Infectious Diseases Surveillance in the Military LTC (Dr) Vernon Lee MBBS, PhD, FAMS, MPH,MBA Singapore Armed Forces Biodefence Centre

Surveillance “Timely surveillance system that collects information on epidemic prone diseases in order to trigger prompt health interventions” Monitoring of infectious diseases that impact Singapore Armed Forces (SAF) servicemen and operations Includes epidemiological analytics and mathematical modelling Local disease outbreak surveillance Regional and international disease situation, e.g. MERS-CoV, Ebola

Why Military Surveillance Military personnel face unique physical and mental stressors Impact on immunity Close-proximity living and working environments Conduit for transmission of diseases Different health seeking behavioural patterns The military among the first to detect pandemic influenza cases in Singapore in 1957, 1968 and 2009

Singapore Armed Forces’ Early Warning System Acute Respiratory Illness (ARI) surveillance Programme Since 2009 across 4 sentinel sites Enteric Pathogen Prevalence Study Nov 2013 to Nov 2014

ARI Surveillance Cases Acute onset Fever >37.5 ºC with cough and/or sore throat Controls No acute onset fever or respiratory symptoms in past 14 days Without any infectious disease Nasal washes obtained Tested at DSO National Laboratories PCR for 17 viral and bacterial pathogens Sequencing and characterisation where relevant Questionnaire on demographics, clinical signs/symptoms, potential risk factors obtained

Utilising Surveillance Data For Medical Protection Policies : Influenza vaccination 2010 2011 2012 2013 2014

Effectiveness of seasonal influenza vaccinations Ho et al, Influenza Other Respir Viruses. 2014 Sep; 8(5): 557–566. 7,016 influenza cases Vaccine efficacy against both influenza A(H1N1)pdm09 and influenza B were 84% 95% CI 78–88% and 79– 86% Vaccine efficacy against influenza A(H3N2) was markedly lower at 33%, 95% CI 4% to 57% Reduction in risk post-vaccination vs pre-vaccination in recruit camp 70% (RR = 0.30; 95% CI 0.11–0.84) for A(H1N1)pdm09 39% (RR = 0.61; 0.25 – 1.43) for A(H3N2) 75% (RR = 0.25; 95% CI 0.11–0.50) for influenza B

Influenza profiling and comparison with national data MOH SAF

Adenovirus Surveillance Following successful implementation of influenza vaccination, there was an increasing trend of adenovirus being detected Potential implementation of Adenovirus vaccination in the SAF But are the strains detected similar to the vaccine strains?

Temporal Distribution of Adenovirus Types (Jun 2009 - Jul 2014) Time 1 : Jun-09 to Dec-10 6 : Jan-12 to Mar-12 11 : Apr-13 to Jun-13 2 : Jan-11 to Mar-11 7 : Apr-12 to Jun-12 12 : Jul-13 to Sep-13 3 : Apr-11 to Jun-11 8 : Jul-12 to Sep-12 13 : Oct-13 to Dec-13 4 : Jul-11 to Sep-11 9 : Oct-12 to Dec-12 14 : Jan-14 to Mar-14 5 : Oct-11 to Dec-11 10 : Jan-13 to Mar-13 15 : Apr-14 to Jul14

Circulating Adenovirus Types (Jun 2009 - Jul 2014) Frequency E* 671 C1 40 C2 51 C5 23 C6 2 B3 92 B7* 42 B21 9 B55 1 B 30 U 10 Total (including 20 co-infections 971

Sequencing of hexon gene from Adenovirus B7

Sequencing of hexon gene from Adenovirus B7

Enteric Disease Surveillance

Enteric Pathogen Prevalence Study The selection criteria of cases include: Acute onset At least 3 times watery stool and/or 2 times vomiting within 24 hours; and For controls, the selection criteria include: Patients without diarrhoea or vomiting in last 14 days; and Without disease suggestive of an infectious cause 702 subjects recruited over 1 year

Pathogen prevalence Chart:

GID-related viruses trends

GID-related viruses trends

GID-related viruses trends

GID-related Bacteria Trends

GID-related Parasites Trends

Emergence of norovirus GI.2 outbreaks in military camps in Singapore ZJM Ho et al, Int J Infect Dis. 2015 Feb;31:23-30. Simultaneous gastroenteritis outbreaks at 2 camps 775 persons involved Camp A (21 days, attack rate 15.0%). Camp B (6 days, attack rate 8.3%) Investigations included epidemiological surveys, hygiene inspections, and testing of water, food, and stools PCR and sequencing of relevant samples

Findings Norovirus GI.2 detected in 32.5% (larger camp) and 28.6% (smaller camp) of stool samples Identical to norovirus detected in two preceding community outbreaks Antigenic site homology modelling showed differences with more common norovirus GII.4 Greater propensity for transmission within large camps with a high population density? Why do certain noroviruses cause outbreaks?

Future surveillance programs Routine enteric disease surveillance Future extension to other febrile illness and returning travellers Setting outbreak detection thresholds through modelling of surveillance data Sero-epidemiology studies for vaccine-preventable diseases

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