Hello everyone! I’m Vanheuang Phommadeechack. Student ID: 6436660
I will answer and discuss questions below: How epidemiology of vectors improve vector control? (Give example and discuss)

Epidemiology is the study of diseases to investigate how, when and why the disease is occured. The information can be used to control the spread of the disease and prevent future outbreaks. In terms of entomology, epidemiology of vectors also important for prevention and vector controlling programs and understand vector capacity, the dynamic of vector population and disease. There are several factors that affect the current status of vector-borne diseases such as the Environmental factor, human, meteorological (temperature, humidity, visibility, and wind speed), seasonal and climate change.

For example the study that conducted by Tamaree et all (2021), they study a spatio-temporal analysis of scrub typhus and murine typhus in Laos, which we know these diseases are causes of febrile illness. Scrub typhus (ST) is caused by Orientia tsutsugamushi, transmitted by the bite of chiggers mites. Murine typhus (MT) is caused by Rickettsia typhi and is transmitted by fleas. Both diseases are neglected with under-estimated burdens on health and little is known about the temporal dynamics of these diseases, and the influence of climatic and environmental factors

In this study, they investigated individual-level demographic and behavioral characteristics of patients; spatial and temporal distributions; meteorological correlates of the temporal patterns; and environmental and geographic correlates of the spatiotemporal distributions.

The result shows that ST was highly occur during the wet season between July-September compared to the dry season whilst MT peaked in the dry season. ST incidence to fluctuations in relative humidity whereas MT was linked to variation in temperature. In addition, patients with ST infection were more likely to come from villages with higher levels of surface flooding with the patient-related or contact with the rice field.

The data suggest that the risk of disease will be increase as cities expand. They also suggested that the incidence and spatial distribution of both MT and ST will increase. According to the information of the distribution or the epidemiology of MT and ST, we will know the time period of disease outbreak and know the dynamic of the disease and vector … in Vientiane, which very helpful for using as the reference information for disease prevention and vector controlling program to reduce the risk of disease transmission.

Reference :Roberts T et all. A spatio-temporal analysis of scrub typhus and murine typhus in Laos; implications from changing landscapes and climate. PLoS Negl Trop Dis. 2021 Aug 25. doi: 10.1371/journal.pntd.0009685.

Thank you very much.

Rattanalak Jittungdee
6438165

Epidemiology is the study of how often diseases occur in different groups of people and why. Epidemiological information is used to plan and evaluate strategies to prevent illness and as a guide to the management of patients in whom the disease has already developed. The study of the outbreak can also help in planning, controlling, and monitoring the spread of the disease.

For example, a study by Leandro, André S et al. (2022) study about Citywide Integrated Aedes aegypti Mosquito Surveillance as Early Warning System for Arbovirus Transmission, Brazil. In this study, The Aedes aegypti mosquito is the primary vector of arboviruses. This mosquito species is common in urbanized areas in the tropics because it is highly adapted to live in close association with humans, preferentially feeding on the blood of human hosts and laying eggs in containers located around human dwellings.

They report on a 4-year integrated citywide vector surveillance approach that involved extensive use of adult mosquito traps, molecular diagnostic testing for natural arbovirus infection in live collected mosquito specimens, construction of transmission risk maps, and performance of timely vector control intervention <48 h after mosquito collection. In this scheme, vector control was intensified in areas with a higher risk for transmission instead of maintaining homogeneous vector control efforts over the landscape. In addition, they evaluated the correspondence of larval- and adult-based indices with the epidemiologic trend in the city of Foz do Iguaçu, Brazil, during 2017–2020.

The results show, that comparing the predictive ability of traditional versus adult indices revealed that indices based on adult trapping consistently performed much better than indices based on larval surveys. and one criterion that could be used to prioritize areas is the occurrence of Ae. aegypti female mosquitoes are naturally infected with DENV, ZIKV, or CHIKV. In Foz do Iguaçu, an inspection of the 3,476 Adultraps took 4 days, and real-time qPCR results were available, on average, 36 h after all Adultraps were inspected and live mosquitoes collected.

In conclusion, They conducted a 4-year citywide study to deepen the entomologic and epidemiologic features of dengue transmission in Foz do Iguaçu by focusing on developing indicators based on adult mosquito trapping. They proposed a surveillance system that can predict a dengue outbreak with high accuracy, and indices based on adult trapping are able to predict a dengue outbreak 4 weeks after DENV detection in adult mosquitoes. In addition, the adoption of easily accessible technological resources makes it possible for the model to be replicated in other localities.

Ref: Leandro, A. S., de Castro, W., Lopes, R. D., Delai, R. M., Villela, D., & de-Freitas, R. M. (2022). Citywide Integrated Aedes aegypti Mosquito Surveillance as Early Warning System for Arbovirus Transmission, Brazil. Emerging infectious diseases, 28(4), 701–706. https://doi.org/10.3201/eid2804.211547

Hi there 🙂 I’m Tipawan Ammarit student ID: 6438166.
How does epidemiology of vectors improve vector control? (Give an example and discuss)

Firstly, epidemiology is the study (scientific, systematic, and data-driven) of the distribution (frequency, pattern) and determinants (causes, risk factors) of health-related states and events (not just diseases) in specified populations (neighborhood, school, city, state, country, global). Therefore, epidemiology information can help to improve vector control management and planning easily by mapping the distribution of vectors, diseases, and case reports. Epidemiology offers powerful tools to quantify the degree to which risk factors and humanitarian interventions affect population health in a crisis. Thus this method is appropriate to use when having disease outbreaks because it’s an easy assessment to find the relevant indicator of the spreading of vectors or diseases.

For example, Fijman,N.S., and Yee,D.A.(2022) research has interested in mapping yellow fever epidemics in the United States. Since, yellow fever (YF) plagued the United States from the 1690s until 1905, resulting in thousands of deaths. Within the US, Aedes aegypti is the only YF vector and almost no data exists for the location of this species prior to the early 1900s. The aim of this study is to determine the historical range of Ae. aegypti. They examined the occurrence of YF epidemics across time and space. Moreover, they hypothesized that historically Ae. aegypti was driven by human population density.

Methodology to test this hypothesis, they collect a list of cases in the US including; human population density, location, and the number of infected people. These data were mapped using ArcGIS and were analyzed using linear regression models to determine the relationship among variables.

The results show the historic range was generally south of 40 latitudes, from Texas in the west to Florida in the east, with concentrations along major waterways like the Mississippi River. Infected individuals and human population density were strongly correlated across the whole dataset as well as by decade. Lastly, although other factors likely affected the range of Ae. aegypti, they found that human population density was related to the number of infected people with historic YF infections.

Reference
Fijman, N. S., & Yee, D. A. (2022). Mapping Yellow fever epidemics as a potential indicator of the historical range of Aedes aegypti in the United States. Memórias Do Instituto Oswaldo Cruz, 117. https://doi.org/10.1590/0074-02760220306

Thank you very much.