Scott Filler

Malaria surveillance -- United States, 2009

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 regions with ongoing malaria transmission. However, malaria is occasionally acquired by persons who have not traveled out of the country through exposure to infected blood products, congenital transmission, laboratory exposure, or local mosquitoborne transmission. Malaria surveillance in the United States is conducted to provide information on its occurrence (e.g., temporal, geographic, and demographic), guide prevention and treatment recommendations for travelers and patients, and facilitate transmission control measures if locally acquired cases are identified. Period Covered This report summarizes confirmed malaria cases in persons with onset of illness in 2015 and summarizes trends in previous years. Description of System Malaria cases diagnosed by blood film microscopy, polymerase chain reaction, or rapid diagnostic tests are 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), the National Notifiable Diseases Surveillance System (NNDSS), or direct CDC consultations. CDC reference laboratories provide diagnostic assistance and conduct antimalarial drug resistance marker testing on blood samples submitted by health care providers or local or state health departments. This report summarizes data from the integration of all NMSS and NNDSS cases, CDC reference laboratory reports, and CDC clinical consultations. Results CDC received reports of 1,517 confirmed malaria cases, including one congenital case, with an onset of symptoms in 2015 among persons who received their diagnoses in the United States. Although the number of malaria cases diagnosed in the United States has been increasing since the mid-1970s, the number of cases decreased by 208 from 2014 to 2015. Among the regions of acquisition (Africa, West Africa, Asia, Central America, the Caribbean, South America, Oceania, and the Middle East), the only region with significantly fewer imported cases in 2015 compared with 2014 was West Africa (781 versus 969). Plasmodium falciparum, P. vivax, P. ovale, and P. malariae were identified in 67.4%, 11.7%, 4.1%, and 3.1% of cases, respectively. Less than 1% of patients were infected by two species. The infecting species was unreported or undetermined in 12.9% of cases. CDC provided diagnostic assistance for 13.1% of patients with confirmed cases and tested 15.0% of P. falciparum specimens for antimalarial resistance markers. Of the U.S. resident patients who reported purpose of travel, 68.4% were visiting friends or relatives. A lower proportion of U.S. residents with malaria reported taking any chemoprophylaxis in 2015 (26.5%) compared with 2014 (32.5%), and adherence was poor in this group. Among the U.S residents for whom information on chemoprophylaxis use and travel region were known, 95.3% of patients with malaria did not adhere to or did not take a CDC-recommended chemoprophylaxis regimen. Among women with malaria, 32 were pregnant, and none had adhered to chemoprophylaxis. A total of 23 malaria cases occurred among U.S. military personnel in 2015. Three cases of malaria were imported from the approximately 3,000 military personnel deployed to an Ebola-affected country; two of these were not P. falciparum species, and one species was unspecified. Among all reported cases in 2015, 17.1% were classified as severe illnesses and 11 persons died, compared with an average of 6.1 deaths per year during 2000–2014. In 2015, CDC received 153 P. falciparum-positive samples for surveillance of antimalarial resistance markers (although certain loci were untestable for some samples); genetic polymorphisms associated with resistance to pyrimethamine were identified in 132 (86.3%), to sulfadoxine in 112 (73.7%), to chloroquine in 48 (31.4%), to mefloquine in six (4.3%), and to artemisinin in one (<1%), and no sample had resistance to atovaquone. Completion of data elements on the malaria case report form decreased from 2014 to 2015 and remains low, with 24.2% of case report forms missing at least one key element (species, travel history, and resident status). Interpretation The decrease in malaria cases from 2014 to 2015 is associated with a decrease in imported cases from West Africa. This finding might be related to altered or curtailed travel to Ebola-affected countries in in this region. Despite progress in reducing malaria worldwide, the disease remains endemic in many regions, and the use of appropriate prevention measures by travelers is still inadequate. Public Health Actions The best way to prevent malaria is to take chemoprophylaxis medication during travel to a country where malaria is endemic. As demonstrated by the U.S. military during the Ebola response, use of chemoprophylaxis and other protection measures is possible in stressful environments, and this can prevent malaria, especially P. falciparum, even in high transmission areas. Detailed recommendations for preventing malaria are available to the general public at the CDC website (https://www.cdc.gov/malaria/travelers/drugs.html). Malaria infections can be fatal if not diagnosed and treated promptly with antimalarial medications appropriate for the patient’s age and medical history, the likely country of malaria acquisition, and previous use of antimalarial chemoprophylaxis. Health care providers should consult the CDC Guidelines for Treatment of Malaria in the United States and contact the CDC’s Malaria Hotline for case management advice when needed. Malaria treatment recommendations are available online (https://www.cdc.gov/malaria/diagnosis_treatment) and from the Malaria Hotline (770-488-7788 or toll-free at 855-856-4713). Persons submitting malaria case reports (care providers, laboratories, and state and local public health officials) should provide complete information because incomplete reporting compromises case investigations and efforts to prevent infections and examine trends in malaria cases. Compliance with recommended malaria prevention strategies is low among U.S. travelers visiting friends and relatives. Evidence-based prevention strategies that effectively target travelers who are visiting friends and relatives need to be developed and implemented to reduce the numbers of imported malaria cases in the United States. Molecular surveillance of antimalarial drug resistance markers (https://www.cdc.gov/malaria/features/ars.html) has enabled CDC to track, guide treatment, and manage drug resistance in malaria parasites both domestically and internationally. More samples are needed to improve the completeness of antimalarial drug resistance marker analysis; therefore, CDC requests that blood specimens be submitted for all cases diagnosed in the United States.

Improved Malaria Case Management through the Implementation of a Health Facility-Based Sentinel Site Surveillance System in Uganda

Background Heath facility-based sentinel site surveillance has been proposed as a means of monitoring trends in malaria morbidity but may also provide an opportunity to improve malaria case management. Here we described the impact of a sentinel site malaria surveillance system on promoting laboratory testing and rational antimalarial drug use. Methodology/Principal Findings Sentinel site malaria surveillance was established at six health facilities in Uganda between September 2006 and January 2007. Data were collected from all patients presenting to the outpatient departments including demographics, laboratory results, diagnoses, and treatments prescribed. Between the start of surveillance and March 2010, a total 424,701 patients were seen of which 229,375 (54%) were suspected of having malaria. Comparing the first three months with the last three months of surveillance, the proportion of patients with suspected malaria who underwent diagnostic testing increased from 39% to 97% (p<0.001). The proportion of patients with an appropriate decision to prescribe antimalarial therapy (positive test result prescribed, negative test result not prescribed) increased from 64% to 95% (p<0.001). The proportion of patients appropriately prescribed antimalarial therapy who were prescribed the recommended first-line regimen artemether-lumefantrine increased from 48% to 69% (p<0.001). Conclusions/Significance The establishment of a sentinel site malaria surveillance system in Uganda achieved almost universal utilization of diagnostic testing in patients with suspected malaria and appropriate decisions to prescribed antimalarial based on test results. Less success was achieved in promoting prescribing practice for the recommended first-line therapy. This system could provide a model for improving malaria case management in other health facilities in Africa.

Indoor Residual Spraying of Insecticide and Malaria Morbidity in a High Transmission Intensity Area of Uganda

Background Recently the use of indoor residual spraying of insecticide (IRS) has greatly increased in Africa; however, limited data exist on the quantitative impacts of IRS on health outcomes in highly malaria endemic areas. Methodology/Principal Findings Routine data were collected on more than 90,000 patient visits at a single health facility over a 56 month period covering five rounds of IRS using three different insecticides. Temporal associations between the timing of IRS and the probability of a patient referred for microscopy having laboratory confirmed malaria were estimated controlling for seasonality and age. Considering patients less than five years of age there was a modest decrease in the odds of malaria following the 1st round of IRS using DDT (OR = 0.76, p<0.001) and the 2nd round using alpha-cypermethrin (OR = 0.83, p = 0.002). Following rounds 3–5 using bendiocarb there was a much greater decrease in the odds of malaria (ORs 0.34, 0.16, 0.17 respectively, p<0.001 for all comparisons). Overall, the impact of IRS was less pronounced among patients 5 years or older. Conclusions/Significance IRS was associated with a reduction in malaria morbidity in an area of high transmission intensity in Uganda and the benefits appeared to be greatest after switching to a carbamate class of insecticide.

Assessing the Impact of Indoor Residual Spraying on Malaria Morbidity Using a Sentinel Site Surveillance System in Western Uganda

A single round of indoor residual spraying (IRS) using lambda-cyhalothrin was implemented in a district of Uganda with moderate transmission intensity in 2007. Individual patient data were collected from one health facility within the district 8 months before and 16 months after IRS. There was a consistent decrease in the proportion of patients diagnosed with clinical malaria after IRS for patients < 5 and > 5 years of age (52% versus 26%, P < 0.001 and 36% versus 23%, P < 0.001, respectively). There was a large decrease in the proportion of positive blood smears in the first 4 months after IRS for patients < 5 (47% versus 14%, P < 0.001) and > 5 (26% versus 9%, P < 0.001) years of age, but this effect waned over the subsequent 12 months. IRS was effective in reducing malaria morbidity, but this was not sustained beyond 1 year for the proportion of blood smears read as positive.

Assessment of a national monitoring and evaluation system for rapid expansion of antiretroviral treatment in Malawi.

Objectives  Monitoring and evaluation of national antiretroviral therapy (ART) programs is vital, but routine, standardized assessment of national ART patient monitoring systems has not been established. Malawi has undertaken an ambitious ART scale‐up effort, with over 57 000 patients initiated on ART by June 2006. We assessed the national ART monitoring and evaluation system in Malawi to ensure that the response to the epidemic was being monitored efficiently and effectively, and that data collected were useful.

Evaluation of a Comprehensive Refresher Training Program in Malaria Microscopy Covering Four Districts of Uganda

Microscopy remains the gold standard for malaria diagnosis. However, quality microscopy services are severely lacking in most African countries. To improve capacity for malaria microscopy in Uganda, a 3-day refresher training program was conducted in four districts. Training impact was measured through a written examination and evaluation of the quality of blood-slide preparation and accuracy of field microscopy. A total of 184 of 192 (96%) identified laboratory personnel participated in the training. Average test scores improved from 41% to 75% (P < 0.001). A total of 1,079 and 1,190 routinely made thick blood smears were collected before and after the training, respectively. Sensitivity improved from 84% to 95% (P < 0.001), and specificity improved from 87% to 97% (P < 0.001). The proportion of well-prepared blood smears improved from 6% to 75% (P < 0.001). Supplemental training can have a significant impact on the knowledge of staff, accuracy of microscopy, and quality of blood-slide preparation.

Evaluation of reported malaria chemoprophylactic failure among travelers in a US university exchange program, 2002.

BACKGROUND Travelers to malarious areas are at risk of acquiring malaria; however, with chemoprophylaxis and prompt, effective therapy, serious complications of infection are generally preventable. In June 2002, we investigated a report of a cluster of malaria cases among US university staff and students who visited Ghana and were reportedly adherent to appropriate malaria chemoprophylaxis. METHODS We administered a questionnaire to all participants and collected blood specimens for malaria serological examinations from those reporting malaria infection diagnosed by blood smear in Ghana. RESULTS Of the 33 participants, 25 completed the questionnaire. Twenty-four took a Centers for Disease Control and Prevention-recommended chemoprophylactic drug; 14 (56%) of 25 reported complete adherence to therapy. Twenty (80%) of 25 subjects reported symptoms consistent with possible malaria. Six of these persons reported a microscopic diagnosis of malaria and were treated in Ghana. Serological examination for malaria was performed using blood samples obtained from 5 of these participants; the results for all were negative, suggesting that incorrect diagnoses of malaria were made. CONCLUSIONS Misdiagnosis of malaria made while a person is abroad may not only lead to erroneous reports of drug resistance, but it could also result in unnecessary administration of antimalarial treatment. Health care providers and public health authorities must critically evaluate reports of chemoprophylactic failures and disseminate accurate information to travelers.

Validity of Verbal Autopsy Procedures for Determining Malaria Deaths in Different Epidemiological Settings in Uganda

Background Verbal autopsy (VA) procedures can be used to estimate cause of death in settings with inadequate vital registries. However, the sensitivity of VA for determining malaria-specific mortality may be low, and may vary with transmission intensity. We assessed the diagnostic accuracy of VA procedures as compared to hospital medical records for determining cause of death in children under five in three different malaria transmission settings in Uganda, including Tororo (high), Kampala (medium), and Kisoro (low). Methods and Findings Caretakers of children who died in participating hospitals were interviewed using a standardized World Health Organization questionnaire. Medical records from the childs hospitalization were also reviewed. Causes of death based on the VA questionnaires and the medical records were assigned independently by physician reviewers and then compared. A total of 719 cases were included in the final analysis, 67 in Tororo, 600 in Kampala, and 52 in Kisoro. Malaria was classified as the underlying or contributory cause of death by review of medical records in 33 deaths in Tororo, 60 in Kampala, and 0 in Kisoro. The sensitivity of VA procedures for determining malaria deaths in Tororo was 61% (95% CI 44–78%) and 50% in Kampala (95% CI 37–63%). Specificity for determining malaria deaths in Tororo and Kampala was high (>88%), but positive predictive value varied widely, from 83% in Tororo to 34% in Kampala (difference 49%, 95% CI 31–67, p<0.001). The difference between the cause-specific mortality fraction for malaria as determined by VA procedures and medical records was −11% in Tororo, +5% in Kampala, and +14% in Kisoro. Conclusions Our results suggest that these VA methods have an acceptable level of diagnostic accuracy for determining malaria deaths at the population level in high and medium transmission areas, but not in low transmission areas.