Parasites I

Question 1

Giardiasis Transmission

Answer 1

Cycle:

1. Cysts exit via feces
2. Into water supply
3. Drank
4. Cysts  trophoz.
5. Trophoz.  cysts

Also possible:
hot tub, swimming pool, etc.
fomites
contaminated food

Most common in children
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Question 2

Giardiasis Symptoms

Answer 2

Most are Asymptomatic, but…

Acute:
Watery diarrhea
Abdominal pain
Flatulence
Abnormal stools (smells, loose)

Chronic:
Prolonged acute symptoms
Failure to absorb nutrients  malnutrition problems

Question 3

Giardiasis Treatment

Answer 3

Metronidazole
tinidazole
Drugs are antibiotics that work

Question 4

Giardiasis Prevention & Control

Answer 4

Prevention:
Hygiene
Personal
Community level:
Waste management
Clean water supplies
Vaccine (only for livestock)

Question 5

Trypanosoma brucei Two strains:

Answer 5

T. brucei gambiense (West Africa)

T. brucei rhodesiense (East Africa)

Question 6

T. brucei Life Cycle

Answer 6

Tsetse fly (Glossina spp.)

3-stage life cycle:
Fly midgut
Fly salivary glands
Human blood

Switches surface antigens every cycle

Question 7

Sleeping Sickness Transmisstion

Answer 7

1. Tsetse fly bite
2. Chancre forms
3. Parasite moves to blood, lymph
4. To CNS

often spreads to and damages all organs,
even though it never invades the cells;
immune system can’t clear it

Question 8

Sleeping Sickness Symptoms: Clinical Features

Answer 8

Early:
Fever
Weakness

Later:
Disrupted Sleep
Won’t Eat
Coma (leading to death

Question 9

Sleeping Sickness Treatment

Answer 9

Drugs are Toxic

Early Stages:
Pentamidine
Suramin

Later Stages:
NCET (nifurtimox-eflornathine)

Treatment is not good

Question 10

Sleeping Sickness Prevention & Control

Answer 10

Insect control
Insecticides
Physical modification of environment (e.g. standing water)

Vaccine untenable (pathogen switches surface antigens constantly)

Question 11

Five species cause malaria:

Answer 11

P. falciparum
P. knowlesi (just recently added)
P. malariae
P. ovale
P. vivax

Question 12

Malaria Transmission

Answer 12

From bite of infected female Anopheles mosquito

Less common:
Congenital
Shared needles
Blood transfusions

Question 13

Malaria Symptoms

Answer 13

First attacks look like flu

Each episode:
Fever
Chills
Sweating     
Headache
Weakness/Fatigue

Delirium is common

Cold stage-> Hot Stage-> Wed Stage

Question 14

Blackwater Fever

Answer 14

P. falciparum-related
Rare
Erythrocytes lysed; hemoglobin into urine
Why it’s a big problem:
Anemia
Erythrocytes become rigid  block blood vessels (ischemia)  organ problems

Question 15

Malaria Treatment

Answer 15

Historically: quinine only

Today:
Quinine group drug +
Artemisinin or derivative

Question 16

Malaria Prevention & Control

Answer 16

Mosquito control:
Insect netting:
Insect repellant
Fogging
Prophylactic antibiotics
Vaccine (not yet there)