Malaria Flashcards
What is malaria?
Malaria is a mosquito borne-disease Caused by a parasite called plasmodium, which is transmitted via the bites of infected mosquitoes
Malaria parasites infect what organs in the body?
In the human body ,the parasites multiply in the liver, and then infect red blood cells
What is malaria transmitted by?
Transmitted by bite of infected female anopheline mosquito
Where is malaria most common?
Malaria is restricted to areas where these mosquitos can breed
- tropics between 60N and 40S (except areas > 2000m high)
e.g. Africa, India, Far East, S America
Describe the plasmodium phase?
- timespan of plasmodium phase that occurs within mosquito depends on ambient temperature
- lasts 8-30 days
- at temps < 16-18C mosquito does not live long enough for this phase to be completed
Other modes of malaria transmission?
- blood transfusion
- needle accidents
- rarely mother to foetus
Life cycle of malaria infection?
Pathology of malaria?
- Events start with bite of infected anopheles mosquitoes, Sporozoites enter liver in 1 hour infect the parenchymal cell.
- The most pronounced changes related to malaria involve the blood and the blood-forming system, the spleen and the liver.
Importance of red blood cells in malaria pathology?
- Red blood cells are the principal sites of infection in malaria
- All the clinical manifestations are primarily due to the involvement of red blood cells
What are the pathophysiological factors that are involved in the development of severe malaria?
- parasite biomass, malaria toxin(s) and inflammatory response
- cytoadherence, rosetting and sequestration
- altered deformability and fragility of parasitized erythrocytes
Describe the parasite biomass in the pathogenesis of malaria?
P. falciparum has the ability to invade RBCs of all ages, and with repeated cycles of development within the red cells
Describe cytoadherence in the pathogenesis of malaria?
- Structural changes in the infected red cells and the resulting increase in their rigidity and adhesiveness are major contributors
- These RBCs adhere to the capillary and postcapillary venular endothelium in the deep microvasculature
Describe rosetting in the pathogenesis of malaria?
The infected red cells also adhere to the uninfected red cells, resulting in the formation of red cell rosettes
Describe sequestration in the pathogenesis of malaria?
Cytoadherence leads to sequestration of the parasites in various organs
e.g. the heart, lung, brain, liver, kidney, intestines, adipose tissue, subcutaneous tissues, and placenta.
What are the 5 malaria species?
- falciparum
- vivax
- ovale
- malariae
- knowlesi
What types of RBC are infected by falciparum?
Younger cells, but can infect cells of all ages
- Most virulent and predominates in Africa
What types of RBC are infected by vivax and ovale?
Reticulocytes
- Common in central America and Indian subcontinent
- Causes relapsing malaria
What types of RBC are infected by malariae and knowlesi?
older cells
Symptoms of uncomplicated malaria?
First symptoms are non specific:
1. Headache, Lassitude, Fatigue, Abdominal discomfort, muscle and joint aches, diarrhea, nausea, vomiting
2. Followed by fever (irregular at first), chills, rigors, perspiration, anorexia
3. In some cases mild anemia, palpable spleen and slight enlargement of liver are also present
Complications of falciparum malaria?
CHAPLIN
Cerebral malaria/coma
Hypoglycemia
Anemia
Pulmonary edema
Lactic acidosis
Infections
Necrosis of renal tubules (ATN)
Acute complications of malaria?
renal impairment: creatinine > 3mg/dl
jaundice: bilirubin > 43
transaminases: > 3x normal
acidosis: plasma bicarbonate < 15mmo/l
venous lactate: > 5mmo/l
hypoglycaemia: < 2.2 mmol
Severe anaemia
Decreased platelet count
Prolonged INR
Haemoglobinuria
Elevated muscle enzymes( CPK) myoglobin
Risk factors for severe malaria?
- Malawians returning from non-malarious country (>1 year outside)
- Expatriates
- Pregnant women
- Advanced HIV/AIDS individuals not on treatment (take note that acute Malaria increases HIV viral load)
- Splenectomised individuals
Chronic complications of malaria?
- tropical splenomegaly
- quartan malarial nephropathy
What is tropical splenomegaly?
abnormal immunological response to repeated infections – with massive splenomegaly, hepatomegaly