Facilitating Dengue Vector Surveillance for Disease Control: A pilot study

Gulaiim Almatkyzy, M.S., John P. Grieco, Ph.D., Theeraphap Chareonviriyaphap, Ph.D., Sunny Shah, Ph.D., Nicole L. Achee, Ph.D.

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What would you say is the deadliest animal on Earth?

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Global Burden of Dengue

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Endemic in >100 countries; 390 million infections, 96 million clinical cases annually

Sources: 1. World Health Organization. (2017). Dengue and Severe Dengue. Retrieved from http://www.who.int/mediacentre/factsheets/fs117/en/2. HealthMap. (2018). Dengue Alerts for Past three months. Retrieved from http://www.healthmap.org/dengue/en/

Background: Dengue Virus

Mosquito-borne viral infection

Confirmed serotypes: DENV1-4 (DENV-5 is emerging)

Range of disease -asymptomatic to flu-like symptoms and severe, fatal disease

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Female Ae. aegypti mosquito in the process of acquiring a blood meal from her human host . Source: Centers for Disease Control and Prevention

Source: Mustafa, M. S., Rasotgi, V., Jain, S., & Gupta, V. (2015). Discovery of fifth serotype of dengue virus (DENV-5): A new public health dilemma in dengue control. Medical Journal Armed Forces India, 71(1), 67-70.

Dengue Vector Control Strategies

6Source: Achee ,N.L., Gould, F, Perkins, T.A., Reiner, R.C. Jr, Morrison, A.C., Ritchie, S.A., et al. (2015) A Critical Assessment of Vector Control for Dengue Prevention. PLoS NeglTrop Dis 9(5): e0003655. https://doi.org/10.1371/journal.pntd.0003655

Diagnostic Limitations

PCR

Expensive

Time consuming

Specialized laboratory

ELISA

Cross-reactivity

Seroprevelance only

PRNT

Expensive

Time consuming

Specialized laboratory

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Primary dengue infection with timing of diagnostic tests . Source: Tropical Regional Services, Queensland Health

Source: CDC. (2017). Laboratory Guidance and Diagnostic Testing. Retrieved from https://www.cdc.gov/dengue/clinicallab/laboratory.html

VecTOR dipstick

Immunochromatographic wicking dipstick assay

Works by antigen-antibody sandwich principle

Developed by VecTOR Test Systems

8Source: Wanja, et al., (2014). Immuno-chromatographic wicking assay for the rapid detection of dengue viral antigens in mosquitoes (Diptera: culicidae). Journal of Medical Entomology, 51(1), 220-225.

Testing VecTOR dipstick assay. Source: Personal Archive

Study Purpose

Goal

Improve dengue vector surveillance system at local level

Objective

Evaluate a rapid diagnostic tool to detect DENV in mosquitoes

Aims

Quantify the specificity and sensitivity of the VecTOR dipstick assay to detect DENV in field-collected mosquitoes and control samples

Assess the acceptability of the VecTOR distick assay among laboratory personnel via questionnaire

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Study Sites

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Nakhon Pathom Province,Sam Phran District

Bangkok Metropolis,Sai Mai district

Source: Maps of World. (2016). Thailand. Retrieved from https://www.mapsofworld.com/thailand/provinces/nakhon-pathom-map.html

Field Activities

Household selection

Indoor collection(A)

Purposive sampling

Prokopack aspirator

Outdoor collection (B)

Simple Random Sampling

BG-Sentinel traps

Mosquito storage

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Mosquito collection. Source: Personal Archive

Laboratory Test Work Flow

50 dipsticks

30 (pooled mosquitoes)

30 samples

4 (preliminary research)

16 (training)

8 positive control

8 negative control

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DENV Detection Summary

1306 total field-collected mosquitoes (61 households)

Site of collection Culex and Anopheles Aedes Female

Sai Mai district 57 7

Sam Phran district 947 260

KU campus 21 14

Total 1025 281

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Out of 281 pooled mosquitoes into 30 tubes

Sample Type PCR VecTOR dipstick

DENV+ (n=1) n=1 N=0

DENV- (n=29) n=29 N=29

DENV+ control samples (n=8) n=8 N=4

DENV- control samples (n=8) n=8 N=8

56.3% Cohens Kappa agreement between PCR and VecTOR dipstick

Questionnaire

Distributed to laboratory personnel

15 closed-ended questions

Three sections (5 questions each)

Ease-of-use

Practicality

Integration

Six-point Likert rating scale

0 (not applicable)

1 (strongly disagree)

5 (strongly agree)

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VecTOR dipstick assay training. Source: Personal Archive

4.2 4.2 44.6 4.6 4.8 4.4

54.4 4.47

42.8 3

3.83.2

3.8

3.2

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1.8

3.29

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2.6 2.8

3.6

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3.4

3.2

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2.2

3.2

user 1 user 2 user 3 user 4 user 5 user 6 user 7 user 8 user 9 average

Section Scores(VecTOR Dipstick)

Ease of Use Practicality Integration

Questionnaire Summary

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4.47 3.29 3.20

Summary

Goal of dengue surveillance systems is to control spread of virus within human populations

Dengue diagnostic tests are an essential component of disease surveillance and management systems - need for rapid, inexpensive, point-of-care tools with high sensitivity and specificity

VecTOR dipstick assay has potential as a user-friendly tool where capacity for PCR testing is limited: High specificity (100%) Fair sensitivity (44%) Considered easy to use

Practicality and integration were questionable

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Recommendations and Next Steps

Train other lab personnel and community members

Test in other regions (field-collected mosquitoes) - other flaviviruses and arboviruses to assess cross-reactivity

Larger sample size (for sensitivity and specificity)

Further research on practicality of the assay

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Acknowledgements Supervisor

Dr. Nicole L. Achee

In-Country Supervisor

Dr. Theeraphap Chareonviriyaphap

Committee members:

Dr. Sunny Shah

Dr. John Grieco

Special thanks:

Dr. Wunrada Surat

Ms. Flora Klacsmann

Ms. Amonrat Panthawong

Ms. Thikhumporn Sittivicharpinyo

Laboratory assistants:

Students from Department of Entomology, KasetsartUniversity

Students from Department of Genetics, KasetsartUniversity

Field assistants:

The Department of Environment, Saimai District, Bangkok Metropolis

The Department of Fishery Science, KasetsartUniversity

The Head Office of Sam Pran District, Nakhon PathomProvince

All community workers of Sam Pran District and Saimai District

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Thank You for Your Attention!

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