Malaria surveillance - United States, 2008.

PROBLEM/CONDITION: Malaria in humans is caused by intraerythrocytic protozoa of the genus Plasmodium. These parasites are transmitted by the bite of an infective female Anopheles species mosquito. The majority of malaria infections in the United States occur among persons who have traveled to areas with ongoing malaria transmission. In the United States, cases can occur through exposure to infected blood products, congenital transmission, or local mosquitoborne transmission. Malaria surveillance is conducted to identify episodes of local transmission and to guide prevention recommendations for travelers. PERIOD COVERED: This report summarizes cases in patients with onset of illness in 2008 and summarizes trends during previous years. DESCRIPTION OF SYSTEM: Malaria cases diagnosed by blood film, polymerase chain reaction, or rapid diagnostic tests are mandated to be reported to local and state health departments by health-care providers or laboratory staff members. Case investigations are conducted by local and state health departments, and reports are transmitted to CDC through the National Malaria Surveillance System (NMSS), National Notifiable Diseases Surveillance System (NNDSS), and direct CDC consultations. Data from these reporting systems are the basis for this report. RESULTS: CDC received reports of 1,298 cases of malaria with an onset of symptoms in 2008 among patients in the United States, a decrease of 13.8% from the 1,505 cases reported for 2007 (p<0.001). These cases included one cryptic [corrected] case, one congenital case, and two fatal cases. Plasmodium falciparum, P. vivax, P. malariae, and P. ovale were identified in 40.6%, 14.6%, 1.5%, and 1.4% of cases, respectively. The first documented case of simian malaria, P. knowlesi, was reported in a U.S. traveler. Eight (0.6%) of the 1,298 patients were infected by two or more species. The infecting species was unreported or undetermined in 41.2% of cases. Based on estimated volume of travel from the World Tourism Organization, the highest estimated relative case rates of malaria among travelers occurred among those returning from countries in West Africa. A total of 508 U.S. civilians acquired malaria abroad; among the 480 civilians for whom chemoprophylaxis information was known, 344 (71.7%) reported that they had not followed a chemoprophylactic drug regimen recommended by CDC for the area to which they had traveled. Fourteen cases were reported in pregnant women, among whom none adhered to a complete prevention drug regimen. INTERPRETATION: A significant decrease in the number of malaria cases occurred from 2007 to 2008. No change occurred in the proportions of cases caused by the various Plasmodium species. U.S. civilians traveling to countries in West Africa had the highest estimated relative case rates. In the majority of reported cases, U.S. civilians who acquired malaria abroad had not adhered to a chemoprophylaxis regimen that was appropriate for the country in which they acquired the infection. PUBLIC HEALTH ACTIONS: Persons traveling to an area in which malaria is endemic should take steps to prevent malaria, which might include taking one of the recommended chemoprophylaxis regimens appropriate for the region of travel and using personal protection measures to prevent mosquito bites. Any person who has been to a malarious area and who subsequently develops a fever or influenza-like symptoms should seek medical care immediately and report their travel history to the clinician; investigation should always include blood-film tests for malaria with results available immediately. Malaria infections can be fatal if not diagnosed and treated promptly. Malaria prevention recommendations are available from CDC online (http://wwwn.cdc.gov/travel/contentDiseases.aspx#malaria) or by calling the Malaria Hotline (telephone 770-488-7788). Malaria treatment recommendations can be obtained from CDC online (http://www.cdc.gov/malaria/diagnosis_treatment/treatment.htm) or by calling the Malaria Hotline.

Pretravel health preparation among US residents traveling to India to VFRs: importance of ethnicity in defining VFRs.

BACKGROUND: International travelers visiting friends and relatives (VFRs) in lower income countries experience high rates of travel-related infections. We examined demographic characteristics and pretravel preparation practices among US residents traveling to India to determine factors that may contribute to higher infection rates and that would allow for improved prevention strategies. METHODS: A cross-sectional study was conducted among US residents traveling to India in departure areas for flights to India at three US international airports during August 2005. Eligible travelers were US residents going to India who were English speaking and >or=18 years. Self-administered questionnaires were used to assess knowledge of and compliance with pretravel health recommendations. RESULTS: Of 1,574 eligible travelers, 1,302 (83%) participated; 60% were male and the median age was 37. Eighty-five percent were of South Asian/Indian ethnicity and 76% reported VFR as the primary reason for travel. More than 90% of VFRs had at least a college education and only 6% cited financial barriers as reasons for not obtaining travel health services. VFRs were less likely than non-VFR travelers to seek pretravel health advice, to be protected against hepatitis A or typhoid fever, and less likely to be taking appropriate antimalarial chemoprophylaxis. However, when stratified by ethnicity, travelers of South Asian ethnicity were less likely than other travelers to adhere to pretravel health recommendations, regardless of VFR status. CONCLUSIONS: Similar to previous studies, VFR status was associated with pretravel health practices that leave travelers at risk for important infectious diseases. This association differed by ethnicity, which may also be an important marker of nonadherence to pretravel health recommendations. These findings have important implications for identifying at-risk travelers and properly targeting prevention messages.

Malaria surveillance--United States, 2006.

PROBLEM/CONDITION: Malaria in humans is caused by intraerythrocytic protozoa of the genus Plasmodium (i.e., P. falciparum, P. vivax, P. ovale, and P. malariae). These parasites are transmitted by the bite of an infective female Anopheles species mosquito. The majority of malaria infections in the United States occur among persons who have traveled to areas with ongoing malaria transmission. In the United States, cases can occur through exposure to infected blood products, congenital transmission, or local mosquitoborne transmission. Malaria surveillance is conducted to identify episodes of local transmission and to guide prevention recommendations for travelers. PERIOD COVERED: This report summarizes cases in persons with onset of illness in 2006 and summarizes trends during previous years. DESCRIPTION OF SYSTEM: Malaria cases confirmed by blood film or polymerase chain reaction (PCR) are mandated to be reported to local and state health departments by health-care providers or laboratory staff members. Case investigations are conducted by local and state health departments, and reports are transmitted to CDC through the National Malaria Surveillance System (NMSS), National Notifiable Diseases Surveillance System (NNDSS), and direct CDC consultations. Data from these reporting systems serve as the basis for this report. RESULTS: CDC received reports of 1,564 cases of malaria among persons in the United States with onset of symptoms in 2006, six of which were fatal. This is an increase of 2.4% from the 1,528 cases reported for 2005. P. falciparum, P. vivax, P. malariae, and P. ovale were identified in 39.2%, 17.6%, 2.9%, and 3.0% of cases, respectively. Ten patients (0.6%) were infected by two or more species. The infecting species was unreported or undetermined in 36.6% of cases. Compared with 2005, the largest increases in cases were from Asia (16.0%). Based on estimated volume of travel, the highest estimated relative case rates of malaria among travelers occurred among those returning from West Africa. Of 602 U.S. civilians who acquired malaria abroad and for whom chemoprophylaxis information was known, 405 (67.3%) reported that they had not followed a chemoprophylactic drug regimen recommended by CDC for the area to which they had traveled. Seventeen cases were reported in pregnant women, among whom only one reported taking chemoprophylaxis precautions. Six deaths were reported; five of the persons were infected with P. falciparum and one with P. malariae. INTERPRETATION: Despite the 2.4% increase in cases from 2005 to 2006, the numbers of malaria cases remained relatively stable during 2001--2006. No change was detected in the proportion of cases by species responsible for infection. U.S. civilians traveling to West Africa had the highest estimated relative case rates. In the majority of reported cases, U.S. civilians who acquired infection abroad had not adhered to a chemoprophylaxis regimen that was appropriate for the country in which they acquired malaria. PUBLIC HEALTH ACTIONS: Additional investigations were conducted of the six fatal cases that occurred in the United States. Persons traveling to a malarious area should take one of the recommended chemoprophylaxis regimens appropriate for the region of travel and use personal protection measures to prevent mosquito bites. Any person who has been to a malarious area and who subsequently has a fever or influenza-like symptoms should seek medical care immediately and report their travel history to the clinician; investigation should always include blood-film tests for malaria, with results made available immediately. Malaria infections can be fatal if not diagnosed and treated promptly. CDC recommendations concerning malaria prevention are available at http://wwwn. cdc.gov/travel/contentdiseases.aspx#malaria or by calling the CDC Malaria Branch on weekdays (telephone: 770-488-7788; Monday--Friday, 8:00 A.M.--4:30 P.M. EST); during evenings, weekends, and holidays, call the CDC Director's Emergency Operations Center (telephone: 770-488-7100), and ask to page the person on call for the Malaria Branch. Recommendations concerning malaria treatment are available at http://www.cdc.gov/malaria/diagnosis_treatment/treatment.htm or by calling the CDC Malaria Hotline.

Health communication during SARS.

During the severe acute respiratory syndrome (SARS) outbreak, electronic media made it possible to disseminate prevention messages rapidly. The Centers for Disease Control and Prevention's Travelers' Health Web site was frequently visited in the first half of 2003; more than 2.6 million visits were made to travel alerts, advisories, and other SARS-related documents.