{
  "slug": "schistosomiasis",
  "question": "What are the odds of dying from schistosomiasis?",
  "category": "health",
  "tags": [
    "travel"
  ],
  "no_reliable_estimate": false,
  "perceived": {
    "description": "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.\n",
    "kind": "intuition"
  },
  "native": {
    "display": "~12,858 deaths per year globally (GBD 2021 direct coding); 250+ million infected",
    "numerator": 12858,
    "denominator": 5000000000,
    "unit": "per year",
    "population": "global adults and children"
  },
  "normalized": {
    "lifetime_us_adult": 0.00015,
    "display": "~1 in 6,580 lifetime (global adult)",
    "log_value": -3.82,
    "assumptions": "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.\n",
    "uncertainty": {
      "low": 0.00012,
      "high": 0.00047
    },
    "scope": "global_adult_lifetime"
  },
  "sources": [
    {
      "url": "https://www.who.int/news-room/fact-sheets/detail/schistosomiasis",
      "title": "Schistosomiasis — Fact sheet",
      "publisher": "World Health Organization",
      "source_type": "govt_report",
      "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.\"\n",
      "source_date": "2026-02-01",
      "source_accessed": "2026-04-24",
      "archive_url": "http://web.archive.org/web/20260404102503/https://www.who.int/news-room/fact-sheets/detail/schistosomiasis",
      "calculation_notes": "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.\n"
    },
    {
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC8293433/",
      "title": "Schistosomiasis with a Focus on Africa",
      "publisher": "PMC / Wien Med Wochenschr",
      "source_type": "peer_reviewed",
      "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.\"\n",
      "source_date": "2021-07-01",
      "source_accessed": "2026-04-24",
      "archive_url": "https://web.archive.org/web/20260426210605/https://pmc.ncbi.nlm.nih.gov/articles/PMC8293433/",
      "calculation_notes": "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.\n"
    },
    {
      "url": "https://www.parasite-journal.org/articles/parasite/full_html/2025/01/parasite240186/parasite240186.html",
      "title": "The impact of schistosomiasis on the Global Disease Burden: a systematic analysis based on the 2021 Global Burden of Disease study",
      "publisher": "Parasite (EDP Sciences)",
      "source_type": "peer_reviewed",
      "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.\"\n",
      "source_date": "2025-02-01",
      "source_accessed": "2026-04-24",
      "archive_url": "http://web.archive.org/web/20260201091110/https://www.parasite-journal.org/articles/parasite/full_html/2025/01/parasite240186/parasite240186.html",
      "calculation_notes": "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).\n"
    }
  ],
  "comparison_anchors": [
    {
      "label": "Death from rabies via dog bite (lifetime, global adult)",
      "lifetime_us_adult": 0.00069
    },
    {
      "label": "Death from typhoid fever (lifetime, global adult)",
      "lifetime_us_adult": 0.00153
    },
    {
      "label": "Death from malaria (lifetime, global adult)",
      "lifetime_us_adult": 0.0086
    }
  ],
  "short_label": "Schistosomiasis death",
  "myth_framing": "underrated",
  "outcome_severity": "fatal",
  "exposure_pattern": "cumulative",
  "outcome_type": "death",
  "valence": "negative",
  "caveats": "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.\n",
  "quality_score": {
    "d1": 5,
    "d2": 5,
    "d3": 5,
    "d4": 5,
    "d5": 5,
    "d6": 5,
    "d7": 4,
    "d8": 5,
    "avg": 4.875,
    "scored_by": "extracted-from-transcript",
    "scored_at": "2026-05-16",
    "methodology_version": "1.0"
  },
  "reviewer": "8d-eval-2026-05-16",
  "last_reviewed": "2026-05-16",
  "reviewed": true,
  "generated_at": "2026-04-24",
  "image": {
    "alt": "A flat vector illustration of a calm freshwater lake with a small snail silhouette near the shore, rendered in muted blue-green tones."
  },
  "attribution": "Likelier — https://likelier.app",
  "license": "https://creativecommons.org/licenses/by-sa/4.0/",
  "support": "https://buymeacoffee.com/kgluszczyk?via=likelier&utm_content=api-fear-single",
  "canonical_url": "https://likelier.app/schistosomiasis"
}