Students’ Field Research Project on Malaria: NIMR, the first line of defense

This article is the prosecution of “Students’ Field Research Project on Malaria: a modern plague“, outlining the key characteristics of malaria and its trasmission and the current protection measures studied by Louis-Georges Roumy¹, Niccolò Stomeo¹, Abu Elamin¹ Khattab Ayman ² and Seppo Meri^1,2 during their medical research experience.

^{1 Humanitas Institute, Milan, Italy
2 University of Helsinki, Finland}

Vector Control: The final step towards Malaria Eradication?

Written by Roumy Louis-Georges, Stomeo Niccolò, Elamin Abu, Hunimed Students

In the first two articles the origin of the project, the key characteristics of malaria and the current protection measures are presented.  Read the introduction and the following article.

NIMR: The first line of defense

Programs that aim to reduce malaria-related cases and deaths are defined as “control” programs. Malaria control involves two key factors: the first being the treatment of the disease while the other being preventive interventions. These two factors are employed simultaneously but their efficacy varies largely according to the level of transmission. The behaviour of the population in the affected area greatly influences the success of malarial management. Since the disease affects countries which are often not able to fully bear the economic burden caused by malaria, health workers in the public sector are underpaid and overworked. They lack the necessary equipment, drugs, training, and organisation. Due to this, it appears to be strategically wiser to implement vector control which is carried out by the following methods:

• Insecticide-treated nets (ITNs)
• Intermittent preventive treatment of malaria in pregnant women (IPTp)
• Intermittent preventive treatment of malaria in infancy (IPTi)
• Indoor residual spraying (IRS)
• Larval control and other vector control interventions

The National Institute for Medical Research (NIMR) is the largest public health research institution in Tanzania and has a long history of involvement in malarial research.

The Project Phases

NIMR was chosen for phase 2 of the project. While phase 1 of the project was carried out in Helsinki and entailed the design and development of the nets, phase 2 tested the efficacy of the 3D nets using standardised experimental huts in a local setting.

Although the second phase was carried out in Tanzania there was still a strong collaboration with Helsinki as researchers were sent over to oversee the project. For years the NIMR Muheza centre, located in North-Eastern Tanzania, has been actively developing and testing vector control methods in order to reduce the endemic. Focusing its activities on user-friendly insecticide-laced bed nets, affordable window screening and malarial research.

A very promising experiment is the implementation of double-screen windows in typical East-African housing. The objective is to prevent mosquitoes from spreading malaria both by averting new cases due to direct mosquito-human transmission but also to prevent mosquitoes from spreading the infection from an already infected human. If the method proves to be effective, low cost and widely accepted, it could drastically reduce the infection rate in East Africa as well as other African countries.

3D Screen Mosquito Traps: a Novel Method of Vector Control

The NIMR and the University of Helsinki, Finland, have been collaborating so as to test the efficacy of a novel innovative method of vector control. The solution developed by the University of Helsinki together with the Technical University of Tampere in Finland is a simple but effective mosquito double window-screen made of 3D nets with a gap of 5 cm between them. The double screen is designed so that it allows the entry of mosquitoes but restricts their exit. Therefore it serves as a mosquito trap which reduces vector contact by providing additional protection to the current insecticide-based malarial control interventions in the tropics (ITNs). Unfortunately insecticide-based approaches may turn ineffective in the long term due to the development of insecticide resistance in mosquitoes.

The effectiveness of the 3D screen mosquito traps was evaluated by these institutions by means of 6 experimental huts located in the vicinity of the NIMR Muheza center. At this point we were utilised along with a group of others. It was our responsibility to oversee the project and ensure that the correct protocols were being followed. Mosquitoes that were trapped are counted and classified by local entomologists (Anopheles gambiae, A. funestus, and a non-malarial vector A. culex). An important aspect is that the setting simulates local traditional houses, i.e houses that do not prevent mosquitoes from entering through eaves. 

Minimizing the level of bias

It must be noted that in order to gather the most accurate results it was necessary to reduce the level of bias to a minimum. Certain measures were put in place to ensure this, such as: a) the subjects in each house were rotated daily and b) the setting of each test house was changed weekly. By doing this, we reduced both the locational bias as well as the individual bias (as mosquitoes have a higher attraction for certain groups).

In order to obtain adequate results, the trapped mosquitoes were manually collected by entomologists at dawn. All female malarial vector species are stored for further identification and detection of malarial sporozoites by PCR techniques. The number of mosquitoes trapped after attempting a blood meal, depending on the experimental setting of the house, allowed for the best choice of  arrangement of the screens. The most efficient 3D screen configuration will be chosen based on mosquito trapping and the data collected.

Outcomes of the experiment

The 2 main outcomes of the experiment were as follows:

• Collecting mosquitos, which are eligible for further laboratory, statistical and epidemiological analyses.
• Proving that a specific arrangement of the 3D screen used does in fact lead to a decrease in transmission rates.

Want to know more about the project? In the final article you will read about:

• A viable approach to malarial eradication