REPORTS AND RECOMMENDATIONS
RAPPORTS ET RECOMMANDATIONS
1. ISCTRC celebrated its 50th
Anniversary at its previous conference in 1999 in Mombasa, Kenya. At this memorable occasion, the ISCTRC
awarded gold and silver medals to distinguished scientists for their
outstanding contributions to the cause of tsetse and African Trypanosomosis.
Following
the recommendations of the 25th ISCTRC conference and in recognition
of the hardships tsetse and Trypanosomosis imposes on the livelihood of rural
communities in sub-Saharan Africa, the OAU Heads of State and government during
their summit in Lome, Togo in July 2000 and, subsequently, in Lusaka, Zambia in
July 2001 declared a campaign for the eradication of tsetse flies from the
continent of Africa. The Secretary
General of the OAU was instructed to supervise the tsetse eradication campaign
and also called upon national governments to include tsetse eradication in
their respective national development plans.
A
Task-force of 22 people appointed by the OAU Secretary General met in Nairobi,
Kenya in December 2000 and developed a conceptual framework and a short-term
action plan of the Pan African Tsetse and Trypanosomosis Eradication Campaign
(PATTEC). This was endorsed at the
Lusaka OAU Summit in July 2001 and a co-ordinator has since been appointed and
temporarily posted at the OAU Headquarters, Addis Ababa, Ethiopia.
OAU/IBAR
conducted two days (29-30 September 2001) Orientation workshop for Directors of
Animal Resources and Veterinary Services on Policy Planning and Strategy on
PATTEC Implementation in Ouagadougou, Burkina Faso.
OAU/IBAR
and ISCTRC Secretariat continue to co-operate and collaborate with
international and Regional Institutions and organizations such as FAO, WHO,
IAEA, ILRI, ICIPE, PAAT, OIE. It was
announced that PATTEC would be officially launched on Friday afternoon, 5
October 2001.
With
regards to projects co-ordination and implementation, it was reported that
Farming in Tsetse Infested Areas (FITCA) was operational in Ethiopia, Kenya and
Uganda. The West and Central Africa
project proposal is with the EU awaiting for their decision.
Pipeline
projects under PATTEC Framework include the Ethiopian SIT Project, Lake
Victoria Basin countries of Kenya, Uganda, Tanzania and the ongoing projects in
Botswana, Burkina Faso and Mali.
2.
PATTEC – Pan
African Tsetse and Trypanosomosis Eradication Campaign was born on the premise
that there is consensus on the negative effects of tsetse and Trypanosomosis on
the development and welfare of rural populations in sub-Saharan Africa, and on
the need to rid the affected areas of this menace. Tsetse eradication is technically feasible. It is politically and
economically desirable. To achieve
this, Africa should be as resolute as she was in her fight for political
liberation. Now that a momentous
political decision has been made, it is up to the scientists to bear the
responsibility to translate this political decision into practical
reality. Scientists should identify
zones that are isolated or isolable to be tackled such as the Botswana,
Ethiopia, Mali/Burkina Faso SIT Projects.
African countries
should act and chart out mechanisms for support and coherence, despite some
dissent in some quarters. Achieving the
PATTEC objectives will require great determination and support from the
international community.
3.
PAAT - The Programme
Against African Trypanosomosis was formed five years ago under the three
mandated UN Agencies, WHO, FAO and IAEA together with OAU/IBAR to create an
international forum in tsetse and Trypanosomosis control. It has the goal of improved human health,
food security, sustainable agriculture and rural development.
The
principal functions of PAAT are to provide expert advice, establish international guidelines for tsetse and
Trypanosomosis interventions and related development activities, develop decision
support systems for the selection of priority areas and most appropriate
strategies for interventions, increase international awareness of the problem
of African Trypanosomosis in man and
animals and, assist in the mobilization of
international support for tsetse and Trypanosomosis interventions.
An
important activity over the past year has been to develop the process of
harmonization between PAAT and PATTEC. This process is being developed through
a series of meetings between the secretariats of PAAT and PATTEC. One of the
chief functions of PAAT is to be an important supportive forum for PATTEC and
provide international expertise on various aspects of tsetse and Trypanosomosis
management and the associated issues of land use, environmental protection and
long-term sustainable agricultural development.
4.
FAO - The work of the Food
and Agriculture Organization (FAO)
incorporates, inter alia, normative and production of guidelines to
promote sustainable livestock and overall agriculture production. In tsetse and
Trypanosomosis, three principles are followed; the integration and optimisation
of technical tools: the integration of tsetse and Trypanosomosis programmes
into overall agricultural development: and the social, economic and environmental
long-term profitability of interventions.
FAO held a
meeting for liaison officers on tsetse and Trypanosomosis in East and southern
Africa in September 2000 in Addis Ababa, and for central and West Africa in
September 2001 in Ouagadougou. Workshops on Strategic Planning of Area-wide
Tsetse and Trypanosomosis control in West Africa were held in November 2000 in
Geneva, Switzerland and in May 2001 in Ouagadougou, Burkina Faso. FAO plans to
hold similar workshops one each in East Africa, and Central/Southern Africa in
the year 2002. FAO co-ordinates a number of PAAT activities. A PAAT secretariat
meeting was held in February 2001 IAEA, Vienna, Austria at which PAAT-PATTEC
harmonization was discussed. A document on “PAAT-PATTEC most frequently asked
questions” was produced.
PAAT-Information
System (PAAT-IS) housed at FAO headquarters, Rome, Italy is composed of GIS,
Bibliography, and Resource Inventory, the website
(www.fao;org/paat/html/home.htm), the PAAT Newsletter. The Information System
is available on CD from FAO, Rome or can be downloaded from the web
(ergodd.zoo.ox; ac.uk/paatdown/index.htm).
The TTIQ
new editor is Dr. John Pollock and can be reached on e-mail johnnpollock@hotmail.com. ESRI Arc
View and Spatial Analyst has donated copies of Arc View 3.2 and Spatial Analyst
2.0 software necessary to operate Geographical Information System (GIS)
component of PAAT-IS.
FAO is
supporting a TCP project on Sustainable Control of Tsetse and Trypanosomosis in
the Sudan. It was approved in December 2000 and become operational in 2001. The
first part of a study on quality control of diminazene preparations in
sub-Saharan Africa by the University of Strathclyde was concluded and the
results presented at the 7th PAG meeting.
5. IAEA - The International Atomic Energy
Agency congratulated OAU/IBAR and Member States on their efforts to generate
awareness and commitment at the very top political level in Africa to try solve
the tsetse and trypanosomosis problem.
The political decision gave birth to the Pan African Tsetse and
Trypanosomosis Eradication Campaign (PATTEC) and Plan of Action.
The
specific IAEA contributions to tsetse and trypanosomosis control efforts
include normative work and applied research under the FAO/IAEA Programme and
IAEA’s department of Technical Co-operation. The Agency is active in the field
of improved diagnosis of the disease and the SIT component. FAO/IAEA focus on
developing, standardising and validating diagnostic methods and surveillance. IAEA
closely collaborated with other PAAT Secretariat members and is standing firm
behind OAU and PATTEC as they are convinced that any meaningful campaign at
sustainable elimination of the trypanosomosis problem has to be owned and led
by the problem holders i.e. the Africans.
The budget
of IAEA TC’s Department in the next 10 years is projected at about US$30
million. The funds will be allocated
for support to PATTEC efforts, to upgrade existing and establishment of rearing
facilities, assist national and sub-regional efforts in priority intervention
zones, and to encourage other partners to support post-tsetse eradication
development of livestock-agricultural systems.
6. ICIPE – The International Institute of Insect Physiology and Ecology congratulated the OAU Heads of State and Governments for their historic declaration and attention to this most serious problem in livestock and crop-based agriculture, namely tsetse and trypanosomosis.
Human
trypanosomosis is again rearing its ugly head, taking on increasing toll on the
African workforce with 500,000 cases per year, the disease is back to its
levels of the 1930s. Trypanosomosis is
indeed a development issue. Having
researched on tsetse and its management for over 30 years, ICIPE understands
the enormity and difficulty of the problem.
ICIPE
pointed out some of the difficulties likely to be encountered with an
“eradication approach.” Some of these are that tsetse are very unique insects
well adapted to their habitat and there are 22 different species, each with
unique behavioural and habitat preferences.
This suggests that there are actually 22 problems and that there will be
no easy solutions because of this complexity.
Consider the Sterile Insect Technique (SIT) proposed as a “final”
solution. It will require 22 different
species of sterile males in enormous numbers to have the eradication
effect. Tsetse too have a remarkable
ability to re-invade cleared areas.
Therefore, African countries must join together to manage this menace,
which knows no international borders.
ICIPE, however, have serious concerns on the biological and logistical
feasibility and the economics of the tactic being considered.
Reaching
the critical mass of man-reared tsetse will be much more difficult as tsetse
have low reproductive rate (Glossina
pallidipes has about 10 progeny).
ICIPE estimate, based on Zanzibar SIT project estimates, that to cover
10-20,000 km² will require 500,000 sterile males a week, or 24 million in a
year. To achieve these figures, about 2
million producing females a week will be required. In addition, 19 tons of hygienic blood will be needed yearly to
maintain such a colony.
The cost of
eradicating tsetse with SIT in Zanzibar (an isolated island off Tanzania
mainland) was US$5.8 million. To clear
the whole continent, DFID estimates US$20 billion will be needed.
ICIPE suggest that an integrated approach is the most sustainable. An approach that local communities can manage, affordable
within the limited budgets of African countries and communities and deals with
all the complexities of tsetse behaviour and biodiversity. ICIPE will render support in any way to
helping Africa solve this very complex and all-encompassing development issue.
7.
ILRI – trypanosomosis
research activities at ILRI are conducted within the broader livestock research
and development context. ILRI has six
disciplinary research programmes including: health; genetics; feed and
nutrition; policy; systems analysis and impact assessment, and people,
livestock and environment. ILRI
research activities are closely linked to research activities with regional and
national parties or partnerships with advanced research institutes in developed
and developing countries.
The purpose of
ILRI’s trypanosomosis research is to reduce poverty, improve food security and
conserve the environment, through sustainable improvements to controlling the
disease. There are three broad themes: understanding the impact of
trypanosomosis within priority farming system and ecological contexts; development
of improved diagnostic methods, and research findings which contribute to the
basic and applied scientific basis for improving trypanosomosis control in
animals and humans.
Research is
being conducted in trypanotolerance, vaccine development, diagnostics and
molecular biology, epidemiology, socio-economics, environmental monitoring and
the development of decision support tools.
Trypanotolerance
has been a major research focus for more than two decades. Vaccine development was reviewed recently. Following the review, a series of trials to
assess the infection-blocking vaccines targeting the flagella pocket were
conducted. The trials did not
demonstrate efficacy and development of the anti-infection vaccines was
discontinued early in 2001. Work
continues on the anti-disease, Congo pain, vaccine as a joint project, between
CIRAD-EMVT, IRD and ILRI.
Epidemiological
research focuses on assessment of alternative control options, drug resistance,
and cattle-human transmission of Rhodesiense sleeping sickness new
socio-economic research projects have begun to assess delivery systems,
estimate transaction costs and assess the economic issues associated with
tsetse and trypanosomosis control. ILRI
is also placing increasing importance on environmental monitoring and impact
assessment of order ecological impacts of changes in agricultural activity
including disease control programmes.
8. ITC – Research work at the
International Trypanotolerant Centre is organised according to low-input
systems, market oriented (intensive) systems, and those that cut across the two
systems. All institutional projects are under the three programmes; low-input
systems improvement programme (LISIP), Market-Oriented Systems Improvement
Programme (MOSIP) and Systems Overlaps and Linkages Improvement Programme
(SOLIP).
The mission
of ITC is to contribute to the efforts of increasing livestock productivity and
utilisation in the West Africa region through the optimal and sustainable
exploitation of genetic resistant of indigenous breeds of livestock for the
welfare of the human populations. The
Centre closely collaborates with the various NARS in the region and has
contributed towards strengthening their capacities. Also ITC closely collaborates with CIRDES and ILRI, with whom
they have some joint projects.
Through
scientific publications, ITC has demonstrated to the international research and
development communities the worthiness of trypanotolerant livestock of West
Africa.
9. OIE
(NTTAT) - The
Non-Tsetse Transmitted Animal Trypanosomosis group, which originally sought to
control Trypanosoma evansi, has had
its activities extended to other trypanosome infections not transmitted by
tsetse flies. Research workers are encouraged
to carry out research in their respective countries. Aspects being looked at now include diagnostics and
chemotherapy. The main research
findings vary greatly and concern epidemiology, diagnostic methods and basic
molecular biology techniques.
10.
CIRDES – was
born from the CRTA (Animal Trypanosomosis Research Centre) in 1992, as a result
of a decision by Heads of State of the five "Conseil de l'entente "
Member States: (Benin, Burkina, Cote d'Ivoire, Niger, Togo. Its activities also extend to Mali and
Ghana.
The centre
is organised into three (3) units of research: URBIO, UREEN, URPAN. CIRDES activities are largely dominated by
research and the fight against trypanosomosis and its vectors.
The
activities related to trypanosomosis are, disease diagnosis, chemoresistance,
trypanotolerance, tsetse control, and the socio-economic impact of tsetse and
trypanosomosis control.
During the
last two years, CIRDES has been restructured and its scientific activities primarly
concern the implementation of the joint programme for Research/Development on
Livestock (PROCORDEL).
The
research projects submitted by the NARS have been selected and are financed by
PROCORDEL. Each project is based in the
NARS under the responsibility of a national research worker. Training programmes are provided for the
duration of the project, on diagnosis and the identification of
epidemiologically important areas.
11. WHO – The Word Health Organisation
(WHO) reported considerable progress in the development of public-private
sector partnerships that had resulted in securing supplies of essential drugs
to treat sleeping sickness, for surveillance activities, and for development of
new and improved drugs. WHO and the pharmaceutical company Aventis have an
agreement under which $25 million was provided for drugs, surveillance,
development of oral formulation, and other research and development activities.
Countries
requiring these drugs can request them from WHO and will only pay shipping costs.
Although not directly involving WHO, a grant of $15.1 million has been obtained
from the Gates Foundation for the development of new drugs for the treatment of
HAT.
Despite the above positive progress, the need for advocacy for HAT for additional funds still continues as the Aventis Agreement in only for 5 years.
Moderator : F. Y. Boa
Rapporteur : M. Odiit
Ten papers
were presented during this session. Seven of these were describing general
epidemiological aspects of the disease in different foci. Two were on drug
development. One paper concerned the wild animal reservoir.
In the
papers on the general epidemiological aspects, it was observed that when
compared to 1989, the number of cases in the ancient focus of North Benin
increased from 1 to 7. In the focus of Haut Mbomou, it is estimated that the
annual cost per person protected was US $ 4.1. Despite the efforts of the
national programme, and other field interventions, the case detection
activities covered only 14% of the population in the focus of Haut Mbomou. The focus is at the border. It is therefore
necessary to have trans-border coordination and collaboration.
A paper
from Nigeria reported that the Abroka focus of sleeping sickness is not shown
on the WHO map of the 250 foci. The map should be updated. The Abroka focus is
an important tourist area. The disease is mainly restricted to the riverine
system.
One of the
papers on epidemiological aspects reported the experience of a control
programme in Equatorial Guinea. There may be some indication to treat
sero-positive but parasite negative individuals. However, the augmentation of
the sensitivity of parasitological methods and the specificity of serological
tests is first necessary. In the Luba focus, it may no longer be cost-effective
to continue surveillance but to maintain the staff it is suggested that the
monovalent mobile screening teams should be made polyvalent and sentinel sites
for surveillance of sleeping sickness should be introduced.
A paper
from Burkina Faso reported that six patients diagnosed and treated in
Bobo-Dioulasso hospital, came from Cote d’Ivoire. Epidemiological surveillance
should be reinforced and a geographical information system between Cote
d’Ivoire and Burkina Faso be established to tackle the problem at its
geographical origin.
The paper
on the geographical distribution of detected cases in Cote d’Ivoire during the
last 6 years reports that most cased came from the sub-prefectures of Bonon,
Sinfra and Oume situated in the West-Central region. Appropriate measures should be undertaken to contain this endemic
situation.
The last of
the paper on epidemiological aspects of sleeping sickness addressed the
development of a mathematical model for estimating the level of under reporting
cases. Using the model, it is estimated that in Tororo and Busia districts in
Uganda, there are two unreported sleeping sickness cases for every three
reported and that for every reported death, there are 15 unreported.
Of the papers
on drug development, one reported the progress of the trials of DB289 a
diamidine, in vervet monkeys. Several
doses have been tried ranging from 1-10 mg/kg body weight. So far no relapses have been detected in the
monkeys treated at 10 mg/kg for 5 days. This study is on-going. The other paper
on drug development presented preliminary results of the assessment of a
concise schedule for melarsoprol and indicated that it is as safe and
efficacious as the long schedule. Compliance appears to be better. Some
national governments are already increasing the number of centers that are
adapting the new schedule. Final results of IMPAMEL II are awaited.
The paper
on the wild animal reservoirs reported that 8 percent of 724 wild animals whose
blood was examined by PCR using primers for T.
b. gambiense were found positive suggesting that wild animals may be
reservoirs of sleeping sickness. Further investigations on the role of animals
as reservoirs of sleeping sickness was recommended.
1.
Trans-border
coordination and collaboration should be encouraged to tackle the problem with
sleeping sickness cases that migrate.
2.
Sleeping
sickness mobile teams should be transformed from monovalent to polyvalent.
3.
Suggested
mathematical models for estimation of the true magnitude of the sleeping
sickness problem should be evaluated.
4.
The
WHO map of foci of sleeping sickness should be updated.
5.
The
role of animal reservoirs in the transmission of T. b. gambiense sleeping sickness should be investigated.
6.
Governments
of countries with sleeping sickness should accord more importance to the
disease and avail more financial, human and material resources. The integration
of sleeping sickness control in routine health services was recommended. Research on obstacles to the integration of
sleeping sickness control should be carried out.
Moderator : Grace
Murilla
Eleven
papers were presented during this session and over 10 posters exhibited. Of the 11 papers two dealt with
trypanotolerance, seven addressed various issues related to trypanocidal drugs
including pharmacokinetics and resistance, while two were concerned with
mechanically transmitted trypanosomosis.
In the area
of trypanocidal drugs, cases of resistance to isometamidium were reported from
Ethiopia and Burkina Faso. Two alternative approaches to assessment of
resistance were described; use of PCR and drug-ELISAs. Concern was voiced about
the administration of trypanocidal drugs by non-professionals and the consequent
need to provide information to farmers on the correct use of these products.
Data were presented that showed that the pharmacokinetics of isometamidium
differed between sheep and goats, which may have implications for the
prophylactic regimes that should be recommended for these species. High
variation in pharmacokinetic parameters, such as Cmax, observed
between individual cattle treated with diminazene aceturate may help explain
some cases of drug failures. A formulation of diminazene was reported to be
ineffective in the treatment of T. evansi
infections in camels.
The
epidemiology of mechanically transmitted T.
evansi infections in Mauritania was described. It was suggested that small ruminants
could act as a reservoir of infection. The epidemiology of T. vivax infections was compared in South America and Africa and it
was concluded that it was not possible to assess the importance of mechanical
transmission in Africa. Mechanical transmission of T. evansi infections by Tabanids on a dairy farm in Blue Nile State
of Sudan was described. The disease prevalence correlated with seasonal
abundance of biting flies, which were observed to be most active in the
afternoon.
In the area
of trypanotolerance, West African Dwarf goats were shown not to be superior to
WAD x Sahelian crosses. Neither deworming or plane of nutrition had any effect
on the course of anaemia following infection with T. congolense in either breed. Microsatellite markers were
identified that significantly correlated with breed and could differentiate
between zebu, Somba and Laguaire breeds of cattle.
1.
Pathogenicity
of T. evansi infections in livestock
species other than camels should be investigated.
2.
Significant
differences observed in pharmacokinetic parameters between sheep and goats
treated with isometamidium suggest it may be appropriate to recommend different
prophylactic regimes for the two species.
3.
Recognising
that there is an increasing tendency for trypanocidal drugs to be administered
by non-professionals, increased efforts should be made to promote good practice
amongst farmers and non-professionals, including camel owners.
4.
Internationally
agreed standards are required for the various trypanocidal drugs to facilitate
the enforcement of quality control in the market place.
5.
Interest
in trypanotolerance appears to be waning although at the same time there seems
to be increased opportunities to exploit ‘new science’ such as biotechnology
and genomics. It is therefore recommended that efforts be made to stimulate the
application of these techniques in relation to trypanotolerance.
PROTOZOOLOGY/IMMUNOLOGY AND DIAGNOSIS
Moderator : J.M. Ndung’u
Rapporteur : P.H.
Clausen
Felix Kuzoe (WHO/TDR) presented a report of the scientific working group (SWG) meeting of the UNDP/World Bank/WHO Special Programme on Research and Training in Tropical Diseases (TDR):
In 1998,
TDR underwent an external review. It
was decided that TDR would hold scientific working group meetings to address
each of the ten diseases the programme handles. The SWG meeting on African Human Trypanosomosis, held this year
in June 2001, was the first meeting.
During this meeting it was emphasized, that the recent re-emerging
outbreaks of sleeping sickness and increasing drug resistance have demonstrated
the potential danger in any endemic area.
In the 60s, sleeping sickness had been brought down to low endemic
levels practically everywhere in Africa.
Since then most of the national sleeping sickness control programmes
have been gradually sacrificed in favour of more prominent health needs. As a result, the core of national know-how
simply disappeared, rendering, as well, the dependency on external support even
greater.
Recent
outbreaks were an eye-opener worldwide to the seriousness of the situation.
The
objectives of the SWG were to:
-
Identify
areas where there are gaps in knowledge and studies that were necessary to fill
them.
-
Identify
research that is directly relevant to control programmes and treatment centres
as a priority
-
Promote
development of new tools for control.
-
Set
objectives for research capability strengthening for basic science, genomics
and applied genomics, drug discovery and development in disease endemic
countries.
The SWG
recommended networking and cross-country comparison of research progress to
assist in capacity building and stimulate cross border interest and advocacy.
The majority
of scientific papers presented during this morning session were dealing with
Human African Trypanosomosis (HAT). The
papers were covering two major themes:
1.
Epidemiology
of Trypanosoma brucei gambiense - HAT
and
2.
PCR-detection
of HAT and livestock trypanosomes.
The first
paper (201) reported on experimental T.
b. gambiense infections in pigs, which seem to eliminate T. b. gambiense spontaneously in less
then four months. It was concluded,
that the pig reservoir of sleeping sickness would be suppressed by vector
control measures over at least one year - provided that no wild animal
reservoir is allowed to re-introduce the parasite in the meantime. In the discussion that followed this
presentation, it was stressed, that more evidence is needed, whether pigs are
the most important reservoir hosts in T.
b. gambiense-HAT.
A series of
papers (202, 206, 207, 208, 209, 210 and 214) reported on the identification
and genetic characterization of HAT and livestock trypanosomes by molecular
diagnostic techniques, such as random amplified polymorphic DNA (RAPD),
amplification of microsatellite sequences, single PCR based on the ribosomal
internal transcribed spacer-1 (ITS-1) region and a PCR assay using a primer set
derived from the serum resistance associated (SRA) gene of T. b. rhodesiense. The developed
SRA-based PCR reaction (paper 209) was able to distinguish T. b. rhodesiense from all the other members of the Trypanozoon sub- genus.
It was
reported that amplification of livestock pathogenic trypanosomes by PCR using
primers amplifying a known DNA sequence of specific size has considerably
increased sensitivity and specificity.
However, the costs of the PCR are high, and, for example in cattle, the
multiplicity of pathogenic species can enable carrying out up to 5 reactions
per sample. Paper 208 and 210 reported
on the detection and identification of livestock trypanosomes through a single
PCR (Pan-Trypanosome PCR assay), based on ribosomal ITS-1 amplification.
A first set
of primers was evaluated and confirmed to be able to detect and distinguish all
pathogenic Trypanosoma species,
including 3 Trypanosoma congolense
types and T. theileri, however,
distinction among species of the Trypanozoon
subgenus was not possible. Further work
is envisaged to increase the test sensitivity and specificity, e.g. to avoid
interferences of commensal kinetoplastids in vectors. Within the Trypanozoon
subgenus, it was evident that the ITS-1 region is not useful as a molecular
marker to differentiate T. evansi,
the causative agent of surra from T.
equiperdum, the causative agent of dourine (paper 210).
The ELISA
for T. b. gambiense built on earlier
work on immune trypanolysis with VAT LiTat 1.3, 1.5 and 1.6. The inhibition
ELISA developed offered significant advantages over alternative test in terms
of both convenience, safety, specificity and sensitivity.
1.
Further
elucidation of the epidemiological significance of animal reservoirs in T. b. gambiense-HAT.
2.
Validation
of the test-sensitivity and specificity of the newly developed DNA-based diagnostic
techniques, using samples/isolates from well controlled field
studies/investigations.
3.
Development
and validation of serological and nucleic acid-based tools to monitor the
success of chemotherapy/prophylaxis in sleeping sickness and nagana.
MOLECULAR BIOLOGY/BIOCHEMISTRY
Moderator : Issa
Sidibe
Rapporteur : Dethie
Faye
Two papers
were presented during this session. These papers were focused on the use of
RP-HPLC/LC-MS for the determination of diminazene aceturate in pharmaceutical
formulation and for the study of the metabolism and distribution of
phenanthridine trypanocides in Trypanosoma
brucei respectively. The authors of
the study on the determination of diminazene aceturate in pharmaceutical
formulation started by reviewing the causes of drug resistance and among them,
drug underdosing due to poor drug quality (substandard drugs,
counterfeits). The authors raise the
fact that for some active ingredient like diminazene, there was no
pharmacopocial specifications since 1955.
The results of the analyses revealed that the quality of diminazene in
international commerce appears to be compromised and this may contribute to the
development of resistant clones of trypanosomes. It should be emphasise that 102 samples were analysed from 11
countries in Africa and one unmarked.
The HPLC method was found to be a simple and reproducible method for
routine use in the quality control of diminazene in bulk/formulation.
The second
study in this session aimed to investigate the metabolism of Isometamidium
chloride hydrochloride (ISM) and Ethidium bromide (EBr) in Trypanosome brucei by the HPLC and LC-MS analyses.
Trypanosoma brucei (although not susceptible to Isometamidium)
was used because the only trypanosome species available. The findings from this
work was that EBr is metabolised to a small extent (less than 1% in
trypanosomes, unlike ISM for which no metabolite could be detected. ISM has a greater affinity for the
kinetoplast than EBr and it stains other organelles such as the flagellum. In
this contest the distribution of EBr is more diffuse.
1.
Review/Prioritisation
of regulatory control and enforcement for veterinary trypanocides (drugs) in
Africa.
2.
Elaboration
of pharmacopoeal/international specifications for trypanocides.
3.
Extension
of this kind of studies to other trypanocides.
VECTOR (TSETSE) CONTROL
Moderator : V. Codjia
Rapporteur : W.
Shereni
A total of
six papers were presented on Vector (Tsetse) Control. The presentations covered
work on tsetse control field operations, community participation, estimation of
tsetse population densities, management of dairy cattle to reduce
trypanosomosis infections and the use of chemosterilants on targets.
Important
findings were produced from studies carried out in the Yale agro-pastoral zone
of Burkina Faso and in the Nguruman area of Kenya on the willingness of farmers
to participate in tsetse control projects. Predication models based on the use
of Contingent Valuation techniques were useful in estimating farmers’
willingness to pay for tsetse control in labour and/cash in Burkina Faso.
Studies in Kenya revealed that the adoption level of the NG2G trap by the
farmers in Nguruman was 35 %. The contribution by farmers was demonstrated in
both studies as an important requirement for the sustainability of tsetse
control programmes. Farmers’ attitudes for tsetse control are important in
determining the level of participation. There were indications from the studies
that community involvement is influenced by factors such as ownership of cattle
and revenue from milk sales, membership in formal (producer groups) and
informal rural organisations, knowledge of trypanosomosis and its vectors,
distance from project area, and involvement in other activities not related to
tsetse control. Farmer contributions are usually less than the total amount
required for a tsetse project. This suggests the need for subsidies from either
Government, donors or other sources. It would appear that farmers are more
willing to contribute labour only than to contribute both labour and money for
the purchase and maintenance of traps and targets.
Recent
tsetse control operations in Botswana demonstrated the importance of selecting
the most effective and appropriate tsetse control techniques depending on
prevailing circumstances and the need to integrate different strategies. The
integrated strategy in Botswana involved the use of curative and prophylactic
drugs, the use of aerial spraying and targets and the release of sterile males.
The reintroduction of aerial spraying in Botswana brought the technique into
the limelight and demonstrated the improvements in the navigational track
guidance and in monitoring the application of spray droplets from the aircraft.
This improvement is based on the SATLOCK System. Ground marker lines and teams
to assist in navigation are no longer required as in the past.
The
operation in Botswana was costed at US$ 278.00/km2 . This cost was
considered to be reasonable in view of the enormous reduction of the fly
population. It is hoped that aerial spraying will have a greater application as
a possible option to rapidly suppress tsetse populations prior to introducing
SIT in PATTEC projects.
A simple
density-dependent model to show the decrease in tsetse populations caused by
trapping was presented. The model was based on estimated parameters of efficacy
of trapping, strength of reinvasion and the equilibrium of populations affected
by the traps. The results of the model can be used in designing improved trap
barrier configurations to restrict invasions of tsetse into previously cleared
areas.
Work done
under the FITCA programme will improve the management of tsetse-transmitted
trypanosomosis in small scale dairy farms. Treatment of black mosquito net (75
denier) with beta-cyfluthrin prevented transmission of trypanosomosis. From
preliminary observations it appears that the protection will be effective in
highest risk areas. Externalities were recorded with less nuisance flies and
mosquitoes within a radius of at least 25 metres.
Chemosterilants
applied to traps are appropriate for use to suppress tsetse populations in
areas proposed for the final eradication using SIT. Triflumuron is known to be
effective in sterilising tsetse. However, the chemical affected cloth fabrics
differently. It had a greater effect on cotton and polypropylene fabric than on
polyester. This work highlights importance of selecting appropriate fabrics for
chemosterilisation with triflumuron.
RECOMMENDATIONS
1.
Recognizing
that community participation is important for the long term sustainability of
tsetse control, attempts should be taken to facilitate the involvement of local
communities in tsetse control programmes.
2.
Recognizing
the success of the recent aerial spraying operation in Botswana, PATTEC
Programmes should consider using the technique as an option for the rapid
suppression of tsetse control populations prior to implementing SIT. The choice
of technique should however be determined by the prevailing conditions in the
area selected for tsetse control.
3.
Modelling
of the impact of traps and targets on tsetse populations should be considered
as an important tool for estimating and predicting the effectiveness of
barriers to stop tsetse invasions into cleared areas.
4.
Tsetse
Control programmes should include an aspect of improved vector and disease
management strategies by the farmer prior to the total eradication of tsetse
flies. For example, farmers should be encouraged to use insecticide treated
nets to create tsetse/disease free zones in high trypanosomosis risk area.
Chairman :
Dr. Saini
Rapporteur : Dr. W. Olaho-Mukani
Seven
Papers were presented in the session. These ranged from attractants,
repellents, use of biological control agents and ecology.
A paper on
the impact of Triflumuron-treated male Glossina
palpalis gambiensis on female reproduction showed that the adopted method
was more effective in sterilizing female flies when increased doses of the
product were used. Since this product is already commercially available (Bayer)
it could easily be adopted for the integrated control of tsetse especially in
suppression activities preceding SIT application.
Presentation
on the feeding behaviour of tsetse attracted to herds of cattle revealed that
tsetse preferred feeding on older/larger animals, than young animals or cows.
However, interpretation of these observations must bear in mind the effect of
colour and the health status of animals in question. Other factors such as
tsetse response to odour must be taken into account too. The lack of
attractants for some riverine species of Glossina
fuscipes fuscipes was of major concern. Results on repellents as tools in
integrated tsetse management were encouraging but required further evaluation
especially as regards cost-effectiveness.
A paper on
the effect of neem extracts on tsetse behaviour showed encouraging results on
tsetse control but required further work.
Surveys
carried out in the Bhar-el-Jebel area revealed the presence of Glossina fuscipes fuscipes, but required more work to establish the extent of the
tsetse spread. Infectivity and development cycle of Trypanosoma suis EATRO 1864 in various Glossina species revealed that this isolate could have been
mistaken to be Trypanosoma suis and
further work was needed to establish its real identity.
RECOMMENDATIONS
1.
The
cost-effectiveness of biological control agents (fungi, bacteria, IGRS) needs
to be investigated and their potential integrated control of tsetse evaluated
fully.
2.
The
use of repellents as one of the tools in integrated tsetse control should be
further investigated.
3.
There
is a need to develop good baits/attractants for riverine species of tsetse and
strengthen the work already initiated on this aspect.
4.
The
implications of the observations that host colour, age and size may affect the
feeding behaviour of tsetse, further investigation was recommended on these
aspects.
5.
Detailed
studies on tsetse distribution in Southern Sudan were noted and it was
recommended that these be continued to define the distribution limits of the
flies involved in sleeping sickness transmission.
HYBRID STERILITY WITHIN GLOSSINA MORSITANS SUB-SPECIES AND GLOSSINA SWYNNERTONI
Moderateur : Issa
Sidibe
Rapporteur : Dethie Faye
The objective
of this study was to analyse hybridisation between G. swynnertoni and G.
morsitans sub-species specific questions were to determine sperm use in
multiple species-mated females and characterise the genetic vulnerability of G. swynnertoni populations. From this study, it appears that
hybridization reduces the fertility of the crosses by at least 50% and
reciprocal crosses showed hybridization asymmetry (HA). There was also a tendency for hybridized
females to recover fertility with time so that it is necessary to observe
females for more than 3 ovulation cycles.
The author underlines the necessity of a more detailed DNA analysis of sperm utilisation if multiple species mating is common in the field.
Moderateur : Issa Sidibe
Rapporteur : Dethie Faye
Two papers
were presented during this session.
The first one was given by David Bourn and draws attention to the cumulative and pervasive impacts of human activity on African landscapes, that have changed the nature of trypanosomosis over much of the Continent. He highlighted the importance of livestock in rural livelihoods and poverty reduction and examined the implications for sustainable, farmer focused disease control in the future.
Demographic
pressure and anthropogenic effects were reported by the author. These pressures
lend support to smaller-scale, farmer focused activities for disease control
with the formulation of disease control strategies tailored to the
specificities of individual sites. The
author ended by saying the most sustainable and farmer focused trypanosomosis
control in would be an integrated approach to reducing, including control in
future would be an integrated approach to reducing, including trypanotolerant
stock locally available options such as some use of trypanocidal drugs and
control of the vector.
The second
paper was about modelling of spatial bovine trypanosomosis in an agro-pastoral
zone of Burkina Faso.
The modelling was conducted with specific aim: to study the relationships between cattle trypanosomosis, vectors and hosts on the one hand and natural environment and animal production practices on the other. An integration of GIS data of this type opens a way for the identification of spatial indicators of a trypanosomal risk. However, the process used needs to be simplified for widespread use.
1.
GIS is
an important tool for use in data collection for prioritization of tsetse
control/eradication projects and planning and there is urgent need for capacity
building.
SOCIO-ECONOMIC PERSPECTIVES
Chairman : A. Ilemobade
Rapporteur : M. Kamuanga
A total of 5 papers were
presented on topics ranging from the effects of diseasecontrol on livestock
productivity (milk), the role of income generating activities to sustain
community-managed trypanosomosis, socio-economic factors affecting decision
support in the control of the disease, to the effects of climate, human
population and socio-economic changes on tsetse and trypanosomosis.
Results
from experiments have indicated the effects of trypanosomosis on milk yields
respectively in West African dwarf goats (The Gambia), in Zebu and in crossbred
cattle (Kenya). Trypanosomosis reduce lactation period but does not significantly
affect goat milk yield or offspring growth until the age of 3 months, while
deworming significantly improved goat productivity. Isometamidium prophylaxis
has a detrimental effect on milk production of Zebu cattle and crosses,
confirming claims made by farmers in the study area (Kenya). The level of
trypanosomosis challenge is shown to affect the results in the two experiments.
A case study of the Lambwe Valley (Kenya) underscored the major problem inherent in collective action in tsetse and trypanosomosis control i.e. on the ability of community members to sustain their interests