TY - JOUR
T1 - Integrated serological surveillance of acute febrile illness in the context of a lymphatic filariasis survey in Timor-Leste
T2 - A pilot study using dried blood spots
AU - Arkell, Paul
AU - Angelina, Julia
AU - do Carmo Vieira, Alberina
AU - Wapling, Johanna
AU - Marr, Ian
AU - Monteiro, Merita
AU - Matthews, Alexander
AU - Amaral, Salvador
AU - da Conceicao, Virginia
AU - Kim, Sung Hye
AU - Bailey, Daniel
AU - Yan, Jennifer
AU - Fancourt's, Nicholas S.S.
AU - Vaz Nery, Susana
AU - Francis, Joshua R.
N1 - Funding Information:
Funding: This work was supported by a Centres of Research Excellence Grant from the National Health and Medical Research Council, Australia (GNT1153727) and the Australian Government (Department of Foreign Affairs and Trade, agreement 74429).
Publisher Copyright:
© The Author(s) 2021. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.
PY - 2022/6/1
Y1 - 2022/6/1
N2 - BACKGROUND: Acute febrile illnesses (AFIs), including dengue, scrub typhus and leptospirosis, cause significant morbidity and mortality in Southeast Asia. Serological surveillance can be used to investigate the force and distribution of infections. Dried blood spot (DBS) samples are an attractive alternative to serum because they are easier to collect and transport and require less cold storage. We conducted a pilot study to determine the feasibility of integrating serological surveillance for dengue, scrub typhus and leptospirosis into a population-representative lymphatic filariasis seroprevalence survey in Timor-Leste using DBSs. METHODS: A total of 272 DBSs were collected from healthy community participants. DBSs were analysed at the National Health Laboratory using commercially available enzyme-linked immunosorbent assays. To validate assays for DBSs, 20 anonymised serum samples of unknown serostatus were used to create dried serum spots (DSSs). These were analysed with optical densities compared with those of serum. Where low variance was observed (dengue assay) the published kit cut-offs for serum were applied to the analysis of DBSs. For the other assays (scrub typhus and leptospirosis), index values (IVs) were calculated and cut-offs were determined to be at 2 standard deviations (SDs) above the mean. RESULTS: Of the 272 samples analysed, 19 (7.0% [95% confidence interval {CI} 4.3 to 10.7]) were positive for dengue immunoglobulin G (IgG), 11 (4.0% [95% CI 2.1 to 7.1]) were positive for scrub typhus IgG and 16 (5.9% [95% CI 3.4 to 9.4%]) were positive for leptospira IgG. CONCLUSIONS: While dengue seroprevalence was lower than in nearby countries, results represent the first evidence of scrub typhus and leptospirosis transmission in Timor-Leste. Integrated programmes of serological surveillance could greatly improve our understanding of infectious disease epidemiology in remote areas and would incur minimal additional fieldwork costs. However, when planning such studies, the choice of assays, their validation for DBSs and the laboratory infrastructure and technical expertise at the proposed location of analysis must be considered.
AB - BACKGROUND: Acute febrile illnesses (AFIs), including dengue, scrub typhus and leptospirosis, cause significant morbidity and mortality in Southeast Asia. Serological surveillance can be used to investigate the force and distribution of infections. Dried blood spot (DBS) samples are an attractive alternative to serum because they are easier to collect and transport and require less cold storage. We conducted a pilot study to determine the feasibility of integrating serological surveillance for dengue, scrub typhus and leptospirosis into a population-representative lymphatic filariasis seroprevalence survey in Timor-Leste using DBSs. METHODS: A total of 272 DBSs were collected from healthy community participants. DBSs were analysed at the National Health Laboratory using commercially available enzyme-linked immunosorbent assays. To validate assays for DBSs, 20 anonymised serum samples of unknown serostatus were used to create dried serum spots (DSSs). These were analysed with optical densities compared with those of serum. Where low variance was observed (dengue assay) the published kit cut-offs for serum were applied to the analysis of DBSs. For the other assays (scrub typhus and leptospirosis), index values (IVs) were calculated and cut-offs were determined to be at 2 standard deviations (SDs) above the mean. RESULTS: Of the 272 samples analysed, 19 (7.0% [95% confidence interval {CI} 4.3 to 10.7]) were positive for dengue immunoglobulin G (IgG), 11 (4.0% [95% CI 2.1 to 7.1]) were positive for scrub typhus IgG and 16 (5.9% [95% CI 3.4 to 9.4%]) were positive for leptospira IgG. CONCLUSIONS: While dengue seroprevalence was lower than in nearby countries, results represent the first evidence of scrub typhus and leptospirosis transmission in Timor-Leste. Integrated programmes of serological surveillance could greatly improve our understanding of infectious disease epidemiology in remote areas and would incur minimal additional fieldwork costs. However, when planning such studies, the choice of assays, their validation for DBSs and the laboratory infrastructure and technical expertise at the proposed location of analysis must be considered.
KW - dengue
KW - dried blood spot
KW - leptospirosis
KW - scrub typhus
KW - serological surveillance
KW - Timor-Leste
UR - http://www.scopus.com/inward/record.url?scp=85131221727&partnerID=8YFLogxK
U2 - 10.1093/trstmh/trab164
DO - 10.1093/trstmh/trab164
M3 - Article
C2 - 34850241
SN - 0035-9203
VL - 116
SP - 531
EP - 537
JO - Transactions of the Royal Society of Tropical Medicine and Hygiene
JF - Transactions of the Royal Society of Tropical Medicine and Hygiene
IS - 6
ER -
