ProfessorMaria-GloriaBasanez

Researh Strands. My research has focused on a multidisciplinary approach involving the study of epidemiological, parasitological, and entomological patterns of human onchocerciasis in the field with the view of integrating these research strands into models of transmission dynamics.  Transmission of onchocerciasis is by Simulium blackflies.  Entomological determinants of epidemiological patterns are of particular interest.  For this work I collaborate with co-workers in Venezuela, Mexico, Guatemala, Ecuador, and African countries.  The different arms of the work come together in the development of mathematical models of onchocerciasis and other helminth infections such as schistosomiasis and soil-transmitted helminthiases.  Financial support for the research has been awarded by the Medical Research Council, UK through a Career Establishment Grant (2003-2008), the Royal Society Short Incoming Visits (2005)  and the Wellcome Trust (2009-2012).  Through this, I have been able to establish the Helminth Ecology Research Group. 

My interest in infectious blindness has brought about collaborations within DIDE and the LSHTM (Prof David Mabey's group at http://www.lshtm.ac.uk/people/mabey.david) for research on trachoma (funded by the International Trachoma Initiative), and my interest in vector-borne diseases has expanded into the population biology of malaria within the mosquito for the investigation of transmission-blocking strategies (funded by the EU FP7 framework).  Members of my group include Dr Tom Churcher, Dr Poppy Lamberton, Ms Emma Dawes, Mr Simon O'Hanlon, and Mr Martin Walker.  

Figure 1. The effective reproductive ratio (R_e) of Onchocerca volvulus as a function of mean microfilarial load. The coloured lines correspond to vector biting rates, with green to red indicating increasing vector abundance (recorded in the field as the no. of bites per person-year at each locality). The maximum value of R_e corresponds to the basic reproductive number, R₀. Mating probability is set equal to 1. The points at which the curves cross R_e=1 are the equilibrium parasite densities of the system.

Notice that for the West African vector (Simulium damnosum) there is a single, stable, non-trivial equilibrium above a threshold biting rate. For the vector in Guatemala and Mexico (S. ochraceum) there are two equilibria for each biting rate. The values on the left of maximum R_e represent unstable parasite densities.

Figure 2. Equilibrium microfilarial loads of O. volvulus in human communities for varying vector annual biting rates and values of the human blood index. The point at which the lines (model outputs) cross the x-axis represent the threshold or critical vector biting rates above which onchocerciasis is endemic. Notice that the critical biting rates for the main vector in Guatemala and Mexico (Simulium ochraceum) are, on average, 10 times as large as those of the main vector in West African savannah (S. damnosum). This can be explained by differing vector competence between the two species.

Teaching Activities. I have helped establish the Modern Epidemiology (MSc) course since its inception in 2001, and was the Course Organiser from 2001 to 2007.  During the first term of the course, I lecture on the principles of population dynamics, vector-borne infections, and macroparasite population biology.  During the second term, I coordinate an in-depth module that develops the subjects of epidemiology and control of vector-borne and helminthic diseases, including malaria, leishmaniasis, onchocerciasis, lymphatic filariasis, schistosomiasis and intestinal helminthiases.  I have supervised a number of MSc students whose final projects have culminated in publications in peer-review journals.  Examples are (students' names are highlighted):

Basáñez M-G, Pion SDS, Boakes E, Filipe JAN, Churcher TS & Boussinesq M (2008). Effect of single dose ivermectin on Onchocerca volvulus: a systematic review and meta-analysis. Lancet Infectious Diseases 8, 310-322.

Rudge JW, Stothard JR, Basáñez M-G, Mgenic AF, Khamis IS, Khamis AN & Rollinson D (2008). Micro-epidemiology of urinary schistosomiasis in northern Unguja (Zanzibar): risk factors associated with distribution of infections among schoolchildren and relevance for control. Acta Tropica 105, 45-54.

Sousa-Figueiredo JC, Basáñez M-G, Mgeni AF, Khamis IS, Rollinson D & Stothard JR (2008). A parasitological survey of preschool children and their mothers for urinary schistosomiasis, soil-transmitted helminthiasis and malaria in rural Zanzibar, with observations on prevalence of anaemia. Annals of Tropical Medicine and Parasitology 102, 679-692.

 French MD, Rollinson D, Basáñez M-G, Mgeni AF, Khamis IS & Stothard JR (2007). School-based control of urinary schistosomiasis on Zanzibar, Tanzania: monitoring micro-haematuria with reagent strips as a rapid urological assessment. Journal of Pediatric Urology 3, 364-368.

Basáñez M-G, Razali K, Renz A & Kelly D (2007). Density-dependent host choice by disease vectors: Epidemiological implications of the Ideal Free Distribution. Transactions of the Royal Society of Tropical Medicine and Hygiene 101, 256-269.

Wetten S, Collins RC, Vieira JC, Marshall C, Shelley AJ & Basáñez M-G (2007). Vector competence for Onchocerca volvulus in the Simulium (Notolepria) exiguum complex: cytoforms or density-dependence? Acta Tropica 103, 58-68.

Vieira JC, Brackenboro L, Porter CH, Basáñez M-G & Collins RC (2005). Temporal and spatial variation in biting rates and parasite transmission potentials of onchocerciasis vectors in Ecuador. Transactions of the Royal Society of Tropical Medicine and Hygiene 99, 178-195.

Other teaching activities include lecturing in the Third-year Epidemiology Course for the BSc in Biology (see http://www1.imperial.ac.uk/medicine/people/yaobi.zhang/), and the Short Course on Introduction to Mathematical Models of the Epidemiology & Control of Infectious Diseases, for which I run a project on vector-borne infections that includes malaria and filarial models.

Current Postgraduate (PhD) Students

1) Emma J Dawes http://www1.imperial.ac.uk/medicine/people/emma.dawes05/  

Dawes EJ, Zhuang S, Sinden RE & Basáñez M-G (2009). The temporal dynamics of Plasmodium density through the sporogonic cycle within Anopheles mosquitoes. Transactions of the Royal Society of Tropical Medicine and Hygiene [Epub ahead of print].

2) Michael D French http://www1.imperial.ac.uk/medicine/people/michael.french05/

Stothard JR, French MD, Khamis S, Basáñez M-G & Rollinson D (2009).The epidemiology and control of urinary schistosomiasis and soil-transmitted helminthiasis in schoolchildren on Unguja Island, Zanzibar. Transactions of the Royal Society of Tropical Medicine and Hygiene [Epub ahead of print].

3) James W Rudge

Rudge JW, Carabin H, Balolong E, Tallo V, Shrivastava J, Lu DB, Basáñez M-G, Olveda R, McGarvey ST & Webster JP (2008). Population genetics of Schistosoma japonicum within the Philippines suggest high levels of transmission between humans and dogs. PLoS Neglected Tropical Diseases 2(11), e340.

4) Martin Walker http://www1.imperial.ac.uk/medicine/people/m.walker06/ 

Walker M, Hall A, Anderson RM & Basáñez M-G (2009). Density-dependent constraints on the weight of female Ascaris lumbricoides infections of humans and its impact on patterns of egg production. Parasites and Vectors 2, 11.

Postdoctoral Research Associates

1) Dr Thomas S. Churcher http://www1.imperial.ac.uk/medicine/people/thomas.churcher/

Churcher TS & Basáñez M-G (2009). Sampling strategies to detect anthelmintic resistance: the perspective of human onchocerciasis. Trends in Parasitology 25, 11-17.

Churcher TS & Basáñez M-G (2008). Density dependence and the spread of anthelmintic resistance. Evolution  62, 528-537.

2) Dr Poppy Lamberton http://www1.imperial.ac.uk/medicine/people/poppy.lamberton/

Poppy Lamberton has started working on the Wellcome Trust-funded project on 'Host Choice by Onchocerciasis Vectors'.

Intra- and Inter-Faculty Collaborations

1) Dr. Mark P. Little http://www1.imperial.ac.uk/medicine/people/mark.little/

With Mark Little we have developed statistical models to explore the relationship between infection, morbidity, and mortality in human onchocerciasis:

Little MP, Breitling LP, Basáñez M-G, Alley ES, Boatin BA (2004). Association between microfilarial load and excess mortality in onchocerciasis: an epidemiological study. Lancet 363, 1514-1521.

Little MP, Basáñez M-G, Breitling LP, Boatin BA, Alley ES (2004). Incidence of blindness during the Onchocerciasis control programme in western Africa, 1971-2002. J Infect Dis 189, 1932-1941.

2) Prof Robert E. Sinden http://www3.imperial.ac.uk/people/r.sinden/

http://www.bio.imperial.ac.uk/research/res/sinden.htm

With Bob Sinden we are investigating the sources of density dependence in Plasmodium-Anopheles interactions and their implications for transmission-blocking strategies:

Sinden RE, Dawes EJ, Alavi Y, Waldock J, Finney O, Mendoza J, Butcher GA, Andrews L, Hill AV, Gilbert SC & Basáñez M-G (2007). Progression of Plasmodium berghei through Anopheles stephensi is density-dependent. PLoS Pathogens 3, e195.

3) Dr George Christophides http://www3.imperial.ac.uk/people/g.christophides/

With George Christophides I am a co-applicant for the EU-funded FP7 Health Framework Project: Blocking the Transmission of Malaria: the mosquito vector target (TransMalariaBloc), 2008-2012.

4) Prof Jacob Koella  http://www3.imperial.ac.uk/people/j.koella/

With Jacob Koella we will be developing evolutionary models to accompany the population dynamics models that will be devised with Tom Churcher for the TransMalariaBloc project. 

Collaborations within DIDE

1) Dr. Joanne Webster (Schistosomiasis Research Group)http://www1.imperial.ac.uk/medicine/people/joanne.webster/

With Jo Webster we are collaborating in the investigation of the zoonotic transmission of Schistosoma japonicum in China and the Philippines, and the development of mathematical models for schistosomiases, with James Rudge (S. japonicum), Tom Churcher, and Mike French (S. haematobium and S. mansoni):

Rudge JW, Da-Bing L, Guo-Ren Fang, Tian-Ping Wang, Basáñez M-G & Webster JP (2009). Parasite genetic differentiation by host species and habitat type: molecular epidemiology of Schistosoma japonicum in hilly and marshland areas of Anhui Province, China. Molecular Ecology [Epub ahead of print].

2) Prof. Alan Fenwick (Schistosomiasis Control Initiative) http://www1.imperial.ac.uk/medicine/people/a.fenwick/ 

With Alan Fenwick we are in the process of submitting an application to the WHO to establish a World Health Organization Collaborative Centre for Monitoring & Evaluation and Decisional Support to Neglected Tropical Disease Control Programmes.

3) Dr. Nicholas C Grassly (Disease Ecology Research Group) http://www1.imperial.ac.uk/medicine/people/n.grassly/

http://www1.imperial.ac.uk/medicine/people/isobel.blake02/

With Nick Grassly, Isobel Blake, and Manoj Gambhir we collaborate to develop mathematical models for the transmission and control of trachoma: 

Blake IM, Burton MJ, Bailey R, Solomon AW, West S, Muñoz B, Mabey D, Gambhir M, Basáñez M-G & Grassly NC (2009). Estimating household and community transmission of ocular Chlamydia trachomatis. PLoS Neglected Tropical Diseases 3, e401.

4) Dr. Manoj Gambhir http://www1.imperial.ac.uk/medicine/people/m.gambhir/

Gambhir M, Basáñez M-G, Turner F, Kumaresan J & Grassly NC. (2007). Trachoma transmission, infection, and control. Lancet Infectious Diseases 7, 420-427.

Gambhir M, Basáñez M-G, Burton MJ, Solomon AW, Bailey RL, Holland MJ, Blake IM, Donnelly CA, Jabr I, Mabey DC & Grassly NC (2009). The development of an age-structured model for trachoma transmission dynamics, pathogenesis and control. PLoS Neglected Tropical Diseases 3, e462.