Prevalence of malaria and lymphatic filariasis in bateyes of the Dominican Republic

Results of Integrated Transmission Assessment Surveys for Lymphatic Filariasis and Malaria in Haiti, 2017-2022

Haiti is endemic for lymphatic filariasis (LF) and malaria, two mosquito-transmitted parasitic diseases targeted for elimination. The World Health Organization recommends a transmission assessment survey (TAS-1) to determine if LF prevalence is significantly beneath putative transmission thresholds (<2% antigen prevalence in Haiti, where Culex is the primary vector for Wuchereria bancrofti) to stop mass drug administration (MDA). Repeated TASs (TAS-2 and TAS-3) are recommended at 2-3-year intervals during post-treatment surveillance. From 2017 to 2022, The Carter Center assisted the Haitian Ministry of Public Health and Population in conducting 15 TASs in 11 evaluation units (EUs) encompassing 54 of the country's 146 districts. Children 6-7 years old were assessed for circulating filarial antigen (CFA) by Filariasis Test Strip: n = 5,239 in TAS-1; n = 11,866 in TAS-2; and n = 1,842 in TAS-3, of whom eight (0.15%), 20 (0.17%), and eight (0.43%) tested positive, respectively. The number of positive results in children was less than the threshold in each EU. When available, participants (n = 16,663) were also tested for malaria by rapid diagnostic test, with 31 (0.19%) children testing positive for Plasmodium falciparum. Integrated TASs provided an efficient means to collect epidemiological data for LF and malaria in Haiti. Results indicated thresholds for stopping and maintaining the halt of MDA for LF have been achieved in all EUs, with the halt of MDA for 571,358 people in four districts and the first TAS-3 surveys conducted in Haiti. Investigations are needed to assess the potential of ongoing LF transmission, especially in areas where CFA-positive samples were detected in TAS-3.

Delayed care-seeking in international migrant workers with imported malaria in China

BACKGROUND

Imported malaria cases continue to pose major challenges in China as well as in other countries that have achieved elimination. Early diagnosis and treatment of each imported malaria case is the key to successfully maintaining malaria elimination success. This study aimed to build an easy-to-use predictive nomogram to predict and intervene against delayed care-seeking among international migrant workers with imported malaria.

METHODS

A prediction model was built based on cases with imported malaria from 2012 to 2019, in Jiangsu Province, China. Routine surveillance information (e.g. sex, age, symptoms, origin country and length of stay abroad), data on the place of initial care-seeking and the gross domestic product (GDP) of the destination city were extracted. Multivariate logistic regression was performed to identify independent predictors and a nomogram was established to predict the risk of delayed care-seeking. The discrimination and calibration of the nomogram was performed using area under the curve and calibration plots. In addition, four machine learning models were used to make a comparison.

RESULTS

Of 2255 patients with imported malaria, 636 (28.2%) sought care within 24 h after symptom onset, and 577 (25.6%) sought care 3 days after symptom onset. Development of symptoms before entry into China, initial care-seeking from superior healthcare facilities and a higher GDP level of the destination city were significantly associated with delayed care-seeking among migrant workers with imported malaria. Based on these independent risk factors, an easy-to-use and intuitive nomogram was established. The calibration curves of the nomogram showed good consistency.

CONCLUSIONS

The tool provides public health practitioners with a method for the early detection of delayed care-seeking risk among international migrant workers with imported malaria, which may be of significance in improving post-travel healthcare for labour migrants, reducing the risk of severe malaria, preventing malaria reintroduction and sustaining achievements in malaria elimination.

Barriers to seeking health care among returning travellers with malaria: A systematic review

OBJECTIVE

To identify barriers to seeking health care among returning travellers with malaria with the aim of developing targeted interventions that improve early health care-seeking behaviour, diagnosis and treatment.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a systematic review of published medical literature, selecting studies that investigated and reported barriers to seeking health care among returning travellers and migrants with malaria. In total, 633 articles were screened, of which four studies met the inclusion criteria after a full-text review.

RESULTS

The four studies reported barriers to seeking healthcare among returning travellers in China, the United States, Thailand and the Dominican Republic. Three studies had an observational design. The identified barriers were summarised based on the appraisal delay, illness delay and utilisation delay stages. During appraisal delays, low awareness of malaria was the most significant factor. Once the patient assessed that he or she was ill, belonging to a specific minority ethnicity, being infected with P. vivax and receiving a low level of social support were predictors of delayed health care-seeking. Finally, the most significant factor associated with utilisation delays was the monetary cost.

CONCLUSION

The health care-seeking behaviour of returning travellers with malaria should be further investigated and improved. Addressing the identified barriers and gaps in health care-seeking behaviour among returning travellers with malaria, particularly among groups at high risk of travel-associated infections, is important to prevent severe disease and deaths as well as secondary transmission and epidemics.

Lymphatic filariasis elimination in the Dominican Republic: History, progress, and remaining steps

Lymphatic filariasis (LF) is a mosquito-transmitted parasitic disease that is a leading cause of disability globally. The island of Hispaniola, which the Dominican Republic shares with Haiti, accounts for approximately 90% of LF cases in the Americas region. In 1998, the Dominican Ministry of Public Health created the Program to Eliminate Lymphatic Filariasis (PELF) with the goal of eliminating LF transmission by 2020. Baseline mapping revealed 19 (12% of total) endemic municipalities clustered into three geographic foci (Southwest, La Ciénaga and East), with a total at-risk population of 262,395 people. Beginning in 2002, PELF sequentially implemented mass drug administration (MDA) in these foci using albendazole and diethylcarbamazine (DEC). In total, 1,174,050 treatments were given over three to five annual rounds of house-to-house MDA per focus with a median coverage of 81.7% (range 67.4%–92.2%). By 2018, LF antigen prevalence was less than 2% in all foci, thus meeting criteria to stop MDA and begin post-treatment surveillance (PTS). This success has been achieved against a shifting landscape of limited domestic funding, competing domestic public health priorities, and sporadic external donor support. Remaining steps include the need to scale-up morbidity management and disability prevention services for LF and to continue PTS until LF transmission is interrupted across Hispaniola.

Lymphatic filariasis (LF) is a neglected tropical disease caused by thin worms transmitted to humans by the bites of mosquitoes. LF is a leading cause of disability globally, resulting from the long-term physical (swelling of legs and genitals) and psycho-social impacts on affected individuals. The Dominican Republic is one of four LF-endemic countries in the Americas. This report describes the efforts to eliminate the disease in the country, including a review of disease mapping and implementation of mass drug administration (MDA)—the provision of safe and effective medicine to at-risk communities—to interrupt parasite transmission. Particular emphasis is given to program planning and community mobilization for MDA due to the divergent environments of endemic foci, which ranged from rural agricultural regions to densely populated urban neighborhoods. Impact evaluation data for each focus demonstrates interruption of LF transmission and that criteria to stop MDA have been met. Finally, plans for post-treatment surveillance and the scale-up of clinical care services for those who remain affected by chronic LF are presented—required elements for eliminating LF as a public health problem.

Prevalence of Diabetes, Prediabetes, and Associated Risk Factors Among Agricultural Village Residents in the Dominican Republic

This study examined the prevalence and risk factors of prediabetes and type 2 diabetes among residents of agricultural settlement villages (bateyes) in the Dominican Republic. From March to April 2016, a cross-sectional, multi-stage cluster survey was conducted across the country's three agricultural regions (southwest, east, and north). At selected households, an adult completed a questionnaire to assess demographics, diabetes knowledge, and care, and two household residents of any age provided finger-prick blood samples that were analyzed for hemoglobin A1c (HbA1c). HbA1c was categorized as normal (< 5.7%), prediabetic (5.7-6.4%), or diabetic (≥ 6.5%). The prevalence rates of diabetes and prediabetes were 8.6% (95% confidence interval [CI], 6.2-11.8%) and 20.4% (95% CI, 17.9-23.2%), respectively, among all participants (N = 1293; median age, 35 years; range, 2-96 years), and 10.0% (95% CI, 7.2-13.8%) and 20.0% (95% CI, 17.4-23.0%), respectively, among adults 18 years or older (N = 730). The average age of participants with diabetes was 47.2 years. The average age of participants with prediabetes was 40.7 years. Among adult questionnaire respondents, 64.8% of all participants and 39.4% of patients with diabetes had not been tested for diabetes previously. Among patients with diabetes, 28.4% were previously diagnosed; 1.2% of prediabetes patients were previously diagnosed. Half (50.7%) of the respondents had heard of diabetes. The majority (94.1%) of patients previously diagnosed with diabetes reported using diabetes medication. Among both undiagnosed and previously diagnosed patients with diabetes, diabetes knowledge, previous diabetes testing, and diabetes care-seeking were lowest among Haitian-born participants. A high burden of undiagnosed diabetes and deficiencies in diabetes knowledge, access to care, and diagnosis exist among all batey inhabitants, but most acutely among Haitians. Improvements will require a multi-sectoral approach.

Rapid ethnographic assessment for potential anti-malarial mass drug administration in an outbreak area of Santo Domingo, Dominican Republic

BACKGROUND

In the Dominican Republic, a recent outbreak of malaria in the capital, Santo Domingo, threatens efforts to eliminate the disease. Mass drug administration (MDA) has been proposed as one strategy to reduce transmission. The success of MDA is contingent upon high levels of acceptance among the target population. To inform the design of future MDA campaigns, this rapid ethnographic assessment examined malaria-related knowledge and attitudes toward malaria MDA among residents of a transmission focus in Santo Domingo.

METHODS

In October 2019, a rapid ethnographic assessment was conducted in the Los Tres Brazos transmission focus, which had not previously received MDA. National malaria programme staff conducted 61 structured interviews with key informants, recorded observations, and held 72 informal conversations. Using a grounded theory approach, data were analysed during three workshop sessions with research team members.

RESULTS

Among those who had heard of malaria in the structured interviews (n = 39/61; 64%), understanding of the disease was largely based on personal experience from past outbreaks or through word-of-mouth. Community health workers (promotores) were trusted for health information and malaria diagnosis more so than professional clinicians. No participant (0%) was familiar with malaria MDA. After learning about MDA, almost all study participants (92%) said that they would participate, seeing it as a way to care for their community. Reasons for not participating in future MDA included not trusting drug administrators, feeling reluctant to take unprescribed medicine, and fear of missing work. Additional identified challenges to MDA included reaching specific demographic groups, disseminating effective MDA campaign messages, and managing misinformation and political influence.

CONCLUSION

Residents appear accepting of MDA despite a lack of prior familiarity. Successful MDA will depend on several factors: fostering relationships among community-based health workers, clinicians, community leaders, and others; developing clear health messages that use local terms and spreading them through a variety of media and social networks; and contextualizing MDA as part of a broader effort to promote community health.

Progress towards elimination of lymphatic filariasis in the Americas region

In South and Central America, lymphatic filariasis (LF) is caused by Wuchereria bancrofti, which is transmitted by Culex quinquefasciatus, the only vector species in this region. Of the seven countries considered endemic for LF in the Americas in the last decade, Costa Rica, Suriname and Trinidad and Tobago were removed from the World Health Organization list in 2011. The remaining countries, Brazil, Dominican Republic, Guyana and Haiti, have achieved important progress in recent years. Brazil was the first country in the Americas to stop mass drug administration (MDA) and to establish post-MDA surveillance. Dominican Republic stopped MDA in all LF-endemic foci: La Ciénaga and Southwest passed the third Transmission Assessment Survey (TAS) and the Eastern focus passed TAS-1 in 2018. Haiti passed the TAS and interrupted transmission in >80% of endemic communes, achieving effective drug coverage. Guyana implemented effective coverage in MDAs in 2017 and 2018 and in 2019 scaled up the treatment for 100% of the geographical region, introducing ivermectin in the MDA in order to achieve LF elimination by the year 2026. The Americas region is on its way to eliminating LF transmission. However, efforts should be made to improve morbidity management to prevent disability of the already affected populations.

Perceived discrimination in bateyes of the Dominican Republic: results from the Everyday Discrimination Scale and implications for public health programs

BACKGROUND

Discrimination is a major driver of health disparities among minority groups and can impede the reach of public health programs. In the Dominican Republic, residents of bateyes, or agricultural 'company towns,' often face barriers to health care. This study examined the extent of perceived discrimination among batey populations and places the findings within the context of disease elimination efforts.

METHODS

In March-April 2016, a stratified, multi-stage cluster survey that included the 9-item Everyday Discrimination Scale (EDS) was conducted among residents (n = 768) of bateyes across the Dominican Republic. Exploratory factor analysis, differential item functioning, and linear and logistic regression were used to assess associations between EDS scores, ethnic group status, reasons for discrimination, and healthcare-seeking behavior.

RESULTS

Three ethnic groups were identified in the population: Haitian-born persons (42.5%), Dominican-born persons with Haitian descent (25.5%), and Dominican-born persons without Haitian descent (32.0%). Mean EDS scores (range 0-45) were highest among persons born in Haiti (18.2, 95% confidence interval [CI] = 16.4-20.1), followed by persons with Haitian descent (16.5, 95% CI = 14.9-18.0), and those without Haitian descent (13.3, 95% CI = 12.1-14.5). Higher EDS scores were significantly associated with Haitian birth (β = 6.8, 95% CI = 4.2-9.4; p < 0.001) and Haitian descent (β = 6.1, 95% CI = 3.2-9.0; p < 0.001). Most respondents (71.5%) had scores high enough to elicit reasons for their discrimination. Regardless of ethnic group, poverty was a common reason for discrimination, but Haitian-born and Haitian-descended people also attributed discrimination to their origin, documentation status, or skin color. EDS scores were not significantly associated with differences in reported care-seeking for recent fever (β = 1.7, 95% CI = - 1.4-4.9; p = 0.278).

CONCLUSION

Perceived discrimination is common among batey residents of all backgrounds but highest among Haitian-born people. Discrimination did not appear to be a primary barrier to care-seeking, suggesting other explanations for reduced care-seeking among Haitian populations. Public health community engagement strategies should avoid exacerbating stigma, build active participation in programs, and work towards community ownership of disease control and elimination goals.