Malaria [edit]
Description:
Malaria blows up babies.
Malaria in humans is caused by one of four protozoan species of the genus Plasmodium: P. falciparum, P. vivax, P. ovale, or P. malariae. All species are transmitted by the bite of an infected female Anopheles mosquito. Occasionally, transmission occurs by blood transfusion or congenitally from mother to fetus. Although malaria can be a fatal disease, illness and death from malaria are largely preventable.
Occurence
Malaria is a major international public health problem, causing 300–500 million infections worldwide and approximately 1 million deaths annually. Information about malaria risk in specific countries (Yellow Fever Vaccine Requirements and Information on Malaria Risk and Prophylaxis, by Country) is derived from various sources, including the World Health Organization. The information presented herein was accurate at the time of publication; however, factors that can vary from year to year, such as local weather conditions, mosquito vector density, and prevalence of infection, can have a marked effect on local malaria transmission patterns. Updated information may be found on the CDC Travelers’ Health website: http://www.cdc.gov/travel.
Malaria transmission occurs in large areas of Central and South America, Hispaniola, Africa, Asia (including the Indian Subcontinent, Southeast Asia, and the Middle East), Eastern Europe, and the South Pacific).
The estimated risk for a traveler’s acquiring malaria differs markedly from area to area. This variability is a function of the intensity of transmission within the various regions and of the itinerary and time and type of travel. From 1985 through 2001, 10,100 cases of malaria among U.S. civilians were reported to CDC. Of these, 5,849 (58%) were acquired in sub-Saharan Africa; 1,862 (18%) in Asia; 1,634 (16%) in the Caribbean and Central or South America; and 755 (7%) in other parts of the world. During this period, 70 fatal malaria infections occurred among U.S. civilians; 66 (94%) were caused by P. falciparum, of which 47 (71%) were acquired in sub-Saharan Africa.
Thus, most imported P. falciparum malaria among American travelers was acquired in Africa south of the Sahara, even though only 483,000 U.S. residents traveled to countries in that region in 2000. In contrast, that year 27 million U.S. residents traveled from the United States to other countries where malaria is endemic (including 19 million travelers to Mexico). This disparity in the risk for acquiring malaria reflects the fact that the predominant species of malaria transmitted in sub-Saharan Africa is P. falciparum, that malaria transmission is generally higher in Africa than in other parts of the world, and that malaria is often transmitted in urban areas as well as rural areas in sub-Saharan Africa. In contrast, malaria transmission is generally lower in Asia and South America, a larger proportion of the malaria is P. vivax, and most urban areas do not have malaria transmission.
Estimating the risk for infection for various types of travelers is difficult and can be substantially different even for persons who travel or reside temporarily in the same general areas within a country. For example, travelers staying in air-conditioned hotels may be at lower risk than backpackers or adventure travelers. Similarly, long-term residents living in screened and air-conditioned housing are less likely to be exposed than are persons living without such amenities, such as Peace Corps volunteers.
Persons who have been in a malaria risk area, either during daytime or nighttime hours, are not allowed to donate blood for a period of time after returning from the malarious area. Persons who are residents of nonmalarious countries are not allowed to donate blood for 1 year after they have returned from a malarious area. Persons who are residents of malarious countries are not allowed to donate blood for 3 years after leaving a malarious area. Persons who have had malaria are not allowed to donate blood for 3 years after treatment for malaria.
Clinical presentation
Malaria is characterized by fever and influenzalike symptoms, including chills, headache, myalgias, and malaise; these symptoms can occur at intervals. Malaria may be associated with anemia and jaundice, and P. falciparum infections can cause seizures, mental confusion, kidney failure, coma, and death. Malaria symptoms can develop as early as 6 days after initial exposure in a malaria-endemic area and as late as several months after departure from a malarious area, after chemoprophylaxis has been terminated.
Prevention
No vaccine is currently available. Taking an appropriate drug regimen and using antimosquito measures will help prevent malaria. Travelers should be informed that, regardless of methods employed, they are still at risk for contracting malaria.
Personal Protection Measures
Because of the nocturnal feeding habits of Anopheles mosquitoes, malaria transmission occurs primarily between dusk and dawn. Travelers should be advised to take protective measures to reduce contact with mosquitoes, especially during these hours. Such measures include remaining in well-screened areas, using mosquito nets, and wearing clothes that cover most of the body. Additionally, travelers should be advised to purchase insect repellent for use on exposed skin. The most effective repellent against a wide range of vectors is DEET (N,N-diethylmetatoluamide), an ingredient in many commercially available insect repellents. The actual concentration of DEET varies widely among repellents. DEET formulations as high as 50% are recommended for both adults and children >2 months of age. (See Protection against Mosquitoes and Other Arthropod Vectors.)
Travelers not staying in well-screened or air-conditioned rooms should be advised to use a pyrethroid-containing flying-insect spray in living and sleeping areas during evening and nighttime hours. They should take additional precautions, including sleeping under insecticide-treated bed nets. In the United States, permethrin (Permanone) is available as a liquid or spray. Overseas, either permethrin or another insecticide, deltamethrin, is available and may be sprayed on bed nets and clothing for additional protection against mosquitoes. Bed nets are more effective if they are treated with permethrin or deltamethrin insecticide; bed nets may be purchased that have already been treated with insecticide.
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Chemoprophylaxis
Chemoprophylaxis is a broad term comprising multiple strategies for the prevention of malaria by using medications. Primary prophylaxis is the strategy that uses medications prior to, during, and after the exposure period to prevent the initial infection. Terminal prophylaxis is the strategy that uses medications toward the end of the exposure period (or immediately thereafter) to prevent relapses or delayed-onset clinical presentations of malaria caused by P. vivax or P. ovale.
In choosing an appropriate chemoprophylactic regimen before travel, the traveler and the health-care provider should consider several factors. The travel itinerary should be reviewed in detail and compared with the information on areas of risk in a given country (Yellow Fever Vaccine Requirements and Information on Malaria Risk and Prophylaxis, by Country) to determine whether the traveler will actually be at risk for acquiring malaria. Whether the traveler will be at risk for acquiring drug-resistant P. falciparum malaria should also be determined. Resistance to antimalarial drugs has developed in many regions of the world. Health-care providers should consult the latest information on resistance patterns before prescribing prophylaxis for their patients. (See section "Malaria Hotline" below for details about accessing this information from CDC.)
The resistance of P. falciparum to chloroquine has been confirmed in all areas with P. falciparum malaria except the Dominican Republic, Haiti, Central America west of the former Panama Canal Zone, Egypt, and some countries in the Middle East. In addition, resistance to Fansidar is widespread in the Amazon River Basin area of South America, much of Southeast Asia, other parts of Asia, and, increasingly, in large parts of Africa. Resistance to mefloquine has been confirmed on the borders of Thailand with Burma (Myanmar) and Cambodia, in the western provinces of Cambodia, and in the eastern states of Burma (Myanmar).
Tolerability
Malaria chemoprophylaxis with mefloquine or chloroquine should begin 1–2 weeks before travel to malarious areas; prophylaxis with doxycycline and atovaquone/proguanil can begin 1–2 days before travel. Beginning the drug before travel allows the antimalarial to be in the blood before exposure to the malaria parasite. Chemoprophylaxis can be started earlier if there are particular concerns about tolerating one of the medications. Starting the medication 3–4 weeks in advance allows potential adverse events to occur prior to travel. Should unacceptable side effects develop, there would be a greater window of opportunity to change the medication before the traveler’s departure.
The drugs used for antimalarial chemoprophylaxis are generally well tolerated. However, side effects can occur. Minor side effects usually do not require stopping the drug. Travelers who have serious side effects should see a health-care provider. See the section below on “Adverse Reactions and Contraindications” for more detail on safety and tolerability of the drugs used for malaria prevention. In addition, the health-care provider should establish whether the traveler has previously experienced an allergic or other reaction to one of the antimalarial drugs of choice and whether medical care will be readily accessible during travel.
General Recommendations for Primary Prophylaxis
Chemoprophylaxis should continue during travel in the malarious areas and after leaving the malarious areas (4 weeks after travel for chloroquine, mefloquine, and doxycycline, and 7 days after travel for atovaquone/proguanil). Drugs with longer half-lives, which are taken weekly, offer the advantage of a wider margin of error if the traveler is late with a dose than drugs with short half-lives, which are taken daily. For example, if a traveler is 1–2 days late with a weekly drug, prophylactic blood levels can remain adequate; if the traveler is 1–2 days late with a daily drug, protective blood levels are less likely to be maintained.
Treatment
Specific treatment with antimalarial drugs is available. Travelers should be advised that malaria can be treated effectively early in the course of the disease but that delay of appropriate therapy can have serious or even fatal consequences. Travelers who have symptoms of malaria should be advised to seek prompt medical evaluation, including thick and thin blood smears, as soon as possible. If possible, it is advisable to consult with a provider with specialized travel/tropical medicine expertise or with an infectious disease physician.
Self-Treatment
CDC recommends the use of malaria prophylaxis for travel to malarious areas. However, travelers who elect not to take prophylaxis, who do not choose an optimal drug regimen (e.g., chloroquine in an area with chloroquine-resistant P. falciparum) or who require a less than optimal drug regimen are at greater risk for acquiring malaria and needing prompt treatment. Long-term travelers who are taking effective prophylaxis but who will be in very remote areas may decide, in consultation with their health-care provider, to take along a dose of antimalarial medication for self-treatment. Travelers should be advised to take their presumptive self-treatment promptly if they have a fever, chills, or other influenzalike illness and if professional medical care is not available within 24 hours. Travelers should be advised that this self-treatment of a possible malarial infection is only a temporary measure and that prompt medical evaluation is imperative.
Recommendations for Presumptive Self-Treatment
Atovaquone/proguanil may be used for presumptive self-treatment for travelers NOT taking atovaquone/proguanil for prophylaxis. The CDC Malaria Epidemiology Branch (Malaria Hotline 770-488-7788) can provide consultation to health-care providers on other potential options for self-treatment if atovaquone/proguanil cannot be used.
Destinations in Sao Tome and Principe
