TABLE 4.
Data extracted from the systematic literature search conducted to identify studies reporting the percentage of inapparent CHIKV infections after a chikungunya epidemic in an initially CHIKV-naive populationa
| Identified study, yr (reference) | Yr of symptom collection | Outbreak location(s) | Virus lineageb | Responsible vector(s)b,c | % of CHIKV-positive participants (no. of CHIKV-positive participants/total no. of participants) | % of participants with inapparent infections (no. of participants with inapparent infections/total no. of CHIKV-positive participants)d | Sampling method |
|---|---|---|---|---|---|---|---|
| Gordon et al., 2018 (2014 children) (14)e | 2014 (during outbreak) | Managua, Nicaragua | Asian (likely) | A. aegypti (more likely) and A. albopictus (less likely) | 6.1 (204/3,361) | 54.5 (108/198) | Age stratified, systematic |
| Gordon et al., 2018 (2015 children)e (14) | 2015 (during outbreak) | Managua, Nicaragua | Asian (likely) | A. aegypti (more likely) and A. albopictus (less likely) | 21.3 (689/3,230) | 39.4 (254/645) | Age stratified, systematic |
| Cunha et al., 2017f (23) | 2016 (18 mo postoutbreak) | District of Chapada, Riachão do Jacuípe, Brazil | Non-IOL-strain ECSA (likely) | A. aegypti (likely) | 20.0 (24/120) | 45.8 (11/24) | Systematic, random |
| Bloch et al., 2016e (20) | 2014 (during outbreak) | Puerto Rico, USA | Asian (likely) | A. aegypti (likely) | 24.1 (56/232) | 37.5 (21/56) | Geographic (150 m around index cases’ homes) |
| Yoon et al., 2015g (24) | 2012–2013 (during outbreak) | Cebu City, Philippines | Asian | A. aegypti and A. albopictus (equally likely) | 12.5 (107/853) | 81.3 (87/107) | Age stratified, systematic |
| Srikiatkhachorn et al., 2016e (25) | 2013–2014 (during outbreak) | Cebu City, Philippines | Asian (likely) | A. aegypti and A. albopictus (equally likely) | 4.7 (21/443) | 71.4 (15/21) | Age stratified, systematic |
| Kuan et al., 2016 (adults)h (10) | 2016 (3 mo postoutbreak) | Managua, Nicaragua | Asian (likely) | A. aegypti (more likely) and A. albopictus (less likely) | 13.1 (111/848) | 64.9 (72/111) | Systematic, random |
| Galatas et al., 2016g (21) | 2012 (during outbreak) | Trapeang Roka, Cambodia | IOL strain ECSA (likely) | A. aegypti (likely) | 44.7 (190/425) | 5.3 (10/190) | Convenience (villagers available on day of investigation) |
| Gay et al., 2016 (26) | 2014 (during outbreak) | Saint Martin, France | Asian (likely) | A. aegypti (likely) | 20.7 (42/203) | 40.5 (17/42) | Convenience (laboratory clients) |
| Nakkhara et al., 2013 (22) | 2010–2011 (2 yr postoutbreak) | Thung Nari subdistrict, Pa Bon district, Thailand | IOL strain ECSA (likely) | A. albopictus (more likely) and A. aegypti (less likely) | 61.9 (314/507) | 47.1 (148/314) | Convenience (adults only) |
| Schwarz et al., 2012 (85) | 2010 (1–2 mo postoutbreak) | Mananjary and Manakaa, Madagascar | IOL strain ECSA (likely) | A. albopictus (more likely) and A. aegypti (less likely) | 32.3 (144/446) | 20.8 (30/144) | Convenience (pregnant women) |
| Ayu et al., 2010 (86) | 2007 (1 yr postoutbreak) | Bagan Panchor, Malaysia | Asian | A. aegypti and A. albopictus (equally likely) | 55.6 (40/72) | 17.5% (7/40) | Convenience (villagers who agreed to participate) |
| Sissoko et al., 2010 (87) | 2006 (9 mo after peak of outbreak) | Mayotte, France | IOL strain ECSA (likely) | A. albopictus (likely) | 38.1 (440/1,154) | 27.7 (122/440) | Multistage, cluster |
| Moro et al., 2010 (88) | 2007 (3–5 mo postoutbreak) | Castiglione di Cervia, Italy | IOL strain ECSA (likely) | A. albopictus (likely) | 10.2 (33/325) | 18.2 (6/33) | Age stratified, random |
| Manimunda et al., 2010 (89) | 2008 (during outbreak) | Dakshina Kannada District, Karnataka State, India | IOL strain ECSA (likely) | A. albopictus (likely) | 62.2 (224/360) | 6.3 (14/224) | Systematic, poststratified by age and sex |
| Leo et al., 2009 (90) | 2008 (during outbreak) | Singapore | IOL strain ECSA | A. aegypti (likely) | 0.5 (13/2,626) | 23.1 (3/13) | Geographic (150 m around index cases’ homes) |
| Gérardin et al., 2008 (91) | 2006 (1–3 mo postoutbreak) | La Réunion, France | IOL strain ECSA (likely) | A. albopictus (likely) | 39.6 (967/2,442) | 12.6 (116/921) | Multistage, random |
| Sergon et al., 2008f (27) | 2004 (2 mo after peak of outbreak) | Lamu Island, Kenya | IOL strain ECSA (likely) | A. aegypti (likely) | 75 (215/288) | 45.1 (97/215) | Multistage, random |
| Queyriaux et al., 2008i (30) | 2006 (during outbreak) | La Réunion, France | IOL strain ECSA (likely) | A. albopictus (likely) | 19.3 (128/662) | 3.1 (4/128) | Convenience (French soldiers) |
| Sergon et al., 2007 (92) | 2005 (during outbreak) | Grande Comore Island, Comoros | IOL strain ECSA (likely) | A. aegypti (likely) | 63.1 (209/331) | 14.4 (30/209) | Multistage, systematic |
| Retuya, 1998 (31) | 1996 (during outbreak) | Barangay Pulo, Indang, Cavite, Philippines | Unknown | A. aegypti and A. albopictus (equally likely) | 52.3 (156/298) | 23.1 (36/156) | Convenience (villagers who agreed to participate) |
A previous version of this table was used in another publication (93), from which the data were adapted with permission. Abbreviations: ECSA, East/Central/South African CHIKV lineage; IOL, Indian Ocean strain of the ECSA lineage.
The viral lineage responsible for the outbreak, when not explicitly confirmed through sequencing in the paper, was derived from other reported studies that genotyped virus isolates from either (i) the outbreak in question or (ii) e-mail correspondence with the study authors. Similarly, the responsible vector, when not explicitly confirmed through entomological investigation in the paper, was derived from either (i) the global compendium of Aedes aegypti and Aedes albopictus occurrence data set (82) or (ii) e-mail correspondence with the study authors. In these instances, the cell with the given information is labeled as “likely.”
When various Aedes species were circulating in the area of the epidemic (based on the text in the paper, correspondence with a study author, or the global Aedes occurrence compendium data set), the more populous subspecies was considered and labeled as “more likely” to be responsible for the epidemic, and vice versa.
Due to peculiarities in individual studies, the numerator of the “proportion of CHIKV-positive participants” column may not equal the denominator of the “proportion of inapparent infections” column.
Data in the study were supplemented by data provided by the first, senior, or corresponding author.
The proportion of inapparent infections was back-calculated from the reported proportion of symptomatic infections.
Data regarding the proportion of CHIKV-positive individuals or the proportion of inapparent infections were supplemented with data from another article reporting the same outbreak. (Data from Galatas et al. [21] were supplemented by data from Ly et al. [81], and data from Yoon et al. [24] were supplemented by data from Srikiatkhachorn et al. [25].)
The proportion of inapparent infections was back-calculated from the point estimate and/or the confidence interval and the assumed statistical distribution for the data, as per the cited study.
The numerator for the proportion of inapparent infections was back-calculated from the reported proportion of symptomatic infections and the sample size, as per the cited study.