Age-specific malaria seroprevalence rates: a cross-sectional analysis of malaria transmission in the Ouest and Sud-Est departments of Haiti.

BACKGROUND: Malaria transmission continues to occur in Haiti, with 25,423 confirmed cases of Plasmodium falciparum and 161,236 suspected infections reported in 2012. At low prevalence levels, passive surveillance measures, which rely primarily on reports from health systems, becomes less appropriate for capturing annual malaria incidence. To improve understanding of malaria transmission in Haiti, participants from the Ouest and Sud-Est departments were screened using a highly sensitive enzyme-linked immunosorbent assay (ELISA). METHODS: Between February and May 2013, samples were collected from four different sites including a rural community, two schools, and a clinic located in the Ouest and Sud-Est departments of Haiti. A total of 815 serum samples were screened for malaria antibodies using an indirect ELISA coated with vaccine candidates apical membrane antigen (AMA-1) and merozoite surface protein-1 (MSP-119). The classification of previous exposure was established by using a threshold value that fell three standard deviations above the mean absorbance for suspected seronegative population members (OD of 0.32 and 0.26 for AMA-1 and MSP-1, respectively). The observed seroprevalence values were used to fit a modified reverse catalytic model to yield estimates of seroconversion rates. RESULTS: Of the samples screened, 172 of 815 (21.1%) were AMA-1 positive, 179 of 759 (23.6%) were MSP-119 positive, and 247 of 815 (30.3%) were positive for either AMA-1 or MSP-1; indicating rates of previous infections between 21.1% and 30.3%. Not surprisingly, age was highly associated with the likelihood of previous infection (p-value <0.001). After stratification by age, the estimated seroconversion rate indicated that the annual malaria transmission in the Ouest and Sud-Est department is approximately 2.5% (95% CI SCR: 2.2%, 2.8%). CONCLUSIONS: These findings suggest that despite the absence of sustained malaria control efforts in Haiti, transmission has remained relatively low over multiple decades. Elimination in Haiti appears to be feasible; however, surveillance must continue to be strengthened in order to respond to areas with high transmission and measure the impact of future interventions.

Spectrum of outpatient illness in a school-based cohort in Haiti, with a focus on diarrheal pathogens.

Currently, there are only limited data available on rates of major diagnostic categories of illnesses among Haitian children. We have established a cohort of 1,245 students attending schools run by the Christianville Foundation in the Gressier/Leogane region of Haiti, for whom our group provides primary medical care. Among 1,357 clinic visits during the 2012-2013 academic year, the main disease categories (with rates per 1,000 child years of observation) included acute respiratory infection (ARI) (385.6 cases/1,000 child years of observation), gastrointestinal complaints (277.8 cases/1,000 child years), febrile illness (235.0 cases/1,000 child years), and skin infections (151.7 cases/1,000 child years). The most common diarrheal pathogen was enteroaggregative Escherichia coli (present in 17% of children with diarrhea); Vibrio cholerae O1 and norovirus were the next most common. Our data highlight the importance of better defining etiologies for ARI and febrile illnesses and continuing problems of diarrheal illness in this region, including mild cases of cholera, which would not have been diagnosed without laboratory screening.

Performance of the CareStart glucose-6-phosphate dehydrogenase (G6PD) rapid diagnostic test in Gressier, Haiti.

Administering primaquine (PQ) to treat malaria patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency can pose a serious risk of drug-induced hemolysis (DIH). New easy to use point-of-care rapid diagnostic tests are being developed as an alternative to labor-intensive spectrophotometric methods, but they require field testing before they can be used at scale. This study screened 456 participants in Gressier, Haiti using the Access Bio CareStart qualitative G6PD rapid detection test compared with the laboratory-based Trinity Biotech quantitative spectrophotometric assay. Findings suggest that the CareStart test was 90% sensitive for detecting individuals with severe deficiency and 84.8% sensitive for detecting individuals with moderate and severe deficiency compared with the Trinity Biotech assay. A high negative predictive value of 98.2% indicates excellent performance in determining those patients able to take PQ safely. The CareStart G6PD test holds much value for screening malaria patients to determine eligibility for PQ therapy.

Prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency in the Ouest and Sud-Est departments of Haiti.

Malaria remains a significant public health issue in Haiti, with chloroquine (CQ) used almost exclusively for the treatment of uncomplicated infections. Recently, single dose primaquine (PQ) was added to the Haitian national malaria treatment policy, despite a lack of information on the prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency within the population. G6PD deficient individuals who take PQ are at risk of developing drug induced hemolysis (DIH). In this first study to examine G6PD deficiency rates in Haiti, 22.8% (range 14.9%-24.7%) of participants were found to be G6PD deficient (class I, II, or III) with 2.0% (16/800) of participants having severe deficiency (class I and II). Differences in deficiency were observed by gender, with males having a much higher prevalence of severe deficiency (4.3% vs. 0.4%) compared to females. Male participants were 1.6 times more likely to be classified as deficient and 10.6 times more likely to be classified as severely deficient compared to females, as expected. Finally, 10.6% (85/800) of the participants were considered to be at risk for DIH. Males also had much higher rates than females (19.3% vs. 4.6%) with 4.9 times greater likelihood (p value 0.000) of having an activity level that could lead to DIH. These findings provide useful information to policymakers and clinicians who are responsible for the implementation of PQ to control and manage malaria in Haiti.