Impact of Intensive Handwashing Promotion on Secondary Household Influenza-Like Illness in Rural Bangladesh: Findings from a Randomized Controlled Trial

<div><p>Rationale</p><p>There is little evidence for the efficacy of handwashing for prevention of influenza transmission in resource-poor settings. We tested the impact of intensive handwashing promotion on household transmission of influenza-like illness and influenza in rural Bangladesh.</p><p>Methods</p><p>In 2009–10, we identified index case-patients with influenza-like illness (fever with cough or sore throat) who were the only symptomatic person in their household. Household compounds of index case-patients were randomized to control or intervention (soap and daily handwashing promotion). We conducted daily surveillance and collected oropharyngeal specimens. Secondary attack ratios (SAR) were calculated for influenza and ILI in each arm. Among controls, we investigated individual risk factors for ILI among household contacts of index case-patients.</p><p>Results</p><p>Among 377 index case-patients, the mean number of days between fever onset and study enrollment was 2.1 (SD 1.7) among the 184 controls and 2.6 (SD 2.9) among 193 intervention case-patients. Influenza infection was confirmed in 20% of controls and 12% of intervention index case-patients. The SAR for influenza-like illness among household contacts was 9.5% among intervention (158/1661) and 7.7% among control households (115/1498) (SAR ratio 1.24, 95% CI 0.92–1.65). The SAR ratio for influenza was 2.40 (95% CI 0.68–8.47). In the control arm, susceptible contacts <2 years old (RR_adj 5.51, 95% CI 3.43–8.85), those living with an index case-patient enrolled ≤24 hours after symptom onset (RR_adj 1.91, 95% CI 1.18–3.10), and those who reported multiple daily interactions with the index case-patient (RR_adj 1.94, 95% CI 1.71–3.26) were at increased risk of influenza-like illness.</p><p>Discussion</p><p>Handwashing promotion initiated after illness onset in a household member did not protect against influenza-like illness or influenza. Behavior may not have changed rapidly enough to curb transmission between household members. A reactive approach to reduce household influenza transmission through handwashing promotion may be ineffective in the context of rural Bangladesh.</p><p>Trial Registration</p><p>ClinicalTrials.gov <a href="http://clinicaltrials.gov/ct2/show/NCT00880659?term=NCT00880659&rank=1" target="_blank">NCT00880659</a></p></div

Impact of intensive handwashing promotion on secondary attack risks (SAR) of influenza-like illness, and influenza, among household compound members of index case-patients, Kishoregonj, Bangladesh, 2009–2010.

<p>*All susceptible contacts in both index case-patient and secondary households included.</p><p>**Confidence intervals and P-values generated using log binomial regression model with generalized estimating equations to estimate significance of ratio of secondary attack risks in treatment arms.</p><p>Impact of intensive handwashing promotion on secondary attack risks (SAR) of influenza-like illness, and influenza, among household compound members of index case-patients, Kishoregonj, Bangladesh, 2009–2010.</p

Individual-level risk factors for secondary transmission of influenza-like illness among susceptible household members in the control arm, Kishoregonj, Bangladesh, 2009–2010 (N = 1498).

<p>¹ Attack rates for influenza-like illness calculated for susceptible members in the control arm who were exposed and unexposed to each characteristic at baseline. Attack rate ratios and confidence intervals generated using log binomial regression models, with generalized estimating equations to account for clustering among household members.</p><p>^<b>2</b>Analysis restricted to household members of index case-patients > 5 years old.</p><p>^<b>3</b>Information missing for 295 household members.</p><p>^<b>4</b>Only queried in 2010.</p><p>^<b>5</b>Only reported for members of index case-patient household.</p><p># multivariable model includes the following variables: contact < 2 years old (or contact < 5 years old); Index case-patient with fever onset 24 hours prior to enrollment; and contact interacts multiple times daily with index case-patient.</p><p>Individual-level risk factors for secondary transmission of influenza-like illness among susceptible household members in the control arm, Kishoregonj, Bangladesh, 2009–2010 (N = 1498).</p

Multivariable analysis of impact of intensive handwashing promotion on secondary attack risks (SAR) of influenza-like illness, and influenza, among household compound members of index case-patients, Kishoregonj, Bangladesh, 2009–2010.

<p>Multivariable analysis of impact of intensive handwashing promotion on secondary attack risks (SAR) of influenza-like illness, and influenza, among household compound members of index case-patients, Kishoregonj, Bangladesh, 2009–2010.</p

Baseline characteristics of index case-patients, household compounds, and household members, by treatment arm, Kishoregonj, Bangladesh, 2009–2010.

<p>*Data not collected for 67 children, all of whom were under 5 years old and enrolled in 2009.</p><p>**Only queried in 2010; denominators were 934 for intervention arm and 890 for control arm.</p><p>***Only reported for members of index case-patient household; denominators were 863 in the intervention arm and 727 in the control group.</p><p>Baseline characteristics of index case-patients, household compounds, and household members, by treatment arm, Kishoregonj, Bangladesh, 2009–2010.</p

Flow diagram to describe screening, inclusion, exclusion, and randomization, Kishoregonj, Bangladesh, 2009–2010.

<p>Flow diagram to describe screening, inclusion, exclusion, and randomization, Kishoregonj, Bangladesh, 2009–2010.</p

Cumulative age-specific viral etiology of hospitalized children with respiratory illness aged <5 years enrolled in the four surveillance hospitals, Bangladesh, 2010–2014.

<p>Cumulative age-specific viral etiology of hospitalized children with respiratory illness aged <5 years enrolled in the four surveillance hospitals, Bangladesh, 2010–2014.</p

Monthly distribution of total number of enrolled hospitalized children with respiratory symptoms andproportion of children with respiratory symptoms positive for respiratory syncytial virus, human metapneumovirus, parainfluenza, influenza, adenovirus and rhinovirus infection in the four surveillance hospitals, Bangladesh, 2010–2014.

<p>Monthly distribution of total number of enrolled hospitalized children with respiratory symptoms andproportion of children with respiratory symptoms positive for respiratory syncytial virus, human metapneumovirus, parainfluenza, influenza, adenovirus and rhinovirus infection in the four surveillance hospitals, Bangladesh, 2010–2014.</p