24 Questions
What is the primary cause of malaria in humans?
Parasitic protozoans of the genus Plasmodium
Which of the following Plasmodium species is most likely to invade red cells of all ages?
P. falciparum
What is the term for the sexual forms of the malarial parasite?
Gametocytes
Where do sporozoites enter after being injected into the human body by the mosquito?
The liver
What is the most effective treatment for P.falciparum infection?
Artemisinin-combination therapy (ACT)
What is the result of the rupture of schizonts in the human body?
Fever
Which of the following is a characteristic of P. falciparum malaria?
Widespread organ damage
For treatment of malaria during pregnancy, what is recommended in the 1st trimester?
Quinine plus clindamycin
What is required for treatment of P.vivax infections?
Both treatment of blood stages and clearance of liver forms
What is the term for the dormant forms of P. vivax and P. ovale in liver cells?
Hypnozoites
What is the adaptation that has influenced human evolution in areas where malaria is prevalent?
All of the above
What is the treatment of choice for complicated P.falciparum malaria?
Intravenous artesunate
What is the recommended chemoprophylaxis for malaria in areas with chloroquine resistance?
Doxycycline
What is the recommended chemoprophylaxis for malaria in areas without chloroquine resistance?
Chloroquine
What is NOT an effective method of prevention of malaria?
Electronic mosquito repellents (EMRs)
What is essential to confirm the diagnosis of malaria?
Thin film
Why are some West Africans and African-Americans protected against P.vivax malaria?
They lack the Duffy blood group
What is the characteristic fever pattern of P.vivax and P.ovale infections?
Fever every two days (tertian fever)
What is a common complication of P.falciparum malaria?
All of the above
What is the purpose of thick and thin blood films in diagnosing malaria?
To diagnose low-level parasitaemia
Why does P.falciparum not grow well in red cells that contain haemoglobin F?
Haemoglobin F is more resistant to parasite invasion
What is a long-term complication of P.malariae infection?
Glomerulonephritis and nephrotic syndrome
What is the characteristic of P.falciparum infection?
Recurrent fever every 36-48 hours or a less pronounced and almost continuous fever
What is a severe manifestation of P.falciparum malaria?
All of the above
Study Notes
Malaria
- Malaria is a mosquito-borne infectious disease caused by parasitic protozoans of the genus Plasmodium.
- The four species of Plasmodium that cause malaria in humans are:
- Plasmodium falciparum
- P. vivax
- P. ovale
- P. malariae
- Malaria is prevalent in tropical and subtropical regions due to ideal habitats for mosquito larvae.
Life Cycle of the Malarial Parasite
- The female anopheline mosquito becomes infected when it feeds on human blood containing gametocytes.
- Sporozoites develop in the mosquito's salivary gland and are transmitted to humans through a bite.
- Sporozoites disappear from human blood within half an hour and enter the liver.
- After some days, they leave the liver and invade red blood cells, starting asexual cycles.
Pathology
- Red cells infected with malaria are prone to haemolysis, which is most severe with P. falciparum.
- P. vivax and P. ovale invade reticulocytes, while P. malariae invades normoblasts.
- In P. falciparum malaria, red cells containing trophozoites adhere to vascular endothelium, causing widespread organ damage.
Clinical Features
- The classic symptom of malaria is paroxysm, a cyclical occurrence of sudden coldness, shivering, and then fever and sweating.
- P. falciparum infection can cause recurrent fever every 36-48 hours or a less pronounced and almost continuous fever.
- P. vivax and P. ovale infections cause tertian fever, occurring every two days.
- P. malariae infection causes quartan fever, occurring every three days.
Complications of P. falciparum Malaria
- Coma (cerebral malaria)
- Hyperpyrexia
- Convulsions
- Hypoglycaemia
- Severe anaemia
- Acute pulmonary oedema
- Acute renal failure
- Spontaneous bleeding and coagulopathy
- Metabolic acidosis
- Shock
- Aspiration pneumonia
- Hyperparasitaemia
Diagnosis
- Thick and thin blood films are used to diagnose malaria.
- Immunochromatographic tests for malaria antigens, such as OptiMal, can also be used.
- DNA detection (PCR) is a more accurate test, but it is costly and requires special laboratory equipment.
Treatment
- The most effective treatment for P. falciparum infection is artemisinin-combination therapy (ACT).
- Additional antimalarials used in ACT include amodiaquine, lumefantrine, mefloquine, or sulfadoxine/pyrimethamine.
- For P. vivax, P. ovale, and P. malariae infections, treatment is with oral chloroquine.
- Treatment of P. vivax requires both treatment of blood stages and clearance of liver forms with primaquine.
Prevention
- Chemoprophylaxis of malaria can be achieved with chloroquine, mefloquine, or doxycycline.
- Insecticide-treated bed nets (ITNs) and electronic mosquito repellents can also be used for prevention.
Learn about malaria, a mosquito-borne infectious disease caused by parasitic protozoans of the genus Plasmodium. Understand how it's transmitted and prevalent in tropical and subtropical regions.
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