Malaria

1
Malaria

• Tintinallis Chap. 148

2
In General

• It is a protozoan disease caused by the bite of
  the Anopheles mosquito.
• Four species of the Plasmodium genus infect
  humans.(P.Vivax, P.Ovale, P.Malariae,
  P.Falciparum)
• P.Falciparum is the most deadly, and is becoming
  increasingly resistant to antimalarial
  medications.

3
In General

• Transmission occurs in greater portions of
  Central and South America, the Caribbean, sub
  Saharan Africa, the Indian subcontinent,
  Southeast Asia, the Middle East, and Oceania.
• Any patient returning from the tropics with an
  unexplained fever should be suspected.

4
Pathophysiology

• The anopheline (female) mosquito bites releasing
  sporozoites into the hosts blood which are
  carried to liver.
• Asexual reproduction begins in hepatic
  parenchymal cells, and they rupture.
• Merozoites (daughters) are released and invade
  erythrocytes.

5
Pathophysiology

• They mature in the erythrocytes into trophozoites
  and schizonts until the cell lyses and the cycle
  continues.
• Several cycles later, the merozoites develop into
  sexual gametocytes which later develop into
  sporozoites which can infect another host.

6
Pathophysiology

• P. Falciparum, P.Vivax, P.Ovale, and P.Malariae
  differ in(see table 148-2)
• Incubation period
• Reproduction time
• RBC preference
• Morphologic features

7
Pathophysiology

• The asexual intraerythrocytic parasite causes the
  symptoms and pathophysiologic consequences.
• It can be transmitted by direct transfusion of
  infected blood or transplacentally from mother to
  fetus.

8
Clinical Features

• Prodrome of malaise, myalgia, headache, low grade
  fevers, and chills
• Some may have cough, chest pain, abdominal pain,
  arthralgia or diarrhea.
• Eventually, the patient may have severe chills,
  high grade fevers, tachycardia, nausea,
  orthostatic dizziness, and weakness.

9
Physical Exam

• Pts appear acutely ill with high fevers,
  tachycardia tachypnea
• Splenomegaly
• Tender abdomen
• Liver enlargement
• Lymphadenopathy
• Maculopapular rash

10
Labs

• Normochromic normocytic anemia (hemolysis)
• Normal or mildly depressed leukocyte count
• Thrombocytopenia
• Elevated ESR
• Elevated LDH
• Liver and renal function abnormalities
• Hyponatremia, hypoglycemia
• False pos. VDRL

11
Complications

• Splenic enlargement, or rupture
• Autoimmune glomerulonephritis
• Cerebral malaria
• Respiratory failure
• Lactic acidosis
• Profound hypoglycemia

12
Diagnosis

• Giemsa stained thick and thin blood smears to
  view parasites
• At certain stages of the infection the parasites
  may be undetectable.
• If suspicious of malaria, failure to see the
  parasites on the stain is not a reason to not
  treat.

13
Diagnosis

• To exclude malaria completely, repeated smears
  should be done twice daily for two to three days.
• To determine prognosis look for degree of
  parasitemia and whether P. Falciparum is present.

14
P. Falciparum

• Look for small ring forms with double chromatin
  knobs within erythrocyte, and crescent shaped
  gametocyte.
• This should be managed in a hospital setting.

15
Treatment

• Most cases can be handled in an ambulatory
  setting.
• Those that should be hospitalized include those
  infected with P.Falciparum, infants, pregnant
  women, those with significant chronic medical
  problems.

16
Treatment

• Uncomplicated infection with P.Vivax, P.Ovale,
  P.Malariae and Chloroquine sensitive
  P.Falciparum
• Chloroquine phosphate plus Primaquine phosphate
  
• See Table 148-4 for dosing schedules
  
  
  
  
  
  

17
Treatment

• Uncomplicated infection with chloroquine
  resistant P.Falciparum
• Quinine sulfate plus doxycycline plus or minus
  Pyrimethamine Sulfadoxine
• Or, Mefloquine plus doxycycline or
  Atovaquone-Proguanil

18
Treatment

• Complicated infection with chloroquine resistant
  P.Falciparum
• Quinidine Gluconate plus Doxycycline
• See table 148-5 for side affects of meds
• Parasite should decrease within 24-48hrs.
• No asexual forms should be detected 3-4 days
  after treatment.
• Gametocytes may persistent, but do not mean
  treatment failure.

19
Treatment

• Clinical relapses usually occur unless Primaquine
  is used.
• Primaquine should not be given to those that are
  glucose-6-phosphate dehydrogenase deficient.
• Primaquine is not needed with P.Falciparum due to
  the absence of dormant asexual forms in the liver.

20
Prevention

• Anti-mosquito measures
• Antimalarial drugs
• Pyrethrum containing insect spray
• Insect repellent containing DEET
• Appropriate chemoprophylaxis (see table 148-6)
• Malaria vaccines are still in trials