According to the international animal health authority, i.e., the World Organization on Animal Health (WOAH, former OIE), circoviruses are part of the Circoviridae family, which only includes 2 genera Circovirus and Cyclovirus, and infect swine, canine, ursid, viverrid, felid, pinniped, herpestid, mustelid, and several avian species (WOAH 2021). They are small (12–27 nm), non-enveloped, circular, single-stranded DNA viruses, viral replication is nuclear, and wild and domestic birds and mammals could serve as natural hosts. If most infections caused by circoviruses are subclinical in both wild and domestic species, they can be responsible for severe diseases in the commercial pig industry due to the Porcine circovirus-2 (PCV-2). These viruses can constitute a threat to wildlife, and cause their hosts to become immunocompromised, and animals often present with secondary coinfections. 

Canine circoviruses (CanineCV) harbour a worldwide distribution in dogs, and is the sole member of the viral genus to infect canines. They can be detected in wild carnivores, such as wolves, badgers, foxes and jackals, which indicates an ability for cross-species transmission between wildlife and domestic dogs. However, fox circovirus (FoCV), a distinct lineage of CanineCV, has been identified exclusively in wild canids (foxes and wolves) and not in dogs in Europe and North America, where it can cause in red foxes meningoencephalitis and other central nervous system signs. 

In their article, Canuti et al. (2024) investigate the presence, distribution and ecology of CanineCV in grey wolf specimens from the Northwest Territories, Canada. CanineCV occurrence appears to be relatively high with 45.3% positive specimens and parvoviral superinfections observed. The authors identify a high CanineCV genetic diversity among the investigated grey wolf specimens, and exacerbated by viral recombination. Phylogenetic analysis reveals the existence of 4 lineages, within each of them strains segregate by geography and not by host origin. This observed geographic segregation is interpreted as being due to the absence of exchange flows between grey wolf host subpopulations.  Due to the paucity of knowledge on these circoviruses in wildlife and at the interface between wild and domestic animals, the authors discuss the plausible role of wolves as natural host reservoirs for disease transmission due to long-lasting virus-host coevolution. They are also conscious that additional maintenance hosts could exist in the wild, claiming for further studies to decipher fox circovirus disease ecology and transmission dynamics.

This study underlines the importance of better understanding the transmission ecology and evolution of these Canine circoviruses, and I can only agree. Xiao et al. (2023), a research not referred to in the present work, evidenced CanineCV infection in cats in China, and obtained the first whole genome of cat-derived CanineCV. This emphasizes the importance of monitoring additional animal species and locations in the world to clarify disease ecology and transmission dynamics. A broader sampling of a wide range of animal species in different parts of the world using a species community-based approach is the key to understanding these CanineCV infections.

References

Marta CANUTI, Abigail V.L. KING, Giovanni FRANZO, H. Dean CLUFF, Lars E. LARSEN, Heather FENTON, Suzanne C. DUFOUR, Andrew S. LANG. 2024. Diverse fox circovirus (Circovirus canine) variants circulate at high prevalence in grey wolves (Canis lupus) from the Northwest Territories, Canada. bioRxiv, ver. 2 peer-reviewed and recommended by Peer Community in Infections. https://doi.org/10.1101/2024.03.08.584028

World Organization on Animal Health. 2021. Circoviruses.  https://www.woah.org/app/uploads/2021/05/circoviruses-infection-with.pdf [consulted on July 9th, 2024].

Xiangyu XIAO, Yan CHAO LI, Feng PEI XU, Xiangpi HAO, Shoujun LI, Pei ZHOU. 2023. Canine circovirus among dogs and cats in China: first identification in cats. Front. Microbiol. 14. https://doi.org/10.3389/fmicb.2023.1252272

Despite decades of advances and understanding of the indiscriminate nature of human immunodeficiency virus (HIV), it remains shrouded in stigma that makes it difficult to reach some key populations at risk of transmission. The advent of self-testing technology for HIV (HIVST) has opened much-needed potential for bringing privacy to prevention that is crucial for curtailing its continued spread (Johnson et al., 2014). The HIV Self-Testing in Africa (STAR) Initiative (https://www.psi.org/fr/project/star/), carried out in Eastern and Southern Africa between 2015 and 2020 (Simwinga et al., 2022), demonstrated the market and public health operational potential of HIVST of different distribution methods. From 2019 to 2022, the “AutoTest de dépistage du VIH : Libre d’Accéder à la connaissance de son Statut" (ATLAS, translating to “HIVST: Freedom to know your status”) program built on these findings to quantify the public health value of HIVST for reaching key populations in West Africa (specifically, Mali, Senegal and Côte d’Ivoire) (Ky-Zerbo et al., 2022).

The innovative secondary distribution methods these studies employed, where the primary targeted populations were also encouraged to take and provide tests to their contacts, helped widen the reach of HIVST within key population networks beyond those relying on access to HIV testing facilities.

The tricky part of the self-testing model lies in assessing its reach and impact while maintaining the privacy of self-testers that is central to its success. Following voluntary phone survey methods that previously were able to show expanded reach of HIVST to first-time testers in key populations in West Africa and high rates of confirmatory testing and treatment seeking (Kra et al., 2022), Kra et al. (Kra et al., 2024) quantified how many of these self-tests led to a positive result – allowing wider assessment of follow-up behaviors and positivity rates among the hard-to-reach populations the program had targeted. 

While the numbers were low, the results were informative. Among respondents who reported a positive (“reactive”) HIVST, just 44% proceeded to confirmatory testing. This is lower than in other populations where HIVST follow-up has been assessed (Thirumurthy et al., 2016). The main reasons given for not confirming a reactive self-test was misinterpretation of HIVST results and not understanding that confirmatory testing was needed. The result thus highlighted a need for improved communication on how to correctly interpret HIVST results, and the authors provided ranges for how this misinterpretation could have affected their positivity estimates. However, the majority of those who sought confirmatory testing did so within 3 months, and nearly all of those with confirmed infection started on treatment. HIV positivity rates in the three countries were all higher than other published HIV positivity estimates (Giguère et al., 2021; Maheu-Giroux et al., 2019), suggesting that HIVST methods were highly effective at reaching the targeted communities. 

Finally, while the authors demonstrated their methods as an effective way of assessing the utility of HIVST campaigns and identifying ways to improve them, the follow-up surveys are likely too costly to replace current passive surveillance methods for assessing community disease burden. That said, these precious data should be taken as validation of the public health value of HIV self-testing in key populations across communities in West Africa. With improvements in communicating instructions for use and follow-up, there is little doubt that the innovation of HIVST primary and secondary distribution could become a widely useful addition to the fight against HIV. 

References

Giguère, K., Eaton, J. W., Marsh, K., Johnson, L. F., Johnson, C. C., Ehui, E., Jahn, A., Wanyeki, I., Mbofana, F., Bakiono, F., Mahy, M., & Maheu-Giroux, M. (2021). Trends in knowledge of HIV status and efficiency of HIV testing services in sub-Saharan Africa, 2000–20: a modelling study using survey and HIV testing programme data. The Lancet HIV, 8(5), e284–e293. https://doi.org/10.1016/S2352-3018(20)30315-5

Johnson, C., Baggaley, R., Forsythe, S., Van Rooyen, H., Ford, N., Napierala Mavedzenge, S., Corbett, E., Natarajan, P., & Taegtmeyer, M. (2014). Realizing the potential for HIV self-testing. In AIDS and Behavior (Vol. 18, Issue SUPPL. 4). Springer New York LLC. https://doi.org/10.1007/s10461-014-0832-x

Kra, A. K., Fosto, A. S., N’guessan, K. N., Geoffroy, O., Younoussa, S., Kabemba, O. K., Gueye, P. A., Ndeye, P. D., Rouveau, N., Boily, M. C., Silhol, R., d’Elbée, M., Maheu-Giroux, M., Vautier, A., & Larmarange, J. (2022). Can HIV self-testing reach first-time testers? A telephone survey among self-test end users in Côte d’Ivoire, Mali, and Senegal. BMC Infectious Diseases, 22. https://doi.org/10.1186/s12879-023-08626-w

Kra, A. K., Fotso, A. S., Rouveau, N., Maheu-Giroux, M., Boily, M.-C., Silhol, R., d’Elbée, M., Vautier, A., Lamarange, J., & the Atlas team. (2024). HIV self-testing positivity rate and linkage to confirmatory testing and care: a telephone survey in Côte d’Ivoire, Mali, and Senegal. MedRxiv, Ver. 4 Peer-Reviewed and Recommended by Peer Community in Infections, 2023.06.10.23291206. https://doi.org/https://doi.org/10.1101/2023.06.10.23291206

Ky-Zerbo, O., Desclaux, A., Boye, S., Maheu-Giroux, M., Rouveau, N., Vautier, A., Camara, C. S., Kouadio, B. A., Sow, S., Doumenc-Aidara, C., Gueye, P. A., Geoffroy, O., Kamemba, O. K., Ehui, E., Ndour, C. T., Keita, A., & Larmarange, J. (2022). “I take it and give it to my partners who will give it to their partners”: Secondary distribution of HIV self-tests by key populations in Côte d’Ivoire, Mali, and Senegal. BMC Infectious Diseases, 22. https://doi.org/10.1186/s12879-023-08319-4

Maheu-Giroux, M., Marsh, K., Doyle, C. M., Godin, A., Lanièce Delaunay, C., Johnson, L. F., Jahn, A., Abo, K., Mbofana, F., Boily, M. C., Buckeridge, D. L., Hankins, C. A., & Eaton, J. W. (2019). National HIV testing and diagnosis coverage in sub-Saharan Africa: A new modeling tool for estimating the “first 90” from program and survey data. AIDS, 33, S255–S269. https://doi.org/10.1097/QAD.0000000000002386

Simwinga, M., Gwanu, L., Hensen, B., Sigande, L., Mainga, M., Phiri, T., Mwanza, E., Kabumbu, M., Mulubwa, C., Mwenge, L., Bwalya, C., Kumwenda, M., Mubanga, E., Mee, P., Johnson, C. C., Corbett, E. L., Hatzold, K., Neuman, M., Ayles, H., & Taegtmeyer, M. (2022). Lessons learned from implementation of four HIV self-testing (HIVST) distribution models in Zambia: applying the Consolidated Framework for Implementation Research to understand impact of contextual factors on implementation. BMC Infectious Diseases, 22(Suppl 1). https://doi.org/10.1186/s12879-024-09168-5

Thirumurthy, H., Masters, S. H., Mavedzenge, S. N., Maman, S., Omanga, E., & Agot, K. (2016). Promoting male partner HIV testing and safer sexual decision making through secondary distribution of self-tests by HIV-negative female sex workers and women receiving antenatal and post-partum care in Kenya: a cohort study. The Lancet HIV, 3(6), e266–e274. https://doi.org/10.1016/S2352-3018(16)00041-2

Various species of Ebolavirus have caused, and are still causing, zoonotic outbreaks and public health crises in Africa. Bats have long been hypothesized to be important reservoir populations for a series of viruses such as Hendra or Marburg viruses, the severe acute respiratory syndrome coronavirus (SARS-CoV, SARS-CoV-2) as well as Ebolaviruses [2, 3]. However the ecology of disease dynamics, disease transmission, and coevolution with their natural hosts of these viruses is still poorly understood, despite their importance for predicting novel outbreaks in human or livestock populations. The evidence that bats function as sylvatic reservoirs for Ebola viruses is yet only partial. Indeed, only few serological studies demonstrated the presence of Ebolavirus antibodies in young bats [4], albeit without providing positive controls of viral detection or identifying the viral species (via PCR). There is thus an unexplained discrepancy between serological data and viral detection [2, 4]. 

In this article, Pleydell et al. [1] use a modeling approach as well as published serological and age-structure (of the bat population) data to calibrate the model simulations. The study starts with the development of an age-structured epidemiological model which includes seasonal birth pulses and waning immunity, both generating pulses of Ebolavirus transmission within a colony of African straw-coloured fruit bats (Eidolon helvum). The epidemiological dynamics of such system of ordinary differential equations can generate annual outbreaks, skipped years or multi-annual cycles up to chaotic dynamics. Therefore, the calibration of the parameters, and the definition of biologically relevant priors, are key. To this aim, the serological data are obtained from a previous study in Cameroon [5], and the age structured of the bat population (birth and mortality) from a population study in Ghana [6]. These data are integrated into the Bayesian analysis and statistical framework to fit the model and generate predictions. In a nutshell, the authors show an overlap between the data and credibility intervals generated by the calibrated model, which thus explains well the seasonality of age-structure, namely changes in pup presence, number of lactating females, or proportion of juveniles in May. The authors can estimate that 76% of adults and 39% of young bats do survive each year, and infections are expected to last one and a half weeks. The epidemiological model predicts that annual birth pulses likely generate annual disease outbreaks, so that weeks 30 to 31 of each year, are predicted to be the best period to isolate the circulating Ebolavirus in this bat population. From the model predictions, the authors estimate the probability to have missed an infectious bat among all the samples tested by PCR being approximately of one per two thousands. The disease dynamics pattern observed in the serology data, and replicated by the model, is likely driven by seasonal pulses of young susceptible bats entering the population. This seasonal birth event increases the viral transmission, resulting in the observed peak of viral prevalence. With the inclusion of immunity waning and antibody persistence, the model results illuminate therefore why previous studies have detected only few positive cases by PCR tests, in contrast to the evidence from serological data. 

 This study provides a first proof of principle that epidemiological modeling, despite its many simplifying assumptions, can be applied to wild species reservoirs of zoonotic diseases in order to optimize the design of field studies to detect viruses. Furthermore, such models can contribute to assess the probability and timing of zoonotic outbreaks in human or livestock populations. This article illustrates one of the manifold applications of mathematical theory of disease epidemiology to optimize sampling of pathogens/parasites or vaccine development and release [7, 8]. The further coupling of such models with population genetics theory and statistical inference methods (using parasite genome data) increasingly provide insights into the adaptation and evolution of parasites to human, crops and livestock populations [9, 10].

References

[1] Pleydell D.R.J., Ndong Bass I., Mba Djondzo F.A., Djomsi D.M., Kouanfack C., Peeters M., and J. Cappelle. 2023. A Bayesian analysis of birth pulse effects on the probability of detecting Ebola virus in fruit bats. bioRxiv, ver. 3 peer reviewed and recommended by Peer Community In Infections. https://doi.org/10.1101/2023.08.10.552777

[2] Caron A., Bourgarel M., Cappelle J., Liégeois F., De Nys H.M., and F. Roger. 2018. Ebola virus maintenance: if not (only) bats, what else? Viruses 10, 549. https://doi.org/10.3390/v10100549

[3] Letko M., Seifert S.N., Olival K.J., Plowright R.K., and V.J. Munster. 2020. Bat-borne virus diversity, spillover and emergence. Nature Reviews Microbiology 18, 461–471. https://doi.org/10.1038/s41579-020-0394-z

[4] Leroy E.M., Kumulungui B., Pourrut X., Rouquet P., Hassanin A., Yaba P., Délicat A., Paweska J.T., Gonzalez J.P., and R. Swanepoel. 2005. Fruit bats as reservoirs of Ebola virus. Nature 438, 575–576. https://doi.org/10.1038/438575a

[5] Djomsi D.M. et al. 2022. Dynamics of antibodies to Ebolaviruses in an Eidolon helvum bat colony in Cameroon. Viruses 14, 560. https://doi.org/10.3390/v14030560

[6] Peel A.J. et al. 2016. Bat trait, genetic and pathogen data from large-scale investigations of African fruit bats Eidolon helvum. Scientific data 3, 1–11. https://doi.org/10.1038/sdata.2016.49

[7] Nyandjo Bamen H.L., Ntaganda J.M., Tellier A. and O. Menoukeu Pamen. 2023. Impact of imperfect vaccine, vaccine trade-off and population turnover on infectious disease dynamics. Mathematics, 11(5), p.1240. https://doi.org/10.3390/math11051240

[8] Saadi N., Chi Y.L., Ghosh S., Eggo R.M., McCarthy C.V., Quaife M., Dawa J., Jit M. and A. Vassall. 2021. Models of COVID-19 vaccine prioritisation: a systematic literature search and narrative review. BMC medicine, 19, pp.1-11. https://doi.org/10.1186/s12916-021-02190-3

[9] Maerkle, H., John S., Metzger, L., STOP-HCV Consortium, Ansari, M.A., Pedergnana, V. and Tellier, A., 2023. Inference of host-pathogen interaction matrices from genome-wide polymorphism data. bioRxiv, https://doi.org/10.1101/2023.07.06.547816.

[10] Gandon S., Day T., Metcalf C.J.E. and B.T. Grenfell. 2016. Forecasting epidemiological and evolutionary dynamics of infectious diseases. Trends in ecology & evolution, 31(10), pp.776-788. https://doi.org/10.1016/j.tree.2016.07.010

The paper titled "Celebrating the 20th Anniversary of the First Xanthomonas Genome Sequences – How Genomics Revolutionized Taxonomy Provided Insight into the Emergence of Pathogenic Bacteria Enabled New Fundamental Discoveries and Helped Developing Novel Control Measures – A Perspective from the French Network on Xanthomonads" by Ralf Koebnik et al. (2023) is an insightful contribution to the field of genomics and its application in understanding pathogenic bacteria, particularly Xanthomonas. This comprehensive review offers a unique perspective from the French Network on Xanthomonads, underscoring the significant advancements in taxonomy, pathogen emergence, and development of control strategies due to genomic research.

One of the paper's main strengths is its thorough exploration of how genomics has revolutionized our understanding of Xanthomonas and other pathogenic bacteria. It sheds light on the evolution and emergence of these pathogens, contributing significantly to the development of novel and effective control measures. The authors' detailed account of the historical progress and current state of genomics in this field highlights its pivotal role in guiding future research and practical applications in managing bacterial diseases.

Moreover, the paper emphasizes the importance of collaborative efforts and the sharing of knowledge within scientific networks, as exemplified by the French Network on Xanthomonas. This approach not only enriches the study but also serves as a model for future collaborative research endeavors.

In conclusion, the work of Koebnik et al. is a valuable resource for researchers, policymakers, and practitioners in the field of plant pathology and genomics. It not only provides a comprehensive overview of the advances in genomics related to Xanthomonas but also illustrates the broader impact of genomic studies in understanding and managing pathogenic bacteria.

References

Ralf Koebnik, Sophie Cesbron, Nicolas W. G. Chen, Marion Fischer-Le Saux, Mathilde Hutin, Marie-Agnès Jacques, Laurent D. Noël, Alvaro Perez-Quintero, Perrine Portier, Olivier Pruvost, Adrien Rieux, And Boris Szurek (2024) Celebrating the 20th anniversary of the first Xanthomonas genome gequences – How genomics revolutionized taxonomy, provided insight into the emergence of pathogenic bacteria, enabled new fundamental discoveries and helped developing novel control measures – A perspective from the French network on Xanthomonads. Zenodo ver. 3, peer-reviewed and recommended by Peer Community in Infections. https://doi.org/10.5281/zenodo.8223857

Mycobacterium bovis, also called M. tuberculosis var. bovis, is a bacterium belonging to the M. tuberculosis complex (i.e., MTBC) and which can cause through zoonotic transmission another form of human tuberculosis (Tb). It is above all the agent of bovine tuberculosis (i.e., bTb) which affects not only cattle (wild or farmed) but also a large diversity of other wild mammals worldwide. An increasing number of infected animal cases are being discovered in many regions of the world, thus raising the problem of tuberculosis transmission, including to humans, more complex than previously thought. Efforts have been made in terms of vaccination or culling of populations of host carrier species, such as the badger for example, however leading to consequences of greater dispersion of the infectious agent. M. bovis shows a more or less significant capacity to persist outside its hosts, particularly in the environment under certain abiotic and biotic conditions. This bacillus can be transmitted and spread in many ways, including through aerosol, mucus and sputum, urine and feces, by direct contact with infected animals, their dead bodies or rather via their excreta or by inhalation of aerosols, depending on the host species concerned.

In this paper, Calenge and his collaborators (Callenge et al. 2024) benefited from a national surveillance program on M. bovis cases in wild species, set up in 2011 in France, i.e., Sylvatub, for detecting and monitoring M. bovis infection in European badger (Meles meles) populations. Sylvatub is a participatory program involving both national and local stakeholder systems in order to determine changes in bTb infection levels in domestic and wild animal species. This original work had two aims: to describe spatial disease dynamics in the three clusters under scrutiny using a complex Bayesian model; and to develop indicators for the monitoring of the M. bovis infection by stakeholders and decision-makers of the program. This paper is timely and very comprehensive.

In this cogent study, the authors illustrate this point by using epidemiological surveillance to obtain large amounts of data (which is generally lacking in human epidemiology, but more dramatically lacking in animal epidemiology) and a highly sophisticated biostatistical analysis (Callenge et al. 2024). It is in itself a demonstration of the current capabilities of population dynamics applied to infectious disease situations, in this case animal, in the rapidly developing discipline of disease ecology and evolution. One of the aims of the study is to propose statistical models that can be used by the different stakeholders in charge, for instance, of wildlife conservation or the regional or State veterinary services to assess disease risk in the most affected regions.

References

Assel AKHMETOVA​, Jimena GUERRERO​, Paul McADAM, Liliana CM SALVADOR​, Joseph CRISPELL​, John LAVERY​, Eleanor PRESHO​, Rowland R KAO​, Roman BIEK​, Fraser MENZIES​, Nigel TRIMBLE​, Roland HARWOOD​, P Theo PEPLER, Katarina ORAVCOVA​, Jordon GRAHAM​, Robin SKUCE​, Louis DU PLESSIS​, Suzan THOMPSON​, Lorraine WRIGHT​, Andrew W BYRNE​, Adrian R ALLEN. 2023. Genomic epidemiology of Mycobacterium bovis infection in sympatric badger and cattle populations in Northern Ireland. Microbial Genomics 9: mgen001023. https://doi.org/10.1099/mgen.0.001023

Roman BIEK, Anthony O’HARE, David WRIGHT, Tom MALLON, Carl McCORMICK, Richard J ORTON, Stanley McDOWELL, Hannah TREWBY, Robin A SKUCE, Rowland R KAO. 2012. Whole genome sequencing reveals local transmission patterns of Mycobacterium bovis in sympatric cattle and badger populations. PLoS Pathogens 8: e1003008. https://doi.org/10.1371/journal.ppat.1003008

Clément CALENGE, Ariane PAYNE, Edouard REVEILLAUD, Céline RICHOMME, Sébastien GIRARD, Stephanie DESVAUX. 2024. Assessing the dynamics of Mycobacterium bovis infection in three French badger populations. bioRxiv, ver. 3 peer-reviewed and recommended by Peer Community In Infections. https://doi.org/10.1101/2023.05.31.543041

Marc CHOISY, Pejman ROHANI. 2006. Harvesting can increase severity of wildlife disease epidemics. Proceedings of the Royal Society, London, Ser. B 273: 2025-2034. https://doi.org/10.1098/rspb.2006.3554

Shannon C DUFFY, Sreenidhi SRINIVASAN, Megan A SCHILLING, Tod STUBER, Sarah N DANCHUK, Joy S MICHAEL, Manigandan VENKATESAN, Nitish BANSAL, Sushila MAAN, Naresh JINDAL, Deepika CHAUDHARY, Premanshu DANDAPAT, Robab KATANI, Shubhada CHOTHE, Maroudam VEERASAMI, Suelee ROBBE-AUSTERMAN, Nicholas JULEFF, Vivek KAPUR, Marcel A BEHR. 2020. Reconsidering Mycobacterium bovis as a proxy for zoonotic tuberculosis: a molecular epidemiological surveillance study. Lancet Microbe 1: e66-e73. https://doi.org/10.1016/S2666-5247(20)30038-0

Jean-François GUEGAN. 2019. The nature of ecology of infectious disease. The Lancet Infectious Diseases 19. https://doi.org/10.1016/s1473-3099(19)30529-8

Brandon H HAYES, Timothée VERGNE, Mathieu ANDRAUD, Nicolas ROSE. 2023. Mathematical modeling at the livestock-wildlife interface: scoping review of drivers of disease transmission between species. Frontiers in Veterinary Science 10: 1225446. https://doi.org/10.3389/fvets.2023.1225446

David KING, Tim ROPER, Douglas YOUNG, Mark EJ WOOLHOUSE, Dan COLLINS, Paul WOOD. 2007. Bovine tuberculosis in cattle and badgers. Report to Secretary of State about tuberculosis in cattle and badgers. London, UK. https://www.bovinetb.info/docs/RBCT_david_%20king_report.pdf  

Robert MM SMITH , Francis DROBNIEWSKI, Andrea GIBSON, John DE MONTAGUE, Margaret N LOGAN, David HUNT, Glyn HEWINSON, Roland L SALMON, Brian O’NEILL. 2004. Mycobacterium bovis Infection, United Kingdom. Emerging Infectious Diseases 10: 539-541. https://doi.org/10.3201/eid1003.020819