Wh i i f ti f h H h ld t i i f i tWho acquires infection from whom: Household transmission of respiratory syncytial virus (RSV)syncytial virus (RSV)

Munywoki PK1* Koech DC1 Kibirige NA1 Cane PA2 Medley GF3 Nokes DJ1, 3Munywoki PK , Koech DC , Kibirige, NA , Cane PA , Medley GF , Nokes DJ ,

1 Kenya Medical Research Institute, Kenya; 2 Health Protection Agency, UK ; 3 University of Warwick, UK* pmunywoki@kilifi.kemri-wellcome.org

MethodologyBackgroundFig. 1: WAIFW MatrixRSV is a major cause of childhood ARI worldwide. In

infected

gKilifi around 1-2 in every 100 infants are admitted with

RSV disevere RSV disease per year

infantCurrently no licensed RSV vaccines exists => susceptible

infant

ld

immunological immaturity and maternal antibodies are the major obstacles > for vaccine targeting 1 3yr age group oldermajor obstacles => for vaccine targeting 1-3yr age group.

Need to carefully evaluate alternative approaches, such as

Distribution of study HHstargeting older infants, household siblings, school children or mothers yor mothers.

Potential impact of such strategies will be intimately linked to WAIFW (Who Acquires Infection From Whom): which groups are most important in infecting the infant

A schema of the prospective household study

St d I l t tiObj tiwhich groups are most important in infecting the infant.

Study ImplementationObjectivesDetermine the proportion of primary infant infections that i f ld ibli f h h

Sensitization & HH recruitment prior to id i O t + N 2009arise from elder siblings or from the mother epidemic – Oct + Nov 2009

Estimate the household (HH) reproductive potential of Eligible HHs had an infant plus ≥1older siblings( ) p pRSV and risk of transmission per contact

F ll f 6 th f ll RSV id iQuantify rates of infection and recovery of RSV and other

Follow up for 6 months, one full RSV epidemic Quantify rates of infection and recovery of RSV and other

respiratory viruses (RV) in the HH; stratify for age i.e. Surveillance methods for RV infectioninfants, older children & adults • Home visits: Nasopharyngeal flocked swab

(NFS) and illness assessment twice a week +Evaluate the diagnostic performance of oral fluid (OF) in

(NFS) and illness assessment twice-a-week + OF collection once-a-week.Evaluate the diagnostic performance of oral fluid (OF) in

detecting infection using RT-PCR methodsOF collection once a week.

• Clinic visits: For clinical assessment and Fig 2: Matsangoni map showing distribution of the recruitedtreatment. Samples only collected if due

Fig. 2: Matsangoni map showing distribution of the recruited households (navy blue). Insert (Kilifi Epi-DSS map)

R lResults 3. Households retention1. Baseline characteristics of the cohort 6. Prevalence of viruses in AR1 vs. non-ARI

Characteristic Description Frequency (%) Fig. 5: Prevalence of the identified

50 30

Month of consent (n=596) Nov ’09Dec

444 (74.5)76 (12.6)

of the identified respiratory viruses in the ARI cases0

40se

hold

s

20sitiv

e ARI (N=572)

Jan Feb

( )44 (7.4)30 (5.0)

in the ARI cases relative to non-ARI in randomly20

30 o

f Hou

s

rus p

os Non-ARI (N=446)

FebApr

Jun’10

30 (5.0)1 (0.2)1 (0 2)

in randomly selected samples

102

No.

10

% V

i

Jun 10 1 (0.2)Age groups (n=591) Under 1

1 t 470 (11.8)

101 (17 1)

0

01 Nov 01 Dec 01 Jan 01 Feb 01 Mar 01 Apr 01 May 01 Jun

0Rhi RSV Ad C PIV FLU hMPV1 to 4

5 to 9 101 (17.1)107 (18.1)

01 Nov 01 Dec 01 Jan 01 Feb 01 Mar 01 Apr 01 May 01 JunDate

Fig. 3: HH retention over the follow up period

Rhino RSV Adeno Corona PIV FLU hMPV

4 HH sizes and age at enrollment10 to 1920 to 29

140 (23.7)72 (12.2)

g f p p7. Infection patterns within one HH

4. HH sizes and age at enrollment30 to 39

Above 40

( )53 (9.0)48 (8.1) 10 70 6 6

(a) (b) (c) (d)RSV A

Mum Rhino

Mum

Fig. 6: Infection patterns of RSV A, Above 40 48 (8.1)

Sex (n=558) Male 262 (47.0)Occupation (n=596) Unemployed 274 (46 0)

8ds

600nts

5

en

5

(a) (b) (c) (d)

B1

B2

B1

B2

p f ,Rhinovirus, Adenovirus and Occupation (n=596) Unemployed

PupilsF

274 (46.0)187 (31.4)70 (11 7)

6ou

seho

ld

4050

artic

ipan 4

3x ch

ildre

43 nf

S

nfS Coronavirus OC43

within a household of Farmers

Employed70 (11.7)65 (10.9)

4N

o. o

f ho

2030

No.

of p

a

23

. of i

nde

23 I

Dec'09 J F M A M Jun'10

I

Dec'09 J F M A M Jun'105 members ; infant (1 month), sister (2yrs), b th 1 (6 )Education (n=592) None

Nursery269 (45.4)68 (11.5)

2N 2

10N

1

No

1

Adeno

B2

Mum Coronavirus (OC43)

B2

Mum brother 1 (6 yrs),

brother 2 (9 yrs) and mother (29 yrs) aty

Class 1 to 3Class 4 to 8

( )100 (16.9)140 (23 7)

0

0 20 30 405 15 25 3510

Household sizes

0

0 20 40 60 80 10010 30 50 70 90

Age in years

0

0 2 4 6 8 10Age in Months

0

Apr'09 Jun Aug Oct Dec Feb'10

Birth date SB

1

SB

1 mother (29 yrs) at start of sampling on 21/12/2009) FirstClass 4 to 8

Secondary140 (23.7)

15 (2.5)Relation to index child Siblings 198 (37 1)

Fig. 4: (a) HH sizes and (b) age distribution of the cohort at recruitment. (c) Age and (d) birth dates of the index children. The red line indicates the median. The

Inf

Dec'09 J F M A M Jun'10

Inf

Dec'09 J F M A M Jun'10

21/12/2009) . First HH with complete viral screenRelation to index child

(n=534)Siblings Parents C i

198 (37.1)115 (21.5)107 (20 0)

index child was the youngest child in the HH at recruitment. Date Date

5. Home visits, NFS, OF and ARI by relation CousinOthers

107 (20.0)114 (21.3) Conclusiony

Live in same house (n=533) as index child 293 (55.0)Sleep in same room (n=530) as index child 201 (37.9) Early results are encouraging that methods willRelation to Number ofp ( ) ( )Sleep same bed (n=530) as index child 134 (25.3) Early results are encouraging that methods will

yield data to explore the study objectives Relation to

Index child

Number of

Participants Home visits NFS (%) OF (%) ARI (%)

2. Summary data y p y j

Rhinovirus RSV adenovirus and corona virusSelf 56 2052 1767 (89.7) 980 (99.4) 842 (42.7)

Brother 96 3389 3035 (89 6) 1657 (97 8) 884 (26 1)

60 households recruited giving a total of 596 individualsRhinovirus, RSV, adenovirus and corona virus

(OC43) are the most prevalent viruses in the Brother 96 3389 3035 (89.6) 1657 (97.8) 884 (26.1)

Sister 88 3229 2859 (88.5) 1594 (98.7) 727 (22.5)g g

13 (22%) households lost to follow upcohortMother 65 2307 1967 (85.3) 1117 (96.8) 139 (6.0)

Father 41 1346 904 (67 1) 545 (81 0) 54 (4 0)13 (22%) households lost to follow up

Total of 19 816 home visits resulting in 16 284 NFS andThese viruses could help in elucidating

Father 41 1346 904 (67.1) 545 (81.0) 54 (4.0)

Cousin 106 4092 3353 (81.9) 1911 (93.4) 696 (17.0)Total of 19,816 home visits resulting in 16,284 NFS and

9,226 OF being taken => from 554 participantstransmission events within householdsUncle/aunt 70 2579 1694 (66.3) 1020 (79.8) 226 (8.9)

Others 32 928 705 (76.0) 402 (86.6) 56 (6.0)g p p

In 3,624 visits the participants had symptoms of acute Support: Wellcome TrustOthers 32 928 705 (76.0) 402 (86.6) 56 (6.0)

Total 554 19,816 16,284 (82) 9,226 (93) 3,624 (18)3,6 v s ts t e pa t c pa ts ad sy pto s o acuterespiratory infection (ARI)

Support: Wellcome Trust (ref 084633)Table: Frequency distribution of home visits, NFS, OF and ARI over the study

period by relation to the index child. ( e 08 633)period by relation to the index child.