This blog is the fourth in a seven-part series examining the nature and reasons for the near elimination of malaria in Zanzibar since 2000. This question forms the basis of a major new research project and big conversation about malaria led by the Zanzibar Research Centre for Socio-Economic and Policy Analysis (ZRCP). A link to the full report from ZRCP can be found here. This blog follows from Part Three: Does Healthier make you Wealthier? The Economic Benefits of (Near) Malaria Elimination in Zanzibar

Malaria in Zanzibar: a recap

Malaria is spread to humans through mosquito bites, with symptoms ranging from mild (fever, chills and a headache), to more severe (coma, severe anaemia, seizures, and difficulty breathing), and in too many cases death. Infants, children under 5 years, and pregnant women are at higher risk of severe infection. 

In the early 2000s, the World Health Organization (WHO) estimated there were between 300 and 500 million global cases of malaria a year, resulting in between 700,000 and 2.7 million deaths annually. During that time, 90% of the malaria disease burden was located in Africa. 

New evidence on the economic and human cost of malaria in the 1990s helped inspire a renewed global elimination effort. A big push backed by global leaders, funders, and researchers and in Africa governments, health care professionals, volunteers, statisticians, and households was launched in the early 2000s, leading to a dramatic global reduction in the incidence of malaria, and after 2012, the successful trial and later in 2022 the scaling up of a malaria vaccine. After 2015 the WHO verified the complete elimination of malaria in a succession of countries.

Across Africa after 2000, the most successful countries were those that reduced the incidence of and mortality from malaria by 50%. Zanzibar went much further, to near elimination.

Eliminate Malaria in Zanzibar: An Obvious Policy Goal?

Is there any point in reading further? Across three blogs in this series we have repeated the point that Zanzibar (after 5,000 years) has nearly eliminated malaria. Is there any real point in debating whether Zanzibar should make that final push to eliminate the last 5% of a grisly 5,000 year-old scourge?

Much of the global malaria community is indeed focused on the goal of elimination.

Of the 93 countries that were malaria endemic in 2015, eight countries have been certified by the WHO as malaria free since 2015: Algeria, Azerbaijan, Belize, Cabo Verde, China, El Salvador, Sri Lanka and Tajikistan.

In 2020 the global Roll Back Malaria (RBM) campaign launched new global targets, by 2025 to reduce the incidence and mortality rates of malaria by at least 75 per cent compared with 2015; to prevent the re-emergence of malaria in countries that were malaria-free in 2015; and to eliminate malaria in a further 20 countries compared to 2015. By 2030 RBM target the reduction of malaria incidence and mortality rates by at least 90 per cent compared with 2015 levels; eliminate malaria in a further 35 countries compared to 2015; and to prevent the re-emergence of malaria in all malaria-free countries. 

Putting aside the comforting rhetoric of ‘elimination’ the definition of ‘elimination’ means that it is actually a very demanding public health goal. WHO certification is awarded when a country or territory can prove that the mosquito-borne transmission chain has been interrupted nationwide resulting in zero indigenous malaria cases for at least 3 consecutive years. The country is also required to have a programme in place for preventing the re-establishment of transmission. Should Zanzibar focus on the very demanding requirements for elimination or focus on the less demanding challenge of eradicating deaths from malaria? 

While 8 countries have eliminated malaria since 2015 there are 30 countries that were malaria endemic in 2015 that were reporting zero malaria deaths in 2023. Should this be the (less demanding) goal for Zanzibar? Such a goal would require a policy focus on targeting anti-malaria interventions towards high risk and vulnerable populations and a switch away from malaria case management towards malaria surveillance and response.

Multiple Policy Paths Towards a Malaria Goal in Zanzibar

Even once Zanzibar has established a goal there needs to be careful thinking about the best means to achieve that goal.

Should Zanzibar continue to disseminate traditional anti-malaria technologies whose usage has already reached very high levels? By 2023, 73% of households in sub-Saharan Africa had at least one ITN, increasing from about 5% in 2000. The percentage of children under 5 years sleeping under an ITN increased from 2% in 2000 to 52% 2023. In 2023 Tanzania received delivery of almost 19 million bed-nets. Globally, 4.4 billion rapid diagnostic tests (RDTs) for malaria were sold by manufacturers between 2010 and 2023, with more than 82% of sales in sub-Saharan African countries. 

Each technology needs to be carefully evaluated for its efficacy in the Zanzibari context. When malaria was endemic a typical policy response is that of reactive case detection (RCD). Once an individual has tested positive a public health team conduct a follow up based on the assumption that other detectable malaria infections will be located within and around that individuals household. The RCD approach has guided testing and treatment efforts in Zanzibar to good effect over the last two decades. This method is less effective today in Zanzibar. Data collected by Zanzibar’s Malaria Case Notification (MCN) system shows that more than 40% of cases had a travel history outside Zanzibar in the month prior to testing positive for malaria. One study used mobile phone usage data and ferry traffic between Zanzibar and mainland Tanzania and found that local transmission was too low to sustain transmission in most places. This was confirmed by another study which showed that in the absence of imported cases from mainland Tanzania, malaria would likely cease to persist on Zanzibar. Malaria infections in Zanzibar largely result from imported malaria and subsequent transmission. Improving control requires quantifying malaria importation rates, identifying high-risk travellers, and assessing onwards transmission. Despite being certified malaria free in 2012, between 2013 and 2023 a survey identified 532 cases of imported malaria into Sri Lanka, mostly Sri Lankan nationals returning from Africa. 

Should Zanzibar adopt the new anti-malarial technologies that are becoming available? Since 2019, Ghana, Kenya and Malawi have been delivering malaria vaccines, through their respective routine child immunization programmes to children from 5 months of age. Between 2019 and 2023, more than 6 million vaccine doses were delivered, reaching about 2 million children. In December 2023, WHO added a second malaria vaccine ‘R21’ to its list of prequalified vaccines. A new insecticide treated net (ITN) with dual active ingredients was trialled between 2019 and 2022. The trials found the new ITN improved malaria control by 20–50% compared with standard pyrethroid-only nets. In 2023 20% (nearly 40 million) of the near 200 million bed-nets delivered to SSA were dual active ingredient ITNs. During 2023 seasonal malaria chemoprevention (SMC) was being implemented across sub-Saharan Africa to 53 million children.

Zanzibar needs to ask what finance is available to support any of these traditional or new technologies. There does exist donor support. Total funding for malaria in 2023 was estimated at US$ 4.0 billion, showing a slight decrease from US$ 4.1 billion in 2022. However, this represents an increase from US$ 3.5 billion in 2021 and US$ 3.3 billion in 2020. In 2024 Ghana, Kenya, and Malawi were offering the new malaria vaccine with support from Gavi, the Vaccine Alliance (Gavi), the WHO and other partners. 

A Joint External Evaluation (JEE) in Zanzibar led by the WHO found that 

“Zanzibar has access to financial resources for the routine implementation of IHR capacities, and financial resources are available that can be accessed on time and distributed for readiness and response to public health emergencies” (p11). 

Zanzibar has also made significant efforts to mobilise domestic sources, as noted by the JEE, “In order to have a sustainable supply of vaccines, the United Republic of Tanzania–Zanzibar has been progressively increasing the annual budget quota for procurement of Gavi co-financing of vaccines from US$ 534,782 in the 2020–2021 financial year to US$ 782,608 in 2022–2023. Government funds are available for procurement of vaccines through ring-fenced funds at the Ministry of Finance.” (p28-30). 

The structural infrastructure is likewise in place to ramp up coverage of a malaria vaccine in Zanzibar. The central vaccine store is currently equipped with walk-in-cold rooms and freezers. The Government of Zanzibar, with the support of Gavi co-financing, has procured solar direct drive refrigerators as a backup system at district levels. All district vaccine stores are currently equipped with electric refrigerators. Availability of partners in immunization plays an enormous role in improving access to quality immunization services at all levels.” (p28-30). 

Also the JEE found, “Systems are also in place to reach marginalized populations using the Reach Every Child strategy and vaccine delivery has been tested through a nationwide measles mass vaccination campaign.” (p28-30). Despite this domestic and international effort there are concerns that the cost of new malaria technology is running ahead of the capacity of Zanzibar and other countries to raise the funds to utilize it. While global support exists it is no longer enough. The Strategic Plan for 2021-2025 from the RBM explains, 

“Funding for the global malaria response has plateaued since 2010, falling at least US$2.6 billion short per year of the total amount necessary to provide all those at risk with the life-saving malaria tools they need. At the same time, new challenges – including emerging drug and insecticide resistance, increasing population movement, and rising cases in the highest burden countries – mean we must invest even more in researching, developing and scaling up essential tools”. 

Despite the 2023 investment reaching US$ 4.0 billion, this falls short of the estimated US$ 8.3 billion needed globally to meet the GTS targets by 2023. The funding gap has widened over the past 5 years, increasing from US$ 2.6 billion in 2019 to US$ 4.3 billion in 2023, meaning that only 48% of the required funding. The health budget in Zanzibar increased from $31.7 million in 2017-18 to $117.3 million in 2022-23, but that portion specifically allocated to malaria remained less than 1% of the total. 

Some Difficult Questions for Zanzibar

Zanzibar needs to ask some difficult questions. 

What is the goal for Zanzibar, to eliminate malaria, to prevent a resurgence from existing low levels, or to eliminate deaths from malaria?

What are the costs of an anti-malaria strategy into the future, thinking carefully here about the costs of traditional and new technologies relative to the resources available to finance them?

What are the economic benefits of an anti-malaria strategy that have already been achieved (see blog 3 in this series) from having (nearly) eliminated malaria and what extra gains would there be from complete elimination? 

These questions are complicated by the fact that they must be asked in Zanzibar in an environment of low malaria where there exists a real risk of a resurgence of malaria (see Blog 6). As one study put it,

“It is a mistake to judge the return on malaria investments in relation to the current burden of malaria. A facile weighting of the millions invested in malaria interventions against a few remaining cases produces the erroneous conclusion that those funds are achieving little. The true value of these investments is the number of deaths and cases that are prevented, not that remain.” 

Look out for Part Five: It is Like a Horror Film, the Villain Keeps Coming Back to Life: The Risks of a Malaria Revival in Zanzibar