Disease Levels

Endemic

An endemic is a disease that is limited to a particular population or country. It is the observed prevalence of a disease in a community, within a certain geographic area. 

List of Notifiable Diseases in Sri Lanka

Epidemic 

An epidemic is a disease that affects a large number of people within a population or region. Epidemic refers to a sudden increase in the number of cases of a disease above the normal value observed in that population in that area.

The outbreak is similar to the epidemic but it is used for a more limited geographic area.

• The 1965 outbreak of chikungunya. It originated in Colombo and spread along the south-western coastal belt from Negombo to Matara from May to June of that year.
• The reemergence of chikungunya in Sri Lanka in 2006–07 in an epidemic with more than 40 000 suspected cases. It affected districts along the coastal belt, including Batticaloa, Colombo, Jaffna, Kalmunai, Mannar, Puttalam and Trincomalee. The districts of Kandy, Kurunegala and Matale were less affected

• Recent Dengue Outbreaks

Year	Details of Outbreak
2017	The country reported over 180 000 cases and 440 dengue related deaths in 2017. More than 40% of the cases were from the western province and the most affected area with the highest number of reported cases is Colombo District followed by Gampaha, Kurunegala, Kalutara, Batticaloa, Ratnapura and Kandy.
2009	In early 2009, nearly 600 cases of dengue, including 5 deaths, were notified over a 3-week period, with most cases arising from the areas of Colombo, Embilipitiya, Gampaha, Kandy, Matale and Ratnapura.
2004	Of 15408 cases, 88 deaths occurred (CFR = 0.57%). Cases were reported from 25 districts, with 72% of cases and 78% of deaths from five cities (Colombo, Kandy, Gampaha, Kalutara and Kurunegala) (CFR = 0.4–1.1%).
1996	There were 289 cases from the Kurunegala district, and focal outbreaks occurred in the provincial towns of Batticaloa, Galle and Kandy.
1990	Of 1350 cases, 363 were serologically confirmed.
1989	Of 203 clinically diagnosed cases, 20 deaths occurred (CFR = 9.8%).
1965–68	Of 51 cases of DHF, there were 15 deaths. Most towns throughout the country were affected during this outbreak, but the greatest impact was felt in the western coastal belt.

Source: WHO, 2017.

• In 2007, an epidemic of hepatitis A broke out in the Gampola area in the Kandy district of Sri Lanka. About 200 people were admitted to a hospital in Gampola. Their cases were thought to result from the consumption of contaminated water. Cases peaked in the second and third quarter of 2007.
• From 1868 to 1948 there have been 20 malaria epidemics in Sri Lanka.

• Major malaria epidemics:

1. Malaria epidemic in 1934-35 affected one and a half a million people out of a population of five and a half million. There were over 80 000 deaths within seven months.
2. In 1969 537,700 registered cases were reported.
3. The epidemic in 1975 produced 400,700 cases.
4. Thereafter, there have been epidemics in 1983 (127,000), 1987 (680,000 cases), 1991–2 (400,000 cases) and 1999 (290,000 cases).

Pandemic

A pandemic is an epidemic (sudden increase in the number of cases) that is spread over multiple countries or continents with a high number of cases. 

Past Pandemics

• 2009 pandemic

The first influenza pandemic of the 21st century occurred in 2009–2010 and was caused by an influenza A(H1N1) virus. While most cases of pandemic H1N1 were mild, globally it is estimated that the 2009 pandemic caused between 100 000–400 000 deaths in the first year alone. 

• The 1918-19 influenza caused by A(H1N1) virus, pandemic spread over the entire world in less than six months and killed tens of millions of people. This influenza spread in three distinct waves. 

The Influenza Pandemic in Sri Lanka

The influenza was first reported in June 1918, mortality from the influenza increased noticeably only in September 1918. The Registrar-General for Ceylon reported 41 916 deaths due to influenza (excluding pneumonia and other complications) in 1918–1919. At the time, the number of deaths registered in 1918 was ‘the highest ever recorded in Ceylon in any single year’, and ‘this comparatively high mortality is due to the influenza pandemic’.

The first cases of influenza appeared in June of 1918 in Colombo, the capital city and main port, among harbour workers, and the disease spread from there. The influenza entered Sri Lanka through two separate locations, Colombo in the south and Talaimannar in the northwest. Coastal districts in the north, northeast and west and districts in the southwest near Colombo were affected initially. Subsequently, the disease spread to the interior of the island and to other districts in the south. Probably about 1.1 per cent of the population died.

It caused extremely high numbers of deaths on the island and affected different regions in at least two distinct and severe waves. The first and relatively mild wave occurred in the summer of 1918, only to be followed by a more severe second wave in the autumn of 1918 and a third wave in the spring of 1919.12 The second wave was far more virulent and widespread than the first wave, and lasted from October to December 1918, with pockets continuing into January and even February 1919.

• Milder pandemics occurred subsequently in 1957–1958 (the “Asian Flu” caused by an A(H2N2) virus) and in 1968 (the “Hong Kong Flu” caused by an A(H3N2) virus), which were estimated to have caused 1–4 million deaths each.