Choosing the right anti-malarial drug

Every year, World Malaria Day is commemorated on the 25th of April and recognizes global efforts to control malaria. In honor of this effort, I hope to share some information on malaria for U.S residents and travelers.

Malaria is caused by a parasite called Plasmodium vivax (P.vivax), which is transmitted via the bites of infected mosquitoes. Inside the human liver, the parasites multiply and then infect red blood cells causing symptoms such as headache, fever, and vomiting. Without treatment, malaria can disrupt blood flow to vital body organs and become life threatening. In 2010 an estimated 219 million cases of malaria occurred worldwide and 660,000 people died, most (91%) in the African Region.

According to the CDC; every year, millions of US residents travel to countries where malaria is present. About 1,500 cases of malaria are diagnosed in the United States annually, and most are in returned travelers. Travelers to sub-Saharan Africa especially have the greatest risk of both getting malaria and dying from their infection. Here are some tips for the U.S. traveler:

• Click here to determine if malaria transmission occurs at your destination: For low risk areas, travelers may use mosquito avoidance measures only, and no preventive drugs are needed.
• Be familiar with the symptoms: If you start feeling fever or flu-like illness while traveling in a malaria-risk area or after returning home (for up to 1 year),seek immediate medical attention.
• Purchase your antimalarial drugs before travelling overseas: Counterfeit ,and therefore ineffective drugs, are very common in some countries
• Be aware that you may not be able to give blood for a while: If you have recently travelled to a place where malaria transmission occurs, that is usually an exclusion criterion for blood donation
• No antimalarial drug is 100% protective: Drugs must be combined with mosquito protective measures such as mosquito nets use, insect repellent, long pants and sleeves.
• Check for drug-drug interactions: Anti malarial drugs may interact with you regular medications, so make sure your pharmacist does a check for you.

There are several drugs recommended for the prevention of malaria, and below I have provided some pros and cons of each. Use this as a guide to know which antimalarial drug is right for you:

ATOVAQUONE/PROGUANIL (MALARONE)

• Good for last-minute travelers since drug is usually started 1-2 days before travel
• Dosed daily
• Good choice for shorter trips because you only have to take the medicine for 7 days after traveling rather than 4 weeks
• Well tolerated – side effects uncommon
• Pediatric tablets available

Disadvantages

• Contraindicated in pregnant and breastfeeding women
• Contraindicated in severe renal impairment
• Relatively more expensive (especially for long trips)
• Daily dosing may be inconvenient (especially in children)

CHLOROQUINE

• Convenient weekly dosing (good for long trips)
• Convenient in patients already taking hydroxychloroquine chronically for rheumatologic conditions (no need for additional medications)
• Can be used in all pregnancy trimesters

Disadvantages

• There is high resistance to chloroquine in some countries (also can’t be used in mefloquine resistance)
• May worsen psoriasis
• Needs to be taken for 4 weeks after travel (not ideal for short duration trips)
• Needs to be started 1-2 weeks before travel, therefore not a good choice for last-minute travelers

DOXYCYCLINE

• Daily dosing
• Good for last-minute travelers since drug is usually started 1-2 days before travel
• Least expensive antimalarial drug
• Convenient in patients already taking hydroxychloroquine chronically e.g. for acne prevention (no need for additional medications)
• Can also prevent some additional infections (e.g., Rickettsiae and leptospirosis) and so it may be preferred by people planning to do lots of hiking, camping, and wading and swimming in fresh water

Disadvantages

• Contraindicated in pregnant women and children <8 years old
• Daily dosing may be inconvenient (especially in children)
• Needs to be taken for 4 weeks after travel (not ideal for short duration trips)
• May cause vaginal yeast infections in women prone when taking antibiotics
• Not ideal for people planning on trips with high sun exposure due to its increased risk of sun sensitivity
• Gastrointestinal side-effects of concern to some people

MEFLOQUINE (LARIAM) 

• Convenient weekly dosing (good for long trips)
• Can be used during pregnancy

Disadvantages

• There is high resistance to mefloquine in some countries
• Contraindicated in patients with certain psychiatric conditions or with a seizure disorder
• Not recommended for persons with cardiac conduction abnormalities
• Needs to be started 2 weeks before travel, therefore not a good choice for last-minute travelers
• Needs to be taken for 4 weeks after travel (not ideal for short duration trips)

PRIMAQUINE

• Most effective medicine for preventing P. vivax, therefore good choice for travel to places with > 90% P. vivax
• Good for last-minute travelers since drug is usually started 1-2 days before travel
• Dosed daily
• Good choice for shorter trips because you only have to take the medicine for 7 days after traveling rather than 4 weeks

Disadvantages

• Contraindicated in patients with glucose-6-phosphatase dehydrogenase (G6PD) deficiency or people who have not been tested for G6PD deficiency
• A G6PD test is costly and takes time; however, it only has to be done once. Once a normal G6PD level is verified and documented, the test does not have to be repeated the next time primaquine is considered
• Contraindicated in pregnant women
• Contraindicated in breastfeeding women unless the infant has also been tested for G6PD deficiency
• Daily dosing may be inconvenient (especially in children)
• Gastrointestinal side-effects of concern to some people

Have you used any of these antimalarial drugs? What was your experience?