Global transmission and evolutionary dynamics of the Chikungunya virus.

Chikungunya virus (CHIKV) is a re-emerging pathogen of global importance. We attempted to gain an insight into the organisation, distribution and mutational load of the virus strains reported from different parts of the world. We describe transmission dynamics and genetic characterisation of CHIKV across the globe during the last 65 years from 1952 to 2017. The evolutionary pattern of CHIKV was analysed using the E1 protein gene through phylogenetic, Bayesian and Network methods with a dataset of 265 sequences from various countries. The time to most recent common ancestor of the virus was estimated to be 491 years ago with an evolutionary rate of 2.78 × 10-4 substitutions/site/year. Genetic characterisation of CHIKV strains was carried out in terms of variable sites, selection pressure and epitope mapping. The neutral selection pressure on the E1 gene of the virus suggested a stochastic process of evolution. We identified six potential epitope peptides in the E1 protein showing substantial interaction with human MHC-I and MHC-II alleles. The present study augments global epidemiological and population dynamics of CHIKV warranting undertaking of appropriate control measures. The identification of epitopic peptides can be useful in the development of epitope-based vaccine strategies against this re-emerging viral pathogen.

Secondary Autochthonous Outbreak of Chikungunya, Southern Italy, 2017.

In 2017, a chikungunya outbreak in central Italy later evolved into a secondary cluster in southern Italy, providing evidence of disease emergence in new areas. Officials have taken action to raise awareness among clinicians and the general population, increase timely case detection, reduce mosquito breeding sites, and promote mosquito bite prevention.

Chikungunya Fever Outbreak, Zhejiang Province, China, 2017.

We report a disease outbreak caused by chikungunya virus in Zhejiang Province, China, in August 2017. Phylogenic analysis indicated that this virus belonged to the Indian Ocean clade of the East/Central/South African genotype and was imported by a traveler returning from Bangladesh.

Using Big Data to Monitor the Introduction and Spread of Chikungunya, Europe, 2017.

With regard to fully harvesting the potential of big data, public health lags behind other fields. To determine this potential, we applied big data (air passenger volume from international areas with active chikungunya transmission, Twitter data, and vectorial capacity estimates of Aedes albopictus mosquitoes) to the 2017 chikungunya outbreaks in Europe to assess the risks for virus transmission, virus importation, and short-range dispersion from the outbreak foci. We found that indicators based on voluminous and velocious data can help identify virus dispersion from outbreak foci and that vector abundance and vectorial capacity estimates can provide information on local climate suitability for mosquitoborne outbreaks. In contrast, more established indicators based on Wikipedia and Google Trends search strings were less timely. We found that a combination of novel and disparate datasets can be used in real time to prevent and control emerging and reemerging infectious diseases.

Spatial Dynamics of Chikungunya Virus, Venezuela, 2014.

Since chikungunya virus emerged in the Caribbean region in late 2013, ≈45 countries have experienced chikungunya outbreaks. We described and quantified the spatial and temporal events after the introduction and propagation of chikungunya into an immunologically naive population from the urban north-central region of Venezuela during 2014. The epidemic curve (n = 810 cases) unraveled within 5 months with a basic reproductive number of 3.7 and a radial spread traveled distance of 9.4 km at a mean velocity of 82.9 m/day. The highest disease diffusion speed occurred during the first 90 days, and space and space-time modeling suggest the epidemic followed a particular geographic pathway with spatiotemporal aggregation. The directionality and heterogeneity of transmission during the first introduction of chikungunya indicated existence of areas of diffusion and elevated risk for disease and highlight the importance of epidemic preparedness. This information will help in managing future threats of new or reemerging arboviruses.

East/Central/South African Genotype in a Chikungunya Outbreak, Dhaka, Bangladesh, 2017.

In 2017, an unprecedented increase in febrile illness was observed in Dhaka, Bangladesh. Real-time reverse transcription PCR confirmed that 603 (40.2%) of 1,500 cases were chikungunya fever. Phylogenetic analysis revealed circulation of the non-A226V East/Central/South African genotype of chikungunya virus in Bangladesh.

Clinical and Epidemiologic Patterns of Chikungunya Virus Infection and Coincident Arboviral Disease in a School Cohort in Haiti, 2014-2015.

BACKGROUND: Beginning in December 2013, an epidemic of chikungunya virus (CHIKV) infection spread across the Caribbean and into virtually all countries in the Western hemisphere, with >2.4 million cases reported through the end of 2017. METHODS: We monitored a cohort of school children in rural Haiti from May 2014, through February 2015, for occurrence of acute undifferentiated febrile illness, with clinical and laboratory data available for 252 illness episodes. RESULTS: Our findings document passage of the major CHIKV epidemic between May and July 2014, with 82 laboratory-confirmed cases. Subsequent peaks of febrile illness were found to incorporate smaller outbreaks of dengue virus serotypes 1 and 4 and Zika virus, with identification of additional infections with Mayaro virus, enterovirus D68, and coronavirus NL63. CHIKV and dengue virus serotype 1 infections were more common in older children, with a complaint of arthralgia serving as a significant predictor for infection with CHIKV (odds ratio, 16.2; 95% confidence interval, 8.0-34.4; positive predictive value, 66%; negative predictive value, 80%). CONCLUSIONS: Viral/arboviral infections were characterized by a pattern of recurrent outbreaks and case clusters, with the CHIKV epidemic representing just one of several arboviral agents moving through the population. Although clinical presentations of these agents are similar, arthralgias are highly suggestive of CHIKV infection.

Excess Mortality and Causes Associated with Chikungunya, Puerto Rico, 2014-2015.

During 2014-2015, a total of 31 deaths were associated with the first chikungunya epidemic in Puerto Rico. We analyzed excess mortality from various causes for the same months during the previous 4 years and detected 1,310 deaths possibly attributable to chikungunya. Our findings raise important questions about increased mortality rates associated with chikungunya.

Avaliação ecocardiográfica das alterações cardíacas tardias provocadas pela Febre Chikungunya / Echocardiographic evaluation of late cardiac abnormalitis caused by the Chikungunya Fever

Fundamento: A febre Chicungunya (CHIKV) provoca dores articulares altamente debilitantes. As complicações são raras, podendo afetar o sistema cardiovascular. Objetivo: Avaliar, com ecocardiografia e strain bidimensional, as alterações cardiovasculares na fase crônica da infecção por CHIKV. Métodos: Foram estudados 32 pacientes, média etária de 56 ± 14 anos, divididos em Grupo A, com evolução < 12 meses (12 pacientes) e Grupo B, com evolução ≥12 meses (20 pacientes). Foram determinadas as dimensões cardíacas, o volume diastólico final do ventrículo esquerdo indexado para superfície corporal; a fração de ejeção do ventrículo esquerdo, o strain longitudinal global do ventrículo esquerdo e o strain longitudinal do átrio esquerdo. Os grupos foram comparados pela análise não pareada. A significância de p foi < 0,05. Resultados: A maioria dos pacientes do Grupo A apresentou hipocontratilidade difusa e diminuição da fração de ejeção do ventrículo esquerdo (45,5 ± 10,4%) com com volume diastólico do ventrículo esquerdo indexado normal (58,7 ± 24,9 mL/m²). A maioria dos pacientes do Grupo B apresentou hipocontratilidade difusa (fração de ejeção do ventrículo esquerdo de 38,2 ± 6,4%) e volume diastólico do ventrículo esquerdo indexado aumentado (88,3 ± 26,4 mL/m²). Foram observadas alterações segmentares em 22% dos pacientes e hipertrofia ou remodelamento em 7 casos de cada Grupo. O strain longitudinal global estava diminuído (-11,9 ± 4,4% no Grupo A e -10,3 ± 3,8% no Grupo B). O strain longitudinal do átrio esquerdo foi de 37,9 ± 17,3% no Grupo A e de 27,5 ± 15,2% no Grupo B. Os pacientes com pericardite apresentavam dimensões e função do VE normais.Conclusão: Entre as complicações cardíacas da febre Chicungunya, a hipocontratilidade difusa com ventrículo esquerdo de dimensões normais foi observada no primeiro ano da evolução crônica e a hipocontratilidade difusa com dilatação do ventrículo esquerdo na evolução mais tardia. Pacientes com espessamento pericárdico não evidenciaram alterações miocárdicas. A ecocardiografia é uma importante ferramenta diagnóstica para os pacientes com infecção por vírus Chicungunya, pois detecta e quantifica as alterações do sistema cardiovascular

Background: Chicungunya fever causes highly debilitating joint pains. Complications are rare and may affect the cardiovascular system. Objective: To evaluate, with echocardiography and two-dimensional strain, the cardiovascular changes in the chronic phase of the Chikungunya infection. Methods: The study included 32 patients, mean age 56 ± 14 years divided into Group A, with < 12 months evolution (12 patients) and Group B, with ≥ 12 months evolution (20 patients). The cardiac dimensions, left ventricular end-diastolic volume indexed to body surface, left ventricular ejection fraction, left ventricular global longitudinal strain and left atrial longitudinal strain were determined. The groups were compared using unpaired analysis. The p significance was < 0.05. Results: Most Group A patients presented diffuse hypocontratility and decreased left ventricular ejection fraction (45.5 ± 10.4%) with normal left ventricular diastolic indexed volume (58.7± 24.9 mL/m²). Most Group B patients presented diffuse hypocontratility (ejection fraction 38.2 ± 6.4%) and increased left ventricular diastolic indexed volume (88.3 ± 26.4 mL/m²). There was segmental changes in 22% of the patients, and hypertrophy or remodelling in seven cases of each Group. There was decreased global longitudinal strain in both Groups (-11.9 ± 4.4% in Group A and -10.3 ± 3.8% in Group B). Lef atrial longitudinal strain were 37.9 ± 17.3% in Group A and 27.5 ± 15.2% in Group B. Patients with pericarditis had normal left ventricular dimensions and function. Conclusion: The cardiac complications of Chikungunya fever was diffuse hypocontratility with left ventricular normal size observed in the first year of chronic evolution and diffuse hypocontratility with left ventricular dilation observed in later evolution. Patients with pericardial thickening did not present myocardial issues. Echocardiography can be used as an important tool in patients with Chikungunya fever, since it can detects early abnormalities in the cardiovascular system

Seroprevalence of Dengue and Chikungunya Virus Antibodies, French Polynesia, 2014-2015.

We investigated dengue and chikungunya virus antibody seroprevalence in French Polynesia during 2014-2015. Dengue virus seroprevalence was ≈60% among schoolchildren and >83% among the general population; chikungunya virus seroprevalence was <3% before and 76% after Zika virus emergence (2013). Dengue virus herd immunity may affect Zika virus infection and pathogenesis.

Leaking Containers: Success and Failure in Controlling the Mosquito Aedes aegypti in Brazil.

In 1958, the Pan American Health Organization declared that Brazil had successfully eradicated the mosquito Aedes aegypti, responsible for the transmission of yellow fever, dengue fever, chikungunya, and Zika virus. Yet in 2016 the Brazilian minister of health described the situation of dengue fever as "catastrophic." Discussing the recent epidemic of Zika virus, which amplified the crisis produced by the persistence of dengue fever, Brazil's president declared in January 2016 that "we are in the process of losing the war against the mosquito Aedes aegypti." I discuss the reasons for the failure to contain Aedes in Brazil and the consequences of this failure. A longue durée perspective favors a view of the Zika epidemic that does not present it as a health crisis to be contained with a technical solution alone but as a pathology that has the persistence of deeply entrenched structural problems and vulnerabilities.

Imported Chikungunya Virus Strains, Taiwan, 2006-2014.

We identified 78 imported chikungunya cases in Taiwan during 2006-2014. Sixty-six (84.6%) cases were initially suspected to be dengue, which indicates the necessity for laboratory diagnostics in differentiation between dengue and chikungunya. Results also emphasize the need for active surveillance of febrile illness at points of entry.

Co-infections with Chikungunya and Dengue Viruses, Guatemala, 2015.

We screened serum samples referred to the national reference laboratory in Guatemala that were positive for chikungunya or dengue viruses in June 2015. Co-infection with both viruses was detected by reverse transcription PCR in 46 (32%) of 144 samples. Specimens should be tested for both arboviruses to detect co-infections.

Molecular Characterization of Chikungunya Virus, Philippines, 2011-2013.

During 2011-2013, a nationwide outbreak of chikungunya virus infection occurred in the Philippines. The Asian genotype was identified as the predominant genotype; sporadic cases of the East/Central/South African genotype were detected in Mindanao. Further monitoring is needed to define the transmission pattern of this virus in the Philippines.

Reconstruction of 60 Years of Chikungunya Epidemiology in the Philippines Demonstrates Episodic and Focal Transmission.

Proper understanding of the long-term epidemiology of chikungunya has been hampered by poor surveillance. Outbreak years are unpredictable and cases often misdiagnosed. Here we analyzed age-specific data from 2 serological studies (from 1973 and 2012) in Cebu, Philippines, to reconstruct both the annual probability of infection and population-level immunity over a 60-year period (1952-2012). We also explored whether seroconversions during 2012-2013 were spatially clustered. Our models identified 4 discrete outbreaks separated by an average delay of 17 years. On average, 23% (95% confidence interval [CI], 16%-37%) of the susceptible population was infected per outbreak, with >50% of the entire population remaining susceptible at any point. Participants who seroconverted during 2012-2013 were clustered at distances of <230 m, suggesting focal transmission. Large-scale outbreaks of chikungunya did not result in sustained multiyear transmission. Nevertheless, we estimate that >350 000 infections were missed by surveillance systems. Serological studies could supplement surveillance to provide important insights on pathogen circulation.

A Re-Examination of the History of Etiologic Confusion between Dengue and Chikungunya.

Contrary to the perception of many researchers that the recent invasion of chikungunya (CHIK) in the Western Hemisphere marked the first episode in history, a recent publication reminded them that CHIK had prevailed in the West Indies and southern regions of the United States from 1827-1828 under the guise of "dengue" (DEN), and that many old outbreaks of so-called "dengue" actually represented the CHIK cases erroneously identified as "dengue." In hindsight, this confusion was unavoidable, given that the syndromes of the two diseases-transmitted by the same mosquito vector in urban areas-are very similar, and that specific laboratory-based diagnostic techniques for these diseases did not exist prior to 1940. While past reviewers reclassified problematic "dengue" outbreaks as CHIK, primarily based on manifestation of arthralgia as a marker of CHIK, they neither identified the root cause of the alleged misdiagnosis nor did they elaborate on the negative consequences derived from it. This article presents a reconstructed history of the genesis of the clinical definition of dengue by emphasizing problems with the definition, subsequent confusion with CHIK, and the ways in which physicians dealt with the variation in dengue-like ("dengue") syndromes. Then, the article identifies in those records several factors complicating reclassification, based on current practice and standards. These factors include terms used for characterizing joint problems, style of documenting outbreak data, frequency of manifestation of arthralgia, possible involvement of more than one agent, and occurrence of the principal vector. The analysis of those factors reveals that while some of the old "dengue" outbreaks, including the 1827-1828 outbreaks in the Americas, are compatible with CHIK, similar reclassification of other "dengue" outbreaks to CHIK is difficult because of a combination of the absence of pathognomonic syndrome in these diseases and conflicting background information.