Lutte contre la maladie du sommeil et soins de santé primaire [Sleeping sickness control and primary health care]
This is the title of a 243-page book published by IRD in 2003, written by C. Laveissière, A. Garcia and B. Sané. It describes an IRD project to combat the resurgence of HAT in the Sinfra focus in west-central Côte d'Ivoire, using a village-based multidisciplinary approach that was efficient, low cost and acceptable to rural communities. This approach has potential for use elsewhere, particularly in inaccessible endemic areas.
The control programme (1995-1997) was intended to be both curative and preventive, and was based on medical surveillance and vector control. Key features of the programme were health education, training villagers as community health workers to undertake most of the essential tasks themselves, determining HAT seroprevalence, confirming and treating suspected cases, and establishing and maintaining an effective system of vector control.
The Sinfra focus
The number of recorded cases of HAT in the Sinfra prefecture rose from just six in 1990 to 208 in 1992; the actual number of cases was probably much higher due to the lack of diagnostic facilities, the fact that many villages are inaccessible by road, and a high level of population movement. Sinfra is situated in degraded forest, characterised by active deforestation and cash-crop agriculture, primarily cocoa. The human population is extremely heterogeneous, with the indigenous Gouro now forming an ethnic minority.
The vector in the Sinfra region is Glossina palpalis palpalis and the parasite is
Trypanosoma brucei gambiense. The epidemiological risk as an expression of the frequency of contact between man and vector, was highest in marshy areas on the edge of settlements where tracks crossed water courses, followed by water sources generally. Domestic animals, especially pigs, served as reservoir hosts.
The control project
In 1994 a team visited each of the 48 communities in the Sinfra focus to explain the project to the villagers and to answer any questions arising. Each community was asked to nominate two candidates to be trained as unpaid health workers, and two fullyequipped diagnostic laboratories were established in the area.
For each village, the community health workers prepared a population census, collected blood samples and determined HAT seroprevalence using the CATT technique. Suspected cases were examined by lymph node palpation and aspiration, and confirmed cases were referred to a regional health centre for free treatment following established protocols. Vector control was initiated in 1995 by the installation of 250 Vavoua traps and 15 000 black-blue-black screens at the end of the rainy season, 2-3 weeks before the human population was surveyed. The traps and screens were reimpregnated with deltamethrin at 25 g a.i./litre (90 mg a.i./screen) every six and four months, respectively. Entomological evaluations were carried out at monthly intervals.
Overall, 66 percent of the population was screened, although the level of coverage was not uniform. Disease prevalence was generally low, and highest (>3 percent) in the central zone around Sinfra itself. Seroprevalence (1.64 percent) was highest in the Gouro indigenous ethnic group and lowest in the Mossi (0.94 percent). Parasitological prevalence was consistently lower than seroprevalence (0.5-2.0 and 0 percent in villages where seroprevalence was 3.4-4.0 and 0.25-1.5 percent, respectively), which called into question the sensitivity of the diagnostic tests used.
After the installation of traps and screens, the apparent density of Glossina was reduced by 67 percent after one month and by >85 percent after six months. A reassessment of the epidemiological situation in 1997, two years after the initiation of control, showed that whereas HAT prevalence remained relatively high (>2 percent) in the centre of the Sinfra focus, in peripheral areas it had been reduced to <0.5 percent. Control failure in some villages was attributed mainly to large-scale population movements.
Conclusion
The success of the Sinfra project demonstrated clearly that an integrated control programme involving the recruitment and training of voluntary community health workers is an economic and viable option for HAT control. A detailed analysis of the results showed that this approach was more efficient and less expensive than the use of mobile units. The book includes a cost analysis, a discussion of the major problems encountered, and a series of appendices which include details of the control schedule, equipment, training, and methodologies used. Aimed at medical practitioners, decision makers and aid workers, this book contains sufficient data to assist similar programmes to be established elsewhere.
Report of a meeting organized by the DFID Animal Health Programme
A meeting entitled Tsetse control: the next 100 years, organized by the DFID Animal Health Programme was held in Edinburgh, UK, 9-10 September 2002. The report of this meeting has now been published by the DFID Animal Heath Programme. There follows here a summary of the Preface by Professor Ian Maudlin, a summary of the Introductory Essay by Simon Chater, and part of The Way Forward, by Steve Jones, the facilitator at the Edinburgh meeting. Elsewhere in this issue of Tsetse and Trypanosomiasis Information Quarterly can be found abstracts of some discussion papers contributed to the meeting.
The Preface of the report was written by Professor Ian Maudlin, early in 2003. The concept of the meeting was to allow the pro- and anti-eradication arguments relating to tsetse to be aired along with viewpoints arising from the control of American trypanosomiasis. Concerning the usefulness of the meeting John Kabayo of PATTEC is quoted as remarking that "it was a good idea and came at the right time...Everyone who wants to be involved is welcome...This is an international effort, to be built on what is already going on. There is room for everybody". Two weeks after the Edinburgh event there was a meeting of the advisory group of the PAAT; a statement arising from that meeting stated that "the... tsetse and trypanosomiasis community is united in its resolve to reduce and ultimately eliminate the constraint of tsetse-transmitted trypanosomiasis in man and animals." The Preface concludes expressing the hope that the tsetse and trypanosomiasis community can now present the unified front the donors want to see before they will once again invest in tsetse and trypanosomiasis control.
Tsetse elimination: sifting the arguments
This contribution "Tsetse elimination: sifting the arguments" is in the form of an essay written by Simon Chater based in part on the presentations made at the Edinburgh meeting. It was written at the invitation of DFID-AHP.
African trypanosomiasis is recognized by all as being one of Africa's most persistent and deadly scourges. African countries cannot by themselves marshal all the resources required to eliminate the fly; they will need the help of the developed world, but the donor agencies that could provide that help are unlikely to do so for as long as they receive conflicting messages on what is the best way forward. Of those who oppose tsetse eradication, two camps may be discerned. The first fears that the complete clearance of tsetse will lead to a threat to the survival of Africa's forest and savanna ecosystems. These non-interventionists may set great store by conservation but sometimes give the impression of ignoring the need to eradicate poverty and improve human health. The second believes that human population pressure, as it builds up, will inevitably bring about fly suppression by altering the ecosystem and putting in place all the infrastructure of human settlements. Large areas of northern Nigeria now support sizeable populations of animals and people free of tsetse-transmitted diseases, despite these areas being infested a century ago. However, these areas are virtually treeless and so less friendly as a home for tsetse than areas retaining some tree or bush cover; moreover most of these areas were originally cleared of tsetse by large scale spraying. This camp can be accused of complacency, especially as sleeping sickness is again on the rise. Both camps have in some degree overstated their case.
Early attempts at tsetse control were based on game hunting. There are difficulties in this method: it is destructive, it may not work if there are domestic livestock for the flies to feed upon, and it may be a problem to know which wild animals to destroy. Emphasis switched to bush clearing to destroy the habitat of the fly. Such clearing has to be repeated at intervals to suppress re-growth; biodiversity suffers, and the burning associated with the method releases carbon to the atmosphere. Ground spraying with DDT followed, but eventually raised environmental concerns due to the insecticide's accumulation in the food chain and its damaging effects on fertility. Switching to the synthetic pyrethroids proved somewhat more acceptable, but brought concerns for aquatic life-forms. Spraying has been shown to be successful if it is part of a well planned and well implemented control strategy, but the threat of re-invasion is ever-present. Traps of various designs can reduce the fly population of an area. Targets can be successful where funding and material resources are assured, and periodical re-servicing practicable. Disease control by drugs has been important and remains the farmer's main defence against the disease. However, increasing disease resistance and lack of alternative drugs are leading to serious problems. Trypanotolerant cattle breeds are locally successful in some tsetse-infested West African situations, but do not have the productivity and traction power of the larger zebu breeds. Pour-on insecticides applied to the cattle directly can help to protect them, and costs in this area may be falling. All the above methods of tsetse control rely on regular servicing and protection of reclaimed areas from reinfestation, a protection which is often ineffective.
To overcome the expensive and disappointing cycle of control and re-infestation, it has been proposed that total eradication of tsetse species from Africa should be undertaken. A successful campaign using SIT against the screw worm fly in Central and South America provided a model of what might be done. After inconclusive trials against tsetse in parts of Nigeria, Tanzania and Burkina Faso, SIT was employed in Zanzibar, followed by confirmation that the tsetse there had been eliminated. PATTEC was formed by those in favour of strongly backing SIT for the eradication of tsetse. Their case was taken to OAU, which in July 2000 gave its political support to the proposal to eradicate tsetse from the entire African continent, within a time frame of 100 years. Priority areas of tsetse infestation would be areas of high population density and/or high agricultural potential. Areas close to those already cleared would also get attention, to consolidate gains and lessen the threats from re-invasion. The main attack would be against Glossina morsitans and G. pallidipes. From the economic angle, eradication (if it should be possible) would avoid the need for repeated treatment that is required for control of the fly. However, the SIT technique is not a simple one. Rearing stocks of tsetse is an expensive and difficult technique, and each species has to be treated separately. Finding isolated belts of tsetse is difficult, and once these are dealt with, SIT will face the perennial problem of re-invasion of cleared areas, until the eradication goal is achieved. The area of Africa from which tsetse would have to be eliminated is about 8 to 10 million km2, covering some 36 countries, not all of which are politically stable. Access can be extremely difficult, and local veterinary services may be too weak for the task. Some economists have argued that other more pressing priorities exist in Africa, especially the fight against other human diseases; the price tag of US$20 billion for the eradication of tsetse is too great, even when spread over the long time scale envisaged.
It is to be hoped that the proponents of tsetse control on the one hand, and tsetse eradication on the other, will find common ground, by recognising that they are both tackling the same basic problem. Moreover, early stages in an eradication campaign will take the form of area by area, species by species, reduction of the tsetse population. Both camps will gain from a better definition of what SIT can and cannot do. The writer of the essay concludes that instead of devoting large sums of money to SIT, it would be better to spend smaller amounts on strengthening conventional control. In particular, livestock producers should be helped to develop and refine their on-farm control practices, and traps and barriers should be made more effective. PATTEC should not push a single control technique, but continue to serve as a platform for identifying priorities, raising funds, organising projects and co-ordinating them across national frontiers.
The way forward
Under this title, the facilitator of the Edinburgh meeting, Steve Jones, set out a series of "Points of broad agreement", "Areas for further discussion", and proposed "Next steps". Only the "Next steps" are dealt with here (with minor editing changes): the reader is directed to the Report itself for the other two items.
Although it is recognized that PATTEC is an African initiative, there is a need to link technical expertise in Africa with that beyond the continent to enable the entire international tsetse and trypanosomiasis community to provide expertise and advice. PAAT is well placed to support PATTEC, e.g. by co-ordinating research and providing advocacy for resource mobilization. Institutional competition and territoriality have created difficulties in defining a way forward: we need a change of attitude if we are to serve PATTEC better. If African countries want donor support for tsetse and trypanosomiasis control, these activities need to be included in Poverty Reduction Strategy Papers (PRSPs) (government responses to UN poverty reduction targets) and be on the agenda of the New Economic Partnership for African Development (NEPAD). Decision support tools need to be developed to facilitate objective selection of the most appropriate technologies and approaches in any given situation. PATTEC needs to formulate sound project documents to attract donor support. A holistic approach is needed in which tsetse and trypanosomiasis fit into the bigger picture. The PATTEC Plan of Action should be made widely available. At present, relatively few people have had the opportunity to see this document. PATTEC should consider ways of incorporating a wider diversity of opinions into any revised Plan of Action. PATTEC needs to formulate a clear reply to the points made by the UK Secretary of State for Development. PATTEC needs to devise an effective communications strategy, perhaps following the example set by the Roll Back Malaria Campaign.
A circular from Raffaele Mattioli, PAAT Secretariat Focal Point, Animal Health Officer (Integrated Health Management), Animal Health Service, Animal Production and Health Division, FAO, Viale delle Terme di Caracalla, 00100 Rome, Italy [Phone (+39) 0657056078; e-mail: [email protected]] states that the PAAT website can be visited at the following address: http://www.fao.org/ag/againfo/programmes/en/paat/home.html. It is planned to produce a French and Spanish version of the above website. Suggestions and comments would be welcome at the PAAT website.
The following news item has been received from Dr John Kabayo, PATTEC Coordination Office, AU, PO Box 200032 Addis Ababa, Ethiopia, on 18July 2003.
During the OAU Summit held in Lome, Togo in July 2000 the African Heads of State and Government adopted Decision AHG/Dec.156 (XXXVI), urging member states to embark on a Pan African Tsetse and Trypanosomosis Eradication Campaign (PATTEC), to free Africa from the effects and consequences of tsetse-transmitted diseases. Within the framework of this decision, the Commission of the African Union was assigned the task of mobilizing and coordinating the activities necessary for executing the objectives of the campaign. In the context of fulfilling the obligations of this assignment, the Commission of the African Union has been able to do the following:
Prepared a Plan of Action to guide the process of implementing the purposes of the PATTEC initiative;
Established a PATTEC Coordination Office to help mobilize the commitment, support and action necessary to sustain the operations of the campaign;
Sought and obtained the consensus of mandated international organizations (UN ECOSOC, IAEA, FAO and WHO) in support of the implementation of the PATTEC Plan of Action;
Inaugurated the PATTEC Policy and Mobilisation Committee, a body charged with the task of overseeing and guiding the activities of the campaign on behalf of the Member States of the African Union;
Held several regional and inter-state meetings of high level experts and senior government policy officials in charge of tsetse and trypanosomosis control to discuss joint plans and strategies and consider the modalities of cooperation in the eradication of tsetse and trypanosomosis in several groups of countries (including: ECOWAS countries; Ethiopia and Sudan; Angola, Botswana, Namibia, Zambia and Zimbabwe);
Held formal consultations with the Secretariats of Regional Economic Communities (RECs), including COMESA, SADC, East African Community and ECOWAS as well other partners in Africa, including the African Development Bank, NEPAD with which Memoranda of Understanding on cooperation with the African Union in the implementation of PATTEC were discussed and agreed;
Launched a bi-annual newsletter: the PATTEC Newsletter to provide information and act as a medium of exchange of ideas and opinions on the activities related to the implementation of the PATTEC initiative;
Developed several training manuals and publicity and public information materials with themes on PATTEC for publication;
Managed a Training Course on the application of GIS in tsetse and trypanosomosis control interventions for 21 participants from 13 countries in East and Southern Africa (with assistance from the International Atomic Energy Agency);
Assisted several countries to develop national plans and strategies on the implementation of the PATTEC initiative in the affected countries;
Incorporated the PATTEC Coordination Office in the structure of the Commission of the African Union to help coordinate the campaign, with a mandate to remind Member States about their individual and collective obligations to the implementation of the PATTEC initiative, and generally to drum up action, mobilize commitment and support to ensure sustained action.
