Malaria and Other Sporozoa

Question 1

Describe the general plasmodium lifecycle

Answer 1

1. Anopheles mosquito bites and introduces sporozoites
2. asexual reproduction in hepatocytes
3. hepatocytes rupture and plasmodia enter RBC’s
4. RBC’s rupture
5. plasmodia enter other RBCs or are taken up by mosquito at a blood meal to enter sexual reproduction stage

Question 2

What plasmodium species can enter a dormant hepatic phase (hypnozoites)

Answer 2

P. vivax and P. ovale

Question 3

What plasmodium species is most likely to cause death if untreated

Answer 3

P. falciparum

Question 4

What 2 plasmodium species is the Binax rapid dx test sensitive to.

Answer 4

P. falciparum and P vivax

Question 5

Describe P falciparum in terms of distribution, what RBCs it infects, periodicity of fever/chills, other symptoms, and microscopy/Dx

Answer 5

Distribution: tropical and subtropical regions

RBC’s infected: any stage

Periodicity of fever/chills: starts as every 24 hrs then becomes tertian (36-48 hrs)

Other symptoms: cerebral malaria, blackwater fever (kidney damage from rapid RBC destruction) and death

Dx: Thick and thin smears with rings at the edge of the cell membrane, can have multiple rings d/t RBC being infected by multiple organisms, RBCs are not distorted , gametocytes have crescent shape

Question 6

Describe P. knowlesi in terms of distribution, periodicity of fever/chills, other symptoms, and microscopy/Dx

Answer 6

Distribution: Malaysia in humans, but is a parasite in old world monkeys

RBC’s infected: all stages

Periodicity of fever/chills: Quotidian (24 hr)

Other symptoms: because of short cycle can have hyperparasitemia

Dx all developmental stages can be seen in peripheral blood

Question 7

Describe P. vivax in terms of distribution, periodicity of fever/chills, other symptoms, and microscopy/Dx

Answer 7

Distribution: widest distribution of any plasmodia, includes tropic, subtropics and temperate regions. Majority of infections in S. America and S.E Asia

RBC’s infected: young immature RBCs

Periodicity of fever/chills: 48 hrs

Other symptoms: can lead to benign tertian malaria which is a chronic infection for years because symptoms are mild

Dx: thick and thin smears bewteen fever/chill cycle (paroxysms), this is when greatest # of organisms are present. RBCs are enlarged and contain Schuffner dots (numerous pink dots)

Question 8

What is the most prevalent human plasmodia

Answer 8

P. vivax

Question 9

Describe P. ovale in terms of distribution, other symptoms, and microscopy/Dx

Answer 9

Distribution: Tropical Africa

RBC’s infected: young immature RBCs

Other symptoms: benign tertian malaria but only last 1 year

Dx: . Thick/thin smears. RBCs become enlarged and contain Schuffner dots (numerous pink dots) w/ ragged cell border

Question 10

Describe P. malariae in terms of distribution, periodicity of fever/chills, other symptoms, and microscopy/Dx

Answer 10

Distribution: subtropic and temperate regions

RBC’s infected: mature RBC’s w/ rigid cell membranes

Periodicity of fever/chills: longest incubation period of any plasmodia usually 18-40 days but could be months then quartan 72 hrs.

Other symptoms: long lasting infection

Dx: conform to size shape of RBCs, occasional Zeimann dots (reddish granules), bar and band forms and rosette shizont

Question 11

Describe general lifecycle of Babesia sp

Answer 11

Humans are accidental host, typically infects deer cattle and rodents

Transmitted by Ixodes dammini ticks

Infectious form is pryriform bodies, that enter RBCs and multiply by binary fission which then rupture RBC and infect other RBCs

Question 12

Describe Babbesia sp in terms of distribution, what causes it, symptoms, how to dx, and prevention

Answer 12

Distribution: Africa, Asia, Europe and North America

Cause: tick bite or blood transfusions ( no blood screening test so anyone who has hx can not give blood)

Symptoms: general malaise, sweating, hemolytic anemia, possible renal failure hepatosplenomegaly in ate infection

DX: blood smears

Prevention: tick prevention or immediate tick removal

Question 13

Describe Toxoplasma gondii in terms of distribution, what causes it, symptoms, how to dx, and prevention

Answer 13

Distribution: Ubiquitous in humans

Cause:

• ingestion of of oocysts from contaminated meat, fecal oral d/t cat feces
• organ transplant/blood tranfusions
• placental transmission

Symptoms:

• acute infection: typically benign but is fever, headache, fatigue
• chronic: lymphadenitis, rash, hepatitis, myocarditis, encephalomyelitis, congenital issues

DX: serologic profile > 1:16 twice

Prevention: avoid cat feces

Question 14

Describe Leishmania in terms of distribution, what causes it, symptoms, how to dx, and prevention

Answer 14

Distribution: Africa, middle east, India, S. America

Cause: female sand flies

Symptoms:
-cutaneous (middle east): red, pruritic papule that enlarges and ulcerates leaving a disfiguring scar

-visceral (India Nepal, Brazil, Sudan): did not talk about

DX: clinical presentation and biopsy

Prevention: prompt treatment and control of host/vectors

Question 15

True or False visceral leishmaniasis is a zoonotic dz except for in India

Answer 15

True, it is known as kala-azar and is spread by human to human

Question 16

What are the 2 forms of trypanosomiasis and how are they transmitted.

Answer 16

African trypanosomiasis (African sleeping sickness) , transmitted by Tsetse flies who are infected by either Trypanosom b. gambiense or Trypanosom b rhodesiense

American trypanosomiasis (Chagas dz), transmitted by reduvviid (kissing) bugs who are infected w/ Trypanosoma Cruzi

Question 17

Describe Gambian Sleeping sickness in terms of distribution, what causes it

Answer 17

Distribution: West and Central Africa

Cause: bite of Tsetse fly infected w/ Trypanosom b. gambiense which live by stream banks

Symptoms: ulcer at fly bite, lymph nodes then enlarge, myalgia and Winterbottom sign develops (enlargement of posterior lymph nodes)

Question 18

Describe Rhodesian Sleeping sickness in terms of distribution, and what causes it

Answer 18

Distribution: East Africa, especially in cattle raising countries (cattle and sheep act as reservoirs)

Cause: bite of Tsetse fly infected w/ Trypanosom b. rhodesince

Symptoms: shorter incubation when compared to T.b gambiense. Fever chills rigours occur rapidly. renal damage and myocarditis and fulmaniting dz can cause fatal illness usually withh 9 to 12 months,

Question 19

Describe Trypanosoma Cruzi in terms of what disease it causes, distribution, what causes it, symptoms, how to dx, and prevention

Answer 19

Dz: Chagas

Distribution: South and Central America

Cause: bite from infected reduvviid (kissing) bugs or ingesting contaminated water/fruits/vegs

Symptoms:

acute: chagoma at bug bite, rash, orbital and facial edema (Romana sign) , fever, malasia, CNS involvement then possibly death
chronic: if pt does not die =megacardia, hepatosplenomegaly

DX: blood smears

Prevention: education