Presentation can be vague, any or all of wide variety of symptoms.
Always should be considered in unwell patients returning from or having passed though endemic areas
Parasite is a plasmodium (protozoan). 4 species infect humans:
- P.falciparum (80% cases worldwide, highest mortality)
By the bite of the female anopheline mosquito
(can also be aquired transplacentaly, by transfusion or inoculation.)
Life Cycle of parasite
- Very important tropical disease – occurs throughout tropics and subtropics at altitudes below 1500m
- 0.5-2 million deaths per year (mostly <5yrs)
Red blood cells genetic factors
- Sickle cell trait (HbS) is relatively protected against P. falciparum malaria (àbiologic advantage)
- Duffy blood group negative red blood cells are resistant to infection by P. vivax.
Acquired immunity can develop after repeated attacks. A person can still be infected by malaria parasites but may not develop severe disease. (this is usually lost In pregnancy).
- Haemolysis of RBCs and adherence of infected RBCs to capillaries and cytokine release.
- In falciparum, RBCs containing schizonts adhere to capillary epithelium in the brain, kidney, liver lungs and gut vessels become congested
- Organs anoxic.
- Rupture of schizonts liberate toxic and antigenic substances that may cause further damage
Thick and thin blood films. Look for trophozoites and % RBC infected. High % (>30%) has high mortality
Quinine in mainstay of treatment (IV if >2% RBC infected)
Resistance of p.falciparum to chloroquine in widespread)
Supportive measures in severe disease.
- Mosquito nets and well covering clothing
- Insect repellant and indoor spraying (ie DDT)
- Prophylaxis medications
- Doxycycline (cheapest, taken daily for 2 weeks prior to visiting and 4 weeks after returning from endemic area, SE include sunlight hypersensitivity, nausea and diarrhea).
- Malarone (most expensive, taken daily for 2 days before and 7 days after trip, fewer side effects)
- Larium (combination medication, taken weekly for 2 weeks prior to visiting and 4 weeks after returning from endemic area contraindicated in those with history of epilepsy or psychiatric disorders due to neuropsychiatric side-effects such as anxiety and hallucinations)