[COTONOU, BENIN] Researchers in Benin say they have developed an improved method for detecting malaria parasites in mosquito vectors that could help yield better estimates of malaria transmission intensity in different settings.

The new technique detects and identifies the four Plasmodium species in the principal mosquito vectors, Anopheles gambiae and Anopheles funestus. It is also enables scientists to detect 'mixed' malaria infections where more than one type of Plasmodium parasite is present.

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Detects and identifies the four Plasmodium species, which could lead to better estimates of transmission intensity

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The study, published in PLOS ONE last month (28 December), explains that the technique optimises polymerase chain reaction (PCR) technology, a laboratory technique that amplifies and quantifies DNA molecules.

The researchers also say their method is more accurate than the traditional technique, which is based on the ELISA (enzyme-linked immunosorbent assay) test, a standard laboratory diagnostic test that uses antibodies and colour change to detect DNA molecules.

"This study presents an optimised method for detecting the four Plasmodium species in African malaria vectors," say the authors. They say it could be an "accurate molecular diagnostic tool for detecting malaria parasites in field mosquito populations".

Nicaise Tuikue Ndam, one of the authors of the study and a researcher at the University of Abomey-Calavi, Benin, tells SciDev.Net that ELISA measures a specific antigen that detects a single parasite. This older technique can lead to the overestimation of the malaria burden as the antigen used is not very specific.

"The new technique for the detection of parasites in malaria vectors can ensure a better, faster estimation of transmission intensity in different malaria settings," Ndam explains. "[It] has demonstrated a high analytical sensitivity in detecting mixed infections with distinct malaria-causing Plasmodium in the two main malaria vectors in Benin."

Augustin Koukpoliyi, supervisor of parasitology at the Hubert K. MAGA National Teaching Hospital of Cotonou (CHNU-HKM), who was not involved in the study, tells SciDev.Net: "The [new] method is a very important tool for malaria vaccine research".

"It enables us to know the genetic material of the parasite responsible for malaria transmission. If we do not know in detail the genetic material of the parasite, we will not be able to find a vaccine," he adds.

Link to full paper in PLoS ONE

References PLOS ONE doi:10.1371/journal.pone.0052719 (2012)