viernes, 29 de octubre de 2010
Rapid Diagnostic Tests for Malaria --- Haiti, 2010
October 29, 2010 / 59(42);1372-1373
Plasmodium falciparum malaria is endemic to Haiti and remains a major concern for residents, including displaced persons, and emergency responders in the aftermath of the January 12, 2010 earthquake (1). Microscopy has been the only test approved in the national policy for the diagnosis and management of malaria in Haiti; however, the use of microscopy often has been limited by lack of equipment or trained personnel. In contrast, malaria rapid diagnostic tests (RDTs) require less equipment or training to use. To assist in the timely diagnosis and treatment of malaria in Haiti, the Ministry of Public Health and Population (MSPP), in collaboration with CDC, conducted a field assessment that guided the decision to approve the use of RDTs. This data-driven policy change greatly expands the opportunities for accurate malaria diagnosis across the country, allows for improved clinical management of febrile patients, and will improve the quality of malaria surveillance in Haiti.
The selection of diagnostic tests for malaria for a country's national policy depends on multiple factors including the availability of health facility and laboratory infrastructure, financial resources, skilled personnel, and local epidemiology of the disease. For these reasons, national policies might differ in their recommended first-line diagnostic test. In the United States, both microscopy and RDTs are recommended, and at minimum, either test should be available at health-care facilities for malaria diagnosis; the only approved RDT in the United States, however, is BinaxNOW Malaria (Inverness Medical, Princeton, New Jersey). In addition, polymerase chain reaction can be used for malaria diagnosis and is most useful for species confirmation.
Until now, official MSPP policy for laboratory diagnosis of malaria has been to rely exclusively on microscopy. RDTs had not been incorporated into the MSPP malaria control strategy because of concerns that these newer tools, when compared with microscopy, were not sufficiently sensitive and would be difficult to sustain in some settings in Haiti. After the earthquake, with the acute need for clinical services and malaria diagnostics and the presence of international nongovernmental organizations assisting with the response, MSPP allowed the use of RDTs for 90 days (January 12--April 12, 2010). No specific RDT brands were endorsed for temporary use.
During 2 weeks in April, MSPP and CDC compared the performance of expert microscopy with the performance of two brands of RDTs introduced temporarily in Haiti for malaria diagnosis. Four health facilities were included in the assessment. Of these, two sites where local health workers were trained to use one brand of RDT demonstrated acceptable sensitivity (100% and 84.2%) and specificity (91.4% and 94.0%). The third site, using the other brand of RDT, showed poor sensitivity (51.6%) but adequate specificity (94.4%). Shortly before the assessment, the World Health Organization issued RDT procurement recommendations based on previously published rigorous performance evaluations, and this latter RDT brand was not listed at that time as a preferred test for low transmission settings (2). The fourth site did not submit enough samples for comparison.
The in-country data demonstrated that at least one of the two brands of RDTs could perform adequately in Haiti, and these findings correlated with the published evaluations. Based on this experience, MSPP has adopted use of RDTs as part of the national strategy at the following health facilities: 1) health centers and clinics without microscopy capacity; and 2) departmental hospitals, community referral hospitals, and specialty hospitals during laboratory off-hours or if microscopy is not available. The use of RDTs is not permitted in teaching hospitals because these facilities are required to have microscopy capacity in Haiti.
As of July 2010, three brands of RDTs for the diagnosis of P. falciparum malaria have been approved by MSPP for use in Haiti: First Response Malaria Ag HRP2 (Premier Medical Corporation Ltd., Watchung, New Jersey), CareStart Malaria HRP2 (Pf) (Access Bio, Inc., Monmouth Junction, New Jersey), and SD Bioline Malaria Ag Pf (Standard Diagnostics, Inc., Yongin, Korea). Although in-country data from the RDT field assessment demonstrated that some RDTs could perform comparably to microscopy, the selection of these three brands was based on previously published laboratory evaluations (3,4). The main criterion used by MSPP for the approved RDTs was a detection rate* of ≥97% for P. falciparum at low parasite densities. The RDT that performed with adequate sensitivity in the field assessment had a detection rate exceeding this threshold and was included as one of the approved tests. Clinicians in Haiti, international emergency responders, and health officials should be aware of this change in policy, which now recommends the use of any of these three RDTs for the diagnosis of malaria in the specified health-care settings.
A Existe, MD, N Freeman, MPH, J Boncy, MD, National Public Health Laboratory; R Magloire, MD, Dept of Epidemiology and Laboratory Research; J-F Vely, MD, National Malaria Control Program, Haiti Ministry of Public Health and Population. M Chang, MD, H Bishop, A Macedo de Oliveira, MD, M McMorrow, MD, A Dasilva, PhD, J Barnwell, PhD, L Slutsker, MD, Div of Parasitic Diseases and Malaria, Center for Global Health; D Townes, MD, EIS Officer, CDC.
1. CDC. Malaria acquired in Haiti---2010. MMWR 2010;59:217--9.
2. World Health Organization. Information note on recommended selection criteria for malaria rapid diagnostic tests (RDTs). Geneva, Switzerland: World Health Organization; 2010. Available at http://www.who.int/malaria/diagnosis_treatment/diagnosis/RDT_selection_criteria.pdf Adobe PDF fileExternal Web Site Icon. Accessed October 25, 2010.
3. World Health Organization. Malaria rapid diagnostic test performance: results of WHO product testing of malaria RDTs: round 1 (2008). Geneva, Switzerland: World Health Organization; 2009. Available at http://www.wpro.who.int/sites/rdt/who_rdt_evaluation/call_for_testing.htmExternal Web Site Icon. Accessed October 27, 2010.
4. World Health Organization. Malaria rapid diagnostic test performance: results of WHO product testing of malaria RDTs: round 2 (2009). Geneva, Switzerland: World Health Organization; 2010. Available at http://apps.who.int/tdr/publications/tdr-research-publications/rdt_round2/pdf/rdt_round2.pdf Adobe PDF fileExternal Web Site Icon. Accessed October 25, 2010.
* A sample is considered detected only if all RDTs from two lots read by the first technician, at minimum specified reading time, are positive. Wild type P. falciparum samples at a concentration of 200 parasites/µL were used for laboratory testing.
Rapid Diagnostic Tests for Malaria --- Haiti, 2010