In , this number slightly decreased to cases. In , however, a total of cases were notified 0. Therefore, it is important to point out that the number of cases reported in was atypical compared with the previous years, and even , when the number of notified cases rose to The highest incidence rate per municipality was registered in Diadema, with According to the data supplied by the CVE, the months of January, February, March, April and May from to were the ones with the highest number of notified cases.
As a result, an analysis of climatic and environmental factors during those months was carried out so that a possible relation between these variables and a higher proliferation and notification of dengue cases could be established.
Figure 1 presents an extremely close relation between temperature values and the notified dengue cases. It can be observed that temperature peaks coincided with epidemic peaks between the months of January and May. Nevertheless, while this relation is quite clear, there was no statistically significant association between them. As for humidity, this variable had a positive correlation 0.
In other words, whenever humidity rates reached their highest values, there was an increase in number of registered cases in the area. Interestingly, PM10 had a negative Pearson correlation -0, , showing that lower PM10 values coincided with a higher number of dengue cases. Air pollution could therefore be the reason for reported dengue cases.
In scientific terms, there is a relation between temperature and humidity, so that relative humidity can be defined as the ratio of the amount of water vapor in the air at a specific temperature to the maximum amount that the air could hold at that temperature.
At higher temperatures the air may contain more water vapor than the same volume of air at lower temperatures. Impact of air temperature on relative humidity: a study. Architecture - Time Space and People. Our findings show that the months presenting temperature and humidity peaks, namely January, February, March, April and May, also had more notifications of dengue cases.
The year emerges as the year with the highest number of notified cases. This increasingly common scenario, where winter is no longer a cold and dry season, is a climate change resulting from global warming.
The most industrialized municipalities are the ones with the highest rates of notified dengue cases, which can be explained by the possibility of many cases being imported. Despite the difficulty in identifying whether the disease is autochthonous or imported, one must consider that these individuals may be infected in the municipality where they live but seek assistance in the municipality where they work, if medical care is more convenient or easily accessed in the latter.
These climate abiotic factors have shown an association with the incidence and prevalence of dengue. Many studies have revealed the important role of rainfall in the renewal and oscillations of puddles, conditions that favor egg hatching and the incubation period of the mosquito.
It is thus clear that temperature and rainfall levels in the months of January, February and March throughout the years were favorable for the development of the virus and that these factors may have contributed to a higher incidence of dengue cases. Accordingly, dengue cases appear after weeks of peak temperature and rainfall, a time during which the mosquito can develop and contaminate the population.
The ocurrence of dengue and weather changes in Brazil: a systematic review. Another fact to be considered is the time it takes for each individual to show symptoms of the disease, and, as a result, the time that elapses until these individuals search for assistance at a medical care unit. The greatest number of dengue cases is expected to be reported in the months of February, March, April and May.
Concerning particulate matters, a decrease in the concentration of PM10 is observed from January to May, a critical period when cases are registered most often in the region. Although not confirmed by any study to date, the presence of air pollutants apparently interferes with the life cycle of the Aedes aegypti mosquito.
The relation between health and environment can be clearly seen through the analysis of epidemiological characteristics in areas close to contamination sources and through the identification of adverse environmental factors that are harmful to health.
Low environmental temperatures will also prolong the EIP of dengue virus Goindin et al. The average temperature in Sleman District ranges from Lower temperatures occur in highland areas during the dry season June-July. Higher temperatures occur in lowland areas at the beginning of the rainy season October and the end of the rainy season April. More in-depth research is needed to discover the effects of precipitation on dengue cases more precisely.
The results show that the temperature of the environment had no significant effect on dengue incident Table 2. This is probably because the temperature factor used for the analysis is the monthly average, so the daily temperature fluctuations are not visible. Day and night temperature differences are quite high during the dry season June-November in Indonesia. Kesetyaningsih article submitted for publication states that the minimum-maximum temperature difference affects the incidence of DHF in Sleman district.
The higher the minimum-maximum temperature difference is, the lower the incidence of DHF. However, if Aedes mosquitoes adapt to high environmental temperature fluctuations, outbreak may occur because mosquitoes survive, while extrinsic incubation of the virus becomes faster. Pakem is a sporadic dengue area Figure 2 , where dengue cases are not affected by climate factors Table 2.
It should be realized that Pakem can be an endemic area if the physical development is not followed by adequate community knowledge about dengue disease. Physical development can increase temperatures Tokairin, and increase the number of breeding places Saleeza et al.
In Table 3 , it appears that Only 7. Pearson correlation test shows a positive correlation p 0. The greater the percentage of the building area in the buffer area is, the more the dengue cases are. However, data suggest that dengue cases always occur in buffer areas that have tree vegetation.
In this study, the calculated vegetation is trees, not grass or rice field. This is based on the knowledge that the existence of trees is relatively the same throughout the year and impacts on the maintenance of local humidity microenvironment Wong and Peck, ; Tahir and Yousif, a; Obi, and decreases the wind speed in the area around trees Leenders et al. Aedes aegypti chooses shading places Prado et al. Several studies have shown that the type of land cover is related to the density of mosquitoes or dengue cases.
Sarfraz et al. Vanwambeke et al. Extensive settlements affect dengue cases in urban areas Li et al. The presence of vegetation around the dengue patient dwellings in this study indicates that dengue in Sleman District belongs to the sub-urban type category. The trees around the house become a factor to consider in controlling dengue disease in Sleman District. Sleman region has a considerable different height among one area with others which affects the spread of dengue. Northern Sleman is a highland, which is along the slopes of Mount Merapi.
Some reports indicate that the maximum elevation of Aedes sp. In Sumatra, Aedes sp. Anwar et al. In Mexico City, Aedes aegypti was discovered up to 1, m a.
Fuentes et al. No data of the highest location has been found by Aedes in Sleman. Dengue cases in Sleman occurred up to m a. Figure 9. Pearson correlation test shows that there is a negative correlation between the height of the incidence of dengue with moderate strength p 0.
This indicates that the higher the area, the lower the dengue case. According to Andrian et al. According to Brady et al. Dengue disease is multifactorial. There are many factors that influence the incident of dengue case among others from the environmental factor, human being as host or virus as agent.
The results of this study indicate that none of the environmental factors studied are prominent and closely related to dengue cases in Sleman. Land cover and elevation factors have been shown to be related to dengue cases even though they have only weak strength.
Humidity and rainfall factors affect dengue cases in different areas, with weak to moderate strength. This shows that the dengue incidence is local. The limitations of climate data, especially temperatures and humidity, which only originate in two observation posts, are likely to cause less accurate data, especially in areas that are beyond the scope of observation.
With respect to climate data that is sometimes incomplete, so data interpolation should be done which cause the data to be less accurate. The correlation between dengue incidents with environmental factors and the possible influence of the distance factor indicate that the need for spatial analysis in revealing the role of environmental factors to be more representative. The spatial pattern of dengue in Sleman is clustered. No environmental factors are closely related to dengue incidence.
The most prominent environmental factor associated with dengue cases is humidity, with moderate strength. Land cover, elevation, and rainfall have weak correlation with dengue cases. Temperature does not affect dengue cases. All climate parameters do not affect dengue cases in sporadic areas. Conflict of Interest: There is no conflict of interest among the authors related to the publication of this manuscript. National Center for Biotechnology Information , U.
Afr J Infect Dis. Published online Mar 7. Author information Article notes Copyright and License information Disclaimer. This article has been cited by other articles in PMC. Abstract Background: Dengue is a disease related to the environment that spreads rapidly. Materials and methods: This ecological study was conducted on five sub-districts selected based on the trend of the incidence.
Results: There were 1. Conclusion: It is concluded that dengue in Sleman is clustered and associated with the environment parameter, even though it does not have close correlation. Keywords: dengue, climate, land cover, elevation, spatial patter. Open in a separate window. Figure 1. Sleman district is located in north part of Yogyakarta, Java Island of Indonesia.
Data collection Monthly data of dengue cases in become the secondary data gained from Health Department of Sleman District. Results Dengue Case There are 1, dengue cases in five sub-districts of the research location during periods.
The DHF cases trend in periods of Spatial pattern: Geographical distribution of dengue during — is shown in Figure 3. The spreading of DHF points in the periods of — in study site. Year Z-score P value , 0, , 0, , 0, -6, 0, -7, 0, , 0, Climate—dengue incidence Sleman district has a wet tropical climate in which the rainy season is between November to April and the dry season is between May to October. The distribution of DHF cases year by altitude in study site. Discussion Spatial pattern The spatial pattern test using Average Nearest Neighbours shows that the incidence of dengue in five sub-districts in the study sites has a clustering pattern Table 1.
Climate-dengue incidence The result of multiple regression test of monthly climate data of shows that humidity affects the dengue case in Gamping with p 0. Land cover-dengue incidence In Table 3 , it appears that Elevation-dengue incidence Sleman region has a considerable different height among one area with others which affects the spread of dengue.
Conclusion The spatial pattern of dengue in Sleman is clustered. Footnotes Conflict of Interest: There is no conflict of interest among the authors related to the publication of this manuscript.
References 1. Andrian Supriadi, Marpaung P. Online Journal of Agroecotechnology June Controlling Dengue Outbreaks. Because there is currently no effective vaccine against dengue and no specific treatment for the disease, controlling and preventing dengue fever outbreaks are essential steps for keeping people healthy.
What methods are presently used or being developed to control dengue outbreaks in regions where the threat of dengue is high? Environmental Management of Dengue Mosquito Populations. Figure 1: Aedes aegypti container habitats. Aedes aegypti lay their eggs in containers such as bottles, tires, fountains, barrels, and pots. Personal Actions to Reduce Contact with Mosquitoes.
People can reduce the risk of mosquitoes entering their homes by using window and door screens or by keeping their doors and windows closed and using air conditioning to keep their homes cool.
Aedes aegypti typically bite people during the day, so wearing long pants and long-sleeved shirts can reduce mosquito bites when spending time outdoors. In addition, mosquito repellents can be applied to exposed skin and clothing to lower the risk of mosquito bites. Sleeping under a mosquito net can also provide protection from being bitten, particularly in areas where people rest in the afternoon or in houses with infants.
What about other methods of reducing mosquito populations? Figure 2: Ovitrap. An ovitrap is a mosquito trap. It is a black, cylindrical container filled with water that appears to be an ideal location for a female Aedes aegypti to lay eggs.
The female lays her eggs on the cardboard paddles. The eggs then fall through the mesh into the water, where the larvae hatch and develop into pupas. When the adult mosquitoes emerge, they are trapped beneath the mesh and are unable to escape from the ovitrap. Chemical Control of Dengue Mosquitoes. Chemical control can be effective in controlling mosquito populations. For instance, insecticides can be used to kill mosquito larvae or adult mosquitoes.
Can insecticides be widely and routinely used? The use of insecticides is recommended in emergency situations during dengue epidemics or when there is evidence that an epidemic is emerging. On a regular basis, however, sustainable, coordinated, community-based environmental approaches are favored over chemical methods for controlling mosquitoes, and limited reliance on these chemicals is preferred.
Why are environmental management approaches favored? One reason is that mosquitoes can develop resistance to insecticides. In addition, insecticides are expensive, and high doses can be toxic to humans and other species. Therefore, it is best to be cautious about applying these chemicals. Biological Control of Dengue Mosquitoes. Figure 3: Mosquitofish eating mosquito larvae. Mosquitofish Gambusia affinis can be placed in decorative ponds and other large container habitats to prey on mosquito larvae and effectively prevent mosquito development.
In the absence of an effective vaccine that protects humans from dengue, limiting contact between people and vectors is the most effective way to prevent dengue infections. Environmental management approaches involve eliminating the container habitats in which Aedes aegypti lay their eggs.
Chemical control involves the use of insecticides to kill immature or adult mosquitoes. New chemical, biological, and genetic approaches are also being developed and may provide promising alternatives to control mosquito populations and prevent dengue infections.
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