Microbiology
Summary
Chloroquine, an oral antimalarial derived from the Cinchona tree, was historically the primary drug used to treat malaria. This drug operates by accumulating in the parasite's food vacuole, where it prevents heme crystallization, which is toxic to the parasite. However, its widespread use has led to the emergence of chloroquine-resistant strains of malaria, most notably P. falciparum. This resistance is due to mutations in the genes that code for chloroquine transport proteins, which prevent the drug from accumulating in its target area.
In response to growing resistance, several alternative treatments have been developed. Artemisinins have become the first-line treatment for resistant malaria. Another effective drug is atovaquone-proguanil, and there's also a combination therapy involving tetracyclines and quinine; however, quinine can lead to cinchonism, which presents symptoms like tinnitus, hearing loss, and altered mental status. Another drug, mefloquine, although effective, has seen limited use due to its neuropsychiatric side effects. For strains like P. vivax and P. ovale that possess dormant liver stages, primaquine and tafenoquine can be effective. However, primaquine shouldn't be administered to those with G6PD deficiency due to the risk of hemolysis. For severe cases of malaria, IV artesunate is recommended. Prevention strategies include using treated bed nets and taking chemoprophylaxis when traveling to high-risk areas. After traveling, it's important to continue certain prophylactic drugs for 4 weeks to ensure complete protection.
Lesson Outline
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FAQs
The standard treatments for Plasmodium infection include artemisinin combination therapy (ACT) which is the first line treatment for uncomplicated malaria. Other antimalarial drugs include atovaquone-proguanil, tetracycline plus quinine, and mefloquine. In cases of Plasmodium vivax and Plasmodium ovale infections, primaquine targets the dormant liver stages (hypnozoites) and is used to avoid relapse.
Malaria prophylaxis works by taking antimalarial drugs before, during, and after traveling to areas where malaria is common. The goal is to prevent the malaria parasite from maturing and multiplying in the liver and blood cells, thus preventing the onset of the disease.
In the case of chloroquine-resistant malaria, alternatives like artemisinin combination therapy (ACT), atovaquone-proguanil, and tetracycline plus quinine may be used. The selection of treatment depends on the specific strain of Plasmodium and the geographical area of infection.
The common side effects of mefloquine include dizziness, difficulty sleeping, and unusual dreams. In some cases, severe side effects such as depression, anxiety, hallucinations, and rare cases of severe psychiatric symptoms can occur. It's important to consult a healthcare provider immediately if any severe side effects are experienced.
The commonly observed symptoms of malaria typically begin 10-15 days after the mosquito bite and include fever, fatigue, vomiting, and headaches. In severe cases, it can cause yellow skin, seizures, coma, or death.
