Published On: Wed, Nov 13th, 2013

Influenza Season In The Caribbean

InfluenzaPORT OF SPAIN, Trinidad (CARPHA) -- Seasonal influenza affects many thousands of people in the Caribbean each year.

It is an infectious respiratory disease that is associated with the circulation of one or more of three influenza virus types: A, B and less commonly type C. Influenza viruses A and B cause seasonal epidemics yearly during autumn and winter in temperate regions. In some tropical countries, influenza viruses circulate throughout the year with one or two peaks during rainy seasons. Worldwide, annual epidemics can result in about three to five million cases of severe illness, and about 250,000 to 500,000 deaths. Most deaths associated with influenza occur among people aged 65 years and older.

Seasonal influenza can cause mild to severe illness, and at times can lead to death. It is characterized by symptoms such as a sudden onset of high fever, cough (usually dry), headache, muscle and joint pain, severe malaise (feeling unwell), sore throat and runny nose. Most healthy adults may be able to infect others beginning one day before symptoms develop and up to 5 to 7 days after becoming sick. Most people recover from fever and other symptoms within a week without requiring medical attention. In some cases, illness can be severe resulting in hospitalizations and deaths, mainly among people at greater risk for serious complications if they become infected. This includes older people, young children, pregnant women, people with certain chronic health conditions (such as asthma, diabetes, or heart disease), and persons living in facilities like nursing homes.

Influenza viruses are divided into different subtypes, and before 2009 the prevalent subtypes were influenza A(H3N2), and influenza A(H1N1). Early 2009 witnessed the emergence of a new influenza A virus subtype in the Americas, influenza A(H1N1)pdm09 virus (also referred to as 2009 H1N1 influenza virus). As the virus spread around the world, the World Health Organization (WHO) declared it a pandemic influenza virus. Because it was a new strain of influenza and because human populations had little or no natural immunity to this virus, it caused widespread illness. On August 10, 2010, WHO declared that the H1N1 pandemic over and the world had entered the post-pandemic period. This decision was informed by epidemiological evidence from around the world showing that the A(H1N1)pdm09 influenza virus was circulating at lower levels and behaving like a seasonal influenza virus. The Caribbean region recorded a high prevalence of this subtype in 2010, and since the end of the 2009 H1N1 pandemic, the A(H1N1)pdm09 influenza virus continues to circulate in the Caribbean at low levels.

In 2011 and 2012, the A(H1N1)pdm09 influenza virus co-circulated with influenza A(H3N2) and influenza B viruses following the expected seasonal pattern. During 2013, the A(H1N1)pdm09 influenza virus has been the subtype of the highest prevalence in the Caribbean, Central and South American (Figure 1). To date, the virus has been genetically stable and the actual activity recorded in the region is the expected seasonal activity without new pandemic potential.

Influenza A(H5N1), commonly referred to as “avian influenza” has not been detected in the Caribbean region. Although human infection with this virus is rare, sporadic cases of human infection have been reported. Indonesia, Vietnam and Egypt have reported the highest number of human HPAI H5N1 cases to date.


The influenza virus spreads mainly by droplets made when people with influenza cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs. Less often, a person might also get flu by touching a surface or object that has the influenza virus on it and then touching their own mouth or nose.

To avoid this, people should stay away from sick people and stay home if sick. It also is important to wash hands often with soap and water, particularly before and after eating, after visiting a public place, after using the washroom, after coughing and sneezing and after touching surfaces that may have been contaminated. People should observe respiratory etiquette by coughing and sneezing into their arm, and not their hand.  If a tissue is used it should be disposed of as soon as possible and then followed by handwashing. If soap and water are not available, an alcohol-based hand rub may be used. Linens, eating utensils, and dishes belonging to those who are sick should not be shared without washing thoroughly first. Eating utensils can be washed either in a dishwasher or by hand with water and soap and do not need to be cleaned separately from other utensils. Further, frequently touched surfaces should be cleaned and disinfected at home, work and school, especially if someone is ill.

The most effective way to prevent the disease or severe outcomes from the illness is vaccination. Safe and effective influenza vaccines have been available and used for more than 60 years. Among healthy adults, influenza vaccine can prevent 70% to 90% of influenza-specific illness. Among the elderly, the vaccine reduces severe illnesses and complications by up to 60%, and deaths by 80%.

Vaccination is especially important for people at higher risk of serious influenza complications, and for people who live with or care for high risk individuals.

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