Document not found! Please try again

Translating global health research aims into ... - Wiley Online Library

3 downloads 12033 Views 69KB Size Report
The 2008 conference on global health research in Bamako, ..... weight to calls for urg ent. AR. T scale-u p. Tropical Medicine and International Health volume 15 ...
Tropical Medicine and International Health

doi:10.1111/j.1365-3156.2009.02456.x

volume 15 no 3 pp 321–328 march 2010

Viewpoint

Translating global health research aims into action: the example of the ALPHA network* D. Maher1, S. Biraro1, V. Hosegood2, R. Isingo3, T. Lutalo4, P. Mushati5, B. Ngwira6, M. Nyirenda2, J. Todd7,8 and B. Zaba7,8 on behalf of the collaborators in the ALPHA network 1 2 3 4 5 6 7 8

MRC ⁄ UVRI Uganda Research Unit on AIDS, Entebbe, Uganda Africa Centre for Health and Population Studies ⁄ University of KwaZulu Natal, KwaZulu Natal, South Africa TAZAMA Project, National Institute of Medical Research, Mwanza, Tanzania Rakai Health Sciences Program, Entebbe, Uganda Manicaland HIV ⁄ STD Prevention Project, Harare, Zimbabwe Karonga Prevention Study, Chilumba, Malawi London School of Hygiene and Tropical Medicine, London, UK TAZAMA Project, National Institute of Medical Research, Mwanza, Tanzania

Summary

There is increasing consensus on the importance of strengthening global health research to meet health and development goals. Three key global health research aims are to ensure that research (i) addresses priority health needs, (ii) contributes to policy development, and (iii) adds value to investments in developing countries through South–South collaboration and capacity-strengthening in the South. The ALPHA network (Analysing Longitudinal Population-based HIV ⁄ AIDS data on Africa) is an illustrative example of how these global health research aims can be translated into action. The network facilitates additional collaborative HIV epidemiological research among six independent research projects in Africa studying population-based cohorts. Under the first of the earlier mentioned aims, the network addresses key epidemiology research issues in HIV ⁄ AIDS which are crucial to making progress and monitoring progress in the response against HIV ⁄ AIDS. Under the second aim, the network’s scientific programme of research has contributed to strengthening the evidence base on HIV epidemiology in Africa and has informed policy development in areas such as targeted HIV prevention, social support, monitoring epidemic response and epidemic forecasting. Under the third aim, investment in the network has added value to the research investment in the individual projects through capacity development among African researchers as well as through the collaborative research outputs of the individual projects. Lessons from the network are relevant to collaborations facing similar challenges in other areas of global health research. These include the importance of establishing transparent and efficient governance for research collaborations, developing advance consensus on data sharing, ensuring effective communication for networking and demonstrating the added value of research investment in South–South collaborations. keywords HIV, epidemiology

Introduction The 2008 conference on global health research in Bamako, Mali (Global Ministerial Forum on Research for Health 2008), was a significant milestone in building consensus on how to strengthen research to meet health and development goals (McKee 2008). Three key aims are to ensure *Analysing Longitudinal Population-based HIV ⁄ AIDS data on Africa.

ª 2010 Blackwell Publishing Ltd

that research (i) addresses priority health needs, (ii) contributes to policy development, and (iii) adds value to investments in developing countries through South–South collaboration and capacity-strengthening in the South. The ALPHA network (Analysing Longitudinal Populationbased HIV ⁄ AIDS data on Africa) is an illustrative example of how these research aims can be translated into action. The network facilitates additional HIV epidemiology research among six independent research projects in Africa studying population-based cohorts. In this article, we show 321

Tropical Medicine and International Health

volume 15 no 3 pp 321–328 march 2010

D. Maher et al. Translating global health research aims into action

how the network has translated the earlier mentioned three research aims into action, by (i) addressing priority research issues in HIV epidemiology, (ii) strengthening the evidence base on HIV epidemiology to inform policy development, and (iii) adding value to research investments in the projects through collaboration between them and through building capacity among African researchers. Lessons from the network are relevant for collaborations in other health research areas facing similar challenges. Background – why research on HIV epidemiology in Africa is important An effective response to HIV is a global priority, and subSaharan Africa faces the greatest challenge as the region with the biggest share of the global HIV burden and the least resources (financial, human and infrastructure). On account of resource constraints, it is imperative to ensure that responses to HIV ⁄ AIDS are based on the best possible evidence, including epidemiological evidence. Quantifying the size of the HIV burden is important to indicate the severity of the epidemic. Measuring the changes in burden over time indicates how the HIV epidemic evolves, which is important for understanding HIV population dynamics, and can reflect the extent of progress in HIV prevention and care. Also, quantifying the size of the burden draws attention to the scale of the problem, thereby helping to mobilise resources for HIV prevention, care and mitigation. Monitoring HIV risk factors and the extent and impact of HIV ⁄ AIDS is necessary for national and international planning purposes to ensure an effective response and mitigate the impact of HIV ⁄ AIDS on individuals, families and societies. The generation of reliable estimates of HIV incidence is key to understanding HIV epidemic trends. This is particularly true in the era of increasing access to antiretroviral therapy (ART) because prolonged survival results in increased HIV prevalence. There is as yet no reliable means of assessing HIV incidence other than direct measurement by repeated population surveys (WHO 2009, Todd et al. 2009). Population-based studies show how HIV affects an entire community, minimising the problems of selection bias inevitable in studies of individuals recruited in clinics or from occupational groups. Data from these communitybased cohort studies have thus become vitally important in determining the course of the epidemic and its demographic impact. The ALPHA network The ALPHA network was formed in 2005 in response to the need for research collaboration on HIV epidemiology 322

in sub-Saharan Africa. The network, now comprises six long-standing research projects (Table 1) in Africa, is funded by the Wellcome Trust and administered by the London School of Hygiene and Tropical Medicine. In studying community-based cohorts, the member projects share the following features: (i) regular collection of individually linked data on socio-demographic factors and HIV serostatus, (ii) willingness to share a mutually agreed minimum data set, and (iii) commitment to building skills and capacity among African researchers. Strength of the network is that the projects represent diverse settings in different phases of the HIV epidemic. While each project has its own particular areas of expertise and independent research agenda addressing issues of local, national and international relevance, the network adds value through comparative analysis of site-specific data and, where possible and meaningful, analysis of pooled data to strengthen the available evidence and reveal further insights into HIV epidemiology. Achieving the network’s aims in line with those to strengthen global health research The aims of the network were developed at its inception in 2005. They match aims identified in Bamako to strengthen global research to meet health and development goals (Anonymous 2008) (Table 2). Address priority research issues in HIV epidemiology by adding value to data analysis The network’s main activity is a scientific programme of workshops, developed by consensus among the projects. Each workshop focuses on a particular theme in HIV epidemiology and is hosted by one of the projects (Table 3). The workshops for member projects and invited ‘guest’ researchers involve lectures and group discussions about current concepts and analytical methods relevant to the particular theme. Facilitators, including experienced researchers and analysts from member projects, demonstrate data management and analyses using data from the host project processed using standard statistical packages. The preparation of data sets with an agreed common format enables easy application of statistical procedures. Facilitators assist participants with similar analyses using their own data. Results of analyses are compared across projects and, when possible, data are pooled and metaanalyses are undertaken. Creating and analysing pooled data sets strengthen analytical conclusions and increase the representativeness of data from individual studies. The background data on demographic, residential and socioeconomic factors which are ‘adjusted for’ in risk factor and

ª 2010 Blackwell Publishing Ltd

ª 2010 Blackwell Publishing Ltd

UK Medical Research Council ⁄ Uganda Virus Research Institute Uganda Virus Research Institute, Makarere University Tanzania National Institute for Medical Research

London School of Hygiene and Tropical Medicine

Biomedical Research and Training Institute, Harare, Imperial College London

Africa Centre for Health and Population Studies ⁄ University of KwaZulu Natal

Masaka General Population Cohort Rakai Health Science Program TAZAMA project: Kisesa cohort

Karonga Prevention Study

Manicaland HIV ⁄ STD Prevention Project

Umkhanyakude cohort

2003

1998

1988

1994

1994

1989

Start year Twenty villages in Masaka district, Uganda Fifty communities in Rakai district, Uganda Six villages in Magu district, Mwanza region, Tanzania Twenty five community clusters near Chilumba, Karonga district, Malawi Twelve communities, stratified by socio-economic setting Manicaland, Zimbabwe Umkhanyakude district in northern KwaZulu Natal, South Africa

Site location

2003, 2005 and 2006

1999, 2002, 2004

Retrospect 1988, pilot 2005, baseline 2007

approximately every 3 years since 1994

Annual since 1995

Annual since 1989

Sero-survey timing

*Demographic surveillance totals include children for whom HIV status is not measured in most studies.

Institutional affiliation

Name of research project

Table 1 The ALPHA network research projects

Half yearly

Same as sero-survey

86 000

30 000

32 000

28 000

approximately half yearly

Continuous since 2002

14 000

7 000

Cohort size in 2008*

Annual

Annual

Demographic surveillance

430 000

90 000

150 000

350 000

168 000

115 000

Approx person-years obs*

22% (2003)

22.9% (1999) 20.0% (2002) 18.0% (2004) (av. all strata)

6.0% (1994) 8.3% (2000) 7.3% (2006, provisional) 3.8% (1988) 7.5% (2007, provisional)

8.5% (1990) 6.5% (2000) 7.7% (2005) 17.7% (1995) 12.8% (2003)

HIV prevalence (trend) in adult population

Tropical Medicine and International Health volume 15 no 3 pp 321–328 march 2010

D. Maher et al. Translating global health research aims into action

323

Tropical Medicine and International Health

volume 15 no 3 pp 321–328 march 2010

D. Maher et al. Translating global health research aims into action

Table 2 ALPHA network aims and those to strengthen global health research ALPHA network aims

Aims in strengthening global health research

Address priority research issues in HIV epidemiology by adding value to data analysis Strengthen the evidence base on HIV epidemiology to inform policy development Build capacity in epidemiological research (data analysis and interpretation) through South–South collaboration and capacity-strengthening in the South

Ensure research addresses priority health needs

intervention analyses can also be studied in depth. Participants discuss and describe the implications of the findings. Articles are finalised later with mentor support (including site visits and e-mail consultation) and through visits between member projects. Articles from each workshop have been presented at conferences and published in special journal issues on the workshop themes (Ghys et al. 2007; Gregson et al. 2009). Strengthen the evidence base on HIV epidemiology to inform policy development The scientific programme of ALPHA workshops has generated research findings with important policy implications (Table 3). The network also contributed to the development and refinement of the model used by UNAIDS to generate its 2007 estimates of worldwide HIV prevalence by providing a standardised set of data representing inputs from a diverse range of sites in sub-Saharan Africa (UNAIDS & WHO 2007). The UNAIDS global estimates and projections of HIV infections are used to track progress in the global response to the HIV epidemic and inform strategic decisions on response priorities, including in generating and allocating resources (UNAIDS 2009). The network has so far generated 13 collaborative research publications and assisted member projects with 21 site-specific publications, with others in preparation. A full list of articles published on work carried out by the network is available on the ALPHA website (http://www.lshtm. ac.uk/cps/alpha). Build capacity in epidemiological research (data analysis and interpretation) In view of the human resource and infrastructure constraints in sub-Saharan Africa, conducting epidemiological surveillance and analysis must involve building capacity and skills to enable long-term sustainable monitoring. Workshop participants have shared expertise in developing practical skills in data management, including cleaning and preparing data before analysis, epidemio-

324

Ensure research contributes to policy development Maximise the value of research investments in developing countries through South–South collaboration and capacity-strengthening in the South

logical and demographic analysis methods, advanced programming techniques using the stata package (Stata Corp., TX, USA) and interpreting and presenting findings. Other means of developing these skills have included exchange visits between research groups, mentoring by experienced researchers and support for project staff to present their findings at scientific conferences. Research funders, e.g. the Wellcome Trust, recognise the value of building networks, especially in developing countries where the critical mass of researchers needed to develop new programmes may not be present in one location (Wellcome Trust and Tanzania National Institute of Medical Research 2008). Meeting challenges – lessons for international research collaborations Lessons from the network are relevant for international research collaborations in other areas of health research facing similar challenges, e.g. in governance, data sharing, communication for networking and funding. Regarding governance, efficient network functioning requires agreement between collaborators on management and scientific direction. ALPHA network governance relies on a Scientific Advisory Committee (comprising project leaders and external advisors) which approves the scientific programme, monitors progress and advises on dissemination of research results. Formal constitution of the SAC ensures transparency of processes and consideration of concerns of all projects. Expectations varied among the projects as to the order in which findings (from individual projects vs. from the network) could be published. Because data sharing can be a contentious issue, explicit agreements are necessary among collaborators (Wellcome Trust & WHO 2008). The ALPHA projects’ lead investigators signed agreements specifying which data would be shared among the projects and how the data contributed would be used. Technical challenges in constructing the pooled data set included ensuring comparability of data collected in different ways from the different projects. A documenta-

ª 2010 Blackwell Publishing Ltd

ª 2010 Blackwell Publishing Ltd

Presentation at HEARD conference Durban (2006). One publication.

Presentation at International AIDS Society conference (Mexico, 2008). Thirteen articles published in special issue of journal ‘AIDS’.

Impact of HIV on household and family structure: (i) household typology; (ii) children’s living arrangements; (iii) family change analysis.

HIV mortality and patterns of survival: (i) censoring problems in different types of cohort; (ii) parametric regression techniques; (iii) ‘net’ HIV mortality; (iv) age-specific mortality patterns for all infected persons.

Somkhele, South Africa, June 2006 (Africa Centre for Health and Population Studies ⁄ University of KwaZulu Natal)

Entebbe, Uganda, November 2006 (MRC ⁄ UVRI Uganda Research Unit on AIDS) N.B. Workshop included ‘guest researchers’ from several occupational and clinic-based cohorts (Murray et al. 2007; Peters et al. 2007) and some studies from outside Africa (Rangsin et al. 2007; Nelson et al. 2007)

A new methodology to adjust for background mortality when measuring changes in survival (Marston et al. 2007) showed that the worse prognosis of HIV infection occurring at an older age is because of a direct effect of HIV rather than to non-HIV-related causes at older ages. Longer survival post-infection in African countries, Thailand and Haiti (Todd et al. 2007) was possibly associated with the dominant viral subtype. Sites had similar age-specific HIV mortality patterns, with longer survival associated with an epidemic in declining phase.

National HIV forecasting and planning needs to take into consideration a country’s HIV epidemic phase.

Understanding host responses to viral subtypes in different parts of the world is important for HIV vaccine development.

Social support policies need to reflect the social context of the impact of HIV ⁄ AIDS and of household responses. Social support programmes need to consider a shift of current high levels of funding support from child-headed households towards families (Hosegood 2009). National HIV ⁄ AIDS Programmes need to ensure that older age groups are also included as a target for HIV prevention and care interventions and that people are aware of the extra risk of HIV infection with increasing age.

More accurate estimates of age-specific incidence enable better tracking of the epidemic and its response to interventions targeting particular age groups.

National HIV ⁄ AIDS Programmes need to redesign HIV prevention messages to target these sub groups at increased HIV risk.

In addition to the usual peak of HIV incidence among 20–30-year olds, in several sites, a secondary peak in incidence was documented in older age groups, mainly in widowed and divorced persons (Zaba et al. 2008). Direct measurement of incidence from individual sero-conversions in cohorts was used to validate new mathematical techniques for estimating age-specific incidence (Hallett et al. 2008). Study populations show considerable heterogeneity in social and residential arrangements. Child-headed households were extremely rare in all study populations.

Presentations at International AIDS Society conference (Toronto 2006 and Mexico 2008). Four publications.

Measuring age patterns of HIV incidence and prevalence: (i) methods for analysing longitudinal data; (ii) cumulative infection risk and age patterns of risk.

Mwanza, Tanzania, October 2005 (TAZAMA)

Implications for health policy

Research findings

Research outputs

Theme: topics

Venue, date (host)

Table 3 Scientific programme of workshops with main research findings

Tropical Medicine and International Health volume 15 no 3 pp 321–328 march 2010

D. Maher et al. Translating global health research aims into action

325

326 Theme: topics Sexual behaviour (especially timing of events, e.g. sexual debut): (i) using longitudinal data to evaluate reporting consistency; (ii) trends in age at first sex and age at first marriage.

Uptake and impact of voluntary counselling and testing (VCT) for HIV and of antiretroviral therapy (ART)

Venue, date (host)

Nyanga, Zimbabwe, September 2007 (Manicaland HIV ⁄ STD Prevention Project)

Mzuzu, Malawi, November 2008 (Karonga Prevention Study)

Table 3 (Continued)

In all sites, HIV-related deaths fell as a proportion of all deaths after the introduction of ART.

Data from longitudinal cohorts rather than cross-sectional surveys enable evaluation of consistency of reporting of sexual behaviour. In some study sites, age at sexual debut was reported more consistently than age at first marriage, and the inconsistent reports represented random noise rather than progressive bias that changed over time (Gregson et al. 2009; Wringe et al. 2009; Marston et al. 2009). After age standardisation, VCT uptake was higher amongst the ever-married, educated, more urban population groups. The main barrier to ART access was VCT uptake, although many of those testing positive did not take up referral to ART clinics.

Eleven articles published in special issue of journal ‘Sexually Transmitted Infections’.

Four presentations at IUSSP Marrakech 2009 international conference; and 14 articles in preparation for special journal issue.

Research findings

Research outputs

Intensified efforts are needed to ensure access to VCT among those never married, less well educated or living in rural areas. Priorities in expanding ART access include making HIV testing more widely and readily available and strengthening referral after VCT for ART. Evidence of ART impact in diverse settings adds weight to calls for urgent ART scale-up.

Trends in age at first sex derived from cross-sectional surveys (e.g. Demographic and Health Survey) can be taken at face value without further adjustment. Accurate determination of these trends is important because they are used to measure the success of campaigns promoting teenage abstinence.

Implications for health policy

Tropical Medicine and International Health volume 15 no 3 pp 321–328 march 2010

D. Maher et al. Translating global health research aims into action

ª 2010 Blackwell Publishing Ltd

Tropical Medicine and International Health

volume 15 no 3 pp 321–328 march 2010

D. Maher et al. Translating global health research aims into action

tion system was developed which provided an explanation of the nature of the data in the pooled data set, and a record of the processes through which the pooled data were abstracted from data held by the individual projects. This enabled updating of the pooled data set whenever project data were updated. The lesson is that technical challenges in international research collaborations can be met by pooling expertise, as well as data, from collaborating sites. Effective communication for networking requires good coordination. The ALPHA network secretariat coordinates the collaborative activities among the six projects, provides administrative services for network activities and facilitates communication. Complementing the personal interaction among researchers at workshops, interaction between researchers is also facilitated by telephone, e-mail and the network website (http:// www.lshtm.ac.uk/cps/alpha/). Overcoming communication infrastructure problems in developing countries may require investment in computers and internet access to facilitate networking among researchers in remote rural areas. Developing countries often face a Catch-22 situation in research funding. They often need a certain level of research capacity to attract research funding from developed countries, but developing research capacity itself depends on external funding from developed countries, and so is not easily achievable. Research groups in developing countries need to take advantage of the opportunities for South–South collaboration linked to existing North–South partnerships. The ALPHA network represents a good example of value for money because investment in the network’s activities has added value to the research investment in individual member projects. The future – what next for the ALPHA network? The ALPHA network has contributed to a strengthened evidence base in HIV epidemiology to inform policy and has built capacity in epidemiological analysis. The first 4 years’ activity provides a sound platform to address further important topics in HIV epidemiology. In future, proposed topics to be addressed may include the impact of HIV on fertility; the impact of HIV on child mortality; sexual partnership dynamics and the impact of antiretroviral therapy on HIV transmission and on HIV-related mortality. The intention is that for each workshop, involvement of the national HIV ⁄ AIDS programme of the host country will facilitate the process of developing and disseminating the policy implications arising from the workshop findings. The network faces challenges in

ª 2010 Blackwell Publishing Ltd

maintaining funding, identifying new ways to maximise the value of research investments, developing shared resource data set documentation, capitalising on achievements in capacity building, enlarging to embrace new projects and widening the range of international stakeholders beyond UNAIDS to include other agencies, e.g. UNICEF and UNFPA. Conclusion The ALPHA network is an example of how to translate global health research aims into action, providing useful lessons for those facing similar challenges in other health areas beyond HIV. Research funders have a crucial role in investing in epidemiological research, such as that conducted by the ALPHA network, which supports South– South collaboration and capacity development in the South and contributes to meeting health and development goals. References Anonymous (2008) The state of health research worldwide. Lancet 372, 1519. Ghys P, Zaba B & Prins M (2007) Survival and mortality of people infected with HIV in low and middle income countries – results from the extended ALPHA network. AIDS 21(Suppl. 6), S1–S4. Global Ministerial Forum on Research for Health (2008) The Bamako call to action on research for health. Strengthening research for health, development and equity. http://www. bamako2008.org/dmdocuments/CTA_3.pdf. Gregson S, Todd J & Zaba B (2009) Sexual behaviour change in countries with generalised HIV epidemics? Evidence from population-based cohort studies in sub-Saharan Africa. Sexually transmitted infections 85, i1–i2. Hallett TB, Zaba B, Todd J et al. on behalf of the ALPHA Network (2008) Estimating incidence from prevalence in generalised HIV epidemics: methods and validation. PLoS Medicine 5, 611–622. Hosegood V (2009) Demographic impact of HIV and AIDS on the family and household life-cycle: implications for strengthening families. AIDS Care 21, 13–21. Marston M, Todd J, Glynn JR & Zaba B (2007) ‘‘Net’’ mortality methods with comparison and summary of HIV-specific ‘‘Net survival’’. AIDS 21, S65–S71. Marston M, Slaymaker E, Cremin I et al. (2009) Trends in marriage and time spent single in sub-Saharan Africa: a comparative analysis of six population-based cohort studies and nine Demographic and Health Surveys. Sexually transmitted infections 85, i64–i71. McKee M (2008) Global research for health. Should tackle health needs and inform policy. British Medical Journal 337, 1249– 1250.

327

Tropical Medicine and International Health

volume 15 no 3 pp 321–328 march 2010

D. Maher et al. Translating global health research aims into action

Murray J, Sonnenberg P, Nelson G, Bester A, Shearer S & Glynn JR (2007) Cause of death and presence of respiratory disease at autopsy in an HIV-1 seroconversion cohort of Southern African gold miners. AIDS 21(Suppl. 6), S97–S104. Nelson KE, Costello C, Suriyanon V, Sennun S & Duerr A (2007) Survival after HIV-1 subtype E (CRF01 A_E) among blood donors and their spouses in northern Thailand. AIDS 21(Suppl. 6), S47–S54. Peters PJ, Meinzen-Derr J, Karita E et al. for the Rwanda-Zambia HIV Research Group (2007) HIV-infected Rwandan women have a high frequency of long-term survival. AIDS 21 (Suppl. 6), S31–S37. Rangsin R, Piyaraj P, Sirisanthana T, Sirisopana N, Short O & Nelson KE (2007) The natural history of HIV-1 subtype E infections in young men in Thailand with up to 14 years of follow-up. AIDS 21(Suppl. 6), 6. Todd J, Glynn JR, Marston M et al. (2007) Time from HIV sero-conversion to death prior to ART: a collaborative analysis of eight studies in six developing countries. AIDS 21, S55–S63. Todd J, Lutalo T & Kaleebu P (2009) Estimating incidence of HIV infection in Uganda (Letter). Journal of the American Medical Association 301, 159–160.

UNAIDS (2009) Reference Group on Estimates, Modelling and Projections. http://www.epidem.org/ (accessed 10 September 2009). UNAIDS & WHO (2007). AIDS Epidemic Update: December 2007. WHO, Geneva. Wellcome Trust and Tanzania National Institute of Medical Research (2008) Meeting report. Cohorts and prospective studies – a North-South networking meeting. Arusha, Tanzania. 7–9 January 2008. Wellcome Trust & WHO (2008) Sharing Public Health Data: a code of conduct. Paper presented at 2008 conference on global health research in Bamako, Mali. WHO (2009) WHO Working Group on HIV Incidence. (http:// www.who.int/diagnostics_laboratory/links/hiv_incidence_assay/ en/index1.html) (accessed 10 September 2009). Wringe A, Cremin I, Herbst K et al. (2009) A comparative assessment of the quality of age at event reporting in three HIV cohort studies in sub-Saharan Africa. Sexually transmitted infections 85, i56–i63. Zaba B, Todd J & Biraro S et al.. (2008) ALPHA Network. Diverse Age Patterns of HIV Incidence Rates in Africa. Abstract TUAC0201, XVII International AIDS Conference, Mexico, August 2008.

Corresponding Author Dermot Maher, MRC ⁄ UVRI Uganda Research Unit on AIDS, PO Box 49, Entebbe, Uganda. Tel.: +256 775515461; E-mail: [email protected]

328

ª 2010 Blackwell Publishing Ltd