Sri Lanka faced an unpredicted outbreak of dengue fever. It is a tropical country with two monsoon seasons. With each monsoon brings in two peaks of dengue fever making it an endemic disease in Sri Lanka.

1. Dengue Fever
Sri Lanka
W. P. Rivindu H. Wickramanayake
Group no. 04a
3rd Year 2nd Semester – 2017 December
Tbilisi State Medical University, Georgia

2.  Dengue infection is caused by Arboviruses.
 Arboviruses are also called as Arthropod borne viruses, represent
an ecological grounding of viruses with complex transmission
cycles involving Arthropods.

3. Dengue - History
 This disease was first described 1780.
 Dengue virus was isolated by Sabin 1944.
 Dengue virus infection is the most common arthropod-borne infection
is the most common arthropod-borne disease worldwide with an
increasing incidence disease worldwide,
 with an increasing incidence in the tropical regions of Asia, Africa,
and Central and South America.
 There are four serotypes of the virus.
 All are transmitted by mosquitoes, which are not affected by the
disease, although an infected mosquito may infect others (not via man).

4.  Despite the presence of dengue in Sri Lanka since the early 1960s, dengue has
become a major public health issue, with a high morbidity and mortality.
 Aedes aegypti and Aedes albopictus are the vectors responsible for the
transmission of dengue viruses (DENV).
 The four DENV serotypes (1, 2, 3, and 4) have been co-circulating in Sri Lanka
for more than 30 years.
 The new genotype of DENV-1 has replaced an old genotype, and new clades of
DENV-3 genotype III have replaced older clades.
 The emergence of new clades of DENV-3 in the recent past coincided with an
abrupt increase in the number of dengue fever (DF)/dengue hemorrhagic fever
(DHF) cases, implicating this serotype in severe epidemics.
Evolution of dengue in Sri Lanka –
changes in the virus, vector, and climate

5.  Climatic factors play a pivotal role in the epidemiological
pattern of DF/DHF in terms of the number of cases, severity of
illness, shifts in affected age groups, and the expansion of spread
from urban to rural areas.
 There is a regular incidence of DF/DHF throughout the year, with
the highest incidence during the rainy months.
 To reduce the morbidity and mortality associated with DF/DHF, it
is important to implement effective vector control programs in
the country.
 The economic impact of DF/DHF results from the expenditure on
DF/DHF critical care units in several hospitals and the cost of case
management.

6. Historical Account of Dengue
Hemorrhagic Fever in Sri Lanka
 Sri Lanka is an island situated 34 kilometres south of India. It has an
area of 65610 sq km and a population of 18.3 million, 22% of whom
live in urban areas and the rest in rural areas.
 Clinical dengue-like illness has been recorded in Sri Lanka since the
beginning of the century, and it was serologically confirmed in 1962.
 Following a Chikungunya outbreak in 1965, there was an island-
wide epidemic of dengue associated with DEN types 1 and 2, with 51
cases of DHF and 15 deaths in the period 1965-1968.
 From 1969 up to 1988, multiple dengue serotypes circulated in urban
areas with endemic DF, but there were only occasional cases of DHF.

7.  From 1989 onwards, DHF has become endemic in Sri Lanka and there have
been 203 hospitalized clinical cases of DHF, of whom 37% were serologically
confirmed and 20 deaths, giving a case fatality rate (CFR) of 9.8% (Figure).
 There was a sharp rise in 1990 with 1350 suspected DHF cases, of whom 363
were serologically confirmed, and there were 54 deaths (CFR 4.0%).
 During the period 1991-1995, between 440 and 1048 cases were reported each
year with a CFR of about 4%.
 However, in 1996, there was an epidemic with 1298 clinically-diagnosed cases
of DHF hospitalized and 54 deaths (CFR 4.2%).
 Because of deficiencies in reporting it is likely that the actual number of cases
was more.
 In 1989, the DHF cases initially occurred mainly in and around Colombo, but
they progressively spread to other towns and reached outbreak proportions in
several provincial capitals, e.g. Kurunegala, Galle, Kandy and Batticoloa in
1996.

8.  The age distribution pattern shows a preponderance in children under 15 years
(65%), with a peak in the 5-9-year age group.
 It is noteworthy that there has been a significant number of cases in the 15-29-
year age group, especially between 15-19 years.
 The sex distribution does not show any significant male-to female difference.
 There is a close correlation of the occurrence of DF/DHF with the rainfall
and the peak levels are reached with the south-west monsoon (May to July)
and the north-east monsoon (October to December).
 Entomological studies conducted by the Medical Research Institute (MRI)
indicate that over 90% of the breeding of Aedes aegypti and Aedes albopictus
occurs in small outdoor containers like tins, coconut shells, bottles, plastic
containers, rubber tyres, etc. Indoor water storage is not widely practiced in
Sri Lanka.
 The main serotypes associated with DHF since 1989 have been DEN-2 and 3.
References: Dengue fever and DHF in Sri Lanka. WHO/SEARO, Dengue Newsletter, 1993, 18:12.

10. Current Trends
 Sri Lanka is reporting an increased number of dengue cases this year.
From 1 January to 7 August 2017, the Epidemiology Unit of the
Ministry of Health, Sri Lanka reported 122 384 dengue cases, with a
significant number of cases reported from the Western Province
(Approximately - 43%).
 The number of dengue cases peaked in June 2017, coinciding with
the South-West monsoon rains which commenced in late May.
 Heavy monsoon rains, standing water pools and other potential
breeding grounds for mosquito larvae attribute to the higher
number of cases reported in urban and suburban areas.

11. Current Trends; Additional
 Since January until 7 July 2017, as many as 82,543 dengue cases, including 250
deaths, have been reported by the Ministry of Health, Nutrition and Indigenous
Medicine.
 The number of cases this year is three-and-a-half times more than the average
number of cases for the same period between 2010 and 2016.
 The most affected areas are the;
 Colombo district, 18,761 cases;
 Gampaha, 12,121 cases;
 Kurunegala, 5,065 cases;
 Kalutara, 4,589 cases and
 Kandy, 4,209 cases.
 The current dengue outbreak follows heavy rains and subsequent flooding and
landslides, which affected 600 000 people in 15 of the 25 districts in the
country. (WHO, 11 Jul 2017)

12. Measures going on
 WHO is providing technical assistance to the Government to control the
dengue outbreak.
 On the request of the Minister of Health, WHO has supported the MOH to
develop a plan to address the dengue outbreak, bring down the caseload and
reduce the case fatality.
 Situation Reports;
1) Situation Report No. 1: 11 July 2017
2) Situation Report No. 2: 17 July 2017
3) Situation Report No. 3: 28 July 2017
 Press Releases;
1) Rapid vector control, personal protection key to curtail dengue

13.  Cases reported in August is reduced to 14,962 when compared to
40,453 cases reported in July. The main reasons for the reduction is
the integrated vector control measures; elimination of breeding
sites, garbage collection, fogging etc. (IFRC, 6 Sep 2017)
 A total of 155,715 suspected Dengue cases have been reported to the
Epidemiology Unit of the Ministry of Health (MOH) of Sri Lanka from
all over the island, for the last 9 months of 2017 with over 320 deaths.
(IFRC, 9 Oct 2017)
 From January through November 2017, a total of 174,009
suspected cases of Dengue fever were reported to the Epidemiology
Unit of Sri Lanka's Ministry of Health, with a peak observed in June
and July. (Govt. Sri Lanka, 30 Nov 2017)

14.  Useful Links / References;
1) WHO Country Office for Sri Lanka: Dengue
2) Sri Lanka Ministry of Health: Distribution of Notification (H399) Dengue
Cases by Month

17. Public Health Response
 World Health Organization (WHO) is supporting the MOH Sri Lanka to ensure
an efficient and comprehensive health response and the following response
measures include:
1) Support from the military forces has been requested by the MoH to increase
the number of beds as the health care facilities are overwhelmed. Three temporary
wards in a hospital 38km north of Colombo have now been completed.
2) The MoH launched an emergency response including vector control activities
that is also supported by the mobilization of defense forces. The army, police and civil
defense forces have been mobilized to conduct house-to-house visits in the high-risk
areas with health staff.
In addition, they are involved in mobilizing the community for garbage
disposal, cleaning of vector breeding sites, and in health education.
3) The Regional Office for South-East Asia (SEARO) has constituted a Task
Force to guide the response.

18. 4) WHO/ SEARO deployed an epidemiologist, an entomologist and two dengue
management experts from the WHO Collaborating Center for case management of
Dengue/Dengue Haemorrhagic Fever (Queen Sirikit National Institute of Child Health,
Thailand) and Ministry of Public health (MoPH) Thailand.
5) The triage protocol was updated in June 2017 to assist with better management
of the patients in the health facilities.
 The WHO Sri Lanka country office has purchased 50 fogging machines to
support vector control activities.
 MOH and WHO have worked together to prepare a strategic and operational
plan for intensive measures to control dengue outbreak in next few weeks.
Reference;
1) Emergency Plan of Action operation update Sri Lanka: Dengue by IFRC

21. https://www.youtube.com/watch?time_continue=69&v=TykFhNhttqM
For Sinhala Language Version;
http://www.dengue.lk

22. WHO Risk Assessment
 Dengue fever is a mosquito-borne viral infection caused by four dengue virus
serotypes (DENV-1, DENV-2, DENV-3, and DENV-4).
 Infection with one serotype provides long-term immunity to the
homologous serotype but not to the other serotypes; secondary infections put
people at greater risk for severe dengue fever and dengue shock syndrome.
 Aedes aegypti and Aedes albopictus are the vectors widely adapted to urban and
suburban environments.
 Dengue fever is endemic in Sri Lanka, and occurs every year, usually soon after
rainfall is optimal for mosquito breeding.
 However DENV-2 has been identified only in low numbers since 2009 and is
reportedly over 50% of current specimens which have been serotyped.
 The current dengue epidemic is likely to have repercussions on public health in
Sri Lanka.

23. WHO Advice
 WHO promotes the strategic approach known as Integrated Vector
Management (IVM) to control mosquito vectors, including those of
dengue.
 The proximity of mosquito vector breeding sites to human
habitation is a significant risk factor for dengue virus infection.
 Prevention and control relies on reducing the breeding of mosquitoes
through source reduction (removal and modification of breeding
sites) and reducing human–vector contact through adult control
measures. Both control measures need to implemented
simultaneously for effective control.

24.  This can be achieved by reducing the number of artificial water containers
that hold water (cement tanks for water storage, drums, used tyres, empty
bottles, coconut shells, etc.) in and around the home and by using barriers such
as insect screens, closed doors and windows, long clothing and use of insect
repellents, household insecticide aerosol products, mosquito coils etc. and
space spraying with insecticide can be deployed as an emergency measure.
 As protection from the Aedes mosquitoes (the primary vector for transmission),
it is recommended to sleep (particularly young children, the sick or elderly)
under mosquito bed nets, treated with or without insecticide.
 WHO does not recommend that any general travel or trade restrictions be
applied on Sri Lanka based on the information available for this event.
Reference: http://www.who.int/csr/don/19-july-2017-dengue-sri-lanka/en/