Browsing by Author "Semango, George"

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Economic Burden of Livestock Abortions in Northern Tanzania
(Cambridge University press, 2024) Semango, George; Yoder, Jonathan; Kibona, Tito; Claxton, John; Buza, Joram; Mmbaga, Blandina; Johnson, Stephanie; Cleaveland, Sarah; Lankester, Felix
Livestock abortion is a source of economic loss for farmers, but its economic impact has not been estimated in many Low and Middle-Income Countries. This article presents an estimation methodology and estimates for the gross and net cost of an abortion based on a sample of livestock-owning households in three regions of northern Tanzania and market data. We then generate aggregate estimates of abortion losses across Tanzania. We estimate annual gross and net annual losses of about $263 Million (about TZS 600 billion) and $131 million (about TZS 300 billion), respectively.
Expression analysis of p16 and TOP2A protein biomarkers in cervical cancer lesions and their correlation with clinico-histopathological characteristics in a referral hospital, Tanzania
(PLOS ONE, 2021-10-27) Zuberi, Zavuga; Mremi, Alex; Chilongola, Jaffu; Semango, George; Sauli, Elingarami
Introduction Biomarkers yield important information for early diagnosis of cervical cancer. However, they are rarely applied for prognosis of cervical cancer in Tanzania, where visual inspection assay with acetic acid or Lugol’s iodine and Pap test are being used as the standard screening/ diagnostic methods. Methods This was a retrospective hospital-based cross-sectional study that was conducted to assess cyclin-dependent kinase inhibitor (p16) and topoisomerase II-alpha (TOP2A) proteins expression among women seeking cervical cancer care at Kilimanjaro Christian Medical Centre, Tanzania between May 1, 2017 and May 10, 2018. Immunohistochemistry technique was used to detect the expressions of p16 and TOP2A proteins from the retrieved formalin-fixed and paraffin-embedded (FFPE) cervical biopsies. Results A total of 145 patients, with a mean age of 52.1 ± 12.9 years, were included in this study. Upon immunohistochemistry staining, 103 (71.0%) and 90 (62.1%) were p16 and TOP2A positive respectively. There was a strong association between histopathological class and p16/TOP2A expression levels (Fisher’s exact test, p<0.001). Moreover, there was a strong positive correlation between p16/TOP2A and cancerous cervical lesions (Spearman’s rank correlation coefficients = 0.833 and 0.687, p = 0.006 and 0.005, respectively). The ageadjusted odds ratio for predicting cervical cancer lesions were independently significant for p16/TOP2A biomarkers in FFPE cervical tissues [p16: OR = 1.142 (95% CI: 1.059–1.232, p<0.001) and TOP2A: OR = 1.046 (95% CI: 1.008–1.085, p = 0.015)]. Importantly, thediagnostic performance of p16 was higher than that of TOP2A in the diagnosis of cancerous lesions from non-cancerous cervical lesions (sensitivity: 97.2% versus 77.6%, accuracy: 92.8% versus 87.8%, respectively). Conclusion Our study has highlighted that over-expression of TOP2A is related to the grade of cervical intraepithelial neoplasia but does not predict prognosis in cervical cancer. Similarly, expression of p16 is related to degree of histological dysplasia and malignancy, suggesting its prognostic and predictive value in the management of cervical cancers. Further bigger studies are needed to validate their applications in the early diagnosis of cervical cancer.
Prevalence and associated risk factors for Kaposi’s sarcoma among HIV-positive patients in a referral hospital in Northern Tanzania: a retrospective hospital-based study
(BMC, 2018-12-17) Semango, George; Charles, Renard; Swai, Consolata; Mremi, Alex; Amsi, Patrick; Sonda, Tolbert; Shao, Elichilia; Mavura, Daudi; Joosten, Leo; Sauli, Elingarami; Nyindo, Mramba
Background Kaposi’s sarcoma (KS) is a multifocal angioproliferative tumor involving blood and lymphatic vessels, caused by Human Herpes Virus-8 (HHV-8). KS is an important AIDS-defining tumor with high prevalence in Sub-Saharan Africa, including Tanzania which has high HIV and HHV-8 sero-prevalence. It is critically important to monitor the prevalence of AIDS-defining tumors, such as KS, in the age of HIV/AIDS. We studied the prevalence of KS and associated risk factors among HIV-positive patients at Kilimanjaro Christian Medical Centre (KCMC), a referral hospital in northern Tanzania, over the period from January 2012 to December 2015. Methods This was a retrospective hospital-based cross-sectional study to determine the prevalence of KS among HIV/AIDS patients between 2012 and 2015. The study included 1100 HIV patients’ data which were collected at the Infectious Disease Clinic (IDC) from patients’ files. Stata version 13 (StataCorp LP, Texas 77,845 USA) was used for all statistical analyses. The prevalence of KS was calculated across levels of a number of categorical variables. Logistic regression was performed to determine relative risk of KS for all characteristics. We included all variables with p-values ≤10% in the multivariate analysis, including ART use, as this is considered to have an influence on KS. In the multivariate analysis, statistical significance was established based on a two-tailed p-value ≤5%. All patients’ notes were kept confidential as per the Helsinki declaration. Results Our results revealed a 4.6% prevalence of KS at KCMC hospital, between January 2012 and December 2015, 51(4.6%) patients were diagnosed with KS out of 1100 HIV-positive patients. The study further revealed that KS in HIV patients was most associated with low CD4 cell count (less than or equal to 200 cells/μl). Moreover, women were more likely than men to diagnosed with KS, with higher odds significantly associated with KS (OR 0.42, p < 0.009). Increased age, above 35 years, among the HIV seropositive patients was significantly associated with KS (OR 25.67, p < 0.007). HIV patients who were none smokers were more likely to suffer from KS compared to HIV smokers (OR 0.41, p < 0.010). Conclusion KS remains a common malignant vascular tumor commonly associated with HIV/AIDS in Tanzania. Our study highlights the need for continued efforts to combat HIV, as well as associated diseases such as KS. Continued availability of ART (Anti-Retroviral Therapy) to HIV/AIDS patients, and test reagents for CD4 cell count and viral load determination are important measures to alleviate the suffering of these patients. Furthermore, studies to gather more evidence on ART resistance are highly needed to guide treatment choices.
Prospective cohort study reveals unexpected aetiologies of livestock abortion in northern Tanzania
(Springer Nature Limited, 2022-07-08) Thomas, Kate; Kibona, Tito; Claxton, John; de Glanville, William; Lankester, Felix; Amani, Nelson; Buza, Joram; Carter, Ryan; Chapman, Gail; Crump, John; Dagleish, Mark; Halliday, Jo; Hamilton, Clare; Innes, Elisabeth; Katzer, Frank; Livingstone, Morag; Longbottom, David; Millins, Caroline; Mmbaga, Blandina; Mosha, Victor; Nyarobi, James; Nyasebwa, Obed; Russell, George; Sanka, Paul; Semango, George; Wheelhouse, Nick; Willett, Brian; Cleaveland, Sarah; Allan, Kathryn
Livestock abortion is an important cause of productivity losses worldwide and many infectious causes of abortion are zoonotic pathogens that impact on human health. Little is known about the relative importance of infectious causes of livestock abortion in Africa, including in subsistence farming communities that are critically dependent on livestock for food, income, and wellbeing. We conducted a prospective cohort study of livestock abortion, supported by cross-sectional serosurveillance, to determine aetiologies of livestock abortions in livestock in Tanzania. This approach generated several important findings including detection of a Rift Valley fever virus outbreak in cattle; high prevalence of C. burnetii infection in livestock; and the first report of Neospora caninum, Toxoplasma gondii, and pestiviruses associated with livestock abortion in Tanzania. Our approach provides a model for abortion surveillance in resource-limited settings. Our findings add substantially to current knowledge in sub-Saharan Africa, providing important evidence from which to prioritise disease interventions.
Review of the Current Status on Livestock Abortigenic Diseases Surveillance in Africa and Asia
(Preprints, 2024-03-08) Semango, George; Buza, Joram
Introduction: Livestock abortigenic agents, which are microorganisms that lead to premature foetal death and expulsion before completion of the gestation period, are common in Africa and Asia. Abortion events cause economic losses by lowering reproduction (and hence herd/flock sizes) and effects on milk production. Despite the importance of livestock production for food security and livelihoods of millions of the world’s poorest communities, very little is known about the scale, magnitude or causes of livestock abortion in Africa. The aim of this review was to determine the current status of the burden of livestock abortion and surveillance measures adopted for livestock abortigenic pathogens in Africa and Asia, and to explore feasible surveillance technologies. Methodology: A systematic literature search was conducted using Preferred Reporting of Systematic Reviews and Meta-analyses (PRISMA) guidelines in four databases for studies published between 1 Jan 1990 and 31 July 2021 that reported epidemiological surveys of livestock abortigenic pathogens in cattle, goats and sheep in Africa and Asia including; Brucella spp., Neospora caninum, Toxoplasma gondii, Rift valley fever virus, Coxiella burnetii, Chlamydia, Leptospira and Bovine viral Diarrhoea Virus. A meta-analysis was used to estimate the species-specific prevalence of the abortigenic diseases and the region where they were detected. Results: In the systematic literature search, 48 full papers were included which in total included 50 species-specific surveillance reports from Africa and 19 from Asia. Adjusted median seroprevalence calculations estimated Brucella at 6.85% (range 1.2-11.6) of 9071 sheep, 3.35% (range 0.90-5.40) of 17,007 goats, 8.95% (range 0.50-63.60) of 171,733 cattle, Neospora at 6.80% (range 6.80 -6.80) of 555 sheep, 10.80 (range 10.80-10.80) of 185 goats, 12.65% (range 3.40- 25.60) of 3775 cattle, Toxoplasma at 27.50% (range 1.40 – 75.90) of 2284 sheep, 32.0% (range 20.00- 64.80) of 1226 goats, 7.50% (range 7.50 - 7.50) of 174 cattle, Coxiella at 9.20 (range 9.20 – 9.20) of 184 sheep, 24.20% (range 24.20-24.20) of 91 goats, 13.80% (range 13.80-13.80) of 217 cattle, Rift valley fever virus at 7.70 (2.40-40.00) of 874 sheep, 20.95 (range 2.50-40.00) of 547 goats, 7.45% (range 3.60-11.30) of 309 cattle, Bovine viral diarrhea virus at 78.90 (range 78.90 – 78.90) of 398 cattle, Leptospira at 70.50 (range 70.50 – 70.50) of 373 cattle and Chlamydia at 6.60 (6.60-6.60) of 803 sheep. We found that most studies, 45 (89%) used serological surveys, 1 (2%) used molecular and 1 (2%) reported to have used Mobile-phone based surveillance approach. Three studies (6.25%) of the 48 included were embedded in the national surveillance programs of the respective countries they were conducted, majority 89% were stand-alone cross- sectional studies. Conclusion :In conclusion, livestock abortigenic pathogens are still a burden in many African and Asian countries.
Review of the Current Status on Livestock Abortigenic Diseases Surveillance in Africa and Asia.
(Pre prints.org, 2024-03-08) Semango, George; Buza, Joram
Introduction: Livestock abortigenic agents, are microorganisms that lead to premature foetal death and expulsion before completion of the gestation period, are common in Africa and Asia. Abortion events cause economic losses by lowering reproduction (and hence herd/flock sizes) and effects on milk production. Despite the importance of livestock production for food security and livelihoods of millions of the world’s poorest communities, very little is known about the scale, magnitude or causes of livestock abortion in Africa. The aim of this review was to determine the current status of the burden of livestock abortion and surveillance measures adopted for livestock abortigenic pathogens in Africa and Asia, and to explore feasible surveillance technologies. Methodology: A systematic literature search was conducted using Preferred Reporting of Systematic Reviews and Meta-analyses (PRISMA) guidelines in four databases for studies published between 1 Jan 1990 and 31 July 2021 that reported epidemiological surveys of livestock abortigenic pathogens in cattle, goats and sheep in Africa and Asia including; Brucella spp., Neospora caninum, Toxoplasma gondii, Rift valley fever virus, Coxiella burnetii, Chlamydia, Leptospira and Bovine viral Diarrhoea Virus. A meta-analysis was used to estimate the species-specific prevalence of the abortigenic diseases and the region where they were detected. Results: In the systematic literature search, 48 full papers were included which in total included 50 species-specific surveillance reports from Africa and 19 from Asia. Adjusted median seroprevalence calculations estimated Brucella at 6.85% (range 1.2-11.6) of 9071 sheep, 3.35% (range 0.90-5.40) of 17,007 goats, 8.95% (range 0.50-63.60) of 171,733 cattle, Neospora at 6.80% (range 6.80 -6.80) of 555 sheep, 10.80 (range 10.80-10.80) of 185 goats, 12.65% (range 3.40- 25.60) of 3775 cattle, Toxoplasma at 27.50% (range 1.40 – 75.90) of 2284 sheep, 32.0% (range 20.00- 64.80) of 1226 goats, 7.50% (range 7.50 - 7.50) of 174 cattle, Coxiella at 9.20 (range 9.20 – 9.20) of 184 sheep, 24.20% (range 24.20-24.20) of 91 goats, 13.80% (range 13.80-13.80) of 217 cattle, Rift valley fever virus at 7.70 (2.40-40.00) of 874 sheep, 20.95 (range 2.50-40.00) of 547 goats, 7.45% (range 3.60-11.30) of 309 cattle, Bovine viral diarrhea virus at 78.90 (range 78.90 – 78.90) of 398 cattle, Leptospira at 70.50 (range 70.50 – 70.50) of 373 cattle and Chlamydia at 6.60 (6.60-6.60) of 803 sheep. We found that in most studies, 45 (89%) used serological surveys, 1 (2%) used molecular and 1 (2%) reported to have used Mobile-phone based surveillance approach. Three studies (6.25%) of the 48 included were embedded in the national surveillance programs of the respective countries they were conducted, the majority 89% were stand-alone cross sectional studies. Conclusion: In conclusion, livestock abortigenic pathogens are still a burden in many African and Asian countries.
Review of the Current Status on Ruminant Abortigenic Pathogen Surveillance in Africa and Asia
(MDPI, 2024-09-12) Semango, George; Buza, Joram
Ruminant abortion events cause economic losses. Despite the importance of livestock production for food security and the livelihoods of millions of people in the world’s poorest communities, very little is known about the scale, magnitude, or causes of these abortions in Africa and Asia. The aim of this review was to determine the current status of surveillance measures adopted for ruminant abortigenic pathogens in Africa and Asia and to explore feasible surveillance technologies. A systematic literature search was conducted using PRISMA guidelines for studies published between 1 January 1990 and 1 May 2024 that reported epidemiological surveys of abortigenic pathogens Africa and Asia. A meta-analysis was used to estimate the species-specific sero-prevalence of the abortigenic agents and the regions where they were detected. In the systematic literature search, 39 full-text manuscripts were included. The most prevalent abortigenic pathogens with sero-prevalence greater than 10% were BHV-1, Brucella, Chlamydia abortus, Neospora caninum, RVFV, and Waddlia chondrophila in cattle, BVDV in sheep, and RVFV and Toxoplasma gondii in goats in Africa. In Asia, Anaplasma, BHV-1, Bluetongue virus, Brucella, and BVDV were prevalent in cattle, whereas Mycoplasma was important in goats and sheep.
The Sero-epidemiology of Neospora caninum in Cattle in Northern Tanzania
(Frontiers in Veterinary Science, 2019-09-26) Semango, George; Hamilton, Clare; Kreppel, Katharina; Katzer, Frank; Kibona, Tito; Lankester, Felix; Allan, Kathryn; Thomas, Kate; Claxton, John; Innes, Elizabeth; Swai, Emmanuel; Buza, Joram; Cleaveland, Sarah; de Glanville, William
Neospora caninum is a protozoan intracellular parasite of animals with a global distribution. Dogs act as definitive hosts, with infection in cattle leading to reproductive losses. Neosporosis can be a major source of income loss for livestock keepers, but its impacts in sub-Saharan Africa are mostly unknown. This study aimed to estimate the seroprevalence and identify risk factors for N. caninum infection in cattle in northern Tanzania, and to link herd-level exposure to reproductive losses. Serum samples from 3,015 cattle were collected from 380 households in 20 villages between February and December 2016. Questionnaire data were collected from 360 of these households. Household coordinates were used to extract satellite derived environmental data from open-access sources. Sera were tested for the presence of N. caninum antibodies using an indirect ELISA. Risk factors for individual-level seropositivity were identified with logistic regression using Bayesian model averaging (BMA). The relationship between herd-level seroprevalence and abortion rates was assessed using negative binomial regression. The seroprevalence of N. caninum exposure after adjustment for diagnostic test performance was 21.5% [95% Credibility Interval (CrI) 17.9–25.4]. The most important predictors of seropositivity selected by BMA were age greater than 18months [Odds ratio (OR) = 2.17, 95% CrI 1.45–3.26], the local cattle population density (OR = 0.69, 95% CrI 0.41–1.00), household use of restricted grazing (OR = 0.72, 95% CrI 0.25–1.16), and an increasing percentage cover of shrub or forest land in the environment surrounding a household (OR = 1.37, 1.00–2.14). There was a positive relationship between herd-level N. caninum seroprevalence and the reported within-herd abortion rate (Incidence Rate Ratio = 1.03, 95% CrI 1.00–1.06). Our findings suggest N. caninum is likely to be an important cause of abortion in cattle in Tanzania. Management practices, such as restricted grazing, are likely to reduce the risk of infection and suggest contamination of communal grazing areas may be important for transmission. Evidence for a relationship between livestock seropositivity and shrub and forest habitats raises questions about a potential role for wildlife in the epidemiology of N. caninum in Tanzania.