Skip to main content
Dryad

The impact of within-host coinfection interactions on between-host parasite transmission dynamics varies with spatial scale

Cite this dataset

Keegan, Shaun; Pedersen, Amy; Fenton, Andrew (2024). The impact of within-host coinfection interactions on between-host parasite transmission dynamics varies with spatial scale [Dataset]. Dryad. https://doi.org/10.5061/dryad.tdz08kq68

Abstract

Within-host interactions among coinfecting parasites can have major consequences for individual infection risk and disease severity. However, the impact of these within-host interactions on between-host parasite transmission, and the spatial scales over which they occur, remain unknown. We developed and applied a novel spatially explicit analysis to parasite infection data from a wild wood mouse (Apodemus sylvaticus) population. We previously demonstrated a strong within-host negative interaction between two wood mouse gastrointestinal parasites, the nematode Heligmosomoides polygyrus, and the coccidian Eimeria hungaryensis, using drug-treatment experiments. Here, we show this negative within-host interaction can significantly alter the between-host transmission dynamics of E. hungaryensis, but only within spatially-restricted neighbourhoods around each host. However, for the closely related species E. apionodes, which experiments show does not interact strongly with H. polygyrus, we did not find any effect on transmission over any spatial scale. Our results demonstrate that the effects of within-host coinfection interactions can ripple out beyond each host to alter the transmission dynamics of the parasites, but only over local scales that likely reflect the spatial dimension of transmission. Hence there may be knock-on consequences of drug treatments impacting the transmission of non-target parasites, altering infection risks even for non-treated individuals in the wider neighbourhood.

README: The impact of within-host coinfection interactions on between-host parasite transmission dynamics varies with spatial scale ? ?️

Overview ?

These data were collected in 2012 as part of a broader piece of work exploring the parasite communities of the wood mouse (Apodemus sylvaticus). This code base takes input data from trapping grids and calculates neighbourhood prevalence relative to each individual on the grid. It does this by iteratively identifying each individual in the population as the ‘focal’ individual, and each other as a potential neighbour, with a distance to the focal individual calculated. Then neighbourhood prevalence and mean infection burden of the potentially interacting parasite (the nematode Heligmosomoides polygyrus) are calculated for each user-defined neighbourhood size around the focal individual. These are then able to be used in statistical models as an explanatory factor for the specified infection state (Eimeria presence/absence or intensity) of all focal individuals.

Input Data Structure ?

The core data, included in raw data.csv includes:

• Animal identifier

• Temporal data in DD/MM/YYYY format

• X & Y grid coordinates

• Animal demographic data

• Parasitological data

And more specifically:

Variable Name Description
ID ID code assigned to animal
ID.CapDate ID code assigned to animal combined with capture date
X X coordinates on the grid
Y X coordinates on the grid
Capture.date Temporal data in DD/MM/YYYY format
Grid Grid Designation
Year Capture Year
Sex Mouse Sex (M/F/NA)
Age Mouse Age (Adult/NotAdult/NA)
treated.Y.N Whether an animal has been treated with the anthelmintic ivermectin (0/1)
EhungInt Infection intensity of E. hungaryensis
EhungInf Presence or absence of E. hungaryensis (0/1)
EappInt Infection intensity of E. apionoides
EappInf Presence or absence of E. apionoides (0/1)
H.poly.EPG Infection intensity of H. polygyrus
HpolINF Presence or absence of H. polygyrus (0/1)

Output Data Structure - neighbourhood data generation

These files are titled:

DATA - Eapp_17.csv,DATA - Eapp_34.csv,DATA - Eapp_51.csv, DATA - Eapp_all.csv, DATA - Ehung_17.csv, DATA - Ehung_34.csv, DATA - Ehung_51.csv, DATA - Ehung_all.csv

Each file will have all of the following fields:

Variable Name Description
ID ID code assigned to animal
ID.CapDate ID code assigned to animal combined with capture date
X X coordinates on the grid
Y X coordinates on the grid
Capture.date Temporal data in DD/MM/YYYY format
Grid Grid Designation
Year Capture Year
Sex Mouse Sex (M/F/NA)
Age Mouse Age (Adult/NotAdult/NA)
treated.Y.N Whether an animal has been treated with the anthelmintic ivermectin (0/1)
H.poly.EPG Infection intensity of H. polygyrus
HpolINF Presence or absence of H. polygyrus (0/1)

And files with "Ehung" in the file name will have:

Variable Name Description
EhungInt Infection intensity of E. hungaryensis
EhungInf Presence or absence of E. hungaryensis (0/1)

While files with "Eapp" in the file name will have:

Variable Name Description
EappInt Infection intensity of E. apionoides
EappInf Presence or absence of E. apionoides (0/1)

All files will have the following fields:

Term Description
PropOnGrid_10 Proportion of the neighbourhood on the grid at 10 metre radius around the focal host
NemNoInf_10 Number of individuals infected with H. polygyrus on the neighbourhood at 10 metre radius around the focal host
NemNoUninf_10 Number of individuals not infected with H. polygyrus on the neighbourhood at 10 metre radius around the focal host
NemPrev_10 Prevalence of H. polygyrus on the neighbourhood at 10 metre radius around the focal host
NemNoTotal_10 Number of hosts in the neighbourhood with H. polygyrus at 10 metre radius around the focal host
NemTotBurden_10 Total burden of H. polygyrus on the neighbourhood at 10 metre radius around the focal host
NemMeanBurden_10 Mean burden of H. polygyrus on the neighbourhood at 10 metre radius around the focal host
EimNoInf_10 Number of individuals infected with Eimeria on the neighbourhood at 10 metre radius around the focal host
EimNoUninf_10 Number of individuals not infected with Eimeria on the neighbourhood at 10 metre radius around the focal host
EimPrev_10 Prevalence of Eimeria on the neighbourhood at 10 metre radius around the focal host
EimNoTotal_10 Number of hosts in the neighbourhood with Eimeria at 10 metre radius around the focal host
PropOnGrid_14.1 Proportion of the neighbourhood on the grid at 14.1 metre radius around the focal host
NemNoInf_14.1 Number of individuals infected with H. polygyrus on the neighbourhood at 14.1 metre radius around the focal host
NemNoUninf_14.1 Number of individuals not infected with H. polygyrus on the neighbourhood at 14.1 metre radius around the focal host
NemPrev_14.1 Prevalence of H. polygyrus on the neighbourhood at 14.1 metre radius around the focal host
NemNoTotal_14.1 Number of hosts in the neighbourhood with H. polygyrus at 14.1 metre radius around the focal host
NemTotBurden_14.1 Total burden of H. polygyrus on the neighbourhood at 14.1 metre radius around the focal host
NemMeanBurden_14.1 Mean burden of H. polygyrus on the neighbourhood at 14.1 metre radius around the focal host
EimNoInf_14.1 Number of individuals infected with Eimeria on the neighbourhood at 14.1 metre radius around the focal host
EimNoUninf_14.1 Number of individuals not infected with Eimeria on the neighbourhood at 14.1 metre radius around the focal host
EimPrev_14.1 Prevalence of Eimeria on the neighbourhood at 14.1 metre radius around the focal host
EimNoTotal_14.1 Number of hosts in the neighbourhood with Eimeria at 14.1 metre radius around the focal host
PropOnGrid_20 Proportion of the neighbourhood on the grid at 20 metre radius around the focal host
NemNoInf_20 Number of individuals infected with H. polygyrus on the neighbourhood at 20 metre radius around the focal host
NemNoUninf_20 Number of individuals not infected with H. polygyrus on the neighbourhood at 20 metre radius around the focal host
NemPrev_20 Prevalence of H. polygyrus on the neighbourhood at 20 metre radius around the focal host
NemNoTotal_20 Number of hosts in the neighbourhood with H. polygyrus at 20 metre radius around the focal host
NemTotBurden_20 Total burden of H. polygyrus on the neighbourhood at 20 metre radius around the focal host
NemMeanBurden_20 Mean burden of H. polygyrus on the neighbourhood at 20 metre radius around the focal host
EimNoInf_20 Number of individuals infected with Eimeria on the neighbourhood at 20 metre radius around the focal host
EimNoUninf_20 Number of individuals not infected with Eimeria on the neighbourhood at 20 metre radius around the focal host
EimPrev_20 Prevalence of Eimeria on the neighbourhood at 20 metre radius around the focal host
EimNoTotal_20 Number of hosts in the neighbourhood with Eimeria at 20 metre radius around the focal host
PropOnGrid_22.4 Proportion of the neighbourhood on the grid at 22.4 metre radius around the focal host
NemNoInf_22.4 Number of individuals infected with H. polygyrus on the neighbourhood at 22.4 metre radius around the focal host
NemNoUninf_22.4 Number of individuals not infected with H. polygyrus on the neighbourhood at 22.4 metre radius around the focal host
NemPrev_22.4 Prevalence of H. polygyrus on the neighbourhood at 22.4 metre radius around the focal host
NemNoTotal_22.4 Number of hosts in the neighbourhood with H. polygyrus at 22.4 metre radius around the focal host
NemTotBurden_22.4 Total burden of H. polygyrus on the neighbourhood at 22.4 metre radius around the focal host
NemMeanBurden_22.4 Mean burden of H. polygyrus on the neighbourhood at 22.4 metre radius around the focal host
EimNoInf_22.4 Number of individuals infected with Eimeria on the neighbourhood at 22.4 metre radius around the focal host
EimNoUninf_22.4 Number of individuals not infected with Eimeria on the neighbourhood at 22.4 metre radius around the focal host
EimPrev_22.4 Prevalence of Eimeria on the neighbourhood at 22.4 metre radius around the focal host
EimNoTotal_22.4 Number of hosts in the neighbourhood with Eimeria at 22.4 metre radius around the focal host
PropOnGrid_28.3 Proportion of the neighbourhood on the grid at 28.3 metre radius around the focal host
NemNoInf_28.3 Number of individuals infected with H. polygyrus on the neighbourhood at 28.3 metre radius around the focal host
NemNoUninf_28.3 Number of individuals not infected with H. polygyrus on the neighbourhood at 28.3 metre radius around the focal host
NemPrev_28.3 Prevalence of H. polygyrus on the neighbourhood at 28.3 metre radius around the focal host
NemNoTotal_28.3 Number of hosts in the neighbourhood with H. polygyrus at 28.3 metre radius around the focal host
NemTotBurden_28.3 Total burden of H. polygyrus on the neighbourhood at 28.3 metre radius around the focal host
NemMeanBurden_28.3 Mean burden of H. polygyrus on the neighbourhood at 28.3 metre radius around the focal host
EimNoInf_28.3 Number of individuals infected with Eimeria on the neighbourhood at 28.3 metre radius around the focal host
EimNoUninf_28.3 Number of individuals not infected with Eimeria on the neighbourhood at 28.3 metre radius around the focal host
EimPrev_28.3 Prevalence of Eimeria on the neighbourhood at 28.3 metre radius around the focal host
EimNoTotal_28.3 Number of hosts in the neighbourhood with Eimeria at 28.3 metre radius around the focal host
PropOnGrid_30 Proportion of the neighbourhood on the grid at 30 metre radius around the focal host
NemNoInf_30 Number of individuals infected with H. polygyrus on the neighbourhood at 30 metre radius around the focal host
NemNoUninf_30 Number of individuals not infected with H. polygyrus on the neighbourhood at 30 metre radius around the focal host
NemPrev_30 Prevalence of H. polygyrus on the neighbourhood at 30 metre radius around the focal host
NemNoTotal_30 Number of hosts in the neighbourhood with H. polygyrus at 30 metre radius around the focal host
NemTotBurden_30 Total burden of H. polygyrus on the neighbourhood at 30 metre radius around the focal host
NemMeanBurden_30 Mean burden of H. polygyrus on the neighbourhood at 30 metre radius around the focal host
EimNoInf_30 Number of individuals infected with Eimeria on the neighbourhood at 30 metre radius around the focal host
EimNoUninf_30 Number of individuals not infected with Eimeria on the neighbourhood at 30 metre radius around the focal host
EimPrev_30 Prevalence of Eimeria on the neighbourhood at 30 metre radius around the focal host
EimNoTotal_30 Number of hosts in the neighbourhood with Eimeria at 30 metre radius around the focal host
PropOnGrid_31.6 Proportion of the neighbourhood on the grid at 31.6 metre radius around the focal host
NemNoInf_31.6 Number of individuals infected with H. polygyrus on the neighbourhood at 31.6 metre radius around the focal host
NemNoUninf_31.6 Number of individuals not infected with H. polygyrus on the neighbourhood at 31.6 metre radius around the focal host
NemPrev_31.6 Prevalence of H. polygyrus on the neighbourhood at 31.6 metre radius around the focal host
NemNoTotal_31.6 Number of hosts in the neighbourhood with H. polygyrus at 31.6 metre radius around the focal host
NemTotBurden_31.6 Total burden of H. polygyrus on the neighbourhood at 31.6 metre radius around the focal host
NemMeanBurden_31.6 Mean burden of H. polygyrus on the neighbourhood at 31.6 metre radius around the focal host
EimNoInf_31.6 Number of individuals infected with Eimeria on the neighbourhood at 31.6 metre radius around the focal host
EimNoUninf_31.6 Number of individuals not infected with Eimeria on the neighbourhood at 31.6 metre radius around the focal host
EimPrev_31.6 Prevalence of Eimeria on the neighbourhood at 31.6 metre radius around the focal host
EimNoTotal_31.6 Number of hosts in the neighbourhood with Eimeria at 31.6 metre radius around the focal host
PropOnGrid_36.1 Proportion of the neighbourhood on the grid at 36.1 metre radius around the focal host
NemNoInf_36.1 Number of individuals infected with H. polygyrus on the neighbourhood at 36.1 metre radius around the focal host
NemNoUninf_36.1 Number of individuals not infected with H. polygyrus on the neighbourhood at 36.1 metre radius around the focal host
NemPrev_36.1 Prevalence of H. polygyrus on the neighbourhood at 36.1 metre radius around the focal host
NemNoTotal_36.1 Number of hosts in the neighbourhood with H. polygyrus at 36.1 metre radius around the focal host
NemTotBurden_36.1 Total burden of H. polygyrus on the neighbourhood at 36.1 metre radius around the focal host
NemMeanBurden_36.1 Mean burden of H. polygyrus on the neighbourhood at 36.1 metre radius around the focal host
EimNoInf_36.1 Number of individuals infected with Eimeria on the neighbourhood at 36.1 metre radius around the focal host
EimNoUninf_36.1 Number of individuals not infected with Eimeria on the neighbourhood at 36.1 metre radius around the focal host
EimPrev_36.1 Prevalence of Eimeria on the neighbourhood at 36.1 metre radius around the focal host
EimNoTotal_36.1 Number of hosts in the neighbourhood with Eimeria at 36.1 metre radius around the focal host
PropOnGrid_40 Proportion of the neighbourhood on the grid at 40 metre radius around the focal host
NemNoInf_40 Number of individuals infected with H. polygyrus on the neighbourhood at 40 metre radius around the focal host
NemNoUninf_40 Number of individuals not infected with H. polygyrus on the neighbourhood at 40 metre radius around the focal host
NemPrev_40 Prevalence of H. polygyrus on the neighbourhood at 40 metre radius around the focal host
NemNoTotal_40 Number of hosts in the neighbourhood with H. polygyrus at 40 metre radius around the focal host
NemTotBurden_40 Total burden of H. polygyrus on the neighbourhood at 40 metre radius around the focal host
NemMeanBurden_40 Mean burden of H. polygyrus on the neighbourhood at 40 metre radius around the focal host
EimNoInf_40 Number of individuals infected with Eimeria on the neighbourhood at 40 metre radius around the focal host
EimNoUninf_40 Number of individuals not infected with Eimeria on the neighbourhood at 40 metre radius around the focal host
EimPrev_40 Prevalence of Eimeria on the neighbourhood at 40 metre radius around the focal host
EimNoTotal_40 Number of hosts in the neighbourhood with Eimeria at 40 metre radius around the focal host
PropOnGrid_50 Proportion of the neighbourhood on the grid at 50 metre radius around the focal host
NemNoInf_50 Number of individuals infected with H. polygyrus on the neighbourhood at 50 metre radius around the focal host
NemNoUninf_50 Number of individuals not infected with H. polygyrus on the neighbourhood at 50 metre radius around the focal host
NemPrev_50 Prevalence of H. polygyrus on the neighbourhood at 50 metre radius around the focal host
NemNoTotal_50 Number of hosts in the neighbourhood with H. polygyrus at 50 metre radius around the focal host
NemTotBurden_50 Total burden of H. polygyrus on the neighbourhood at 50 metre radius around the focal host
NemMeanBurden_50 Mean burden of H. polygyrus on the neighbourhood at 50 metre radius around the focal host
EimNoInf_50 Number of individuals infected with Eimeria on the neighbourhood at 50 metre radius around the focal host
EimNoUninf_50 Number of individuals not infected with Eimeria on the neighbourhood at 50 metre radius around the focal host
EimPrev_50 Prevalence of Eimeria on the neighbourhood at 50 metre radius around the focal host
EimNoTotal_50 Number of hosts in the neighbourhood with Eimeria at 50 metre radius around the focal host

Output Data Structure - statistical model output files

These files are titled:

STATS - Eapp INF NHMeanburden 17.csv, STATS - Eapp INF NHMeanburden 34.csv, STATS - Eapp INF NHMeanburden 51.csv, STATS - Eapp INF NHMeanburden all.csv, STATS - Eapp INF NHprev 17.csv, STATS - Eapp INF NHprev 34.csv, STATS - Eapp INF NHprev 51.csv, STATS - Eapp INF NHprev all.csv, STATS - Eapp Int NHMeanburden 17.csv, STATS - Eapp Int NHMeanburden 34.csv, STATS - Eapp Int NHMeanburden 51.csv, STATS - Eapp Int NHMeanburden all.csv, STATS - Eapp Int NHprev 17.csv, STATS - Eapp Int NHprev 34.csv, STATS - Eapp Int NHprev 51.csv, STATS - Eapp Int NHprev all.csv, STATS - Ehung INF NHMeanburden 17.csv, STATS - Ehung INF NHMeanburden 34.csv, STATS - Ehung INF NHMeanburden 51.csv, STATS - Ehung INF NHMeanburden all.csv, STATS - Ehung INF NHprev 17.csv, STATS - Ehung INF NHprev 34.csv, STATS - Ehung INF NHprev 51.csv, STATS - Ehung INF NHprev all.csv, STATS - Ehung Int NHMeanburden 17.csv, STATS - Ehung Int NHMeanburden 34.csv, STATS - Ehung Int NHMeanburden 51.csv, STATS - Ehung Int NHMeanburden all.csv, STATS - Ehung Int NHprev 17.csv, STATS - Ehung Int NHprev 34.csv, STATS - Ehung Int NHprev 51.csv, STATS - Ehung Int NHprev all.csv

Which contain the statistical outputs of the models run with the file run.statistical.analysis.R. These files contain the following columns.

Term Description
dist Neighbourhood radius around the focal host (metres)
estimates Model estimate of the primary predictor variable
lowerCI Lower 95% credible interval of estimate of the primary predictor variable
upperCI Upper 95% credible interval of estimate of the primary predictor variable
estimates.tothosts Model estimate of the predictor variable total number of hosts
lowerCI.tothosts Lower 95% credible interval of estimate of the predictor variable total number of hosts
upperCI.tothosts Upper 95% credible interval of estimate of the predictor variable total number of hosts
estimates.EimNHprev Model estimate of the predictor variable Eimeria prevalence in the neighbourhood
lowerCI.EimNHprev Lower 95% credible interval of estimate of the predictor variable Eimeria prevalence in the neighbourhood
upperCI.EimNHprev Upper 95% credible interval of estimate of the predictor variable Eimeria prevalence in the neighbourhood
estimates.HpolINF Model estimate of the predictor variable H. polygyrus infection status of the focal host
lowerCI.HpolINF Lower 95% credible interval of estimate of the predictor variable H. polygyrus infection status of the focal host
upperCI.HpolINF Upper 95% credible interval of estimate of the predictor variable H. polygyrus infection status of the focal host
estimates.Sex Model estimate of the predictor variable focal host Sex
lowerCI.Sex Lower 95% credible interval of estimate of the predictor variable focal host Sex
upperCI.Sex Upper 95% credible interval of estimate of the predictor variable focal host Sex
estimates.Age Model estimate of the predictor variable focal host Age
lowerCI.Age Lower 95% credible interval of estimate of the predictor variable focal host Age
upperCI.Age Upper 95% credible interval of estimate of the predictor variable focal host Age
estimates.capdate1 Model estimate of the predictor variable capture date*
lowerCI.capdate1 Lower 95% credible interval of estimate of the predictor variable capture date*
upperCI.capdate1 Upper 95% credible interval of estimate of the predictor variable capture date*
estimates.capdate2 Model estimate of the predictor variable capture date*
lowerCI.capdate2 Lower 95% credible interval of estimate of the predictor variable capture date*
upperCI.capdate2 Upper 95% credible interval of estimate of the predictor variable capture date*
estimates.intercept Model estimate of the model intercept
lowerCI.intercept Lower 95% credible interval of estimate of the model intercept
upperCI.intercept Upper 95% credible interval of estimate of the model intercept
estimates.raneff Model estimate of the random effect
lowerCI.raneff Lower 95% credible interval of estimate of the random effect
upperCI.raneff Upper 95% credible interval of estimate of the random effect

*Capture date is a second-order polynomial variable which is why there are two estimates for this.

Instructions for use ?‍?

There are three ways to recreate the figures in the paper:

  1. from scratch, generating the neighbourhood data files (step #1 below), followed by running the statistical analysis code (step #2) and the plotting code to generate the figures (step #3);
  2. use the previously-generated neighbourhood data files (“DATA -…csv”) and just run the statistical analysis code (step #2) and the plotting code to generate the figures (step #3);
  3. use the previously-generated statistical output files (“STATS - …csv”) and just run the plotting code to generate the figures (step #3).

Step 1: Open file execute.parasite.function.R. This file takes raw data (described below) and generates neighbourhood data files that includes information on number of neighbours, and their infection statuses, for each focal capture in the raw data set. These neighbourhood data files ("DATA - …csv") are then used for the statistical analyses in step #2 below.

Lines 6 - 22 clears the environment and loads the required data file ("raw data.csv"), helper function files (exppoints.R, make.dist.vector.R, prop.on.grid.R) and package (gtools).

Lines 26 - 37 sets up distance matrices and calculates the range of distances to be used as neighbourhood sizes.

Lines 41 - 61 defines the neighbour and focal variables to be used and then prepares the dataframes accordingly.

Lines 65 - 94 defines column names for the output dataframes.

Lines 98 - 106 runs the parasite function across the selected temporal ranges.

Lines 110 - 119 write output files for these runs ("DATA - …csv").

Step 2: Open file run.statistical.analysis.R. This file runs Bayesian Generalised Linear Mixed Effects Models on the data generated by the file above to determine the effect of neighbour parasites on focal parasites at increasing spatial scales and specified time windows. Outputs are stored in csv files ("STATS - …csv"`) used to generate the plots in step #3 below.

Line 8 clears the environment.

Line 12 - 22 loads the data output from the neighbourhood analysis generated in the execute.parasite.function.R file ("DATA - …csv").

Line 26 - 28 loads the required helper function file (model.run.R) and statistical package (brms).

Line 33 sets the labels to be used which is a list of the distances which have been selected.

Lines 42 - 60 selects response and explanatory parasites and variable names.

Lines 65 - 85 runs the appropriate suite of models.

Lines 90 - 136 saves the output files for the models that have been run ("STATS - …csv").

Step 3: Open file combined.plotting.code.R. This file generates multipanel plots showing H. polygyrus neighbourhood effects on both E. hungaryensis (left-hand column) and E. apionodes (right-hand column) focal infection status (y-axis) against neighbourhood size (x-axis) for the different time windows (panels). Uses statistical output files (“STATS - …csv”) generated from Step 2.

Line 8 clears the environment.

Lines 12 - 58 loads the appropriate statistical output files generated in the run.statistical.analysis.R file (“STATS - …csv”).

Lines 64 – 73 creates functions to colour code points, depending whether the 95% CIs cross zero.

Line 78 sets the labels to be used which is a list of the distances which have been selected.

Lines 83 – 84 generate the output pdf with an appropriate name.

Lines 91- 94 sets plotting parameters (layout, margins etc).

Lines 97 – 162 creates a function (plotfunc) for creating the paired E. hungaryensis and E. apionodes plots for each time window in turn.

Lines 166 – 170 calls plotfunc for each time window in turn.

Lines 174 - 189 adds a single x-axis label for the whole plot and species labels for the two columns.

Lines 193 – 198 adds an appropriate single y-axis label, depending on the neighbourhood and focal variables.

Line 200 closes the pdf.

Funding

Natural Environment Research Council, Award: NE/I024038/1

Natural Environment Research Council, Award: NE/I026367/1

Wellcome Trust, Award: 095831