NRU :: Browsing by Author "Echodu, Richard"

Browsing by Author "Echodu, Richard"

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Analysis of Multiple Tsetse Fly Populations in Uganda Reveals Limited Diversity and Species-Specific Gut Microbiota
(Applied and Environmental Microbiology, 2014) Aksoy, Emre; Telleria, Erich L.; Echodu, Richard; Wu, Yineng; Okedi, Loyce M.; Weiss, Brian L.; Aksoy, Serap; Caccone, Adalgisa
The invertebrate microbiome contributes to multiple aspects of host physiology, including nutrient supplementation and immune maturation processes. We identified and compared gut microbial abundance and diversity in natural tsetse flies from Uganda using five genetically distinct populations of Glossina fuscipes fuscipes and multiple tsetse species (Glossina morsitans morsitans, G. f. fuscipes, and Glossina pallidipes) that occur in sympatry in one location. We used multiple approaches, including deep sequencing of the V4 hypervariable region of the 16S rRNA gene, 16S rRNA gene clone libraries, and bacterium-specific quantitative PCR (qPCR), to investigate the levels and patterns of gut microbial diversity from a total of 151 individuals. Our results show extremely limited diversity in field flies of different tsetse species. The obligate endosymbiont Wigglesworthia dominated all samples (>99%), but we also observed wide prevalence of low-density Sodalis (tsetse’s commensal endosymbiont) infections (<0.05%). There were also several individuals (22%) with high Sodalis density, which also carried coinfections with Serratia. Albeit in low density, we noted differences in microbiota composition among the genetically distinct G. f. fuscipes flies and between different sympatric species. Interestingly, Wigglesworthia density varied in different species (104 to 106 normalized genomes), with G. f. fuscipes having the highest levels. We describe the factors that may be responsible for the reduced diversity of tsetse’s gut microbiota compared to those of other insects. Additionally, we discuss the implications of Wigglesworthia and Sodalis density variations as they relate to trypanosome transmission dynamics and vector competence variations associated with different tsetse species.
Analysis of the gut-specific microbiome from field-captured tsetse flies, and its potential relevance to host trypanosome vector competence
(BMC microbiology, 2018) Griffith, Bridget C.; Weiss, Brian L.; Aksoy, Emre; Mireji, Paul O.; Auma, Joana E.; Wamwiri, Florence N.; Echodu, Richard; Murilla, Grace; Aksoy, Serap
The tsetse fly (Glossina sp.) midgut is colonized by maternally transmitted and environmentally acquired bacteria. Additionally, the midgut serves as a niche in which pathogenic African trypanosomes reside within infected flies. Tsetse’s bacterial microbiota impacts many aspects of the fly’s physiology. However, little is known about the structure of tsetse’s midgut-associated bacterial communities as they relate to geographically distinct fly habitats in east Africa and their contributions to parasite infection outcomes. We utilized culture dependent and independent methods to characterize the taxonomic structure and density of bacterial communities that reside within the midgut of tsetse flies collected at geographically distinct locations in Kenya and Uganda. Results: Using culture dependent methods, we isolated 34 strains of bacteria from four different tsetse species (G. pallidipes, G. brevipalpis, G. fuscipes and G. fuscipleuris) captured at three distinct locations in Kenya. To increase the depth of this study, we deep sequenced midguts from individual uninfected and trypanosome infected G. pallidipes captured at two distinct locations in Kenya and one in Uganda. We found that tsetse’s obligate endosymbiont, Wigglesworthia, was the most abundant bacterium present in the midgut of G. pallidipes, and the density of this bacterium remained largely consistent regardless of whether or not its tsetse host was infected with trypanosomes. These fly populations also housed the commensal symbiont Sodalis, which was found at significantly higher densities in trypanosome infected compared to uninfected flies. Finally, midguts of field-captured G. pallidipes were colonized with distinct, low density communities of environmentally acquired microbes that differed in taxonomic structure depending on parasite infection status and the geographic location from which the flies were collected. Conclusions: The results of this study will enhance our understanding of the tripartite relationship between tsetse, its microbiota and trypanosome vector competence. This information may be useful for developing novel disease control strategies or enhancing the efficacy of those already in use.
Apparent density, trypanosome infection rates and host preference of tsetse flies in the sleeping sickness endemic focus of northwestern Uganda
(BMC Veterinary Research, 2021) Opiro, Robert; Opoke, Robert; Angwech, Harriet; Nakafu, Esther; Oloya, Francis A.; Openy, Geoffrey; Njahira, Moses; Macharia, Mercy; Echodu, Richard; Malinga, Geoffrey M.
African trypanosomiasis, caused by protozoa of the genus Trypanosoma and transmitted by the tsetse fly, is a serious parasitic disease of humans and animals. Reliable data on the vector distribution, feeding preference and the trypanosome species they carry is pertinent to planning sustainable control strategies. Methodology: We deployed 109 biconical traps in 10 villages in two districts of northwestern Uganda to obtain information on the apparent density, trypanosome infection status and blood meal sources of tsetse flies. A subset (272) of the collected samples was analyzed for detection of trypanosomes species and sub-species using a nested PCR protocol based on primers amplifying the Internal Transcribed Spacer (ITS) region of ribosomal DNA. 34 blood-engorged adult tsetse midguts were analyzed for blood meal sources by sequencing of the mitochondrial cytochrome c oxidase 1 (COI) and cytochrome b (cytb) genes. Results: We captured a total of 622 Glossina fuscipes fuscipes tsetse flies (269 males and 353 females) in the two districts with apparent density (AD) ranging from 0.6 to 3.7 flies/trap/day (FTD). 10.7% (29/272) of the flies were infected with one or more trypanosome species. Infection rate was not significantly associated with district of origin (Generalized linear model (GLM), χ2 = 0.018, P = 0.895, df = 1, n = 272) and sex of the fly (χ2 = 1.723, P = 0.189, df = 1, n = 272). However, trypanosome infection was highly significantly associated with the fly’s age based on wing fray category (χ2 = 22.374, P < 0.001, df = 1, n = 272), being higher among the very old than the young tsetse. Nested PCR revealed several species of trypanosomes: T. vivax (6.62%), T. congolense (2.57%), T. brucei and T. simiae each at 0.73%. Blood meal analyses revealed five principal vertebrate hosts, namely, cattle (Bos taurus), humans (Homo sapiens), Nile monitor lizard (Varanus niloticus), African mud turtle (Pelusios chapini) and the African Savanna elephant (Loxodonta africana). Conclusion: We found an infection rate of 10.8% in the tsetse sampled, with all infections attributed to trypanosome species that are causative agents for AAT. However, more verification of this finding using large-scale passive and active screening of human and tsetse samples should be done. Cattle and humans appear to be the most important tsetse hosts in the region and should be considered in the design of control interventions.
Characterization of Ugandan Endemic Aspergillus Species and Identification of Non-Aflatoxigenic Isolates for Potential Biocontrol of Aflatoxins
(Toxins, 2022) Wokorach, Godfrey; Landschoot, Sofie; Lakot, Amerida; Arihona Karyeija, Sidney; Audenaert, Kris; Echodu, Richard; Haesaert, Geert
Acute stunting in children, liver cancer, and death often occur due to human exposure to aflatoxins in food. The severity of aflatoxin contamination depends on the type of Aspergillus fungus infecting the crops. In this study, Aspergillus species were isolated from households’ staple foods and were characterized for different aflatoxin chemotypes. The non-aflatoxigenic chemotypes were evaluated for their ability to reduce aflatoxin levels produced by aflatoxigenic A. flavus strains on maize grains. Aspergillus flavus (63%), A. tamarii (14%), and A. niger (23%) were the main species present. The A. flavus species included isolates that predominantly produced aflatoxins B1 and B2, with most isolates producing a high amount (>20 ug/ L) of aflatoxin B1 (AFB1), and a marginal proportion of them also producing G aflatoxins with a higher level of aflatoxin G1 (AFG1) than AFB1. Some non-aflatoxigenic A. tamarii demonstrated a strong ability to reduce the level of AFB1 by more than 95% when co-inoculated with aflatoxigenic A. flavus. Therefore, field evaluation of both non-aflatoxigenic A. flavus and A. tamarii would be an important step toward developing biocontrol agents for mitigating field contamination of crops with aflatoxins in Uganda.
Distance and Microsphere Aggregation- Based DNA Detection in a Paper-Based Microfluidic Device
(SLAS TECHNOLOGY: Translating Life Sciences Innovation, 2020) Kalish, Brent; Zhang, Jianhou; Edema, Hilary; Luong, James; Roper, Jenna; Beaudette, Chad; Echodu, Richard; Tsutsui, Hideaki
In paper-based microfluidics, the simplest devices are colorimetric, giving qualitative results. However, getting quantitative data can be quite a bit more difficult. Distance-based devices provide a user-friendly means of obtaining quantitative data without the need for any additional equipment, simply by using an included ruler or calibrated markings. This article details the development of a quantitative DNA detection device that utilizes the aggregation of polystyrene microspheres to affect the distance that microspheres wick through filter paper. The microspheres are conjugated to single-stranded DNA (ssDNA) oligomers that are partially complementary to a target strand and, in the presence of the target strand, form a three-strand complex, resulting in the formation of aggregates. The higher the concentration of the target strand, the larger the aggregate, and the shorter the distance wicked by the microspheres. This behavior was investigated across a wide range of target concentrations and under different incubation times to understand aggregate formation. The device was then used to successfully detect a target strand spiked in extracted plant DNA.
Esperanza Window Traps for the collection of anthropophilic blackflies (Diptera: Simuliidae) in Uganda and Tanzania
(PLoS neglected tropical diseases, 2017) Hendy, Adam; Sluydts, Vincent; Tushar, Taylor; De Witte, Jacobus; Odonga, Patrick; Loum, Denis; Nyaraga, Michael; Lakwo, Thomson; Dujardin, Jean-Claude; Post, Rory; Kalinga, Akili; Echodu, Richard
There is an increasing need to evaluate the impact of chemotherapeutic and vector-based interventions as onchocerciasis affected countries work towards eliminating the disease. The Esperanza Window Trap (EWT) provides a possible alternative to human landing collections (HLCs) for the collection of anthropophilic blackflies, yet it is not known whether current designs will prove effective for onchocerciasis vectors throughout sub-Saharan Africa. EWTs were deployed for 41 days in northern Uganda and south eastern Tanzania where different Simulium damnosum sibling species are responsible for disease transmission. The relative efficacy of EWTs and HLCs was compared, and responses of host-seeking blackflies to odour baits, colours, and yeast-produced CO2 were investigated. Blue EWTs baited with CO2 and worn socks collected 42.3% (2,393) of the total S. damnosum s.l. catch in northern Uganda. Numbers were comparable with those collected by HLCs (32.1%, 1,817), and higher than those collected on traps baited with CO2 and BG-Lure (25.6%, 1,446), a synthetic human attractant. Traps performed less well for the collection of S. damnosum s.l. in Tanzania where HLCs (72.5%, 2,432) consistently outperformed both blue (16.8%, 563) and black (10.7%, 360) traps baited with CO2 and worn socks. HLCs (72.3%, 361) also outperformed sock-baited (6.4%, 32) and BG-Lure-baited (21.2%, 106) traps for the collection of anthropophilic Simulium bovis in northern Uganda. Contrasting blackfly distributions were observed on traps in Uganda and Tanzania, indicating differences in behaviour in each area. The success of EWT collections of S. damnosum s.l. in northern Uganda was not replicated in Tanzania, or for the collection of anthropophilic S. bovis. Further research to improve the understanding of behavioural responses of vector sibling species to traps and their attractants should be encouraged.
Evidence of temporal stability in allelic and mitochondrial haplotype diversity in populations of Glossina fuscipes fuscipes (Diptera: Glossinidae) in northern Uganda
(Parasites & Vectors, 2016) Opiro, Robert; Saarman, Norah P.; Echodu, Richard; Opiyo, Elizabeth A.; Dion, Kirstin; Halyard, Alexis; Aksoy, Serap; Caccone, Adalgisa
Glossina fuscipes fuscipes is a tsetse species of high economic importance in Uganda where it is responsible for transmitting animal African trypanosomiasis (AAT) and both the chronic and acute forms of human African trypanosomiasis (HAT). We used genotype data from 17 microsatellites and a mitochondrial DNA marker to assess temporal changes in gene frequency for samples collected between the periods ranging from 2008 to 2014 in nine localities spanning regions known to harbor the two forms of HAT in northern Uganda. Results: Our findings suggest that the majority of the studied populations in both HAT foci are genetically stable across the time span sampled. Pairwise estimates of differentiation using standardized FST and Jost’s DEST between time points sampled for each site were generally low and ranged between 0.0019 and 0.1312 for both sets of indices. We observed the highest values of FST and DEST between time points sampled from Kitgum (KT), Karuma (KR), Moyo (MY) and Pader (PD), and the possible reasons for this are discussed. Effective population size (Ne) estimates using Waple’s temporal method ranged from 103 (95 % CI: 73–138) in Kitgum to 962 (95 % CI: 669–1309) in Oculoi (OC). Additionally, evidence of a bottleneck event was detected in only one population at one time point sampled; Aminakwach (AM-27) from December 2014 (P < 0.03889). Conclusion: Findings suggest general temporal stability of tsetse vectors in foci of both forms of HAT in northern Uganda. Genetic stability and the moderate effective population sizes imply that a re-emergence of vectors from local residual populations missed by control efforts is an important risk. This underscores the need for more sensitive sampling and monitoring to detect residual populations following control activities.
Farmers' practices and their knowledge of biotic constraints to sweetpotato production in East Africa
(Physiological and molecular plant pathology, 2019) Echodu, Richard; Edema, Hilary; Wokorach, Godfrey; Zawedde, Christine; Otim, Geoffrey; Luambano, Nessie; Miinda Ateka, Elijah; Asiimwe, Theodore
Sweetpotato (Ipomoea batatas) is a vital crop for overcoming food insecurity in sub-Saharan Africa and its production is highest in East Africa where yields are high and the growing seasons are short. This cross-country study assessed farmers' local practices and their knowledge of the biotic constraints to sweetpotato production in Uganda, Rwanda, Kenya and Tanzania with the aim of providing empirical data that can ultimately be used to enhance sweetpotato production in these four countries. We collected data from 675 households using a standardized questionnaire integrated with a web-based mobile app. Survey results provided strong evidence that sweetpotato is valued as an important subsistence crop among smallholder farmers on pieces of land of less than 0.4 ha, and we observed that females were more involved than males in sweetpotato production. Sweetpotato was ranked as the second most important staple crop after cassava. Farmers noted an increase in sweetpotato production over the past five years in Uganda and Kenya but a decrease in Rwanda and Tanzania; the proportion of farmers who reported a decrease (33%) and an increase (36%) did not significantly differ. The main constraints to production were reported to be pests (32.6%), drought (21.6%), diseases (11.9%) and lack of diseasefree planting materials (6.8%). Farmers recognized the signs and symptoms associated with sweetpotato diseases on leaves, root tubers, and whole plants, but most were unable to assign the disease type (bacterial, fungal or viral) correctly. We suggest that regional governments improve education, increase the provision of clean planting materials and strengthen breeding programs to improve disease resistance.
Genetic Characterization of Fungal Biodiversity in Storage Grains: Towards Enhancing Food Safety in Northern Uganda
(Microorganisms, 2021) Wokorach, Godfrey; Landschoot, Sofie; Audenaert, Kris; Echodu, Richard; Haesaert, Geert
Worldwide fungal contamination leads to both quantitative and qualitative grain losses during crop growth and/or storage. A greater proportion of grains contamination with toxins often occurs in sub-Saharan Africa, where control measures are limited. We determined fungal diversity and their toxin production ability in household grains meant for human consumption to highlight the risk of mycotoxin exposure among people from northern Uganda. The study underlines the high diversity of fungi that group into 15 genera; many of which are plant pathogens with toxigenic potential. Fusarium verticillioides was the most common fungal species isolated from household grains. The study also indicates that northern Uganda is favored by a high proportion of toxigenic isolates of F. verticillioides, F. andiyazi, and F. proliferatum, which are characterized by a high fumonisins production capability. The fumonisins production ability was not dependent on the species, grain types, and haplotype group to which the isolates belong. The contamination of most household grains with fungi capable of producing a high amount of toxin shows that most people are exposed to an elevated amount of mycotoxins, which shows the frequent problems with mycotoxins that have been reported in most parts of sub-Saharan Africa.
Genetic diversity and population structure of the tsetse fly Glossina fuscipes fuscipes (Diptera: Glossinidae) in Northern Uganda: Implications for vector control
(PLOS Neglected Tropical Diseases, 2017) Opiro, Robert; Saarman, Norah P.; Echodu, Richard; Opiyo, Elizabeth A.; Dion, Kirstin; Halyard, Alexis; Dunn, Augustine W.; Aksoy, Serap; Caccone, Adalgisa
Uganda is the only country where the chronic and acute forms of human African Trypanosomiasis (HAT) or sleeping sickness both occur and are separated by < 100 km in areas north of Lake Kyoga. In Uganda, Glossina fuscipes fuscipes is the main vector of the Trypanosoma parasites responsible for these diseases as well for the animal African Trypanosomiasis (AAT), or Nagana. We used highly polymorphic microsatellite loci and a mitochondrial DNA (mtDNA) marker to provide fine scale spatial resolution of genetic structure of G. f. fuscipes from 42 sampling sites from the northern region of Uganda where a merger of the two disease belts is feared. Based on microsatellite analyses, we found that G. f. fuscipes in northern Uganda are structured into three distinct genetic clusters with varying degrees of interconnectivity among them. Based on genetic assignment and spatial location, we grouped the sampling sites into four genetic units corresponding to northwestern Uganda in the Albert Nile drainage, northeastern Uganda in the Lake Kyoga drainage, western Uganda in the Victoria Nile drainage, and a transition zone between the two northern genetic clusters characterized by high level of genetic admixture. An analysis using HYBRIDLAB supported a hybrid swarm model as most consistent with tsetse genotypes in these admixed samples. Results of mtDNA analyses revealed the presence of 30 haplotypes representing three main haplogroups, whose location broadly overlaps with the microsatellite defined clusters. Migration analyses based on microsatellites point to moderate migration among the northern units located in the Albert Nile, Achwa River, Okole River, and Lake Kyoga drainages, but not between the northern units and the Victoria Nile drainage in the west. Effective population size estimates were variable with low to moderate sizes in most populations and with evidence of recent population bottlenecks, especially in the northeast unit of the Lake Kyoga drainage. Our microsatellite and mtDNA based analyses indicate that G. f. fuscipes movement along the Achwa and Okole rivers may facilitate northwest expansion of the Rhodesiense disease belt in Uganda. We identified tsetse migration corridors and recommend a rolling carpet approach from south of Lake Kyoga northward to minimize disease dispersal and prevent vector re-colonization. Additionally, our findings highlight the need for continuing tsetse monitoring efforts during and after control.
Genetic Diversity and Population Structure of Trypanosoma brucei in Uganda: Implications for the Epidemiology of Sleeping Sickness and Nagana
(PLoS neglected tropical diseases, 2015) Echodu, Richard; Sistrom, Mark; Bateta, Rosemary; Murilla, Grace; Okedi, Loyce; Aksoy, Serap; Enyioha, Chineme; Enyaru, John; Opiyo, Elizabeth; Gibson, Wendy; Caccone, Adalgisa
While Human African Trypanosomiasis (HAT) is in decline on the continent of Africa, the disease still remains a major health problem in Uganda. There are recurrent sporadic outbreaks in the traditionally endemic areas in south-east Uganda, and continued spread to new unaffected areas in central Uganda. We evaluated the evolutionary dynamics underpinning the origin of new foci and the impact of host species on parasite genetic diversity in Uganda. We genotyped 269 Trypanosoma brucei isolates collected from different regions in Uganda and southwestern Kenya at 17 microsatellite loci, and checked for the presence of the SRA gene that confers human infectivity to T. b. rhodesiense. Results Both Bayesian clustering methods and Discriminant Analysis of Principal Components partition Trypanosoma brucei isolates obtained from Uganda and southwestern Kenya into three distinct genetic clusters. Clusters 1 and 3 include isolates from central and southern Uganda, while cluster 2 contains mostly isolates from southwestern Kenya. These three clusters are not sorted by subspecies designation (T. b. brucei vs T. b. rhodesiense), host or date of collection. The analyses also show evidence of genetic admixture among the three genetic clusters and long-range dispersal, suggesting recent and possibly on-going gene flow between them. Conclusions Our results show that the expansion of the disease to the new foci in central Uganda occurred from the northward spread of T. b. rhodesiense (Tbr). They also confirm the emergence of the human infective strains (Tbr) from non-infective T. b. brucei (Tbb) strains of different genetic backgrounds, and the importance of cattle as Tbr reservoir, as confounders that shape the epidemiology of sleeping sickness in the region.
Genetically Distinct Glossina fuscipes fuscipes Populations in the Lake Kyoga Region of Uganda and Its Relevance for Human African Trypanosomiasis
(BioMed research international, 2013) Echodu, Richard; Sistrom, Mark; Hyseni, Chaz; Enyaru, John; Okedi, Loyce; Aksoy, Serap; Caccone, Adalgisa
Tsetse flies (Glossina spp.) are the sole vectors of Trypanosoma brucei—the agent of human (HAT) and animal (AAT) trypanosomiasis. Glossina fuscipes fuscipes (Gff ) is the main vector species in Uganda—the only country where the two forms of HAT disease (rhodesiense and gambiense) occur, with gambiense limited to the northwest. Gff populations cluster in three genetically distinct groups in northern, southern, and western Uganda, respectively, with a contact zone present in central Uganda. Understanding the dynamics of this contact zone is epidemiologically important as the merger of the two diseases is amajor health concern.We used mitochondrial and microsatellite DNA data fromGff samples in the contact zone to understand its spatial extent and temporal stability.We show that this zone is relatively narrow, extending through central Uganda alongmajor rivers with south to north introgression but displaying no sex-biased dispersal. Lack of obvious vicariant barriers suggests that either environmental conditions or reciprocal competitive exclusion could explain the patterns of genetic differentiation observed. Lack of admixture between northern and southern populations may prevent the sympatry of the two forms of HAT disease, although continued control efforts are needed to prevent the recolonization of tsetse-free regions by neighboring populations.
Genome-wide association of trypanosome infection status in the tsetse fly Glossina fuscipes, the major vector of African trypanosomiasis in Uganda
(Research Square, 2022) Saarman, Norah; Son, Jae Hak; Zhao, Hongyu; Cosme, Luciano; Kong, Yong; Li, Mo; Wang, Shiyu; Weiss, Brian; Echodu, Richard; Opiro, Robert; Aksoy, Serap; Caccone, Adalgisa
The primary vector of the trypanosome parasite causing human and animal African trypanosomiasis in Uganda is the riverine tsetse fly Glossina fuscipes fuscipes (Gff). We conducted a genome-wide association (GWA) analysis with field-caught Gff. To increase statistical power, we first improved the Gff genome assembly with whole genome 10X Chromium sequencing, used ddRAD-seq to identify autosomal versus sex-chromosomal regions of the genome with data from 96,965 SNPs, and conducted a GWA with a subset of 50,960 autosomal SNPs from 351 flies. Results assigned a full third of the genome to the sex chromosome, suggested possible sex-chromosome aneuploidy in Gff, and identified a single autosomal SNP to be highly associated with trypanosome infection. The top SNP was ~ 1200 bp upstream of the gene lecithin cholesterol acyltransferase (LCAT), an important component of the molecular pathway that initiates trypanosome lysis and protection in mammals. Results indicate that variation upstream of LCAT and/or linked genetic elements are associated with trypanosome infection susceptibility in Gff. This suggests that there may be naturally occurring genetic variation in Gff that can protect against trypanosome infection, thereby paving the way for targeted research into novel vector control strategies that can promote parasite resistance in natural populations.
Genomic analysis of Sweet potato feathery mottle virus from East Africa
(Physiological and Molecular Plant Pathology, 2020) Wokorach, Godfrey; Otima, Geoffrey; Njuguna, Joyce; Edema, Hilary; Njung'e, Vincent; Machuka, Eunice M.; Yaoc, Nasser; Stomeo, Francesca; Echodu, Richard
Sweet potato feathery mottle virus is a potyvirus that infect sweet potato. The genome of the virus was analysed to understand genetic diversity, evolution and gene flow. Motifs, nucleotide identity and a phylogenetic tree were used to determine phylogroup of the isolates. Gene flow and genetic diversity were tested using DnaSP v.5. Codons evolution were tested using three methods embedded in Datamonkey. The results indicate occurrence of an isolate of phylogroup B within East Africa. Low genetic differentiation was observed between isolates from Kenya and Uganda indicating evidence of gene flow between the two countries. Four genes were found to have positively selected codons bordering or occurring within functional motifs. A motif within P1 gene evolved differently between phylogroup A and B. The evidence of gene flow indicates frequent exchange of the virus between the two countries and P1 gene motif provide a possible marker that can be used for mapping the distribution of the phylogroups.
Heterogeneity in the prevalence and intensity of bovine trypanosomiasis in the districts of Amuru and Nwoya, Northern Uganda
(BMC veterinary research, 2015) Angwech, Harriet; Nyeko, Jack H. P.; Opiyo, Elizabeth A.; Okello-Onen, Joseph; Opiro, Robert; Echodu, Richard; Malinga, Geoffrey M.; Njahira, Moses N.; Skilton, Robert A.
Livestock trypanosomiasis, transmitted mainly by tsetse flies of the genus Glossina is a major constraint to livestock health and productivity in the sub-Saharan Africa. Knowledge of the prevalence and intensity of trypanosomiasis is important in understanding the epidemiology of the disease. The objectives of this study were to (a) assess the prevalence and intensity of trypanosome infections in cattle, and (b) to investigate the reasons for the heterogeneity of the disease in the tsetse infested districts of Amuru and Nwoya, northern Uganda. Methods: A cross-sectional study was conducted from September, 2011 to January, 2012. Blood samples were collected from 816 cattle following jugular vein puncture, and screened for trypanosomes by HCT and ITS-PCR. A Pearson chi-squared test and logistic regression analyses were performed to determine the association between location, age, sex, and prevalence of trypanosome infections. Results: Out of the 816 blood samples examined, 178 (22 %) and 338 (41 %) tested positive for trypanosomiasis by HCT and ITS-PCR, respectively. Trypanosoma vivax infection accounted for 77 % of infections detected by ITS-PCR, T. congolense (16 %), T. brucei s.l (4 %) and mixed (T. vivax/ T. congolense/T.brucei) infections (3 %). The risk of trypanosome infection was significantly associated with cattle age (χ2 = 220.4, df = 3, P < 0.001). The highest proportions of infected animals were adult males (26.7 %) and the least infected were the less than one year old calves (2.0 %). In addition, the risk of trypanosome infection was significantly associated with sex (χ2 = 16.64, df=1, P < 0.001), and males had a significantly higher prevalence of infections (26.8 %) than females (14.6 %). Conclusion: Our results indicate that the prevalence and intensity of trypanosome infections are highly heterogeneous being associated with cattle age, location and sex.
High insecticide resistances levels in Anopheles gambiaes s.l. in northern Uganda and its relevance for future malaria control
(BMC research notes, 2020) Echodu, Richard; Iga, Julius; Oyet, William Samuel; Mireji, Paul; Anena, Juliet; Onanyang, David; Iwiru, Tereza; Lutwama, Julius Julian; Auma Opiyo, Elizabeth
The aim of the study was to determine the level of insecticide resistance and diversity in Anopheles mosquitoes in northern Uganda. Standard WHO insecticide susceptibility test assays were used to test for susceptibility to 0.5% malathion, 0.1% bendiocarb, 0.05% deltamethrin and 0.75% permethrin on 3–5 day old generation one progeny. We also screened for species diversity and knockdown resistance using PCR assay. Results: Anopheles gambiae s.s. is the predominant malaria vector in northern Uganda followed by An. arabiensis. An. gambiae s.s. was susceptible to malathion and bendiocarb with the observed mortality rate of 100% and 98–100% observed respectively while very high resistance was observed with deltamethrin and permethrin. Minimal KDReastern variant homozygous forms of 8.3% in An. gambiae s.s. were detected in Oyam district. In conclusion, this study confirms that An. gambiae s.s. females are susceptible to malathion and bendiocarb while high intensity of resistance was observed with deltamethrin and permethrin in the same area. Use of carbamate and organophosphate insecticides bendiocarb and malathion for indoor residual spraying activities in northern Uganda is highly recommended since high levels of pyrethroids resistance (deltamethrin and permethrin) was detected in the area.
High level of resistance in Anopheles arabiensis mosquito to pyrethroid insecticides from low malaria transmission zone of Moroto district, Karamoja region, Uganda: Implication for malaria vector control
(Research Square, 2020) Echodu, Richard; Anena, Juliet; Iwiru, Tereza; Mireji, Paul; Malinga, Geoffrey Maxwell; Opiyo, Elizabeth A.; Iga, Julius; David, Onanyang
Karamoja region of Uganda previously classified as low malaria transmission zone is currently experiencing significant upsurge of malaria incidences. Long lasting insecticidal nets (LLINs) impregnated with pyrethroids constitute a major tool for malaria control in this region. Efficacy of this tool can be hampered by resistance to the pyrethroids in the Anopheles mosquito vectors. Resistance status of these mosquitoes in this region is poorly understood, effectively hampering better understanding of the impact of LLINs in the malaria control initiative. Here, we assessed susceptibility of the Anopheles arabiensis from the region to deltamethrin, permethrin (pyrethroids) and pirirmiphos-methyl (organophosphate) insecticides. Method: We collected anopheline mosquito larvae from their natural habitats and reared them to adult emergence in situ field insectary in Karamoja region. We then identified them morphological to species level and exposed 513 emerge adult female An gambiae s.l., mosquitoes to diagnostic dosages of deltamethrin (0.05%), permethrin (0.75%) and pirimiphos-methyl (0.25%) pyrethroids exposure using the standard WHO insecticide susceptibility test assay. Synergic assays using piperonyl butoxide (PBO) were done to check for the involvement of detoxification enzymes in pyrethroid resistant populations. We then screened for knockdown resistance (KDR) and mosquito species diversity using Polymerase Chain Reaction (PCR). Results: Majority (96%) of the mosquitoes we sampled were identified as An. arabiensis and 4% as An. gambiae sensu stricto. We observed cross-resistance to both deltamethrin (11.9%) and permethrin (47%) but susceptibility (100% mortality) to pirimiphos-methyl in An. arabiensis. The pre-exposure to PBO ameliorated the resistance to both pyrethroids. We detected homozygous KDR -eastern variant in 1.8 and 50% of the An. arabiensis and An. gambiae s.s. respectively. Conclusion: Anopheles arabiensis and An. gambiae s.s. are the malaria vector in Karamoja region with An. arabiensis predominating. Both species are susceptible to pirimiphos-methyl but resistant to both deltamethrin and permethrin, through a metabolic process (phenotype). Mosquotoes with genetic (kdr) mutations for resistance were minimal and hence have minimal contribution to the pyrethroid resistance profile. An. arabiensis can thus be controled in Karamoja region using deltamethrin and/or permethrin impregnated mosquito nets integrated with PBO and/or through indoor residual spraying of sprayable human dwellings with pirimiphos-methyl.
High prevalence of Pfmdr‑1 N86 and D1246 genotypes detected among febrile malaria outpatients attending Lira Regional Referral Hospital, Northern Uganda
(BMC Research Notes, 2019) Achol, Emmanuel; Ochaya, Stephen; Malinga, Geoffrey M.; Edema, Hillary; Echodu, Richard
To determine the prevalence of Plasmodium falciparum multi-drug resistant gene-1 (Pfmdr-1) N86Y and D1246Y genotypes among febrile malaria outpatients attending Lira Regional Referral Hospital, Uganda. Results: Overall, 92.3% (n = 48/52) and 90% (n = 45/50) of the parasites detected carried the wild type alleles 1246D and N86, respectively. Only 7.7% (n = 4/52) and 10% (n = 5/50) of these P. falciparum isolates carried the Pfmdr-1 mutant alleles 1246Y and 86Y, respectively. Our results show high prevalence of wild type alleles N86 and D1246 in P. falciparum isolates from Lira Regional Referral Hospital, which could translate to a decreased sensitivity to artemetherlumefantrine. Continued monitoring of prevalence of single nucleotide polymorphisms is warranted to timely inform malaria treatment policies and guidelines.
Household Predictors of Incidence of Malaria in Northern Uganda: Its Implication for Future Malaria Control
(Research Square, 2020) Echodu, Richard; Oyet, William Sam; Iwiru, Tereza; Apili, Felister; Lutwama, Julius Julian; Auma Opiyo, Elizabeth; Otim, Ochan
Use of indoor residual spraying (IRS), long-lasting insecticidal nets (LLINS) and treatment with artemisinin-based combination therapy (ACT) have been greatly promoted in northern Uganda but the region still records highest number of malaria cases with prevalence up to 63%. This study assesses household predicators of malaria in the region and its impact on incidence of malaria at household levels. Methods: A cross-sectional study was conducted in four districts of Gulu, Oyam, Kitgum and Agago covering sixteen known hyper-endemics villages with high malaria burden in northern Uganda. In total, 193 households were surveyed. Data was collected through pre-tested structured questionnaires and systematically coded and analyzed using R software. Results: Women headed 58% of the 193 households surveyed. Six hundred and five (605) individuals were declared to have spent a night in the 193 households surveyed. Nighttime is when mosquitoes mostly gain access to victims in the study area. On average, there were two bed nets per household and out of the 605 individuals declared, 502 502 (86%) spent the night prior to interview under a bed net. Despite this effort, these households still reported malaria incidences in the last three months. Overall, children were prone to malaria more than adults by a ratio of 3:2, and in general, malaria incidences were strongly related to lack of bed nets or use thereof, and also linked directly to the number of individuals in a house. Households without bed nets controlled malaria by means of IRS in combination with closing doors (with the hope of keeping mosquitos at bay), draining stagnant water pool where mosquitos lay their eggs, trimming mosquito covers (grass) around homestead and/or receiving treatment after malaria incidences. When given a choice between insecticides (IRS) and treated bed nets, 1 in 3 households preferred treated bed nets. At the same time, bed nets were perceived unnecessary once IRS was applied. If true, the driving force to spraying insecticides indoor then becomes lack of a bed net. Conclusions: Household predicators of incidence of malaria in northern Uganda includes bed nets, use of treated bed nets, and indoor residual spraying with households not practicing any of these bearing the heaviest burden of malaria. Hierarchical clustering on principal components (HCPC) clusters households into four types in northern Uganda, 1) household that use bed nets and sleep in houses sprayed with insecticides; 2) households that use bed nets but no indoor residual spraying with insecticides; 3) households that have no bed nets and no indoor residual spraying; and 4) test bed nets before use. An opportunity therefore arises for tailoring malaria messages to fit each cluster of households given that clustering here appears not to be random. Malaria incidence was higher in children as compared to the adults that necessities having guidelines for management of interventions in local community setting.
Household Predictors of Malaria Episode in Northern Uganda: Its Implication for Future Malaria Control
(Research Square, 2021) Echodu, Richard; Oyet, William Sam; Iwiru, Tereza; Apili, Felister; Lutwama, Julius Julian; Auma Opiyo, Elizabeth; Otim, Ochan
Uses of indoor residual spraying (IRS), long-lasting insecticidal nets (LLINS) and treatment with artemisinin-based combination therapy (ACT) are greatly promoted in northern part of Uganda as mitigating strategies for malaria episodes. Unfortunately, the region still records the highest malaria prevalence of 63%. This study assesses household predicators of malaria in the region and their impact on malaria episodes at the household levels. Methods: A cross-sectional study was conducted in four districts of Gulu, Oyam, Kitgum and Agago covering sixteen villages in northern Uganda. In total, 193 households were surveyed. Data was collected through pre-tested structured questionnaire and systematically coded for analysis using R software. Results: Women headed 58% of the 193 households surveyed. Six hundred and five (605) individuals were declared to have spent the previous night in these households. On average, there were two bed nets per household and 502 (86%) spent the night prior to interview under a bed net. Overall, malaria episodes were strongly related to lack of bed nets or lack of use thereof, and directly linked to the number of individuals in a household. Children were prone to malaria more than adults by a ratio of 2:1. When given a choice between insecticides (IRS) and treated bed nets, 1 in 3 households preferred treated bed nets. At the same time, data suggests that bed nets were perceived unnecessary once IRS was applied. If true, the driving force to spraying insecticides indoor then becomes lack of a bed net. Conclusions: Household predicators of incidence of malaria in northern Uganda includes bed nets, use of treated bed nets, and indoor residual spraying with households not practicing any of these bearing the heaviest burden of malaria. Hierarchical clustering on principal components (HCPC) clusters households into four types in northern Uganda, 1) household that use bed nets and sleep in houses sprayed with insecticides; 2) households that use bed nets but no indoor residual spraying with insecticides; 3) households that have no bed nets and no indoor residual spraying; and 4) test bed nets before use. Malaria incidence was higher in children as compared to the adults.

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