Kristan Schneider How often are you hit by an infection ...

Post on 15-Feb-2022

4 views 0 download

Transcript of Kristan Schneider How often are you hit by an infection ...

KristanSchneider

Howoftenareyouhitbyaninfection?-Alikelihood

approachtodeterminethemultiplicityofinfection

ROeS2013,Sept.12,2013

Whatismalaria?

•Infectiousdiseasecausedbyparasites(genus

Pla

sm

od

ium;eukaryote)

•40%oftheworld’spopulationatmalariarisk

•Worldwide200-300millioninfections&1-3milliondeathsperyear

•Enormouseconomicdamageeveryyear

Transmissioncycle

Transmissioncycle

Transmissioncycle

Malariacontrol

•Goalofmalariacontrol:

◦reducedeceaseburden⇒drugtreatments

Malariacontrol

•Goalofmalariacontrol:

◦reducedeceaseburden⇒drugtreatments

◦reducetransmission⇒bednets,vectorcontrol,...

Malariacontrol

•Goalofmalariacontrol:

◦reducedeceaseburden⇒drugtreatments

◦reducetransmission⇒bednets,vectorcontrol,...

Q:Howtomeasureefficiencyofcontrolinterventions?

Malariacontrol

•Goalofmalariacontrol:

◦reducedeceaseburden⇒drugtreatments

◦reducetransmission⇒bednets,vectorcontrol,...

Q:Howtomeasureefficiencyofcontrolinterventions?

A:Multiplicityofinfection=metricfortransmissionintensity

Malariacontrol

•Goalofmalariacontrol:

◦reducedeceaseburden⇒drugtreatments

◦reducetransmission⇒bednets,vectorcontrol,...

Q:Howtomeasureefficiencyofcontrolinterventions?

A:Multiplicityofinfection=metricfortransmissionintensity

→co-infectionsmightincreasediseaseseverity

Malariacontrol

•Goalofmalariacontrol:

◦reducedeceaseburden⇒drugtreatments

◦reducetransmission⇒bednets,vectorcontrol,...

Q:Howtomeasureefficiencyofcontrolinterventions?

A:Multiplicityofinfection=metricfortransmissionintensity

→co-infectionsmightincreasediseaseseverity

→metrictransmissionintensity

Malariacontrol

•Goalofmalariacontrol:

◦reducedeceaseburden⇒drugtreatments

◦reducetransmission⇒bednets,vectorcontrol,...

Q:Howtomeasureefficiencyofcontrolinterventions?

A:Multiplicityofinfection=metricfortransmissionintensity

→co-infectionsmightincreasediseaseseverity

→metrictransmissionintensity

→impactstatisticsbasedongeneticdata

Malariacontrol

•Goalofmalariacontrol:

◦reducedeceaseburden⇒drugtreatments

◦reducetransmission⇒bednets,vectorcontrol,...

Q:Howtomeasureefficiencyofcontrolinterventions?

A:Multiplicityofinfection=metricfortransmissionintensity

→co-infectionsmightincreasediseaseseverity

→metrictransmissionintensity

→impactstatisticsbasedongeneticdata

Multiplicityofinfection-Whyisitimportant?

Multiplicityofinfection-Whyisitimportant?

Multiplicityofinfection-Whyisitimportant?

Multiplicityofinfection-Whyisitimportant?

Multiplicityofinfection-Whyisitimportant?

Multiplicityofinfection-Whyisitimportant?

Multiplicityofinfection-Whyisitimportant?

Multiplicityofinfection-Whyisitimportant?

Multiplicityofinfection-Whyisitimportant?

Multiplicityofinfection-Whyisitimportant?

•Largenumberofco-infections=hightransmission

Multiplicityofinfection-Whyisitimportant?

•Largenumberofco-infections=hightransmission

•Hightransmission=moregeneticvariation

→Multiplicityofinfection=keyquantityingeneticstudies

Approach

Approach

Approach

•Nbloodsamples

Approach

•Nbloodsamples

•nstrains(versionsofageneticmarkers)

Approach

•Nbloodsamples

•nstrains(versionsofageneticmarkers)

•n ii iobservednumbersampleswithconfigurationii i(0-1vector;lengthn)

Approach

•Nbloodsamples

•nstrains(versionsofageneticmarkers)

•n ii iobservednumbersampleswithconfigurationii i(0-1vector;lengthn)

•Qii iexpectedfrequencysampleswithconfigurationii i

Approach

•Nbloodsamples

•nstrains(versionsofageneticmarkers)

•n ii iobservednumbersampleswithconfigurationii i(0-1vector;lengthn)

•Qii iexpectedfrequencysampleswithconfigurationii i

Likelihood:

ii i

Qn ii iii i

Log-likelihood:

L=

ii i

n ii ilogQii i

HowtoderiveQii i?

•Assumptions:

HowtoderiveQii i?

•Assumptions:

◦pp p=(p1,...,pn)...frequencyvectorofstrain

HowtoderiveQii i?

•Assumptions:

◦pp p=(p1,...,pn)...frequencyvectorofstrain

◦Infectionsrare&independentevents

HowtoderiveQii i?

•Assumptions:

◦pp p=(p1,...,pn)...frequencyvectorofstrain

◦Infectionsrare&independentevents

•Implications:

◦Numberofinfectingstrains∼positivePoissondistribution(parameterλ)

HowtoderiveQii i?

•Assumptions:

◦pp p=(p1,...,pn)...frequencyvectorofstrain

◦Infectionsrare&independentevents

•Implications:

◦Numberofinfectingstrains∼positivePoissondistribution(parameterλ)

P(X=m)=

1eλ−1λm

m!

m>1

HowtoderiveQii i?

•Assumptions:

◦pp p=(p1,...,pn)...frequencyvectorofstrain

◦Infectionsrare&independentevents

•Implications:

◦Numberofinfectingstrains∼positivePoissondistribution(parameterλ)

P(X=m)=

1eλ−1λm

m!

m>1

◦InfectionconditionedonX=mstrainsmultinomiallydistributed∼Mult(m,pp p)

HowtoderiveQii i?

•Assumptions:

◦pp p=(p1,...,pn)...frequencyvectorofstrain

◦Infectionsrare&independentevents

•Implications:

◦Numberofinfectingstrains∼positivePoissondistribution(parameterλ)

P(X=m)=

1eλ−1λm

m!

m>1

◦InfectionconditionedonX=mstrainsmultinomiallydistributed∼Mult(m,pp p)

◦Quantityofinterest=

λ1−e−λ(meanofpositivePoissondistr.)

HowtoderiveQii i?

•Assumptions:

◦pp p=(p1,...,pn)...frequencyvectorofstrain

◦Infectionsrare&independentevents

•Implications:

◦Numberofinfectingstrains∼positivePoissondistribution(parameterλ)

P(X=m)=

1eλ−1λm

m!

m>1

◦InfectionconditionedonX=mstrainsmultinomiallydistributed∼Mult(m,pp p)

◦Quantityofinterest=

λ1−e−λ(meanofpositivePoissondistr.)

◦Likelihood:

L=L(λ,pp p)=−Nlog(eλ−1)+

n∑ k=1

Nklog(eλpk−1)

◦Nk...numberofsampleswithstraink

Results •Aims:

Results •Aims:

◦MLestimateofparametersθ̂θ θ=(λ̂,p̂p p)?

Results •Aims:

◦MLestimateofparametersθ̂θ θ=(λ̂,p̂p p)?

→multidimensionalNewtonmethod(nindependentparameters)

Results •Aims:

◦MLestimateofparametersθ̂θ θ=(λ̂,p̂p p)?

→multidimensionalNewtonmethod(nindependentparameters)

◦Existence,uniqueness,numericaleffort?

Results •Aims:

◦MLestimateofparametersθ̂θ θ=(λ̂,p̂p p)?

→multidimensionalNewtonmethod(nindependentparameters)

◦Existence,uniqueness,numericaleffort?

•Results:

◦θ̂θ θ=(λ̂,p̂p p)existsandisunique

Results •Aims:

◦MLestimateofparametersθ̂θ θ=(λ̂,p̂p p)?

→multidimensionalNewtonmethod(nindependentparameters)

◦Existence,uniqueness,numericaleffort?

•Results:

◦θ̂θ θ=(λ̂,p̂p p)existsandisunique

◦Eθ̂θ θNk=Nkexpected=observednumberofsamplescontainingstraink

Results •Aims:

◦MLestimateofparametersθ̂θ θ=(λ̂,p̂p p)?

→multidimensionalNewtonmethod(nindependentparameters)

◦Existence,uniqueness,numericaleffort?

•Results:

◦θ̂θ θ=(λ̂,p̂p p)existsandisunique

◦Eθ̂θ θNk=Nkexpected=observednumberofsamplescontainingstraink

◦λ̂foundbyiterating

λt+1=λt−

λt+

n∑ k=1

log(

1−NkN(1−e−λt))

1−

n∑ k=1

Nk

Neλt−Nk(e−λt−1)

,

convergesfromallstartingvaluesλ0>λ̂

Results •Aims:

◦MLestimateofparametersθ̂θ θ=(λ̂,p̂p p)?

→multidimensionalNewtonmethod(nindependentparameters)

◦Existence,uniqueness,numericaleffort?

•Results:

◦θ̂θ θ=(λ̂,p̂p p)existsandisunique

◦Eθ̂θ θNk=Nkexpected=observednumberofsamplescontainingstraink

◦λ̂foundbyiterating

λt+1=λt−

λt+

n∑ k=1

log(

1−NkN(1−e−λt))

1−

n∑ k=1

Nk

Neλt−Nk(e−λt−1)

,

convergesfromallstartingvaluesλ0>λ̂

◦p̂k=−1 λ̂log(

1−NkN(1−e−λ̂))

.

Results

Results

•Cameroon

Results

•Cameroon

•331bloodsample

Results

•Cameroon

•331bloodsample

Results

•Cameroon

•331bloodsample

Results

•Cameroon

•331bloodsample

Results

•Cameroon

•331bloodsample

Results

•Cameroon

•331bloodsample

•8microsatellitemarkers

Results

•Cameroon

•331bloodsample

•8microsatellitemarkers

æ

ææ

ææ

ææ

æ

302kb313kb319kb379kb335kb363kb383kb429kb

1.

1.1

1.2

1.3

1.4

1.5

microsatellitelocus

ΛeΛ

eΛ-1

Results •Aims:

◦Confidenceintervalls

Results •Aims:

◦Confidenceintervalls

◦Testingtheestimates

Results •Aims:

◦Confidenceintervalls

◦Testingtheestimates

•Approach:ProfileLikelihood

◦λfixedL(λ,pp p)→max?

Results •Aims:

◦Confidenceintervalls

◦Testingtheestimates

•Approach:ProfileLikelihood

◦λfixedL(λ,pp p)→max?

◦2(maxλ,pp pL(λ,pp p)

︸︷︷

︸max.LH

−max pp pL(λ0,pp p)

︸︷︷

︸profileLH

)∼χ2 1

Results •Aims:

◦Confidenceintervalls

◦Testingtheestimates

•Approach:ProfileLikelihood

◦λfixedL(λ,pp p)→max?

◦2(maxλ,pp pL(λ,pp p)

︸︷︷

︸max.LH

−max pp pL(λ0,pp p)

︸︷︷

︸profileLH

)∼χ2 1

◦Findλ,λwith:max pp pL(λ,pp p)=max pp pL(λ,pp p)=maxλ,pp pL(λ,pp p)−χ2 1(1−α)/2=ℓ∗

Results •Aims:

◦Confidenceintervalls

◦Testingtheestimates

•Approach:ProfileLikelihood

◦λfixedL(λ,pp p)→max?

◦2(maxλ,pp pL(λ,pp p)

︸︷︷

︸max.LH

−max pp pL(λ0,pp p)

︸︷︷

︸profileLH

)∼χ2 1

◦Findλ,λwith:max pp pL(λ,pp p)=max pp pL(λ,pp p)=maxλ,pp pL(λ,pp p)−χ2 1(1−α)/2=ℓ∗

◦Trick:maximizeconditionedonL(λ,pp p)=ℓ∗

→Lagrangemultiplies&(n+1)-dimensionalNewtonmethod

Results

Results:

◦1−αconfidenceintervalsexist&uniquelydefined

Results

Results:

◦1−αconfidenceintervalsexist&uniquelydefined

◦Boundsfoundbyiterating2-dimrecursion

Results

Results:

◦1−αconfidenceintervalsexist&uniquelydefined

◦Boundsfoundbyiterating2-dimrecursion

◦Approachconverges(locally)quadratically

Results

Results:

◦1−αconfidenceintervalsexist&uniquelydefined

◦Boundsfoundbyiterating2-dimrecursion

◦Approachconverges(locally)quadratically

◦TestforH0:λ=λ0vs.HA:λ6=λ0

rejectH0ifλ06∈[λ,λ]

p-value:

χ2 1

(

2(maxλ,pp pL(λ,pp p)−max pp pL(λ0,pp p)))

Results

Results:

◦1−αconfidenceintervalsexist&uniquelydefined

◦Boundsfoundbyiterating2-dimrecursion

◦Approachconverges(locally)quadratically

◦TestforH0:λ=λ0vs.HA:λ6=λ0

rejectH0ifλ06∈[λ,λ]

p-value:

χ2 1

(

2(maxλ,pp pL(λ,pp p)−max pp pL(λ0,pp p)))

æ

ææ

ææ

ææ

æ

æ

ææ

ææ

ææ

æ

æ

ææ

ææ

ææ

æ

302kb313kb319kb379kb335kb363kb383kb429kb

1.

1.1

1.2

1.3

1.4

1.5

microsatellitelocus

ΛeΛ

eΛ-1

Results

Results:

◦1−αconfidenceintervalsexist&uniquelydefined

◦Boundsfoundbyiterating2-dimrecursion

◦Approachconverges(locally)quadratically

◦TestforH0:λ=λ0vs.HA:λ6=λ0

rejectH0ifλ06∈[λ,λ]

p-value:

χ2 1

(

2(maxλ,pp pL(λ,pp p)−max pp pL(λ0,pp p)))

æ

ææ

ææ

ææ

æ

æ

ææ

ææ

ææ

æ

æ

ææ

ææ

ææ

æ

302kb313kb319kb379kb335kb363kb383kb429kb

1.

1.1

1.2

1.3

1.4

1.5

microsatellitelocus

ΛeΛ

eΛ-1

302kb313kb 319kb379kb335kb363kb 383kb429kb

302kb

313kb

319kb

379kb

335kb

363kb

383kb

429kb

Results (θ̂θ θ−θθ θ0)∼N(00 0,I−1N(θθ θ0))

æ

ææ

ææ

ææ

æ

æ

ææ

ææ

ææ

æ

æ

ææ

ææ

ææ

æ

æ

ææ

ææ

ææ

æ

æ

ææ

ææ

ææ

æ

æ

ææ

ææ

ææ

æ

302kb

313kb

319kb

379kb

335kb

363kb

383kb

429kb

1.

1.1

1.2

1.3

1.4

1.5

microsatellitelocus

302kb313kb 319kb379kb335kb363kb 383kb429kb

302kb

313kb

319kb

379kb

335kb

363kb

383kb

429kb

302kb313kb 319kb379kb335kb363kb 383kb429kb

302kb

313kb

319kb

379kb

335kb

363kb

383kb

429kb

Results

ææ

æ

ææ

ææ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

ææ

æ

ææ

æ

ææ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

fr13

c4

b3

ps6

ps7

k6

l1u5

1.

1.1

1.2

microsatellitelocus

æ

æ

æ

ææ

ææ

æ

æ

æ

æ

ææ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

ææ

ææ

æ

æ

æ

æ

ææ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

U7

L5

J3

J6

U6

L4

U5

K6

0.91.

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

microsatellitelocus

Venezuela

Kenya

Results

ææ

æ

ææ

ææ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

ææ

æ

ææ

æ

ææ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

fr13

c4

b3

ps6

ps7

k6

l1u5

1.

1.1

1.2

microsatellitelocus

æ

æ

æ

ææ

ææ

æ

æ

æ

æ

ææ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

ææ

ææ

æ

æ

æ

æ

ææ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

æ

U7

L5

J3

J6

U6

L4

U5

K6

0.91.

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

microsatellitelocus

Venezuela

Kenya

æ

æ

æ

æ

æ

æ

æ

æ

æ

Kenya

Cameroon

Venezuela

1.

1.1

1.2

1.3

1.4

1.5

mean±sd

Conclusions

•MLestimatefornumberofco-infections

(keyparameterinmalaria)

Conclusions

•MLestimatefornumberofco-infections

(keyparameterinmalaria)

•ML-approachworkswell

Conclusions

•MLestimatefornumberofco-infections

(keyparameterinmalaria)

•ML-approachworkswell

•Robustnessstudy→futurework

Conclusions

•MLestimatefornumberofco-infections

(keyparameterinmalaria)

•ML-approachworkswell

•Robustnessstudy→futurework

•Includingseveralmarkersatthesametime

Conclusions

•MLestimatefornumberofco-infections

(keyparameterinmalaria)

•ML-approachworkswell

•Robustnessstudy→futurework

•Includingseveralmarkersatthesametime

McCollumetal,2012

MalariaJ

Schneider&Kim,2010,

Theo.Pop.Biol.

Conclusions

•MLestimatefornumberofco-infections

(keyparameterinmalaria)

•ML-approachworkswell

•Robustnessstudy→futurework

•Includingseveralmarkersatthesametime

McCollumetal,2012

MalariaJ

Schneider&Kim,2010,

Theo.Pop.Biol.