Abstract An essential component in achieving accepted successful elimination of a disease or a pathogen involves the acquisition of quality-assured (QA) data that ultimately define the absence of infection or transmission in previously endemic areas. The acquisition of these essential data, in the case of onchocerciasis elimination, requires strong laboratory support for both testing and continuing evaluation/validation of the tools used for the required diagnostic and epidemiology procedures. There is also a need for standardization of the laboratory-based and field-based assays used across the onchocerciasis-endemic countries as well as continuing technical, fiscal and logistical support for laboratory activities. To achieve these needs, it is proposed to build on the existing onchocerciasis programme laboratory activities in the endemic areas by expanding these to include additional laboratories as referral services organized on a regional basis to support the needs of endemic countries. Included in these plans are the development of quality assurance mechanisms, supply chain procedures and standardization of protocols for the basic assays needed for both national onchocerciasis elimination programme surveys and supporting research activities. Such an entity could then include quality-assured testing for other neglected tropical diseases. Testing, Laboratory, Onchocerciasis, Elimination, Africa, QA, Network Introduction Recent evidence has shown that elimination of transmission of onchocerciasis in Africa is possible using mass treatment with ivermectin alone.1–3 In response to this understanding, the WHO has published new guidelines for verification of elimination of onchocerciasis.4 These guidelines require the use of new, more rigorous laboratory diagnostic tools to determine whether or not transmission has truly been interrupted. As countries begin to transition from control to elimination of onchocerciasis, national programmes have begun to focus on the diagnostic and laboratory needs required to safely make decisions to stop treatment and to ensure that recrudescence does not occur. Unlike other neglected tropical disease (NTD) elimination programmes, there is as yet no rapid, point-of-care diagnostic test (a point-of-use [POU] test), such as the lymphatic filariasis (LF) ‘filarial test strip’, for monitoring onchocerciasis, nor is there a suitable clinical endpoint indicator, such as the absence of trachomatous follicular inflammation for trachoma, that can be used for the decision to stop treatment. Instead, the ‘stopping’ decision for onchocerciasis currently incorporates two laboratory-based assays, namely, the ELISA for detection of Onchocerca volvulus 16 (OV16) antibody in children and PCR for O-150 in the Simulium blackfly vector. It should also be noted in relation to the current lack of a POU test for onchocerciasis that it is very much hoped that a usable rapid diagnostic test (RDT) for field testing with OV16 will soon be available. Such a rapid test is essential given the enormity of the amount of programmatic testing that is probably needed as onchocerciasis programme mapping rolls out; however, a new RDT will still need to be regularly validated by comparison with ELISA-based testing to ensure its activity in detecting the presence of OV16 antibody. Laboratories with the potential capacity to conduct these tests currently exist in a number of endemic countries, although most do not have long-standing experience with the specific tests being used and many may lack the standard quality assurances needed to ensure continuing accurate diagnosis. In addition, many labs are probably not currently prepared to take on the added workload required to perform the volume of work that will be required as onchocerciasis elimination efforts increase. For these reasons, it is important that a system is developed that can ensure not only quality of work and standardized diagnostic tools, but also support the availability of laboratory activities (financial, human, etc.) when the programmatic need arises. In this commentary we discuss the needs for specialized laboratory support for onchocerciasis in Africa. While lab services are not currently required for many of the other NTDs, these are likely to be needed in the future for diseases such as LF and soil-transmitted helminths, particularly as more sensitive tools become essential for confirmation of the breaking of transmission and other indicators of success in NTDs. Background Onchocerciasis is a filarial infection that is found in three regions of the world: Africa, Latin America and the Arabian Peninsula (Yemen), with most of the disease (99%) actually found in Africa. For more than 40 years the focus of interventions targeting the disease has primarily been on preventing morbidity, originally through vector management and for the last 30 years more commonly via mass treatment with ivermectin, donated by MSD, also known as Merck & Co., Inc., Kenilworth, NJ, USA. In recent years, the programmatic goals have moved from controlling the development of disease in humans (i.e., morbidity reduction) to targeting the complete elimination of parasite transmission.2,3 With this shift from control to elimination, there is now a major need for more technical support from quality-assured testing carried out in laboratories, importantly those within the African continent. However, it must be noted that laboratory activities for onchocerciasis have been established and supported for more than 10 years in specific sites in Africa by both the now closed African Program for Onchocerciasis Control (APOC) and by the Carter Center (Atlanta, GA, USA). Laboratories in Burkina Faso, Ethiopia, Nigeria, Uganda, Sudan and elsewhere have led the way in providing onchocerciasis programme support and provide a firm basis for the expanded network proposed in this present commentary. The methods that instruct on the appropriate collection of samples for testing in NTD programmes are driven by official WHO guidelines that define the steps required to ultimately define successful elimination. These include instructions that define the appropriate sampling timelines, the necessary sample sizes and the appropriate populations to be tested. An important component of developing a strong, efficient laboratory system and also in maintaining effective quality-assured RDTs for use in fields surveys is understanding and managing the volume of samples for testing that will be needed by country programmes; samples will need to be processed in a timely manner to allow for programmatic decision making and scheduling. Thus forecasting laboratory needs by country and by region is an important management component in developing and maintaining this laboratory network, and is vital to having a successful and efficient support system. Major principles The four major principles that will need to be followed in the proposed expanded laboratory network are ensuring the use of standard protocols, maintaining an appropriate quality assurance (QA) system, ensuring a laboratory supply chain system and establishing and maintaining a laboratory network communication system for sharing of experiences, protocols and appropriate data linking. Standard protocols The primary tools for epidemiological assessment of human onchocerciasis in the past have been either clinical or parasitological, and parasitological or molecular (presence of DNA) in the vector stage.5 Under the present guidelines from the WHO for onchocerciasis,4 the two current tests required for onchocerciasis programme monitoring and evaluation and eliminations are the detection of circulating onchocerciasis-specific antibody (currently immunoglobulin G4 [IgG4] antibody to OV16 antigen) in residents and the presence of O. volvulus DNA in the vector, Simulium sp. Up-to-date and standard protocols for these two assays, or any new approaches that might be added to the guidelines, need to be standardized and unified across the laboratory network. Quality assurance The second principle that the network will need to follow relates to QA. It is vital to the success of an elimination programme that the results used to define this success be of acceptable quality (i.e., are appropriately tested [by the recommended procedure]), be of high quality, are reproducible and are statistically appropriate; this will be an essential expectation of the wider public health and medical community when they are presented with the announcement of any success. The universal acceptance of any defined elimination success depends in large part on quality-assured laboratory-derived data and thus the support of a strong laboratory quality assurance system. To date, much of the data used in NTD programmes are based on laboratory work that has been carried out in research laboratories, sites that are not always following the independent quality-assured diagnostic protocols that are standard in hospital systems throughout the developed world; approved clinical laboratories follow College of American Pathologists regulations in the USA and Clinical Pathology Accreditation regulations in the UK. This is not to infer that data produced to date in research laboratories are necessarily not valid or of high quality, only that they are not generally backed by a robust QA programme. The establishment of a QA system, such as that discussed below, will ensure that the laboratories in the NTD network are producing results of high value and are believable. Ensuring that the results that are to be used to make important programmatic decisions in the progress towards elimination of onchocerciasis and the actual definition of elimination of onchocerciasis itself are of high quality ensures that the final success is unquestioned. The goal of any analytical laboratory QA/quality control (QC) programme is to guarantee the production of precise and accurate analytical data.6 Quality assurance involves the planned and systematic actions necessary to provide confidence in each result being produced by a laboratory and is a standard requirement of any valid medical network. A QA/QC programme can be seen as having two major components (Figure 1): QA—the system that ensures that the entire analytical process is operating within acceptable limits; there are a number of steps and components involved—and QC—the mechanisms put in place to detect non-conforming method performance. Figure 1. View largeDownload slide Quality assurance (QA) and quality control (QC) components. Figure 1. View largeDownload slide Quality assurance (QA) and quality control (QC) components. Fundamental to having a QA system in place is the practice of having standard operating procedures (SOPs) for each laboratory method or procedure currently being used, and these must be clearly and regularly documented as well as periodically reviewed and updated. Each active staff member in the laboratory must meet performance criteria and must be trained in the specific tests under consideration. The equipment must be reliable and well maintained (log books of test use, any problems, servicing activities, etc.); calibration of equipment also needs to be carried out on a regular basis. It is important that there is adherence to the regular use of appropriate analytical standard reference material, both externally provided samples and internal reference material. These actions should always be documented and thus traceable for comparison across programme laboratories in the NTD network. Optimally an annual review of the QC results should be carried out; this will ensure standardization across the NTD programme laboratories and allow for the detection of any erroneous trends—the use of blank samples and spiked samples can help in assuring QC. It is also important that the laboratories constantly address the question of comparability and standardization through the use of blank samples and duplicate runs, with 10% often used as a guideline. At least one standard reference material should be analysed with each set of samples, with samples run with a standard reference material that falls outside the acceptable range always reanalysed. Sample spiking is used to verify the accuracy of tests, especially those where samples have been subjected to extensive handling, transport, etc., or where the robustness of the sample may be in question. All such tests and QC activities should be recorded. It can be seen from the range of recommendations listed above that implementation of QA systems is both time consuming and expensive, but they are essential to the goal of elimination and the complete acceptance of success by the medical community as a whole. The laboratories in the support network being envisaged here for onchocerciasis/NTD programme support will in all likelihood be involved in the sharing of QA samples between one or more laboratories within the network. This will be important to ensure that the data used to describe and define successful elimination is uniform across the programme countries. An additional value of this sharing of samples is that it will encourage and underscore the vital role that the laboratories and the data they produce have in the overall elimination effort. Implementation of laboratory QA systems will also assist individual laboratories in developing their overall laboratory standards and capabilities through their experiences, and learning as they develop and contribute to the onchocerciasis programme. Laboratory supply chain One of the major challenges in maintaining diagnostic laboratories in Africa is maintaining the supply of reagents and equipment in a timely manner; indeed, this also applies to research-focused laboratory units. Almost all the reagents needed for the network will, in all likelihood, come from external sources, usually from supply companies in Europe or the USA, and in the case of specially prepared reagents, from specialized research laboratories or suppliers. It will be important to establish a system whereby the supplies needed by a country can be provided in a timely manner. This will in all likelihood be greatly assisted by developing the overall plan and test forecast for each country’s monitoring and evaluation activities—information that can be provided by each country through their national onchocerciasis elimination committees. It is also vital that, wherever possible, reagents originate from a single source and thus reduce the possibility of variations in results due to quality and functional differences in reagents. It will be important, as these laboratories are located in tropical zones, to accommodate the likely need for a ‘cold chain’ in many instances. Network communication system Communication and mutual awareness are central to maintaining such a network, especially to ensure that country participants gain the most value from the network. In today’s world there are a number of different means of establishing a communication network; however, it is important to employ a system that achieves the specific needs of the programme, such as sharing of experiences, harmonized protocols and requesting reagents. It is recognized that the sharing of data needs to be done appropriately, with due respect to country ownership, state of validation and other requirements that accompany the sharing and presentation of data. It is important that guidelines for data distribution be established by each country and the appropriate international agencies (e.g., Expanded Special Project on the Elimination of Neglected Tropical Diseases [ESPEN], WHO, Mectizan Donation Programme, Neglected Tropical Diseases Support Center and others). Reference material Vital to ensuring quality assurance in any laboratory network is the availability of both standard reference materials and supportive oversight through regular monitoring. These essentials also need to be supported by a strong information system that provides technical support and technical information where and when needed. The concept of the existence of a reference laboratory is often discussed in the context of this type of network, and certainly reference materials for standardization, as well as laboratory and diagnostic experts being available for consultation, are definitely needed in the system. However, in the interest of developing strong dependable laboratories in endemic regions, it is proposed that each laboratory in the network acts as a ‘referral centre’ rather than a ‘reference laboratory’ for their respective region, with the standardization component coming from the use of common material and standard samples. A focus on onchocerciasis elimination The laboratory needs for the monitoring and evaluation of endemic countries’ programme efforts to eliminate onchocerciasis have essentially been defined by the WHO to require two major assessments: the presence, or absence, of antibodies to onchocercal antigen (currently OV16) in the human population in endemic areas, especially the young residents in a target population. This assessment is carried out by an ELISA technique, and hopefully incorporating suitable RDTs in the future (QA for the latter is still carried out by comparing RDT findings with ELISA results). It should be noted that both of these tests for onchocerciasis are still being further developed by researchers as they seek more usable and comparable assays needed for uniformity across the WHO onchocerciasis programme endemic areas. The other basic technique needed for onchocerciasis programme evaluation is PCR, which is used for measuring the parasitic status of the vectors from onchocerciasis infection transmission sites; the detection of the presence of Onchocerca L3 molecular components (e.g., O-150) indicates the presence of infection in these Simulium vectors.5 Although older techniques (Figure 2), such as parasitological assessment of skin snips (microbiopsies), for epidemiological questions are still used by some programmes, often as confirmatory tests, such tests are not now generally accepted for programmatic use.5 Figure 2. View largeDownload slide The range of laboratory tests currently used in onchocerciasis elimination programmes. Figure 2. View largeDownload slide The range of laboratory tests currently used in onchocerciasis elimination programmes. Inclusion in an expanded laboratory network (ELN) It is likely that the number of laboratories involved in supporting national onchocerciasis programmes will develop over a number of years, influenced by the needs of each country and the location of suitable laboratories. As mentioned above, there are already laboratories that function in this role, and it is expected that in the initial expansion some five or six new laboratories will be supported to form an ELN. This expansion will be driven primarily by the needs of different regions of endemicity in Africa as well the capabilities of laboratories to participate. The approach that is currently proposed for the ELN to become a strong functional laboratory network across Africa is to first seek laboratories based on regional needs and evaluate their capabilities and desire to be part of such a network, including a willingness to focus on NTDs. It is planned to focus on supporting NTD elimination programmes, and specifically the needs of the onchocerciasis programme. However, there is the expectation that other NTDs will be included in the near future. The laboratories currently being considered for the network are selected so as to adequately cover the distribution of the endemic disease across Africa and the Yemeni focus. The potential regions (Figure 3) are all where there are known laboratories that could, with assistance (training, implementation of a QA programme, equipment enhancement, etc.), act as support laboratories for the countries in their specific region. For example, the laboratory in Khartoum, Sudan—already set up for onchocerciasis studies by the Carter Center—would support its home country and the other Arabic-speaking endemic country in the region, Yemen. The Carter Center has also established other specialized laboratories for onchocerciasis in Latin America (Ecuador and Guatemala) and in Africa (Ethiopia, Nigeria and Uganda), all of which have been key components in the success of the onchocerciasis and LF programmes in these countries.7,8 Figure 3. View largeDownload slide Potential distribution of regions that could be covered by a single reference laboratory. Based on current information, laboratories located in each area (coloured) could potentially serve the needs for that region. Figure 3. View largeDownload slide Potential distribution of regions that could be covered by a single reference laboratory. Based on current information, laboratories located in each area (coloured) could potentially serve the needs for that region. To ascertain the suitability of those laboratories selected in this first phase of expanding laboratory support, it is important to carry out an assessment of potential laboratories in these proposed regions. The criteria that could be used in this assessment are shown in Figure 4. The assessment of the selected laboratories using these criteria will most probably reveal a range of different capabilities in the various sites as well as variations in the needs and the strengths of each of these laboratories. This is important information that will assist in the creation of a strong QA system and support laboratory network across Africa, an essential component in assisting country programmes to attain successful elimination of onchocerciasis and other NTDs. Figure 4. View largeDownload slide Criteria used to assess the suitability of a laboratory as a member of the NTD support network. Figure 4. View largeDownload slide Criteria used to assess the suitability of a laboratory as a member of the NTD support network. The challenges In creating such a network, it is prudent to be aware of the potential challenges that may be faced in developing a support system such as a laboratory network in a multicultural, polypolitical continent such as Africa, an often logistically challenging region. There is, for example, the issue of country sovereignty of data; countries often feel protective about their own programme’s samples and the resulting data, and often insist on their national samples being processed in-country. It is also quite possible that being selected as a laboratory in the network has the potential of bringing new funds and expertise. An open mind is needed when deciding which laboratories should be included and, although the overall needs of the onchocerciasis and other NTD programmes must be a primary factor in selection, each case needs to be considered carefully and supported where possible. Developing such a network will also not be without significant cost, and this must be addressed as part of the overall planning; however, the fact that the laboratory component of a disease elimination effort is mandatory for success makes it likely that support will be made available. There are also logistic aspects of the network that need careful attention, including the storage and processing of data produced by the laboratories in the network. The WHO Regional Office for Africa and ESPEN are important parties in the discussion here and need to be major players together with the countries who own the data. Management of the provision of laboratory supplies, maintenance of the QA system and interlaboratory communication, including linking to the central agencies involved in the onchocerciasis elimination programme, are all major issues that need careful consideration and discussion. Efficient communication, both in the establishment phase and in the maintenance phase of such a network (e.g., responding to technical issues and reagent supply), is a major key to success, but this will need careful and constant attention. Comment It goes without saying that the essential indicator of the successful elimination of onchocerciasis will be based on information produced by laboratory testing. Likewise, it is very clear that developing the necessary facilities to provide these data in a high-quality manner is a priority for the global onchocerciasis elimination programme. It is likely that as countries further develop their national programmes, and reorient them towards elimination rather than disease control, there will be additional needs for new epidemiological mapping—largely due to the still unconfirmed onchocerciasis hypo-endemic areas in each country. Although this latter activity would be best achieved using the still needed OV16 antibody RDT assay (or at least an RDT of some type), there will still be a need for confirmatory laboratory-based testing to ensure the validity of any field-based RDT and results. As the transmission foci within countries approach the point of reaching local elimination, or at least the cessation of mass drug administration (MDA), there will be an increasing need for laboratory-based assessment of infected flies—an assay currently required by the WHO guidelines. In parallel with programmatic monitoring and evaluation, investigators continue to improve the tests used for mapping and elimination of this and other NTDs. These activities, essential components of any solid public health initiative, also require considerable field laboratory support. It is fully expected that the expanded laboratory network proposed and described here will also process the many research-oriented samples that will be generated. Conclusion It is extremely important that we further develop the capacity of endemic region laboratories to process, in an efficient and quality-assured matter, the increasing number of samples that are being generated as onchocerciasis programmes turn from MDA directed at disease control to programmes that are aimed at breaking transmission and finally eliminating this infection. We have described here an approach to increasing the capacity of the laboratories that presently exist in Africa and have identified many of the characteristics required for this enhanced laboratory network. Disclaimer: This publication does not state or reflect the views or opinions of the US government or US Agency for International Development. Author's contributions: The primary manuscript was written by CDM and JS; CD and TRU reviewed the manuscript and provided important content additions. Acknowledgements: None. Funding: None. Competing interests: None declared. Ethical approval: Not required. References 1 Diawara L, Traore MO, Badji A, et al. . Feasibility of onchocerciasis elimination with ivermectin treatment in endemic foci in Africa: first evidence from studies in Mali and Senegal. PLoS Negl Trop Dis 2009; 3( 7): e497. Google Scholar CrossRef Search ADS PubMed 2 Mackenzie CD, Homeida MM, Hopkins AD, et al. . Elimination of onchocerciasis from Africa: possible? Trends Parasitol 2012; 28(1): 16– 22. Google Scholar CrossRef Search ADS 3 Zarroug IM, Hashim K, ElMubark WA, et al. . The first successful confirmed elimination of an onchocerciasis focus in Africa: Abu Hamed, Sudan. Am J Trop Med Hyg 2016; 95(5): 1037– 40. Google Scholar CrossRef Search ADS 4 Guidelines for stopping mass drug administration and verifying elimination of human onchocerciasis: criteria and procedures. WHO/HTM/NTD/PCT/2016.1. Geneva: World Health Organization; 2016. 5 Mackenzie CD, Ashley Behan-Braman A, Hauptman J, et al. . Assessing the viability and degeneration of the medically important filarial nematodes. In: Shah MM and Mahamood M, eds. Nematology – concepts, diagnosis and control . London: Intech Open Access Publications; 2017, pp. 101– 20. 6 International Federation of Clinical Chemistry and Laboratory Medicine. Quality of management and quality of analysis: a handbook for developing countries jointly developed by C-CLM and C-AQ of the EMD. Rev. 2012-04-04. http://www.ifcc.org/media/210316/2012%20-%20C-CLM%20Monograph.pdf. 7 Richards FO, Eigege A, Miri ES, et al. . Epidemiological and entomological evaluations after six years or more of mass drug administration for lymphatic filariasis elimination in Nigeria. PLoS Negl Trop Dis 2011; 5( 10): e1346. Google Scholar CrossRef Search ADS PubMed 8 Meribo K, Kebede B, Feleke SM, et al. . Review of Ethiopian onchocerciasis elimination programme. Ethiop Med J 2017; 55( Suppl 1): 55– 63. Google Scholar PubMed © The Author(s) 2018. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: firstname.lastname@example.org.
International Health – Oxford University Press
Published: Mar 1, 2018
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