Malaria

Introduction

Malaria is a disease which is transmitted to humans by the female Anopheles mosquito. (There are 430 known species of Anopheles mosquitoes - only 30-50 of those are responsible for malaria.) Unlike many of the illnesses affecting travelers, Malaria is caused by a parasite (Plasmodium) rather than a virus or strain of bacteria. It is preventable.

There are four species of the Plasmodium parasite that cause malaria in humans: P. malariae, P. ovale, P. vivax, and P. falciparum. P. vivax and P. falciparum are the two most common species and P. falciparum is by far the most fatal.

• P. malariae - causes long term infections and can remain asymptomatic for years if untreated.
• P. ovale and P. vivax - both cycle between dormant and active stages. During dormancy, the parasite is harbored in the liver, reactivating itself periodically over months or even years following infection.
• P. falciparum - causes the most severe symptoms and is considered by WHO and the CDC to be responsible for the majority of malaria-related deaths, especially in Africa.

Malaria is present in large parts of southern and southeast Asia, Sub-Saharan Africa, Central and South America, the Caribbean, the Middle East and parts of Eastern Europe and the Pacific. Temperature and rainfall play major roles in the distribution of malaria and whether an area is considered endemic or intermittently endemic. Those two factors are key in the mosquito's life cycle and directly affect the spread of the disease. ^{[1] [2] [3]}

Prevention

General Information

As with most travel-related illnesses, you are the first line of defense. Both the World Health Organization (WHO)^[4] and the Centers for Disease Control and Prevention (CDC)^[5] have regional/country-specific recommendations and maps for assessing the risk factors.

Other preventative measures include:

• Administration of oral anti-malarial medications.
• When outdoors, use insect repellent containing 50% DEET for adults and 10% DEET for children. Follow the directions on the package.
• Many mosquitoes are most active at dusk and dawn. Be sure to use insect repellent and wear long sleeves and pants at these times or consider staying indoors during these hours.
• Avoid wearing dark coloured clothing.
• Avoid wearing perfume/cologne and scented cosmetics.
• Use of mosquito netting during sleep periods.

Anti-Malarial Medications

Many physicians and traveler's health clinics will prescribe a broad-spectrum medication regardless of destination and/or risk factors. These medications are usually the most expensive as well. Researching the destination and assessing the risk factors prior to speaking with a physician will aid both of you in deciding which anti-malarial is best suited for your travel plans. Some medications can interfere with others you may be taking and some do have negative side effects in certain circumstances.

It should also be noted that anti-malarial medications do not prevent the parasite from entering the body but do prevent or suppress the symptoms caused by the parasite. Some physicians may refer to these medications as malaria suppressor drugs rather than anti-malarials. Anyone taking oral prophylactic measures will begin the regimen prior to travel, continue treatment while in a risk area and end the treatment one or more weeks after leaving the area.

The following is a list of the most frequently prescribed anti-malarial medications for the recreational traveler, whether it is two weeks in paradise or a two year round-the-world adventure. It should be noted other medications are available but are normally only prescribed for those who can not use and/or tolerate those listed below.

Malarone™ (Atovaquone/proguanil combination)
Malarone™ is a combination of two drugs that have been used seperately as anti-malarials for several years. Independently, both medications have few side effects, are tolerated well and long-term use information is available. The use of these two drugs in combination is relatively new. Side effects are still low and well-tolerated but long-term use (>3-6 months) information is not yet available. Side effects do include stomach pain, nausea, vomiting, and headache. Vivid dreams have also been associated with Malarone but subside once the drug is discontinued. People suffering from decreased renal function, children under 5kg, women nursing children under 5kg, pregnant women and those allergic to either drug should not take Malarone™. Malarone™ is expensive when compared to other anti-malarial medications. It should be noted that Malarone™ is not available as an "over-the-counter" (OTC) medication anywhere in the world and requires a prescription for purchase. Any and all OTC versions available should be considered as counterfeit medications and avoided.

• Malarone™ is taken once daily, starting 1-2 days prior to travel, continued for the duration of the travel time and ending 7 days after leaving the malarial area.^[6]

Aralen™ (Chloroquine phosphate)
Chloroquine belongs to the family of quinine compounds with quinine being the first to be used against malaria in India/Africa. It is prescribed for use in Mexico, Hispaniola, parts of Central America, the Middle East and Eastern Europe. It is not recommended for use in South America or Sub-Saharan Africa as chloroquine-resistant malaria is endemic/intermittently endemic in these areas. Chroloquine has few side effects, is well tolerated and long-term use inforamtion is available. Side effects can include nausea, vomiting, headache, dizziness, blurred vision and itching. Chloroquine may increase the symptoms in those suffering from psoriasis. It should not be taken by people who are allergic. Chloroquine is inexpensive when compared to other medications. Aralen™ is available in it's generic form (chloroquine) in most areas and, in certain countries, available as an OTC.

• Chloroquine is taken once weekly, starting 1-2 weeks prior to travel, continued for the duration of the travel time and ending 4 weeks after leaving the malarial area. The medication should be taken on the same day of every treatment week.^[6]

Plaquenil™ (Hydroxychloroquine sulfate)
Plaquenil™ is prescribed as an alternative to chloroquine but it's effectiveness is not as well documented. The side effects are the same with the addition of sleeplessness.

• Plaquenil™ is taken once weekly, starting 1-2 weeks prior to travel, continued for the duration of the travel time and ending 4 weeks after leaving the malarial area. The medication should be taken on the same day of every treatment week.^[6]

Lariam™ (Mefloquine)
Lariam™ is the most frequently-debated anti-malarial in reference to recreational travel usage. It belongs to the quinine family of medications (which also includes Chloroquine and Hydroxychlorquine, among others). Of the quinine compounds, mefloquine is the most effective against the most serious type fo malaria - P. falciparum because it remains in the body for a much longer period of time, comparatively. The majority of mefloquine's long-term use information is based upon it's use in military situations. Mild side effects include nausea, headache, dizziness, sleep difficulty, impaired vision, anxiety and vivid dreams. More serious side effects can be seizures, depression and psycho-neurological problems. Due to the slower elimination time (from the body), side effects may continue for weeks or months after discontinuation of treatment. It has been reported that women experience more severe side effects than men. People suffering from or who have a recent history of depression should not take this medication. Those with a history of psychosis, anxiety, schizophrenia, seizures, cardiac abnormalities (such as irregular heartbeat) or are allergic should also refrain from taking Lariam™. Lariam™ is available in it's generic form (mefloquine) in some areas and can be purchased as an OTC in some countries.

• Larium™ is taken once weekly, starting 1-2 weeks prior to travel, continued for the duration of the travel time and ending 4 weeks after leaving the malarial area. The medication should be taken on the same day of every treatment week.^[6][7]

Doxycycline
Doxycycline belongs to the tetracycline family of antibiotics. It can be used as an anti-malarial in all areas. Doxycycline has few side effects, is well tolerated and long-term use information is available. When used as prophylaxis, the dosage is very low (100mg/day) and can be taken for as long as two years without interruption. It does not create bacterial resistance if antibiotic treatment is required for wounds or other illnesses. Side effects include nausea, stomach pain and possible sensitivity to the sun (sunburns more quickly). Take this medication at least one hour before bedtime to avoid reflux into the esphagus (heartburn). Some women may develop vaginal yeast infections with long-term use. Women taking oral contraceptives (OC) are advised to use additional forms of birth control (condoms, diaphragms, etc.) while also taking doxycycline as this medication can decrease the effectiveness of the OCs. It has not been proven that doxycycline renders OCs 100% ineffective. Pregnant women, children under age 8 and those allergic to tetracycline compounds should not take this medication. Doxycycline is the generic term for this medication and it is available in many countries as an OTC.

• Doxycycline is taken once daily, starting 1-2 days prior to travel, continued for the duration of the travel time and ending 4 weeks after leaving the malarial area.^[6]

Symptoms and Treatment

Symptoms

The timeline for the appearance of symptoms is species-dependent. Commonly, symptoms will begin 10-14 days following infection though some forms may not appear for 2 months or more. They will begin with low grade fever and flu-like symptoms with intermittent bouts of chills and high fever. These symptoms will cycle every 1-3 days though there can be days or weeks between cycles. If undiagnosed or left untreated, headache, nausea, vomiting and yellowing of the skin and mucous membrane (jaundice) will possibly follow.

Malaria is one of the most commonly misdiagnosed diseases affecting travelers. It resembles influenza and the cyclic nature of the symptoms allows patients to think they have recovered (from the flu), only to relapse some time later. Blood tests are required for an accurate diagnosis of malaria. If you think you may have the flu but have recently visited a malarial area, seek medical attention immediately. This holds true even for persons who have taken anti-malarial medications during their travel time. ^{[8] [9]}

Treatment

The treatment for malaria will be dependent upon the type, severity and patient's age. Malarone, Quinine, Chorloquine, Mefloquine, Hydroxychloroquine, Doxycycline, Sulfadoxine/pyrimethamine (Fansidar) are all medications used for specific treatments. All will be given at higher dosages than for prophylaxis. Again, diagnosis is key to receiving the correct treatment for the type of infection. Primaquine may also be used in the treament of the P. ovale and P. vivax (dormant liver forms) to prevent relapses. Pregnant women and those with G6PD (glucose-6-phosphate dehydrogenase) deficiency can not take Primaquine. Testing for the deficiency will be performed prior to treatment with this medication. Artemisinin derivatives are also used in some countries but have not been approved for general use in the United States. ^{[10] [11]}