>> Writes Kennedy Lushasi, Sarah Hayes, Ahmed Lugelo, Felix Lankester, Christl Donnelly and Katie Hampson

In March 2024, Maria, a 60-year-old woman from Tanzania’s southeastern Lindi Region, was bitten by her own dog. A month earlier, the dog had been bitten by a jackal while they were on the farm. The jackal disappeared, but weeks later the dog began behaving strangely and bit Maria. Though she was treated with traditional medicine and initially appeared to recover, weeks later, symptoms developed, including fever, difficulty drinking and eating, and excessive salivation. Her family eventually sought help from local authorities, but she died before she reached hospital.

Maria’s story illustrates why rabies control is not simply about treating individual bites. It is about understanding where infection comes from, how it moves between animals and people, and which populations sustain transmission.

Rabies is the world’s deadliest disease with no cure once symptoms start. It claims tens of thousands of lives each year, most of whom are children (Hampson et al., 2015; World Health Organization, 2018a).

These deaths are especially tragic because rabies is preventable. Prompt post-exposure prophylaxis (PEP) can prevent rabies after an exposure like Maria’s. Yet access to PEP remains a major challenge. In Liwale District, five people were bitten by an unvaccinated dog. Although all sought care, one family member received only one vaccine dose. As the village chairperson explained: “He received only one dose. He could not continue because the cost of treatment and transport was too high. About a month later, the man developed symptoms and died”.

But preventing human deaths also requires understanding where the virus comes from. In some parts of Tanzania, rabies is frequently detected in wildlife. Does this mean wildlife populations maintain transmission, or are these infections the result of spillover from domestic dogs? Resolving this question is critical for identifying where control efforts should be targeted and whether dog vaccination alone can interrupt transmission.

Rabies as a One Health challenge

One Health recognises that human, animal, and ecosystem health are interconnected. Rabies makes these connections especially clear: it is a multi-host zoonotic pathogen capable of infecting any mammal; its transmission is shaped by interactions among people, domestic animals and wildlife, and its control requires coordinated action across sectors.

Mass dog vaccination has eliminated dog-mediated human rabies in Europe, North America, parts of Asia and much of Latin America. Rabies nevertheless remains endemic across large parts of Africa and Asia, disproportionately affecting poor and marginalised communities. Africa has the world’s highest estimated per-capita human rabies mortality rate, at 2.09 deaths per 100,000 people (Hampson et al., 2015; Taylor and Nel, 2015).

Preventing rabies in domestic animals can bring wide-reaching benefits. Controlling infection in dogs protects the dogs themselves while reducing onward transmission to people, livestock and wildlife, like the jackal that sadly led to Maria’s death. It can also support conservation: previous rabies outbreaks have caused devastating losses among endangered Ethiopian wolves and African wild dogs (Sillero-Zubiri et al., 1996; Kat et al., 1997; Randall et al., 2006; Johnson et al., 2010).

The Tanzania case study, Understanding Reservoirs of Multi-Host Pathogens: A One Health Approach to Rabies in Tanzania, published in CABI's One Health Cases in January 2025, illustrates these benefits through examples from two contrasting settings: the southern regions of Lindi (Maria’s home region) and Mtwara, where wildlife comprise a relatively large proportion of reported animal cases, and the island of Pemba, where cases predominantly occur in domestic dogs. Examining these different settings helps demonstrate why understanding local disease ecology is essential and why interventions directed at domestic dogs can remain effective even where wildlife infections occur.

One Health is not simply a description of how diseases move among species. It is a practical model for collaboration. Cooperation between human healthcare and veterinary services can strengthen surveillance, improve evaluation of control programmes and provide a clearer understanding of risk. Information collected from people attending health facilities with bite injuries can prompt investigations of the animals involved, while veterinary findings can inform risk assessments and decisions about human treatment.

Crucially, this collaboration helps identify the populations that maintain the virus. Evidence from Tanzania indicates that domestic dogs are the essential maintenance population, although wildlife can become infected and contribute to onward transmission. Targeting vaccination at the maintenance host increases the likelihood of interrupting transmission across the wider system.

This preventative approach is also an issue of equity. Although PEP can stop rabies from developing after exposure, access is often limited by cost, availability and distance from healthcare facilities (Lushasi et al., 2026). These barriers fall most heavily on poor and marginalised communities as described by the village chairman from Liwale district. Reducing rabies at its animal source prevents human exposures and decreases reliance on emergency treatment that many people struggle to obtain.

These principles support the global “Zero by 30” goal of ending human deaths from dog-mediated rabies by 2030 (World Health Organization, 2018b). Achieving that goal will require sustained dog vaccination, accessible PEP, effective surveillance and long-term cooperation among veterinary, public-health, wildlife, research, and community partners.

Which species maintain rabies transmission?

An important question for disease-control programmes is whether dog vaccination is sufficient in areas where many rabies cases occur in wildlife?

Answering this question requires distinguishing between a maintenance host and a species infected through spillover. A maintenance-host population can sustain pathogen transmission over time, whereas a non-maintenance population may experience infections and contribute to short-term transmission but cannot sustain the pathogen without repeated introductions (Haydon et al., 2002). If one species maintains a pathogen, targeting that species can ultimately eliminate infection from other susceptible populations.

Identifying maintenance hosts, however, is rarely straightforward. In Tanzania’s Serengeti ecosystem, researchers combined several types of evidence to show that domestic dogs were the only population essential to rabies maintenance, even though other carnivores contributed to transmission (Lembo et al., 2008).

Lessons from southern Tanzania and Pemba

The Tanzania case study examines rabies control in areas with contrasting disease ecologies. In the southern regions of Lindi and Mtwara, wildlife, particularly jackals, account for an unusually high proportion of reported animal cases. On the island of Pemba, cases have been dominated by domestic dogs. This contrast provided an opportunity to examine whether dog vaccination could reduce rabies transmission even where wildlife infections were common.

Dog vaccination reduced rabies despite wildlife infections

A government-led project began in 2010 across several southern Tanzanian regions and Pemba, combining mass dog vaccination, free PEP, improved diagnostics, and strengthened surveillance (Mpolya et al., 2017; Sambo et al., 2022). Five rounds of dog vaccination were conducted between 2010 and February 2017, after which animal rabies cases, human exposures, and human deaths declined in all settings.

On Pemba, rabies was eliminated by May 2014, with no detected human exposures, deaths or animal cases until July 2016. When rabies reappeared, phylogenetic analysis showed that it had been reintroduced through imported dogs (likely brought by boat) rather than persisting through undetected transmission locally (Lushasi et al., 2023). This highlighted the importance of maintaining dog vaccination to prevent reintroduction and resurgence.

The findings from Lindi and Mtwara were particularly important because wildlife accounted for such a high proportion of reported animal cases (>30%!). Despite this, dog vaccination substantially reduced rabies across all species (Lushasi et al., 2021). The evidence indicated that dogs were the essential maintenance population, while wildlife infections were primarily the result of spillover. When dog vaccination stopped, human and animal rabies cases increased again, returning towards levels observed at the start of the project.

Conclusion

Tanzania’s experience shows why a One Health approach is essential for rabies elimination. Linking human and animal surveillance, understanding where transmission is maintained, and sustaining vaccination can help move rabies control beyond responding to individual bites towards interrupting transmission at its source. The experience from southern Tanzania and Pemba shows that targeting domestic dogs can protect people and animals even where rabies is also detected in wildlife.

Key messages

Wildlife infections do not necessarily mean that wildlife is maintaining rabies transmission. In southern Tanzania, the evidence showed that domestic dogs remained the critical population to target, even where wildlife cases were common.

The reduction and elimination of rabies from repeated dog vaccination campaigns, was followed by resurgence after vaccination stopped, demonstrating the importance of maintaining vaccination campaigns over time.

Contact tracing and investigation of biting animals linked human exposures with animal infections, providing evidence to understand transmission, evaluate vaccination and clarify the respective roles of dogs and wildlife.

The blog was first published on 21 September 2026 on the CABI Digital Library

_______________

Kennedy Lushasi is a Researcher at the Ifakara Health Institute and leads the SOS-Rabies project, contributing to research and implementation efforts aimed at strengthening rabies elimination across Tanzania and Africa.