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Identification of Plasmodium falciparum infection in mosquitoes using Near infrared spectroscopy

Applicant Ferreira Maia Marta
Number 181590
Funding scheme Marie Heim-Voegtlin grants
Research institution Abt. öff. Gesundheitswesen und Epidemiologie Schweizerisches Tropen- und Public Health-Institut
Institution of higher education University of Basel - BS
Main discipline Infectious Diseases
Start/End 01.08.2018 - 31.10.2018
Approved amount 29'028.00
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All Disciplines (2)

Discipline
Infectious Diseases
Methods of Epidemiology and Preventive Medicine

Keywords (6)

Plasmodium falciparum; malaria; surveillance; Anopheles gambiae; Africa; near-infrared spectroscopy

Lay Summary (German)

Lead
Identifizierung von Plasmodium falciparum Infektion in Stechmuecken
Lay summary

Malaria ist eine Krankheit, die durch Mücken auf Menschen übertragen wird. Obschon die Mückenbekämpfung in den letzten Jahren die Malariafälle stark reduziert hat, bleibt die Krankheit eine der Haupttodesursachen bei Kindern in Subsahara-Afrika. Um Malaria zu eliminieren, braucht es einerseits neue Wege, um die Krankheit zu bekämpfen und andererseits neue Wege, um deren Ausbreitung und Transmissionsintensität zu überwachen.

Nahinfrarotspektroskopie (NIRS) ist eine neue Methode, welche Spektroskopie und maschinelles Lernen kombiniert, um Proben mit Hilfe einer Kalibrierung, die auf einem Übungs-Datensatz basiert, zu unterteilen. Dieser Ansatz zeigte eine Genauigkeit von 97 % in der Vorhersage des Infektionsstatus von gezüchteten Mücken, die mit kultivierten Parasiten infiziert wurden. Das aktuelle Projekt wird auf der bisher geleisteten Arbeit aufbauen und die Methode mit Proben aus Kenia validieren. Mücken von der Küstenregion in Kenia werden unter kontrollierten Bedingungen mit Malaria infiziert. Dabei werden die Mücken mit Blut gefüttert, das von lokalen Dorfbewohnern stammt, die positiv auf Malaria getestet wurden. Anschliessend werden die Mücken zwei Wochen lang in einem sicheren Insektarium gehalten, damit sich der Parasit entwickeln kann. Danach werden die Mücken getötet und deren Infektionsstatus mit NIRS bestimmt. Genauigkeit, Spezifität und Sensitivität werden dokumentiert.

Durch die Abnahme von Malariafällen, sinkt auch die Infektionsrate  bei den Mücken. Dies erfordert eine Hochdurchsatzmethode, um Malaria in der Vektorpopulation nachzuweisen. Die Entwicklung von NIRS zum Nachweis von Parasiten in der Vektorpopulation kann einen grossen Einfluss darauf haben, wie Malaria in der Mückenpopulation überwacht wird.


 
Direct link to Lay Summary Last update: 15.06.2018

Responsible applicant and co-applicants

Employees

Publications

Publication
Detection of Plasmodium falciparum infected Anopheles gambiae using near-infrared spectroscopy
Maia Marta F., Kapulu Melissa, Muthui Michelle, Wagah Martin G., Ferguson Heather M., Dowell Floyd E., Baldini Francesco, Ranford-Cartwright Lisa (2019), Detection of Plasmodium falciparum infected Anopheles gambiae using near-infrared spectroscopy, in Malaria Journal, 18(1), 85-85.

Datasets

Replication Data for: Near infrared spectra and calibration for detection of malaria infection in Anopheles gambiae (Keele strain)

Author Ferreira Maia, Marta; Kapulu, Melissa; Muthui, Michelle; Wagah, Martin; Ferguson, Heather; Dowell, Floyd; Baldini, Francesco
Publication date 14.12.2018
Persistent Identifier (PID) doi:10.7910/DVN/YD34OX
Repository Harvard Dataverse
Abstract
Anopheles gambiae (Keele Strain) mosquitoes were infected in the lab with cultured Plasmodium falciparum gametocytes (PfN54) to generate oocyst and sporozoite infected vectors. Controls, uninfected mosquitoes, were generated by feeding mosquitoes on the same blood after gametogenesis had occurred which was triggered by dropping the temperature in the glass feeders to below 30 degrees Celsius. After feeding, mosquitoes were kept for 7 and 14 days to allow parasite development after which each individual mosquito was scanned with near infrared spectroscopy (NIRS) and stored at -20 until processed by qPCR (quantitative polymerase chain reaction) for confirmation of infection and quantification of parasite load. The data shared is composed of all the spectra that were collected (in .spc format for GRAMS IQ software) labeled with a unique identifier which links to the STATA files where the mean number of parasite genomes and age for each individual mosquito are listed. The files used to generate the calibration through partial least square (PLS) regression on GRAMS IQ have also been shared (.tfdx) along with the calibration file (.cal) for uploading on IQ Predict software. We have also shared the prediction outputs of the independent samples that were predicted with the calibrations here developed.

Associated projects

Number Title Start Funding scheme
164444 Evaluating near-infrared technology (NIRS) for identification of malaria infected mosquitoes as a tool for malaria control programs in sub-Saharan Africa 01.08.2016 Marie Heim-Voegtlin grants

Abstract

This proposal requests a follow-up grant for an ongoing study (PMPDP3_164444) investigating if near-infrared spectroscopy (NIRS) can detect Plasmodium falciparum infection in mosquitoes. The technology offers an opportunity for the development of a high throughput testing method which would benefit malaria surveillance programs. So far, I have infected mosquitoes in the lab and collected spectra from both uninfected and infected mosquitoes up to oocyst and sporozoite stage. I have determined infection load of each mosquito samples with qPCR and analyzed the spectra data using cross-validations. I can conclude that NIRS can be used to accurately predict Pl. falciparum sporozoite infection in Anopheles gambiae s.s with over 90% sensitivity and specificity independent of infection load. However, the earlier stages of infection in mosquitoes (oocyst stage) did not provide discernable results, cross validations showed that the NIRS spectra between infected and uninfected mosquitoes were not sufficiently different to tell them apart. Although the results for sporozoite-infected mosquitoes are very promising, the method must still be validated using samples from infections closer to what would be found in the wild. I am in Kenya preparing for this stage of the project. I have received all regulatory approvals needed for the study and community engagement in Kilifi has begun; screening for participants will be done following the on-start of the long rains from mid-April to July. The recruited participants will be asked to donate blood to infect mosquitoes in the lab and a few volunteers will be asked to feed the mosquitoes directly on their arms. Mosquitoes will be allowed to develop parasitic infections up to sporozoite stage after which they will be killed and scanned using NIRS. The spectra collected will be used to validate the calibrations previously generated. Screening has not yet begun because prevalence of asymptomatic carriers in the dry season is expected to be very low. To ensure that the project can reach its objectives and recruit its target number of participants for mosquito feeding assays it is advisable to concentrate field activities following the long rains in order not to exhaust the research funds available before reaching the recruitment target. My current fellowship is scheduled to end in July, the additional funds requested in this follow up proposal would allow me enough time to conclude the field work, summarize and disseminate the main findings
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