Poster GLOBVAC conference 2015

Entomological collections in areas targeted for a cluster randomized controlled trial to prevent malaria in Ethiopia: Results from a pilot study

Oljira Kenea1, Meshesha Balkew1, Teshome Gebre-Micheal1, Taye Gari2, Eskindir Loha2, Wakgari Deressa1,Alemayehu Dessalegn1, Bjarne Robberstad3, Hans J Overgaard4, Bernt Lindtjørn3

1 Addis Ababa University, Addis Ababa, Ethiopia.2HawassaUniversity, Hawassa, Ethiopia. 3University of Bergen, Bergen, Norway.4Norwegian University of Life Sciences, Ås, Norway.

Objective  Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) are the core malaria vector control tools in Ethiopia. Combining both in the same household as a vector control strategy is widespread but entomological outcomes of such interventions are little known. This pilot study was carried out to provide basic information about local malaria vector population for effective planning and implementation of IRS and LLINs cluster randomized trial.

Methodology  The study was conducted from June to October 2013 in Adami Tulu district, central Ethiopia. Indoor mosquito collections were done using CDC light traps and pyrethrum spray sheet catches. Outdoor collections were done from artificial pit shelters. Mosquitoes were identified to species by morphological characteristics and polymerase chain reaction (PCR). Enzyme-linked immunosorbent assays (ELISA) were carried out to detect the sources of host blood meals and circum-sporozoite proteins. Mosquito longevity was estimated using parity based on dilatation of ovarian tracheoles following dissection. Data were managed and analyzed using SPSS version 20.0 and a p value< 0.05 was considered to be statistically significant.

Results  All Anopheles gambiae mosquitoes were confirmed to be An. arabiensis by PCR. Of 232 adult Anopheles mosquitoes collected, An. arabiensis (71.1%) was the predominant species followed by An. pharoensis (21.1%). The overall average Anopheles density varied within and among the villages over the study months. All of the mosquitoes (n = 232) that were analyzed by ELISA were negative for Plasmodium falciparum and P. vivax circum-sporozoite proteins. The overall Human Blood Index (69.2%) for An. arabiensis was higher than Bovine Blood Index (38.4%) and it was higher for populations collected indoors (73%) than those collected outdoors (21%). Average longevity of An. arabiensis and An. pharoensis ranged from 7 to 25 and 1.6 to 6.3 days, respectively.

Conclusion  The density of An. arabiensis, the main malaria vector in Ethiopia, varied within and among the villages over the study months. This study provided preliminary information needed for effective planning and implementation of LLINs and IRS combined intervention trial against malaria in Adami Tulu district, central Ethiopia.

Poster on malaria at GLOBVAC 2015 conference

Malaria incidence in areas targeted for a cluster randomised controlled trial to prevent malaria in Ethiopia: Results from a pilot study

Taye Gari1, Eskindir Loha1, Wakgari Deressa 2, Alemayehu Hailu 2, Oljira Kenea 2, Meshesha Balkew2, Teshome Gebremichael 2, Bjarne Robberstad3, Hans J Overgaard 4,5, Bernt Lindtjørn 3
1 Hawassa University, Hawassa, Ethiopia. 2 Addis Ababa University, Addis Ababa, Ethiopia. 3University of Bergen, Bergen, Norway. 4Norwegian University of Life Sciences, Ås, Norway. 5 Institut de Recherche pour le Développement (IRD), MIVEGEC, Montpellier, France.

MalTrials project funded by RCN GLOBVAC, Norway (project no. 220554)

Objective  A cluster randomised controlled trial will be carried out in central Ethiopia to evaluate the effect of combining indoor residual spraying (IRS) and long-lasting insecticidal treated nets (LLIN) on reducing malaria incidence. A pilot study was conducted to assess the variation in malaria episodes within and among villages. Information from this pilot study will serve as the baseline and for calculation of a sufficient sample size to detect significant differences in malaria episode between study arms of the trial.

Method  A cohort of 5309 residents from 994 households in 29 villages were followed from August to December, 2013 in Adami Tulu district in central Ethiopia. The villages were selected based on average distance from Ziway lake shore where the majority of malaria mosquito breeding sites are located. A household census was done, followed by weekly home visits to collect malaria related data. Blood samples were taken from febrile patients. Microscopic slide examination was performed for malaria parasite identification. Incidence rate of malaria episodes was calculated.

Results  Only 271 (27.3%) of the households owned at least one insecticidal treated net at the start of the pilot study. The average proportion of residents sleeping under LLIN the night before the visit was 2.7%. Indoor residual spray was carried out in 901 (91.7%) households within one year before the visit. Of 349 persons examined 39(11.2%) were positive for malaria parasite. Plasmodium vivax was the dominant (84.6%) cause of malaria infection. The average incidence of malaria episode was 4.6 (varied among villages from 0 to 23.4 episodes) per 10,000 person weeks of observation. Higher malaria incidence was observed among children under 5, 5-14 years and in villages near the lake shore with 6.8, 6.3 and 8 episodes per 10,000 person weeks, respectively. The intra-cluster-correlation coefficient of malaria episodes was 0.27.

Conclusion  This pilot study showed that the incidence of malaria was higher in villages near the lake shore and in children less than 15 years old than the average incidence rate. The variation in malaria incidence between villages will be considered to calculate an appropriate sample size for the main trial.

Malaria Prevention trial

MalTrials-poster-Challenges in Malaria Research1Deressa W, Loha E, Balkew M, Desalegne A, Gari T, Gebremichael T, Kenea O, Jima D, Robberstad B, Overgaard H, Lindtjorn B: Combining long-lasting insecticidal nets and indoor residual spraying for malaria prevention in Ethiopia: study protocol for a cluster randomized controlled trial. Malaria Journal 2014, 13:P25.

Poster presentation

Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the two main malaria prevention strategies in Ethiopia. Although both interventions have been shown to be effective in reducing malaria transmission when applied independently, there is conflicting evidence that the two in combination is better than either one alone. The main objectives of this trial are to determine the added protection value against malaria and to evaluate the cost-effectiveness when applying IRS and LLINs together, or LLINs or IRS independently.

This trial will be conducted in Adami Tullu district of Oromia Regional State in Ethiopia from 2014 to 2016. The project will use a cluster randomized controlled trial, with four “arms”: IRS+LLINs, LLINs alone, IRS alone and control (routine practice). The sample size includes 40 clusters in each arm, each cluster with 35-45 households. Each household and each inhabitant in the household will be given a unique identification number. Households will be mapped using global positioning system. At the start of the trial, all households in the IRS+LLINs and LLINs alone “arms” of the study will be provided new LLINs free of charge. IRS with an insecticide (propoxur) will be applied in IRS+LLINs and IRS alone arms twice a year throughout the study.

Each household will be visited weekly, and blood samples will be collected from each household member with fever or history of fever. Thick and thin blood smears will be taken by finger prick and rapid diagnostic tests will be used to detect malaria at field level. Data on all self-reporting malaria patients attending health posts will be collected. The cost-effectiveness and entomological studies will be simultaneously conducted. Analysis will be based on intention to treat principle. Ethical clearance was obtained from the Ministry of Science and Technology in Ethiopia and the University of Bergen.

This trial aims to provide evidence on the combined use of IRS and LLINs for malaria prevention. We aim to answer the following research questions: Can the combined use of LLINs and IRS significantly reduce malaria incidence compared with the use of LLIN or IRS alone? And is the reduced incidence justifiably compared to the added costs? Will the combined use of LLINs and IRS reduce vector density, infection, longevity and the entomological inoculation rate? Such data is crucial in order to maximize the impact of the intervention on malaria morbidity and mortality.

MalTrials-poster-Challenges in Malaria Research


Update on MalTrials project

In January 2013 we finalised all agreements regarding the Norwegian Research Council grant regarding the MalTrials project: Combining indoor residual spraying and long-lasting insecticidal nets for preventing malaria: Cluster randomised trial in Ethiopia.

This note presents an update on the progress of the planned work:

  • Ethical clearance: We have applied for ethical permission to start the project, and we hope to get these permissions in July.
  • Once we get permission from Ethiopian authorities, we plan to start some pilot studies on:
    • Map the areas, and identify potential hot spots for malaria transmission
    • Select three kebeles (about 30 Gares, villages). We shall measure the incidence; find out the variation in incidence between the villages. This will enable us to calculate the correct sample size for our trial.
    • Start some entomological studies.
  • We have recruited three PhD students:
    • Taye Gari (epidemiology)
    • Alemayehu Desalegn (Health economics)
    • Oljira Kenea (Entomology)
  • We plan to start the main malaria trial in early 2014.



New malaria research programme in Ethiopia

We recently received the good news the Research Council of Norway will fund the project“Combining indoor residual spraying and long-lasting insecticidal nets for preventing malaria: Cluster randomised trial in Ethiopia”.

This research aims to improve malaria control by evaluating the combined effect of indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) on malaria incidence in Ethiopia. This project addresses how to promote uptake of research findings into public health programmes by enhancing our knowledge on interventions that will improve the effectiveness and coverage of malaria control programmes. It includes community randomised controlled trials to assess effectiveness of multiple interventions in combination versus one method alone within routine malaria control settings.

The clinical study objectives are to examine if IRS with insecticide and LLINs provide added protection against clinical malaria compared with LLINs alone. In the health economic part we shall estimate the costs of LLINs alone or combined with IRS, compared with current standard practice in the study settings. The study will also include studies on the anopheles mosquito where we aim to assess whether IRS with insecticide plus LLINs reduces vector biting and resting preference and density, longevity, infection and entomological inoculation rates inside houses when compared with LLIN alone.

We plan to start preliminary studies in late 2012, with start of the trial during the main malaria season in 2013. The planned study site is in the Adami Tullu area in the central part of the Rift valley in Ethiopia. This research will build up on the already established research collaboration between the University of Bergen, Addis Ababa University (School of Public Health and Aklilu Lemma Institute of Pathobiology), Hawassa University, and the Ethiopian Ministry of Health (Malaria Control).