Browsing by Author "Sindato, Calvin"

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Circulation of dengue serotype 1 viruses during the 2019 outbreak in Dar es Salaam, Tanzania
(Informa UK Limited, trading as Taylor & Francis Group., 2021) Mwanyika, Gaspary O.; Mboera, Leonard E. G.; Rugarabamu, Sima; Makange, Mariam; Sindato, Calvin; Lutwama, Julius J.; Paweska, Janusz T.; Misinzo, Gerald
Dengue is an important mosquito-borne viral disease in humans in tropical and subtropical countries. In 2019, a total of 6917 dengue cases were reported in Tanzania based on serological analysis. The aim of this study was to confirm the presence of dengue virus (DENV) and conduct its genetic characterization. A total of 191 serum samples were collected from the outpatients seeking care from health facilities in Kinondoni and Ilala districts between March and May 2019. All the samples were initially tested for the presence of non-structural protein 1 and anti-DENV immunoglobulin G (IgG) and IgM using a commercial OnSite Duo Dengue Ag-IgG/IgM rapid test. Of the 191 sera, 110 (57.6%) were DENV seropositive. The presence of DENV ribonucleic acid was confirmed in 18.2% of the seropositive sera by reverse transcription polymerase chain reaction (RT-PCR). The RT-PCR products were cleaned and partial sequences of DENV poly protein gene determined using dideoxynucleotide cycle sequencing followed by phylogenetic analysis. We present the occurrence of DENV serotype 1 (DENV-1) during the 2019 outbreak in Tanzania. The DENV-1 strains reported in the present study are highly identical and cluster with Asian DENV-1 strains indicating the possibility of intercontinental spread of DENV through globalization. We advocate for the need for molecular surveillance of dengue viruses during outbreaks to provide rapid evidence of the disease to guide public health interventions.
Dengue virus infection and associated risk factors in Africa: a systematic review and meta-analysis
(MDPI, 2021) Mwanyika, Gaspary O.; Mboera, Leonard E. G.; Rugarabamu, Sima; Ngingo, Baraka; Sindato, Calvin; Lutwama, Julius J.; Paweska, Janusz T.; Misinzo, Gerald
Dengue contributes a significant burden on global public health and economies. In Africa, the burden of dengue virus (DENV) infection is not well described. This review was undertaken to determine the prevalence of dengue and associated risk factors. A literature search was done on PubMed/MEDLINE, Scopus, Embase, and Google Scholar databases to identify articles published be- tween 1960 and 2020. Meta-analysis was performed using a random-effect model at a 95% confidence interval, followed by subgroup meta-analysis to determine the overall prevalence. Between 1960 and 2020, 45 outbreaks were identified, of which 17 and 16 occurred in East and West Africa, respectively. Dengue virus serotype 1 (DENV-1) and DENV-2 were the dominant serotypes contributing to 60% of the epidemics. Of 2211 cases reported between 2009 and 2020; 1954 (88.4%) were reported during outbreaks. Overall, the prevalence of dengue was 29% (95% CI: 20–39%) and 3% (95% CI: 1–5%) during the outbreak and non-outbreak periods, respectively. Old age (6/21 studies), lack of mosquito control (6/21), urban residence (4/21), climate change (3/21), and recent history of travel (3/21) were the leading risk factors. This review reports a high burden of dengue and increased risk of severe disease in Africa. Our findings provide useful information for clinical practice and health policy decisions to implement effective interventions.
The epidemiology and socio-economic impact of rift valley fever epidemics in Tanzania: a review
(Tanzania Journal of Health Research, 2011) Sindato, Calvin; Karimuribo, Esron; Mboera, Leonard E.G
Rift Valley Fever (RVF) is an acute, mosquito-borne viral disease that has a significant global threat to humans and livestock. This review was conducted to provide comprehensive update on Rift Valley Fever (RVF) in Tanzania, with particular attention devoted to trend of occurrence, epidemiological factors, socioeconomic impact and measures which were applied to its control. Information presented in this paper was obtained through extensive literature review. RVF occurred for the first time in Tanzania in 1930. This was followed by periodic epidemics of 10-20 years i.e. 1947, 1957, 1977, 1997 and 2007. During the latest disease outbreak in 2007 (the expanded to cover wider area of the country) 52.4% (n=21) of regions in Tanzania mainland were affected and majority (72.7%, n=11) of the regions had concurrent infections in human and animals. Phylogenetic comparison of nucleotide and amimo acid sequences revealed different virus strains between Kenya and Tanzania. Epidemiological factors that were considered responsible for the previous RVF epidemics in Tanzania included farming systems, climatic factors, vector activities and presence of large population of ruminant species, animal movements and food consumption habits. The disease caused serious effects on rural people’s food security and household nutrition and on direct and indirect losses to livestock producers in the country. Psycho-social distress that communities went through was enormous, which involved the thinking about the loss of their family members and/or relatives, their livestock and crop production. Socially, the status of most livestock producers was eroded in their communities. Steps taken to combat epidemics included restriction of animal movements, ban of the slaughter of domestic ruminants and vaccination of livestock and health education.
Leveraging sub-national collaboration and influence for improving animal health surveillance and response: a stakeholder mapping in Tanzania
(Frontiers in Veterinary Science, 2021-12-13) George, Janeth; Häsler, Barbara; Komba, Erick V. G.; Sindato, Calvin; Rweyemamu, Mark; Kimera, Sharadhuli I.; Mlangwa, James E. D.
Animal health surveillance plays a vital role in ensuring public health, animal welfare, and sustainable food production by monitoring disease trends, early detecting (new) hazards, facilitating disease control and infection, and providing data for risk analysis. Good stakeholder collaboration across the sector can lead to better communication, better science and decision-making and more effective surveillance and response. An understanding of relevant stakeholders, their interests and their power can facilitate such collaboration. While information on key stakeholders in animal health surveillance is available at the national level in Tanzania, it is missing at the subnational level. The study aimed to explore the existing stakeholders’ collaborations and influences at the subnational level through stakeholder mapping and to determine potential leverage points for improving the national animal health surveillance system. A qualitative design was used, involving consultative workshops with government animal health practitioners in Sumbawanga, Sikonge and Kilombero districts of Tanzania from December 2020 to January 2021. Data were collected using an adapted USAID stakeholder collaboration mapping tool with the following steps: (i) Define the objective (ii) Identify all stakeholders (iii) Take stock of the current relationships (iv) Determine resource-based influence (v) Determine non-resource based influence and (vi) Review and revise the collaboration map. Forty-five stakeholders were identified in all three districts and grouped into four categories: private sector and non-government organizations (n = 16), government (n = 16), community (n = 9) and political leaders (n = 4). Animal health practitioners had a stronger relationship with community stakeholders as compared to other categories. The results also showed that most of the stakeholders have non-resource-based influence compared to resource-based influence. The private sector and non-government organizations have a relatively higher number of resource-based influential stakeholders, while political leaders have more non-resource-based influence. The mapping exercise demonstrated that the system could benefit from community mobilization and sensitization, resource mobilization and expanding the horizon of surveillance data sources. Some of the leverage points include integration of surveillance activities into animal health services, clear operational processes, constant engagement, coordination and incentivization of stakeholders. The diversity in the identified stakeholders across the districts suggests that collaborations are contextual and socially constructed.
Rift valley fever risk mapping and modelling in Tanzania
(Sokoine University of Agriculture, 2015) Sindato, Calvin
Rift Valley fever (RVF) was first reported in Tanzania in 1930 and the last outbreak occurred in the country in 2006/07. Besides the long history of RVF in the country, little is known about its spatial and temporal epidemiology and habitat suitability for its occurrence. This study was conducted to determine potential risk factors and develop the country RVF risk map. Enzyme-linked immunosorbent assay was used to examine the presence of antibodies specific to RVF virus (RVFV) in serum samples from domestic ruminants, humans and wild animals. Logistic regression modelling was used to analyze RVF outbreak data and RVFV seropositivity. Space-time permutation and MaxEnt modelling were used to identify clusters and habitat suitability for RVF occurrence, respectively. Between 1930 and 2007, there were a total of 10 RVF outbreaks with overlapping of clusters that continuously covered more parts of the country. Overall, the seroprevalence of IgG specific to RVFV in domestic ruminants (n = 1435) was 25.8% (95% CI: 23.52, 28.05) and in humans (n = 541) was 10.7% (95% CI: 8.11, 13.34). The IgG specific to RVFV was detected in nine (n = 22) and one (n = 3) serum samples from African buffalo and African elephant, respectively. The potential risk factors for RVF occurrence included eastern Rift Valley ecosystem (OR = 6.14, CI: 1.96, 19.28), rainfall during the previous two months >405.4mm (OR = 12.36, CI: 3.06, 49.88), clay (OR =8.76, CI: 2.5, 30.5) and loam (OR = 8.8, CI: 2.0, 37.8) soil texture, introduction of domestic ruminants into the herd (OR = 5.08, CI: 2.74, 9.44; p< 0.001), human contact with aborted foetus materials (OR = 2.89, CI: 1.48, 5.60), human participation in the slaughtering of animals (OR = 2.65, CI: 1.39, 5.04), human having consumed meat from dead animals (OR = 2.06, CI: 1.05, 4.00). The findings of this study have shown that the north-eastern, central and lake zones of the country have larger amount of suitable habitat for RVF occurrence than the north-western and southern zones. These research findingsiii can be applied to guide risk-based cost-effective RVF surveillance and interventions strategies in the country.
Seroprevalence and associated risk factors of chikungunya, dengue, and zika in eight districts in Tanzania
(Elsevier Ltd, 2021) Mwanyika, Gaspary O.; Sindato, Calvin; Rugarabamu, Sima; Rumisha, Susan F.; Karimuribo, Esron D.; Misinzo, Gerald; Rweyemamu, Mark M.; Hamid, Muzamil M. Abdel; Haider, Najmul; Vairo, Francesco; Kock, Richard; Mboera, Leonard E.G.
Background: This study was conducted to determine the seroprevalence and risk factors of chikungunya (CHIKV), dengue (DENV), and Zika (ZIKV) viruses in Tanzania. Methods: The study covered the districts of Buhigwe, Kalambo, Kilindi, Kinondoni, Kondoa, Kyela, Mvomero, and Ukerewe in Tanzania. Blood samples were collected from individuals recruited from house- holds and healthcare facilities. An ELISA was used to screen for immunoglobulin G antibodies against CHIKV, DENV, and ZIKV. Results: A total of 1818 participants (median age 34 years) were recruited. The overall CHIKV, DENV, and ZIKV seroprevalence rates were 28.0%, 16.1%, and 6.8%, respectively. CHIKV prevalence was highest in Buhigwe (46.8%), DENV in Kinondoni (43.8%), and ZIKV in Ukerewe (10.6%) and Mvomero (10.6%). Increas- ing age and frequent mosquito bites were significantly associated with CHIKV and DENV seropositivity ( P < 0.05). Having piped water or the presence of stagnant water around the home ( P < 0.01) were as- sociated with higher odds of DENV seropositivity. Fever was significantly associated with increased odds of CHIKV seropositivity ( P < 0.001). Visiting mines had higher odds of ZIKV seropositivity ( P < 0.05). Conclusions: These findings indicate that DENV, CHIKV, and ZIKV are circulating in diverse ecological zones of Tanzania. There is a need to strengthen the control of mosquito-borne viral diseases in Tanzania.
A spatial analysis of Rift Valley Fever Virus seropositivity in domestic ruminants in Tanzania
(PLOS ONE, 2015-07-10) Sindato, Calvin; Pfeiffer, Dirk U.; Karimuribo, Esron D.; Mboera, Leonard E.G.; Rweyemamu, Mark M.; Paweska, Janusz T.
Rift Valley fever(RVF) is an acute arthropod-borne viral zoonotic disease primarily occurring in Africa.Since RVF-like disease was reported in Tanzaniain1930,outbreaks of the disease have been reported mainly from the eastern ecosystem of the Great Rift Valley. This cross-sectional study was carried out to describe the variation in RVF virus (RVFV) seropositivity in domestic ruminants between selected villages in the eastern and western Rift Valley ecosystems in Tanzania, and identify potential risk factors. Three study villages were purposively selected from each of the two Rift Valley ecosystems. Serum samples from randomly selected domestic ruminants (n=1,435) were tested for the presence of specific immunoglobulin G(IgG) and M(IgM) ,using RVF enzyme-linked immunosorbent assay methods .Mixed effects logistic regression modelling was used to investigate the association between potential risk factors and RVFV seropositivity. The overall RVFV seroprevalence (n=1,435) in domestic ruminants was 25.8% and species specific seroprevalence was 29.7%, 27.7% and 22.0% in sheep (n=148), cattle (n=756) and goats (n=531), respectively. The odds of seropositivity were significantly higher in animals sampled from the villages in the eastern than those in the western Rift Valley ecosystem (OR=1.88,CI: 1.41,2.51; p<0.001) , in animals sampled from villages with soils of good than those with soils of poor water holding capacity (OR=1.97; 95%CI:1.58,3.02;p<0.001), and in animals which had been introduced than in animals born within the herd (OR=5.08,CI:2.74, 9.44;p<0.001). Compared with animals aged 1–2 years, those aged 3 and 4–5 years had 3.40 (CI:2.49,4.64;p<0.001) and 3.31 (CI:2.27,4.82,p<0.001) times the odds of seropositivity. The findings confirm exposure to RVFV in all the study villages, but with a higher prevalence in the study villages from the eastern Rift Valley ecosystem.
Spatial and temporal pattern of Rift Valley fever outbreaks in Tanzania; 1930 to 2007
(Plos One, 2014) Sindato, Calvin; Karimuribo, Esron D.; Pfeiffer, Dirk U.
Background: Rift Valley fever (RVF)-like disease was first reported in Tanzania more than eight decades ago and the last large outbreak of the disease occurred in 2006–07. This study investigates the spatial and temporal pattern of RVF outbreaks in Tanzania over the past 80 years in order to guide prevention and control strategies. Materials and Methods: A retrospective study was carried out based on disease reporting data from Tanzania at district or village level. The data were sourced from the Ministries responsible for livestock and human health, Tanzania Meteorological Agency and research institutions involved in RVF surveillance and diagnosis. The spatial distribution of outbreaks was mapped using ArcGIS 10. The space-time permutation model was applied to identify clusters of cases, and a multivariable logistic regression model was used to identify risk factors associated with the occurrence of outbreaks in the district. Principal Findings: RVF outbreaks were reported between December and June in 1930, 1947, 1957, 1960, 1963, 1968, 1977– 79, 1989, 1997–98 and 2006–07 in 39.2% of the districts in Tanzania. There was statistically significant spatio-temporal clustering of outbreaks. RVF occurrence was associated with the eastern Rift Valley ecosystem (OR = 6.14, CI: 1.96, 19.28), total amount of rainfall of .405.4 mm (OR = 12.36, CI: 3.06, 49.88), soil texture (clay [OR = 8.76, CI: 2.52, 30.50], and loam [OR = 8.79, CI: 2.04, 37.82]). Conclusion/Significance: RVF outbreaks were found to be distributed heterogeneously and transmission dynamics appeared to vary between areas. The sequence of outbreak waves, continuously cover more parts of the country. Whenever infection has been introduced into an area, it is likely to be involved in future outbreaks. The cases were more likely to be reported from the eastern Rift Valley than from the western Rift Valley ecosystem and from areas with clay and loam rather than sandy soil texture.
Towards an integrated animal health surveillance system in Tanzania: making better use of existing and potential data sources for early warning surveillance
(BMC Veterinary Research, 2021) George, Janeth; Häsler, Barbara; Komba, Erick; Sindato, Calvin; Rweyemamu, Mark; Mlangwa, James
Background: Effective animal health surveillance systems require reliable, high-quality, and timely data for decision making. In Tanzania, the animal health surveillance system has been relying on a few data sources, which suffer from delays in reporting, underreporting, and high cost of data collection and transmission. The integration of data from multiple sources can enhance early detection and response to animal diseases and facilitate the early control of outbreaks. This study aimed to identify and assess existing and potential data sources for the animal health surveillance system in Tanzania and how they can be better used for early warning surveillance. The study used a mixed-method design to identify and assess data sources. Data were collected through document reviews, internet search, cross-sectional survey, key informant interviews, site visits, and non-participant observation. The assessment was done using pre-defined criteria. Results: A total of 13 data sources were identified and assessed. Most surveillance data came from livestock farmers, slaughter facilities, and livestock markets; while animal dip sites were the least used sources. Commercial farms and veterinary shops, electronic surveillance tools like AfyaData and Event Mobile Application (EMA-i) and information systems such as the Tanzania National Livestock Identification and Traceability System (TANLITS) and Agricultural Routine Data System (ARDS) show potential to generate relevant data for the national animal health surveillance system. The common variables found across most sources were: the name of the place (12/13), animal type/species (12/13), syndromes (10/13) and number of affected animals (8/13). The majority of the sources had good surveillance data contents and were accessible with medium to maximum spatial coverage. However, there was significant variation in terms of data frequency, accuracy and cost. There were limited integration and coordination of data flow from the identified sources with minimum to non-existing automated data entry and transmission. Conclusion: The study demonstrated how the available data sources have great potential for early warning surveillance in Tanzania. Both existing and potential data sources had complementary strengths and weaknesses; a multi-source surveillance system would be best placed to harness these different strengths.