answer 9

Skin Penetration

Question 10

Define Transmissive

Answer 10

Transmission by Insect vectors

Question 11

Define Transplacental

Answer 11

From Pregnant woman to fetus

Question 12

Define Sexual intercourse

Answer 12

Sexual transmitted

Question 13

Define airborn

Answer 13

Inhalation of contaminated dust or air ( pinworm)

Question 14

Define Helminthic parasites

Answer 14

• Multicellular organisms
• Parasitic worms such as flukes, tapeworms, and roundworms.
  
  • Trematodes (flat worms)
  • Cestodes (segmented ribbon worms)
  • Cylindrical worms (Nematodes)

Question 15

Define Protozoan parasites (unicellular organisms).

Answer 15

• Flagellates, amebas, ciliates, and sporozoa.

Question 16

What is the severe form of scabies?

Answer 16

Scabies Crustosa, aka Norwegian Scabies

Question 17

Define Monoxenous

Answer 17

direct - Having only one host in the life-cycle

Question 18

Define Heteroxenous

Answer 18

indirect - Parasites that have more than one host in their life cycles.

Question 19

How are parasites diagnosed?

Answer 19

• Imaging and Endoscopy, Clinical picture and geographic location.
• Direct microscopy of specimens (stool, urine, blood, CSF, and tissue).
• Antigen /Antibody detection assays

Question 20

Leishmaniasis basics

Answer 20

• Protozoan
• Spread by Sand flies (Phlebotomus)
• Two forms
  
  • Cutaneous leishmaniasis
  • Visceral leishmaniasis
• Exist in two vital stages:
  
  • promastigote: has flagella
    
    • Infective stage.
  • amastigote: no flagella

Question 21

Clinical Symptoms of Cutaneous leishmaniasis

Answer 21

• Low RBC count
• Skin sores within weeks or months of bite.
  
  • Red papule (1st symptom) appears within 2 weeks-2 months of bite.
• Untreated may develop into the mucocutaneous form in up to 80% of cases.
  
  • Spread to the nasal and oral mucosa may become apparent concomitant with the primary lesion or years after it has healed.

Question 22

Clinical Symptoms of Visceral leishmaniasis

Answer 22

• Incubation period: Several weeks to a year
• Can be rapidly fatal, slow and debilitating or asymptomatic.
• Aka, Kala-azar (“black fever” in Hindi), dumdum fever.
• Caused by
  
  • L. donovani
  • L. infantum

Question 23

Diagnosis of Leishmaniasis:

Answer 23

• Detection of either the amastigotes in clinical specimens or promastigotes in culture.
• VL:
  
  • Splenic puncture
  • Lymph node aspirates
  • Liver biopsy
  • sternal aspirates
  • Iliac crest bone marrow
• Detection of leishmanial DNA or RNA

Question 24

Define Trypanosomiasis:

Answer 24

Diseases in vertebrates caused by parasitic protozoan trypanosomes of the genus Trypanosoma.

Question 25

Common name of American trypanosomiasis?

Answer 25

**Chagas disease**

Question 26

What is the causative organism of Chagas disease

Answer 26

Trypanosoma cruzi

Question 27

Chagas Disease transmission

Answer 27

* Bite from infected triatomine bug ("Kissing bug") * **Blood transfusions and organ transplants** * Second most common mechanism of transmission. * **Transmission through birth** * Less frequent.

Question 28

**Clinical symptoms** of **Chagas?**

Answer 28

* **Romana's Sign:** Unilateral swelling of the eyelids. * **Acute stage**: local skin nodule “chagoma” * Usually asymptomatic * **Indeterminate Stage:** * 8-10 weeks no symptoms. * **Chronic Stage:** * Dementia, Cardiomyopathy, altered heart rate or rhythm, sometimes dilation of the digestive tract, weight loss.

Question 29

**Diagnosis** of **Chagas**

Answer 29

* “Buffy coat” after centrifugation of heparinized blood. * T. rangeli looks very similar to T. cruzi in smears. * “Xeno-diagnosis” allowing uninfected, lab-bred kissing bugs to feed on patient and later examining the contents of the bug for the parasite. * Serologic Tests: * indirect hemagglutination or immunofluorescence * ELISA test

Question 30

Treatment of **Chagas**

Answer 30

* No effective treatment * Benznidazole and Nifurtinox: current drugs of choice to kill extracellular parasites. * Hospital may be needed to treat symptoms

Question 31

**Prevention** of **Chagas**

Answer 31

* Avoid sleeping in poorly constructed thatch, mud housing * Use insecticides * Be aware of the risk of contracting Chagas disease through blood transfusion.

Question 32

What is the common name of Schistosomiasis?

Answer 32

Bilharzia

Question 33

What are the three causative species of Schistosomiasis?

Answer 33

S. mansoni, S. haematobium, and S. japonicum

Question 34

Pathology of Schistosomiasis?

Answer 34

* Migration phase (from penetration to egg production) * Toxic reactions and pulmonary congestion; fever. * Lasts 4-10 weeks * Move from lungs to final tissue. * Acute Phase (begins at egg production) * 2 months - several years. * Chronic Phase: * Chronic bloody diarrhea, with mild abdominal pain and lethargy. * Hepatomegaly * **Granuloma** forms around eggs that become trapped in the walls of the intestine and urinary bladder.

Question 35

**Treatment** of **Schistosomiasis?**

Answer 35

* No reliable prophylactic regimen is available, other than the observance of proper sanitation. * Avoidance of cercariae-infested waters, and prevention of water contamination by human excreta.