Parasitology Written Book

Question 1

Give reason Katayama syndrome (Acute toxaemic schstosomiasis) is most commonly seen with Schistosoma japonicum infections (pg 137)

Answer 1

Due to the large number of eggs laid per female and greater proximity to the liver.

Question 2

Give reason Ascaris lumbricoides (Loeffler syndrome) can cause life-threatening complications (pg 39)

Answer 2

Migrating larvae trapped in the liver or reaching the systemic circulation may induce granuloma formation in several organs.

Question 3

Give reason Antiemetics are given during the treatment of infections with T. solium (pg 29)

Answer 3

Because vomiting should be avoided, as retrograde peristalsis may allow gravid proglottids to be digested with egg hatching, penetration of larvae and development of cysticercosis.

Question 4

Give reason Playing with dogs does not lead to having visceral larva migrans (pg 108)

Answer 4

Because eggs of Toxocara with stool of dogs are immature not infective & need about 2-3 weeks

Question 5

Give reason Development of cor pulmonale in shcistosomiasis (pg 132)

Answer 5

soma eggs lead to pulmonary arteriolitis Pulmonary hypertension and right sided heart failure

Question 6

Give reason Severe hypochromic microcytic anaemia is usually reported in ancylostomiasis (pg 46)

Answer 6

Due to chronic blood loss and depletion of iron stores. Blood loss is caused by the worm attached to the intestinal mucosa by its buccal capsule

Question 7

Give reason Fluid and electrolyte replacement with high-protein diet are important for proper treatment of intestinal capillariasis (pg 59)

Answer 7

Severe protein losing enteropathy may occur with intestinal capillariasis as parasitic invasion of the intestinal mucosa, leads to enteropathy, with chronic inflammatory reactions and atrophy of villi. This consequently affects intestinal functions and leads to malabsorption of fats, proteins, electrolytes and sugars.

Question 8

Give reason Repeated stool analysis may be needed in suspected causes of fascioliasis (pg 102)

Answer 8

Stool analysis is negative in the prepatent period (eggs are excreted after 3-4 months). Eggs are not detectable in chronic cases due to fibrosis

Question 9

Give reason Heterophyes infection may lead to CNS manifestations (pg 6)

Answer 9

Due to egg embolism caused by eggs outside intestine leading to brain granulomas &
neurological deficits

Question 10

Give reason Human excreta should be properly treated before being used as a fertilizer (pg 48, 53)

Answer 10

Human excreta should be properly treated before being used as a fertilizer disinfection of human excreta should be done to prevent parasitic infections as ancylostomiasis

Question 11

Give reasons it is important to give treatment if primary T. gondii infection is confirmed during pregnancy (pg 213)

Answer 11

If primary T. gondii infection is confirmed, drugs are given to the pregnant for the prophylaxis against foetal infection

Question 12

Give reason relapse is not seen in malignant malaria (pg 174)

Answer 12

Because there are no liver hypnozoites to be activated causing relapse

Question 13

Give reason babesia may be considered an opportunistic parasite (pg 179)

Answer 13

Because Babesia causes severe disease that may require hospitalization in cases of splenectomy, HIV infection or with immunosuppressive
drugs.

Question 14

Give reason lymphangitis and its sequelae in lymphatic flariasis are multifactorial (pg 153)

Answer 14

Lymphangitis and its sequelae are due to blockage of lymph nodes and
vessels:

• Mechanically by the adult worms.
• Due to body’s immune response to worms (developing, adult, dying).
• Due to bacterial or fungal infection.

Question 15

Give reason East African trypanosomiasis is more dangerous than the West African type 197

Answer 15

Because in East African type, the course of disease is rapid and acute,
CNS involvement is earlier and myocarditis and emaciation are
frequently seen.

Question 16

Give reason prevention and control of Loa Loa infections depends on personal prophylaxis than vector control 164

Answer 16

Because control of Chrysops fly is difficult as its breeding site is densely vegetated swampy forests which are difficult to access. So, bites of Chrysops can be avoided by screening, repellents & wearing light colored clothes

Question 17

Give reason the diffuse nature of the cutaneous skin lesions in Leishmania aethiopica infection 187

Answer 17

Spontaneous healing does not occur due to virulent nature of Leishmania aethiopica &
host inability to mount an adequate immune response

Question 18

Give reason Adequate chlorination of swimming pools is needed 219

Answer 18

To avoid infection with water borne parasites as Naegleria, Giardia, Entamoeba & Cryptosporidium.

Question 19

Give reason Recrudescence is seen with toxoplasmosis and falciparum malaria 173 and 211

Answer 19

Due to immunocompromising conditions & inadequate treatment

Question 20

Give reason Surgical removal of palpable Onchocerca nodules on the scalp is preferred 169

Answer 20

To reduce ocular complications of disease such as keratitis, iris glaucoma

Question 21

Give reason Care must be taken upon extraction of Guinea worms from the skin 146

Answer 21

Care must be taken upon extraction of Guinea
Removal of Guinea worm must be by gentle traction over a few days by twisting the worm around a stick taking care not to break to avoid severe allergic reactions

Question 22

Give reason Direct parasitological diagnosis in case of Leishmania tropica skin lesion is done by examination of scraped material taken from the edge of ulcer pg 188

Answer 22

Because the edge of the ulcer countians its diagnostic stage while the center of the ulcer contains dead tissue

Question 23

Give reason Infection with African trypanosomes causes persistent elevation of IgM

pg 200

Answer 23

Due to antigenic variation of the parasites surface coat. T. brucei changes surface coat of trypomastigotes helping them to evade host humoral immune response.
Coat antigens changes when the host’s immune system develops antibodies against it.

Question 24

Give reason Treatment of both partners in trichomoniasis is mandatory pg 216

Answer 24

Because Trichomonas is transmitted by sexual intercourse

Question 25

Give reason Corticosteroids may be needed in the treatment of coenurosis (pg 222)

Answer 25

To help subdue the inflammation after removal of lesion

Question 26

Give reason lice may be responsible for epidemic spread of pathogens (pg 233)

Answer 26

Because lice may leave their host if body temperature rises (fever) or decreases (death) spreading epidemics of diseases

Question 27

House dust samples are very important in diagnosis of some allergic conditions (pg 244)

Answer 27

Collecting dust samples from homes & examining them under microscope for mites. Measure presence of mites & determine infestation level in dust samples

Question 28

Oil-based face cleaners are better avoided, especially in young age groups (pg 242)

Answer 28

Because oil-based cleansers & overuse of creamy preparations supply mites with nourishment helping to increase their number which leads to dermal demodecosis

Question 29

Kidney affection may be reported in some scabies cases (pg 239)

Answer 29

Scabies leads to severe itching & scratching leading to Secondary bacterial infection with Streptococcus Post-streptococcal glomerulonephritis

Question 30

Phlebotomus- borne diseases have a limited geographical distribution (pg 194)

Answer 30

Because Phlebotomus cannot fly long distances & tend to jump

Question 31

Immunodiagnosis may be more important than direct techniques in some cases (pg 25)

Answer 31

1- In early phases of infection
2- In chronic cases where excretion of diagnostic stages is intermittent or these stages are obstructed from reaching sample
3- In cases where parasite numbers are very low
4- Follow up of treatment to establish clearance of parasite

Question 32

Serological tests are more reliable than skin testing (pg 252)

Answer 32

Because skin testing they lack sensitivity & specificity & cannot differentiate between new and old infections & there is a hazard of induce hypersensitivity reactions.

Question 33

Antigen detection may be more useful than antibody detection (pg 252)

Answer 33

Antigen detection is used in diagnosis of recent infections before development of antibodies or in immunocompromised patients. Rapid dipstick tests are developed for some blood protozoa as malaria.

Question 34

Parasite vaccines are difficult to develop (pg 254)

Answer 34

Parasite complex life cycles & lack of full understanding of host-parasite relationships

Sexual reproduction leading to different genotype and phenotypes

Failure to identify specific antigens

Question 35

Malariol is effective against both mosquito larvae and pupae, while Paris green affects larva (pg 160)

Answer 35

Malariol is respiratory poison & causes suffocation of larvae & pupae while Paris green is stomach poison & affects larvae only as pupae don’t feed.

Question 36

Give reason pregnant women should avoid contact with litter boxes or soil.

Answer 36

To avoid infection with sporulated Toxoplasma oocysts which could be present in the cats’ faces, thus putting her foetus at risk of acquiring congenital toxoplasmosis

Question 37

Cystoisosporiasis is occasionally life-threatening.

Answer 37

In immunocompromised patients, severe diarrhoea, malabsorption, steatorrhoea
and loss of weight and dehydration can occur, which may be life threatening
(opportunistic infection).

Question 38

Some individuals may be at more risk of contracting giardiasis.

Answer 38

Hypogammaglobulinaemia, IgA deficiency in the gut, impaired gastric acid secretion or achlorhydria, blood group A and malnutrition in children are factors that increase the risk of giardiasis.