Establishment of Influenza Surveillance System in Liberia

1. Establishment of Influenza Surveillance System in Liberia Presented By DIDE

2. Background • Influenza virus spreads rapidly around the world in seasonal epidemics, resulting in significant morbidity and mortality • The burden of influenza in the USA is currently estimated • to be 25–50 million cases per year, leading to 150 000 hospitalizations and 30 000–40 000 deaths. • If these figures are extrapolated to the rest of the world, • the average global burden of inter-pandemic influenza may be on the order of ~1 billion cases of flu, ~3–5 million cases of severe illness and 300 000–500 000 deaths annually. • Epidemics and outbreaks of influenza occur in different seasonal patterns depending on the region in the world • Annual global attack rates for influenza are approximately 5- 10% in adults, with significantly higher attack rates 20-30% in children.

3. Background • In temperate climate zones, seasonal epidemics typically begin in the late fall and peak in mid- to late winter. • In tropical zones, seasonal patterns appear to be less pronounced, with year-round isolation of virus. • An outbreak will reach its peak within 2-3 weeks and may last around 8 weeks in a given community after the onset of outbreak • The first indication of an influenza outbreak might be signaled by an event, such as increase in school absenteeism due to acute respiratory diseases. • Annual global attack rates for influenza are approximately 5- 10% in adults, with significantly higher attack rates 20-30% in children.

4. Epidemiology • Influenzais an acute viral respiratory tract disease in humans, often characterized by • fever, headache, myalgia, prostration, coryza, sore throat and cough. • Influenza infection is clinically indistinguishable from other respiratory viral diseases without laboratory confirmation. • Etiology: • Influenza infection is caused by the influenza virus, a single-stranded RNA virus belonging to the Orthomyxoviridae family. Influenza viruses are classified as types A, B and C. • Types A and B viruses can cause epidemic disease in humans • Natural reservoirs of influenza A are aquatic birds and bats; however, the virus can infect multiple species, including humans, pigs and other mammals and wild and domestic birds.

5. Figure 1: Case definitions for Influenza Like Illness and Severe Acute Respiratory Illness Source: Protocol for national influenza sentinel surveillance (2015), Congo Brazzaville, World Health Organization. Regional Office for Africa

6. Rationale • To support member states in the development of sensitive influenza surveillance in the context of the Integrated Disease surveillance & Response (IDSR) • Training modules on influenza surveillance have been developed in cooperating the three main components of surveillance: • Epidemiological surveillance • Virological surveillance • Data management • Liberia is currently not conducting active influenza surveillance, WHO would like to support Liberia to establish Sentinel surveillance for influenza • This will entail selection of a sentinel site, training of personnel and thereafter implementation of sentinel surveillance

7. Objectives of influenza Surveillance • General Objective: • Provide timely epidemiological and biological data so as to better inform national prevention and control activities including immunization • Specific Objectives: • Characterize and monitor trends of influenza-associated illnesses and deaths attributable to mild and/or severe acute respiratory illness • Provide data to identify and monitor groups at high risk for severe disease and mortality • Provide information to establish baseline levels of activity for influenza-like illness (ILI) • Monitor antiviral resistance/sensitivity of circulating influenza viruses and severe acute respiratory illness (SARI) • Identify locally circulating influenza types and subtypes and their relationship to global and regional patterns • Detect new circulating strains

8. Guiding Points • It is recognized that all objectives may not be achieved by every system, especially when • resources are limited • It is crucial to establish surveillance systems to • enable detection and investigation of the first evidence of sustained human-to-human transmission of an influenza virus with pandemic potential • Under the IHR (2005), a State Party is required to notify WHO of the first occurrence of human influenza caused by a new subtype Figure 3: Relationship between IDSR and IHR in Influenza Surveillance

9. Activity Plan

10. Thank You