Malaria

Question 1

Malaria organism

Answer 1

Plasmodium protozoa

• P. falciparum (most severe)
• P. vivax
• P. ovale
• P. malariae
• P. knowlesi

Question 2

Malaria vector

Answer 2

female Anopheles mosquito

Question 3

MC way to acquire malaria

Answer 3

mosquito bite in endemic area (tropical and subtropical areas)

Question 4

High risk groups for malaria infection

Answer 4

• young children
• pregnant women
• travelers/migrants

Question 5

Is malaria in the US??

Answer 5

• 1,700 cases a year
• Anopheles mosquito is in the US
• risk of resurgence

Question 6

4 ways Malaria is transmitted

Answer 6

• bite from female Anopheles mosquito (MC)
• Airport malaria: mosquito on plane from endemic to non endemic area
• Congenital
• Transfusion (rare in US)

Question 7

Pathophysiology

Answer 7

• two hosts: mosquito and human
• Anopheles transmits plasmodia (in saliva) into host when bite
• In human, parasite grow and multiply in liver and then RBC
• in RBC, grow and destroy cells, release merozoites which invade other RBC
• RBC cytolysis = release toxic metabolites = flulike sx for host
• Some differentiate into gametocytes which are ingested by another Anopheles, grow and multiply into new sporozoites and get into saliva, start cycle over

Question 8

P. Falciparum

Answer 8

• Most severe
• microvascular effects
• only type can cause death if untx

Question 9

P. vivax

Answer 9

• Most West Africans have resistance dt lack of Duffy blood group on RBC so plasmodium cannot attach
• generally causes less severe dz

Question 10

P. ovale

Answer 10

Less common

- tertian pattern of fever: q 48 hour spikes

Question 11

P. Malariae

Answer 11

• may cause no acute sx
• can lead to immune mediated nephritic or nephrotic syndomre
• fever quartan pattern q 72 hours

Question 12

P. knowlesi

Answer 12

• SE asia
• Monkey is intermediate **
• rare but can cause dz in humans

Question 13

Incubation

Answer 13

• approx 4 weeks
• vivax and ovale: weeks to months after initial infection, hypnozoite form (can linger in liver longer). Have to treat this stage separately
• shorter incubation falciparum
• longer incubation malariae

Question 14

common S/sx

Answer 14

• HA
• fever, shaking chills, sweats (q48-72 hr depending on species)
• cough
• fatigue
• malaise
• arthralgia
• myalgia

Question 15

less common s/sx

Answer 15

• anorexia/lethargy
• n/v
• diarrhea
• jaundice

Question 16

PE

Answer 16

• splenic/liver enlargement
• fever
• mild jaundice
• cerebral malaria (coma?)
• anemia
• resp abnl
• renal failure
• • no rash or lymphadenopathy

Question 17

Dx

- general tests

Answer 17

• history!! Travel
• Labs: blood culture, CBC, iron panel, CMP, liver/renal fn tests, electrolytes, LDH
• CXR if resp sx
• CT if CNS sx

Question 18

Dx

- malaria specific tests

Answer 18

• Giemsa stained peripheral blood smear. multiple smears needed
• Rapid dx tests via dipstick
• PCR assay (to confirm after blood smear)

Question 19

ABCDs of malaria

Answer 19

• Awareness: recognize malaraia
• Bite prevention: control mosquitoes, use a net
• Chemo prophylaxis: use preventative meds
• Dx: early recognition

Question 20

Malaria prevention

Answer 20

• long clothing to reduce exposed skin (esp dusk to dawn)
• topical repellants
• other repellants
• • no chemoprophylaxis regime = 100% protection!!