Factors related to the presence of mosquito eggs trapped in ovitraps DHF-endemic areas in Kendari City, Indonesia

Background: Dengue hemorrhagic fever (DHF), one type of infectious disease caused by the dengue virus, is still becoming a public health problem in Indonesia. The high number of dengue cases in Indonesia, especially in Kendari City itself, is closely related to environmental conditions, especially when it is known that the city has entered the rainy season. Objective: This study aimed to identify and analyze the factors associated with the presence of mosquito eggs trapped in ovitraps DHF-endemic area in Kendari City, Indonesia. Methods: This study used an analytic observational approach with a cross-sectional design. The research sample in this study was 50 houses located in endemic areas of Kendari selected using simple random sampling. Data were collected by observation using a checklist sheet and direct observation in each room of the respondent's house based on lighting, temperature, humidity, and physical environmental conditions, as well as the presence of mosquito eggs or larvae trapped in the ovitrap. The analysis was carried out in two stages, namely univariate analysis and bivariate analysis using the Chi-Square test. Result: From 50 houses observed, 13 houses (26%) had the presence of mosquito eggs, 42 houses (84%) had bad air temperature, 19 houses (38%) had poor humidity, and 35 houses (70%) had a higher frequency. In addition, the temperature, lighting, and environmental conditions did not have a significant relationship with the presence of mosquito eggs in ovitraps in endemic areas of Kendari City, with p-values of 0.94, 0.52, and 0.39, respectively. In contrast, the humidity factor has a significant relationship with the presence of eggs with a p-value of 0.000. Conclusion: There was a significant relationship between humidity and the presence of mosquito eggs in ovitraps in endemic areas of Kendari City, Indonesia. It is recommended that residents increase Mosquito Nest Eradication (PSN) activities, perform selective abatization, and disseminate information about DHF through counseling or other activities conveyed through health workers with full support from community leaders and adjusted to the level of education of the local population.


Background
Dengue hemorrhagic fever (DHF) has become a public health problem in Indonesia (Tosepu, 2017). Dengue virus infection can be transmitted through mosquito bites (Yunus & Rosanty, 2016;Alhamda, 2017), and the types of mosquitoes that can be a source of transmission of dengue hemorrhagic fever are mosquitoes of the Aedes aegypti and Aedes albopictus species (Wertheim et al., 2012;. Dengue hemorrhagic fever is a seasonal disease that always appears every year. As if endless, DHF is a disease that infects many people in tropical and subtropical areas. Asia, especially Indonesia, ranks first in the number of dengue fever sufferers every year . Especially for Indonesia, high rainfall allows dengue cases to increase when the rainy season arrives . However, mosquito larvae are still able to breed in puddles so that they can still grow every year. This is coupled with environmental conditions and sanitation in many areas in Indonesia which are far from healthy (Widoyono, 2008;Siswanto et al., 2019).
Based on data from the Ministry of Health of the Republic of Indonesia in 2020, the total cases of DHF in Indonesia reached 95,893 cases, and 661 people died from the disease. The total cases of DHF were spread across 472 districts/cities in 34 provinces, with deaths from dengue hemorrhagic fever reported from 219 districts/cities. In November 2020, there were 51 additional cases of dengue fever and one additional death report due to dengue hemorrhagic fever. In addition, 73.35 percent or 377 districts/cities have reached an Incident Rate of less than 49 per 100 thousand inhabitants (Ministry of Health Republic of Indonesia, 2020).
The number of dengue cases reported at the Kendari City Health Office, Southeast Sulawesi, Indonesia, until mid-June 2020 reached 764, with eight of them dead. Distribution of patients who died from dengue fever in Kendari City, Bau-Bau City, and Konawe Regency. The cases were spread in 15 regencies and cities, and the most cases were in Kendari City, around 291 cases, and the lowest cases were in the Buton district. There are several endemic areas for the spread of the dengue virus, such as Poasia subdistrict, Wua wua sub-district, and Puuwatu, where these areas from year to year have always been the largest contributor to DHF patients in Kendari City, Indonesia (Dinas Kesehatan Kota Kendari, 2020).
Preliminary studies carried out by research still found several mosquito larvae in several residents' homes, and the survey results found the larvae-free rate (ABJ) was at least 60%. The presence of larvae in an area is known by the indicator of the larva-free rate. ABJ is the percentage of houses or public places where larvae are not found. Low ABJ is influenced by several factors. The behavior of the population in terms of storing water for daily needs is not only in one place, and rarely cleaning water reservoirs allows the Aedes aegypti mosquito to have more opportunities to lay eggs (Sitorus & Ambarita, 2019). According to Hasyimi and Soekirno (2019), the most common Aedes aegypti larvae or pupae found in household landfills are household landfills made of metal. The type of household landfill that most commonly found larvae or pupae of Aedes aegypti was the jar type landfill. There are three types of TPA found positive for Aedes aegypti larvae inside or outside the house, namely drums, bathtubs, and plastic buckets (Sitorus & Ambarita, 2019).
The high number of dengue cases in Indonesia, especially in Kendari City, is closely related to environmental conditions, especially since Kendari City has entered the rainy season. There are still many people who do not understand the environmental conditions that can trigger the spread of dengue fever. Environmental conditions are conditions that can affect the development of Aedes aegypti mosquito larvae. DHF vector breeding and resting places such as containers filled with water, humidity, lighting, and air temperature can be a big threat to the spread of DHF disease (Anwar & Rahmat, 2015). Therefore, this study aimed to analyze the factors associated with the presence of mosquito eggs trapped in the ovitrap DHF-endemic area in Kendari City, Indonesia.

Study Design, Setting, and Subjects
This study uses an analytical observational approach with a cross-sectional design. This research was conducted in July 2019 involving 58 households in the endemic area selected using simple random sampling.

Instrument
Data were collected by observing using a checklist sheet and direct observation in each room of the respondent's house based on lighting, temperature, humidity, and physical environmental conditions, as well as the presence of mosquito eggs or larvae trapped in the ovitrap. The observation sheet was adopted from previous research (Panjaitan, 2014)

Data Analysis
Data were analyzed using univariate analysis to describe the distribution of respondents and each variable. Furthermore, bivariate analysis was carried out to test the hypothesis of the relationship between the independent variable and the dependent variable, using computer software with SPSS version 25 with Chi-square test (significance level pvalue 0.05 or 95% confidence level).

Ethical Consideration
This study was approved by the Ethical Clearance Committee of Poltekkes Kemenkes Kendari, Indonesia (Ref number: UT.01.01/6/6021/ 2019). Consent was obtained from the administrative bodies of the health facility and the participants. Table 1 shows that there were more houses with bad air temperature, namely 42 houses (84%), compared to houses with good air temperature, namely eight houses (16%). The house with good humidity had a higher distribution of 31 houses (62%) than the house with bad humidity at 19 houses (38%). Houses with dim lighting had a higher frequency of 35 houses (70%) than 15 houses with bright lighting (30%). In addition, the condition of the physical environment of houses that met the requirements was higher, 38 houses (76%), compared to houses that did not meet the requirements, 12 houses (24%). The results of the presence of eggs in the ovitrap installed in the house were found to have mosquito eggs in 13 houses (26%), while 37 houses did not find any mosquito eggs (74%).  Table 2 shows that the houses with a temperature at risk for the development of mosquito eggs were more in the houses with a bad temperature of 11 houses (75%) than the houses with a good temperature of 2 houses (25%). The Chi-Square test results obtained a p-value of 0.944, which indicates that there was no significant relationship between temperature and the presence of mosquito eggs. Table 3 shows that houses that have the humidity at risk for the development of mosquito eggs were more in houses with bad humidity as many as 13 houses (68.42%), while houses that had good humidity had no development of mosquito eggs. The Chi-Square results obtained a p-value of 0.000, indicating a significant relationship between humidity and the presence of mosquito eggs.  Table 4 shows that the houses that have lighting at risk for the development of mosquito eggs were more in houses with low lighting as many as ten houses (28.57%), while houses with bright lighting were found in 3 houses that have the presence of mosquito eggs (20%). Also, there was no significant relationship between lighting and the presence of mosquito eggs, with a p-value of 0.527.

Physical and Mosquito Eggs Presence
Based on Table 5, it is found that the houses that have physical environmental conditions at risk for the development of mosquito eggs were more in houses with a physical environment that met the requirements as many as 11 houses (28.95%) while houses with a physical environment that did not meet the requirements were only found two houses, which had the presence of mosquito eggs (16.67%). In addition, there was no significant relationship between physical environmental conditions and the presence of mosquito eggs.

Discussion
The results of observations of poor house air temperatures were more at risk of developing mosquito eggs than good house temperatures, but based on the results of the Chi-Square test, there was no significant relationship between house air temperature and the presence of mosquito eggs in ovitraps in endemic areas of Kendari City (p-value 0.944). This phenomenon shows that good or bad house temperature conditions did not rule out the possibility of the development of mosquito eggs and may be exposed to dengue disease. The results of this study were in line with Yudhastuti and Vidiyani (2005) research on the relationship between environmental conditions, containers, and community behavior with the presence of Aedes aegypti mosquito larvae in dengue hemorrhagic fever endemic areas, Surabaya, Indonesia, that there was no significant relationship between air temperature and the presence of Aedes aegypti mosquito larvae in the Wonokusumo Village (p-value 0.591). Another study by Rahmayanti et al. (2016) regarding the relationship between physical environmental factors of the house and the incidence of dengue fever in Semarang City, Indonesia, also showed that there was no relationship between temperature and the incidence of dengue fever with a p-value of 0.608.
The results of house lighting observations found that the distance of the respondent's house, which was quite close, affected the intensity of light that could enter the house, and there were still many trees around the house, so that the lighting was less than optimal. This provides an opportunity for mosquitoes because a place with minimal light will be used as a place to rest. However, based on the results of the Chi-Square test, it was found that there was no relationship between lighting and the presence of eggs (p-value 0.527). The results of this study were not in line with the research of Werdinigsih et al. (2017) on the relationship between physical environmental conditions and the presence of mosquito larvae that there was a relationship between lighting conditions and the presence of mosquito larvae with a p-value of 0.008. The absence of a significant relationship between lighting and the presence of eggs in this study is because most residents often open doors or windows in the morning and afternoon so that there is still sunlight coming in.
In addition, the findings of this study showed that there was no significant relationship between the physical environment of the house and the presence of mosquito eggs in the ovitrap in the endemic area of Kendari City (p-value 0.398). This study was in line with research conducted by Nugroho (2009) on factors related to the presence of Aedes aegypti larvae that there was no relationship between waste and the presence of Aedes aegypti larvae (p-value 0.504). The results of observations in this study of physical environmental conditions such as water reservoirs (bathtubs & pots), solid waste disposal sites have mostly met the requirements, and only a few were found around the respondent's house, such as solid waste in the form of used bottles and used cans. In addition, the existence of types of water reservoirs both inside and outside the respondent's house has a high risk as a breeding ground for the Aedes aegypti mosquito, but only two houses out of a total of 50 houses do not meet the requirements for physical environmental conditions and most houses, or the majority of houses meet the conditions of the physical environment.
The results of the observation of the humidity factor found that under humidity, the risk for the development of mosquito eggs was more in homes that had bad humidity as many as 13 houses (68.42%) while houses with good humidity did not find the development of mosquito eggs. In addition, there is a significant relationship between humidity and the presence of eggs in mosquitoes in ovitraps in endemic areas of Kendari city (p-value 0.000). The results of this study are in line with Yudhastuti and Vidiyani (2005) research on the relationship between environmental conditions, containers, and community behavior with the presence of Aedes aegypti mosquito larvae in dengue hemorrhagic fever endemic areas, Surabaya, that there is a significant relationship between air humidity and the presence of Aedes aegypti mosquito larvae in Wonokusumo Village (p-value 0.000).
Humidity ranges from 60%-80% is the optimal humidity to help the embryonication process and mosquito larvae resistance. At a humidity of less than 60%, the lifespan of a mosquito will be short because it will affect the mosquito's respiratory system so that if it is in low humidity, it will cause evaporation of the mosquito's body (Wijirahayu & Sukesi, 2019).

Conclusion
The factors of temperature, lighting, and environmental conditions were not related to the presence of eggs in ovitraps DHF-endemic area in Kendari City, Indonesia, but humidity factors related to the presence of eggs in ovitraps. However, further research is needed, especially with a larger population and sample coverage. It is also recommended for residents to increase Mosquito Nest Eradication (PSN) activities, perform selective abatization or keep larvae-eating fish in places that are difficult to clean to eradicate larvae and do fogging to kill mosquito populations and dissemination of information about DHF through counseling or other activities should be conveyed through health workers with full support from community leaders and adjusted to the level of education of the local population. In addition, the threat of dengue will increase when people begin to enter a new life order or new normal. Buildings or office buildings that have been inactive for a long time during the quarantine period (pandemic  for the past few months have the potential to become soft places for Aedes aegypti mosquitoes to breed. For this reason, it is recommended that the Mosquito Nest Eradication (PSN) be carried out as well as possible in order to avoid the transmission of dengue fever when the community is busy entering the new normal period.

Declaration of Conflicting Interest
The authors declare no conflict of interest.

Funding
None.