Autochthonous Dengue Fever Cases Research Articles

Flexibility of ED surveillance system to monitor dengue outbreak in Reunion Island

Flexibility of ED surveillance system to monitor dengue outbreak in Reunion Island

Epidemiological Characteristics and Risk Factors of Dengue Infection in Korean Travelers.

Dengue viral infection has rapidly spread around the world in recent decades. In Korea, autochthonous cases of dengue fever have not been confirmed yet. However, imported dengue cases have been increased since 2001. The risk of developing severe dengue in Korean has been increased by the accumulation of past-infected persons with residual antibodies to dengue virus and the remarkable growth of traveling to endemic countries in Southeast Asia. Notably, most of imported dengue cases were identified from July to December, suggesting that traveling during rainy season of Southeast Asia is considered a risk factor for dengue infection. Analyzing national surveillance data from 2011 to 2015, males aged 20–29 years are considered as the highest risk group. But considering the age and gender distribution of travelers, age groups 10–49 except 20–29 years old males have similar risks for infection. To minimize a risk of dengue fever and severe dengue, travelers should consider regional and seasonal dengue situation. It is recommended to prevent from mosquito bites or to abstain from repetitive visit to endemic countries. In addition, more active surveillance system and monitoring the prevalence asymptomatic infection and virus serotypes are required to prevent severe dengue and indigenous dengue outbreak.

Autochthonous dengue fever, Tokyo, Japan, 2014.

After 70 years with no confirmed autochthonous cases of dengue fever in Japan, 19 cases were reported during August-September 2014. Dengue virus serotype 1 was detected in 18 patients. Phylogenetic analysis of the envelope protein genome sequence from 3 patients revealed 100% identity with the strain from the first patient (2014) in Japan.

Autochthonous Dengue Fever, Tokyo, Japan, 2014

After 70 years with no confirmed autochthonous cases of dengue fever in Japan, 19 cases were reported during August–September 2014. Dengue virus serotype 1 was detected in 18 patients. Phylogenetic analysis of the envelope protein genome sequence from 3 patients revealed 100% identity with the strain from the first patient (2014) in Japan.

An autochthonous outbreak of dengue type 1 in Tokyo, Japan 2014

An outbreak of autochthonous dengue fever was reported in August 2014, with cases suspected mainly from Yoyogi Park in Tokyo. This is the first epidemic of dengue fever in Japan since 1945. From August to October 2014, the following measures were taken to control the outbreak: 1) risk communication and information sharing; 2) active case finding; 3) vector surveillance in affected sites; and 4) laboratory testing. We also reviewed the surveillance data as reported to the National Epidemiological Surveillance of Infectious Diseases during the 44 epidemiological weeks. results: An official dengue fever call center was set up temporarily for the general public and 3,005 calls were received. The Tokyo Metropolitan Government issued 39 press releases regarding patients and nine related to dengue virus (DENV) detection and vector control activities for the media. Confirmed autochthonous dengue fever cases were reported between the 35th and 44th epidemiological weeks. Out of 160 cases of outbreak, 108 (67.5%) confirmed cases were reported in Tokyo. The estimated illness onset dates were between August 9 and October 7, and estimated dates of infections were between August 3 and October 3, 2014. The data suggest that the infective mosquitoes had already been present in Yoyogi Park at the end of July 2014. During the weekly vector surveillance at Yoyogi Park, a total of 1,152 adult mosquitoes, of which 856 (73.3%) were Aedes mosquitoes, were collected over 11 weeks by a light trap with dry ice. DENV was detected from adult Aedes mosquito samples collected on the 2nd, 9th, and 16th of September, 2014. Serum samples from 240 suspected cases were examined at the Tokyo Metropolitan Institute of Public Health, and 78 were positive for the DENV NS1 antigen, DENV-specific IgM antibody, or DENV nucleic acid with reverse transcriptase polymerase chain reaction (RT-PCR) (NS1: 66 cases; IgM: 50 cases; PCR: 57 cases). Genetic analysis of DENV-positive serum and mosquito samples found all to be categorized as DENV-serotype 1 (gene type I). Phylogenetic analysis of the envelope protein genome sequence from patients and mosquitoes in Tokyo revealed more than 99% similarity with each other and with the strain from the first outbreak-associated patient in Saitama. Measures important for control of infectious disease epidemic were learned during this recent indigenous dengue outbreak in Tokyo. It also highlighted the importance of preparedness for epidemics of indigenous or imported infectious diseases, especially in light of the fact that Tokyo is in preparation for the Olympic and Paralympic Games in 2020.

Imported Dengue Cases, Weather Variation and Autochthonous Dengue Incidence in Cairns, Australia

BackgroundDengue fever (DF) outbreaks often arise from imported DF cases in Cairns, Australia. Few studies have incorporated imported DF cases in the estimation of the relationship between weather variability and incidence of autochthonous DF. The study aimed to examine the impact of weather variability on autochthonous DF infection after accounting for imported DF cases and then to explore the possibility of developing an empirical forecast system.Methodology/principal findsData on weather variables, notified DF cases (including those acquired locally and overseas), and population size in Cairns were supplied by the Australian Bureau of Meteorology, Queensland Health, and Australian Bureau of Statistics. A time-series negative-binomial hurdle model was used to assess the effects of imported DF cases and weather variability on autochthonous DF incidence. Our results showed that monthly autochthonous DF incidences were significantly associated with monthly imported DF cases (Relative Risk (RR):1.52; 95% confidence interval (CI): 1.01–2.28), monthly minimum temperature (oC) (RR: 2.28; 95% CI: 1.77–2.93), monthly relative humidity (%) (RR: 1.21; 95% CI: 1.06–1.37), monthly rainfall (mm) (RR: 0.50; 95% CI: 0.31–0.81) and monthly standard deviation of daily relative humidity (%) (RR: 1.27; 95% CI: 1.08–1.50). In the zero hurdle component, the occurrence of monthly autochthonous DF cases was significantly associated with monthly minimum temperature (Odds Ratio (OR): 1.64; 95% CI: 1.01–2.67).Conclusions/significanceOur research suggested that incidences of monthly autochthonous DF were strongly positively associated with monthly imported DF cases, local minimum temperature and inter-month relative humidity variability in Cairns. Moreover, DF outbreak in Cairns was driven by imported DF cases only under favourable seasons and weather conditions in the study.

Chikungunya and dengue autochthonous cases in Europe, 2007–2012

A large number of autochthonous cases of dengue fever (2237) and chikungunya fever (231) occurred in Europe (Italy, France, Croatia, Madeira) during the period covered by our analysis (2007-2012). In all dengue outbreaks, the circulating strain, identified by means of molecular analysis, was the DENV-1 strain. Dengue and chikungunya are infectious diseases that often result in hospitalizations and are associated with high public health costs. The dengue epidemic on the island of Madeira resulted in 122 hospitalizations. Only one death (from chikungunya) occurred but long-term sequelae were described after the chikungunya outbreak in Emilia-Romagna, Italy. Vector control is key to reducing the impact of these diseases. During the chikungunya outbreak in Italy and the dengue outbreak in Madeira, appropriate measures for the control of mosquitoes (Aedes aegypti and Aedes albopictus) were effectively implemented. The effectiveness of these measures (reducing the number of breeding sites, application of pesticides and insecticides, public health education) was shown in the context of these real-life outbreaks. All the pre-requisites for autochthonous transmission of both dengue virus and chikungunya virus (vectors, viremic returned travellers, climatic conditions) are present in Europe. Constant surveillance is imperative.

Identification of dengue viruses in naturally infected Aedes aegypti females captured with BioGents (BG)-Sentinel traps in Manaus, Amazonas, Brazil

In Manaus, the first autochthonous cases of dengue fever were registered in 1998. Since then, dengue cases were diagnosed by the isolation of viruses 1, 2, 3, and 4. One hundred eighty-seven mosquitoes were collected with BioGents (BG)-Sentinel traps in 15 urban residential areas in the Northern Zone of Manaus and processed by molecular tests. Infections with dengue viruses 1, 2, 3, and 4 and a case of co-infection with dengue viruses 2 and 3 were identified. These findings corroborate the detection of dengue in clinical samples and reinforce the need for epidemiological surveillance by the Health authorities.

Molecular characterization of dengue virus 1 from autochthonous dengue fever cases in Croatia

In the summer of 2010, two autochthonous dengue fever cases were detected in Croatia. Here we report the retrospective detection of an additional case of dengue fever, representing the first sustained autochthonous transmission in Europe since 1928. In addition, we present the phylogenetic analyses based on two sequences from the Pelješac peninsula, southern Croatia. The sequences were identified as dengue virus genotype 1 and recovered from two out of the three Pelješac patients in whom infection occurred.

Clinical presentation and laboratory findings for the first autochthonous cases of dengue fever in Madeira island, Portugal, October 2012

An outbreak of dengue fever in Madeira island was reported in 2012. Clinical and laboratory findings of the first two laboratory-confirmed autochthonous cases are reported. Both cases had fever (≥38 °C) and petechial rash. Symptoms also included myalgia, asthenia, nausea, vomiting, anorexia, diffuse abdominal pain, and diarrhoea. The two cases were confirmed by serology and one tested positive for a dengue viral sequence. Dengue virus serotype DEN-1 was identified with probable Central or South American origin.

A review of the invasive mosquitoes in Europe: ecology, public health risks, and control options.

There has been growing interest in Europe in recent years in the establishment and spread of invasive mosquitoes, notably the incursion of Aedes albopictus through the international trade in used tires and lucky bamboo, with onward spread within Europe through ground transport. More recently, five other non-European aedine mosquito species have been found in Europe, and in some cases populations have established locally and are spreading. Concerns have been raised about the involvement of these mosquito species in transmission cycles of pathogens of public health importance, and these concerns were borne out following the outbreak of chikungunya fever in Italy in 2007, and subsequent autochthonous cases of dengue fever in France and Croatia in 2010. This article reviews current understanding of all exotic (five introduced invasive and one intercepted) aedine species in Europe, highlighting the known import pathways, biotic and abiotic constraints for establishment, control strategies, and public health significance, and encourages Europe-wide surveillance for invasive mosquitoes.

P1-341 Dengue spatial risk distribution in Campinas, Brazil

IntroductionDengue fever is an arboviruse of great importance in public health. Currently, the urban population modus vivendi favours transmission and maintenance of breeding sites of the vector, Aedes aegypti. Given...

Risk assessment of dengue virus amplification in Europe based on spatio-temporal high resolution climate change projections

During the last decades dengue incidences are emerging significantly around the globe. Currently, about one fifth of the human population lives in dengue risk zones, which are mainly located in (sub-) tropical regions of Southeast Asia and the Western Pacific. Dengue infections in European population mainly referred to returning travellers from tropical endemic regions. Nevertheless, vector establishment in Europe already took place and therefore the risk increases. Currendy, autochthonous cases of dengue fever have been reported in Europe. Studies estimating the risk of dengue epidemics regard ing changing climatic conditions in Europe are missing. Therefore, we close this gap by using the temperature constraints for virus amplification within the vector Aedes aegypti from two laboratory experiments. We transfer these findings to the changing European climate based on data provided from a regional climate model (COSMO-CLM; A1B and B1 scenario). Daily mean temperature were averaged for the time-steps 2011—2040, 2041—2070 and 2071-2100 in order to reduce natural variability but rather point out climatic trends for risk assessments. For both scenarios the strongest increase of temperature is projected after mid-century. Results indicate a growing threat of virus amplification in Europe especially towards the end of this century. Larger parts of the Mediterranean will be at risk. The southwest of the Iberian Peninsular appears to be especially threatened. Even in some parts of Central Europe, such as Southwest Germany, dengue virus amplification can no longer be excluded at the end of the century. However, it is unlikely that Aedes aegypti will serve as an efficient vector in Europe. In fact, it is Aedes albopictus that is an invasive species in Europe and potential differences in extrinsic incubation period between Ae. aegypti and Ae. albopictus have to be identified. Policy and public health authorities have to consider these emerging biorisks in order to establish surveillance systems and develop counteraction strategies. Hence, we strongly empha size the need for a growing European awareness in the face of biological hazards that are responding to climatic changes.

Modelo de risco tempo-espacial para identificação de áreas de risco para ocorrência de dengue

To apply the temporal-spatial model to assess high-risk areas for the occurrence of dengue fever. A total of 11,989 confirmed, autochthonous dengue fever cases, geocoded by address in the city of São José do Rio Preto (Southeastern Brazil), between September of 2001 and August of 2006, were included in the study. Frequency, duration and intensity indices were used to assess the severity and magnitude of transmission. The local indicator of spatial association was adopted to identify significant spatial clusters (p-value<0.05). The values of the three indices were considered high in a spatial unit when their standard values were positive and the respective local indicator of spatial association values were significant. Of all the geocoded dengue fever cases, 38.1% occurred in the urban spatial units, classified as highest-risk: 19.4% in 2001-2002, 13.9% in 2002-2003, 2.8% in 2003-2004, 16.7% in 2004-2005, and 21.3% in 2005-2006. The utilization of three risk measures enabled to identify higher-risk areas for the occurrence of dengue fever, concentrated in the city's northern region. Even though case notification data are subject to bias, this information is available in the health services and can lead to important conclusions, recommendations and hypotheses. The non-complex, notification-based procedures adopted in the study could be routinely used by services that are responsible for dengue fever surveillance and control to identify high-risk areas.