Malaria Control In Ethiopia Research Articles

Resurgence of Clinical Malaria in Ethiopia in the Era of Anopheles stephensi Invasion.

The invasion of Anopheles stephensi into Africa poses a potential threat to malaria control and elimination on the continent. However, it is not clear if the recent malaria resurgence in Ethiopia has linked to the expansion of An. stephensi. We aimed to summarize the major achievements and lesson learnt in malaria control in Ethiopia from 2001 to 2022, to assess the new challenges and prospects for the control of An. stephensi. We obtained the clinical malaria case reports, antimalarial drug treatment records, insecticide-treated and long-lasting insecticidal net (ITN/LLIN) distribution and utilization records, and indoor residual spraying (IRS) coverage data from the Ethiopian Ministry of Health (MoH) for the period 2001-2022. We analyzed clinical malaria hotspots using spatially optimized hotspot analysis. We investigated malaria outbreaks in 2022 and examined the potential role of An. stephensi in the outbreaks.Clinical malaria cases in Ethiopia decreased by 80%, from 5.2 million cases (11% confirmed) in 2004 to 1.0 million cases (92% confirmed) in 2018; however, cases increased steadily to 2.6 million confirmed cases (98% confirmed) in 2022. Plasmodium vivax cases and proportion have increased significantly in the past 5 years. Clinical malaria hotspots are concentrated along the western Ethiopian border areas and have grown significantly from 2017 to 2022. Major malaria outbreaks in 2022/23 were detected in multiple sites across Ethiopia, and An. stephensi was the predominant vector in some of these sites, however, it was absence from many of the outbreak sites. The malaria burden has been significantly reduced in Ethiopia in the past two decades, but in recent years it has increased substantially, and the cause of such increase is a subject of further investigation. Major gaps exist in An. stephensi research, including vector ecology, surveillance, and control tools, especially for adult mosquito control.

Vivax malaria in Duffy-negative patients shows invariably low asexual parasitaemia: implication towards malaria control in Ethiopia

BackgroundThe increase in detections of Plasmodium vivax infection in Duffy-negative individuals in Africa has challenged the dogma establishing the unique P. vivax Duffy Binding Protein-Duffy antigen receptor for chemokines (PvDBP-DARC) pathway used by P. vivax merozoites to invade reticulocytes. Information on the impact of Duffy antigen polymorphisms on the epidemiology of P. vivax malaria remains elusive. The objective of this study was to determine the distribution of asexual parasitaemia of P. vivax according to the Duffy antigen polymorphisms in Ethiopia.MethodsDNA was extracted from dried blood spots (DBS) collected from prospectively recruited 138 P. vivax-infected patients from health centres. The identification and estimation of P. vivax asexual parasitaemia were performed by microscopic examination and quantitative real-time polymerase chain reaction (PCR). Duffy genotyping was conducted by DNA sequencing in a total of 138 P.vivax infected samples.ResultsThe proportion of Duffy-negatives (FY*BES/FY*BES) in P. vivax infected patients was 2.9% (4/138). Duffy genotype FY*B/FY*BES (48.6%) was the most common, followed by FY*A/FY*BES genotype (25.4%). In one patient, the FY*02 W.01/FY*02 N.01 genotype conferring a weak expression of the Fyb antigen was observed. All P.vivax infected Duffy-negative patients showed low asexual parasitaemia (≤ 110 parasites/µL). The median P. vivax parasitaemia in Duffy-negative patients (53 parasites/µL) was significantly lower than those found in homozygous and heterozygous individuals (P < 0.0001).ConclusionPlasmodium vivax in Duffy-negative patients shows invariably low asexual parasitaemia. This finding suggests that the pathway used by P. vivax to invade Duffy-negative reticulocytes is much less efficient than that used in Duffy-positives. Moreover, the low asexual parasitaemia observed in Duffy-negative individuals could constitute an ‘undetected silent reservoir', thus likely delaying the elimination of vivax malaria in Ethiopia.

Modeling reservoir management for malaria control in Ethiopia

This study investigated how changes in reservoir water level affect mosquito abundance and malaria transmission in Ethiopia. Digital elevation models of three Ethiopian dams at lowland, midland and highland elevations were used to quantify water surface area and wetted shoreline at different reservoir water levels (70, 75, 80, 85, 90, 95 and 100% full capacity) to estimate surface area of potential mosquito breeding habitat. Reservoir water level drawdown rates of 10, 15 and 20 mm.day−1 were applied as scenarios to model larval abundance, entomological inoculation rate (EIR) and malaria prevalence at each dam. Malaria treatment cost and economic cost in terms of lost working days were calculated for each water level scenario and dam. At the lowland dam, increased larval abundances were associated with increasing reservoir water level and wetted shoreline area. In contrast, both larval abundances and area of wetted shoreline declined with increasing reservoir water level at the midland and highland dams. Estimated EIR, malaria prevalence, malaria treatment cost and economic cost generally decreased when the water level drawdown rate increased from 10 to 15 and 20 mm.day−1 irrespective of reservoir water level. Given the expansion of dam construction in sub-Saharan Africa, incorporating malaria control measures such as manipulating drawdown rates into reservoir management has the potential to reduce the malaria burden and health care costs in communities near reservoirs.

Determination of the residual efficacy of carbamate and organophosphate insecticides used for indoor residual spraying for malaria control in Ethiopia

BackgroundIndoor residual spraying is one of the key vector control interventions for malaria control in Ethiopia. As malaria transmission is seasonal in most parts of Ethiopia, a single round of spraying can usually provide effective protection against malaria, provided the insecticide remains effective over the entire malaria transmission season. This experiment was designed to evaluate the residual efficacy of bendiocarb, pirimiphos-methyl, and two doses of propoxur on four different wall surfaces (rough mud, smooth mud, dung, and paint). Filter papers affixed to wall surfaces prior to spraying were analyzed to determine the actual concentration applied. Cone bioassays using a susceptible Anopheles arabiensis strain were done monthly to determine the time for which insecticides were effective in killing mosquitoes.ResultsThe mean insecticide dosage of bendiocarb applied to walls was 486 mg/m2 (target 400/mg). This treatment lasted 1 month or less on rough mud, smooth mud, and dung, but 4 months on painted surfaces. Pirimiphos-methyl was applied at 1854 mg/m2 (target 1000 mg/m2), and lasted between 4 and 6 months on all wall surfaces. Propoxur with a target dose of 1000 mg/m2 was applied at 320 mg/m2, and lasted 2 months or less on all surfaces, except painted surfaces (4 months). Propoxur with a target dose of 2000 mg/m2, was applied at 638 mg/m2, and lasted 3 months on rough mud, but considerably longer (5–7 months) on the other substrates.ConclusionsIt would appear that the higher dose of propoxur and pirimiphos-methyl correspond best to the Ethiopian transmission season, although interactions between insecticide and the substrate should be taken into account as well. However, the insecticide quantification revealed that the dosages actually applied differed considerably from the target dosages, even though care was taken in the mixing of insecticide formulations and spraying of the walls. It is unclear whether this variability is due to initial concentrations of insecticides, poor application, or other factors. Further work is needed to ensure that target doses are correctly applied, both operationally and in insecticide evaluations.

Transmission dynamics of co-endemic Plasmodium vivax and P. falciparum in Ethiopia and prevalence of antimalarial resistant genotypes.

Ethiopia is one of the few African countries where Plasmodium vivax is co-endemic with P. falciparum. Malaria transmission is seasonal and transmission intensity varies mainly by landscape and climate. Although the recent emergence of drug resistant parasites presents a major issue to malaria control in Ethiopia, little is known about the transmission pathways of parasite species and prevalence of resistant markers. This study used microsatellites to determine population diversity and gene flow patterns of P. falciparum (N = 226) and P. vivax (N = 205), as well as prevalence of drug resistant markers to infer the impact of gene flow and existing malaria treatment regimes. Plasmodium falciparum indicated a higher rate of polyclonal infections than P. vivax. Both species revealed moderate genetic diversity and similar population structure. Populations in the northern highlands were closely related to the eastern Rift Valley, but slightly distinct from the southern basin area. Gene flow via human migrations between the northern and eastern populations were frequent and mostly bidirectional. Landscape genetic analyses indicated that environmental heterogeneity and geographical distance did not constrain parasite gene flow. This may partly explain similar patterns of resistant marker prevalence. In P. falciparum, a high prevalence of mutant alleles was detected in codons related to chloroquine (pfcrt and pfmdr1) and sulfadoxine-pyrimethamine (pfdhps and pfdhfr) resistance. Over 60% of the samples showed pfmdr1 duplications. Nevertheless, no mutation was detected in pfK13 that relates to artemisinin resistance. In P. vivax, while sequences of pvcrt-o were highly conserved and less than 5% of the samples showed pvmdr duplications, over 50% of the samples had pvmdr1 976F mutation. It remains to be tested if this mutation relates to chloroquine resistance. Monitoring the extent of malaria spread and markers of drug resistance is imperative to inform policy for evidence-based antimalarial choice and interventions. To effectively reduce malaria burden in Ethiopia, control efforts should focus on seasonal migrant populations.

Policy brief on improving access to artemisinin-based combination therapies for malaria control in Ethiopia

Malaria in Ethiopia is one of the leading causes of death (21.8 percent), consultation in outpatient departments (17.8 percent) and hospital admissions (14.1 percent) (2;14). To overcome this problem, the Malaria Control Program (Federal Ministry of Health) has designed a community-based malaria treatment approach that played key roles in malaria epidemic control and community mobilization as well as vector control operations. In this approach, Community Health Workers (CHWs) and Village Malaria Workers, volunteers selected by community and trained on malaria diagnosis and treatment as well as indoor residual spray for few days (16). However, sustainability of this approach has been a challenge to the malaria control program. Thus, institutional arrangements in which every Kebele (the smallest administrative unit of 5,000 people) has a health post staffed by two Health Extension Workers (HEW) as part of the country's health system is a breakthrough to strengthen malaria control. A study has shown that more than half of the patients with fever visit CHWs and private health facility services (4).

Baseline survey for the implementation of insecticide treated mosquito nets in Malaria control in Ethiopia

Abstract Background: Insecticide treated mosquito nets (ITNs) have raised a renewed interest to serve as tools for malaria control in Africa. The use of this control method has been proved to be a cost-effective means for the control of malaria. However, little is known the acceptability and utilization of mosquito nets in Ethiopia. Objectives: The objective of this study is to provide relevant information about the knowledge, attitude and experience of communities about malaria and its preventive methods, particularly the acceptability and affordability of ITNs. Methods: A descriptive cross-sectional study was carried out in five different parts of Ethiopia in January and February 1999. A multi-stage sampling method was used to select 1,933 households for the study. Data were collected by interviewing household heads or their representatives. Results: Ninety-five percent of the participants perceived fever, headache and chilling of the body as the main symptoms of malaria. More than 87% of the interviewees correctly identified the names of the anti-malarial drugs, chloroquine and SP. About 93% of the participants knew that malaria could be transmitted through mosquito bites. Mosquitoes are known to breed on stagnant water (83%). More than 43% of the respondents replied that DDT, in combination with other control measures, could prevent malaria. Forty-one percent of the respondents had heard about the mosquito net. Only 5.3% of the respondents in the survey reported the presence of at least one mosquito net in their households. Most of the respondents (92.5%) were interested in using mosquito nets sometime in the future. The most preferred mode of obtaining ITNs was on loan basis (60%). Accordingly, 24%, 20% and 16% were willing to pay in three, six, and nine months of installments and above, respectively. Forty-percent of the study participants were ready to buy it in cash. Of the 1,696 respondents, 47% suggested 10 Birr or less, 11% between 11 and 20 Birr, 28% from 2150 Birr and the rest (14%) mentioned 51 Birr and above as the appropriate price for purchasing a single ITN. Conclusion: The utilization of mosquito nets at the time of the study was very low. However, acceptability and willingness to use ITNs for malaria prevention was very high. Thus, the expanding ITN implementation and increasing its coverage for malaria control both in urban and rural malarious areas of the country is crucial. It is recommended that communities should be strongly sensitized on the importance of ITNs for malaria control and the availability and affordability should be insured. [Ethiop.J.Health Dev. 2005;19(1):16-23]