The poor use bed nets less for malaria protection

Background: While recognizing the recent achievement in the global fight against malaria, the disease remains a challenge to health systems in low-income countries. Beyond widespread consensuses about prioritizing malaria prevention, little is known about the prevailing status of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) across different levels of wealth strata. The aim of this study was to evaluate the socioeconomic related dimension of inequalities in malaria prevention interventions.

Methods: This study was conducted in July–August 2014 in Adami Tullu district in the South-central Ethiopia, among 6069 households. A cross-sectional data were collected on household characteristics, LLIN ownership and IRS coverage. Principal component analysis technique was used for ranking households based on socioeconomic position. The inequality was measured using concentration indices and concentration curve. Decomposition method was employed in order to quantify the percentage contribution of each socioeconomic related variable on the overall inequality.

Results: The proportion of households with at least one LLIN was 11.6 % and IRS coverage was 72.5 %. The Erreygers normalized concentration index was 0.0627 for LLIN and 0.0383 for IRS. Inequality in LLIN ownership was mainly associated with difference in housing situation, household size and access to mass-media and telecommunication service.

Conclusion: Coverage of LLIN was low and significant more likely to be owned by the rich households, whereas houses were sprayed equitably. The current mass free distribution of LLINs should be followed by periodic refill based on continuous monitoring data.

Malaria in the Rift Valley in Ethiopia

Gari T, Kenea O, Loha E, Deressa W, Hailu A, Balkew M, Gebre-Michael T, Robberstad B, Overgaard HJ, Lindtjørn B: Malaria incidence and entomological findings in an area targeted for a cluster-randomized controlled trial to prevent malaria in Ethiopia: results from a pilot study. Malaria Journal 2016, 15.

Background  This study was part of the work to prepare for a cluster-randomized controlled trial to evaluate the effect of combining indoor residual spraying and long-lasting insecticidal nets on malaria incidence. A pilot study was done to estimate the variations of malaria incidence among villages, combined with entomological collections and an assessment of susceptibility to insecticides in malaria vectors.

Methods  A cohort of 5309 residents from four kebeles (the lowest government administrative unit) in 996 households was followed from August to December 2013 in south-central Ethiopia. Blood samples were collected by a finger prick for a microscopic examination of malaria infections. A multilevel mixed effect model was applied to measure the predictors of malaria episode. Adult mosquitoes were collected using light traps set indoors close to a sleeping person, pyrethrum spray sheet catches and artificial outdoor pit shelters. Enzyme-linked immunosorbent assays were used to detect the sources of mosquito blood meals, while mosquito longevity was estimated based on parity. The World Health Organization’s tube bioassay test was used to assess the insecticide susceptibility status of malaria vectors to pyrethroids and carbamates.

Results  The average incidence of malaria episode was 4.6 per 10,000 person weeks of observation. The age group from 5 to 14 years (IRR = 2.7; 95 % CI 1.1–6.6) and kebeles near a lake or river (IRR = 14.2, 95 % CI 3.1–64) were significantly associated with malaria episode. Only 271 (27.3 %) of the households owned insecticide-treated nets. Of 232 adult Anophelesmosquitoes collected, Anopheles arabiensis (71.1 %) was the predominant species. The average longevity of An. arabiensiswas 14 days (range: 7–25 human blood index days). The overall human blood index (0.69) for An. arabiensis was higher than the bovine blood index (0.38). Statistically significant differences in Anopheline mosquitoes abundance were observed between the kebeles (P = 0.001). Anopheles arabiensis was susceptible to propoxur, but resistant to pyrethroids. However, An. pharoensis was susceptible to all pyrethroids and carbamates tested.

Conclusions  This study showed a high variation in malaria incidence and Anopheles between kebeles. The observed susceptibility of the malaria vectors to propoxur warrants using this insecticide for indoor residual spraying, and the results from this study will be used as a baseline for the trial.

More malaria among wasted children

Shikur B, Deressa W, Lindtjørn B. Association between malaria and malnutrition among children aged under-five years in Adami Tulu District, south-central Ethiopia: a case–control study. BMC Public Health 2016; 16(1): 1-8.

Background: Malaria and malnutrition are the major causes of morbidity and mortality in under-five children in developing countries such as Ethiopia. Malnutrition is the associated cause for about half of the deaths that occur among under-five children in developing countries. However, the relationship between malnutrition and malaria is controversial still, and it has also not been well documented in Ethiopia. The aim of this study was to assess whether malnutrition is associated with malaria among under-five children.

Methods: A case–control study was conducted in Adami Tulu District of East Shewa Zone in Oromia Regional State, Ethiopia. Cases were all under-five children who are diagnosed with malaria at health posts and health centres. The diagnosis was made using either rapid diagnostic tests or microscopy. Controls were apparently healthy under-five children recruited from the community where cases resided. The selection of the controls was based on World Health Organization (WHO) cluster sampling method. A total of 428 children were included. Mothers/caretakers of under-five children were interviewed using pre-tested structured questionnaire prepared for this purpose. The nutritional status of the children was assessed using an anthropometric method and analyzed using WHO Anthro software. A multivariate logistic analysis model was used to determine predictors of malaria.

Results: Four hundred twenty eight under-five children comprising 107 cases and 321 controls were included in this study. Prevalence of wasting was higher among cases (17.8 %) than the controls (9.3 %). Similarly, the prevalence of stunting was 50.5 % and 45.2 % among cases and controls, respectively. Severe wasting [Adjusted Odds Ratio (AOR) =2.9, 95 % CI (1.14, 7.61)] and caretakers who had no education [AOR = 3, 95 % CI (1.27, 7.10)] were independently associated with malarial attack among under-five children.

Conclusion: Children who were severely wasted and had uneducated caretakers had higher odds of malarial attack. Therefore, special attention should be given for severely wasted children in the prevention and control of malaria.

Combining long-lasting insecticidal nets and indoor residual spraying for malaria prevention in Ethiopia: study protocol for a cluster randomized controlled trial

Wakgari-Trials-protocolDeressa W, Loha E, Balkew M, Hailu A, Gari T, Kenea O, Overgaard HJ, Gebremichael T, Robberstad B, and Lindtjørn B. Combining long-lasting insecticidal nets and indoor residual spraying for malaria prevention in Ethiopia: study protocol for a cluster randomized controlled trial. Trials 2016, 17:20

Background
Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the main malaria prevention interventions in Ethiopia. There is conflicting evidence that the combined application of both interventions is better than either LLINs or IRS used alone. This trial aims to investigate whether the combination of LLINs (PermaNet 2.0, Vestergaard Frandsen, Lausanne, Switzerland) with IRS using propoxur will enhance the protective benefits and cost-effectiveness of the interventions against malaria and its effect on mosquito behavior, as compared to each intervention alone.

Methods/Design
This 2 x 2 factorial cluster randomized controlled trial is being carried out in the Adami Tullu district in south-central Ethiopia for about 116 weeks from September 2014 to December 2016. The trial is based on four arms: LLINs + IRS, LLINs alone, IRS alone and control. Villages (or clusters) will be the unit of randomization. The sample size includes 44 clusters per arm, with each cluster comprised of approximately 35 households (about 175 people). Prior to intervention, all households in the LLINs + IRS and LLINs alone arms will be provided with LLINs free of charge. Households in the LLINs + IRS and IRS alone arms will be sprayed with carbamate propoxur once a year just before the main malaria transmission season throughout the investigation. The primary outcome of this trial will be a malaria incidence based on the results of the rapid diagnostic tests in patients with a fever or history of fever attending health posts by passive case detection. Community-based surveys will be conducted each year to assess anemia among children 5–59 months old. In addition, community-based malaria prevalence surveys will be conducted each year on a representative sample of households during the main transmission season. The cost-effectiveness of the interventions and entomological studies will be simultaneously conducted. Analysis will be based on an intention-to-treat principle.

Discussion
This trial aims to provide evidence on the combined use of LLINs and IRS for malaria prevention by answering the following research questions: Can the combined use of LLINs and IRS significantly reduce the incidence of malaria compared with the use of either LLINs or IRS alone? And is the reduced incidence justifiable compared to the added costs? Will the combined use of LLINs and IRS reduce vector density, infection, longevity and the entomological inoculation rate? These data are crucial in order to maximize the impact of vector control interventions on the morbidity and mortality of malaria.

Trial registration
PACTR201411000882128 (8 September 2014).

Highland malaria in Ethiopia

Abebe Animut Ayele defenAbebe [1]ds on Friday 15 January 2016 his PhD degree at the University of Bergen with a dissertation:

“Anopheles species and malaria transmission risk in a highland area, south-central Ethiopia.” 

Anopheles arabiensis is the primary malaria vector in the lowlands of Ethiopia. In the highland Butajira area, a typical area of highland Ethiopia, the entomological aspects of the disease remain poorly described.

The study describes the entomological aspects of malaria transmission by highlighting on the abundance, host feeding preferences, entomological inoculation rates (EIRs) and risk of households’ exposure to malaria infectious Anopheles bites over two years. The study was done at three different altitudes ranging from 1800 to 2300 m.

Ten species of larval stages and nine species of adult stages of anophelines occurred in the area. The streams were the main breeding habitats of the anophelines. Anopheles arabiensis was the most prevalent species, and was found to feed on human and cattle with a similar preference. Plasmodium falciparum and Plasmodium vivax infected Anopheles arabiensis and Plasmodium vivax infected Anopheles pharoensis were caught in the low- and mid-altitude villages. Also, houses with open eaves had higher density of malaria infectious Anopheles arabiensis.

Abebe Animut Ayele was born in 1968 in Gojjam in Ethiopia. He completed his bachelor’s degree in biology and his master’s degree in medical parasitology from Addis Ababa University where he works as a lecturer. He started his PhD training at the Centre for International Health, University of Bergen in 2008 with Professor Bernt Lindtjørn as main supervisor and Associate Professor Teshome Gebre-Michael as co-supervisor.

Abebe-coverThe thesis can be downloaded here 

The publications in his thesis include:

Animut A, Gebre-Michael T, Balkew M, Lindtjorn B. Abundance and dynamics of anopheline larvae in a highland malarious area of south-central Ethiopia. Parasit Vectors. 2012;5:117.

Animut A, Balkew M, Gebre-Michael T, Lindtjorn B. Blood meal sources and entomological inoculation rates of anophelines along a highland altitudinal transect in south-central Ethiopia. Malar J 2013; 12(1): 76.

Animut A, Balkew M, Lindtjorn B. Impact of housing condition on indoor-biting and indoor-resting Anopheles arabiensis density in a highland area, central Ethiopia. Malaria journal 2013;12(1):393.

Cattle and Control of Malaria

Massebo F, Balkew M, Gebre-Michael T, Lindtjorn B. Zoophagic behaviour of anopheline mosquitoes in southwest Ethiopia: opportunity for malaria vector control. Parasites & vectors 2015; 8(1): 645.

Background

Increased understanding of the feeding behaviours of malaria vectors is important to determine the frequency of human-vector contact and to implement effective vector control interventions. Here we assess the relative feeding preferences of Anopheles mosquitoes in relation to cattle and human host abundance in southwest Ethiopia.

Methods

We collected female Anopheles mosquitoes bi-weekly using Centers for Disease Control and prevention (CDC) light traps, pyrethrum spray catches (PSCs) and by aspirating from artificial pit shelters, and determined mosquito blood meal origins using a direct enzyme-linked immunosorbent assay (ELISA).

Results

Both Anopheles arabiensis Patton and An. marshalli (Theobald) showed preference of bovine blood meal over humans regardless of higher human population sizes. The relative feeding preference of An. arabiensis on bovine blood meal was 4.7 times higher than that of human blood. Anopheles marshalli was 6 times more likely to feed on bovine blood meal than humans. The HBI of An. arabiensis and An. marshalli significantly varied between the collection methods, whereas the bovine feeding patterns was not substantially influenced by collection methods. Even though the highest HBI of An. arabiensis and An. marshalli was from indoor CDC traps collections, a substantial number of An. arabiensis (65 %) and An. marshalli (63 %) had contact with cattle. Anopheles arabiensis (44 %) and An. marshalli (41 %) had clearly taken bovine blood meals outdoors, but they rested indoors.

Conclusion

Anopheles mosquitoes are zoophagic and mainly feed on bovine blood meals than humans. Hence, it is important to consider treatment of cattle with appropriate insecticide to control the zoophagic malaria vectors in southwest Ethiopia. Systemic insecticides like ivermectin and its member eprinomectin could be investigated to control the pyrethroid insecticides resistant vectors.

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.

Strengthening malaria and climate research in Ethiopia

Lindtjorn-Malaria conference posterLindtjorn B, Loha E, Deressa W, Balkew M, Gebremichael T, Sorteberg A, Woyessa A, Animut A, Diriba K, Massebo F, et al: Strengthening malaria and climate research in Ethiopia. Malaria Journal 2014, 13:P56.

Poster presentation

The project “Ethiopian Malaria Prediction System” implemented from 2007 to 2012 combined new population-based malaria transmission information with climate and land use variability data to develop an early warning tool to predict malaria epidemics in Ethiopia. Scientists from Ethiopia and Norway collaborated to incorporate climate variability and forecast information for malaria epidemics.

Our study shows that the association between weather and malaria is complex. Statistical models can predict malaria for large areas. However, as malaria transmission varies and depends on local environmental conditions, we need to have good and local knowledge about each area. However, weather variability is the main driver of malaria in Ethiopia.

While the generation of precipitation depends on local ascent and cooling of the air, our research provided new data on the transport of moisture into the country that may improve weather forecasting. We developed a new classification of climate zones, have mapped drought episodes in Ethiopia during the last decades, and have improved seasonal weather forecasting. Our hydrology studies show that potential climate change differs among the Ethiopian river basins, with river flows being sensitive to variations in rainfall, and less to temperature changes.

The computer model, Open Malaria Warning, incorporates hydrological, meteorological, mosquito-breeding, land-use data, and cattle densities to find out when and where outbreaks are likely to occur. We validated the model with data for malaria transmission in the highlands and lowlands, characterizing malaria transmission over some years in both highlands and lowlands. This provided us with new knowledge on malaria transmission in Ethiopia, how intense the seasonal transmission is, and how malaria occurs in different populations and areas. Our study showed that indigenous malaria transmission during a non-epidemic year takes place above 2000 m altitude. We also showed the ideal temperature for malaria transmission is about 25°C, underlining that global warming may lead to increased risk of malaria in highland areas, and less in the lowlands with already high average temperatures. However, to validate such models, there is a need for several years of active monitoring of malaria cases and mosquito densities. Unfortunately, such data is rare in Africa, and we need to invest in long-term monitoring of malaria transmission.

Lindtjorn-Malaria conference poster

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