What are the odds of getting a fatal fox tapeworm infection from eating wild berries?
Evidence quality 4.88/5
Eight-dimension review score against the quality rubric . Each dimension scored 1–5.
- D1 Source grounding
- 4/5
- D2 Source authority
- 5/5
- D3 Arithmetic
- 5/5
- D4 Uncertainty
- 5/5
- D5 Scope
- 5/5
- D6 Prose
- 5/5
- D7 Perception honesty
- 5/5
- D8 Caveat completeness
- 5/5
Lifetime probability · lifetime, subgroup
1 in 8,475
0.01% lifetime chance
Most people overestimate this.
range 1 in 26,882 to 1 in 1,211
● your factors — click this risk ▾ to reveal
≈ As likely as
Perceived
The fear circulates widely in central Europe: a single unwashed raspberry or blueberry picked at fox-height could deliver Echinococcus multilocularis eggs that silently grow a parasitic tumor in the liver for years, often undetected until the disease is advanced. Health warnings routinely name wild berries and mushrooms as vectors, and the word "fox tapeworm" carries an outsized dread relative to how rare the actual disease is.
Rough estimate: many central Europeans estimate at least 1 in 1,000 risk for regular foragers
Source: editorial intuition, not polled
Actual
~0.20 per 100,000 per year (southwest Germany, 2012–2019)
adults in an endemic region of central Europe (southwest Germany)
Show derivation
Uses the most recent peer-reviewed incidence figure for an endemic European region: 0.20 cases per 100,000 per year in southwest Germany (2012–2019), from Graeter et al. (Infection 2020). That annual rate of 2.0 × 10^-6 per person, compounded over 59 adult years, yields 1 − (1 − 0.000002)^59 ≈ 0.000118, or about 1 in 8,500. This is the risk for an adult living in an actively endemic European region; the EU mean from the KNOW-PATH systematic review (1997–2023) is 0.063/100,000, yielding a lower-bound lifetime estimate of about 1 in 27,000. The Doubs département in France and Swiss Jura regularly record rates of 1.0–1.4/100,000, giving an upper-bound lifetime estimate of about 1 in 1,200. US adults face meaningfully lower baseline risk: Echinococcus multilocularis has limited US distribution (north-central states, Alaska), human cases are not nationally reportable, and recorded cases are sporadic — reliable US incidence data does not exist.
Caveats: This entry normalizes to an adult in an actively endemic European region (southw…
This entry normalizes to an adult in an actively endemic European region (southwest Germany, 2012–2019). The figure is not a US adult baseline — Echinococcus multilocularis has a restricted US range, human cases are not nationally reportable, and no reliable US incidence series exists. The number also does not distinguish the berry pathway from other routes: case-control meta-analyses find dog ownership and farming to be the statistically robust risk factors, while berry consumption carries a non-significant pooled OR of ~1.4. No_reliable_estimate is set to false because regional European incidence is well-documented — but the fraction attributable specifically to wild berry ingestion cannot be isolated from published data.
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Pick challenger
The surveillance numbers make alveolar echinococcosis (AE) genuinely rare, even in the European regions where the fox tapeworm is common. In southwest Germany — one of the most intensively monitored endemic areas on the continent — the annual incidence rose from 0.12 to 0.20 cases per 100,000 per year between 2004 and 2019, according to a 2020 referral-center study. Compounded over a 59-year adult life, that rate translates to a lifetime probability of roughly 1 in 8,500 for a person living in the region. The EU-wide mean, drawn from a 2025 systematic review of 4,207 European cases (1997–2023), sits lower at 0.063 per 100,000 per year — a lifetime figure closer to 1 in 27,000. By comparison, death from a bee or wasp sting has a US lifetime probability of about 1 in 8,000; being struck by lightning is roughly 1 in 280,000.
The specific fear — that picking and eating a low-growing wild berry could deliver the eggs — is scientifically plausible but epidemiologically weak. A 2017 meta-analysis of European case-control studies found that “eating unwashed strawberries” had a pooled odds ratio of 1.39 (95% CI 0.87–2.23, p = 0.17) and “eating wild vegetables and fruit” an OR of 1.38 (95% CI 0.90–2.10, p = 0.14) — neither statistically significant. The robust risk factors are dog ownership (especially dogs that kill game, OR ~18), agricultural work, and living in a rural dwelling near fields. Separately, a 2025 environmental review confirmed that Echinococcus DNA is detectable on 5–7% of strawberries and blueberries sampled in endemic European countries, but the viability of those eggs is explicitly unknown. The popular narrative naming berries as the dominant exposure route is not supported by the available case-control evidence.
The 1-in-8,500 figure applies only to residents of central European endemic zones — it is not a US adult baseline. Echinococcus multilocularis has a restricted North American range (primarily Alaska, north-central US, and Canada), human cases are not nationally reportable in the US, and no reliable national incidence series exists; published US cases are sporadic. Within Europe, regional variation spans more than an order of magnitude: from 0.034 per 100,000 in Austria to 1.4 per 100,000 in the Doubs département of France, where the lifetime probability approaches 1 in 1,200. The disease itself is severe — untreated AE carries a greater-than-90% fatality rate over 15 years — but modern benzimidazole treatment and surgical intervention have substantially improved outcomes when the condition is caught incidentally or symptomatic early.
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.
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[1] Infection (Springer); Graeter et al. — Spatial distribution and incidence trend of human alveolar echinococcosis in southwest Germany: increased incidence and urbanization of the disease?
Spatial distribution and incidence trend of human alveolar echinococcosis in southwest Germany: increased incidence and urbanization of the disease?- Statistic
Annual AE incidence per 100,000: 0.12 (2004–2011), rising to 0.20 (2012–2019) in southwest Germany- Excerpt
“"The data from our regional referral center for AE in southwest Germany suggest rising regional incidence for AE (annual incidence per 100,000 population 2004–2011: 0.12; 2012–2019: 0.20)." ”
- Source data from
- 2020-11-20
- Accessed
- 2026-05-01 · archived copy
- Calculation
- Anchor for native rate. 0.20 per 100,000 per year = 2.0 × 10^-6 annual hazard per person. Lifetime probability over 59 adult years: 1 − (1 − 0.000002)^59 = 0.000118 ≈ 1 in 8,475. Chosen as native because it is the most cited recent peer-reviewed figure for a well-defined endemic region with active surveillance.
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[2] PLOS Neglected Tropical Diseases; Piarroux et al. — Potential risk factors associated with human alveolar echinococcosis: Systematic review and meta-analysis
Potential risk factors associated with human alveolar echinococcosis: Systematic review and meta-analysis- Statistic
Meta-analysis OR for 'ate unwashed strawberries': 1.39 (95% CI 0.87–2.23, p=0.17, not significant); 'ate wild vegetables and fruit': OR 1.38 (95% CI 0.90–2.10, p=0.14, not significant). Strongest risk factors: dog ownership including dogs that hunt, farming, rural residence in endemic areas.- Excerpt
“"Results were not statistically significant for 'ate unwashed strawberries' (OR 1.39; 95% CI 0.87–2.23; p = 0.17), 'ate wild vegetables and fruit' (OR 1.38; 95% CI 0.90–2.10; p = 0.14) and 'ate mushrooms' (OR 0.72; 95% CI 0.38–1.39; p = 0.33)." ”
- Source data from
- 2017-08-01
- Accessed
- 2026-05-01 · archived copy
- Calculation
- Documents the epidemiological evidence (or lack thereof) for the berry transmission pathway. Non-significant ORs for berry and wild-produce consumption mean the published literature does not establish berries as a statistically confirmed transmission route. Strong risk factors (dog that hunts game, farmer status) are behaviorally distinct from foraging. Used to frame the gap between the popular fear narrative and the case-control evidence.
- Independence
- Systematic review pooling multiple European case-control studies — captures the dominant epidemiological evidence base for AE risk factors.
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[3] The Lancet Infectious Diseases — Unveiling the incidences and trends of alveolar echinococcosis in Europe: a systematic review from the KNOW-PATH project
Unveiling the incidences and trends of alveolar echinococcosis in Europe: a systematic review from the KNOW-PATH project- Statistic
Mean European AE incidence 1997–2023: 0.063 per 100,000; 4,207 cases documented; Germany, France, Austria, Switzerland = 68% of total- Excerpt
“"The mean annual incidence from 1997 to 2023 throughout Europe was 0.063 cases per 100,000 people. Historically endemic Austria, France, Germany, and Switzerland accounted for 2,864 (68.08%) of 4,207 cases documented in Europe." ”
- Source data from
- 2025-05-01
- Accessed
- 2026-05-01 · archived copy
- Calculation
- Provides the EU-wide mean annual incidence used as the lower bound of the uncertainty range. 0.063/100,000 = 6.3 × 10^-7 per year. Lifetime over 59y: 1 − (1 − 0.00000063)^59 ≈ 3.72 × 10^-5, i.e. ~1 in 26,900. Also confirms the 2025 state of European surveillance and the ongoing rising trend.
- Independence
- Independent systematic review from the KNOW-PATH project; uses ECDC TESSy surveillance data and national registries rather than single-center data.
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[4] Parasitology (Cambridge University Press) — Presence of Echinococcus eggs in the environment and food: a review of current data and future prospects
Presence of Echinococcus eggs in the environment and food: a review of current data and future prospects- Statistic
E. multilocularis DNA detected in 5.4% of strawberries and 7.3% of blueberries in European endemic countries (seven-country study); viability of those eggs explicitly unknown.- Excerpt
“"E. multilocularis DNA was detected in 1.2% of lettuces, 5.4% of strawberries, and 7.3% of blueberries in European endemic countries… although eggs are assumed to be the source of the DNA detected in these studies, the viability of such eggs is unknown." ”
- Source data from
- 2025-04-01
- Accessed
- 2026-05-01 · archived copy
- Calculation
- Documents the molecular evidence for berry contamination while underscoring the key limitation: DNA detection ≠ viable infectious eggs. Used to characterise the contamination pathway that underlies public concern, not to derive a probability estimate. Supports the framing that wild berries are a plausible but unconfirmed dominant transmission route.
- Independence
- Independent review of environmental contamination literature; distinct from the epidemiological case-control literature cited above.