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
I.
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