autochthonous transmission
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2022 ◽  
Author(s):  
Susan Jarvi ◽  
Kirsten Snook ◽  
Alfred Mina ◽  
Malia Lyons ◽  
Sarah Ortega ◽  
...  

Abstract Background: Hawaii is the hotspot for rat lungworm disease (angiostrongyliasis) caused by the nematode Angiostrongylus cantonensis in the USA. In humans, PCR of the CSF is typically used for diagnosis, however, collection of CSF requires hospitalization. Here, we evaluate the efficacy of two different PCR tests to detect A.cantonensis DNA in multiple tissues including blood from a rabbit presumably infected by eating contaminated lettuce. Methods: Two different PCR assays (AcanR3990, and AcanITS1) were used comparatively to test DNA extracted from slug and rabbit tissues. Assays were conducted using established protocols and were run in triplicate, with negative (dH20) controls included throughout. Results: A juvenile Parmarian martensi (semi-slug) found in local lettuce tested positive for the presence of Angiostrongylus cantonensis DNA. A family and their two domestic rabbits (Oryctolagus cuniculus) consumed this lettuce twice within the five days preceding testing. One rabbit exhibited symptoms consistent with eosinophilic meningitis 3-6 days after being fed the lettuce. Appropriate veterinary treatment was ineffective and the rabbit was subsequently euthanized. This study comparatively applies two different PCR assays to detect A. cantonensis DNA in the peripheral blood, cerebrospinal fluid, brain, heart, and lung tissue of this rabbit, and provides data implicating parasite transmission via contaminated home-grown lettuce. Six of the nine brain DNA samples, as well as the CSF sample, tested positive in replicate or triplicate for A. cantonensis DNA with both PCR assays. The AcanR3990 assay also detected A. cantonensis DNA from the lung, heart septum, all nine samples from the brain, and blood products (plasma, EDTA-treated whole blood, and buffy coat/red blood cells) in replicate or triplicate.


2021 ◽  
Vol 44 ◽  
pp. 102165
Author(s):  
Joaquín Salas-Coronas ◽  
María Dolores Bargues ◽  
Ana Belén Lozano-Serrano ◽  
Patricio Artigas ◽  
Alberto Martínez-Ortí ◽  
...  

2021 ◽  
Vol 15 (3) ◽  
pp. e0009063
Author(s):  
Bingyi Yang ◽  
Brooke A. Borgert ◽  
Barry W. Alto ◽  
Carl K. Boohene ◽  
Joe Brew ◽  
...  

Florida faces the challenge of repeated introduction and autochthonous transmission of arboviruses transmitted by Aedes aegypti and Aedes albopictus. Empirically-based predictive models of the spatial distribution of these species would aid surveillance and vector control efforts. To predict the occurrence and abundance of these species, we fit a mixed-effects zero-inflated negative binomial regression to a mosquito surveillance dataset with records from more than 200,000 trap days, representative of 53% of the land area and ranging from 2004 to 2018 in Florida. We found an asymmetrical competitive interaction between adult populations of Aedes aegypti and Aedes albopictus for the sampled sites. Wind speed was negatively associated with the occurrence and abundance of both vectors. Our model predictions show high accuracy (72.9% to 94.5%) in validation tests leaving out a random 10% subset of sites and data since 2017, suggesting a potential for predicting the distribution of the two Aedes vectors.


Author(s):  
Yi Zhang ◽  
Hongyi Chen ◽  
Jingen Wang ◽  
Shumei Wang ◽  
Jing Wu ◽  
...  

BackgroundDengue fever is a mosquito-borne febrile illness. Southeast Asia experienced severe dengue outbreaks in 2019, and over 1000 cases had been reported in Jiangxi, a previously known low-epidemic region in China. However, the emergence of a dengue virus epidemic in a non-epidemic region remains unclear.MethodsWe enrolled 154 dengue fever patients from four hospitals in Jiangxi, from April 2019 to September 2019. Real-time PCR, NS1 antigen rapid test, and IgM, IgG tests were performed, and 14 samples were outsourced to be sequenced metagenomically.ResultsAmong the 154 cases, 42 were identified as imported and most of them returned from Cambodia. A total of 113 blood samples were obtained and 106 were identified as DENV-1, two as DENV-2, and five were negative through RT-PCR. All DENV-1 strains sequenced in this study were all classified to one cluster and owned a high similarity with a Cambodia strain isolated in 2019. The evolutionary relationships of amino acid were consistent with that of nucleotide genome result. The sequence-based findings of Jiangxi strains were consistent with epidemiological investigation.ConclusionEpidemiological analysis demonstrated that the emergence of dengue cases led to autochthonous transmission in several cities in Jiangxi, a low-epidemic region before. This study emphasized future prevention and control of dengue fever in both epidemic and non-epidemic regions.


Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 294
Author(s):  
Jennifer S. Lord

The known distribution of Japanese encephalitis (JE) is limited to Asia and Australasia. However, autochthonous transmission of Japanese encephalitis virus was reported in Africa for the first time in 2016. Reasons for the current geographic restriction of JE and the circumstances that may permit emergence in non-endemic areas are not well known. Here, I assess potential changes in vector breeding habitat and livestock production in Africa that are conducive to JEV transmission, using open-source data available from the Food and Agriculture Organization between 1961 and 2019. For 16 of 57 countries in Africa, there was evidence of existing, or an increase in, conditions potentially suitable for JE emergence. This comprised the area used for rice production and the predicted proportion of blood meals on pigs. Angola, where autochthonous transmission was reported, was one of these 16 countries. Studies to better quantify the role of alternative hosts, including domestic birds in transmission in endemic regions, would help to determine the potential for emergence elsewhere. In Africa, surveillance programs for arboviruses should not rule out the possibility of Japanese encephalitis virus (JEV) circulation in areas with high pig or bird density coincident with Culicine breeding habitats.


2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Prayuth Sudathip ◽  
Suravadee Kitchakarn ◽  
Jui A. Shah ◽  
Donal Bisanzio ◽  
Felicity Young ◽  
...  

Abstract Background Thailand’s success in reducing malaria burden is built on the efficient “1-3-7” strategy applied to the surveillance system. The strategy is based on rapid case notification within 1 day, case investigation within 3 days, and targeted foci response to reduce the spread of Plasmodium spp. within 7 days. Autochthonous transmission is still occurring in the country, threatening the goal of reaching malaria-free status by 2024. This study aimed to assess the effectiveness of the 1-3-7 strategy and identify factors associated with presence of active foci. Methods Data from the national malaria information system were extracted from fiscal years 2013 to 2019; after data cleaning, the final dataset included 81,012 foci. A Cox’s proportional hazards model was built to investigate factors linked with the probability of becoming an active focus from 2015 to 2019 among foci that changed status from non-active to active focus during the study period. We performed a model selection technique based on the Akaike Information Criteria (AIC). Results The number of yearly active foci decreased from 2227 to 2013 to 700 in 2019 (68.5 %), and the number of autochthonous cases declined from 17,553 to 3,787 (78.4 %). The best Cox’s hazard model showed that foci in which vector control interventions were required were 18 % more likely to become an active focus. Increasing compliance with the 1-3-7 strategy had a protective effect, with a 22 % risk reduction among foci with over 80 % adherence to 1-3-7 timeliness protocols. Other factors associated with likelihood to become or remain an active focus include previous classification as an active focus, presence of Plasmodium falciparum infections, level of forest disturbance, and location in border provinces. Conclusions These results identified factors that favored regression of non-active foci to active foci during the study period. The model and relative risk map align with the national malaria program’s district stratification and shows strong spatial heterogeneity, with high probability to record active foci in border provinces. The results of the study may be useful for honing Thailand’s program to eliminate malaria and for other countries aiming to accelerate malaria elimination.


Author(s):  
Bethan Cracknell Daniels ◽  
Katy Gaythorpe ◽  
Natsuko Imai ◽  
Ilaria Dorigatti

Abstract Background There is concern about the risk of yellow fever (YF) establishment in Asia, owing to rising numbers of urban outbreaks in endemic countries and globalisation. Following an outbreak in Angola in 2016, YF cases were introduced into China. Prior to this, YF had never been recorded in Asia, despite climatic suitability and the presence of mosquitoes. An outbreak in Asia could result in widespread fatalities and huge economic impact. Therefore, quantifying the potential risk of YF outbreaks in Asia is a public health priority. Methods Using international flight data and YF incidence estimates from 2016, we quantified the risk of YF introduction via air travel into Asia. In locations with evidence of a competent mosquito population, the potential for autochthonous YF transmission was estimated using a temperature-dependent model of the reproduction number and a branching process model assuming a negative binomial distribution. Results In total, 25 cities across Asia were estimated to be at risk of receiving at least one YF viraemic traveller during 2016. At their average temperatures, we estimated the probability of autochthonous transmission to be <50% in all cities, which was primarily due to the limited number of estimated introductions that year. Conclusion Despite the rise in air travel, we found low support for travel patterns between YF endemic countries and Asia resulting in autochthonous transmission during 2016. This supports the historic absence of YF in Asia and suggests it could be due to a limited number of introductions in previous years. Future increases in travel volumes or YF incidence can increase the number of introductions and the risk of autochthonous transmission. Given the high proportion of asymptomatic or mild infections and the challenges of YF surveillance, our model can be used to estimate the introduction and outbreak risk and can provide useful information to surveillance systems.


Acta Tropica ◽  
2021 ◽  
Vol 213 ◽  
pp. 105749
Author(s):  
Victoriano Díaz-Sáez ◽  
Victoriano Corpas-López ◽  
Gemma Merino-Espinosa ◽  
María Jesús Morillas-Mancilla ◽  
Naima Abattouy ◽  
...  

2020 ◽  
Vol 14 (12) ◽  
pp. e0008941
Author(s):  
Gladys Gutiérrez-Bugallo ◽  
Antoine Boullis ◽  
Yanet Martinez ◽  
Lyza Hery ◽  
Magdalena Rodríguez ◽  
...  

Background Like many countries from the Americas, Cuba is threatened by Aedes aegypti-associated arboviruses such as dengue (DENV), Zika (ZIKV), and chikungunya (CHIKV) viruses. Curiously, when CHIKV was actively circulating in the region in 2013–2014, no autochthonous transmission of this virus was detected in Havana, Cuba, despite the importation of chikungunya cases into this city. To investigate if the transmission ability of local mosquito populations could explain this epidemiological scenario, we evaluated for the first time the vector competence of two Ae. aegypti populations (Pasteur and Párraga) collected from Havana for dengue virus type 1 (DENV-1), CHIKV, and ZIKV. Methodology/Principal findings Mosquito populations were fed separately using blood containing ZIKV, DENV-1, or CHIKV. Infection, dissemination, and transmission rates, were estimated at 3 (exclusively for CHIKV), 7, and 14 days post exposure (dpe) for each Ae. aegypti population-virus combination. Both mosquito populations were susceptible to DENV-1 and ZIKV, with viral infection and dissemination rates ranging from 24–97% and 6–67% respectively. In addition, CHIKV disseminated in both populations and was subsequently transmitted. Transmission rates were low (<30%) regardless of the mosquito population/virus combination and no ZIKV was detected in saliva of females from the Pasteur population at any dpe. Conclusions/Significance Our study demonstrated the ability of Ae. aegypti from Cuba to transmit DENV, ZIKV, and CHIKV. These results, along with the widespread distribution and high abundance of this species in the urban settings throughout the island, highlight the importance of Ae. aegypti control and arbovirus surveillance to prevent future outbreaks.


Author(s):  
Janna M Schurer ◽  
Polly Tsybina ◽  
Karen M Gesy ◽  
Temitope U Kolapo ◽  
Stuart Skinner ◽  
...  

Abstract Alveolar echinococcosis (AE) is a life-threatening parasitic disease caused by the zoonotic cestode Echinococcus multilocularis. Our goals were to confirm infection, identify species, and analyze biogeographical origin of metacestode tissues from a suspected human AE case in Saskatchewan, Canada. We conducted polymerase chain reaction (PCR) targeting the nad1 mitochondrial gene for E. multilocularis and the rrnS ribosomal RNA gene for E. granulosus and conducted haplotype analysis at the nad2 locus. Our analysis confirmed AE and indicated that sequences matched infected Saskatchewan coyotes and European E3/E4 haplotypes. The patient had no travel history outside North America. This suggests autochthonous transmission of a European-type strain.


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