Browsing by Author "Lee, Joon-Hak"

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Areas for improvement to further reduce malaria burden in sub-Saharan Africa?
(2015-03) Lee, Ju Sung; Tak, Hyo Jung; Lee, Joon-Hak
In 2012, sub-Saharan African countries account for 80% of all malaria cases worldwide. Malaria hampers their development both socially and economically. Global efforts to control malaria in sub-Saharan Africa have been placed in the past. In particular, since 2005, funding for Malaria control has increased dramatically.However, little is known about malaria incidence and mortality rate among sub-Saharan African countries overall. Only few studies investigated, and focused on a few countries in sub-Saharan Africa with limited attributing factors. We expect that national level operational intervention, malaria funding, and economic factors would be associated with reduction of malaria incidence and mortality. Our objectives are to assess progress of malaria control in sub-Saharan Africa overall and associated factors with malaria control. With data between 2005 and 2013 from World Malaria Reports and The World Bank, a dataset was constructed to associate reduction of malaria incidence and mortality rate with national economic factors, malaria funding, and malaria operational interventions. General Liner Model was used for the statistical analyses. Malaria incidence rate was inversely associated with GDP per capita (AME = -0.267, p-value = 0.004), but was positively associated with foreign aid per capita (AME = 0.158, p-value = 0.013)and ACT treatment courses delivered (AME = 0.069, p-value = 0.000). Malaria mortality rate was positively associated with foreign aid per capita (AME = 0.017, p-value = 0.016) and with increased number of ACT treatment courses delivered (AME = 0.073, p-value = 0.004). Increase of ODA per capita was associated with increase of distributed number of ITN/LLIN (AME = 6.601, p-value = 0.006). IRS (AME = 9.421, p-value = 0.001), and ACT (AME = 6.84, p-value = 0.064). In addition, increase of foreign aid per capita was positively associated with distributed number of IRS (AME = 4.070, p-value = 0.00). Economic growth and internal funding increase should be pursued for sustainable malaria control. Careful attention to utilizing operational intervention effectively and adequate education of its utilization is required. As the complicated malaria control can be achieved by multiple efforts, systematic strategies including education, operational management, adequate infrastructure, and cooperation between organizations should be taken into account.
EVALUATION OF STORM DRAIN SYSTEM COMPONENTS FOR ABUNDANCE OF THE PRIMARY WEST NILE VIRUS VECTOR IN FORT WORTH
(2014-03) Bhandarkar Srinivas, Kiran; Bennett, Brandon S.; Lee, Joon-Hak
Purpose (a): In order to better assess and control the risk of human exposure to the West Nile virus (WNV), it is necessary to identify breeding habitats of the WNV mosquito vector and understand habitat-associated environmental factors affecting dynamics of the mosquito population. In an urban setting, storm drain systems have been considered a primary breeding site for the primary WNV vector mosquito, Culex quinquefasciatus. The objective of this study was to associate the abundance of the primary West Nile virus vector with components of the urban storm drain system in Fort Worth. Methods (b): Weekly abundance of the primary WNV mosquito was monitored in 50 locations across the City of Fort Worth from June through October, 2013. The data on the storm drain systems was obtained from the City of Fort Worth. In order to test an association of the WNV primary vector abundance with each component of the City’s storm drain system, Spearman’s correlation, t-test or ANOVA was used. Results (c): Spearman’s correlation showed that more mosquitoes were captured at the collection sites that had a manhole within an area with 400 feet (ρ = 0.293, p-value = 0.039) from the collection site. The female Culex mosquito counts were considerably higher in areas that had a pond within the circled area of 800 feet (ρ = 0.303, p-value = 0.033) from the collection site. The number of storm drain inlets, in falls, outfalls and swimming pools however, had considerably lower number of captured mosquitoes. Further analysis was done using ANOVA and t-test to determine association. Significant association was seen with manholes at 400 feet (t= -2.320, p value = 0.025, df = 48) from the trapping site while inlets and ponds at any distance did not show any significant association. Conclusions (d): The number of storm drain inlets which is considered to be a primary breeding site for the Culex quinquefasciatus mosquito does not have any relationship in determining the mosquito population. The presence of manhole or ponds appeared to have an influence on the vector population abundance. An increase in the sample size would be necessary to establish an association between the storm drain inlet and mosquito abundance.
EVALUATION OF WEATHER FACTORS FOR ABUNDANCE OF THE PRIMARY WEST NILE VIRUS VECTOR IN FORT WORTH
(2014-03) Bhandarkar Srinivas, Kiran; Bennett, Brandon S.; Lee, Joon-Hak
Purpose (a): INTRODUCTION: Vector-borne diseases like Malaria, Dengue, Japanese Encephalitis, Filariasis and West Nile fever have been affecting millions of people around the world. In vector-borne diseases, vector distribution and abundance is critical factor to predict occurrence and magnitude of a vector-borne disease. West Nile encephalitis is a vector-borne disease of concern in Texas, particularly in the Dallas-Fort Worth region: however, little attempt has been made to associate the abundance of the vector population with local weather patterns. OBJECTIVE: The objective of this study was to associate abundance of the primary West Nile virus vector, Culex quinequefasciatus, with local weather factors in the City of Fort Worth. Methods (b): Abundance of the primary WNV vector mosquito population was monitored by weekly mosquito trappings using CDC gravid mosquito traps. Fifty sites across the City of Fort Worth were selected to estimate abundance of the vector mosquito population and mosquito trappings were conducted from mid-April through end of October. Local weather data from Dallas-Fort Worth International Airport were obtained from the National Climate Data Center. Pearson’s correlation was used to identify a linear relationship and determine the strength association between the mosquito abundance and the various components of weather. Results (c): Analysis showed a peak in the mosquito population during the months of June, July and September while the rest of the months had comparatively lower counts. These mosquito numbers showed to have strong positive linear relationships with weekly average (r = 0.703, p = 0.000), maximum (r = 0.704, p = 0.000) and minimum (r = 0.693, p = 0.000) temperatures and 3 day precipitation (r = 0.439, p = 0.022) while the weekly average wind speed (r = -0.453, p = 0.018) and minimum humidity (r = -0.390, p = 0.045) had significant negative correlations. Linear positive associations were also noticed with the 3 day temperature and collection day temperature averages. Conclusions (d): Weekly temperature averages and 3day precipitation are strongly associated with the abundance of the West Nile virus vector mosquito population while humidity and wind speed showed little effect on the vector abundance. Further analysis will be conducted.
Primary care clinics can be a source of exposure to virulent Clostridium (now Clostridioides) difficile: An environmental screening study of hospitals and clinics in Dallas-Fort Worth region
(PLOS, 2019-08-15) Simecka, Jerry W.; Fulda, Kimberly G.; Pulse, Mark; Lee, Joon-Hak; Vitucci, John; Nguyen, Phung; Taylor, Patricia; Filipetto, Frank; Espinoza, Anna M.; Sharma, Sushma
C. difficile is an endospore-forming pathogen, which is becoming a common cause of microbial health-care associated gastrointestinal disease in the United States. Both healthy and symptomatic patients can shed C. difficile spores into the environment, which can survive for long periods, being resistant to desiccation, heat, and disinfectants. In healthcare facilities, environmental contamination with C. difficile is a major concern as a potential source of exposure to this pathogen and risk of disease in susceptible patients. Although hospital-acquired infection is recognized, community-acquired infection is an increasingly recognized health problem. Primary care clinics may be a significant source of exposure to this pathogen; however, there are limited data about presence of environmental C. difficile within clinics. To address the potential for primary care clinics as a source of environmental exposure to virulent C. difficile, we measured the frequency of environmental contamination with spores in clinic examination rooms and hospital rooms in Dallas-Fort Worth (DFW) area of Texas. The ribotypes and presence of toxin genes from some environmental isolates were compared. Our results indicate primary care clinics have higher frequencies of contamination than hospitals. After notification of the presence of C. difficile spores in the clinics and an educational discussion to emphasize the importance of this infection and methods of infection prevention, environmental contamination in clinics was reduced on subsequent sampling to that found in hospitals. Thus, primary care clinics can be a source of exposure to virulent C. difficile, and recognition of this possibility can result in improved infection prevention, potentially reducing community-acquired C. difficile infections and subsequent disease.
The Population Abundance and Associated Geographic and Demographic Factors of the Dengue Vectors, Aedes Aegypti and Aedes Albopictus in Dallas County, TX, USA
(2007-05-01) Stahl, Matthew S.; Lurie, Sue; Lee, Joon-Hak
Stahl, Matthew S., The Population Abundance and Associated Geographic and Demographic factors of the Dengue Vectors Aedes aegypti and Aedes albopictus in Dallas County, TX. Master of Public Health (Environmental Health), May 2007, 40 pp., 7 figures, 2 tables, bibliography, 72 titles. The risk for dengue outbreak was assessed in North Central Texas in 2006 in response to increased case numbers in Texas and Mexican states in 2005. Data were collected from 54 sites in Dallas County, TX using oviposition traps and estimates from U.S. Census and Sourcebook America databases. Higher vegetation and shade displayed more Aedes species; standing water also showed more Aedes albopictus. Lower home values and lower incomes corresponded to more Aedes aegypti; lower household density displayed more Aedes albopictus. Other socio-economic and demographic factors did not have significant association with abundance. The methodology of this study may serve as a model for assessment of dengue vector abundance in other regions.