INTRODUCTION
Dengue infection is one of the most common arbo-viral infection worldwide and has caused a huge medical and economic burden [ 1, 2 ]. In Indonesia, Dengue fever( DF) outbreaks is the largest in ASEAN region [ 3 ]. In relation to climate change, incidence of DF is proven to be significantly correlated to temperature, humidity, and rain precipitation in various region [ 4-8 ]. An increase in those parameters causes an increase in mosquito’ s breeding site and, consequently, mosquito population and DF incidence.
Sampang is one of the region which have been consistently hit by an epidemic of Dengue despite the strategies that have been implemented to prevent and eradicate DF in Sampang. Temperature in Sampang is consistent all year round at 27.1 o C. Rain precipitation fluctuates, peaking at December and hitting the bottom on August. A better understanding about the relation between Sampang’ s climate and DF incidence will be beneficial to reduce morbidity and mortality rate. [ 9 ]
Figure 3. DF and Death Incidence Progression Year by Year 700
DF Incidence
600 500 400 300 200 100
0 |
2012 |
2013 |
2014 |
2015 |
DF Incidence |
271 |
494 |
209 |
639 |
Death |
3 |
4 |
2 |
11 |
|
|
DF Incidence |
Death |
|
Figure 4 DF Incidence Comparison Between Month 300
12 10 8 6 4 2 0
Death Incidence
OBJECTIVES
As a pilot project, this study aims to analyze descriptively the relationship of DF incidence and death rate towards climate change, especially on rainfall and temperature at Sampang regency. This study can be used as a basis for future policy in anticipating dengue fever in Sampang and also Indonesia.
MATERIALS & METHODS
Retrospective observational study was conducted. Secondary data were retrieved from all government health facilities in Sampang regency. Two specific parameters were investigated:( 1) DF incidences and( 2) death rate. Data regarding climate and geographical characteristics were retrieved from Statistics Indonesia and Indonesian Agency for Meteorology, Climatology, and Geophysics. These data were analyzed descriptively and presented in charts and figures to answer the main problem in this study.
CONCEPTUAL FRAMEWORK
Humidity ↗ Temperature ↗ Rainfall Index ↗ and weather seasons
Increase of mosquitoes population and dengue transmission
Increase of yearly cumulative DF incidence
RESULTS
Figure 2. DF and Death Incidence Monthly Cumulative Patterns 800
DF Incidence
700 600 500 400 300 200 100
0 |
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
oct |
Nov |
Dec |
DF Incidence |
692 |
488 |
297 |
209 |
115 |
49 |
50 |
38 |
34 |
52 |
61 |
64 |
Death Incidence |
6 |
8 |
6 |
1 |
1 |
0 |
0 |
0 |
0 |
1 |
2 |
0 |
DF Incidence
Monthly variations in mosquitoes population and dengue transmission
Death Incidence
Monthly variations of dengue fever incidence
Dengue Epidemiology and Surveillance in Sampang regency
REFERENCES 1. Anders KL, Nguyet NM, Chau NV, Hung NT, Thuy TT, Lienle B, et al. EpidemiologicalfactorsassociatedwithdengueshocksyndromeandmortalityinhospitalizeddenguepatientsinHoChi Minh City, Vietnam. Am J Trop Med Hyg. 2011: 84:127-34. 2. Coudeville L, Shepard DS, Zambrano B, Dayan G. Dengue economic burden in the Americas: estimates from dengue illness. Am J Trop Med Hyg 2009: 81:127 – 127. 3. Kementerian Kesehatan RI. Buletin Jendela Epidemiologi. Jakarta: Pusat Data dan Surveilans Epidemiologi Kementerian Kesehatan RI; 2010. 4. Carrington LB and Simmons CP. Human to mosquito transmission of dengue viruses. Frontiers in Immunology. 2014; 5: 1-8. 5. Wiwanitkit V. An observation on correlation between rainfall and the prevalence of clinical cases of dengue in Thailand. Journal of Vector Borne Disease. 2006: 43, 73-76 6. Lu L, Lin H, Tian L, Yang W, Sun J, Liu Q. Time series analysis of dengue fever and weather in Guangzhou, China. BMC Public Health. 2009: 9, 395
9 8 7 6 5 4 3 2 1 0
Death Rate
250 200 150 100 50 0
Jan Feb Mar Apr May Jun Jul Aug Sep oct Nov Dec
DISCUSSIONS
1. Monthly cumulative pattern & monthly rainfall index in Sampang regency( Fig 1 dan 2)
From figure 1, we can see that the rainy season in Sampang is between October-March with its peak on December. Dry season usually start around April to September with its peak on August. Temperature are consistent all year round at 27.1 O C. Average rainfall in Sampang is around 1,415 mm with the highest precipitation falls in December with an average of 239mm [ 9 ].
The peak of rain precipitation( December) and the peak of DF incidence( January) had 1 month delay. These findings were consistent with the findings on another studies in Guangzhou, studies in Thailand, and the theories proposed by Carrington [ 4 ] that there will be ± 24-30 days of time gap after the rainy season begins before the incidence of DF rises. These gap is caused by the total of time for mosquito life cycle, dengue virus incubation in Aedes mosquito, and the dengue incubation period in human body [ 4-6 ].
Figure 2 also showed that the peak of DF incidence and the peak of death rate also had 1 month delay. This finding also supported by the study in Malaysia which reported that 38.9 % of dengue mortality cases happened with a month gap after the surged incidence of suspected dengue cases from the same area in Malaysia [ 10 ].
2. Yearly cumulative pattern of DF incidence( Figure 3)
2012 2013 2014 2015 2016
From figure 3, we can observe that there is an annual increase of DF incidence except on 2014 where the incidence dropped for approximately 50 %. The increase might be caused by the increase of temperature in Indonesia( 0.3 o Cannually), aspredictedbyHulmeandSheard [ 11 ], andtheshift in rainfall precipitation index in various regions in Indonesia [ 12 ]. More climate data specifically on Sampang is needed to ascertain the cause of the increment. These trend were also parallel with other studies conducted in tropical climate( Malaysia) and subtropical climate( Japan) with a gradual increase of DF incidence year to year [ 13, 14 ]
3. Monthly pattern of DF incidence & monthly rainfall index in Sampang regency( Fig 4 & 1)
Data from figure 4 showed that although the number of DF incidence differs from year to year, but the pattern of monthly DF incidence has not changed in the last 5 years. The highest peak of DF incidence always happens on January which would then decrease gradually until reaching its lowest incidence around August and September, markings the end of dry season, and start to increase slowly on transition months between dry & rainy season( October & November)( Fig 1)
CONCLUSIONS
We found that DF incidence followed the pattern of rainfall index and the climate in the locals region. Higher precipitation and rainfall promotes the increase of DF incidence within a month gap delay and vice versa.
Our study provides evidence on the relationship between weather and climate in relation to DF incidence and death rate in Sampang regency. Further study and information about these topics in Indonesia would be beneficial to support our findings and give better understanding of dengue epidemiology in Indonesia.
7. Hii YL, Zhu G, Ng N, Ng LC, Rocklov J. Forecast of Dengue Incidence Using Temperature and Rainfall. PLOS Neglected Tropical Disease. 2012: 6( 11), 1-9 8. Patz JA, Martens WJM, Focks DA, Jetten TH. Dengue Fever Epidemic Potential as Projected by General Circulation Models of Global Climate Change. Environmental Health Perspectives. 1998: 106( 3), 147-153 9. Climate Data. Iklim: Grafik iklim – Sampang, grafis suhu, tabel iklim – Climate-Data. org [ Internet ]. Climate Data 10. Woon YL, Hor CP, Hussin N, Zakaria A, Goh PP, Cheah WK. A two-year review on epidemiology and clinical characteristics of dengue deaths in Malaysia, 2013-2014. 11. Hulme M, Sheard N. Climate change scenarios for Indonesia. Norwich: Climatic research unit. 12. Boer R, Faqih A. Current and future rainfall variability in Indonesia. Report from AIACC project no. AS21. Washington DC: International START Secretariat. 13. Mudin RN. Dengue Incidence and the Prevention and Control Program in Malaysia. The International Medical Journal Malaysia. 2015: 14( 1), 5-9. 14. Fukusumi M, Arashiro T, Arima Y, Matsui T, Shimada T, Kinoshita H, Arashiro A, Takasaki T, Sunagawa T, Oishi K. Dengue Sentinel Traveler Surveillance: Monthly and Yearly Notification Trends among Japanese Travelers, 2006 – 2014. PLOS Neglected Tropical Disease. 2016: 10( 8), 1-14