Economic burden of livestock disease and drought in Northern Tanzania

Livestock-dependent communities face considerable livestock disease and drought risk, which can impact herd value, income and consumption. This paper summarizes economic data collected from 404 households in Arusha and Manyara regions of Northern Tanzania in 2016. They provide estimates for (i) herd loss due to disease and drought as a fraction of herd value and income, (ii) the relative risk of disease and drought in small versus large ruminants and (iii) the relationship between livestock disease outcomes and household expenditures. We find that disease and drought losses comprise 10 to 4% of sheep, cattle and goat herd value, and amount to an estimated 62.1% of household income. The drought and disease risk ratios for small versus large ruminants indicate that small stock face higher disease risk, while large ruminants are affected more by drought. Furthermore, cattle abortions are negatively related to schooling expenditure and positively associated with increases in off-farm food expenditure related to livestock management, presumably through increased investments in prevention and therapy. These results suggest that climatic variability and livestock diseases are an important source of economic vulnerability and reducing this burden may help alleviate poverty in livestock-dependent communities

Assessment of animal hosts of pathogenic Leptospira in northern Tanzania

Funding: This work was supported by the Wellcome Trust (grant number 096400/Z/11/Z; https://wellcome.ac.uk/). JEBH, VPM, JAC, and SC received support from the Research Councils UK, UK Department for International Development, and UK Biotechnology and Biological Sciences Research Council (BBSRC) (grant numbers BB/J010367/1, BB/L018926, BB/L017679, BB/L018845; http://www.bbsrc.ac.uk/). JAC and VPM also received support from the US National Institutes of Health (NIH)-National Science Foundation (NSF) Ecology and Evolution of Infectious Disease program (R01TW009237; https://www.fic.nih.gov/programs/pages/ecology-infectious-diseases.aspx). MM received support from the BBSRC East of Scotland Bioscience Doctoral Training Partnership (http://www.eastscotbiodtp.ac.uk/). MJM received support from a University of Otago Frances G. Cotter Scholarship and a University of Otago MacGibbon PhD Travel Fellowship (http://www.otago.ac.nz/). VPM and JAC received support from the US National Institutes of Health National Institute for Allergy and Infectious (grant number R01 AI121378; https://www.niaid.nih.gov/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Data Availability: Datasets supporting this manuscript are available through: http://dx.doi.org/10.5525/gla.researchdata.582. Unique sequences generated through this study are available through GenBank (accession numbers MF955862 to MF955882).Peer reviewedPublisher PD

Economic burden of livestock disease and drought in Northern Tanzania

Livestock-dependent communities face considerable livestock disease and drought risk, which can impact herd value, income and consumption. This paper summarizes economic data collected from 404 households in Arusha and Manyara regions of Northern Tanzania in 2016. They provide estimates for (i) herd loss due to disease and drought as a fraction of herd value and income, (ii) the relative risk of disease and drought in small versus large ruminants and (iii) the relationship between livestock disease outcomes and household expenditures. We find that disease and drought losses comprise 10 to 4% of sheep, cattle and goat herd value, and amount to an estimated 62.1% of household income. The drought and disease risk ratios for small versus large ruminants indicate that small stock face higher disease risk, while large ruminants are affected more by drought. Furthermore, cattle abortions are negatively related to schooling expenditure and positively associated with increases in off-farm food expenditure related to livestock management, presumably through increased investments in prevention and therapy. These results suggest that climatic variability and livestock diseases are an important source of economic vulnerability and reducing this burden may help alleviate poverty in livestock-dependent communities

Estimating acute human leptospirosis incidence in northern Tanzania using sentinel site and community behavioural surveillance

Many infectious diseases lack robust estimates of incidence from endemic areas, and extrapolating incidence when there are few locations with data remains a major challenge in burden of disease estimation. We sought to combine sentinel surveillance with community behavioural surveillance to estimate leptospirosis incidence. We administered a questionnaire gathering responses on established locally relevant leptospirosis risk factors and recent fever to livestock‐owning community members across six districts in northern Tanzania and applied a logistic regression model predicting leptospirosis risk on the basis of behavioural factors that had been previously developed among patients with fever in Moshi Municipal and Moshi Rural Districts. We aggregated probability of leptospirosis by district and estimated incidence in each district by standardizing probabilities to those previously estimated for Moshi Districts. We recruited 286 community participants: Hai District (n = 11), Longido District (59), Monduli District (56), Moshi Municipal District (103), Moshi Rural District (44) and Rombo District (13). The mean predicted probability of leptospirosis by district was Hai 0.029 (0.005, 0.095), Longido 0.071 (0.009, 0.235), Monduli 0.055 (0.009, 0.206), Moshi Rural 0.014 (0.002, 0.049), Moshi Municipal 0.015 (0.004, 0.048) and Rombo 0.031 (0.006, 0.121). We estimated the annual incidence (upper and lower bounds of estimate) per 100,000 people of human leptospirosis among livestock owners by district as Hai 35 (6, 114), Longido 85 (11, 282), Monduli 66 (11, 247), Moshi Rural 17 (2, 59), Moshi Municipal 18 (5, 58) and Rombo 47 (7, 145). Use of community behavioural surveillance may be a useful tool for extrapolating disease incidence beyond sentinel surveillance sites

Latent class evaluation of the performance of serological tests for exposure to Brucella spp. in cattle, sheep, and goats in Tanzania

Background: Brucellosis is a neglected zoonosis endemic in many countries, including regions of sub-Saharan Africa. Evaluated diagnostic tools for the detection of exposure to Brucella spp. are important for disease surveillance and guiding prevention and control activities. Methods and findings: Bayesian latent class analysis was used to evaluate performance of the Rose Bengal plate test (RBT) and a competitive ELISA (cELISA) in detecting Brucella spp. exposure at the individual animal-level for cattle, sheep, and goats in Tanzania. Median posterior estimates of RBT sensitivity were: 0.779 (95% Bayesian credibility interval (BCI): 0.570–0.894), 0.893 (0.636–0.989), and 0.807 (0.575–0.966), and for cELISA were: 0.623 (0.443–0.790), 0.409 (0.241–0.644), and 0.561 (0.376–0.713), for cattle, sheep, and goats, respectively. Sensitivity BCIs were wide, with the widest for cELISA in sheep. RBT and cELISA median posterior estimates of specificity were high across species models: RBT ranged between 0.989 (0.980–0.998) and 0.995 (0.985–0.999), and cELISA between 0.984 (0.974–0.995) and 0.996 (0.988–1). Each species model generated seroprevalence estimates for two livestock subpopulations, pastoralist and non-pastoralist. Pastoralist seroprevalence estimates were: 0.063 (0.045–0.090), 0.033 (0.018–0.049), and 0.051 (0.034–0.076), for cattle, sheep, and goats, respectively. Non-pastoralist seroprevalence estimates were below 0.01 for all species models. Series and parallel diagnostic approaches were evaluated. Parallel outperformed a series approach. Median posterior estimates for parallel testing were ≥0.920 (0.760–0.986) for sensitivity and ≥0.973 (0.955–0.992) for specificity, for all species models. Conclusions: Our findings indicate that Brucella spp. surveillance in Tanzania using RBT and cELISA in parallel at the animal-level would give high test performance. There is a need to evaluate strategies for implementing parallel testing at the herd- and flock-level. Our findings can assist in generating robust Brucella spp. exposure estimates for livestock in Tanzania and wider sub-Saharan Africa. The adoption of locally evaluated robust diagnostic tests in setting-specific surveillance is an important step towards brucellosis prevention and control

Cystic echinococcosis in northern Tanzania: a pilot study in Maasai livestock-keeping communities

Background: There are close similarities between the life-cycles of Echinococcus granulosus sensu lato (E. granulosus s.l.) that causes cystic echinococcosis (CE) in humans and Taenia multiceps/Coenurus cerebralis that causes cerebral coenurosis in small ruminants. Recent evidence highlights that livestock in Maasai communities of northern Tanzania are suffering from increases in the prevalence of cerebral coenurosis, leading to concerns about a possible concurrent increased risk of human CE. The aim of this study was to estimate the prevalence of human abdominal CE and the prevalence and species/genotypes of E. granulosus s.l. in livestock in Maasai communities. Methods: Human CE was diagnosed by abdominal ultrasound on volunteers aged ≥ 7 years in five villages in the Longido and Ngorongoro Districts in northern Tanzania. Infection in ruminants was evaluated through inspection in local abattoirs, followed by molecular identification of one cyst per animal, with a priority for hepatic cysts, using PCR targeting of the cytochrome c oxidase I gene (COX1), followed by restriction fragment length polymorphism and multiplex PCR, and sequencing of non-E. granulosus s.l. samples. Results: Ultrasound was performed on 823 volunteers (n = 352 in two villages in Longido District, and n = 471 in three villages of Ngorongoro). Hepatic CE cases were diagnosed only in Ngorongoro (n = 6; 1.3%), of which three had active cysts. Village-level prevalence of CE ranged between 0 and 2.4%. Of the 697 ruminants inspected, 34.4% had parasitic cysts. Molecular identification was achieved for 140 of the 219 (63.9%) cysts sampled. E. granulosus s.l. and T. hydatigena/Cysticercus tenuicollis were identified in 51.4% and 48.6%, respectively, of livestock cysts. E. granulosus s.l. was identified in livestock from both Longido (35.3% of 116 genotyped cysts) and Ngorongoro (91.2% of 34 genotyped cysts). Of the total of 72 E. granuslosus s.l. cysts identified in livestock, 87.5% were E. granulosus sensu stricto (G1–G3 genotypes), 9.7% were E. ortleppi (G5) and one cyst was E. canadensis (G6–10). The three active human cysts, which were removed surgically, were G1–G3 genotypes. Conclusions: Multiple species/genotypes of E. granulosus s.l. are circulating in Maasai communities of northern Tanzania. Human CE was detected in villages of Ngorongoro District and a high prevalence of echinococcal cysts was observed in livestock in both districts. More precise estimation of the prevalence in this area and a better understanding of the specific risk factors for CE among Maasai communities in northern Tanzania is needed. Interventions targeting transmission routes common to both E. granulosus s.l. and T. multiceps would have dual benefits for preventing both human and livestock disease

Waves of endemic foot-and-mouth disease in eastern Africa suggest feasibility of proactive vaccination approaches

Livestock production in Africa is key to national economies, food security and rural livelihoods, and > 85% of livestock keepers live in extreme poverty. With poverty elimination central to the Sustainable Development Goals, livestock keepers are therefore critically important. Foot-and-mouth disease is a highly contagious livestock disease widespread in Africa that contributes to this poverty. Despite its US$2.3 billion impact, control of the disease is not prioritized: standard vaccination regimens are too costly, its impact on the poorest is underestimated, and its epidemiology is too weakly understood. Our integrated analysis in Tanzania shows that the disease is of high concern, reduces household budgets for human health, and has major impacts on milk production and draft power for crop production. Critically, foot-and-mouth disease outbreaks in cattle are driven by livestock-related factors with a pattern of changing serotype dominance over time. Contrary to findings in southern Africa, we find no evidence of frequent infection from wildlife, with outbreaks in cattle sweeping slowly across the region through a sequence of dominant serotypes. This regularity suggests that timely identification of the epidemic serotype could allow proactive vaccination ahead of the wave of infection, mitigating impacts, and our preliminary matching work has identified potential vaccine candidates. This strategy is more realistic than wildlife-livestock separation or conventional foot-and-mouth disease vaccination approaches. Overall, we provide strong evidence for the feasibility of coordinated foot-and-mouth disease control as part of livestock development policies in eastern Africa, and our integrated socioeconomic, epidemiological, laboratory and modelling approach provides a framework for the study of other disease systems

Aquaglyceroporin-null trypanosomes display glycerol transport defects and respiratory-inhibitor sensitivity

Aquaglyceroporins (AQPs) transport water and glycerol and play important roles in drug-uptake in pathogenic trypanosomatids. For example, AQP2 in the human-infectious African trypanosome, Trypanosoma brucei gambiense, is responsible for melarsoprol and pentamidine-uptake, and melarsoprol treatment-failure has been found to be due to AQP2-defects in these parasites. To further probe the roles of these transporters, we assembled a T. b. brucei strain lacking all three AQP-genes. Triple-null aqp1-2-3 T. b. brucei displayed only a very moderate growth defect in vitro, established infections in mice and recovered effectively from hypotonic-shock. The aqp1-2-3 trypanosomes did, however, display glycerol uptake and efflux defects. They failed to accumulate glycerol or to utilise glycerol as a carbon-source and displayed increased sensitivity to salicylhydroxamic acid (SHAM), octyl gallate or propyl gallate; these inhibitors of trypanosome alternative oxidase (TAO) can increase intracellular glycerol to toxic levels. Notably, disruption of AQP2 alone generated cells with glycerol transport defects. Consistent with these findings, AQP2-defective, melarsoprol-resistant clinical isolates were sensitive to the TAO inhibitors, SHAM, propyl gallate and ascofuranone, relative to melarsoprol-sensitive reference strains. We conclude that African trypanosome AQPs are dispensable for viability and osmoregulation but they make important contributions to drug-uptake, glycerol-transport and respiratory-inhibitor sensitivity. We also discuss how the AQP-dependent inverse sensitivity to melarsoprol and respiratory inhibitors described here might be exploited

Comparative genomics of drug resistance in <i>Trypanosoma brucei rhodesiense</i>

Trypanosoma brucei rhodesiense is one of the causative agents of human sleeping sickness, a fatal disease that is transmitted by tsetse flies and restricted to Sub-Saharan Africa. Here we investigate two independent lines of T. b. rhodesiense that have been selected with the drugs melarsoprol and pentamidine over the course of 2 years, until they exhibited stable cross-resistance to an unprecedented degree. We apply comparative genomics and transcriptomics to identify the underlying mutations. Only few mutations have become fixed during selection. Three genes were affected by mutations in both lines: the aminopurine transporter AT1, the aquaporin AQP2, and the RNA-binding protein UBP1. The melarsoprol-selected line carried a large deletion including the adenosine transporter gene AT1, whereas the pentamidine-selected line carried a heterozygous point mutation in AT1, G430R, which rendered the transporter non-functional. Both resistant lines had lost AQP2, and both lines carried the same point mutation, R131L, in the RNA-binding motif of UBP1. The finding that concomitant deletion of the known resistance genes AT1 and AQP2 in T. b. brucei failed to phenocopy the high levels of resistance of the T. b. rhodesiense mutants indicated a possible role of UBP1 in melarsoprol-pentamidine cross-resistance. However, homozygous in situ expression of UBP1-Leu(131) in T. b. brucei did not affect the sensitivity to melarsoprol or pentamidine

One Health contributions towards more effective and equitable approaches to health in low- and middle-income countries

This research was supported by the UK Biotechnology and Biological Sciences Research Council (BB/J010367/1) and the UK Zoonoses and Emerging Livestock Systems Initiative (BB/L017679/1, BB/L018926/1 and BB/L018845/1) (S.C., J.E.B.H., J.S., J.B., A.D., J.A.C., W.A.d.G., R.R.K., T.K., D.T.H., B.T.M., E.S.S., L.W.). The Wellcome Trust provided supported for K.H. and A.L. (095787/Z/11/Z) and K.J.A. (096400/Z/11/Z). The US National Institutes of Health provided support for J.A.C. (R01AI121378) and M.P.R. (R01AI121378, K23AI116869).Emerging zoonoses with pandemic potential are a stated priority for the global health security agenda, but endemic zoonoses also have a major societal impact in low-resource settings. Although many endemic zoonoses can be treated, timely diagnosis and appropriate clinical management of human cases is often challenging. Preventive ‘One Health’ interventions, e.g. interventions in animal populations that generate human health benefits, may provide a useful approach to overcoming some of these challenges. Effective strategies, such as animal vaccination, already exist for the prevention, control and elimination of many endemic zoonoses, including rabies, and several livestock zoonoses (e.g. brucellosis, leptospirosis, Q fever) that are important causes of human febrile illness and livestock productivity losses in low- and middle-income countries. We make the case that, for these diseases, One Health interventions have the potential to be more effective and generate more equitable benefits for human health and livelihoods, particularly in rural areas, than approaches that rely exclusively on treatment of human cases. We hypothesize that applying One Health interventions to tackle these health challenges will help to build trust, community engagement and cross-sectoral collaboration, which will in turn strengthen the capacity of fragile health systems to respond to the threat of emerging zoonoses and other future health challenges. One Health interventions thus have the potential to align the ongoing needs of disadvantaged communities with the concerns of the broader global community, providing a pragmatic and equitable approach to meeting the global goals for sustainable development and supporting the global health security agenda.Publisher PDFPeer reviewe