Retrospective Time Series Analysis of Dengue Fever Incidence and Death Case in Relation to Climate and Weather between January 2012 until May 2016 at Sampang Regency , East Java , Indonesia
Julius Albert Sugianto *, Michael Jonatan ** * Universitas Airlangga – (+ 62 ) 89675844351 ; julius _ albert14 @ yahoo . com ** Universitas Airlangga – (+ 62 ) 82141612191 ; michaeljonatan1996 @ gmail . com
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Introduction Dengue Infection
Dengue infection is one of the most common arbo-viral infection worldwide and the medical and economic buden it causes is large [ 1 , 2 ]. Dengue infection is caused by dengue virus ( DENV ) that is transmitted mainly by Aedes aegypti and some by Aedes albopictus mosquitoes . Dengue virus is a single positive stranded RNA virus of the family Flaviviridae ; genus Flavivirus . Up until 2015 , there are 5 serotypes of DENV that has been found ( DENV-1 , DENV-2 , DENV-3 , DENV- 4 , and DENV-5 ) [ 3 ]. The discovery of DENV-5 was found during in a 2007 dengue outbreak from a 37 year old farmer in Malaysia and DENV-5 is the only virus belongs to the sylvatic cycle , meaning that DENV-5 circulates primarily in non-human primates . The other four serotypes ( DENV-1 , DENV-2 , DENV-3 , DENV-4 ) are closely related and share approximately 65 % of their genotype , and these serotype is transmitted to human form , not sylvatic form like DENV-5 [ 3 , 4 ].
The incidence of dengue fever ( DF ) and dengue hemorrhagic fever ( DHF ) has increased in recent decades . While the actual numbers of dengue infection and dengue fever are underreported , it is estimated that annually there are 3.9 billion people at risk of infection , with a reported case more than 100 million , and 25,000 deaths annually , mostly in tropical and sub-tropical countries , such as Indonesia , Myanmar , Sri Lanka , India , and Thailand [ 5 , 6 ].
WHO in ( 2009 ) reported that more than 70 % of the population at risk for dengue worldwide live in South-East Asia and Western Pacific region . These regions bear approximately 75 % of the current global disease burden due to dengue [ 6 ].
According to Indonesia ’ s health ministry , over the last several years , the number of dengue fever outbreaks in Indonesia was the largest in ASEAN region , followed by India and Myanmar [ 7 ]. Health ministry ( 2010 ) stated that there were a significant increase of DHF cases from 58 cases in 1968 ( incidence rate 0.05 per 100,000 population ) to 158,192 cases in 2009 ( incidence rate 68.22 per 100,000 population ). These increment were thought to be an indirect effect of high mobility , climate change , and population density [ 7 ].
Dengue Infection and Climate Change
Various theories regarding the cause of the rise in DF incidence are available . Carrington LB [ 8 ] neatly summarized the theories in his review . In his review , he wrote that there are two main important points to be assessed when studying the virulence of DF : Human factors influencing transmission and mosquito susceptibility to infection . The human factors are the viral titer in human plasma , duration of human infectiousness , and symptomatic vs asymptomatic infections . Meanwhile , mosquito susceptibility to infection are affected by the relative vector competence , virus concentration in the blood meal , environmental temperature , humidity , mosquito ’ s genotype and blood feeding behavior [ 8 ]. The factors mentioned above focuses on internal factors of mosquitoes and humans . In relation to weather and climate change , this article would focus more on the environmental factors that would affect the mosquito ’ s life cycle and , consequently , its capability to infect humans which are temperature , humidity , and rainfall .
Aside from the factors mentioned by Carrington LB [ 8 ], other authors studying the relation of DF incidence and weather also see temperature and humidity as an important parameter but also highlighted the effect of rainfall [ 8-13 ]. Rainfall causes massive stagnant water places , such as in puddle , garbage dumps , open perimeter dumps , and ground depression which would act as the reservoirs and the potential breeding sites of Aedes mosquito . Significant association between