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Volume 24, Number 9—September 2018
Letter

Seroprevalence of Chikungunya Virus after Its Emergence in Brazil

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To the Editor: In their well-designed and timely serosurvey, Dias et al. provide evidence of high prevalence of East/Central/South African (ECSA) genotype chikungunya virus (CHIKV) (seropositivity rate 51.0%) in population subsets of 2 urban communities in Bahia state, Brazil (1). The authors found a high proportion of asymptomatic CHIKV patients (63.2%; 268/424). In addition, the prevalence of chronic arthralgia among infected persons (26.4%; 112/424) was lower or within the expected range of previously reemerging clades of CHIKV, namely ECSA diverged (Indian Ocean lineage) or Asian lineage, respectively. However, a high proportion of the symptomatic participants in Dias et al. reported chronic symptoms lasting >3 months (71.8%; 112/156). We comment on these findings.

First, Dias et al. report that the selected locations were at the epicenter of the transmission area and, therefore, the data cannot be extrapolated to other cities. To better understand the dynamics of the disease, it would be useful to select locations more representative of other infected areas.

Second, the modest participation at the study locations (66.5%; 831/1250) could be related to using the more painful venipuncture method instead of a fingerstick to draw blood. In comparison, the participation rate was ≈80% in a Réunion Island serosurvey for CHIKV for which the fingerstick method was used (2). The participation level suggests the possibility of self-selection bias toward infected patients, who might be more interested in knowing their serologic status. Self-selection bias might explain the high proportion of symptomatic patients who self-reported having a chronic form of chikungunya.

Last, because of their unreliable discriminatory performance, using fever and arthralgia to identify symptomatic patients might have increased the proportion of patients misclassified as asymptomatic (i.e., patients with symptoms other than fever and arthralgia being falsely classified as negative) (3). These limitations being specified, the prevalence of chronic arthralgia among symptomatic patients in Dias et al. falls within the expected range of the Asian lineage of CHIKV, the other clade circulating in the Americas (4,5), which confers external validity to the study.

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Patrick Gérardin1Comments to Author , André Ricardo Ribas Freitas1, and Daouda Sissoko1

Author affiliations: Centre Hospitalier Universitaire Réunion, Saint Pierre, France (P. Gérardin); Unité Mixte 134 Processus Infectieux en Milieu Insulare Tropical, Sainte Clotilde, France (P. Gérardin); San Leopoldo Mandic School of Medicine, Campinas, Brazil (A.R.R. Freitas); Biomerieux Africa Cluster, Abidjan, Côte d’Ivoire (D. Sissoko)

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References

  1. Dias  JP, Costa  MDCN, Campos  GS, Paixão  ES, Natividade  MS, Barreto  FR, et al. Seroprevalence of chikungunya virus after its emergence in Brazil. Emerg Infect Dis. 2018;24:61724. DOIPubMed
  2. Gérardin  P, Guernier  V, Perrau  J, Fianu  A, Le Roux  K, Grivard  P, et al. Estimating Chikungunya prevalence in La Réunion Island outbreak by serosurveys: two methods for two critical times of the epidemic. BMC Infect Dis. 2008;8:99. DOIPubMed
  3. Sissoko  D, Ezzedine  K, Moendandzé  A, Giry  C, Renault  P, Malvy  D. Field evaluation of clinical features during chikungunya outbreak in Mayotte, 2005-2006. Trop Med Int Health. 2010;15:6007.PubMed
  4. Chang  AY, Encinales  L, Porras  A, Pacheco  N, Reid  SP, Martins  KAO, et al. Frequency of chronic joint pain following chikungunya virus infection: a Colombian cohort study. Arthritis Rheumatol. 2018;70:57884. DOIPubMed
  5. Paixão  ES, Rodrigues  LC, Costa  MDCN, Itaparica  M, Barreto  F, Gérardin  P, et al. Chikungunya chronic disease: a systematic review and meta-analysis. Trans R Soc Trop Med Hyg. 2018;112:30116. DOIPubMed

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Cite This Article

DOI: 10.3201/eid2409.180724

Original Publication Date: 7/31/2018

1All authors contributed equally to this article.

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Table of Contents – Volume 24, Number 9—September 2018

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Patrick Gérardin, INSERM CIC 1410 Clinical Epidemiology, Centre Hospitalier Universitaire, Groupe Hospitalier Sud Réunion, BP 350, 97448 Saint Pierre CEDEX, Reunion, France

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Page created: August 17, 2018
Page updated: August 17, 2018
Page reviewed: August 17, 2018
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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