Surveillance for lymphatic filariasis after stopping mass drug administration in endemic districts of Togo, 2010-2015.

BACKGROUND: Togo is a country previously endemic for lymphatic filariasis (LF). In 2010, following nine years of mass drug administration (MDA) for LF, the country established a post-treatment surveillance (PTS) system. We present here the results of these PTS activities, carried out from 2010 to 2015, as well as the findings of follow-up investigations in 2016 to confirm the absence of infection in previously infected individuals. METHODS: The routine surveillance established in 2010 consisted of a network of 47 laboratories, which searched for Wuchereria bancrofti microfilaria on nocturnal blood smears collected for malaria diagnosis and an additional network of 20 peripheral health facilities, which collected dried blood spots and tested them for Og4C3 antigen. Two transmission assessment surveys (TAS) were also undertaken, as recommended by WHO, in 2012 and 2015. Any positive case identified through any surveillance activity was immediately retested by nocturnal smear and confirmed cases were immediately investigated by screening family members and neighboring household members. In 2016, 32 of the 40 positive cases detected during TAS or laboratory and health facility network activities were traced and whether confirmed positive by nocturnal smear or not were tested again simultaneously by filariasis test strip (FTS), Og4C3 and a nocturnal blood smear to rule out any active infection. RESULTS: From 2010 to 2015, the laboratory network identified one microfilaria-positive individual (0.0% of 26,584 persons tested) and the peripheral health facility network detected 19 Og4C3-positive individuals (0.28% of 6788 persons tested). All 19 Og4C3 cases were negative for microfilaremia by nocturnal blood smear. In the 2012 and 2015 TAS, thirteen and six ICT/FTS positive cases, respectively, were identified, which were significantly below the critical cut-off (18-20 cases) across all evaluation units. Three of the six ICT/FTS-positive cases from the 2015 TAS were positive by nocturnal smear; immediate investigation identified one additional microfilaria-positive individual. Epidemiological investigation revealed that four of the five cases of microfilaremia were imported from another country in the region. In 2016, 32 of the 40 positive cases detected by at least one test during all surveillance activities were traced: four (12.5%) individuals were still positive by FTS but all 32 individuals were negative for microfilaremia and Og4C3 antigen. CONCLUSION: The results of post-treatment surveillance in Togo have demonstrated that W. bancrofti filariasis is no longer of public health concern in Togo, more than six years after stopping MDA. Every possible effort should be made to maintain surveillance in order to promptly detect any resurgence and preserve this achievement.

Transitioning from river blindness control to elimination: steps toward stopping treatment.

The transition from onchocerciasis control to elimination requires country programmes to rethink their approach to a variety of activities as they move from addressing morbidity to addressing transmission of the parasite. Although the 2016 WHO guidelines provide extensive recommendations, it was beyond the scope of the document to provide guidance on all aspects of the transition. This paper will discuss some of the important issues that programmes are grappling with as they transition to elimination and provide some potential approaches that programmes can use to address them. Although there are some data to support some aspects of the suggested approaches, operational research will be needed to generate data to support these approaches further and to determine how programmes could best tailor them to their own unique epidemiological challenges. Good communication between the national programmes and the broader global programme will facilitate the clear articulation of programmatic challenges and the development of the evidence to support programme decision-making.

The role of the NGDO Coordination Group for the Elimination of Onchocerciasis.

The NGDO Coordination Group for the Control of Onchocerciasis was launched in 1992, and with the paradigm shift from control of disease to elimination of onchocerciasis transmission, the Group shifted its orientation to that new paradigm in 2013. It also changed its name, replacing 'control' with 'elimination.' In doing so, the Group has repositioned itself to build on the successes of the past to finish the job it began over 25 years ago.

Onchocerciasis: shifting the target from control to elimination requires a new first-step-elimination mapping.

The meaning of 'mapping' in relation to onchocerciasis has changed at least three times over the past 50 years as the programmatic goals and the assessment tools have changed. With the current goal being global elimination of Onchocerca volvulus (OV), all areas where OV might currently be transmitted and where mass drug administration (MDA) with ivermectin treatment has not been delivered previously must now be identified by careful, detailed 'elimination mapping' as either OV endemic or not, so that appropriate programmatic targets can be established. New tools and strategies for such elimination mapping have become available, though ongoing studies must still be completed to define agreed upon optimal diagnostic evaluation units, sampling strategies and serologic tools. With detailed guidance and technical support from the World Health Organization and with implementation and financial support from their global partners, the OV-endemic countries of Africa can soon complete their elimination mapping and then continue with MDA programmes to progressively achieve the same success in OV elimination as that already achieved by the growing list of formerly OV-endemic countries in the Americas.

Cross-border issues: an important component of onchocerciasis elimination programmes.

Endemic areas that involve national or local borders present an important challenge to the success of elimination of onchocerciasis; such cross-border endemic foci require special attention to ensure that programme activities are unified. It is vital that national programmes and the committees responsible for the oversight of progress towards elimination are aware and address such issues in their current planning and programmatic activities. Although international borders that intersect endemic zones present the biggest challenge, intracountry borders (such as between administrative districts or loiasis endemic and non-loiasis areas) can also pose problems. The recent change in the onchocerciasis programme from disease control to transmission interruption, given the historical lack of treatment in hypo-endemic areas, may have increased the already relatively high number of cross-national scenarios in Africa. It is vital that all national programmes address the issue of any cross-border endemic areas as a matter of urgency and include this important issue in their elimination plans.

Molecular xenomonitoring for post-validation surveillance of lymphatic filariasis in Togo: no evidence for active transmission.

BACKGROUND: Lymphatic filariasis (LF) is a mosquito-borne filarial disease targeted for elimination by the year 2020. The Republic of Togo undertook mass treatment of entire endemic communities from 2000 to 2009 to eliminate the transmission of the disease and is currently the first sub-Saharan African country to be validated by WHO for the elimination of LF as a public health problem. However, post-validation surveillance activities are required to ensure the gains achieved are sustained. This survey assessed the mosquito vectors of the disease and determined the presence of infection in these vectors, testing the hypothesis that transmission has already been interrupted in Togo. METHOD: Mosquitoes were collected from 37 villages located in three districts in one of four evaluation units in the country. In each district, 30 villages were selected based on probability proportionate to size; eight villages (including one of the 30 villages already selected) where microfilaremia-positive cases had been identified during post-treatment surveillance activities were intentionally sampled. Mosquitoes were collected using pyrethrum spray collections (PSC) in households randomly selected in all villages for five months. In the purposefully selected communities, mosquitoes were also collected using human landing collections (HLC) and exit traps (ET). Collected mosquitoes were identified morphologically, and the identification of Wuchereria bancrofti DNA in the mosquitoes was based on the pool screening method, using the LAMP assay. RESULTS: A total of 15,539 mosquitoes were collected during the study. Anopheles gambiae (72.6%) was the predominant LF vector collected using PSC. Pool screen analysis of 9191 An. gambiae in 629 pools revealed no mosquitoes infected with W. bancrofti (0%; CI: 0-0.021). CONCLUSIONS: These results confirm the findings of epidemiological transmission assessment surveys conducted in 2012 and 2015, which demonstrated the absence of LF transmission in Togo. The challenges of implementing molecular xenomonitoring are further discussed.

Cross-border collaboration for neglected tropical disease efforts-Lessons learned from onchocerciasis control and elimination in the Mano River Union (West Africa).

Diseases don't respect borders, so efforts to control and eliminate diseases must also be flexible and adaptable enough to effectively reach the populations that live in the areas around national frontiers. Onchocerciasis, commonly known as river blindness is a tropical disease that has historically affected millions of people in 35 countries in Africa and Latin America. In Africa, programs and partnerships to address river blindness through mass drug administration have been active for more than 25 years. While in many cases the disease is found in isolated foci that fall entirely within national boundaries, the geographic scope of many affected areas crosses country borders. National river blindness programs are the responsibility of each nation's Ministry of Health, so in cross-border situations there is a need for effective country-country collaboration. Cross-border collaboration for onchocerciasis control efforts in the countries of the Mano River Basin illustrates the positive impact of a creative model, and offers lessons for expanded application for onchocerciasis elimination as well as other neglected tropical disease (NTD) control and elimination programs.

Final program evaluation methods and results of a National Lymphedema Management Program in Togo, West Africa.

In order to eliminate Lymphatic Filariasis (LF) as a public health problem, the World Health Assembly recommends an approach which includes interruption of transmission of infection and the alleviation of morbidity. In 2000, the Togolese National Program to Eliminate Lymphatic Filariasis (PNELF) started the annual mass drug administrations and in 2007, the program added a morbidity component for the management of lymphedema. This manuscript describes the methods of an evaluation aimed at assessing the strengths and weaknesses of the Togolese National Lymphedema Morbidity Program. The evaluation was conducted through in-depth interviews with stakeholders at each programmatic level. Interviews focused on message dissemination, health provider training, patient self-care practices, social dynamics, and program impact. The evaluation demonstrated that the program strengths include the standardization and in-depth training of health staff, dissemination of the program's treatment message, a positive change in the community's perception of lymphedema, and successful patient recruitment and training in care techniques. The lessons learned from this evaluation helped to improve Togo's program, but may also provide guidance and strategies for other countries desiring to develop a morbidity program. The methods of program evaluation described in this paper can serve as a model for monitoring components of other decentralized national health programs in low resource settings.

Ongoing surveillance for lymphatic filariasis in Togo: assessment of alternatives and nationwide reassessment of transmission status.

Tremendous progress has been made towards the goal of global elimination of lymphatic filariasis (LF) transmission by 2020. The number of endemic countries reducing LF transmission through mass drug administration continues to increase, and therefore, the need for effective post-intervention surveillance also continues to increase. Togo is the first sub-Saharan African country to implement LF surveillance, and it has 6 years of experience with this passive surveillance system. We herein report the results of a recent evaluation of the Togolese LF surveillance system, including an evaluation of blood donors as a surveillance population, and provide updated results of ongoing surveillance, including expansion in remote areas. Since implementation of LF surveillance in 2006, only three cases of positive Wuchereria bancrofti filaremia have been detected, suggesting that interruption of transmission has been sustained. Given the impracticality of validating the surveillance system in the absence of ongoing transmission, we confirmed the lack of transmission through a nationwide reassessment survey.

It is possible: availability of lymphedema case management in each health facility in Togo. Program description, evaluation, and lessons learned.

Lymphatic filariasis (LF) is a vector-borne parasitic disease that can clinically manifest as disabling lymphedema. Although the LF elimination program aims to reduce disability and to interrupt transmission, there has been a scarcity of disease morbidity management programs, particularly on a national scale. This report describes the implementation of the first nationwide LF lymphedema management program. The program, which was initiated in Togo in 2007, focuses on patient behavioral change. Its goal is two-fold: to achieve a sustainable program on a national-scale, and to serve as a model for other countries. The program has five major components: 1) train at least one health staff in lymphedema care in each health facility in Togo; 2) inform people with a swollen leg that care is available at their dispensary; 3) train patients on self-care; 4) provide a support system to motivate patients to continue self-care by training community health workers or family members and providing in home follow-up; and 5) integrate lymphedema management into the curriculum for medical staff. The program achieved the inclusion of lymphedema management in the routine healthcare package. The evaluation after three years estimated that 79% of persons with a swollen leg in Togo were enrolled in the program. The adherence rate to the proposed World Health Organization treatment of washing, exercise, and leg elevation was more than 70% after three years of the program, resulting in a stabilization of the lymphedema stage and a slight decrease in reported acute attacks among program participants. Health staff and patients consider the program successful in reaching and educating the patients. After the external funding ended, the morbidity management program is maintained through routine Ministry of Health activities.

Surveillance of the efficacy of artemether-lumefantrine and artesunate-amodiaquine for the treatment of uncomplicated Plasmodium falciparum among children under five in Togo, 2005-2009.

BACKGROUND: Malaria remains a major public health problem in Togo. The national malaria control programme in Togo changed the anti-malarial treatment policy from monotherapy to artemisinin combination therapy in 2004. This study reports the results of therapeutic efficacy studies conducted on artemether-lumefantrine and artesunate-amodiaquine for the treatment of uncomplicated Plasmodium falciparum malaria in Togo, between 2005 and 2009. METHODS: Children between 6 and 59 months of age, who were symptomatically infected with P. falciparum, were treated with either artemether-lumefantrine or artesunate-amodiaquine. The primary end-point was the 28-day cure rate, PCR-corrected for reinfection and recrudescence. Studies were conducted according to the standardized WHO protocol for the assessment of the efficacy of anti-malarial treatment. Differences between categorical data were compared using the chi-square test or the Fisher's exact test where cell counts were ≤ 5. Differences in continuous data were compared using a t-test. RESULTS: A total of 16 studies were conducted in five sentinel sites, with 459, 505 and 332 children included in 2005, 2007 and 2009, respectively. The PCR-corrected 28-day cure rates using the per-protocol analysis were between 96%-100% for artemether-lumefantrine and 94%-100% for artesunate-amodiaquine. CONCLUSIONS: Both formulations of artemisinin-based combination therapy were effective over time and no severe adverse events related to the treatment were reported during the studies.

A laboratory-based surveillance system for Wuchereria bancrofti in Togo: a practical model for resource-poor settings.

One goal of the Global Program to Eliminate Lymphatic Filariasis (GAELF) is interruption of disease transmission through annual mass drug administration (MDA) in areas where LF prevalence is greater than 1%. After MDAs are completed, the World Health Organization (WHO) recommends a period of passive surveillance before final certification of LF elimination is achieved. Guidelines for such a surveillance system have yet to be developed. This paper describes a surveillance system launched in Togo in 2006. The system uses existing laboratories with technicians on call at night who, among other activities, prepare nocturnal thick blood smears for malaria diagnosis that can also be used for LF diagnosis. During its first 2 years (2006-2007), the system provided geographically disperse sampling nationwide, and 1 of 750 people residing in Togo was tested. Over the same period, the system detected two cases of LF, both from areas previously considered non-endemic. This system could be a cost-effective, sustainable model for WHO-mandated passive surveillance after cessation of MDA.

Rapid scale-up of long-lasting insecticide-treated bed nets through integration into the national immunization program during child health week in Togo, 2004.

In December 2004, Togo was the first country to conduct a nationwide free insecticide-treated net (ITN) distribution as part of its National Integrated Child Health Campaign. Community-based cross-sectional surveys were conducted one and nine months post-campaign as part of a multidisciplinary evaluation of the nationwide distribution of ITNs to children 9-59 months of age to evaluate ITN ownership, equity, and use. Our results demonstrated that at one month post-campaign, 93.1% of all eligible children received an ITN. Household ITN ownership and equity increased significantly post-campaign. Nine months post-campaign, 78.6% of households with a child eligible to participate in the campaign retained at least one campaign net. Use by eligible children was 43.5% at one month post-campaign (during the dry season) and 52.9% at nine months post-campaign (during the rainy season). Household ownership of at least one ITN increased from 8.0% pre-campaign to 62.5% one month post-campaign. Together, these findings demonstrate that in this setting, increased household ITN ownership, equity, and retention can be achieved on a national scale through free ITN distribution during an integrated campaign.

Impact of mass distribution of free long-lasting insecticidal nets on childhood malaria morbidity: the Togo National Integrated Child Health Campaign.

BACKGROUND: An evaluation of the short-term impact on childhood malaria morbidity of mass distribution of free long-lasting insecticidal nets (LLINs) to households with children aged 9-59 months as part of the Togo National Integrated Child Health Campaign. METHODS: The prevalence of anaemia and malaria in children aged zero to 59 months was measured during two cross-sectional household cluster-sample surveys conducted during the peak malaria transmission, three months before (Sept 2004, n=2521) and nine months after the campaign (Sept 2005, n=2813) in three districts representative of Togo's three epidemiological malaria transmission regions: southern tropical coastal plains (Yoto), central fertile highlands (Ogou) and northern semi-arid savannah (Tone). RESULTS: In households with children<5 years of age, insecticide-treated net (ITN) ownership increased from <1% to >65% in all 3 districts. Reported ITN use by children during the previous night was 35.9%, 43.8% and 80.6% in Yoto, Ogou and Tone, respectively. Rainfall patterns were comparable in both years. The overall prevalence of moderate to severe anaemia (Hb<8.0 g/dL) was reduced by 28% (prevalence ratio [PR] 0.72, 95% CI 0.62-0.84) and mean haemoglobin was increased by 0.35 g/dL (95% CI 0.25-0.45).The effect was predominantly seen in children aged 18-59 months and in the two southern districts: PR (95% CI) for moderate to severe anaemia and clinical malaria: Yoto 0.62 (0.44-0.88) and 0.49 (0.35-0.75); Ogou 0.54 (0.37-0.79) and 0.85 (0.57-1.27), respectively. Similar reductions occurred in children<18 months in Ogou, but not in Yoto. No effect was seen in the semi-arid northern district despite a high malaria burden and ITN coverage. CONCLUSIONS: A marked reduction in childhood malaria associated morbidity was observed in the year following mass distribution of free LLINs in two of the three districts in Togo. Sub-national level impact evaluations will contribute to a better understanding of the impact of expanding national malaria control efforts.

Collecting baseline information for national morbidity alleviation programs: different methods to estimate lymphatic filariasis morbidity prevalence.

The lymphatic filariasis elimination program aims not only to stop transmission, but also to alleviate morbidity. Although geographically limited morbidity projects exist, few have been implemented nationally. For advocacy and planning, the program coordinators need prevalence estimates that are currently rarely available. This article compares several approaches to estimate morbidity prevalence: (1) data routinely collected during mapping or sentinel site activities; (2) data collected during drug coverage surveys; and (3) alternative surveys. Data were collected in Plateau and Nasarawa States in Nigeria and in 6 districts in Togo. In both settings, we found that questionnaires seem to underestimate the morbidity prevalence compared with existing information collected through clinical examination. We suggest that program managers use the latter for advocacy and planning, but if not available, questionnaires to estimate morbidity prevalence can be added to existing surveys. Even though such data will most likely underestimate the real burden of disease, they can be useful in resource-limited settings.

Use of handheld computers with global positioning systems for probability sampling and data entry in household surveys.

We introduce an innovative method that uses personal digital assistants (PDAs) equipped with global positioning system (GPS) units in household surveys to select a probability-based sample and perform PDA-based interviews. Our approach uses PDAs with GPS to rapidly map all households in selected areas, choose a random sample, and navigate back to the sampled households to conduct an interview. We present recent field experience in two large-scale nationally representative household surveys to assess insecticide-treated bed net coverage as part of malaria control efforts in Africa. The successful application of this method resulted in statistically valid samples; quality-controlled data entry; and rapid aggregation, analyses, and availability of preliminary results within days of completing the field work. We propose this method as an alternative to the Expanded Program on Immunization cluster sample method when a fast, statistically valid survey is required in an environment with little census information at the enumeration area level.