Category Archives: Malaria

More malaria among wasted children

Posted on by

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

Posted on by

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

Posted on by

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

Posted on by

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.

Malaria prevention trial

Posted on by

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

Strengthening malaria and climate research in Ethiopia

Posted on by

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

Ownership and use of long-lasting insecticidal nets for malaria prevention in Ethiopia

Posted on by

Woyessa A, Deressa W, Ali A, Lindtjorn B. Ownership and use of long-lasting insecticidal nets for malaria prevention in Butajira area, south-central Ethiopia: complex samples data analysis. BMC public health 2014; 14: 99.

BACKGROUND: Despite the encroaching of endemic malaria to highland-fringe areas above 2000 meters above sea level in Ethiopia, there is limited information on ownership and use of mosquito nets for malaria prevention. Thus, this study was designed to assess long-lasting insecticidal nets (LLIN) possession and use for malaria prevention in highland-fringe of south-central Ethiopia.

METHODS: A multi-stage sampling technique was employed to obtain household data from randomly selected households using household head interview in October and November 2008. Household LLIN possession and use was assessed using adjusted Odds Ratio obtained from complexsamples logistic regression analysis.

RESULTS: Only less than a quarter (23.1%) of 739 households interviewed owned LLINs with more differences between low (54.2%) high (3.5%) altitudes (Χ2 =253, P < 0.001). Higher LLIN ownership was observed in illiterate (adj.OR 35.1 [10.6-116.2]), male-headed (adj.OR 1.7 [1.051-2.89]), owning two or more beds (adj.OR 2.7 [1.6-4.6]), not doing draining/refilling of mosquito breeding sites (adj.OR 3.4 [2.1-5.5]) and absence of rivers or streams (adj.OR 6.4 [3.5-11.8]) of household variables. The presence of ≥2 LLINs hanging (adj.OR 21.0 [5.2-85.1]), owning two or more LLINs (adj.OR 4.8 [1.3-17.5]), not doing draining/refilling of mosquito breeding sites (adj.OR 4.2 [1.3-13.6]), low wealth status (adj.OR 3.55 [1.04-12.14]), and < 1 km distance from absence of rivers or streams (adj.OR 3.9 [1.2-12.1]) of households was associated with more likely use of LLIN. The LLIN ownership was low in the highlands, and most of the highland users bought the bed nets themselves.

CONCLUSIONS: This study found a low household LLIN ownership and use in the highland-fringe rural area. Therefore, improving the availability and teaching effective use of LLIN combined with removal of temporary mosquito breeding places should be prioritized in highland-fringe areas.

Screening houses prevents malaria

Posted on by

The results of this randomized trial show that screening doors and windows, and closing openings on walls and eves by mud reduced the overall indoor densities of An. arabiensis by 40%. Although screening intervention reduced indoor density of An. arabiensis at all abdominal stages, the reduction was substantially higher against unfed An. arabiensis. The intervention was based on locally bought materials, and was affordable.

 Massebo F, Lindtjorn B. The effect of screening doors and windows on indoor density of Anopheles arabiensis in south-west Ethiopia: a randomized trial. Malar J 2013; 12(1): 319.

Eskindir Loha defended his PhD thesis

Posted on by

On Tuesday September 3, 2013, Eskindir Loha defended his PhD thesis.

The title of the work is: “Variation in malaria transmission in southern Ethiopia: The impact of prevention strategies and a need for targeted intervention”.

Summary of Thesis

In Ethiopia, 60 per cent of the population is at risk of malaria. The transmission of the disease is unstable, and hence, the possibility of epidemics demanded continuous vigilance and preparedness of the health system. Meanwhile, the complexity of the transmission of the disease has become an impediment to retain the effectiveness of prevention and control strategies. Understanding factors that play role in disease transmission at different locations, the pattern of disease transmission, the impact of prevention and control strategies and challenges in control efforts were deemed crucial for the way forward.

This thesis analysed the local variations in the link between potential determinants of transmission – meteorological factors and malaria incidence. For this, we used datasets from 35 locations found in the Southern Nations and Nationalities People’s Region and registered within the period 1998 to 2007. The findings implied that the variability in the models to be principally attributed to regional differences, and a single model that fits all locations was not found. Although there is a biological link between meteorological factors and malaria transmission, the link is affected by local conditions and non-meteorological factors.

With the understanding of a need to incorporate non-meteorological factors, in an attempt to predict disease incidence, a detailed investigation was carried out in Chano Mille Kebele – one of the malarious Kebeles of Arba Minch Zuria district, Gamo Gofa zone, south Ethiopia. A prospective cohort study was conducted for two years with a weekly visit to each of 1,388 households. The findings showed that rainfall increased and indoor residual spraying with Deltamethrin reduced falciparum malaria incidence. Higher disease incidence was observed among males, children 5–14 years old, insecticide-treated net non-users, the poor, and people who lived closer to vector breeding site. Meanwhile, we identified spatio-temporal clusters of high disease rates within a 2.4 sq.km area of the Kebele.

Mass distribution of insecticide-treated nets neither showed community-wide benefit nor influenced the spatio-temporal clustering of malaria, though proved to be protective at the individual level. Further analysis on insecticide-treated nets showed that the proportion of insecticide-treated net use reached a maximum of 69 per cent despite a near universal coverage (98.4 per cent) was achieved. Sleeping under the insecticide-treated nets was influenced by gender, age and proximity to the vector breeding site. Factor compromising the usable life of insecticide-treated nets and a lack of convenient space to hang more than one net were reported.

The local variations in meteorology-malaria link, the heterogeneous risk carried by different population segments and the observed effect of prevention strategies may help to revisit the approaches towards malaria – for which I forwarded specific recommendations.