CoChat
Sign Up
Cited by 45Parasitic Diseases Research and TreatmentHelminth infection and controlResearch on Leishmaniasis Studies

Prevalence and seasonal variations of canine dirofilariosis in Portugal

Open access
Alho, Ana Margarida, Landum, Miguel, Ferreira, Cátia, Meireles, José, Gonçalves, Luzia, de Carvalho, Luís Madeira, Belo, Silvana·2014·Veterinary Parasitology
DOI 10.1016/j.vetpar.2014.08.014
Open this paper in CoChat — free accountOpen PDF

Abstract

Dirofilariosis is a severe vector-borne emergent disease that is spreading worldwide and becoming a serious threat to human and veterinary public health. Portugal, a Mediterranean country, has favorable climate conditions for mosquito development and survival. At present, accurate data on the prevalence and epidemiological pattern of dirofilariosis in Portugal is scarce and outdated. To study these trends, a project was developed to assess the current prevalence of Dirofilaria immitis infection in shelter dogs as well as the prevalence of Dirofilaria species present in three coastal regions in central Portugal: Coimbra, Santarém, and Setúbal. Blood samples were collected from 696 shelter dogs during three consecutive years: 2011, 2012, and 2013. A rapid immunomigration technique was performed to detect female D. immitis antigens. Concurrently, to detect and identify circulating microfilariae, a modified Knott's technique and acid phosphatase histochemical staining were also performed. Of the 696 dogs sampled, 105 were positive for D. immitis, with an overall prevalence of 15.1%. Forty of the 105 dogs were antigen negative but were positive for D. immitis microfilariae. Three animals were co-infected with D. immitis and Acanthocheilonema dracunculoides, and there was also one dog infected only with A. dracunculoides, all confirmed by polymerase chain reaction. The highest prevalence of canine heartworm during the 3-y period was in Setúbal (24.8%), followed by Coimbra (13.8%), and Santarém (13.2%), with significant inter-district differences. Our results demonstrate a higher prevalence of dirofilariosis compared with findings of previous studies and show an increasing rate of infection in the southern areas of Portugal attributed, at least in part, to bioclimatic and ecological factors. The present study updates the epidemiological situation and correlates the risk of dirofilariosis transmission within each region. These findings are highly relevant to both human and veterinary public health, contributing to the general awareness of pet owners and veterinarian practitioners and reinforcing the need for effective control measures against vectors and preventive therapy in companion animals.

AI snapshot

Written from the paper’s full text.

TL;DR

In a 3-year survey of 696 shelter dogs in central Portugal, canine Dirofilaria immitis prevalence was 15.1%, with significant regional variation and highest prevalence in Setúbal (24.8%). Transmission was seasonal (May–November) and all districts had suitable temperature conditions for Dirofilaria development.

Key findings

Overall D. immitis prevalence was 15.1% (105/696) across 2011–2013; antigen-positive dogs were 9.4% (65/696), microfilariae by modified Knott’s were 12.9% (90/696), and acid phosphatase staining was 12.1% (84/696). Regional prevalence differed significantly (χ²=8.661; p=0.013): Setúbal 24.8% (25/101), Coimbra 13.8% (31/224), and Santarém 13.2% (49/371); the highest yearly rate was 33.3% in Setúbal in 2013 and the lowest was 11.5% in Santarém in 2012. Infection was higher in males (18.2% [56/307]) than females (12.6% [49/389]; p=0.039) and in dogs ≥5 years (p=0.026), while coat length was not significant (p=0.178). Three dogs were co-infected with D. immitis and Acanthocheilonema dracunculoides, one dog was infected only with A. dracunculoides, and no D. repens or A. reconditum was detected; the temperature-based model estimated 150.7 transmission days/year in Santarém, 150.3 in Setúbal, and 129.7 in Coimbra, with seasonal risk from May to November.

Methods

Cross-sectional survey of 696 shelter dogs in nine animal shelters in Coimbra, Santarém, and Setúbal, sampled in October/November 2011, April/May 2012, and May/June 2013; dogs younger than 6 months were excluded and only dogs admitted in the previous 6 months were included. Diagnostic testing used the WITNESS Dirofilaria rapid immunomigration antigen test, modified Knott’s technique, acid phosphatase histochemical staining (Leucognost SP), and PCR with panfilarial primers DIDR-F1/DIDR-R1 plus sequencing for confirmation. Analysis used SPSS v21 and EpiTools, Pearson chi-square for gender, coat length, and age groups, Agresti-Coull prevalence estimates, and a degree-day model based on Dirofilaria Development Units with a 14°C threshold, 130 cumulative DDUs, and 30-day mosquito life expectancy.

Limitations

The paper states that all sampled dogs were strays from shelters with no routine heartworm preventive treatment and no information on prior preventive treatments, which may limit generalizability and may explain the higher prevalence found. The authors state that the transmission risk model used temperature-based DDUs only and note that other factors such as precipitation, relative humidity, vegetation indices, population density, and socioeconomic status also influence transmission, recommending an integrated approach. Evident from the text: antigen testing followed manufacturer instructions without heat treatment, and the authors discuss antigen–antibody complex formation as a possible cause of false-negative antigen results; acid phosphatase staining was sometimes dubious due to low microfilariae burden or faint blood smears.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1016/j.vetpar.2014.08.014

Cites

Statistics

Nothing to recompute.

Claims the paper makes

0 of 28 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    The antigen detection test was positive for D. immitis in 9.4% (65/696) of shelter dogs tested over the 3-year period.

    “Of the 696 shelter dogs tested over the 3-y period, 9.4% (65/696) were positive for D. immitis based on the antigen detection test (Table 1).”
    Quote in the paperSubstantial claim
  • Findingown data

    Dirofilaria was detected in all three districts in each of the years surveyed.

    “Dirofilaria was detected in all three districts in each of the years surveyed.”
    Quote in the paperNot a substantial claim
  • Findingown data

    Prevalence of D. immitis in Setúbal over the 3-year study was 24.8% (25/101), 95% CI 17.3-34.0%.

    “with the highest prevalence found in Setúbal (24.8% [25/101]) [95% CI: 17.3-34.0%]”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The sampled shelter dogs are representative of the shelter dog population in the three districts.
    • Rests on an assumption: The same nine animal shelters tested each year are representative of the three districts.
  • Findingown data

    The lowest infection rate, 11.5%, was recorded in 2012 in the Santarém area.

    “and the lowest 11.5% was recorded in 2012, in the Santarém area (Table 1; Fig. 3).”
    Quote in the paperNot a substantial claim
  • Findingown data

    In 49 (46.7%) of the 105 D. immitis-infected dogs, antigen testing and acid phosphatase staining both produced positive results.

    “In 49 (46.7%) of the 105 D. immitis-infected dogs, antigen testing and acid phosphatase staining both produced positive results.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 17
  • Classified as probably not a substantial claim. 9
  • The quote only partly states this claim. 1

  • May combine two claims.

    Findingown data

    Discordant results were found in 41 samples (38.7%), with positive results detected by acid phosphatase staining, which were later confirmed by PCR analysis.

    “Similarly, discordant results were found in 41 samples (38.7%), with positive results detected by acid phosphatase staining, which were later confirmed by PCR analysis (Table 1).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Infected animals were identified in all age groups: <5 y = 11.7% (44/376); 5-10 y = 19.2% (48/250); and >10 y = 18.6% (13/70).

    “Infected animals were identified in all age groups: <5 y = 11.7% (44/376); 5-10 y = 19.2%(48/250), and [>10 y old = 18.6% (13/70)].”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Short-haired dogs were more frequently infected (16.7%; 65/389) than long-haired dogs (13.0%; 40/307), but the difference was not statistically significant (χ2 = 1.814; p = 0.178).

    “Additionally, short-haired dogs were more frequently infected (16.7%; 65/389) than long-haired (13.0%; 40/307), although the length of dog coat was not a statistically significant factor ( 2 = 1.814; p = 0.178).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Of the 41 microfilaria-positive antigen-negative samples, 37 were identified as single infection with D. immitis, one as single infection with A. dracunculoides, and three were A. dracunculoides and D. immitis coinfections.

    “Of these 41 samples, 37 were identified as single infection with D. immitis, one as single infection with A. dracunculoides; the remaining three were A. dracunculoides and D. immitis coinfections.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Infected animals were found in eight of the nine shelters assessed (88.9%), with prevalence ranging from 5.8% to 31.9% in each shelter.

    “Infected animals were found in eight of the nine shelters assessed (88.9%) with prevalence ranging from 5.8% to 31.9% in each shelter.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The earliest and latest period for Dirofilaria transmission during the 3 years ranged from May 21 to November 14 in Santarém, from May 20 to November 6 in Setúbal, and from May 29 to November 2 in Coimbra.

    “The earliest and latest period for Dirofilaria transmission registered during the 3 y ranged from May 21st to November 14th in Santarém, from May 20th to November 6th in Setúbal, and from May 29th to November 2nd in Coimbra.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The temperature data from the three Portuguese meteorological stations are representative of the climatic conditions in the corresponding districts (Coimbra, Santarém, Setúbal).

  • May combine two claims.

    Findingown data

    The average number of days with conditions for Dirofilaria transmission in Coimbra was 129.7 days/y, with four estimated Dirofilaria generations.

    “and Coimbra (129.7 days/y, four estimated Dirofilaria generations).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The temperature data from the three Portuguese meteorological stations are representative of the climatic conditions in the corresponding districts (Coimbra, Santarém, Setúbal).

  • May combine two claims.

    Findingown data

    The average number of days with conditions for Dirofilaria transmission in Setúbal was 150.3 days/y, with five estimated Dirofilaria generations.

    “followed by Setúbal (150.3 days/y, five estimated Dirofilaria generations);”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The temperature data from the three Portuguese meteorological stations are representative of the climatic conditions in the corresponding districts (Coimbra, Santarém, Setúbal).

  • May combine two claims.

    Findingown data

    The maximum number of potential transmission days/y (n = 169.7) occurred in 2011, followed by 2013 (n = 133.3) and 2012 (n = 132.7).

    “The maximum number of potential transmission days/y (n = 169.7)occurred in 2011, followed by 2013 (n = 133.3)and 2012 (n = 132.7).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The temperature data from the three Portuguese meteorological stations are representative of the climatic conditions in the corresponding districts (Coimbra, Santarém, Setúbal).

  • May combine two claims.

    Interpretationown data

    Dirofilaria infection is increasing and expanding in Portugal.

    “suggesting that Dirofilaria infection is increasing and expanding in Portugal.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The prevalence estimates from this study can be compared with previous studies conducted in different dog populations and using different diagnostic methods.

  • May combine two claims.

    Premisenone given

    Canine dirofilariosis is endemic in mainland Portugal as well as in Madeira Island.

    “Canine dirofilariosis is endemic in mainland Portugal as well as in Madeira Island.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    D. immitis infection is endemic and continuously transmitted in the three districts studied (Coimbra, Santarém, and Setúbal) from 2011 to 2013.

    “D. immitis was detected in all three districts studied from 2011 to 2013, confirming the endemicity and continuous transmission of this life-threatening disease.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    The number of animals required was estimated using WinEpi program (stratified sample approach), taking into account the global prevalence of canine dirofilariosis in each district and the average number of animals in the shelters.

    “The number of animals required was estimated using WinEpi program (stratified sample approach), taking into account the global prevalence of canine dirofilariosis in each district as well as the average number of animals in the shelters.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Based exclusively on microfilariae detection, without species differentiation, prevalence rates of 16.7% in Ribatejo, 16.5% in Alentejo, 12% in Algarve, and 30% in Madeira were found.

    “Based exclusively on microfilariae detection, without species differentiation, prevalence rates of 16.7% in Ribatejo, 16.5% in Alentejo, 12% in Algarve, and 30% in Madeira were found (Araújo, 1996).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Araújo, 1996

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    Only dogs admitted to the kennels in the previous 6 months were included in the survey to preclude evaluating the same animal in subsequent years.

    “Only dogs admitted to the kennels in the previous 6 months were included in the survey to preclude evaluating the same animal in subsequent years.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    D. immitis also has been reported in three European otters Lutra lutra in Portuguese natural freshwater ecosystems.

    “Additionally, D. immitis also has been reported in three European otters Lutra lutra in Portuguese natural freshwater ecosystems (Torres et al., 2004;Saraiva et al., 2012).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Torres et al., 2004

      Not checked in the free run.

    • cites Saraiva et al., 2012

      Not checked in the free run.

  • May combine two claims. The quote only partly states this claim.

    Interpretationcitation

    The lower sensitivity of the antigen test was unexpected, although similar findings have been reported by Tarello (2001) and Vezzani et al. (2008).

    “The lower sensitivity of the antigen test was unexpected, although similar findings have also been reported by Tarello (2001), who found seven dogs in Italy harboring D. immitis microfilariae that tested negative for D. immitis antigen.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Tarello (2001)

      Not checked in the free run.

    • cites Vezzani et al. (2008)

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    All microfilaremic samples that either tested positive for D. immitis or were in doubt by the modified Knott's technique and acid phosphatase staining but were negative for D. immitis circulating antigens were subjected to molecular techniques to confirm diagnosis.

    “Some microfilaremic samples that either tested positive for D. immitis or were in doubt by the modified Knott's technique and acid phosphatase staining were negative for D. immitis circulating antigens.For this reason and to ensure an accurate analysis, all of these samples were subjected to molecular techniques to confirm its diagnosis.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    In Portugal, only Culex theileri was found to be naturally infected with Dirofilaria spp. larvae.

    “In Portugal, only Culex theileri was found to be naturally infected with Dirofilaria spp.larvae.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Ribeiro et al., 1983

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Recent data from Cardoso et al. (2012) reported the national average prevalence of D. immitis in apparently healthy dogs to be 3.6% and 8.9% in dogs suspected to have clinical signs associated with canine vector-borne disease.

    “Recent data from Cardoso et al. (2012) using a commercial ELISA kit (SNAP ® 4Dx ® , IDEXX Laboratories, Inc., Westbrook, Maine, USA) reported the national average prevalence of D. immitis in apparently healthy dogs to be 3.6% and 8.9% in dogs suspected to have clinical signs associated with canine vector-borne disease.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Cardoso et al. (2012) source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    Dogs younger than 6 months were excluded due to the long life cycle of D. immitis.

    “Dogs younger than 6 months were excluded due to the long life cycle of D. immitis.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    In 2011, Balreira et al. reported a 2.1% seroprevalence of canine Dirofilaria infection in northern and north central Portugal, with higher rates in Aveiro (6.8%) and Coimbra (8.8%).

    “In 2011, Balreira et al. reported a 2.1% seroprevalence of canine Dirofilaria infection in northern and north central Portugal, with higher rates in Aveiro (6.8%) and Coimbra (8.8%).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Balreira et al.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationcitation

    Occult infections may be due to several factors, such as prepatency, unisex infection (by female worms), drug-induced sterility of adult filariae, or immune-mediated clearance of microfilariae.

    “According to Genchi et al. (2007), occult infections may be due to several factors, such as prepatency, unisex infection (by female worms), drug-induced sterility of adult filariae, or immune-mediated clearance of microfilariae.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Genchi et al. (2007)

      Not checked in the free run.

23 of 23

  • The paper relies on this without support.

    There are no published data on seasonal dirofilariosis transmission trends in Portugal.

    “There are no published data on seasonal dirofilariosis transmission trends in Portugal.”

  • The paper relies on this without support.

    The temperature data from the three Portuguese meteorological stations are representative of the climatic conditions in the corresponding districts (Coimbra, Santarém, Setúbal).

    “Minimum and maximum daily temperatures registered in the three respective Portuguese meteorological stations were obtained from Instituto Português do Mar e da Atmosfera (IPMA).”

  • The paper relies on this without support.

    The sampled shelter dogs are representative of the shelter dog population in the three districts.

    “A total of 696 shelter dogs, including 307 males (44.1%) and 389 females (55.9%), were randomly selected (Table 1).”

  • The paper relies on this without support.

    The prevalence estimates from this study can be compared with previous studies conducted in different dog populations and using different diagnostic methods.

    “This prevalence was higher than expected when taking into account findings of previous studies conducted in central Portugal (Araújo, 1996;Balreira et al., 2011;Cardoso et al., 2012).”

  • The paper relies on this without support.

    The same nine animal shelters tested each year are representative of the three districts.

    “The same nine animal shelters were tested each year (October/November 2011, April/May 2012, May/June 2013) to determine trends in the prevalence of Dirofilaria spp. in these regions.”
5 of 5

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • In Portugal, the prevalence of canine heartworm reported in the past has remained at similar percentages and has even increased in some regions.

    “In Portugal, the prevalence reported in the past has remained at similar percentages and has even increased in some regions.”

    From What has happened to heartworm disease in Europe in the last 10 years? (2022) · cites this paper as [12]

  • In central coastal regions of Portugal, canine heartworm prevalence has been reported at 15.1%, while in the central region it ranged from 8.8 to 27.3%.

    “Other studies have reported prevalence of 15.1% in the central coastal regions of Portugal, while in the central region, prevalence ranged from 8.8 to 27.3% [12,13,14]”

    From What has happened to heartworm disease in Europe in the last 10 years? (2022) · cites this paper as [12]

  • In neighbouring Portugal, canine dirofilariosis is endemic with an overall national seroprevalence of 2.1%-15.1%.

    “In neighbouring Portugal, canine dirofilariosis is endemic with an overall national seroprevalence of 2.1%- 15.1% ( Alho et al., 2014 and Vieira et al., 2015).”

    From Culex pipiens as a potential vector for transmission of Dirofilaria immitis and other unclassified Filarioidea in Southwest Spain (2016) · cites this paper as Alho et al., 2014

  • Rice field abundance was acknowledged as one of the possible elements contributing to the higher Dirofilaria infection rates in certain areas of Portugal.

    “Rice field abundance was acknowledged as one of the possible elements contributing to the higher Dirofilaria infection rates in certain areas of Portugal [24].”

    From Dirofilaria infections in dogs in different areas of Greece (2016) · cites this paper as [24]

  • Canine dirofilariosis due to D. immitis is known to be endemic and widely distributed in Portugal, with prevalence ranging between 0.9 and 27.3% in mainland regions to over 30% in Madeira Island.

    “Canine dirofilariosis due to D. immitis is known to be endemic and widely distributed in Portugal, with prevalence ranging between 0.9 and 27.3% in mainland regions to over 30% in Madeira Island [22–25]”

    From Molecular characterization of Dirofilaria spp. circulating in Portugal (2017) · cites this paper as [25]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

  • Acid phosphatase-positive groups exceed the stated total

    Minor

    The results describe 49 dogs positive on both antigen testing and acid phosphatase staining and 41 discordant dogs positive on acid phosphatase staining. These disjoint groups total 90, exceeding the stated 84 animals with positive acid phosphatase staining.

    Reported 84 · recomputed 90

1 of 1

The citation lists haven’t been fetched yet

References 29 · Cited by 45

Research works printed but not linked: 7

  1. Araújo, 1996, Canine and human Dirofilaria immitis infections in Portugal. A review, Parassitologia, 38, 366
  2. Carvalho-Varela, 1993, A helmintofauna da raposa (Vulpes vulpes silacea Miller, 1907) in Portugal, Acta Parasitol. Port., 1, 73
  3. Carvalho-Varela, 1993, Some ecological aspects of the helminthic fauna of the red fox (Vulpes vulpes L.) of the Palearctic Zone. II – Vulpine Iberian populations, Acta Parasitol. Port., 1, 81
  4. Gomes, 2003, Acta Parasitol. Port., 10, 10
  5. Guerrero, 1989, Estudio de la incidencia de la enfermedad del gusano del corazón en la población canina Española, Med. Vet., 6, 217
  6. Ribeiro, 1983, Contribuição para o Estudo dos Vectores das Filaríases Animais em Portugal, J. Soc. Cienc. Med., 147, 143
  7. Tarello, 2001, Importance in the dog of concentration tests for the diagnosis of heartworm disease in non-endemic areas, Vet On-Line, 2

Authors
Alho, A. M., Landum, M., Ferreira, C., Meireles, J., Gonçalves, L., de Carvalho, L. M., & Belo, S.
Affiliations
  • University of Lisbon (PT)
  • Universidade Nova de Lisboa (PT)
Corresponding author
Alho, Ana Margarida
ORCID
Venue
Veterinary Parasitology
Publisher
Elsevier BV
Published
2014-11
Volume
206
Issue
1-2
Pages
99-105
ISSN
0304-4017 (ISSN-L)
DOI
10.1016/j.vetpar.2014.08.014
OpenAlex
W1966437261
Semantic Scholar
e6d90cdb2bf712af59a831ce5301c74211d6f7b2
Cited by
45
References
29
Citations by year
2026: 1 · 2025: 2 · 2024: 2 · 2023: 4 · 2022: 4 · 2021: 3 · 2020: 4 · 2019: 6 · 2018: 3 · 2017: 4 · 2016: 10 · 2015: 2
FWCI
3.74
Type
journal article
Language
en
Open access
Licence
Locations
  • Veterinary Parasitology (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
Funders
Fundação para a Ciência e Tecnologia (FCT) (SFRH/BD/85427/2012)
Topics
  • Health Sciences › Medicine › Infectious Diseases › Parasitic Diseases Research and Treatment
  • Health Sciences › Veterinary › Small Animals › Helminth infection and control
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Research on Leishmaniasis Studies
Keywords
canine dirofilariasis, Dirofilaria immitis, heartworm disease, prevalence, seasonal variation, shelter dogs, microfilariae, antigen detection, co-infection, vector-borne diseases, Portugal, coastal areas, bioclimatic factors
MeSH terms
Animals, Dirofilaria immitis, Dirofilariasis, Dog Diseases, Dogs, Female, Male, Portugal, Seasons, Prevalence

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-09.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review