Integrated disease surveillance and response systems in resource-limited settings

Infectious diseases are a major public health burden causing millions of deaths every year. Government authorities need to be able to monitor disease incidence and evaluate their interventions for disease control. Monitoring the status of infectious diseases is one of the most challenging problems facing the public health sector, and epidemiological surveillance systems for infectious diseases, particularly notifiable diseases are essential. Despite initiatives to encourage reporting of infectious diseases, underreporting and poor surveillance are on-going challenges for many developing countries. Most surveillance systems in these settings use traditional paper-based methods, which are both inefficient and impractical. There is a need for alternative tools to strengthen infectious disease surveillance systems in resource-limited settings. The remarkable progress made in mobile computing technology has the potential to improve infectious disease surveillance systems. However, user experience in digital technologies and infrastructure needs to be given greater attention. My study investigated the use of mobile phone devices as surveillance tools in health information systems. A mobile phone-based surveillance system was developed and applied in Tanzania as an alternative approach to traditional paper-based systems. Using this system different factors that affect the usability of mobile phone-based systems were investigated, by examining the quality of surveillance data in the context of completeness, timeliness and costs. After two years of operation in twenty-eight districts in southern Tanzania, numerous factors were identified that affect user accuracy and speed of use of the mobile phone-based surveillance. These include user experience in digital technology, particularly mobile device ownership; digital technology literacy, such as access and use of SMS and user’s age. The mobile phone-based surveillance system was more accurate compared to the traditional paper-based system with greater data reporting, more complete data and timelier reporting. Initially the mobile phone-based surveillance system required more capital investment, although the running costs of paper-based surveillance were greater. The utility of the mobile phone-based surveillance in monitoring and evaluating large-scale rabies control interventions was examined and the data produced was used to analyse the impacts of interventions on reducing disease incidence. Significant relationships were detected between the incidence of reported bite injuries in the focal district the previous month and in neighbouring districts that month, with more injuries detected in mainland Tanzania than on the island of Pemba. The relationship between bite injuries and vaccination coverage was complicated, with some evidence that vaccination reduced bite incidence. However, more data and a better model are needed to fully understand the impact of vaccination on bite incidence. The system provided timely information on the implementation of control measures and incidence of bite injuries, vital for improving control efforts. Use of automated short text messages (SMS) as part of the mobile phone-based surveillance was assessed to determine whether they could improve patient’s adherence to treatment regimens. Patients who received SMS reminders had significantly better compliance than those who did not, with attendance improved by at least 10%. Use of SMS reminders has the potential to improve patients’ compliance in other treatment regimens that require repeat clinic visits or administration of medicines. This thesis documented how the use of mobile phone devices can be used to improve surveillance in resource-limited settings. The use of effective integrated surveillance system could empower major stakeholders concerned with public health problems by providing them with appropriate real-time information on disease incidence and control interventions. In the final chapter the challenges encountered and insights gained in the application of mobile computing in strengthening infectious diseases surveillance are discussed. Despite infrastructural challenges such as unreliable power and Internet, mobile computing technologies can improve patient care and authorities can be prompted in a timely manner about infectious disease outbreaks and of supply shortages. In conclusion, innovative tools that can strengthen and integrate human and animal surveillance can improve the control and prevention of infectious diseases. Mobile phones have great potential for this, and can be used to strengthen health information systems

Estimating the size of dog populations in Tanzania to inform rabies control

Estimates of dog population sizes are a prerequisite for delivering effective canine rabies control. However, dog population sizes are generally unknown in most rabies-endemic areas. Several approaches have been used to estimate dog populations but without rigorous evaluation. We compare post-vaccination transects, household surveys, and school-based surveys to determine which most precisely estimates dog population sizes. These methods were implemented across 28 districts in southeast Tanzania, in conjunction with mass dog vaccinations, covering a range of settings, livelihoods, and religious backgrounds. Transects were the most precise method, revealing highly variable patterns of dog ownership, with human/dog ratios ranging from 12.4:1 to 181.3:1 across districts. Both household and school-based surveys generated imprecise and, sometimes, inaccurate estimates, due to small sample sizes in relation to the heterogeneity in patterns of dog ownership. Transect data were subsequently used to develop a predictive model for estimating dog populations in districts lacking transect data. We predicted a dog population of 2,316,000 (95% CI 1,573,000–3,122,000) in Tanzania and an average human/dog ratio of 20.7:1. Our modelling approach has the potential to be applied to predicting dog population sizes in other areas where mass dog vaccinations are planned, given census and livelihood data. Furthermore, we recommend post-vaccination transects as a rapid and effective method to refine dog population estimates across large geographic areas and to guide dog vaccination programmes in settings with mostly free roaming dog populations

Comparing methods of assessing dog rabies vaccination coverage in rural and urban communities in Tanzania

Rabies can be eliminated by achieving comprehensive coverage of 70% of domestic dogs during annual mass vaccination campaigns. Estimates of vaccination coverage are, therefore, required to evaluate and manage mass dog vaccination programs; however, there is no specific guidance for the most accurate and efficient methods for estimating coverage in different settings. Here, we compare post-vaccination transects, school-based surveys, and household surveys across 28 districts in southeast Tanzania and Pemba island covering rural, urban, coastal and inland settings, and a range of different livelihoods and religious backgrounds. These approaches were explored in detail in a single district in northwest Tanzania (Serengeti), where their performance was compared with a complete dog population census that also recorded dog vaccination status. Post-vaccination transects involved counting marked (vaccinated) and unmarked (unvaccinated) dogs immediately after campaigns in 2,155 villages (24,721 dogs counted). School-based surveys were administered to 8,587 primary school pupils each representing a unique household, in 119 randomly selected schools approximately 2 months after campaigns. Household surveys were conducted in 160 randomly selected villages (4,488 households) in July/August 2011. Costs to implement these coverage assessments were $12.01,$66.12, and $155.70 per village for post-vaccination transects, school-based, and household surveys, respectively. Simulations were performed to assess the effect of sampling on the precision of coverage estimation. The sampling effort required to obtain reasonably precise estimates of coverage from household surveys is generally very high and probably prohibitively expensive for routine monitoring across large areas, particularly in communities with high human to dog ratios. School-based surveys partially overcame sampling constraints, however, were also costly to obtain reasonably precise estimates of coverage. Post-vaccination transects provided precise and timely estimates of community-level coverage that could be used to troubleshoot the performance of campaigns across large areas. However, transects typically overestimated coverage by around 10%, which therefore needs consideration when evaluating the impacts of campaigns. We discuss the advantages and disadvantages of these different methods and make recommendations for how vaccination campaigns can be better monitored and managed at different stages of rabies control and elimination programs

Dr. Godfrey Mbaruku: A tribute and review of the life of a maternal health crusader in Tanzania

Dr. Godfrey Mbaruku, an obstetrician-gynecologist and one of Tanzania’s most dedicated maternal health researchers, passed away in September 2018. His professional career spanned over four decades, with the last decade of his life dedicated to maternal health research, advocacy and policy in Africa. We undertook a review of the key global milestones in maternal health policy, funding and research that took place during Dr. Mbaruku’s career until his untimely death in 2018. We then reflect on the progress of the maternal health agenda from 2018 to 2021 as lower middle income countries (LMICs) continue to strive to reach the sustainable development goals (SDGs) in the midst of a global pandemic. Dr. Godfrey Mbaruku’s commitment to improving maternal health in Tanzania through his advocacy and research contributions over his professional life will forever serve as foundational pillars for the ongoing global effort to reduce maternal mortality.   Le Dr Godfrey Mbaruku, obstétricien-gynécologue et l'un des chercheurs en santé maternelle les plus dévoués de Tanzanie, est décédé en septembre 2018. Sa carrière professionnelle a duré plus de quatre décennies, la dernière décennie de sa vie étant consacrée à la recherche, au plaidoyer et aux politiques en santé maternelle en Afrique. Nous avons entrepris un examen des principales étapes mondiales de la politique, du financement et de la recherche en matière de santé maternelle qui ont eu lieu au cours de la carrière du Dr Mbaruku jusqu'à sa mort prématurée en 2018. Nous réfléchissons ensuite aux progrès du programme de santé maternelle de 2018 à 2021 en tant que milieu inférieur. Les pays à revenu intermédiaire (PRFI) continuent de s'efforcer d'atteindre les objectifs de développement durable (ODD) au milieu d'une pandémie mondiale. L'engagement du Dr Godfrey Mbaruku à améliorer la santé maternelle en Tanzanie grâce à ses contributions de plaidoyer et de recherche au cours de sa vie professionnelle servira à jamais de piliers fondamentaux pour l'effort mondial en cours pour réduire la mortalité maternelle

Bringing together emerging and endemic zoonoses surveillance: shared challenges and a common solution

Early detection of disease outbreaks in human and animal populations is crucial to the effective surveillance of emerging infectious diseases. However, there are marked geographical disparities in capacity for early detection of outbreaks, which limit the effectiveness of global surveillance strategies. Linking surveillance approaches for emerging and neglected endemic zoonoses, with a renewed focus on existing disease problems in developing countries, has the potential to overcome several limitations and to achieve additional health benefits. Poor reporting is a major constraint to the surveillance of both emerging and endemic zoonoses, and several important barriers to reporting can be identified: (i) a lack of tangible benefits when reports are made; (ii) a lack of capacity to enforce regulations; (iii) poor communication among communities, institutions and sectors; and (iv) complexities of the international regulatory environment. Redirecting surveillance efforts to focus on endemic zoonoses in developing countries offers a pragmatic approach that overcomes some of these barriers and provides support in regions where surveillance capacity is currently weakest. In addition, this approach addresses immediate health and development problems, and provides an equitable and sustainable mechanism for building the culture of surveillance and the core capacities that are needed for all zoonotic pathogens, including emerging disease threats

The epidemiology of residual Plasmodium falciparum malaria transmission and infection burden in an African city with high coverage of multiple vector control measures.

BACKGROUND In the Tanzanian city of Dar es Salaam, high coverage of long-lasting insecticidal nets (LLINs), larvicide application (LA) and mosquito-proofed housing, was complemented with improved access to artemisinin-based combination therapy and rapid diagnostic tests by the end of 2012. METHODS Three rounds of city-wide, cluster-sampled cross-sectional surveys of malaria parasite infection status, spanning 2010 to 2012, were complemented by two series of high-resolution, longitudinal surveys of vector density. RESULTS Larvicide application using a granule formulation of Bacillus thuringiensis var. israelensis (Bti) had no effect upon either vector density (P = 0.820) or infection prevalence (P = 0.325) when managed by a private-sector contractor. Infection prevalence rebounded back to 13.8 % in 2010, compared with <2 % at the end of a previous Bti LA evaluation in 2008. Following transition to management by the Ministry of Health and Social Welfare (MoHSW), LA consistently reduced vector densities, first using the same Bti granule in early 2011 [odds ratio (OR) (95 % confidence interval (CI)) = 0.31 (0.14, 0.71), P = 0.0053] and then a pre-diluted aqueous suspension formulation from mid 2011 onwards [OR (95 % CI) = 0.15 (0.07, 0.30), P ≪ 0.000001]. While LA by MoHSW with the granule formulation was associated with reduced infection prevalence [OR (95 % CI) = 0.26 (0.12, 0.56), P = 0.00040], subsequent liquid suspension use, following a mass distribution to achieve universal coverage of LLINs that reduced vector density [OR (95 % CI) = 0.72 (0.51, 1.01), P = 0.057] and prevalence [OR (95 % CI) = 0.80 (0.69, 0.91), P = 0.0013], was not associated with further prevalence reduction (P = 0.836). Sleeping inside houses with complete window screens only reduced infection risk [OR (95 % CI) = 0.71 (0.62, 0.82), P = 0.0000036] if the evenings and mornings were also spent indoors. Furthermore, infection risk was only associated with local vector density [OR (95 % CI) = 6.99 (1.12, 43.7) at one vector mosquito per trap per night, P = 0.037] among the minority (14 %) of households lacking screening. Despite attenuation of malaria transmission and immunity, 88 % of infected residents experienced no recent fever, only 0.4 % of these afebrile cases had been treated for malaria, and prevalence remained high (9.9 %) at the end of the study. CONCLUSIONS While existing vector control interventions have dramatically attenuated malaria transmission in Dar es Salaam, further scale-up and additional measures to protect against mosquito bites outdoors are desirable. Accelerated elimination of chronic human infections persisting at high prevalence will require active, population-wide campaigns with curative drugs

The need to improve access to rabies post-exposure vaccines: Lessons from Tanzania

Background Rabies is preventable through prompt administration of post-exposure prophylaxis (PEP) to exposed persons, but PEP access is limited in many rabies-endemic countries. We investigated how access to PEP can be improved to better prevent human rabies. Methods Using data from different settings in Tanzania, including contact tracing (2,367 probable rabies exposures identified) and large-scale mobile phone-based surveillance (24,999 patient records), we estimated the incidence of rabies exposures and bite-injuries, and examined health seeking and health outcomes in relation to PEP access. We used surveys and qualitative interviews with stakeholders within the health system to further characterise PEP supply and triangulate these findings. Results Incidence of bite-injury patients was related to dog population sizes, with higher incidence in districts with lower human:dog ratios and urban centres. A substantial percentage (25%) of probable rabies exposures did not seek care due to costs and limited appreciation of risk. Upon seeking care a further 15% of probable rabies exposed persons did not obtain PEP due to shortages, cost barriers or misadvice. Of those that initiated PEP, 46% did not complete the course. If no PEP was administered, the risk of developing rabies following a probable rabies exposure was high (0.165), with bites to the head carrying most risk. Decentralized and free PEP increased the probability that patients received PEP and reduced delays in initiating PEP. No major difficulties were encountered by health workers whilst switching to dose-sparing ID administration of PEP. Health infrastructure also includes sufficient cold chain capacity to support improved PEP provision. However, high costs to governments and patients currently limits the supply chain and PEP access. The cost barrier was exacerbated by decentralization of budgets, with priority given to purchase of cheaper medicines for other conditions. Reactive procurement resulted in limited and unresponsive PEP supply, increasing costs and risks to bite victims. Conclusion PEP access could be improved and rabies deaths reduced through ring-fenced procurement, switching to dose-sparing ID regimens and free provision of PEP

An affordable, quality-assured community-based system for high-resolution entomological surveillance of vector mosquitoes that reflects human malaria infection risk patterns.

ABSTRACT: BACKGROUND: More sensitive and scalable entomological surveillance tools are required to monitor low levels of transmission that are increasingly common across the tropics, particularly where vector control has been successful. A large-scale larviciding programme in urban Dar es Salaam, Tanzania is supported by a community-based (CB) system for trapping adult mosquito densities to monitor programme performance. Methodology An intensive and extensive CB system for routine, longitudinal, programmatic surveillance of malaria vectors and other mosquitoes using the Ifakara Tent Trap (ITT-C) was developed in Urban Dar es Salaam, Tanzania, and validated by comparison with quality assurance (QA) surveys using either ITT-C or human landing catches (HLC), as well as a cross-sectional survey of malaria parasite prevalence in the same housing compounds. RESULTS: Community-based ITT-C had much lower sensitivity per person-night of sampling than HLC (Relative Rate (RR) [95% Confidence Interval (CI)] = 0.079 [0.051, 0.121], P < 0.001 for Anopheles gambiae s.l. and 0.153 [0.137, 0.171], P < 0.001 for Culicines) but only moderately differed from QA surveys with the same trap (0.536 [0.406,0.617], P = 0.001 and 0.747 [0.677,0.824], P < 0.001, for An. gambiae or Culex respectively). Despite the poor sensitivity of the ITT per night of sampling, when CB-ITT was compared with QA-HLC, it proved at least comparably sensitive in absolute terms (171 versus 169 primary vectors caught) and cost-effective (153US$versus 187US$ per An. gambiae caught) because it allowed more spatially extensive and temporally intensive sampling (4284 versus 335 trap nights distributed over 615 versus 240 locations with a mean number of samples per year of 143 versus 141). Despite the very low vectors densities (Annual estimate of about 170 An gambiae s.l bites per person per year), CB-ITT was the only entomological predictor of parasite infection risk (Odds Ratio [95% CI] = 4.43[3.027,7. 454] per An. gambiae or Anopheles funestus caught per night, P =0.0373). Discussion and conclusion CB trapping approaches could be improved with more sensitive traps, but already offer a practical, safe and affordable system for routine programmatic mosquito surveillance and clusters could be distributed across entire countries by adapting the sample submission and quality assurance procedures accordingly