Dr. Libman -- Parasitology 2: Malaria Flashcards
Describe the epidemiology of malaria
- 500 million febrile episdoes per year
- Millions of deaths per year
- Extremely widespread until 20th C
- Exceptions include Sub-saharan africa (resurgent disease since 1980’s - 1990’s)
3 causes of sub-saharan africa having resurgent malaria since 1980-1990’s
- Emergent drug resistance
- Few affordable alternatives
- Failed mosquito control
Organism responsible for malaria
*Plasmodium *spp. protozoan
Malaria vector
*Anopheles *mosquito
Only reservoir of malaria
Humans
Describe the distribution of malaria (5 locations)
- Central America
- Tropical South America
- Sub-Saharan Africa
- South Asia
- South-east Asia
6 organisms that are a part of phylum apicomplexa
- *Plasmodium *spp.
- Toxoplasma gondii
- Cryptosoporium parvum
- Isospora belli
- Cyclospora cayatenensis
- Babesia microti
5 organisms belonging to *Plasmodium *spp.
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
Compare *P**. knowlesi *to its familial counterparts
- Same morphology as P. malariae
- High parasitemia and mortlaity like P. falciparum
Give a general overview of the lifecycle of malaria (9 steps and 1 aside)
- Human has malaria
- Mosquito takes blood
- Mosquito bites someone else –> malaria in that person
- Rapid intake to liver (developmental phase)
- Enter blood
- Invade RBCs
- Mulitplication of organism
- Red cell rupture
- More red cells infected
NOTE: a few become gametocytes instead –> mosquito eats –> mate in mosquito to become another malaria infection to be transmitted
Protozoa that is NOT a zoonosis
Entamoeba histolytica
What is a sporozoite
Form of malaria transmitted by the mosquito, which enters the liver
What is a schizont?
Form of malaria that infects the red blood cells to multiply after having developed in the liver
RBC receptor for P. vivax
Duffy/Antigen
Area of the world that is Duffy AG negative and what this means
West Africa = immune to vivax (but has evolved to become a different type of plasmodium)
11 symptoms of malaria
- Chills
- Rigors
- Fever
- Perspiration
- Fatigue
- Headache
- Delirium
- Confusion
- Coma
- Shortness of breath
- Jaundice
2 signs of malaria
- Anemia
- Splenomegaly
Describe the fever pattern of malaria
- Vivax = tertiant (every second day)
- Malariae = Quartent (every third day)
- Falciparum = Quotidian (daily spikes of fever that persist for a few days and occasionally break every couple of days)
How does a fever pattern occur with malaria?
Synchronized parasites
What is the cause of a fever coming back from the tropics?
Malaria until proven otherwise
7 reasons for death due to malaria, starting with the most common cause
- Cerebral malaria (50%)
- ARDS (46%)
- Renal failure (40%)
- Hematological (13%)
- Shock (10%)
- Sepsis (5%)
- Ruptured spleen (5%)
Reason for sepsis due to malaria
Leaky blood vessels and ischemia in the gut
General timeline of fatality from onset of symptoms (fever) in malaria
A week
What is black water fever?
Malaria with hemolysis producing blackened urine (quinine can aggravate)
Why must you not underestimate the results of venous blood samples when testing for malaria?
Deformed red cells express malaria antigen and get sequestered into small blood vessels (microcirculation) so cannot detect in blood sample
Pathophysiology of cerebral malaria (4 points)
- Sticky RBC knobs
- High TNF levels
- Poor deformability of infected RBCs
- Increased endothelial permiability
2 effects of high TNF levels in cerebral malaria
- Vascular endothelial adhesiveness
- Direct CNS effects
3 types of modulators of clinical severity of ARDS in malaria
- Transmission intensity
- Co-infections
- Host polymorphisms
What does an EBV co-infection in infancy lead to?
Burkitt’s lymphoma
Effect of hemoglobinopathy on risk of malaria infection
Decrease
What is a reliable indicator of malaria in a regoin where malaria is not apparent in adults?
Measurement of kids’ spleen sizes
Why might a region seem unaffected by malaria?
Adults have developed a partial immunity to malaria due to constant re-infection, so symptoms may be very minimal despite high transmission rates
2 types of north american mosquitoes that can act as a vector of malaria
- Anopheles freeborni
- Anopheles quadrimaculatus
How was malaria diagnosied in 1849
Fever chart
6 lab findings of malaria
- CBC
- Thrombocytopenia
- Leukopenia
- LFT = high liver enzymes
- Prothrombin time = increased
- Glucose = decreased
- Serum K+ = increased
- Creatinine = increased
Antimalarial treatment in a chloroquine sensitive area
Chloroquine phosphate 250 mg tabs:
- 1,000 mg STAT
- 500 mg 6 hours later
- 500 mg daily for 2 days
Antimalarial prophylaxis in chloroquin sensitive area (2)
- Chloroquine
- Daraprim
- all chloroquine resistant regions’ drugs
Antimalarial treatment in chloroquine resistant area (5)
- Quinine + tetracycline OR clindamycin OR Fansidar (sulfadoxine and pyrimathamine)
- Artesunate combination therapy
- Doxycycline
- Malarone (atovaquone/proguanil)
- Mefloquine (a quinoline methanol)
6 antimalarial prophylaxis in chloroquine resistant area
- Mefloquine (250 mg weekly)
- Atovaquone/proguanil (Malarone) daily
- Doxycycline 100 mg daily
- Primaquine 30 mg base daily
- Chloroquine 500 mg weekly and paludrine 200 mg daily
- Permethrin treated bednet nightly
3 ways drugs used for malaria prophylaxis can work
- Kill parasites in liver (causal prophylaxis)
- Kill asexual parasites in RBCs (suppressive prophylaxis)
- Kill sexual parasites (gametocytes) in RBCs (gametocytocidal prophylaxis)
Chloroquine sensitive areas (5)
- Central America
- Argentina
- Most of the Middle East
- Southeast China
- Dominican Republic/Haiti
Reason for using combination therapy in chloroquine resistant malaria
- Drug 1 brings down malaria quickly, but is poor at eradicating it
- Drug 2 acts more slowly, but eradicates malaria from the body
Mefloquine and chloroquine resistant regions
- Northwest Thailand (bordering Myanmar)
- Northwest Cambodia and around Thailand border
When to use exchange transfusion as a treatment of severe malaria (2 cases with 6 sub-points)
- 10% + parasitemia
- 5% + parasitemia
- With complications of shock
- Abnormal levels of consciousness
- Pulmonary edema
- Renal failure
- Cardiac dysfunction
- High volume diarrhea or vomiting
3 types of measures to prevent malaria
- Mosquito avoidance
- Mosquito killing
- Plasmodium killling
6 ways to avoid mosquitoes
- Understand evening and night behavior
- Mosquito nets
- Air conditioning
- Screens
- Mosquito repellents
- Pyrethrum coils
3 ways to kill mosquitoes
- Destroy breeding sites
- Fog spraying
- Residual spraying
48 hour cycle of the life of a mosquito (6)
- Adult bites at night
- Adult female rests (on inside wall)
- Lay eggs (water surface)
- Larva (wter surface)
- Pupa (water surface
- Adult searches for blood meal
3 antimalarials that are derived from plants
- Artesunate
- Pyrethroids
- Quinine