Dengue is a significant health issue especially in the coastal areas in Yemen. This study showed that not working, not using mosquito repellent, wearing short sleeves/pants, poor sanitation, outdoor trees and houses without window nets were the potential risk factors for DF outbreak in Taiz governorate.
Our result indicates that the highest peak of DF cases occurs in week 40, this possibly attributed to accumulation of water in the watercourse during the rainy season, that creates vector breeding sites. This finding shows that males were slightly more affected than females. This might be due to higher exposure of male as a result of spending more time outdoors than females and the females have protective clothes traditionally. Our result is similar to results of outbreaks investigation conducted in some Yemeni governorates (Al Hodeidah, Taiz and Hadramout), and in Pakistan [1, 11, 12, 13]. People with an age group < 30 years were more affected. This result might be due to people at this age being more active that makes them at risk of DF infections. These results are consistent with studies conducted in Al Hodeidah governorate, Vietnam, Hadramout governorate and India [1, 2, 12, 14].
Our result indicated that there isn’t a significant association between illiterate-basic educational level and getting DF infection. This result agrees with studies in India and Sudan [5, 15] and disagrees with previous study in Al Hodeidah governorate [1]. Not working people have more than twenty times the odds of getting DF infection compared with working people. This finding is similar to a study in Sudan that attributed to the fact that unemployment may pose a lifestyle behavior that provides a suitable habitat for the breeding of the mosquito vector, thus increasing the risk of mosquito contact [15]. Conversely, this finding is dissimilar to studies in India and Malaysia [5, 16].
Our findings revealed that there isn’t a significant association between not covering water containers and getting DF infection. Similar findings were reported in studies from Ethiopia and India [4, 17], but dissimilar to previous studies in Al Hodeidah governorate and Vietnam [1, 2].
Our result is in agreement with the fact that mosquito repellent is a protective measure against DF infection and showed that people who do not use mosquito repellents are at higher risk of getting infection with DF. These findings are consistent with studies in India, Kenya and Pakistan [17, 18, 19] and inconsistent with two studies in Ethiopia and others studies in Malaysia and China [3, 4, 16, 20].
Our result is similar to studies in Sudan, Malaysia and China [15, 16, 20] that indicate there isn’t a significant association between not using mosquito nets and the chance of getting DF infection. This finding might be due to the fact that mosquito nets are usually used at night, while Aedes aegypti mosquito is active during the day, especially in the early morning and late afternoon. However, this result is dissimilar to two studies in Ethiopia and one in Kenya [3, 4, 18].
Furthermore, our finding is similar to studies in Ethiopia [4] and Malaysia [16] reported that wearing long clothes is found to be protective and reduces the risk of DF infection, but dissimilar to study in Ethiopia [3].
The current investigation indicated that there is significant association between poor sanitation and DF infection. The people who live with poor sanitation have five times the odds of getting DF infection compared with people who have good sanitation. Our result is consistent with study in India [5], but inconsistent with studies in China and Brazil that reported that the lack of statistical significance attributable to improving the residential living environment, reducing mosquito breeding and coverage of sanitation services [20, 21].
Also there is a significant association between the presence of outdoor trees and getting DF infection. This might be due to the presence of outdoor trees that attract mosquitoes into human settlement. Conversely, a study in Vietnam reported that there isn’t a significant association between vegetation around living space and DF infection [2].
Additionally, there is significant association between those who are living in houses without window nets and getting DF infection. The individuals who live in houses without window nets are at risk of getting DF infection fifteen times the odds of getting DF infection compared with those who live in houses with window nets. This is possible to increase the exposure to mosquito biting. Our finding is consistent with studies in Malaysia and Pakistan [16, 19], but inconsistent with studies in Ethiopia and Kenya [4, 18].
As a result of limited financial resources, laboratory tests were not performed to ensure selection of the eligible controls. The wide confidence intervals in some variables is possibly attributed to small sample size of this study. However, these limitations should be taken into account when a similar study is conducted in the future.