The growing popularity of travel to...

The growing popularity of travel to tropical locales is placing an increasing number of travelers at risk for acquiring malaria. In 1998 the World Health Organization (WHO) indicated that there were more than 270 million cases of malaria worldwide, with more than 1 million deaths caused at the disease. (1,2) In the United States, approximately 1500 cases of malaria are reported annually to the Center for Disease curb and Prevention (CDC). (3)

The evolving pattern of put drugs into resistance in malaria parasites and changes in recommendations for chemoprophylaxis not absent a challenge to physicians who advise patients about preventing this disease. Improving adherence to use of antimosquito measures and antimalarial medications could obstruct many cases of malaria. This article provides an approach to malaria prevention in travelers. It reviews [i]clavis[/i] risk factors for malaria acquisition, measures to debar mosquito bites, and drugs approved for chemoprophylaxis.

Life round of years of Plasmodium

To better appreciate the classifications of malaria prevention, it is necessary to understand the parasite's life round of years Malaria is transmitted through the bite of an infected female Anopheles mosquito and is caused by the agency of infection with one of four species of the protozoa Plasmodium (Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, and Plasmodium ovale). (45)

When an infected mosquito takes a relations meal during its feeding period between dusk and dawn, it injects sporozoites of Plasmodium from its salivary glands into the bloodstream of the army The sporozoites circulate to the liver and invade hepatocytes, where they divide to form tissue schizonts and then merozoites, which escape into the bloodstream. Merozoites invade erythrocyte differentiate into trophozoites, and divide to become posterity schizonts. These then mature into merozoites which, when released from r lonely dwellings can continue the cycle in the blood

A proportion of the sporozoites of P vivax and P ovale disentangle into dormant forms within the liver, called hypnozoites, and these can activate month to years later to release more merozoites into the bloodstream, causing a symptomatic relapse. The life period is completed when merozoites differentiate into sexual forms called gametocytes. The female Anopheles mosquito ingests gametocytes during a relations meal, and sexual stages come in the development of sporozoites that can be transmitted to the nearest susceptible human host.

Approach to Malaria Prevention

The risk of malaria can be reduc according to regular use of measures that limit contact with mosquitoes and from strict adherence to chemoprophylaxis. (6) To help travelers adhere to these recommendations, physicians must provide concluded pre-travel advice. Even a brief prospect in an endemic area offers the unprotected traveler at risk. Because no preventive regimen is completely effective, travelers also should know to try to find medical attention immediately should they become febrile during or after their trip.

The approach to malaria prevention should incorporate the following principles:

* Assess the risk of malaria infection upon the basis of the patient's itinerary.

* Discuss the available orders of reducing contact with Anopheles mosquitoes.

* Identify the most numerous appropriate antimalarial agents for chemoprophylaxis.

* Alert the traveler to try to find early diagnosis and treatment if excitement develops during or after travel.

These principles provide a framework for the physician to chase when counseling patients about malaria prevention during pre-travel office visits. Figure 1 illustrates an algorithmic approach to the prevention of malaria in travelers.

[FIGURE 1 OMITTED]

Assessing the Risk of Malaria

Assessing malarial risk requires a detailed knowledge of a patient's travel itinerary and accommodations. The risk that a traveler will become infected hangs on the overall rate of malaria transmission in the geographic area to be visited and forward the extent of the patient's contact with infected mosquitoes. (7) Transmission rates vary greatly from region to region, on the same level within the same country. In countries where the overall risk is relatively depressed there may be foci of intense transmission.

The assessment of risk of malaria infection hangs on several other considerations. Because malaria transmission frequently follows stringent seasonal patterns linked to rainfall, the timing of the trip may influence the risk. (8) The elevation of the destination also is important because malaria transmission is rare above 2000 m (6561 feet) (9) Finally, because the Anopheles mosquito nourishs from dusk to dawn, the risk of transmission is influenced from a traveler's nighttime activities and accommodations.

Regularly updated maps identifying malaria risk areas and times are available from several sources (Table 1) (10) and can be valuable tools in counseling patients. (11) Details about risk within countries may be obtained from Web sites operated by dint of the CDC (www.cdc.gov/travel) and the WHO (www.who.int/ith).