Wh acquires
Who
i
iinfection
f ti from
f
whom:
h
Household
H
h ld transmission
t
i i off respiratory
i t
syncytial virus (RSV)
Munywoki PK1*, Koech DC1, Kibirige,
Kibirige NA1, Cane PA2, Medley GF3, Nokes DJ1,, 3
1 Kenya Medical Research Institute, Kenya; 2 Health Protection Agency, UK ; 3 University of Warwick, UK
* pmunywoki@kilifi.kemri-wellcome.org
Background
Methodology
¾RSV is a major cause of childhood ARI worldwide. In
Kilifi around 1-2 in every 100 infants are admitted with
severe RSV disease
di
per year
Fig.
g 1: WAIFW Matrix
infected
¾ Currently no licensed RSV vaccines exists =>
immunological immaturity and maternal antibodies are the
major obstacles =>
> for vaccine targeting 11-3yr
3yr age group
group.
infant
susceptible
older
ld
¾Need to carefully evaluate alternative approaches, such as
targeting older infants, household siblings, school children
or mothers.
mothers
Distribution of study
y HHs
¾Potential impact of such strategies will be intimately
linked to WAIFW (Who Acquires Infection From Whom):
which groups are most important in infecting the infant.
infant
A schema of the prospective household study
Obj ti
Objectives
St d IImplementation
Study
l
t ti
¾Determine the proportion of primary infant infections that
arise
i ffrom elder
ld siblings
ibli
or from
f
the
h mother
h
¾ Sensitization & HH recruitment prior to
epidemic
id i – Oct
O t+N
Nov 2009
¾Estimate the household ((HH)) reproductive
p
potential
p
of
RSV and risk of transmission per contact
¾ Eligible HHs had an infant plus ≥1older siblings
¾Quantify rates of infection and recovery of RSV and other
respiratory viruses (RV) in the HH; stratify for age i.e.
infants, older children & adults
¾Evaluate the diagnostic performance of oral fluid (OF) in
detecting infection using RT-PCR methods
¾ Follow
F ll up for
f 6 months,
th one full
f ll RSV epidemic
id i
¾ Surveillance methods for RV infection
• Home visits: Nasopharyngeal flocked swab
(NFS) and illness assessment twice
twice-a-week
a week +
OF collection once
once-a-week.
a week.
• Clinic visits: For clinical assessment and
treatment. Samples only collected if due
Fig 2: Matsangoni map showing distribution of the recruited
Fig.
households (navy blue). Insert (Kilifi Epi-DSS map)
R l
Results
3. Households retention
6. Prevalence of viruses in AR1 vs. non-ARI
Relation to index child
(n=534)
Live in same house (n=533)
Sleep
p in same room ((n=530))
Sleep same bed (n=530)
2. Summary data
¾ 60 households recruited ggivingg a total of 596 individuals
¾ 13 (22%) households lost to follow up
¾ Total of 19,816
19 816 home visits resulting in 16,284
16 284 NFS and
9,226 OF beingg taken => from 554 participants
p
p
¾ In 3,624
3,6 visits
v s ts the
t e participants
pa t c pa ts had
ad symptoms
sy pto s of
o acute
respiratory infection (ARI)
% Virus possitive
40
300
20
2
10
0
ARI (N=572)
20
Non-ARI (N=446)
10
01 Jan
01 Feb
01 Mar
01 Apr
01 May
Rhi
Rhino
RSV Adeno
Ad
C
Corona
PIV
01 Jun
Date
Fig.
g 3: HH retention over the follow
f
up
p pperiod
B1
S
Inf
Inf
M
A
M
Jun'10
Dec'09
J
F
M
A
M
Jun'10
Apr'09 Jun
B2 Mum
Aug
Oct
Dec Feb'10
Birth date
A
M
Jun'10
Number of
NFS (%)
OF (%)
ARI (%)
56
2052
1767 (89.7)
980 (99.4) 842 (42.7)
Brother
96
3389
3035 (89.6)
(89 6)
1657 (97
(97.8)
8) 884 (26.1)
(26 1)
Sister
88
3229
2859 (88.5)
1594 (98.7) 727 (22.5)
Mother
65
2307
1967 (85.3)
1117 (96.8)
139 (6.0)
Father
41
1346
904 (67
(67.1)
1)
545 (81.0)
(81 0)
54 (4.0)
(4 0)
Cousin
106
4092
3353 (81.9)
1911 (93.4) 696 (17.0)
Uncle/aunt
70
2579
1694 (66.3)
1020 (79.8) 226 (8.9)
Others
32
928
705 (76.0)
402 (86.6)
554
19,816
16,284 (82)
B1
10
S
8
Coronavirus (OC43)
Inf
6
Adeno
B1
4
Self
Total
F
S
2
Age in Months
5. Home visits, NFS, OF and ARI by
y relation
Index child Participants Home visits
Rhino
2
1
0
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
index child was the youngest child in the HH at recruitment.
Relation to
J
Inf
Age in years
0
0
0 10 20 30 40 50 60 70 80 90 100
B2 Mum
B1
4
3
S
4
3
1
10
10 15 20 25 30 35 40
Household sizes
Dec'09
2
No. of index childreen
50
0
40
30
20
2
No. of paarticipannts
N
8
6
4
5
RSV A
5
(c)
5
60
(d)
6
(b)
6
70
10
4 HH sizes and age at enrollment
4.
(a)
FLU hMPV
7. Infection patterns within one HH
B2 Mum
01 Dec
B2 Mum
01 Nov
0
Fig. 5: Prevalence
of the identified
respiratory viruses
in the ARI cases
relative to non-ARI
in randomly
selected samples
0
0
Education (n=592)
30
No. of hoousehold
N
ds
Sex (n=558)
Occupation (n=596)
Frequency (%)
444 (74.5)
76 (12.6)
(
)
44 (7.4)
30 (5.0)
1 (0.2)
1 (0.2)
(0 2)
70 (11.8)
101 (17.1)
(17 1)
107 (18.1)
140 (23.7)
72 (12.2)
(
)
53 (9.0)
48 (8.1)
262 (47.0)
274 (46.0)
(46 0)
187 (31.4)
70 (11.7)
(11 7)
65 (10.9)
269 (45.4)
68 (11.5)
(
)
100 (16.9)
140 (23.7)
(23 7)
15 (2.5)
198 (37.1)
(37 1)
115 (21.5)
107 (20.0)
(20 0)
114 (21.3)
293 (55.0)
201 ((37.9))
134 (25.3)
2
Age groups (n=591)
Description
Nov ’09
Dec
Jan
Feb
Apr
Jun’10
Jun
10
Under 1
1 to
t 4
5 to 9
10 to 19
20 to 29
30 to 39
Above 40
Male
Unemployed
Pupils
F
Farmers
Employed
None
Nurseryy
Class 1 to 3
Class 4 to 8
Secondary
Siblings
Parents
C i
Cousin
Others
as index child
as index child
as index child
0
Characteristic
Month of consent (n=596)
No. of Housseholds
50
1. Baseline characteristics of the cohort
Dec'09
J
F
M
A
Date
M
Jun'10
Dec'09
J
F
M
Date
Fig. 6: Infection
ppatterns off RSV A,,
Rhinovirus,
Adenovirus and
Coronavirus OC43
within a household of
5 members ; infant (1
month), sister (2yrs),
b th 1 (6 yrs),
brother
)
brother 2 (9 yrs) and
mother (29 yrs) at
start of sampling on
21/12/2009) . First
HH with complete
viral screen
Conclusion
¾ Early results are encouraging that methods will
yyield data to explore
p
the studyy objectives
j
¾Rhinovirus, RSV
¾Rhinovirus
RSV, adenovirus and corona virus
(OC43) are the most prevalent viruses in the
cohort
¾These viruses could help in elucidating
transmission events within households
56 (6.0)
9,226 (93) 3,624 (18)
Table: Frequency distribution of home visits, NFS, OF and ARI over the study
period by relation to the index child.
Support: Wellcome Trust
084633)
((ref
e 08
633)