Malaria Flashcards
What percentage of the world is at risk of contracting malaria?
50%
How many million people are infected with malaria per year?
250 million
What percentage of deaths due to malaria occur in Africa?
90%
How many travelers contract malaria per year?
10 000
Which provinces in RSA are malaria infested?
- Mpumalanga
- Limpopo
- KwaZulu Natal
Roughly how many cases of malaria where imported from other countries?
64% (2011)
just know more than half
What type of mosquito carries the malaria parasite?
Female anopheles mosquito
How is the parasite transmitted?
By blood. It enters the human host blood stream after a female anopheles mosquito bites the host and transmits the sporozoites
After the initial injection of the sporozoites, where do they migrate to in the human host?
Through the blood to the liver where they invade hepatocytes and divide to form multinucleated schizonts (pre-erythrocytic stage)
Explain hypnozoites.
- Quiescent (dormant) stage in the liver
- Only in plasmodium vivax and plasmodium ovale
- Assymptomatic
- Get reactivation relapse months after initial infection
Describe the erythrocytic stage in the plasmodium life-cycle.
- Occurs after the pre-erythrocytic stage
- Schizonts rupture
- Release merozoites
- Merozoites invade red blood cells where they are immature trophozoites
Describe the fate of immature trophozoites.
Different paths.
- Mature into mature trophozoites and then multi-nucleated schizonts (which again rupture)
- Differentiate into male and female gametocytes which are then ingested by female anopheles mosquitos
How do plasmodium gameotcytes mature?
- Ingested by female anopheles mosquito
- Develop into sporozoites in mosquito midgut
- Then migrate to the mosquito salivary glands
Briefly describe malarial pathogenesis.
- Digest haemoglobin into haemozoin. RBC’s membrane less deformable whcih leads to haemolysis and splenic clearance (Anaemia)
- Microvascular sequestration where parasite induces formation of sticky knobs on RBC’s because of the expression of proteins like pfEMP-1 (plasmodium falciparum erythrocyte membrane protein 1). RBC’s bind to vessel walls which leads to obstruction of flow and endothelial damage and inflammation
- Cytokine release (TNF and IL) which cause systemic inflammation response syndrome (activates coagulation cascade)
What are the uncomplicated clinical features of malaria?
- Ambulant patient
- Vommiting
- No jaundice
- Normal mental state
- Normal respiratory rate
- No organ dysfunction
What are the complicated clinical features of malaria?
- Cerebral malaria (microthrombi in brain vessels)
- Severe anaemia
- Renal failure
- Respiratory failure
- Jaundice (Liver dysfunction)
- Metabolic acidosis
- Hypoglycaemia
- Bleeding
- Blackwater fever
- Hyperparasitaemia
What are the risk factors in contracting malaria?
- HIV (immunocompromised patients)
- Pregancy
- Children (under 5yrs)
- Splenectomised patients
What tests need to be done to confirm the diagnosis of malaria?
- Microscopy (Giema-stained smears)
- Rapid antigen test
- PCR
In terms of malaria diagnosis, what are important factors to note?
- Febrile illness
- Travel/exposure to endemic area
- Fever, chills, myalgia, headache, vomitting and diarrhoea
What is the RSA malaria elimination target date? How is it to be met?
2018
- ACT
- DDT
- Bednets
- Improved surveillance
How are mosquito bites prevented?
- Repellants (min 30% DEET)
- Insecticides
- Protective clothing
- Insecticide impregnated bednets
What is the standard treatment for non-falciparum plasmodium parasites?
- Oral chloroquine
2. Primaquie (contra-indicated in pregnancy but prevents relapse in liver)
What is the standard treatment for uncomplicated plasmodium falciparum parasitic infections?
- Artemetherlumefantrine (Coartem)
- Artemiscin (ACT - prevent drug resistance)
- Oral quinine + doxycycline / clindamycin
What is the standard treatment for complicated plasmodium falciparum parasitic infections?
- IV Artesunate (followed by an oral Coartem course)
2. IV Quinine (loading dose and maintenance regieme) + doxycycline / clindamycin
List four prophylactic anti-malarial drugs.
- Mefloquine
- Doxycycline
- Atovaquone (proguanil)
- Malanil
