Evidence quality 4.88/5
Eight-dimension review score against the quality rubric . Each dimension scored 1–5.
- D1 Source grounding
- 5/5
- D2 Source authority
- 5/5
- D3 Arithmetic
- 5/5
- D4 Uncertainty
- 5/5
- D5 Scope
- 5/5
- D6 Prose
- 5/5
- D7 Perception honesty
- 4/5
- D8 Caveat completeness
- 5/5
≈ As likely as
Perceived
In wealthy countries, freshwater swimming is a leisure activity associated with sunburn and the occasional ear infection, not parasitic disease. The word schistosomiasis itself is unfamiliar to most people outside tropical medicine. Yet the disease, caused by parasitic flatworms released by freshwater snails, infects more than 250 million people globally and kills an estimated 14,353 per year globally (WHO; likely an underestimate). Chronic infection causes liver fibrosis, bladder cancer, kidney failure, and anaemia. Because it is a disease of poverty concentrated in tropical Africa, it receives minimal media attention in the countries that produce most global health coverage. Note: infection probability is orders of magnitude higher than death probability — over 250 million are currently infected. This entry measures the probability of dying from schistosomiasis.
Source: editorial intuition, not polled
Actual
~12,858 deaths per year globally (GBD 2021 direct coding); 250+ million infected
global adults and children
Show derivation
Native rate: The GBD 2021 study recorded 12,858 deaths coded directly to schistosomiasis globally. This is the only methodologically rigorous global mortality figure available. The WHO now estimates 14,353 deaths globally per year, noting these figures are likely underestimated because deaths from schistosomiasis-driven organ damage (liver fibrosis, bladder cancer, renal failure) are coded to the proximate cause rather than the parasitic infection. Using the GBD global figure: 12,858 / 5,000,000,000 = 0.00000257 annual rate. Lifetime conversion: 1 - (1 - 0.00000257)^59 = 0.00015. Uncertainty reflects plausible undercounting of indirect deaths at the global level: the GBD figure captures only directly coded deaths, so true global mortality including indirect pathways may be 2-4x higher. Low bound uses a conservative GBD estimate of ~10,000/5B compounded 59 years = 0.00012. High bound assumes indirect mortality triples the directly coded figure to ~40,000 globally: 40,000/5B compounded 59 years = 0.00047. For anyone not exposed to endemic freshwater in tropical Africa or parts of Asia and South America, personal probability is effectively zero.
Caveats: The central estimate uses the GBD 2021 figure of 12,858 directly coded global de…
The central estimate uses the GBD 2021 figure of 12,858 directly coded global deaths per year. This likely undercounts true attributable mortality because chronic schistosomiasis causes liver fibrosis, portal hypertension, bladder cancer, and renal failure, and deaths from these conditions are typically coded to the end-organ diagnosis rather than the parasitic infection. The WHO now estimates 14,353 deaths globally per year but notes these figures are likely underestimated. The uncertainty high bound assumes indirect deaths may triple the directly coded global figure. The risk is geographically extreme: for anyone not regularly exposed to freshwater in endemic areas of sub-Saharan Africa, parts of South America, or Southeast Asia, personal probability is effectively zero. Travellers who avoid freshwater contact in endemic regions are not at risk.
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Pick challenger
Schistosomiasis is a parasitic disease caused by blood flukes of the genus Schistosoma, transmitted through freshwater snails in tropical and subtropical regions. While over 250 million people are infected globally — making infection probability very high in endemic areas — this entry focuses on the probability of dying from the disease. The GBD 2021 study recorded 12,858 deaths coded directly to schistosomiasis worldwide, while at least 253.7 million people required preventive treatment in 2024. The parasites penetrate intact skin during freshwater contact, mature in the blood vessels, and deposit eggs that lodge in the liver, intestines, or bladder, triggering chronic inflammation that over years can progress to liver fibrosis, portal hypertension, bladder cancer, and kidney failure. The WHO now estimates 14,353 deaths globally per year, though it notes these figures are likely underestimated because deaths from schistosomiasis-driven organ damage are often coded to the proximate cause.
The perception gap is almost total outside the endemic zone. In wealthy countries, schistosomiasis is a travel-medicine footnote, something a doctor might mention before a trip to Lake Malawi. The disease does not appear in popular risk rankings, is rarely covered in general media, and its name is difficult enough to pronounce that it resists casual conversation. Meanwhile it ranks among the most prevalent parasitic diseases on Earth, second only to malaria in terms of socioeconomic impact in sub-Saharan Africa. Roughly 90% of the global burden is concentrated in Africa, where children who swim or wade in rivers and lakes as part of daily life are the primary victims. Mass drug administration with praziquantel is cheap and effective but coverage remains incomplete: only 100.5 million of the 253.7 million people needing treatment were reached in 2024.
Where the number does not apply: any person who does not have regular freshwater exposure in an endemic region of sub-Saharan Africa, parts of South America, or Southeast Asia has effectively zero personal risk of death from schistosomiasis. The 1-in-6,580 lifetime figure is a global average for death, pulled almost entirely by rural populations in tropical Africa. Infection probability is a separate and much higher figure — with 250+ million currently infected out of roughly 800 million at risk, the infection rate in endemic populations is very high. Even within endemic countries, both infection and death risk are highly localised, concentrated around specific water bodies harbouring the intermediate snail hosts. Travellers to endemic areas can reduce risk to near zero by avoiding freshwater contact. The uncertainty interval (1-in-8,333 to 1-in-2,128) reflects plausible undercounting of indirect deaths at the global level.
Related tidbits
Schistosomiasis carries a global lifetime fatality risk near 1 in 6,580, with about 12,858 directly coded deaths a year. More than 250 million people are infected, mostly in sub-Saharan Africa.
Claim ledger
Every number below is what each source reported, with the verbatim quote we relied on and how we arrived at our figure. Click any link to verify directly.
2/3 sources independently verified verbatim against the cited source
-
[1] World Health Organization — Schistosomiasis — Fact sheet Verified
Schistosomiasis — Fact sheet- Statistic
At least 253.7 million people required preventive treatment in 2024; deaths estimated at 14,353 globally per year- Excerpt
“"Estimates show that at least 253.7 million people required preventive treatment for schistosomiasis in 2024. Deaths due to schistosomiasis are currently estimated at 14 353 globally per year. However, these figures are likely underestimated and need to be reassessed." ”
- Source data from
- 2026-02-01
- Accessed
- 2026-04-24 · archived copy
- Verification
- Excerpt independently re-fetched and confirmed word-for-word against the cited source during our grounding audit.
- Calculation
- The WHO now estimates 14,353 deaths globally per year from schistosomiasis, noting these figures are likely underestimated. This is consistent with the GBD 2021 figure of 12,858 directly coded deaths used as the primary numerator. 12,858 / 5B = 0.00000257 annual rate, compounded over 59 years yields 0.00015. The WHO acknowledges underestimation because deaths from schistosomiasis-driven organ damage (liver fibrosis, bladder cancer, renal failure) are often coded to the proximate cause.
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[2] PMC / Wien Med Wochenschr — Schistosomiasis with a Focus on Africa Verified
Schistosomiasis with a Focus on Africa- Statistic
Sub-Saharan Africa accounts for up to 90% of cases globally with an estimated 280,000 deaths due to schistosomiasis annually; 800 million people at risk- Excerpt
“"Sub-Saharan Africa (SSA) constitutes about 13% of the world's population but accounts for up to 90% of cases with an estimated 280,000 deaths due to schistosomiasis annually. The disease still prevails in most parts of sub-Saharan Africa with an estimated 800 million people at risk of infection." ”
- Source data from
- 2021-07-01
- Accessed
- 2026-04-24 · archived copy
- Verification
- Excerpt independently re-fetched and confirmed word-for-word against the cited source during our grounding audit.
- Calculation
- This peer-reviewed source provides an independent estimate of 280,000 annual deaths concentrated in sub-Saharan Africa (90% of cases). Like the WHO figure, this is a regional estimate including indirect mortality and cannot be divided by global population. It confirms the extreme geographic concentration of the burden and the large gap between directly coded deaths (GBD: 12,858) and attributable mortality estimates that include indirect organ-damage pathways.
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[3] Parasite (EDP Sciences) — The impact of schistosomiasis on the Global Disease Burden: a systematic analysis based on the 2021 Global Burden of Disease study
The impact of schistosomiasis on the Global Disease Burden: a systematic analysis based on the 2021 Global Burden of Disease study- Statistic
Globally, schistosomiasis resulted in 12,857.57 deaths in 2021; Africa accounted for 87.28% of the global mortality burden- Excerpt
“"Globally, schistosomiasis resulted in 12,857.57 deaths in 2021. Africa accounted for 87.28% of the global mortality burden. The global prevalence of schistosomiasis was 151.38 million cases and caused 1,746,333.31 DALYs in 2021." ”
- Source data from
- 2025-02-01
- Accessed
- 2026-04-24 · archived copy
- Calculation
- The GBD 2021 figure of 12,858 globally coded deaths is the primary numerator for the native rate. This is the only rigorous global mortality estimate available. It likely undercounts true attributable mortality because deaths from schistosomiasis-driven organ damage (liver fibrosis, bladder cancer, renal failure) are coded to the proximate cause rather than the parasitic infection. The uncertainty high bound assumes indirect mortality may triple the directly coded figure to ~40,000 globally. 12,858 / 5B compounded 59 years = 0.00015 (central estimate).