A dengue outbreak on a floating village at Cat Ba Island in Vietnam

Abstract

BackgroundA dengue outbreak in an ecotourism destination spot in Vietnam, from September to November 2013, impacted a floating village of fishermen on the coastal island of Cat Ba. The outbreak raises questions about how tourism may impact disease spread in rural areas.MethodsEpidemiological data were obtained from the Hai Phong Preventive Medical Center (PMC), including case histories and residential location from all notified dengue cases from this outbreak. All household addresses were geo-located. Knox test, a spatio-temporal analysis that enables inference dengue clustering constrained by space and time, was performed on the geocoded locations. From the plasma available from two patients, positive for Dengue serotype 3 virus (DENV3), the Envelope (E) gene was sequenced, and their genetic relationships compared to other E sequences in the region.ResultsOf 192 dengue cases, the odds ratio of contracting dengue infections for people living in the floating villages compared to those living on the island was 4.9 (95 % CI: 3.6-6.7). The space-time analyses on 111 geocoded dengue residences found the risk of dengue infection to be the highest within 4 days and a radius of 20 m of a given case. Of the total of ten detected clusters with an excess risk greater than 2, the cluster with the highest number of cases was in the floating village area (24 patients for a total duration of 31 days). Phylogenetic analysis revealed a high homology of the two DENV3 strains (genotype III) from Cat Ba with DENV3 viruses circulating in Hanoi in the same year (99.1 %).ConclusionsOur study showed that dengue transmission is unlikely to be sustained on Cat Ba Island and that the 2013 epidemic likely originated through introduction of viruses from the mainland, potentially Hanoi. These findings suggest that prevention efforts should be focused on mainland rather than on the island.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-015-2235-y) contains supplementary material, which is available to authorized users.

Socio-Ecological Factors Associated with Dengue Risk and Aedes aegypti Presence in the Galápagos Islands, Ecuador

“…Individuals with frequent travel to other islands, as well as between the islands and the continent, may be considered to be at higher risk for dengue infection. Previous studies of dengue on islands emphasized the importance of preventing the transmission of dengue from the mainland [ 55 ], as well as reintroduction from surrounding islands [ 56 ]. Prior studies of West Nile virus risk in the Galápagos found that the transportation of infected mosquitoes via airplanes was the most likely means that the virus would be introduced to the islands [ 18 ].…”

Characterizing dengue transmission in rural areas: A systematic review

“…These studies were divided into 2 categories: (1) articles that presented rural–urban comparison estimates ( n = 37) [ 4 – 7 , 9 , 25 , 39 , 42 – 44 , 49 , 53 , 59 – 62 , 65 , 69 , 72 , 75 , 78 , 83 , 85 , 86 , 88 , 93 , 95 – 97 , 101 , 109 , 119 , 120 , 125 , 126 , 133 , 135 ] and (2) articles that presented rural estimates ( n = 92) [ 4 – 9 , 19 , 25 , 40 – 71 , 73 – 78 , 80 – 82 , 84 , 85 , 87 , 89 – 94 , 97 – 100 , 102 – 109 , 111 – 119 , 121 , 122 , 124 – 132 ,…”

One Health Approach to Dengue Haemorrhagic Fever Control in Indonesia: A Systematic Review

“…People at the periphery identified a higher number of risk factors. Common misperceptions included confusion with other febrile diseases, lack of knowledge of transmission mechanisms, and misconceptions about mosquito behavior [79]. There was also in Pak-Ngum community, a lack of depth of knowledge regarding dengue [40].…”