Browsing by Author "Echodu, Richard"

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    Apparent density, trypanosome infection rates and host preference of tsetse flies in the sleeping sickness endemic focus of Northwestern Uganda.
    (Springer Nature, 2021-11-29) Opiro, Robert; Opoke, Robert; Angwech, Harriet; Nakafu, Esther; Oloya, Francis A; Openy, Geoffrey; Njahira, Moses; Macharia, Mercy; Echodu, Richard; Malinga, Geoffrey M.; Opiyo, Elizabeth A.
    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. 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. 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). 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.
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    Polymorphism of pfmdr1 gene mutation conferring resistance to artemisinin‐based combination therapy in plasmodium falciparum in patients at Gulu regional referral hospital in northern Uganda
    (John Wiley & Son, 2026-06-09) Amito, Florence Peace; Angwech, Harriet; Ojok, Lonzy; Wokorach, Godfrey; Ochaya, Stephen; Ogwang, Quinto; Opiro, Robert; Echodu, Richard
    Background Malaria is one of the most devastating infectious diseases in humans, and antimalarial drugs have been used to combat it with minimal success. Worldwide, malaria treatment is threatened by the emergence and spread of artemisinin resistance, which is associated with mutations in the PfK13 propeller domain. In Sub-saharan Africa, data relating to the prevalence of Plasmodium falciparum malaria infection in association with the Kelch 13 mutations are mainly from research settings outside disease-endemic areas. This study is aimed at establishing the prevalence of P. falciparum malaria infection in association with Kelch 13 mutations among patients presenting with fever at Gulu Regional Referral Hospital (GRRH) in northern Uganda. Methods This cross-sectional study enrolled all participants presenting with fever at GRRH between April 2022 and January 2024. Data on adults and children aged ≥ 6 months with fever and confirmed diagnosis of malaria using mRDT, microscopy, and PCR were collected. Parasite DNA was extracted using the Chelex method and sequenced for multidrug resistance genes, and Sanger customized CRF forms were used to capture variables on social demographics, clinical presentation, and treatment. Data were analyzed using IBM SPSS Version 25, and the sequenced data were analyzed using molecular evolutionary genetic analysis (MEGA) Version 11.1.10. All sequences from a single population were aligned using the National Center for Biotechnology Information (NCBI) database. Results In total, 353 participants were recruited, and the overall prevalence of P. falciparum malaria was 60.6% (n = 214), with the highest number of cases registered in Gulu City (24.9%). Women were the most affected participants (37.1%). The most common clinical presentations among the participants were fever (91.8%; n = 324), chills (90.7%; n = 320), and headaches (72.0%; n = 254). Genotyping results of the mutant genes showed that of all 214 P. falciparum isolates examined, the pfmdr1 SNP at Codon 1034 1042 (29.6%, n = 94) had the highest prevalence, followed by the pfmdr SNP at Codon 86 184 (28%, n = 89), and the SNP fragment at codon 1246 (25.8%, n = 82) recorded the lowest prevalence. Kelch 13 propeller gene, known to be associated with artemisinin resistance, was also isolated in 16.7% (n = 53) of the samples. There was a 90.1% (n = 318) prevalence of the SNPs 86 184, 1034 1042 of the pfmdr1 gene, and K13 propeller gene, with no significant difference between the sexes (p = 0.756). The SNP at Codon 1246 of pfmdr1 showed a significant difference between the location and mutation (p = 0.017). The median parasite load in patients with mutations in 86 184, 1034 1042, and K13 propeller genes varied significantly among patients who received treatment p ≤ 0.0001, p = 0.0061, and p = 0.012, respectively. Conclusion The presence of pfmdr1 mutant genes suggests resistance of P. falciparum to most antimalarial drugs used in treatment. Therefore, it is important to monitor the prevalence of Kelch 13 mutations and P. falciparum to contribute to global efforts to control and eliminate malaria.
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    Spatial distribution of tsetse flies and trypanosome infection status in a vector genetic transition zone in northern Uganda
    (Journal of Parasitology Research, 2022-06-01) Opiro, Robert; Okello, Allele Moses; Opoke, Robert; Oloya, Francis A.; Nakafu, Esther; Iwiru, Teresa; Echodu, Richard; Malinga, Geoffrey M.; Bargul, Joel L.; Opiyo, Elizabeth A.
    Background. Tsetse flies are vectors of the genus Trypanosoma that cause African trypanosomiasis, a serious parasitic disease of people and animals. Reliable data on the vector distribution and the trypanosome species they carry is pertinent for planning sustainable control strategies. This study was carried out to estimate the spatial distribution, apparent density, and trypanosome infection rates of tsetse flies in two districts that fall within a vector genetic transition zone in northern Uganda. Materials and Methods. Capturing of tsetse flies was done using biconical traps deployed in eight villages in Oyam and Otuke, two districts that fall within the vector genetic transition zone in northern Uganda. Trapped tsetse flies were sexed and morphologically identified to species level and subsequently analyzed for detection of trypanosome DNA. Trypanosome DNA was detected using a nested PCR protocol based on primers amplifying the internal transcribed spacer (ITS) region of ribosomal DNA. Results. A total of 717 flies (406 females; 311 males) were caught, all belonging to the Glossina fuscipes fuscipes species. The overall average flies/trap/day (FTD) was (). Out of the 477 (201 male; 276 females) flies analyzed, 7.13% (34/477) were positive for one or more trypanosome species. Three species of bovine trypanosomes were detected, namely, Trypanosoma vivax, 61.76% (21/34), T. congolense, 26.47% (9/34), and T. brucei brucei, 5.88% (2/34), and two cases of mixed infection of T. congolense and T. brucei brucei, 5.88% (2/34). The infection rate was not significantly associated with the sex of the fly (generalized linear model (GLM), , , ) and district of origin (, , , ). However, trypanosome infection was highly significantly associated with the fly’s age based on wing fray category (, , , ), being higher among the very old than the young. Conclusion. The relatively high tsetse density and trypanosome infection rate indicate that the transition zone is a high-risk area for perpetuating animal trypanosomiasis. Therefore, appropriate mitigation measures should be instituted targeting tsetse and other biting flies that may play a role as disease vectors, given the predominance of T. vivax in the tsetse samples.