An Ecological Context Toward Understanding Dengue Disease Dynamics in Urban Cities: A Case Study in Metropolitan Manila, Philippines

Carvajal, Thaddeus M.; Ho, Howell T.; Hernandez, Lara Fides T.; Viacrusis, Katherine M.; Amalin, Divina; Watanabe, Kozo

doi:10.1007/978-981-13-2526-7_10

Cited by 7 publications

(7 citation statements)

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“…Sabah is rapidly gaining economic progress with the state GDP increasing from 2.7% in 2011 to 8.2% in 2017 [34] and experiencing rapid urbanization in the form of large physical growth of urban areas along with environmental changes leading to economic development [35]. The dynamic movement of people and the change in land use are mediators for human-mosquito interactions, which indirectly expands mosquito habitats [36]. These figures interestingly reflect the trend of increasing dengue cases from 2013 to 2018 in Sabah, indicating perhaps a correlation between both trends.…”

Section: Discussionmentioning

confidence: 99%

The east coast districts are the possible epicenter of severe dengue in Sabah

Kaur¹,

Rahim²,

Jaimin³

et al. 2020

J Physiol Anthropol

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Background: Malaysia recorded the highest number of dengue cases between 2014 and 2017. There are 13 states and three federal territories in Malaysia, and each area varies in their prevalence of dengue. Sabah is one of the states situated in Borneo, Malaysia. Although dengue has been increasing for the last several years, no study was being done to understand the burden and serotype distribution of the dengue virus (DENV) in Sabah. Therefore, the present study was carried out to understand the epidemiology of the dengue infection and the factors responsible for severe dengue in Sabah. Methods: Data on dengue infection were extracted from the dengue database of the state of Sabah from 2013 through 2018. DENV NS-1-positive serum samples from multiple sites throughout Sabah were sent to the state public health laboratory, Kota Kinabalu Public Health Laboratory, for serotype determination. The analysis of factors associated with severe dengue was determined from the data of 2018 only. Results: In 2013, there were 724 dengue cases; however, from 2014, dengue cases increased exponentially and resulted in 3423 cases in 2018. Increasing dengue cases also led to increased dengue mortality. The number of dengue deaths in 2013 was only five which then gradually increased, and in 2018, 29 patients died. This is an increase of 580% from 2013 to 2018. Deaths were considerably more in the districts of the east coast of Sabah compared with districts in the west coast. During the study period, all DENV serotypes could be identified as serotypes circulating in Sabah. In 2018, the predominant serotype was DENV-3. The monthly peak of dengue infection varied in different years. In the logistic regression analysis, it was identified that children were 6.5 times, patients infected with mixed serotype of DENV were 13 times, and cases from the districts of the east coast were 5.2 times more likely to develop severe dengue. Conclusions: An increasing trend of dengue infection has been observed in Sabah. The burden of dengue, severe dengue, and mortality was noted especially in the districts of the east coast of Sabah. Severe dengue was most likely developed in children, cases from the east coast, and patients infected with mixed serotype of DENV.

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Section: Discussionmentioning

confidence: 99%

The east coast districts are the possible epicenter of severe dengue in Sabah

Kaur¹,

Rahim²,

Jaimin³

et al. 2020

J Physiol Anthropol

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“…albopictus in the transmission of DENV. Both mosquito species are reported to co-exist in the country [59][60][61][62]. Considering the vector competence of Ae.…”

Section: Discussionmentioning

confidence: 99%

Individual-based dengue virus surveillance in Aedes aegypti mosquitoes concurrently collected with suspected patients in Tarlac City, Philippines

Balingit¹,

Carvajal²,

Saito-Obata³

et al. 2020

Preprint

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Background: Vector control measures are critical in the prevention and reduction of dengue virus (DENV) transmission. In this context, an effective vector control is reliant not only on the knowledge of mosquito abundance, but also on the timely and accurate detection of mosquito infection. Mosquito-based virus surveillance programs typically rely on a pool-based mosquito testing, although whether individual-based mosquito testing could represent a feasible alternative is not largely studied. Applying an individual-based mosquito testing approach, we conducted a one-month DENV surveillance of adult Aedes (Ae.) aegypti mosquitoes around households of suspected dengue patients during the 2015 dengue peak season in Tarlac City, Philippines to more accurately assess the mosquito infection rate and identify the DENV serotypes and genotypes concurrently co-circulating in mosquitoes and patients.Methods: We performed a one-step multiplex real-time reverse transcription-polymerase chain reaction (RT-PCR) assay for the simultaneous DENV detection and serotyping in patients and individual female Ae. aegypti mosquito. Additionally, we performed sequencing and phylogenetic analyses to further characterize the detected DENVs in mosquitoes and patients at the genotype level.Results: We collected a total of 583 adult Ae. aegypti mosquitoes; of which, we individually tested 359 female mosquitoes for the presence of DENV. Ten (2.8%) among the 359 female mosquitoes were positive for the presence of DENV. We detected DENV-1, DENV-2, and DENV-4 in the field-collected mosquitoes, which were consistent with the serotypes concurrently infecting patients. Sequencing and phylogenetic analyses of the detected DENVs based on the partial envelope (E) gene revealed three genotypes concurrently present in the sampled mosquitoes and patients during the study period, namely: DENV-1 genotype IV, DENV-2 Cosmopolitan genotype, and DENV-4 genotype II.Conclusions: In this study, we demonstrate the utility of the one-step multiplex real-time RT-PCR assay in the individual-based DENV surveillance of mosquitoes. Our findings reinforce the significance of detecting and monitoring virus activity in local mosquito populations, which is critical for dengue prevention and control activities.

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“…This is because previous studies that surveyed selected areas of Metropolitan Manila indicated a high infestation rate of Ae. aegypti (>80%) (Mistica, et al 2019, Carvajal, Ho, et al 2019, thereby making it the primary vector for dengue transmission.…”

Section: Cross-correlation Analysismentioning

confidence: 99%

“…Since Ae. aegypti preferentially breeds in small water containers exposed to the outdoors (Carvajal, Ho, et al 2019, Ngugi, et al 2017, little rainfall might be sufficient to maintain optimal levels of water suitable for mosquito emergence. Conversely, enhanced rainfall might flush out mosquito eggs and larvae from breeding containers and reduce the sensitivity of the OI to changes in high residential density areas.…”

Section: Cross-correlation Analysismentioning

confidence: 99%

“…Previous studies have discussed the impact of precipitation on the increased number of dengue cases because of its role in increasing the number of available breeding sites for mosquitoes (Carvajal, Ho, et al 2019, Pasin, et al 2018. However, the transference of viruses from mosquitoes to humans occurs when the dynamics between the vector, the virus, and hosts are favorable (de Melo, Scherrer and Eiras 2012).…”

Section: Cross-correlation Analysismentioning

confidence: 99%

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Dengue Disease Dynamics are Modulated by the Combined Influence of Precipitation and Landscapes: A Machine Learning-based Approach

Francisco

Carvajal

Ryo

et al. 2020

Preprint

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BackgroundDengue is an endemic vector-borne disease influenced by environmental factors such as landscape and climate. Previous studies separately assessed the effects of landscape and climate factors on mosquito occurrence and dengue incidence. However, both factors interact in time and space to affect mosquito development and dengue disease transmission. For example, eggs laid in a suitable environment can hatch after being submerged in rain or flood water.ObjectivesThis study aimed to investigate the combined influences of landscape and climate factors on mosquito occurrence and dengue incidence.MethodsEntomological, epidemiological, and landscape data from the rainy season (July-December) were obtained from respective government agencies in Metro Manila, Philippines, from 2012 to 2014. Temperature, precipitation, and vegetation data were obtained through remote sensing. A random forest algorithm was used to select the landscape and climate variables. Afterwards, using the identified key variables, a model-based (MOB) recursive partitioning was implemented to test the combinatory influences of landscape and climate factors on the ovitrap index and dengue incidence.ResultsThe MOB recursive partitioning for the ovitrap index indicated that mosquito occurrence was higher in high residential density areas, where industrial areas also exist and are well connected with roads. Precipitation was another key covariate modulating the effects of landscape factors, possibly by expanding breeding sites and activating mosquito reproduction. Moreover, the MOB recursive partitioning indicated that precipitation was the main predictor of dengue incidence, with a stronger effect in high residential density and commercial areas.DiscussionPrecipitation with floods has epidemiologically important implications by damaging shelters and causing population displacement, thus increasing exposure to dengue vectors. Our findings suggest that the intensification of vector control during the rainy season can be prioritized in residential and commercial areas to better control dengue disease dynamics.

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An Ecological Context Toward Understanding Dengue Disease Dynamics in Urban Cities: A Case Study in Metropolitan Manila, Philippines

Cited by 7 publications

References 50 publications

The east coast districts are the possible epicenter of severe dengue in Sabah

The east coast districts are the possible epicenter of severe dengue in Sabah

Individual-based dengue virus surveillance in Aedes aegypti mosquitoes concurrently collected with suspected patients in Tarlac City, Philippines

Dengue Disease Dynamics are Modulated by the Combined Influence of Precipitation and Landscapes: A Machine Learning-based Approach

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