A framework for assessing local transmission risk of imported malaria cases

Highly pathogenic avian influenza (HPAI) virus is one of the most virulent and infectious pathogens of poultry. As a response to HPAI epidemics, veterinary authorities implement preemptive depopulation as a controlling strategy. However, mass culling within a uniform radius of the infection site can result in unnecessary depopulation. Therefore, it is useful to quantify the transmission distance from infected premises (IPs) before determining the optimal area for preemptive depopulation. Accordingly, we analyzed the transmission risk within spatiotemporal clusters of IPs using transmission kernel estimates derived from phylogenetic clustering information on 311 HPAI H5N6 IPs identified during the 2016–2017 epidemic, Republic of Korea. Subsequently, we explored the impact of varying the culling radius on the local transmission of HPAI given the transmission risk estimates. The domestic duck farm density was positively associated with higher transmissibility. Ring culling over a radius of 3 km may be effective for areas with high dense duck holdings, but this approach does not appear to significantly reduce the risk for local transmission in areas with chicken farms. This study provides the first estimation of the local transmission dynamics of HPAI in the Republic of Korea as well as insight into determining an effective ring culling radius.

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Genetic evidence for imported malaria and local transmission in Richard Toll, Senegal

10.21203/rs.2.24566/v1 ◽

2020 ◽

Author(s):

Rachel F. Daniels ◽

Stephen F. Schaffner ◽

Yakou Dieye ◽

Gnagna Dieng ◽

Michael Hainsworth ◽

...

Keyword(s):

Genetic Relatedness ◽

Imported Malaria ◽

Intervention Selection ◽

Optimal Intervention ◽

Relatedness Analysis ◽

Molecular Barcode ◽

Gates Foundation ◽

Low Prevalence ◽

Imported Infections ◽

Local Transmission

Abstract Background: Malaria elimination efforts can be undermined by imported malaria infections. Imported infections are classified based on travel history.Methods: We applied a genetic strategy to better understand the contribution of imported infections and to test for local transmission in the very low prevalence region of Richard Toll, Senegal.Results: Genetic relatedness analysis, based upon molecular barcode genotyping data derived from diagnostic material, provided evidence for both imported infections and ongoing local transmission in Richard Toll. Evidence for imported malaria included finding that a large proportion of Richard Toll parasites were genetically related to parasites from Thiès, Senegal, a region of moderate transmission with extensive available genotyping data. Evidence for ongoing local transmission included finding parasites of identical genotype that persisted across multiple transmission seasons as well as enrichment of highly related infections within the households of non-travelers compared to travelers.Conclusions: These data indicate that, while a large number of infections may have been imported, there remains ongoing local malaria transmission in Richard Toll. These proof-of-concept findings underscore the value of genetic data to identify parasite relatedness and patterns of transmission to inform optimal intervention selection and placement. This work was supported by the Bill & Melinda Gates Foundation, Grant Number OPP1156051

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Imported Malaria to Makkah District, Saudi Arabia : Is There Any Risk of Local Transmission ?

Journal of the Egyptian Society of Parasitology ◽

10.12816/0033965 ◽

2016 ◽

Vol 46 (3) ◽

pp. 461-465

Author(s):

Mohamed El-Malky ◽

Mohammad S. Aldosari ◽

Ahmed Elsendiony

Keyword(s):

Saudi Arabia ◽

Imported Malaria ◽

Local Transmission

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Genetic evidence for imported malaria and local transmission in Richard Toll, Senegal

10.21203/rs.2.24566/v3 ◽

2020 ◽

Author(s):

Sarah K. Volkman ◽

Oumar Sarr ◽

Richard W. Steketee ◽

Stephen F. Schaffner ◽

Yakou Dieye ◽

...

Keyword(s):

Genetic Relatedness ◽

Imported Malaria ◽

Travel History ◽

Intervention Selection ◽

Optimal Intervention ◽

Relatedness Analysis ◽

Molecular Barcode ◽

Low Prevalence ◽

Imported Infections ◽

Local Transmission

Abstract Background Malaria elimination efforts can be undermined by imported malaria infections. Imported infections are classified based on travel history. Methods A genetic strategy was applied to better understand the contribution of imported infections and to test for local transmission in the very low prevalence region of Richard Toll, Senegal. Results Genetic relatedness analysis, based upon molecular barcode genotyping data derived from diagnostic material, provided evidence for both imported infections and ongoing local transmission in Richard Toll. Evidence for imported malaria included finding that a large proportion of Richard Toll parasites were genetically related to parasites from Thiès, Senegal, a region of moderate transmission with extensive available genotyping data. Evidence for ongoing local transmission included finding parasites of identical genotype that persisted across multiple transmission seasons as well as enrichment of highly related infections within the households of non-travellers compared to travellers. Conclusions These data indicate that, while a large number of infections may have been imported, there remains ongoing local malaria transmission in Richard Toll. These proof-of-concept findings underscore the value of genetic data to identify parasite relatedness and patterns of transmission to inform optimal intervention selection and placement.

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Genetic evidence for imported malaria and local transmission in Richard Toll, Senegal

10.21203/rs.2.24566/v2 ◽

2020 ◽

Author(s):

Sarah K. Volkman ◽

Oumar Sarr ◽

Richard W. Steketee ◽

Stephen F. Schaffner ◽

Yakou Dieye ◽

...

Keyword(s):

Genetic Relatedness ◽

Imported Malaria ◽

Travel History ◽

Intervention Selection ◽

Optimal Intervention ◽

Relatedness Analysis ◽

Molecular Barcode ◽

Low Prevalence ◽

Imported Infections ◽

Local Transmission

Abstract Background: Malaria elimination efforts can be undermined by imported malaria infections. Imported infections are classified based on travel history. Methods: We applied a genetic strategy to better understand the contribution of imported infections and to test for local transmission in the very low prevalence region of Richard Toll, Senegal. Results: Genetic relatedness analysis, based upon molecular barcode genotyping data derived from diagnostic material, provided evidence for both imported infections and ongoing local transmission in Richard Toll. Evidence for imported malaria included finding that a large proportion of Richard Toll parasites were genetically related to parasites from Thiès, Senegal, a region of moderate transmission with extensive available genotyping data. Evidence for ongoing local transmission included finding parasites of identical genotype that persisted across multiple transmission seasons as well as enrichment of highly related infections within the households of non-travelers compared to travelers. Conclusions: These data indicate that, while a large number of infections may have been imported, there remains ongoing local malaria transmission in Richard Toll. These proof-of-concept findings underscore the value of genetic data to identify parasite relatedness and patterns of transmission to inform optimal intervention selection and placement.

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Genetic evidence for imported malaria and local transmission in Richard Toll, Senegal

Malaria Journal ◽

10.1186/s12936-020-03346-x ◽

2020 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Rachel F. Daniels ◽

Stephen F. Schaffner ◽

Yakou Dieye ◽

Gnagna Dieng ◽

Michael Hainsworth ◽

...

Keyword(s):

Genetic Evidence ◽

Imported Malaria ◽

Local Transmission

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Downgrading disease transmission risk estimates using terminal importations

10.1101/265942 ◽

2018 ◽

Cited By ~ 3

Author(s):

Spencer J Fox ◽

Steven E Bellan ◽

T Alex Perkins ◽

Michael A Johansson ◽

Lauren Ancel Meyers

Keyword(s):

Infectious Diseases ◽

Disease Transmission ◽

A Priori ◽

Emerging Infectious Diseases ◽

Epidemiological Data ◽

Transmission Risk ◽

Risk Estimates ◽

Imported Cases ◽

Ecological Suitability ◽

Local Transmission

AbstractAs emerging and re-emerging infectious diseases like dengue, Ebola, chikungunya, and Zika threaten new populations worldwide, officials scramble to assess local severity and transmissibility, with little to no epidemiological history to draw upon. Standard methods for assessing autochthonous (local) transmission risk make either indirect estimates based on ecological suitability or direct estimates only after local cases accumulate. However, an overlooked source of epidemiological data that can meaningfully inform risk assessments prior to outbreak emergence is the absence of transmission by imported cases. Here, we present a method for updating a priori ecological estimates of transmission risk using real-time importation data. We demonstrate our method using Zika importation and transmission data from Texas in 2016, a high-risk region in the southern United States. Our updated risk estimates are lower than previously reported, with only six counties in Texas likely to sustain a Zika epidemic, and consistent with the number of autochthonous cases detected in 2017. Importation events can thereby provide critical, early insight into local transmission risks as infectious diseases expand their global reach.

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Review And Assessment Of Malaria Epidemic Situation And Re-Transmission Risk In A Central City Of China, 1950-2019

10.21203/rs.3.rs-49989/v1 ◽

2020 ◽

Author(s):

Wen-ting ZHA ◽

Guoqun LI ◽

Ruihua FENG ◽

Yu LIAO ◽

Nan ZHOU ◽

...

Keyword(s):

Malaria Control ◽

Malaria Elimination ◽

Imported Malaria ◽

Central China ◽

Transmission Risk ◽

World Health ◽

Local Case ◽

Imported Cases ◽

Control And Prevention ◽

And Control

Abstract Background: With characteristics of fast transmission and widespread, malaria was the most deadly parasite disease. In China, 13 ministries and commissions jointly issued the Action Plan For Malaria Eradication, which was aimed to reach malaria elimination by 2020. Scientific analysis of the epidemic situation and assessment of re-transmission risk of malaria in Changsha, an important city of central China, are of certain reference value for China to pass the World Health Organization malaria control assessment in 2020.Method: The epidemic situation and control process of malaria in Changsha from 1950 to 2019 have been illustrated, and an adjusted assessment method was used to analyze the transmission risk index (MRI) of imported malaria in different districts of Changsha in recent years. All data were from Changsha Center for Disease Control and Prevention (CDC).Results: (1) From 1950 to 2019, there were 282,394 incidences and 39 deaths of malaria in Changsha, the incidence rate has been controlled below 10/1,000,000 after 1990; The fatality rate of malaria in Changsha has always been at a low level, but it reached 10.28/1000 after 2010; (2) Before the year 1978, tertian was the major type of malaria in Changsha, which accounted for 92.71%, but the proportion of pernicious malaria gradually increased after 2000, which accounted for 69.3% since 2010. (3) From 1950 to 2009, the percentage of imported malaria cases in Changsha was only 2.93%; In April 2010, the last local case of malaria was reported in Liuyang, Changsha; After 2011, all cases of malaria in Changsha were imported cases, which were mainly from Africa and Southeast Asia. (4) The re-transmission risk of imported malaria in Changsha from high to low were Liuyang City, Yuelu District, Tianxin District, Yuhua District, Ningxiang County, Furong district, Wangcheng District, Changsha County and Kaifu District. Conclusion: After 70 years, implemented three stages of prevention and control measures, Changsha has achieved the goal of malaria elimination. However, with the imported cases increased, the risk of re-transmission of malaria in Changsha still exists, especially in Liuyang and Yuelu district. Malaria control and prevention should still be taken seriously as an important preventive work in case of the secondary spread.

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