Browsing by Author "Mchau, Geofrey"

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Evaluation of a point-of-use device used for autoantibody analysis and its potential for following microcystin leucine-arginine exposure
(Frontiers, 2024-02-09) Ma, Hui; Loscher, Christine; Parle-McDermott, Anne; Fitzgerald, Jenny; Meneely, Julie; Elliott, Christopher; Welten, Richard; Mchau, Geofrey; Makule, Edna; Machunda, Revocatus; Gong, Yun; Kimanya, Martin; Crawley, Aoife; Maguire, Ivan; Murphy, Caroline; Kennedy, Richard
Introduction: Globally, the need for measuring exposure to algal toxins has become urgent due to ever-increasing reports of contamination in sea and freshwater, in shellfish and fish stocks and in aerosols. Methods: To address this issue, we evaluated the potential of determining autoantibodies to a panel of biomarkers known to be elevated following exposure to the hepatotoxin microcystin leucine-arginine. The presence of autoantibodies, specific to four selected stress-response, metabolomic and chaperone biomarkers, namely, Heat shock protein 1, Triosephosphate isomerase, Peroxiredoxin 1 and Peroxiredoxin 2 was employed in screening 371 serum samples from microcystin-exposed individuals in Tanzania. In addition, the capacity of the LightDeck fluorescence-based detector, a point-of-use device, to monitor these autoantibody responses in comparison to enzyme-linked immunosorbent assay was evaluated. Results: By using the determination of autoantibodies to this novel panel of biomarkers an altered response was observed following microcystin exposure, with levels generally upregulated. The presence of elevated levels of microcystin leucine-arginine in water, as well as in food sources in Tanzania, may potentially have significant health effects on the population. Discussion: This novel biomarker panel may have potential for the detection of microcystin leucine-arginine exposure as well as various microcystin exposure-associated cancers (e.g., hepatocellular cancer and colorectal cancer). In addition, the utilisation of the LightDeck point-of-use device proved successful for the rapid analysis of this biomarker panel.
First Report of the Co‑occurrence of Cylindrospermopsin, Nodularin and Microcystins in the Freshwaters of Lake Victoria, Tanzania
(Scientific Research Publishing, 2020-07-26) Mchau, Geofrey; Machunda, Machunda; Kimanya, Kimanya; Gong 2, Yun; Mpolya, Emmanuel; Meneely, Julie; Elliott, Christopher; Greer, Brett
Abstract There is a global concern regarding the increase of cyanotoxins in freshwater and their potential effects on human health. The existence of multiple toxins in freshwater can result in an increased risk of their bioaccumulation in humans from their inges- tion through contaminated drinking water or recreational activities. This study, the first of its kind, was conducted to deter- mine the occurrence of thirteen cyanotoxins namely; microcystins (-LA, -LF, -LR, -LY, -LW, -RR, -YR, -WR, dm MC-RR and dm MC-LR), anatoxin-a, nodularin and cylindrospermopsin in the freshwaters of Lake Victoria in Tanzania. A total of 23 sites were selected for water sampling. Samples were randomly collected from lakeshores (n = 54), wells (n = 66) and piped water (n = 18) in two phases, February (dry season) and December (rainy season) 2018. Samples (n = 138) were analysed using liquid chromatography mass spectrometry (UPLC-MS/MS). Cylindrospermopsin was the most abundant cyanotoxin detected in the lakeshores, with eight of the nine collection sites (89%) reporting cylindrospermopsin in phase I, compared to three out of nine (33%) in phase II. Microcystin congeners -RR, -LR and -YR were detected in phase I, with microcystins -RR and -LR detected in phase II. MC concentrations ranged from 0.003 to 0.007 μg/L for MC-RR, 0.01–0.013 μg/L for MC-LR and 0.004 to 0.01 μg/L for cylindrospermopsin, with nodularin reported once at a concentration of 0.01 μg/L. No cyanotoxins were detected in wells or in treated pipe water samples. The existence of multiple toxins in different collection sites may lead to synergistic effects and increase the toxicological risk to humans. This is the first study to report the pres- ence of cylindrospermopsin and nodularin in the freshwaters of Lake Victoria
Harmful algal bloom and associated health risks among users of Lake Victoria freshwater: Ukerewe Island, Tanzania
(J Water Health, 2019-07-24) Mchau, Geofrey; Makule, Edna; Machunda, Revocatus; Gong, Yun; Kimanya, Martin
There is a global concern regarding the occurrences of harmful algal blooms (HABs) and their effects on human health. Lake Victoria (LV) has been reported to face eutrophication challenges, resulting in an increase of bloom-forming cyanobacteria. This study is aimed at understanding the association of HABs and health risks at Ukerewe Island. A cross-sectional study conducted on 432 study subjects and water samples for cyanobacteria species identification were collected at LV shores. The results reveal that concentrations of cyanobacteria cells are beyond (WHO) acceptable limits; species of Microcystis aeruginosa range from 90,361.63 to 3,032.031.65 cells/mL and Anabaena spp. range from 13,310.00 to 4,814,702 cells/mL. Water usage indicates that 31% use lake water, 53% well water and 16% treated supplied pipe water. Vomiting and throat irritation was highly reported by lake water users as compared to wells and pipe water (P < 0.001). Gastrointestinal illness (GI) was significantly elevated among lake water users as compared to pipe and well water users (P < 0.001). Visible blooms in lake water were associated with GI, skin irritation and vomiting as compared to water without visible blooms (P < 0.001). The concentration of cyanobacteria blooms poses greater risks when water is used without treatment.
Integrating contact tracing and whole- genome sequencing to track the elimination of dog-mediated rabies: An observational and genomic study
(eLife Sciences Publications Ltd, 2023-05-25) Lushasi, Kennedy; Brunker, Kirstyn; Rajeev, Malavika; Ferguson, Elaine; Jaswant, Gurdeep; Baker, Laurie; Biek, Roman; Changalucha, Joel; Cleaveland, Sarah; Czupryna, Anna; Fooks, Anthony; Govella, Nicodemus; Haydon, Daniel; Johnson, Paul; Kazwala, Rudovick; Lembo, Tiziana; Masoud, Msanif; Maziku, Matthew; Mbunda, Eberhard; Mchau, Geofrey; Mohamed, Ally; Mpolya, Emmanuel; Ngeleja, Chanasa; Ng'habi, Kija; Nonga, Hezron; Omar, Kassim; Rysava, Kristyna; Sambo, Maganga; Sikana, Lwitiko; Steenson, Rachel; Hampson, Katie
Background: Dog-mediated rabies is endemic across Africa causing thousands of human deaths annually. A One Health approach to rabies is advocated, comprising emergency post-exposure vaccination of bite victims and mass dog vaccination to break the transmission cycle. However, the impacts and cost-effectiveness of these components are difficult to disentangle. Methods: We combined contact tracing with whole-genome sequencing to track rabies transmission in the animal reservoir and spillover risk to humans from 2010 to 2020, investigating how the components of a One Health approach reduced the disease burden and eliminated rabies from Pemba Island, Tanzania. With the resulting high-resolution spatiotemporal and genomic data, we inferred transmission chains and estimated case detection. Using a decision tree model, we quantified the public health burden and evaluated the impact and cost-effectiveness of interventions over a 10-year time horizon. Results: We resolved five transmission chains co-circulating on Pemba from 2010 that were all eliminated by May 2014. During this period, rabid dogs, human rabies exposures and deaths all progressively declined following initiation and improved implementation of annual islandwide dog vaccination. We identified two introductions to Pemba in late 2016 that seeded re-emergence after dog vaccination had lapsed. The ensuing outbreak was eliminated in October 2018 through reinstated islandwide dog vaccination. While post-exposure vaccines were projected to be highly cost-effective ($256 per death averted), only dog vaccination interrupts transmission. A combined One Health approach of routine annual dog vaccination together with free post-exposure vaccines for bite victims, rapidly eliminates rabies, is highly cost-effective ($1657 per death averted) and by maintaining rabies freedom prevents over 30 families from suffering traumatic rabid dog bites annually on Pemba island. Conclusions: A One Health approach underpinned by dog vaccination is an efficient, cost-effective, equitable, and feasible approach to rabies elimination, but needs scaling up across connected populations to sustain the benefits of elimination, as seen on Pemba, and for similar progress to be achieved elsewhere.
Integrating contact tracing and wholegenome sequencing to track the elimination of dog-mediated rabies: An observational and genomic study
(eLife, 2023-05-23) Lushasi, Kennedy; Brunker, Kirstyn; Rajeev, Malavika; Ferguson, Elaine; Jaswant, Gurdeep; Baker, Laurie; Biek, Roman; Changalucha, Joel; Cleaveland, Sarah; Czupryna, Anna; Fooks, Anthony; Govella, Nicodemus; Haydon, Daniel; Johnson, Paul; Kazwala, Rudovick; Lembo, Tiziana; Marston, Denise; Masoud, Msanif; Maziku, Matthew; Mbunda, Eberhard; Mchau, Geofrey; Mohamed, Ally; Mpolya, Emmanuel; Ngeleja, Chanasa; Ng'habi, Kija; Nonga, Hezron; Omar, Kassim; Rysava, Kristyna; Sambo, Maganga; Sikana, Lwitiko; Steenson, Rachel; Hampson, Katie
Background: Dog-mediated rabies is endemic across Africa causing thousands of human deaths annually. A One Health approach to rabies is advocated, comprising emergency post-exposure vaccination of bite victims and mass dog vaccination to break the transmission cycle. However, the impacts and cost-effectiveness of these components are difficult to disentangle. Methods: We combined contact tracing with whole-genome sequencing to track rabies transmission in the animal reservoir and spillover risk to humans from 2010 to 2020, investigating how the components of a One Health approach reduced the disease burden and eliminated rabies from Pemba Island, Tanzania. With the resulting high-resolution spatiotemporal and genomic data, we inferred transmission chains and estimated case detection. Using a decision tree model, we quantified the public health burden and evaluated the impact and cost-effectiveness of interventions over a 10-year time horizon. Results: We resolved five transmission chains co-circulating on Pemba from 2010 that were all eliminated by May 2014. During this period, rabid dogs, human rabies exposures and deaths all progressively declined following initiation and improved implementation of annual islandwide dog vaccination. We identified two introductions to Pemba in late 2016 that seeded re-emergence after dog vaccination had lapsed. The ensuing outbreak was eliminated in October 2018 through reinstated islandwide dog vaccination. While post-exposure vaccines were projected to be highly cost-effective ($256 per death averted), only dog vaccination interrupts transmission. A combined One Health approach of routine annual dog vaccination together with free post-exposure vaccines for bite victims, rapidly eliminates rabies, is highly cost-effective ($1657 per death averted) and by maintaining rabies freedom prevents over 30 families from suffering traumatic rabid dog bites annually on Pemba island. Conclusions: A One Health approach underpinned by dog vaccination is an efficient, cost-effective, equitable, and feasible approach to rabies elimination, but needs scaling up across connected populations to sustain the benefits of elimination, as seen on Pemba, and for similar progress to be achieved elsewhere.
Phycocyanin as a proxy for algal blooms in surface waters: case study of Ukerewe Island, Tanzania
(IWA Publishing, 2019-01-08) Mchau, Geofrey; Makule, Edna; Machunda, Revocatus; Gong, Yun; Kimanya, Martin
Knowledge of the parameters that contribute to water body eutrophication is essential for proper monitoring and management of water quality for human consumption. This study assessed water quality parameters in relation to phycocyanin (PC) as a proxy indicator for harmful algal blooms (HABs). Samples were collected from 23 water sources – lakes, wells, springs and boreholes – in selected villages, for six months. Parameters measured included temperature, pH, redox potential, dissolved oxygen, electrical conductivity, total dissolved solids, nitrate nitrogen, nitrite nitrogen, phosphorus, reactive phosphate and total chlorophyll, which were related to (PC) occurrence. The PC concentration detected in Lake Victoria ranged from 5 to 58.4 μg/l above the WHO alert level and exceeded that in other water sources by almost 30 μg/l (P < 0.001). Univariate relationship between water quality parameters and PC indicates association with temperature, redox potential, total chlorophyll, nitrate nitrogen, nitrite nitrogen, phosphate and reactive phosphorus (P < 0.001). The multivariate model indicates that redox potential, nitrate nitrogen and phosphorus are significant statistically (P < 0.05). A predictive model indicates that nitrate nitrogen and reactive phosphorus contribute significantly to PC occurrence whereby unit (1 mg/l) increases in these parameters increase PC by 9.55 and 4.38 μg/l (P < 0.05) respectively. This study demonstrates that water quality parameters can be used to predict increases in PC and hence as a proxy for HABs. It remains important to be able to classify algal blooms, to understand which species are present and their potential cyanotoxin production.
Reservoir dynamics of rabies in south-east Tanzania and the roles of cross-species transmission and domestic dog vaccination
(John Wiley & Sons, Inc., 2021-08-21) Lushasi, Kennedy; Hayes, Sarah; Ferguson, Elaine; Changalucha, Joel; Cleaveland, Sarah; Govella, Nicodem; Haydon, Daniel; Sambo, Maganga; Mchau, Geofrey; Mpolya, Emmanuel; Mtema, Zacharia; Nonga, Hezron; Steenson, Rachel; Nouvellet, Pierre; Donnelly, Christl; Hampson, Katie
Understanding the role of different species in the transmission of multi-host pathogens, such as rabies virus, is vital for effective control strategies. Across most of sub-Saharan Africa domestic dogs Canis familiaris are considered the reservoir for rabies, but the role of wildlife has been long debated. Here we explore the multi-host transmission dynamics of rabies across south-east Tanzania. Between January 2011 and July 2019, data on probable rabies cases were collected in the regions of Lindi and Mtwara. Hospital records of animal-bite patients presenting to healthcare facilities were used as sentinels for animal contact tracing. The timing, location and species of probable rabid animals were used to reconstruct transmission trees to infer who infected whom and the relative frequencies of within- and between-species transmission. During the study, 688 probable human rabies exposures were identified, resulting in 47 deaths. Of these exposures, 389 were from domestic dogs (56.5%) and 262 from jackals (38.1%). Over the same period, 549 probable animal rabies cases were traced: 303 in domestic dogs (55.2%) and 221 in jackals (40.3%), with the remainder in domestic cats and other wildlife species. Although dog-to-dog transmission was most commonly inferred (40.5% of transmission events), a third of inferred events involved wildlife-to-wildlife transmission (32.6%), and evidence suggested some sustained transmission chains within jackal populations. A steady decline in probable rabies cases in both humans and animals coincided with the implementation of widespread domestic dog vaccination during the first 6 years of the study. Following the lapse of this program, dog rabies cases began to increase in one of the northernmost districts. Synthesis and applications. In south-east Tanzania, despite a relatively high incidence of rabies in wildlife and evidence of wildlife-to-wildlife transmission, domestic dogs remain essential to the reservoir of infection. Continued dog vaccination alongside improved surveillance would allow a fuller understanding of the role of wildlife in maintaining transmission in this area. Nonetheless, dog vaccination clearly suppressed rabies in both domestic dog and wildlife populations, reducing both public health and conservation risks and, if sustained, has potential to eliminate rabies from this region.