Serological markers for monitoring historical changes in malaria transmission intensity in a highly endemic region of Western Kenya, 1994-2009.

BACKGROUND: Monitoring local malaria transmission intensity is essential for planning evidence-based control strategies and evaluating their impact over time. Anti-malarial antibodies provide information on cumulative exposure and have proven useful, in areas where transmission has dropped to low sustained levels, for retrospectively reconstructing the timing and magnitude of transmission reduction. It is unclear whether serological markers are also informative in high transmission settings, where interventions may reduce transmission, but to a level where considerable exposure continues. METHODS: This study was conducted through ongoing KEMRI and CDC collaboration. Asembo, in Western Kenya, is an area where intense malaria transmission was drastically reduced during a 1997-1999 community-randomized, controlled insecticide-treated net (ITN) trial. Two approaches were taken to reconstruct malaria transmission history during the period from 1994 to 2009. First, point measurements were calculated for seroprevalence, mean antibody titre, and seroconversion rate (SCR) against three Plasmodium falciparum antigens (AMA-1, MSP-119, and CSP) at five time points for comparison against traditional malaria indices (parasite prevalence and entomological inoculation rate). Second, within individual post-ITN years, age-stratified seroprevalence data were analysed retrospectively for an abrupt drop in SCR by fitting alternative reversible catalytic conversion models that allowed for change in SCR. RESULTS: Generally, point measurements of seroprevalence, antibody titres and SCR produced consistent patterns indicating that a gradual but substantial drop in malaria transmission (46-70%) occurred from 1994 to 2007, followed by a marginal increase beginning in 2008 or 2009. In particular, proportionate changes in seroprevalence and SCR point estimates (relative to 1994 baseline values) for AMA-1 and CSP, but not MSP-119, correlated closely with trends in parasite prevalence throughout the entire 15-year study period. However, retrospective analyses using datasets from 2007, 2008 and 2009 failed to detect any abrupt drop in transmission coinciding with the timing of the 1997-1999 ITN trial. CONCLUSIONS: In this highly endemic area, serological markers were useful for generating accurate point estimates of malaria transmission intensity, but not for retrospective analysis of historical changes. Further investigation, including exploration of different malaria antigens and/or alternative models of population seroconversion, may yield serological tools that are more informative in high transmission settings.

Adverse drug events resulting from use of drugs with sulphonamide-containing anti-malarials and artemisinin-based ingredients: findings on incidence and household costs from three districts with routine demographic surveillance systems in rural Tanzania.

BACKGROUND: Anti-malarial regimens containing sulphonamide or artemisinin ingredients are widely used in malaria-endemic countries. However, evidence of the incidence of adverse drug reactions (ADR) to these drugs is limited, especially in Africa, and there is a complete absence of information on the economic burden such ADR place on patients. This study aimed to document ADR incidence and associated household costs in three high malaria transmission districts in rural Tanzania covered by demographic surveillance systems. METHODS: Active and passive surveillance methods were used to identify ADR from sulphadoxine-pyrimethamine (SP) and artemisinin (AS) use. ADR were identified by trained clinicians at health facilities (passive surveillance) and through cross-sectional household surveys (active surveillance). Potential cases were followed up at home, where a complete history and physical examination was undertaken, and household cost data collected. Patients were classified as having 'possible' or 'probable' ADR by a physician. RESULTS: A total of 95 suspected ADR were identified during a two-year period, of which 79 were traced, and 67 reported use of SP and/or AS prior to ADR onset. Thirty-four cases were classified as 'probable' and 33 as 'possible' ADRs. Most (53) cases were associated with SP monotherapy, 13 with the AS/SP combination (available in one of the two areas only), and one with AS monotherapy. Annual ADR incidence per 100,000 exposures was estimated based on 'probable' ADR only at 5.6 for AS/SP in combination, and 25.0 and 11.6 for SP monotherapy. Median ADR treatment costs per episode ranged from US$2.23 for those making a single provider visit to US$146.93 for patients with four visits. Seventy-three per cent of patients used out-of-pocket funds or sold part of their farm harvests to pay for treatment, and 19% borrowed money. CONCLUSION: Both passive and active surveillance methods proved feasible methods for anti-malarial ADR surveillance, with active surveillance being an important complement to facility-based surveillance, given the widespread practice of self-medication. Household costs associated with ADR treatment were high and potentially catastrophic. Efforts should be made to both improve pharmacovigilance across Africa and to identify strategies to reduce the economic burden endured by households suffering from ADR.

Routine delivery of artemisinin-based combination treatment at fixed health facilities reduces malaria prevalence in Tanzania: an observational study.

BACKGROUND: Artemisinin-based combination therapy (ACT) has been promoted as a means to reduce malaria transmission due to their ability to kill both asexual blood stages of malaria parasites, which sustain infections over long periods and the immature derived sexual stages responsible for infecting mosquitoes and onward transmission. Early studies reported a temporal association between ACT introduction and reduced malaria transmission in a number of ecological settings. However, these reports have come from areas with low to moderate malaria transmission, been confounded by the presence of other interventions or environmental changes that may have reduced malaria transmission, and have not included a comparison group without ACT. This report presents results from the first large-scale observational study to assess the impact of case management with ACT on population-level measures of malaria endemicity in an area with intense transmission where the benefits of effective infection clearance might be compromised by frequent and repeated re-infection. METHODS: A pre-post observational study with a non-randomized comparison group was conducted at two sites in Tanzania. Both sites used sulphadoxine-pyrimethamine (SP) monotherapy as a first-line anti-malarial from mid-2001 through 2002. In 2003, the ACT, artesunate (AS) co-administered with SP (AS + SP), was introduced in all fixed health facilities in the intervention site, including both public and registered non-governmental facilities. Population-level prevalence of Plasmodium falciparum asexual parasitaemia and gametocytaemia were assessed using light microscopy from samples collected during representative household surveys in 2001, 2002, 2004, 2005 and 2006. FINDINGS: Among 37,309 observations included in the analysis, annual asexual parasitaemia prevalence in persons of all ages ranged from 11% to 28% and gametocytaemia prevalence ranged from <1% to 2% between the two sites and across the five survey years. A multivariable logistic regression model was fitted to adjust for age, socioeconomic status, bed net use and rainfall. In the presence of consistently high coverage and efficacy of SP monotherapy and AS + SP in the comparison and intervention areas, the introduction of ACT in the intervention site was associated with a modest reduction in the adjusted asexual parasitaemia prevalence of 5 percentage-points or 23% (p < 0.0001) relative to the comparison site. Gametocytaemia prevalence did not differ significantly (p = 0.30). INTERPRETATION: The introduction of ACT at fixed health facilities only modestly reduced asexual parasitaemia prevalence. ACT is effective for treatment of uncomplicated malaria and should have substantial public health impact on morbidity and mortality, but is unlikely to reduce malaria transmission substantially in much of sub-Saharan Africa where individuals are rapidly re-infected.

dhfr and dhps genotype and sulfadoxine-pyrimethamine treatment failure in children with falciparum malaria in the Democratic Republic of Congo.

OBJECTIVE: To determine the relationship between mutations in dhfr and dhps and SP treatment failure in Plasmodium falciparum malaria in the Democratic Republic of the Congo (DRC). METHODS: Therapeutic efficacy trial was conducted in Rutshuru, Eastern DRC, between June and September 2002, comparing sulfadoxine-pyrimethamine (SP), SP plus amodiaquine (AQSP) and artesunate plus SP (ASSP) regimens for treating malaria in children under 5 years old. We genotyped 212 samples for mutations associated with SP resistance and investigated their association with treatment failure. RESULTS: In the SP arm, 61% of the subjects experienced treatment failure after 14 days. The failure rate was lower in the combination arms (AQSP: 32%, ASSP: 21%). The dhfr-108 and dhfr-51 mutations were nearly universal while 89% of the samples had at least one additional mutation at dhfr-59, dhps-437 or dhps-540. Dhps mutations had a bigger impact on treatment failure in children with high parasite density: for children with a parasite density <45 000 parasites/microl, the risk of treatment failure was 37% for mutations at dhps-437 and dhps-540 mutation and 21% for neither mutation [risk difference (RD) = 17%, 95% CI: -3%, 36%]. In children with a parasite density >45 000 parasites/microl, the treatment failure risk was 58% and 8% for children with both mutations or neither mutation, respectively (RD = 51%, 95% CI: 34%, 67%). CONCLUSIONS: Dhps-437 and dhps-540 are strongly associated with SP treatment failure and should be evaluated further as a method for surveillance of SP-based therapy in DRC.

Dispensary level pilot implementation of rapid diagnostic tests: an evaluation of RDT acceptance and usage by providers and patients--Tanzania, 2005.

BACKGROUND: Malaria rapid diagnostic tests (RDTs) may assist in diagnosis, improve prescribing practices and reduce potential drug resistance development. Without understanding operational issues or acceptance and usage by providers and patients, the costs of these tests may not be justified. OBJECTIVES: To evaluate the impact of RDTs on prescribing behaviours, assess prescribers' and patients' perceptions, and identify operational issues during implementation. METHODS: Baseline data were collected at six Tanzanian public dispensaries. RDTs were implemented for eight weeks and data collected on frequency of RDT use, results, malaria diagnoses and the prescription of antimalarials. Patients referred for RDTs completed a standardised exit interview. Qualitative methods assessed attitudes toward and satisfaction with RDTs, perceptions about the test and operational issues related to implementation. RESULTS: Of 595 patients at baseline, 200 (33%) were diagnosed clinically with malaria but had a negative RDT. Among the 2519 RDTs performed during implementation, 289 (11.5%) had a negative result and antimalarials prescribed. The proportion of "over-prescriptions" at baseline was 54.8% (198/365). At weeks four and eight this decreased to 16.1% (27/168) and 16.4% (42/256) respectively.A total of 355 patient or parent/caregiver and 21 prescriber individual interviews and 12 focus group discussions (FGDs) were conducted. Patients, caregivers and providers trusted RDT results, agreed that use of RDTs was feasible at dispensary level, and perceived that RDTs improved clinical diagnosis. Negative concerns included community suspicion and fear that RDTs were HIV tests, the need for additional supervision in interpreting the results, and increased work loads without added compensation. CONCLUSION: Overprescriptions decreased over the study period. There was a high degree of patient/caregiver and provider acceptance of and satisfaction with RDTs. Implementation should include community education, sufficient levels of training and supervision and consideration of the need for additional staff.

Malaria in pregnant women in an area with sustained high coverage of insecticide-treated bed nets.

BACKGROUND: Since 2000, the World Health Organization has recommended a package of interventions to prevent malaria during pregnancy and its sequelae that includes the promotion of insecticide-treated bed nets (ITNs), intermittent preventive treatment in pregnancy (IPTp), and effective case management of malarial illness. It is recommended that pregnant women in malaria-endemic areas receive at least two doses of sulphadoxine-pyrimethamine in the second and third trimesters of pregnancy. This study assessed the prevalence of placental malaria at delivery in women during 1st or 2nd pregnancy, who did not receive intermittent preventive treatment for malaria (IPTp) in a malaria-endemic area with high bed net coverage. METHODS: A hospital-based cross-sectional study was done in Ifakara, Tanzania, where bed net coverage is high. Primi- and secundigravid women, who presented to the labour ward and who reported not using IPTp were included in the study. Self-report data were collected by questionnaire; whereas neonatal birth weight and placenta parasitaemia were measured directly at the time of delivery. RESULTS: Overall, 413 pregnant women were enrolled of which 91% reported to have slept under a bed net at home the previous night, 43% reported history of fever and 62% were primigravid. Malaria parasites were detected in 8% of the placenta samples; the geometric mean (95%CI) placental parasite density was 3,457 (1,060-11,271) parasites/mul in primigravid women and 2,178 (881-5,383) parasites/mul in secundigravid women. Fifteen percent of newborns weighed <2,500 g at delivery. Self-reported bed net use was statistically associated with lower risk for low birth weight [OR 0.34 (95% CI: 0.16-0.74) and OR 0.22 (95% CI: 0.08-0.59) for untreated and treated bed nets, respectively], but was not associated with placental parasitaemia [OR 0.74 (0.21-2.68) and OR 1.64 (0.44-6.19) for untreated and treated bed nets, respectively]. CONCLUSION: The observed incidence of LBW and prevalence of placental parasitaemia at delivery suggests that malaria remains a problem in pregnancy in this area with high bed net coverage when eligible women do not receive IPTp. Delivery of IPTp should be emphasized at all levels of implementation to achieve maximum community coverage.

The anatomy of a malaria disaster: drug policy choice and mortality in African children.

Drug-resistant malaria is a substantial problem throughout Africa and most countries must regularly adapt their antimalarial drug policies to ensure a continued coverage of effective antimalarial treatment. The timing of drug policy change can be guided by several sources of data: molecular markers of resistance, in-vitro parasite sensitivity, parasitological and clinical failure rates, and community morbidity and mortality rates. Through mathematical simulations of the spread of parasite mutations through a population exposed to high-endemic malaria, we explore the causal and chronological relations between these indicators and show which of them are obscured or confounded by other factors. Taking into account the logistical and practical advantages and disadvantages of each type of data collection, we critically appraise the value of each indicator. A major problem is shown to be that drug efficacy as perceived by people at risk will remain high even after drugs have become almost completely ineffective, resulting in a lack of community pressure for drug policy change. We show that parasitological failure is the most sensitive and timely indicator, which allows around 2-3 years for drug policy change to be implemented, so as to prevent the most rapid rise in malaria-related mortality.

Epidemiologic study and containment of a nosocomial outbreak of severe acute respiratory syndrome in a medical center in Kaohsiung, Taiwan.

OBJECTIVE: We conducted an epidemiologic investigation at the beginning of a nosocomial outbreak of severe acute respiratory syndrome (SARS) to clarify the dynamics of SARS transmission, the magnitude of the SARS outbreak, and the impact of the outbreak on the community. METHODS: We identified all potential cases of nosocomially acquired SARS, linked them to the most likely infection source, and described the hospital containment measures. SETTING: A 2,300-bed medical center in Kaohsiung, Taiwan. RESULTS: A total of 55 cases of SARS were identified, and 227 hospital workers were quarantined. The index patient and neighboring patients were isolated. A chest physician team reviewed medical charts and chest radiographs and monitored the development of SARS in patients staying in the ward. The presence of underlying lung disease and immunocompromise in some patients made the diagnosis of SARS difficult. Some cases of SARS were diagnosed after the patients had died. Medical personnel were infected only if they cared for patients with unrecognized SARS, and caretakers played important roles in transmission of SARS to family members. As the number of cases of nosocomial SARS increased, the hospital closed the affected ward and expedited construction of negative-pressure rooms on other vacated floors for patient cohorting, and the last case in the hospital was identified 1 week later. CONCLUSIONS: Timely recognition of SARS is extremely important. However, given the limitations of SARS testing, possible loss of epidemic links, and the nonspecific clinical presentations in hospitalized patients, it is very important to establish cohorts of persons with low, medium, and high likelihoods of SARS acquisition. Rapid closure of affected wards may minimize the impact on hospital operations. Establishment of hospitals dedicated to appropriate treatment of patients with SARS might minimize the impact of the disease in future epidemics.

Rapid malaria screening and targeted treatment of United States-bound Montagnard refugees from Cambodia in 2002.

In 2002, a group of Montagnard refugees living in Cambodia was accepted for resettlement in the United States. Pre-departure malaria screening and targeted treatment was conducted to prevent morbidity, and minimize the potential for local malaria transmission post-arrival. We screened 902 of 906 refugees using rapid diagnostic tests (RDTs), microscopy, and polymerase chain reaction (PCR) analysis. Twelve (1.3%) RDT results were positive and 28 (3.1%) were indeterminate. Microscopy confirmed Plasmodium species in two of the positive RDT and one of the indeterminate results. Among a random 10% sample of negative RDT results (n = 86), none were positive by microscopy. The PCR confirmed the two microscopically (and RDT) positive specimens. The PCR result was negative for all other specimens tested. Eighteen (2.0%) refugees were treated with antimalarials. The RDTs were useful in this setting, facilitating timely, sensitive diagnosis and targeted treatment. Evaluations to determine the most appropriate interventions in other refugee settings should include cost-effectiveness analyses of alternative strategies.

Antibiotic resistance and serotype distribution of Streptococcus pneumoniae colonizing rural Malawian children.

Nasopharyngeal swabs were taken from 906 Malawian children <5 years old visiting rural health clinics. Pneumococcal colonization was high, 84% among all children, and occurred early, 65% of it in children <3 months old. Among pneumococcal isolates 46% were nonsusceptible to trimethoprim-sulfamethoxazole, and 21% were nonsusceptible to penicillin. Trimethoprim-sulfamethoxazole use in the previous month was a risk factor for trimethoprim-sulfamethoxazole and penicillin nonsusceptibility. Forty-three percent of isolates were serotypes included in the 7-valent pneumococcal conjugate vaccine, and 37% were vaccine-related serotypes, particularly 6A and 19A.

Adherence to antimalarial combination therapy with sulfadoxine-pyrimethamine and artesunate in rural Tanzania.

Artemisinin-containing antimalarial combination therapies are recommended to confront drug-resistant Plasmodium falciparum malaria. Among the questions surrounding whether these complex multidose treatments will be practical is to what extent patients complete the recommended doses. Combination therapy through coadministration of sulfadoxine-pyrimethamine plus artesunate was introduced as a first-line treatment for uncomplicated malaria in one district in Tanzania. Interventions to optimize correct use were also implemented. We observed 453 patient encounters at one health facility and recorded key practices as health workers dispensed the combination. A total of 253 patients were followed-up at 24 or 48 hours. Complete adherence measured at 48 hours reached 75.0%, based on self-report and tablet counts. This is substantially better than reported elsewhere and compares favorably with intervention studies to optimize adherence to chloroquine. Counseling about what to do if a patient vomits appears to have been an independent risk factor for nonadherence.

HIV immunosuppression and antimalarial efficacy: sulfadoxine-pyrimethamine for the treatment of uncomplicated malaria in HIV-infected adults in Siaya, Kenya.

BACKGROUND: The altered immune response of persons with human immunodeficiency virus (HIV) infection could result in increased rates of antimalarial treatment failure. We investigated the influence of HIV infection on the response to sulfadoxine-pyrimethamine treatment. METHODS: Febrile adults with Plasmodium falciparum parasitemia were treated with sulfadoxine-pyrimethamine and were monitored for 28 days. HIV status and CD4 cell count were determined at study enrollment. RESULTS: Of the adults enrolled in the study, 508 attended all follow-up visits, including 130 HIV-uninfected adults, 256 HIV-infected adults with a high CD4 cell count (> or =200 cells/ micro L), and 122 HIV-infected adults with a low CD4 cell count (<200 cells/ micro L). The hazard of treatment failure at day 28 of follow-up was significantly higher for HIV-infected adults with a low CD4 cell count (20.5%) than for HIV-uninfected adults (7.7%). Anemia (hemoglobin level, <110 g/L) modified the effect of HIV status on treatment failure. When we controlled for fever and parasite density, the hazard of treatment failure for HIV-infected adults with a low CD4 cell count and anemia was 3.4 times higher than that for HIV-uninfected adults (adjusted hazard ratio, 3.38; 95% confidence interval, 1.56-7.34). CONCLUSIONS: HIV-infected persons with a low CD4 cell count and anemia have an increased risk of antimalarial treatment failure. The response to malaria treatment in HIV-infected persons must be carefully monitored. Proven measures for the control and prevention of malaria must be incorporated into the basic package of services provided by HIV/acquired immunodeficiency syndrome care and treatment programs in malarious areas.

Prevalence of malaria parasitemia among clients seeking treatment for fever or malaria at drug stores in rural Tanzania 2004.

OBJECTIVE: To determine the prevalence of malaria parasitemia and other common illnesses among drug store clients in one rural community, with a view to the potential role of specialist drug stores in expanding coverage of effective malaria treatment to households in highly endemic areas. METHOD: Follow-back study of 2466 client visits selected from all 10 drug stores operating in the town of Ikwiriri between May 30 and August 31 2004. Of these, 521 (21.2%) were made by or on behalf of persons ill with fever or malaria. Two hundred and ninety three were eligible as residents of the surrounding nine villages and all agreed to participate in the study. Each patient was evaluated by a clinical officer and provided a blood sample for malaria on the day of the shop visit, either at the shop or at home. RESULTS: Only 50 (17.1%) visits by or on behalf of febrile patients resulted in the purchase of an antimalarial drug, while an antipyretic medication was obtained at 226 visits (77.1%). Clinicians diagnosed malaria in 63.8% of patients. Malaria parasites were identified in blood film samples from 24.2% (95% CI: 19.6, 29.5). This is double the parasite prevalence rate of 10.7% (95% CI: 8.6, 13.1) obtained from a household survey of 1004 healthy individuals selected from these villages at the same time. It is not significantly lower than the prevalence observed among 880 clients presenting with fever at health facilities in the district: 29.7% (95% CI: 23.0, 37.3). The prevalence of malaria parasitemia among children younger than 5 years whose families sought fever treatment from drug stores (42.1%; 95% CI: 31.4, 53.5) was equal to that of children presenting with fever at health facilities (42.5%; 95% CI: 25.0, 62.2). CONCLUSIONS: Currently, drug store clients do not obtain malaria-specific treatment in the majority of cases where it might be warranted. Parasitological findings indicate that drug store clients, especially children, are as likely to be infected with malaria as patients seeking care for similar illnesses at health facilities. Drug stores may be attractive partners for policy makers eager to engage the private retail sector in expanding coverage of malaria treatment.

Malaria surveillance--United States, 2002.

PROBLEM/CONDITION: Malaria is caused by any of four species of intraerythrocytic protozoa of the genus Plasmodium (i.e., P. falciparum, P. vivax, P. ovale, or 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 transmission. In the United States, cases can occur through exposure to infected blood products, by congenital transmission, or by local mosquitoborne transmission. Malaria surveillance is conducted to identify episodes of local transmission and to guide prevention recommendations for travelers. PERIOD COVERED: This report covers cases with onset of illness in 2002. DESCRIPTION OF SYSTEM: Malaria cases confirmed by blood film are reported to local and state health departments by health-care providers or laboratory staff. Case investigations are conducted by local and state health departments, and reports are transmitted to CDC through the National Malaria Surveillance System (NMSS). Data from NMSS serve as the basis for this report. RESULTS: CDC received reports of 1,337 cases of malaria with an onset of symptoms in 2002 among persons in the United States or one of its territories. This number represents a decrease of 3.3% from the 1,383 cases reported for 2001. P. falciparum, P. vivax, P. malariae, and P. ovale were identified in 52.3%, 25.4%, 2.8%, and 2.8% of cases, respectively. Eleven patients (0.8% of total) were infected by > or =2 species. The infecting species was unreported or undetermined in 213 (15.9%) cases. Compared with 2001, the number of reported malaria cases acquired in Asia (n = 171) and Africa (n = 903) increased by 4.3% and 1.9%, respectively, whereas the number of cases acquired in the Americas (n = 141) decreased by 41.2%. Of 849 U.S. civilians who acquired malaria abroad, 317 (37.3%) reported that they had followed a chemoprophylactic drug regimen recommended by CDC for the area to which they had traveled. Five patients became infected in the United States, one through congenital transmission, one probable transfusion-related, and three whose infection cannot be linked epidemiologically to secondary cases. Eight deaths were attributed to malaria. All deaths were caused by P. falciparum. INTERPRETATION: The 3.3% decrease in malaria cases in 2002, compared with 2001, resulted primarily from a marked decrease in cases acquired in the Americas, but this decrease was offset somewhat by an increase in the number of cases acquired in Africa and Asia. This limited decrease probably represents year-to-year variation in malaria cases, but also could have resulted from local changes in disease transmission, decreased travel to malaria-endemic regions, fluctuation in reporting to state and local health departments, or an increased use of effective antimalarial chemoprophylaxis. In the majority of reported cases, U.S. civilians who acquired infection abroad were not on an appropriate chemoprophylaxis regimen for the country in which they acquired malaria. PUBLIC HEALTH ACTION: Additional information was obtained concerning the eight fatal cases and the five infections acquired 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 travelers should use personal protection measures to prevent mosquito bites. Any person who has been to a malarious area and who subsequently experiences a fever or influenza-like symptoms should seek medical care immediately and report their travel history to the clinician; investigation should include a blood-film test for malaria. Malaria infections can be fatal if not diagnosed and treated promptly. Recommendations concerning malaria prevention can be obtained from CDC by calling the Malaria Hotline at 770-488-7788 or by accessing CDC's Internet site at http://www.cdc.gov/travel.

Prevalence of malaria parasitemia and accuracy of microscopic diagnosis in Haiti, October 1995 / Prevalencia de parasitemia por malaria y precisión del diagnóstico microscópico en Haití, octubre de 1995

In October 1995 the Ministry of Public Health and Population in Haiti surveyed 42 health facilities for the prevalence and distribution of malaria infection. They examined 1.083 peripheral blood smears from patients with suspected malaria; the overall slide positivity rate was 4.0 por cent (range, 0.0 por cent to 14.3 por cent). The rate was lowest among 1-to 4-year-old children (1.6 por cent) and highest among persons aged 15 and older (5.5 por cent). Clinical and microscopic diagnoses of malaria were unreliable; the overall sensitivity of microscopic diagnosis was 83.6 por cent, specificity was 88.6 por cent, and the predictive value of a positive slide was 22.2 por cent. Microscopic diagnoses need to be improved, and adequate surveillance must be reestablished to identify areas where transmission is most intense. The generally low level of malaria is encouraging and suggests that intensified control efforts targeted to the areas of highest prevalence could furhter diminish the effect of malaria in Haiti

En octubre de 1995 el Ministerio de Salud Pública y Población de Haití inspeccionó 42 establecimientos de salud para determinar la prevalencia y distribución de la infección por malaria. Se examinaron 1 803 frotis de sangre periférica obtenidos de pacientes con sospecha de tener esa enfermedad; la tasa general de positividad de los frotis fue de 4,0% (con un recorrido de 0,0 a 14,3%). La tasa más baja (1,6%) se observó en el grupo de niños de 1 a 4 años y la más alta en personas de 15 años de edad o mayores (5,5%). Los diagnósticos clínico y microscópico de la malaria fueron poco confiables; la sensibilidad general del diagnóstico microscópico fue de 83,6% y su especificidad de 88,6%, y el valor predictivo de un frotis positivo fue de 22,2%. Es preciso mejorar los diagnósticos microscópicos y reestablecer una vigilancia adecuada a fin de identificar las zonas donde la transmisión es más intensa. La frecuencia relativamente baja de la malaria es un dato alentador y sugiere que el refuerzo de las iniciativas de control dirigidas a las zonas de mayor prevalencia podría mitigar aun más el efecto de la malaria en Haití

Prevalence of malaria parasitemia and accuracy of microscopic diagnosis in Haiti, October 1995

In October 1995 the Ministry of Public Health and Population in Haiti surveyed 42 health facilities for the prevalence and distribution of malaria infection. They examined 1.083 peripheral blood smears from patients with suspected malaria; the overall slide positivity rate was 4.0 por cent (range, 0.0 por cent to 14.3 por cent). The rate was lowest among 1-to 4-year-old children (1.6 por cent) and highest among persons aged 15 and older (5.5 por cent). Clinical and microscopic diagnoses of malaria were unreliable; the overall sensitivity of microscopic diagnosis was 83.6 por cent, specificity was 88.6 por cent, and the predictive value of a positive slide was 22.2 por cent. Microscopic diagnoses need to be improved, and adequate surveillance must be reestablished to identify areas where transmission is most intense. The generally low level of malaria is encouraging and suggests that intensified control efforts targeted to the areas of highest prevalence could furhter diminish the effect of malaria in Haiti