2017 dengue outbreak in Sri Lanka

In the 2017 dengue epidemic in Sri Lanka, a rise in the number of dengue fever cases was reported on the island country of Sri Lanka. The peak of the outbreak was in the mid-year monsoon rain season, when there was record of over 40,000 cases in July. This figure was far beyond the historical highest number of cases per month in Sri Lanka. Year end total dengue cases rose to 186,101.

2017 dengue outbreak in Sri Lanka
DiseaseDengue fever
Virus strainDengue virus
First outbreakSri Lanka
DatesMay 2017 – Aug 2017
Type
DENV-2
Confirmed cases186,101
Deaths
440
Fatality rate0.24%
Vaccinationsno vaccine available (at time)

Most cases (43%) were recorded in Western Province urban areas such as the Colombo district (table 1).[1] Most dengue cases were young people and school children. Year end Sri Lanka's total dengue related deaths was 440.

The Government of Sri Lanka spend more than US$12 million on outbreak control and was supported by NGOs such as the Red Cross.[2][3][4]

Table 1 - Dengue Cases by Three Exemplar Districts (2017)[5]
District January February March April May June July August September October November December Total
Colombo 2,734 1,900 2,467 2,570 3,333 5,372 7,471 3,620 1,251 823 1,131 1,602 34,274
Gampaha 1,635 1,087 1,870 2,072 3,168 4,901 9,039 3,553 1,246 779 1,078 1,219 31,647
Kalutara 581 448 836 739 946 1,248 2,612 1,477 663 337 528 546 10,961

Background

In 2017 Sri Lanka experienced its largest neglected tropical disease outbreak of dengue fever since the first recorded Sri Lankan case in 1962.[6][7][8] This biological hazard, transmitted via female mosquito bites, caused 186,101 dengue cases, significantly higher than in previous years (table 2), and 440 deaths.[3][9][10]

Table 2 - Annual Dengue Case Numbers from 2010-2022, Sri Lanka[11]
Year 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Annual Dengue Cases 34,188 28,473 44,461 32,063 47,502 29,777 50,592 186,101 51,659 105,049 31,162 25,067 51,005 (Jan-Oct)
Figure 1 - Comparison of weekly mean attack rates of dengue reported in 2017, Sri Lanka. Rates are cases per 100,000.[3]
Figure 2 - Comparison of dengue incidence rates per district in 2017, Sri Lanka. Incidence is cases per 100,000.[3]

Sri Lanka's Ministry of Health (MoH) reported a rise in cases from January, with the highest number of cases reported in July (table 3 & figure 1).[11] Most cases were recorded in the west and north of the country, specifically in the urban Colombo district (figure 2).[3]

Table 3 - 2017 Monthly Dengue Cases, Sri Lanka[11]
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Reported Dengue Case Numbers 10,927 8,724 13,540 12,540 15,963 25,319 41,121 22,270 9,519 6,614 8,868 10,753

Climate
  • Sri Lanka's tropical climate offers prime mosquito breeding conditions.[12]
  • The 2017 monsoon rains (May–August) coincided with the peak of the dengue outbreak (table 2). Triggering floods and disrupting refuse collection, increasing mosquito breedings sites.[8][13]
  • However, annual rainfall and El Nino conditions were lower on average than previous years, suggesting that climate was not completely responsible for the outbreak.[3]

Political
  • MoH failed to prepare and take appropriate mosquito vector control.[7][14]
  • Insufficiencies in the virologic surveillance programme failed to identify dengue serotypes and genotypes.[7][8][15] Leaving Sri Lanka unprepared for new strains (DENV-2), for which their population would have little immunity.[1][3][15]

Socio-economic
  • Sri Lanka is a middle-income country with a GDP per capita of US $12,600 (2017).[16] This restricts investment in healthcare infrastructure resulting in an overstretched healthcare system.[8]
  • High urban population density in western districts (figure 2) created higher probability of transmission.[3]
  • In 2017, 42% of Sri Lankans were in extreme poverty (below US$5.50 a day) which limits a family's access to healthcare and increases risk of disease.[16][17]
  • Regional disparities, due to the Sri Lankan civil conflict (1983-2009), displaced people to IDP camps and marginalised ethnic groups (Tamils) in north and eastern districts, reducing support and increasing disease risk.[18][19]

Short- and long-term impacts

Short-term impacts
  • Unexpected high death toll.[8]
  • Figure 3: Dengue incidence rates by age group and sex, Sri Lanka, 2017. Incidence is cases per 100,000 population.[3]
    Disruption to workplaces, household income, and education as the majority of cases were of people aged 10–29 (figure 3).[3]
  • Direct and indirect impacts of the dengue outbreak affected 600,000 people, in all 25 districts, prominently in urban areas.[1] However, some districts may have been under-reported due to ethnic marginalisation and the presence of IDP camps.[18][20]
  • Dengue treatment strained national economic resources costing Sri Lanka US $12.7 million (LKR 1.938 billion).[3]

Long-term impacts
  • Today dengue cases are declining in Sri Lanka, with 25,067 total cases in 2021 (table 1).[11]
  • Dengue is still present with new strains (serotypes DENV-3 and DENV-4) becoming more prominent threatening future outbreaks.[15]
  • Combined with the COVID-19 pandemic there is still immense pressures on healthcare and trade networks.[21]
  • 2022 has seen an economic crisis and severe food insecurity in Sri Lanka, the dengue outbreak would be a contributing factor.[22][23]

Futures

Climate change models suggest that Sri Lanka's climate is becoming more conducive to mosquito breeding, this combined with economic instability could trigger a future epidemic.[23][24] There is a possibility of a cycle of disease, poverty and food insecurity which may be challenging to break.[25] However, this could be mitigated if the MoH, supported by institutions like WHO, engage in proactive strategies.[21] At the cost of US$78 per person a licensed vaccine is now available Dengvaxia® (CYD-TDV) with five more in development.[21] However, Sri Lanka's current expenditure is US$161 per capita on healthcare (2021), the vaccine is a significant proportion of that budget and in uncertain economic times may not be a priority.[26][27]

See also

References
  1. "WHO | Dengue fever – Sri Lanka". WHO. Archived from the original on July 21, 2017. Retrieved 2020-11-27.
  2. "Sri Lanka: Dengue Outbreak - Jul 2017". ReliefWeb. Retrieved 2020-11-27.
  3. Tissera, Hasitha A.; Jayamanne, Bernard D.W.; Raut, Rajendra; Janaki, Sakunthala M.D.; Tozan, Yesim; Samaraweera, Preshila C.; Liyanage, Prasad; Ghouse, Azhar; Rodrigo, Chaturaka; de Silva, Aravinda M.; Fernando, Sumadhya D. (April 2020). "Severe Dengue Epidemic, Sri Lanka, 2017". Emerging Infectious Diseases. 26 (4): 682–691. doi:10.3201/eid2604.190435. ISSN 1080-6040. PMC 7101108. PMID 32186490.
  4. "Dengue Fever Outbreak in Sri Lanka Kills Nearly 300 People". Time. Retrieved 2020-11-27.
  5. "Trends". www.epid.gov.lk. Retrieved 2020-11-27.
  6. "CDC - Neglected Tropical Diseases - Diseases". www.cdc.gov. 2022-03-07. Retrieved 2022-10-28.
  7. Ngwe Tun, Mya Myat; Muthugala, Rohitha; Nabeshima, Takeshi; Rajamanthri, Lakmali; Jayawardana, Dulani; Attanayake, Shanthi; Soe, Aung Min; Dumre, Shyam Prakash; Ando, Tsuyoshi; Hayasaka, Daisuke; Inoue, Shingo; Buerano, Corazon C.; Morita, Kouichi (2020-04-01). "Unusual, neurological and severe dengue manifestations during the outbreak in Sri Lanka, 2017". Journal of Clinical Virology. 125: 104304. doi:10.1016/j.jcv.2020.104304. ISSN 1386-6532.
  8. Ali, Shahid; Khan, Abdul Waheed; Taylor-Robinson, Andrew W.; Adnan, Muhammad; Malik, Shahana; Gul, Saba (June 2018). "The unprecedented magnitude of the 2017 dengue outbreak in Sri Lanka provides lessons for future mosquito-borne infection control and prevention". Infection, Disease & Health. 23 (2): 114–120. doi:10.1016/j.idh.2018.02.004.
  9. "What is a disaster? | IFRC". www.ifrc.org. Retrieved 2022-10-28.
  10. Stanaway, Jeffrey D; Shepard, Donald S; Undurraga, Eduardo A; Halasa, Yara A; Coffeng, Luc E; Brady, Oliver J; Hay, Simon I; Bedi, Neeraj; Bensenor, Isabela M; Castañeda-Orjuela, Carlos A; Chuang, Ting-Wu; Gibney, Katherine B; Memish, Ziad A; Rafay, Anwar; Ukwaja, Kingsley N (June 2016). "The global burden of dengue: an analysis from the Global Burden of Disease Study 2013". The Lancet Infectious Diseases. 16 (6): 712–723. doi:10.1016/S1473-3099(16)00026-8. PMC 5012511. PMID 26874619.
  11. "Trends". www.epid.gov.lk. Retrieved 2022-10-28.
  12. "Dengue and severe dengue". www.who.int. Retrieved 2022-10-28.
  13. Guha-Sapir, Debarati; van Panhuis, Willem Gijsbert (December 2009). "Health Impact of the 2004 Andaman Nicobar Earthquake and Tsunami in Indonesia". Prehospital and Disaster Medicine. 24 (6): 493–499. doi:10.1017/S1049023X00007391. ISSN 1049-023X.
  14. Tissera, H. A.; Samaraweera, P. C.; Jayamanne, B. D. W.; Janaki, M. D. S.; U Chulasiri, M. P. P.; Rodrigo, C.; Fernando, S. D. (February 2018). "Use of Bacillus thuringiensis israelensis in integrated vector control of Aedes sp. in Sri Lanka: a prospective controlled effectiveness study". Tropical Medicine & International Health. 23 (2): 229–235. doi:10.1111/tmi.13015.
  15. Ngwe Tun, Mya Myat; Muthugala, Rohitha; Rajamanthri, Lakmali; Nabeshima, Takeshi; Buerano, Corazon C.; Morita, Kouichi (2021-09-30). "Emergence of Genotype I of Dengue Virus Serotype 3 during a Severe Dengue Epidemic in Sri Lanka in 2017". Japanese Journal of Infectious Diseases. 74 (5): 443–449. doi:10.7883/yoken.JJID.2020.854. ISSN 1344-6304.
  16. "Gapminder Tools". www.gapminder.org. Retrieved 2022-10-28.
  17. WHO (2017). "World Bank and WHO: Half the world lacks access to essential health services, 100 million still pushed into extreme poverty because of health expenses". www.who.int. Retrieved 2022-10-28.
  18. "Sri Lanka - World Directory of Minorities & Indigenous Peoples". Minority Rights Group. 2019-06-19. Retrieved 2022-10-28.
  19. Kapila, Mukesh (2018). "Healthcare in Conflict Settings". World Innovation Summit for Health. Retrieved 2022-10-28.
  20. Xiao-Nong Zhou; Robert Bergquist; Remigio Olveda; Jürg Utzinger, eds. (2010). Advances in Parasitology: Important Helminth Infections in Southeast Asia: Diversity and Potential for Control and Elimination. Part A. London. ISBN 978-0-12-381956-7. OCLC 689053662.
  21. WHO (2022). "Vaccines and immunization: Dengue". www.who.int. Retrieved 2022-10-28.
  22. Root & Win (2022-08-09). "How Sri Lanka went from topping Lonely Planet's list to almost 30% hunger levels". The New Humanitarian. Retrieved 2022-10-28.
  23. Quiggin, John; Mallawaarachchi, Thilak. "How did Sri Lanka run out of money? 5 graphs that explain its economic crisis". The Conversation. Retrieved 2022-10-28.
  24. Bhatia, Surbhi; Bansal, Dhruvisha; Patil, Seema; Pandya, Sharnil; Ilyas, Qazi Mudassar; Imran, Sajida (2022). "A Retrospective Study of Climate Change Affecting Dengue: Evidences, Challenges and Future Directions". Frontiers in Public Health. 10. doi:10.3389/fpubh.2022.884645. ISSN 2296-2565. PMC 9197220. PMID 35712272.
  25. Yngve, Agneta; Margetts, Barrie; Hughes, Roger; Tseng, Marilyn (November 2009). "Food insecurity – not just about rural communities in Africa and Asia". Public Health Nutrition. 12 (11): 1971–1972. doi:10.1017/S1368980009991650. ISSN 1475-2727.
  26. "Current health expenditure (% of GDP) - Sri Lanka | Data". data.worldbank.org. Retrieved 2022-10-28.
  27. Pearson, Carl A. B.; Abbas, Kaja M.; Clifford, Samuel; Flasche, Stefan; Hladish, Thomas J. (August 2019). "Serostatus testing and dengue vaccine cost–benefit thresholds". Journal of The Royal Society Interface. 16 (157): 20190234. doi:10.1098/rsif.2019.0234. ISSN 1742-5689. PMC 6731500. PMID 31431184.
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