Malaria profoma Flashcards
What is malaria?
A parasitic infection caused by protozoan parasites of the Plasmodium family.
- Most life-threatening & dangerous member of the family is Plasmodium falciparum
Spreads through bites from the female Anopheles mosquitoes that carry the disease.
What are the 5 types of Malaria?
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
Epidemiology of malaria
found in tropical regions like Africa & Asia
malaria isn’t found in UK
risk factors are pregnancy, children, elderly, auto immune & absent spleen
Plasmodium falciparum accounts for 75% of malaria cases in the UK
Pathogenesis of malaria
- Female Anopheles mosquito becomes infected when it feeds on human blood containing gametocytes (the sexual form of the malarial parasite).
- Inside the mosquito gut, the gametocytes will mature & fuse forming a zygote → ookinete → oocyst → sporozoites
- The sporozoites are released & migrate to salivary glands of mosquito.
- Female Anopheles mosquito bites a human, injecting the Plasmodium parasite into the blood
- The sporozoites in the blood enter the parenchymal liver cells. Thousands of new parasites are formed, known as merozoites.
NOTE: P. vivax &P. ovale may persist in liver cells as dormant forms, hypnozoites, capable of developing into merozoites months or years later.
- The merozoites infect red blood cells & asexually reproduce & multiply, producing schizonts (a cell that bursts).
- Eventually, RBCs will rupture leading to more merozoites in blood & causing haemolytic anaemia
NOTE: Schizont rupture causes fever & periodicity is dependant on the species.
- Some merozoites go on to develop into gametocytes so cycle starts again.
NOTE: view diagram of lifecycle on notes!
Presentation of malaria
Insidious - gradual onset but in a harmful way.
Anaemia - pale, fatigued, weak, lightheaded, shortness of breath.
1-4 weeks after travel to endemic area - important to get a travel history.
Common symptoms:
- Cough
- Fever
- Sweats
- Rigor - shaking chills
- Malaise
- Myalgia & arthralgia
- Headache
- Anorexia
Less common symptoms:
- Abdominal pain
- Jaundice as bilirubin is released during the rupture of RBC.
- Pallor
- Nausea & Vomiting
- Seizures - suggests P. falciparum infection
Severe symptoms of malaria
- Coma, reduced consciousness or fits (cerebral malaria)
- Hyperpyrexia
- Convulsions
- Severe anaemia
- Acute kidney injury
- Metabolic acidosis
- Shock (caused by sepsis)
- Aspiration pneumonia
Investigations for malaria
- Giemsa-stained thick & thin blood smears - test of choice.
- Must be done 3 times: at diagnosis, 24 hours & 48 hours later.
- A thick blood smear is a drop of blood on a glass slide.
- A thin blood smear is a drop of blood that is spread across a large area of the slide. - Lateral flow tests - helpful in detecting the malarial antigen.
- FBC - May show thrombocytopenia, anaemia, variable white cell count.
- Serum electrolytes, urea & creatinine - renal failure may be present in severe infection.
- Serum LFTs - may show elevated bilirubin or elevated aminotransferases.
- Serum blood glucose -hypoglycaemia may occur when patient is on quinine therapy.
- Urinalysis -may show trace to moderate protein; urobilinogen & conjugated bilirubin may be present.
- Arterial blood gas - may demonstrate metabolic or lactic acidosis in severe disease.
Management for malaria
- IV artesunate - for severe or complicated malaria.
- IV quinine - can be used if artesunate cannot be obtained w/out delay.
- Oral artemisin combination therapy - for uncomplicated P. falciparum infection.
- Chloroquine - for uncomplicated P. vivax, P. Ovale, P. Knowlesi or P. Malariae.
- Primaquine - used to kill hypnozoites of P. Vivax or P. Ovale (prevents relapses).
NOTE: Antiobiotics & antifungals have no benefit for plasmodium parasites.
Prevention:
- Take antimalarial prophylaxis
- Mosquito nets & barriers when sleeping
- Mosquito spray
- Seek medical advice if symptoms develop
Prognosis for malaria
Excellent if malaria has been diagnosed early then treated appropriately.
Delays in diagnosis & treatment can lead to malaria associated morbidity & mortality.
Most patients w/ uncomplicated malaria show improvement within 48 hours after initiation of treatment.
poor prognosis w/ Plasmodium falciparum & can have high mortality rate if left untreated.
