Impact assessment of onchocerciasis through lymphatic filariasis transmission assessment surveys using Ov-16 rapid diagnostic tests in Sierra Leone

BACKGROUND

Onchocerciasis is endemic in 14 of Sierra Leone's 16 districts with high prevalence (47-88.5%) according to skin snips at baseline. After 11 rounds of mass treatment with ivermectin with good coverage, an impact assessment was conducted in 2017 to assess the progress towards eliminating onchocerciasis in the country.

METHODS

A cluster survey was conducted, either integrated with lymphatic filariasis (LF) transmission assessment survey (TAS) or standalone with the LF TAS sampling strategy in 12 (now 14) endemic districts. Finger prick blood samples of randomly selected children in Grades 1-4 were tested in the field using SD Bioline Onchocerciasis IgG4 rapid tests.

RESULTS

In total, 17,402 children aged 4-19 years in 177 schools were tested, and data from 17,364 children aged 4-14 years (14,230 children aged 5-9 years) were analyzed. Three hundred forty-six children were confirmed positive for Ov-16 IgG4 antibodies, a prevalence of 2.0% (95% CI 1.8-2.2%) in children aged 4-14 years with prevalence increasing with age. Prevalence in boys (2.4%; 95% CI 2.1-2.7%) was higher than in girls (1.6%; 95% CI 1.4-1.9%). There was a trend of continued reduction from baseline to 2010. Using data from children aged 5-9 years, overall prevalence was 1.7% (95% CI 1.5-1.9%). The site prevalence ranged from 0 to 33.3% (median prevalence = 0.0%): < 2% in 127 schools, 2 to < 5% in 34 schools and ≥ 5% in 16 schools. There was a significant difference in average prevalence between districts. Using spatial analysis, the Ov-16 IgG4 antibody prevalence was predicted to be < 2% in coastal areas and in large parts of Koinadugu, Bombali and Tonkolili Districts, while high prevalence (> 5%) was predicted in some focal areas, centered in Karene, Kailahun and Moyamba/Tonkolili.

CONCLUSIONS

Low Ov-16 IgG4 antibody prevalence was shown in most areas across Sierra Leone. In particular, low seroprevalence in children aged 5-9 years suggests that the infection was reduced to a low level after 11 rounds of treatment intervention. Sierra Leone has made major progress towards elimination of onchocerciasis. However, attention must be paid to those high prevalence focal areas.

The Threat of Vector-Borne Diseases in Sierra Leone

Sierra Leone is vulnerable to a wide range of vector-borne diseases transmitted by mosquitoes, tsetse flies, black flies, and other vectors. Malaria, lymphatic filariasis, and onchocerciasis have posed the greatest threat and have received the most attention in terms of vector control and capacity for diagnosis. However, malaria infection rates remain high, and there is evidence of circulation of other vector-borne diseases, such as chikungunya and dengue, which may go undiagnosed and unreported. The limited understanding of the prevalence and transmission of these diseases restricts the capacity for predicting outbreaks, and impedes the planning of appropriate responses. We review the available literature and gather expert opinions from those working in the country to report on the status of vector-borne disease transmission and control in Sierra Leone, and present an assessment of the threats of these diseases. Our discussions highlight an absence of entomological testing for disease agents and the need for more investment in surveillance and capacity strengthening.

Prevalence of malaria and helminth infections in rural communities in northern Sierra Leone, a baseline study to inform Ebola vaccine study protocols

Introduction

Recurrent parasitic infections may influence the immune response to vaccines. In the Partnership for Research on Ebola VACcinations extended follow-UP and clinical research capacity build-UP (PREVAC-UP) study being undertaken in Mambolo, northern Sierra Leone, participants are being followed up to assess the potential impact of exposure to malaria and/or helminth infections on long-term immune response to two Ebola vaccines. To support the development of the assays that will be used in this evaluation, a parasitological survey was conducted in Mambolo between November 2019 and February 2020.

Methods

Healthy individuals aged ≥1 year who were resident in Mambolo Chiefdom were selected using a stratified sampling approach and questionnaires were administered to explore their sociodemographic characteristics. Microscopy was used to detect malaria parasites, intestinal helminths and urinary schistosome infections. Rapid blood tests were used to detect infections with Onchocerca volvulus and Wuchereria bancrofti. We estimated the overall prevalence of these infections and used adjusted logistic regression models to explore risk factors for malaria and hookworm infection.

Results

Eight hundred and fifteen (815) residents, 50.9% of whom were female were surveyed. Overall, 309 (39.1%) of 791 persons tested for malaria had a positive blood slide; Plasmodium falciparum was the dominant species. Helminth infection was detected in 122 (15.0%) of 815 stool samples including three mixed infections. The helminth infections comprised 102 (12.5%) cases of hookworm, 11 (1.3%) cases of Trichuris trichiura, 10 (1.2%) cases of Schistosoma mansoni and two (0.2%) cases of Ascaris lumbricoides. Being male (OR = 2.01, 95% CI 1.15–3.50) and residing in a non-riverine community (OR = 4.02, 95%CI 2.32–6.98) were the factors associated with hookworm infection. Onchocerca volvulus and Wuchereria bancrofti infections were found in 3.3% and 0.4% of participants respectively.

Conclusion

Malaria and hookworm are the most prevalent parasite infections and those most likely to influence long-term immune response to Ebola vaccines among the trial participants.

Community-wide prevalence and intensity of soil-transmitted helminthiasis and Schistosoma mansoni in two districts of Sierra Leone

In Sierra Leone, nationally powered school-based surveys have documented significant progress in the control of soil-transmitted helminthiasis (STH) and schistosomiasis. In order to assess the district-level prevalence and intensity of infection among key at-risk groups outside of school age children (SAC), we conducted a multi-stage, cluster-sample household survey in Bo and Kenema districts in May 2018. From both districts, we examined 1,282 pre-school age children (PSAC), 730 school age children (SAC), and 517 adults over 14 years (including 387 women of reproductive age, or WRA) for STH and Schistosoma mansoni infection using Kato Katz technique. In Bo, STH prevalence was 8.0% (95% Upper Confidence Limit 10.2%) in PSAC, 6.4% (95% Upper Confidence Limit 9.0%) in SAC, 14.1% (95% Upper Confidence Limit 17.4%) in all adults and 11.9% (95% Upper Confidence Limit 17.4%) in WRA. In Kenema, STH prevalence was 18.1% (95% Upper Confidence Limit 20.5%) in PSAC, 17.3% (95% Upper Confidence Limit 20.7%) in SAC, and 16.9% (95% Upper Confidence Limit 20.5%) in all adults and 16.9% (95% Upper Confidence Limit 22.6%) in WRA. Hookworm species were the most prevalent of STH in both districts overall. The overall prevalence of S. mansoni was <10% in Bo and <20% in Kenema, and was similar across age groups. No moderate or heavy intensity STH infections or heavy intensity S. mansoni infections, as per World Health Organization (WHO) classification, were detected in either district. Sanitation variables, such as toilet access and quality, were independently associated with STH and S. mansoni infection. In Kenema, STH prevalence in SAC was within the WHO-defined range for annual treatment, whereas a previous nationally-powered survey estimated it to lie within the range of treatment once per two years. By utilizing community-based sampling, we were able to assess prevalence among WRA and make recommendations based on current guidance from WHO. To continue toward elimination of STH and S. mansoni as a public health problem, resources should be mobilized to increase access to and uptake of improved sanitation at community and household levels.

Gender intersections identified whilst transitioning mass vitamin A supplementation into an integrated reproductive and child health programme in Sierra Leone

Since 2006, Sierra Leone has achieved high rates of vitamin A supplementation (VAS) coverage (>88%) during mass campaigns. In 2017, campaigns started transitioning to routine VAS within a six-monthly contact point for integrated reproductive and child health (RCH) services. This contact point included improved counselling and provision of modern contraceptives; throughout this transition high VAS coverage (>85%) has been maintained. VAS programmes have traditionally operated on the assumption that they are gender-neutral, but recent research suggests these programmes should re-examine how they interact with gender. This qualitative study examined intersections between gender and Sierra Leone's integrated VAS programming by conducting 32 individual interviews with parents, district health management and national staff, and six focus group discussions with health workers and community health workers (CHWs) in three pilot program districts. The study found that most senior health positions are held by males, and the lower cadres of majority female health workers often felt unsupported/disrespected by their male superiors and male CHW supervisees, or that their years of experience were overlooked in favour of the academic qualifications of less experienced male colleagues. Gender was not included in program training, and most staff did not have a good understanding of gender intersections; however, health workers actively engaged in awareness raising with male stakeholders to increase male involvement in RCH. Routine delivery requires mothers to invest time and money to access health facilities, where most mothers felt that better qualified staff were able to offer better advice and more services. Health workers felt that outreach services utilizing CHWs could decrease this time/money burden; however, CHWs are unqualified to provide counselling and provision of modern contraception, and there are fewer female CHWs. Records kept in health facilities record VAS by sex, but monthly reports submitted to the district and onwards to the national Health Management Information System are not disaggregated by sex. Programme and policymakers should consider improving the representation by females in senior, decision-making positions, integrating gender information into all trainings, supporting female health workers, training and recruiting more female CHWs, and reporting VAS coverage by sex.

Model-Based Geostatistical Methods Enable Efficient Design and Analysis of Prevalence Surveys for Soil-Transmitted Helminth Infection and Other Neglected Tropical Diseases

Maps of the geographical variation in prevalence play an important role in large-scale programs for the control of neglected tropical diseases. Precontrol mapping is needed to establish the appropriate control intervention in each area of the country in question. Mapping is also needed postintervention to measure the success of control efforts. In the absence of comprehensive disease registries, mapping efforts can be informed by 2 kinds of data: empirical estimates of local prevalence obtained by testing individuals from a sample of communities within the geographical region of interest, and digital images of environmental factors that are predictive of local prevalence. In this article, we focus on the design and analysis of impact surveys, that is, prevalence surveys that are conducted postintervention with the aim of informing decisions on what further intervention, if any, is needed to achieve elimination of the disease as a public health problem. We show that geospatial statistical methods enable prevalence surveys to be designed and analyzed as efficiently as possible so as to make best use of hard-won field data. We use 3 case studies based on data from soil-transmitted helminth impact surveys in Kenya, Sierra Leone, and Zimbabwe to compare the predictive performance of model-based geostatistics with methods described in current World Health Organization (WHO) guidelines. In all 3 cases, we find that model-based geostatistics substantially outperforms the current WHO guidelines, delivering improved precision for reduced field-sampling effort. We argue from experience that similar improvements will hold for prevalence mapping of other neglected tropical diseases.

The impact on key indicators of reproductive and child health after changes in program modalities in Sierra Leone, 2019

BACKGROUND AND AIMS

In 2018, the transition to routine vitamin A supplementation (VAS) was integrated with caregivers' preparation of nutritious complementary food from local produce and confidential counseling and provision of modern contraceptives. In 2019, funding for complementary food ceased and Community Health Workers (CHWs) were trained to track defaulters, while national efforts to improve Health Management Information Systems, supply chains and reduce teenage pregnancies were intensified. We report on key indicators after these changes and in comparison, to those previously published.

METHODS

The same Lot Quality Assurance Sampling methodology was used in both assessments: 19 villages were randomly selected in each of five lots in each of three districts then caregivers of children 6-59 months age randomly selected and interviewed.

RESULTS

Coverage of VAS, Albendazole, and Pentavalent 3 before and after these changes was over 80%, 75%, and 80% respectively, equitable by sex, age, caregiver's religion, and educational status. Comparison with 2018 found more lots failed to reach 80% VAS by verbal affirmation (10 vs 2), and coverage in one district (Bo) had dropped (77.5% vs 92.3%). Fewer caregivers were aware that VAS should be taken every 6 months (27% vs 50%), that complementary feeding should start at 6 months (63% vs 77%) or were providing minimal dietary diversity (27% vs 45%). There was an increase in caregivers using modern contraception (45% vs 35%), obtaining information about contraception from a friend (14% vs 9%), while fewer thought country rope/herbs (traditional contraceptives) were "effective" (11% vs 21%) and stockouts of contraceptives at health facilities had dropped (24% vs 55%). Stipends for CHWs cost approximately $750 K vs complementary food: $112 K.

CONCLUSION

Overall coverage for VAS, Albendazole, and Pentavalent remained effective but VAS had dropped significantly in one district. Complementary feeding practices had declined. Awareness, uptake, and contraceptives supply chains had improved.

Achievements and challenges of lymphatic filariasis elimination in Sierra Leone

Background

Lymphatic filariasis (LF) is targeted for elimination in Sierra Leone. Epidemiological coverage of mass drug administration (MDA) with ivermectin and albendazole had been reported >65% in all 12 districts annually. Eight districts qualified to implement transmission assessment survey (TAS) in 2013 but were deferred until 2017 due to the Ebola outbreak (2014–2016). In 2017, four districts qualified for conducting a repeat pre-TAS after completing three more rounds of MDA and the final two districts were also eligible to implement a pre-TAS.

Methodology/Principal findings

For TAS, eight districts were surveyed as four evaluation units (EU). A school-based survey was conducted in children aged 6–7 years from 30 clusters per EU. For pre-TAS, one sentinel and one spot check site per district (with 2 spot check sites in Bombali) were selected and 300–350 persons aged 5 years and above were selected. For both surveys, finger prick blood samples were tested using the Filariasis Test Strips (FTS).

For TAS, 7,143 children aged 6–7 years were surveyed across four EUs, and positives were found in three EUs, all below the critical cut-off value for each EU. For the repeat pre-TAS/pre-TAS, 3,994 persons over five years of age were surveyed. The Western Area Urban had FTS prevalence of 0.7% in two sites and qualified for TAS, while other five districts had sites with antigenemia prevalence >2%: 9.1–25.9% in Bombali, 7.5–19.4% in Koinadugu, 6.1–2.9% in Kailahun, 1.3–2.3% in Kenema and 1.7% - 3.7% in Western Area Rural.

Conclusions/Significance

Eight districts in Sierra Leone have successfully passed TAS1 and stopped MDA, with one more district qualified for conducting TAS1, a significant progress towards LF elimination. However, great challenges exist in eliminating LF from the whole country with repeated failure of pre-TAS in border districts. Effort needs to be intensified to achieve LF elimination.

Lymphatic filariasis or elephantiasis is targeted for elimination in Sierra Leone, with annual mass treatment with ivermectin and albendazole, and required coverage was achieved in all 12 districts annually. In 2017, transmission assessment survey (TAS) was conducted in eight districts to assess whether treatment can be stopped and pre-TAS was conducted in six other districts to assess whether TAS can be conducted. Eight TAS districts were surveyed as four evaluation units (EU), and a school-based survey was conducted in 1703–1926 children aged 6–7 years from 30 clusters per EU. Six pre-TAS districts were surveyed with one sentinel and one/two spot check sites per district and 300–350 persons aged ≥5 years were tested. All tests were using the Filariasis Test Strips with finger prick blood samples. There were 0–7 positive cases in each TAS EU respectively, all below the critical cut-off value, confirming that mass treatment was no longer needed in these eight districts, a significant progress towards LF elimination. One district had prevalence of <1% in two sites and qualified for TAS, while other five districts had sites with prevalence >2%, suggesting that mass treatment needs to continue. Repeated failure of pre-TAS poses great challenge to eliminate LF in Sierra Leone.YMB is the former NTDP manager and coordinated the MDAs with AC and MS. JBK designed and oversaw the early NTDP and baseline surveys. JP, MB designed and led the TAS, pre-TAS field work data collection. MB and VRS conducted the data analysis. VRS and MH reanalysed the coverage data. YZ produced the point prevalence map. MH drafted the manuscript. MH and YZ revised the manuscript. All authors reviewed and approved the final manuscript.

Routine vitamin A supplementation and other high impact interventions in Sierra Leone

In 2017, transition to routine vitamin A supplementation (VAS) commenced as an integrated reproductive and child health service including vaccinations, Albendazole for deworming, complementary feeding demonstrations, ‘quality’ family planning counselling and provision of modern contraceptives. After 10 months, a lot quality assurance sampling survey evaluated coverage of these interventions. Each of three districts was divided into five supervision areas (lots), and 19 villages were randomly selected in each lot proportional to population size. Households were randomly selected, and a questionnaire was administered to a caregiver of a child 6–11, 12–23 and 24–59 months in each village. Overall, caregivers of 855 children were interviewed, and 19 questionnaires were completed for each age group (6–11, 12–23 and 24–59 months) in each of the five lots in each district. All lots in one district passed the threshold of 80% for VAS and 75% coverage for Albendazole, and two lots failed for either VAS/Albendazole in the other two districts. Overall, weighted VAS coverage for children 6–59 months was 86.9%, and weighted Albendazole coverage for children 12–59 months was 80.9%. Most caregivers (77.2%) knew that complementary feeding should be introduced at 6 months, 44.9% were providing three or more (of six) food groups, 84.9% were aware of family planning and 37.5% were using a modern contraceptive. Integration of reproductive and child health services appears to be a suitable platform for routine VAS and Albendazole whilst improving complementary feeding practices and access to family planning.

Are census data accurate for estimating coverage of a lymphatic filariasis MDA campaign? Results of a survey in Sierra Leone

BACKGROUND

Preventive chemotherapy was administered to 3.2 million Sierra Leoneans in 13 health districts for lymphatic filariasis, onchocerciasis, and soil transmitted helminthes from October 2008 to February 2009. This paper aims to report the findings of a coverage survey conducted in 2009, compare the coverage survey findings with two reported rates for lymphatic filariasis coverage obtained using pre-mass drug administration (MDA) registration and national census projections, and use the comparison to understand the best source of population estimates in calculating coverage for NTD programming in Sierra Leone.

METHODOLOGY/PRINCIPAL FINDINGS

Community drug distributors (CDDs) conducted a pre- MDA registration of the population. Two coverage rates for MDA for lymphatic filariasis were subsequently calculated using the reported number treated divided by the total population from: 1) the pre-MDA register and 2) national census projections. A survey was conducted to validate reported coverage data. 11,602 persons participated (response rate of 76.8%). Overall, reported coverage data aggregated to the national level were not significantly different from surveyed coverage (z-test >0.05). However, estimates based on pre-MDA registration have higher agreement with surveyed coverage (mean Kendall's W = 0.68) than coverage calculated with census data (mean Kendall's = 0.59), especially in districts with known large-scale migration, except in a highly urban district where it was more challenging to conduct a pre-MDA registration appropriately. There was no significant difference between coverage among males versus females when the analyses were performed excluding those women who were pregnant at the time of MDA. The surveyed coverage estimate was near or below the minimum 65% epidemiological coverage target for lymphatic filariasis MDA in all districts.

CONCLUSION/SIGNIFICANCE

These results from Sierra Leone illustrate the importance of choosing the right denominator for calculating treatment coverage for NTD programs. While routinely reported coverage results using national census data are often good enough for programmatic decision making, census projections can quickly become outdated where there is substantial migration, e.g. due to the impact of civil war, with changing economic opportunities, in urban settings, and where there are large migratory populations. In districts where this is known to be the case, well implemented pre-MDA registration can provide better population estimates. Pre-MDA registration should, however, be implemented correctly to reduce the risk of missing pockets of the population, especially in urban settings.

Schistosomiasis in School Age Children in Sierra Leone After 6 Years of Mass Drug Administration With Praziquantel

Historic data and baseline surveys showed schistosomiasis as highly/moderately endemic in 7 of 14 districts in Sierra Leone, justifying annual/biennial mass drug administration (MDA) with praziquantel. MDA commenced in 2009 and reported treatment coverage had been above the World Health Organization recommended 75% of target population. Assessment in 2012 showed significant reduction in infection. In 2016, another national school-based survey was conducted to evaluate the progress. Two schools from each category (high, moderate or low) of endemic communities in each MDA district and five schools in non-MDA districts were selected. Fifty children (25 boys and 25 girls) aged 9-14 years were randomly selected per school. Parasitological examination of 1,980 stool and 1,382 urine samples were conducted. Overall Schistosoma mansoni prevalence in the seven MDA districts decreased to 20.4% (95% CI: 18.7-22.3%) in 2016 from 42.2% (95% CI: 39.8-44.5%) at baseline (p < 0.0001). Mean overall S. mansoni intensity of infection reduced to 52.8 epg (95% CI: 43.2-62.4 epg) in 2016 from 100.5 epg (95% CI: 88.7-112.3 epg) at baseline (p < 0.001). The prevalence of Schistosoma haematobium in the five MDA districts that had baseline prevalence data decreased to 2.2% (95% CI: 1.5-3.1%) in 2016 from 18.3% (95% CI: 16.3-20.5%) at baseline (p < 0.0001). Mean overall intensity of infection increased to 1.12 e/10 ml (95% CI: 0.55-0.1.70 e/10 ml) in 2016 compared to 0.47 e/10 ml (95% CI: 0.16-0.78 e/10 ml) in 2012 (p < 0.05) (no baseline data). No district was highly endemic in 2016 compared to three at baseline and there was no significant difference in prevalence or intensity of infection by sex for both species. This survey illustrated the significant progress made in controlling schistosomiasis in Sierra Leone. The fact that prevalence and intensity of infection showed an increase from the 2010 level suggested a detrimental effect of missing MDA due to the Ebola toward schistosomiasis control. The national program needs to continue the treatment and adopt a comprehensive approach including water, hygiene, and sanitation measures to achieve control and elimination of schistosomiasis.

Integrating reproductive and child health services enables access to modern contraception in Sierra Leone

BACKGROUND

From mid-2015, reproductive and child health interventions were integrated into a routine 6-month contact point: vitamin A supplementation, nutrition counseling with the mother's participation in the preparation of a complementary food, and confidential family planning counseling with provision of modern forms of contraceptives. By mid-2017, these services had reached 28% of health facilities nationwide.

OBJECTIVE

To evaluate awareness and uptake of modern contraception and complementary feeding practices.

METHODS

All health facilities were visited, and the health worker "in-charge" were interviewed to ascertain their training status and supply chains. Within each catchment, community mothers of children 6 to 23 months of age were interviewed.

RESULTS

Interviews were conducted with 321 "in-charges" and 670 mothers. Advantages and different types of contraception were understood by 99.0% of mothers, and 52.7% reported they were utilizing depot injections, hormonal implants, or oral contraceptive pills (45.1%, 34.6%, and 20.6% of users, respectively). Uptake was higher among Christians (62.1%) versus Muslims (48.6%) and among those with secondary/tertiary (61.5%) or primary education (60.5%) versus no education (43.3%) (P < 0.005 and P < 0.05, respectively). Complementary feeding practices included minimal meal diversity, 49.2% (fed three or more of six food groups), and recommended minimal meal frequency appropriate for age, 52.6%. Health workers reported frequent stockouts of vitamin A capsules (8%), male condoms (1%), oral contraceptives (10%), depot injections (20%), and hormonal implants (30%).

CONCLUSION

In communities served by these integrated services, awareness and uptake of modern contraception exceeded national targets despite weak supply chains, and complementary feeding practices were favorable compared with the national survey.

Understanding the process of strengthening multi-sectoral efforts for anemia reduction: Qualitative findings from Sierra Leone and Uganda

Anemia is a significant global health problem, and progress to reduce it has been slow. A multi-sectoral, context-specific, and country-led approach is recommended to effectively address anemia, but there is limited documentation of how this has worked in practice. We present key findings and lessons learned from Sierra Leone and Uganda's experiences establishing national-level anemia coordination platforms. A longitudinal collective case study methodology was used, with in-depth interviews of National Anemia Working Group members in both countries; data was analyzed to distill the salient lessons learned across countries. Similar factors were identified in the 2 countries. Setting the agenda was an important first step, accomplished by using country-specific anemia-related data and obtaining multi-sectoral commitment. Establishment of a cohesive coordination structure provided an effective platform to prioritize and align anemia activities. Strong, committed leadership and representation of diverse stakeholders was essential to maintain the legitimacy of anemia efforts. The main barriers to the policy-making process included misalignment of sectoral mandates, differences in work cultures, as well as competing priorities and increased staff workload. Sierra Leone and Uganda's experiences contribute to the global evidence base for anemia coordination and planning at the national level, particularly around linking health and non-health sectors and developing multi-sectoral platforms. It remains to be seen how and to what extent resulting policies in Sierra Leone and Uganda will translate to implementation.

Progress on elimination of lymphatic filariasis in Sierra Leone

Background

A baseline survey in 2007–2008 found lymphatic filariasis (LF) to be endemic in Sierra Leone in all 14 districts and co-endemic with onchocerciasis in 12 districts. Mass drug administration (MDA) with ivermectin started in 2006 for onchocerciasis and was modified to add albendazole in 2008 to include LF treatment. In 2011, after three effective MDAs, a significant reduction in microfilaraemia (mf) prevalence and density was reported at the midterm assessment. After five MDAs, in 2013, mf prevalence and density were again measured as part of a pre-transmission assessment survey (pre-TAS) conducted per WHO guidelines.

Methods

For the pre-TAS survey, districts were paired to represent populations of one million for impact assessment. One sentinel site selected from baseline and one spot check site purposefully selected based upon local knowledge of patients with LF were surveyed per pair (two districts). At each site, 300 people over five years of age provided mid-night blood samples and mf prevalence and density were determined using thick blood film microscopy. Results are compared with baseline and midterm data.

Results

At pre-TAS the overall mf prevalence was 0.54% (95% CI: 0.36–0.81%), compared to 0.30% (95% CI: 0.19–0.47) at midterm and 2.6% (95% CI: 2.3–3.0%) at baseline. There was a higher, but non-significant, mf prevalence among males vs females. Eight districts (four pairs) had a prevalence of mf < 1% at all sites. Two pairs (four districts) had a prevalence of mf > 1% at one of the two sites: Koinadugu 0.98% (95% CI: 0.34–2.85%) and Bombali 2.67% (95% CI: 1.41–5.00%), and Kailahun 1.56% (95% CI: 0.72–3.36%) and Kenema 0% (95% CI: 0.00–1.21%).

Conclusions

Compared to baseline, there was a significant reduction of LF mf prevalence and density in the 12 districts co-endemic for LF and onchocerciasis after five annual LF MDAs. No statistically significant difference was seen in either measure compared to midterm. Eight of the 12 districts qualified for TAS. The other four districts that failed to qualify for TAS had historically high LF baseline prevalence and density and had regular cross-border movement of populations. These four districts needed to conduct two additional rounds of LF MDA before repeating the pre-TAS. The results showed that Sierra Leone continued to make progress towards the elimination of LF as a public health problem.

Impact of five annual rounds of mass drug administration with ivermectin on onchocerciasis in Sierra Leone

BACKGROUND

Onchocerciasis is endemic in 12 of the 14 health districts of Sierra Leone. Good treatment coverage of community-directed treatment with ivermectin was achieved between 2005 and 2009 after the 11-year civil conflict. Sentinel site surveys were conducted in 2010 to evaluate the impact of five annual rounds of ivermectin distribution.

METHODS

In total, 39 sentinel villages from hyper- and meso-endemic areas across the 12 endemic districts were surveyed using skin snips in 2010. Results were analyzed and compared with the baseline data from the same 39 villages.

RESULTS

The average microfilaridermia (MF) prevalence across 39 sentinel villages was 53.10% at baseline. The MF prevalence was higher in older age groups, with the lowest in the age group of 1-9 years (11.00%) and the highest in the age group of 40-49 years (82.31%). Overall mean MF density among the positives was 28.87 microfilariae (mf)/snip, increasing with age with the lowest in the age group of 1-9 years and the highest in the age group of 40-49 years. Males had higher MF prevalence and density than females. In 2010 after five rounds of mass drug administration, the overall MF prevalence decreased by 60.26% from 53.10% to 21.10%; the overall mean MF density among the positives decreased by 71.29% from 28.87 mf/snip to 8.29 mf/snip; and the overall mean MF density among all persons examined decreased by 88.58% from 15.33 mf/snip to 1.75 mf/snip. Ten of 12 endemic districts had > 50% reduction in MF prevalence. Eleven of 12 districts had ≥50% reduction in mean MF density among the positives.

CONCLUSIONS

A significant reduction of onchocerciasis MF prevalence and mean density was recorded in all 12 districts of Sierra Leone after five annual MDAs with effective treatment coverage. The results suggested that the onchocerciasis elimination programme in Sierra Leone was on course to reach the objective of eliminating onchocerciasis in the country by the year 2025. Annual MDA with ivermectin should continue in all 12 districts and further evaluations are needed across the country to assist the NTDP with programme decision making.

Association between sickle cell and β-thalassemia genes and hemoglobin concentration and anemia in children and non-pregnant women in Sierra Leone: ancillary analysis of data from Sierra Leone's 2013 National Micronutrient Survey

OBJECTIVE

By measuring the associations between the presence of sickle cell and β-thalassemia genes, we assessed the extent to which these hemoglobinopathies contribute to the high prevalence of anemia observed in preschool-aged children and women of reproductive age in Sierra Leone.

RESULTS

The prevalence of anemia was statistically significantly higher in children with homozygous sickle cell genes (HbSS) than in children with normal hemoglobin genes (HbAA or HbAC), but there was no difference in anemia prevalence in those with heterozygous sickle cell trait (HbAS or HbSC) compared with those with normal hemoglobin genes. In women, there was no difference in anemia prevalence by sickle cell status. In both children and women, there was no difference in the anemia prevalence for individuals with or without the β-thalassemia gene. For both sickle cell and β-thalassemia, there was no significant difference in hemoglobin concentrations by sickle cell or β-thalassemia status. Anemia prevalence was higher in children and women with homozygous sickle cell (HbSS). However, as the prevalence of HbSS children (5.4%) and women (1.6%) was quite small, it is unlikely that these hemoglobinopathies substantially contributed to the high anemia prevalence found in the 2013 national micronutrient survey.

Anemia, Micronutrient Deficiencies, and Malaria in Children and Women in Sierra Leone Prior to the Ebola Outbreak - Findings of a Cross-Sectional Study

To identify the factors associated with anemia and to document the severity of micronutrient deficiencies, malaria and inflammation, a nationally representative cross-sectional survey was conducted. A three-stage sampling procedure was used to randomly select children <5 years of age and adult women from households in two strata (urban and rural). Household and individual data were collected, and blood samples from children and women were used to measure the prevalence of malaria, inflammation, and deficiencies of iron, vitamin A, folate, and vitamin B12. 839 children and 945 non-pregnant women were included in the survey. In children, the prevalence rates of anemia (76.3%; 95% CI: 71.8, 80.4), malaria (52.6%; 95% CI: 46.0, 59.0), and acute and chronic inflammation (72.6%; 95% CI: 67.5, 77.1) were high. However, the prevalence of vitamin A deficiency (17.4%; 95% CI: 13.9, 21.6) was moderate, and the prevalence of iron deficiency (5.2%; 95% CI: 3.3, 8.1) and iron-deficiency anemia (3.8%; 95% CI: 2.5, 5.8) were low. Malaria and inflammation were associated with anemia, yet they explained only 25% of the population-attributable risk. In women, 44.8% (95% CI: 40.1, 49.5), 35.1% (95% CI: 30.1, 40.4), and 23.6% (95% CI: 20.4, 27.3) were affected by anemia, malaria, or inflammation, respectively. The prevalence rates of iron deficiency (8.3%; 95% CI: 6.2, 11.1), iron-deficiency anemia (6.1%; 95% CI: 4.4, 8.6), vitamin A deficiency (2.1%; 95% CI: 1.1, 3.1) and vitamin B12 deficiency (0.5%; 95% CI: 0.2, 1.4) were low, while folate deficiency was high (79.2%; 95% CI: 74.1, 83.5). Iron deficiency, malaria, and inflammation were significantly associated with anemia, but explained only 25% of cases of anemia. Anemia in children and women is a severe public health problem in Sierra Leone. Since malaria and inflammation only contributed to 25% of anemia, other causes of anemia, such as hemoglobinopathies, should also be explored.

Iodine Status of Women of Reproductive Age in Sierra Leone and Its Association with Household Coverage with Adequately Iodized Salt

Salt iodization programs are a public health success in tackling iodine deficiency. Yet, a large proportion of the world's population remains at risk for iodine deficiency. In a nationally representative cross-sectional survey in Sierra Leone, household salt samples and women's urine samples were quantitatively analyzed for iodine content. Salt was collected from 1123 households, and urine samples from 817 non-pregnant and 154 pregnant women. Household coverage with adequately iodized salt (≥15 mg/kg iodine) was 80.7%. The median urinary iodine concentration (UIC) of pregnant women was 175.8 µg/L and of non-pregnant women 190.8 µg/L. Women living in households with adequately iodized salt had higher median UIC (for pregnant women: 180.6 µg/L vs. 100.8 µg/L, respectively, p < 0.05; and for non-pregnant women: 211.3 µg/L vs. 97.8 µg/L, p < 0.001). Differences in UIC by residence, region, household wealth, and women's education were much smaller in women living in households with adequately iodized salt than in households without. Despite the high household coverage of iodized salt in Sierra Leone, it is important to reach the 20% of households not consuming adequately iodized salt. Salt iodization has the potential for increasing equity in iodine status even with the persistence of other risk factors for deficiency.

Integrating Vitamin A Supplementation at 6 months into the Expanded Program of Immunization in Sierra Leone

Since 2004, twice-yearly mass vitamin A supplementation (VAS) has equitably reached over 85% of children 6-59 months old in Sierra Leone. However infants who turn 6 months after the event may wait until they are 11 months old to receive their first dose. The effectiveness of integrating VAS at 6 months into the Expanded Program of Immunization (EPI) in a revised child health card was studied. Health facilities matched according to staff cadre and work load were assigned to provide either a 'mini package' of VAS and infant and young child feeding (IYCF), a 'full package' of VAS, IYCF and family planning (FP), or 'child health card' only. 400 neonates were enrolled into each group, caregivers given the new child health card and followed until they were 12 months old. More infants in the full: 74.5% and mini: 71.7% group received VAS between 6 and 7 months of age compared with the new CH card only group: 60.2% (p = 0.002, p < 0.001 respectively). FP commodities were provided to 44.5% of caregivers in the full compared with <2.5% in the mini and new child health card only groups (p < 0.0001). Integration of VAS within the EPI schedule achieved >60% coverage for infants between 6 and 7 months of age. Provision of FP and/or IYCF further improved coverage. Funding was provided by the Canadian Department of Foreign Affairs, Trade and Development who had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.

High coverage of vitamin A supplementation and measles vaccination during an integrated Maternal and Child Health Week in Sierra Leone

BACKGROUND

In May 2012, the twice-yearly Maternal and Child Health Week (MCHW) integrated vitamin A supplementation (VAS) and supplementary measles vaccination to reach all children 6-59 months in Sierra Leone. Following the MCHW, a post event coverage survey was conducted to validate VAS coverage and assess adverse events following immunization.

METHODS

Using the WHO Expanded Program on Immunization sampling methodology, 30 clusters were randomly selected using population proportionate to size sampling. Fourteen caregivers of children 6-59 months were interviewed per cluster for precision of ±5%. Responses were collected via mobile phones using EpiSurveyor.

RESULTS

Overall VAS and measles coverage was 91.9% and 91.6%, respectively, with no significant differences by age group, sex, religion or occupation. Major reasons given for not receiving VAS and measles vaccination were not knowing about the MCHW or being out of the area. Significantly more mild adverse events (fever, pain at injection site) were reported via the post event coverage survey (29.1%) than MCHW (0.01%) (p<0.0001).

CONCLUSION

The MCHW reached >90% of children in Sierra Leone with equitable coverage. Increased reporting of mild adverse events during the survey may be attributed to delayed onset after measles vaccination and/or direct inquiry from enumerators. Even mild adverse events following immunization requires strengthened reporting during and after vaccination campaigns.

Baseline health conditions in selected communities of northern Sierra Leone as revealed by the health impact assessment of a biofuel project

BACKGROUND

As biofuel projects may be associated with positive and negative effects on people's health and wellbeing, a health impact assessment was performed for the Addax Bioenergy Sierra Leone (ABSL) project. We present data from the baseline health survey, which will provide a point of departure for future monitoring and evaluation activities.

METHODS

In December 2010, a cross-sectional survey was carried out in eight potentially affected communities. A broad set of clinical and parasitological indicators were assessed using standardised, quality-controlled procedures, including anthropometry and prevalence of anaemia, Plasmodium falciparum and helminth infections.

RESULTS

Complete datasets were obtained from 1221 individuals of 194 households and eight schools. Of children aged <5 years (n=586), 41.8% were stunted, 23.2% were underweight and 4.8% were wasted. Very high prevalences of anaemia and P. falciparum were found in children aged 6-59 months (n=571; 86.1% and 74.0%, respectively). Overall, 73.7% of women of reproductive age (n=395) were anaemic. In school-aged children (n=240), 27.9% had light- to moderate-intensity hookworm infections, whereas Ascaris lumbricoides, Trichuris trichiura and Schistosoma mansoni were rare (<3% each).

CONCLUSIONS

The detailed description of the baseline health conditions, in combination with future health surveys, will deepen the understanding of how a biofuel project impacts on community health in a rural setting in sub-Saharan Africa.

Reemergence of chikungunya virus in Bo, Sierra Leone

We diagnosed 400 possible IgM-positive cases of chikungunya virus in Bo, Sierra Leone, during July 2012–January 2013 by using lateral flow immunoassays. Cases detected likely represent only a small fraction of total cases. Further laboratory testing is required to confirm this outbreak and characterize the virus.

Schistosoma mansoni infection after three years of mass drug administration in Sierra Leone

BACKGROUND

Schistosoma mansoni was moderately-highly endemic in the northeast of Sierra Leone. The national neglected tropical disease control program started mass drug administration (MDA) with praziquantel (PZQ) in six districts in 2009 targeting primary school children only. The effort was scaled-up to seven districts in 2010 targeting school aged children (SAC) and at-risk adults. A cross-sectional sentinel site survey was conducted in 2012 after three rounds of MDA to evaluate the impact of the national program.

METHODS

Twenty-six (26) sentinel sites were randomly selected from the baseline mapping survey sites stratified according to the baseline prevalence into high, moderate or low endemic category. Fifty (50) school children (25 males and 25 females) were randomly selected per site. Fresh stool samples were examined in the field using the Kato Katz technique. The results were compared with the baseline data.

RESULTS

Program coverage of 94.8%, 77.1% and 81.7% was reported in 2009, 2010 and 2011 respectively. Independent monitoring in 2011 showed program coverage of 83.9%, not significantly different from the reported result in the same year. The overall prevalence of S. mansoni was 16.3% (95% CI: 14.4-18.4%) and mean intensity was 18.98 epg (95% CI: 11.46-26.50 epg) in 2012, representing 67.2% and 85.9% reduction from the baseline respectively. The proportion of moderately and heavily infected children was 3.3% and 1.2%, a significant reduction from 18.2% and 8.8% at baseline respectively.

CONCLUSIONS

Sierra Leone has maintained effective MDA coverage with PZQ since 2009. Three rounds of MDA led to a significant reduction of S. mansoni infection in the country. In line with the significant progress made in controlling schistosomiasis, the national treatment strategy has been reviewed and MDA will be expanded to include school age children in low endemicity districts with the new national objective for the elimination of schistosomiasis. Sierra Leone is well on its way to eliminate schistosomiasis as a public health problem.

High and equitable mass vitamin A supplementation coverage in Sierra Leone: a post-event coverage survey

BACKGROUND

In Sierra Leone, children ages 6-59 months receive twice-yearly vitamin A supplementation (VAS) through Maternal and Child Health Week (MCHW) events. VAS coverage in 2011 was calculated using government tally sheets of vitamin A capsule distribution and outdated population projections from the 2004 census. We conducted a national post-event coverage (PEC) survey to validate coverage and inform strategies to reach universal coverage of VAS in Sierra Leone.

METHODOLOGY

Immediately following the November 2011 MCHW event, we conducted a national PEC survey by interviewing caregivers with children ages 6-59 months using a randomized 30X30 cluster design (N = 900). We also interviewed one health worker and one community health worker in each cluster to determine their knowledge about VAS (N = 60).

RESULTS

VAS coverage was 91.8% among children ages 6-59 months, which was lower than the 105.1% reported through tally sheets. Coverage was high and equitable among all districts and between age groups (98.5% for infants ages 6-11 months and 90.5% for children ages 12-59 months). Major reasons for not receiving VAS were that the child was out of the area (42.4%), the household was not visited by community health workers (28.0%), and the caretaker was not aware of the event (11.9%).

CONCLUSION

Twice-yearly delivery of VAS through MCHW events achieved consistently high and equitable coverage in Sierra Leone. Universal coverage may be achieved through continued focus on communication and targeted outreach to hard-to-reach areas during the MCHWs.

High level of Schistosoma mansoni infection in pre-school children in Sierra Leone highlights the need in targeting this age group for praziquantel treatment

BACKGROUND

Schistosomiasis and soil-transmitted helminth (STH) infections are endemic in Sierra Leone. The consequences of these diseases to pre-school children are well understood. The national control program currently does not target this group of children for schistosomiasis, while mass drug administration (MDA) has been performed six monthly for STHs in children 12-59 months of age since 2006.

METHODS

To assist the national decision on MDA strategy to control schistosomiasis and STH, three cross-sectional surveys were conducted in pre-school children in 2009-2011 as part of routine surveillance performed in different areas and in different phases of MDA, including known 'Hard to Reach' villages where consistently poor coverage results were seen in recent MDA. Thirty 4-5 year-old children were randomly selected per site and a stool sample from each child was examined by Kato-Katz thick smear. Pooled data were analyzed for schistosomiasis and separate sets of data were presented for STHs. In total 61 sites were surveyed and a total of 1803 children were examined.

RESULTS

The overall prevalence and intensity of Schistosoma mansoni was 11.2% (95% CI 9.7-12.8) and 33.5 epg (95% CI 19.7-47.3). Relatively high level of infection was found in Kono (35.4% and 102.9 epg), Tonkolili (30.4% and 142.3 epg) and Koinadugu (20.8% and 47.0 epg). There were 8.1% of children 4-5 years old moderately or heavily infected with S. mansoni. Overall level of STH infections were generally low, with hookworm 8.4-22.8%, Ascaris lumbricoides 0.2-17.2%, and Trichuris trichiura 0.9-2.6% in three surveys. However, prevalence of hookworm and A. lumbricoides was relatively high in those hard-to-reach villages even two months after MDA.

CONCLUSIONS

Relatively high levels of S. mansoni infections were found in children aged 4-5 years old in Sierra Leone, in line with geographical distribution of the disease observed in older children in the country. The results suggest that this group of children should not be neglected further in the schistosomiasis MDA and a global guideline is needed. Overall prevalence of STH infection was relatively low. Although there was no baseline data for direct comparison, it did show a marked reduction in STH infections, compared with historical data. However, relatively higher prevalence in hard-to-reach villages suggests the difficulty and quality of implementing MDA in such difficult locations, and more efforts and perhaps different delivery strategies are needed in these locations to increase the quality of MDA.

Mass drug administration significantly reduces infection of Schistosoma mansoni and hookworm in school children in the national control program in Sierra Leone

Background

The first-ever round of school-based mass drug administration (MDA) with praziquantel together with mebendazole targeting school-aged children in endemic districts was conducted in 2009 by the National Neglected Tropical Diseases Control Program. To evaluate the impact of the treatment regimen, a cross-sectional sentinel site survey was conducted 6 months post-MDA.

Methods

Fifteen sentinel schools from six highly endemic districts (according to data from national and pre-MDA surveys) with Schistosoma mansoni affecting over 50% of the population, and moderate to high prevalence of hookworms (> 20%). Approximately 30 children aged 9-14 years were selected from each school and stool samples (one per student) were examined by the Kato-Katz method.

Results

The overall prevalence (and intensity) in these sentinel sites pre-MDA of S. mansoni was 69.0% (170.8 epg), hookworm: 41.7% (71.7 epg), Ascaris lumbricoides: 1.8% and Trichuris trichiura: 3.8%. Six months post MDA, the findings were S. mansoni: 38.2% (47.3 epg) and hookworm: 14.5% (8.7 epg), representing a reduction from pre-MDA levels of 44.6% (65.2%) and 72.3% (87.9%) respectively. The proportion of children who were moderately or heavily infected with S. mansoni fell from 35.6% pre MDA to 9.9% post MDA.

Conclusions

Significant reduction in S. mansoni and hookworm infection was achieved by this first round MDA in school-going children in Sierra Leone. This reduction in infection burden can potentially contribute to a reduction of morbidity, such as anaemia, in these children.

Lymphatic filariasis mapping by immunochromatographic test cards and baseline microfilaria survey prior to mass drug administration in Sierra Leone

Background

National mapping of lymphatic filariasis (LF) was conducted using Immunochromatographic tests (ICT) in 2005 to determine endemicity and geographic spread of the disease. A baseline microfilaria survey was then conducted to determine LF prevalence and microfilaria intensity.

Methods

In 2005 1,982 persons of 15 years and over from 14 health districts were selected and fingertip blood samples were tested with ICT cards. In 2007-8 blood samples were taken between 10 p.m. and 2 a.m. and examined for microfilaria (mf) from 9,288 persons from 16 sentinel sites representing each district and 2 additional sites for districts with populations over 500,000 (Bo and Kenema).

Results

The overall LF prevalence by ICT cards was 21% (males 28%, females 15%). All districts had a prevalence of Wuchereria bancrofti antigen > 1%. Distribution of LF prevalence showed a strong spatial correlation pattern with high prevalence in a large area in the northeast gradually decreasing to a relatively low prevalence in the southwest coast. High prevalence was found in the northeast, Bombali (52%), Koinadugu (46%), Tonkolili (37%) and Kono (30%). Low prevalence was found in the southwest, Bonthe (3%) and Pujehun (4%). The mf prevalence was higher in the northeast: Bombali, 6.7%, Koinadugu 5.7%, Port Loko 4.4% and Kono 2.4%. Overall there was a significant difference in mf prevalence by gender: males 2.9%, females 1.8% (p = 0.0002) and within districts in Kailahun, Kono, Port Loko, Moyamba and Koinadugu (all p < 0.05). The mf prevalence was higher in people > 20 years (2.5%) than in people ≤ 20 years (1.7%) (p = 0.043). The overall arithmetic mean mf density was 50.30 mf/ml among mf-positive individuals and 1.19 mf/ml in the population examined which varied significantly between districts.

Conclusions

The ICT results showed that LF was endemic nationwide and that preventive chemotherapy (PCT) was justified across the country. Both the ICT and microfilaraemia surveys found that prevalence was greater in males than females. The increase in microfilaraemia prevalence by age was evident when grouped as ≤ 20 versus > 20 years demonstrating early exposure. Baseline LF microfilaria load will be used to monitor PCT program progress.

High coverage of mass drug administration for lymphatic filariasis in rural and non-rural settings in the Western Area, Sierra Leone

Background

Lymphatic filariasis elimination programs are based upon preventative chemotherapy annually in populations with prevalence more than or equal to 1%. The goal is to treat 80% of the eligible, at risk population yearly, for at least 5 years, in order to interrupt transmission and prevent children from becoming infected. This level of coverage has been a challenge in urban settings. Assessing the coverage in a rapidly growing urban/non-rural setting with inadequate population data is also problematic. In Sierra Leone, a 5-day preventative chemotherapy campaign was carried out in the Western Area including the capital: Freetown. An intensive, social mobilization strategy combined traditional and modern communication channels. To aid dissemination of appropriate information Frequently Asked Questions were developed and widely circulated. The population of the Western Area has grown faster than projected by the 2004 National Census due to the post-war settlement of internally displaced persons. As a reliable denominator was not available, independent monitoring was adapted and performed "in process" to aid program performance and "end process" to assess final coverage.

Results

In 5 days 1,104,407 eligible persons were treated. Using the projected population from the 2004 census this figure represented coverage of 116% in the Urban Western Area and 129% in the Rural Western Area. Independent monitors interviewed a total of 9,253 persons during the 2 End Process days representing 1% of the projected population. Of these, 85.8% recalled taking both ivermectin and albendazole (Urban: 85.2%, Rural: 87.1%). No serious adverse drug reactions were reported.

Conclusion

The paper presents the key elements of success of the social mobilization and implementation strategy and describes the independent monitoring used to estimate final coverage in this urban/non-rural setting where the current population size is uncertain. This implementation strategy and Independent Monitoring tool could be useful in similar, rapidly growing cities implementing lymphatic filariasis elimination programs.