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The application of One Health concept to an outdoor problem-based learning activity for veterinary students

Putra TA, Hezmee MN, Farhana NB, Hassim HA, Intan-Shameha AR, Lokman IH, et al.

Vet World, 2016 Sep;9(9):955-959.
PMID: 27733795

The One Health (OH) approach, which seeks to bring together human and animal health, is particularly suited to the effective management of zoonotic diseases across both sectors. To overcome professional silos, OH needs to be taught at the undergraduate level. Here, we describe a problem-based learning activity using the OH approach that was conducted outdoors for 3(rd)-year veterinary students in Malaysia.

Matched MeSH terms: Zoonoses
Fulltext Using routine surveillance data to estimate the epidemic potential of emerging zoonoses: application to the emergence of US swine origin influenza A H3N2v virus

Cauchemez S, Epperson S, Biggerstaff M, Swerdlow D, Finelli L, Ferguson NM

PLoS Med, 2013;10(3):e1001399.
PMID: 23472057 DOI: 10.1371/journal.pmed.1001399

BACKGROUND: Prior to emergence in human populations, zoonoses such as SARS cause occasional infections in human populations exposed to reservoir species. The risk of widespread epidemics in humans can be assessed by monitoring the reproduction number R (average number of persons infected by a human case). However, until now, estimating R required detailed outbreak investigations of human clusters, for which resources and expertise are not always available. Additionally, existing methods do not correct for important selection and under-ascertainment biases. Here, we present simple estimation methods that overcome many of these limitations.
METHODS AND FINDINGS: Our approach is based on a parsimonious mathematical model of disease transmission and only requires data collected through routine surveillance and standard case investigations. We apply it to assess the transmissibility of swine-origin influenza A H3N2v-M virus in the US, Nipah virus in Malaysia and Bangladesh, and also present a non-zoonotic example (cholera in the Dominican Republic). Estimation is based on two simple summary statistics, the proportion infected by the natural reservoir among detected cases (G) and among the subset of the first detected cases in each cluster (F). If detection of a case does not affect detection of other cases from the same cluster, we find that R can be estimated by 1-G; otherwise R can be estimated by 1-F when the case detection rate is low. In more general cases, bounds on R can still be derived.
CONCLUSIONS: We have developed a simple approach with limited data requirements that enables robust assessment of the risks posed by emerging zoonoses. We illustrate this by deriving transmissibility estimates for the H3N2v-M virus, an important step in evaluating the possible pandemic threat posed by this virus. Please see later in the article for the Editors' Summary.

Matched MeSH terms: Zoonoses/epidemiology*; Zoonoses/transmission
Bats and emerging zoonoses: henipaviruses and SARS

Field HE

Zoonoses Public Health, 2009 Aug;56(6-7):278-84.
PMID: 19497090 DOI: 10.1111/j.1863-2378.2008.01218.x

Nearly 75% of all emerging infectious diseases (EIDs) that impact or threaten human health are zoonotic. The majority have spilled from wildlife reservoirs, either directly to humans or via domestic animals. The emergence of many can be attributed to predisposing factors such as global travel, trade, agricultural expansion, deforestation/habitat fragmentation, and urbanization; such factors increase the interface and/or the rate of contact between human, domestic animal, and wildlife populations, thereby creating increased opportunities for spillover events to occur. Infectious disease emergence can be regarded as primarily an ecological process. The epidemiological investigation of EIDs associated with wildlife requires a trans-disciplinary approach that includes an understanding of the ecology of the wildlife species, and an understanding of human behaviours that increase risk of exposure. Investigations of the emergence of Nipah virus in Malaysia in 1999 and severe acute respiratory syndrome (SARS) in China in 2003 provide useful case studies. The emergence of Nipah virus was associated with the increased size and density of commercial pig farms and their encroachment into forested areas. The movement of pigs for sale and slaughter in turn led to the rapid spread of infection to southern peninsular Malaysia, where the high-density, largely urban pig populations facilitated transmission to humans. Identifying the factors associated with the emergence of SARS in southern China requires an understanding of the ecology of infection both in the natural reservoir and in secondary market reservoir species. A necessary extension of understanding the ecology of the reservoir is an understanding of the trade, and of the social and cultural context of wildlife consumption. Emerging infectious diseases originating from wildlife populations will continue to threaten public health. Mitigating and managing the risk requires an appreciation of the connectedness between human, livestock and wildlife health, and of the factors and processes that disrupt the balance.

Matched MeSH terms: Zoonoses*
Emerging encephalitogenic viruses: lyssaviruses and henipaviruses transmitted by frugivorous bats

Mackenzie JS, Field HE

Arch. Virol. Suppl., 2004.
PMID: 15119765

Three newly recognized encephalitogenic zoonotic viruses spread from fruit bats of the genus Pteropus (order Chiroptera, suborder Megachiroptera) have been recognised over the past decade. These are: Hendra virus, formerly named equine morbillivirus, which was responsible for an outbreak of disease in horses and humans in Brisbane, Australia, in 1994; Australian bat lyssavirus, the cause of a severe acute encephalitis, in 1996; and Nipah virus, the cause of a major outbreak of encephalitis and pulmonary disease in domestic pigs and people in peninsula Malaysia in 1999. Hendra and Nipah viruses have been shown to be the first two members of a new genus, Henipavirus, in the family Paramyxoviridae, subfamily Paramyxovirinae, whereas Australian bat lyssavirus is closely related antigenically to classical rabies virus in the genus Lyssavirus, family Rhabdoviridae, although it can be distinguished on genetic grounds. Hendra and Nipah viruses have neurological and pneumonic tropisms. The first humans and equids with Hendra virus infections died from acute respiratory disease, whereas the second human patient died from an encephalitis. With Nipah virus, the predominant clinical syndrome in humans was encephalitic rather than respiratory, whereas in pigs, the infection was characterised by acute fever with respiratory involvement with or without neurological signs. Two human infections with Australian bat lyssavirus have been reported, the clinical signs of which were consistent with classical rabies infection and included a diffuse, non-suppurative encephalitis. Many important questions remain to be answered regarding modes of transmission, pathogenesis, and geographic range of these viruses.

Matched MeSH terms: Zoonoses
Fulltext Association of rodent-borne Leptospira spp. with urban environments in Malaysian Borneo

Blasdell KR, Morand S, Perera D, Firth C

PLoS Negl Trop Dis, 2019 02;13(2):e0007141.
PMID: 30811387 DOI: 10.1371/journal.pntd.0007141

Although leptospirosis is traditionally considered a disease of rural, agricultural and flooded environments, Leptospira spp. are found in a range of habitats and infect numerous host species, with rodents among the most significant reservoirs and vectors. To explore the local ecology of Leptospira spp. in a city experiencing rapid urbanization, we assessed Leptospira prevalence in rodents from three locations in Malaysian Borneo with differing levels of anthropogenic influence: 1) high but stable influence (urban); 2) moderate yet increasing (developing); and 3) low (rural). A total of 116 urban, 122 developing and 78 rural rodents were sampled, with the majority of individuals assigned to either the Rattus rattus lineage R3 (n = 165) or Sundamys muelleri (n = 100). Leptospira spp. DNA was detected in 31.6% of all rodents, with more urban rodents positive (44.8%), than developing (32.0%) or rural rodents (28.1%), and these differences were statistically significant. The majority of positive samples were identified by sequence comparison to belong to known human pathogens L. interrogans (n = 57) and L. borgpetersenii (n = 38). Statistical analyses revealed that both Leptospira species occurred more commonly at sites with higher anthropogenic influence, particularly those with a combination of commercial and residential activity, while L. interrogans infection was also associated with low forest cover, and L. borgpetersenii was more likely to be identified at sites without natural bodies of water. This study suggests that some features associated with urbanization may promote the circulation of Leptospira spp., resulting in a potential public health risk in cities that may be substantially underestimated.

Matched MeSH terms: Zoonoses/microbiology; Zoonoses/epidemiology*
Melioidosis: a disease of rodents communiable to man

Stanton AT, Fletcher W

Malayan Medical Journal, 1926;1:26-30.

Matched MeSH terms: Zoonoses
Fulltext Natural Human Infections With Plasmodium cynomolgi and Other Malaria Species in an Elimination Setting in Sabah, Malaysia

Grignard L, Shah S, Chua TH, William T, Drakeley CJ, Fornace KM

J Infect Dis, 2019 11 06;220(12):1946-1949.
PMID: 31418017 DOI: 10.1093/infdis/jiz397

To determine the presence and species composition of malaria infections, we screened a subset of samples collected during a cross-sectional survey in Northern Sabah, Malaysia using highly sensitive molecular techniques. Results identified 54 asymptomatic submicroscopic malaria infections, including a large cluster of Plasmodium falciparum and 3 P. knowlesi infections. We additionally identified 2 monoinfections with the zoonotic malaria Plasmodium cynomolgi, both in individuals reporting no history of forest activities or contact with macaques. Results highlight the need for improved surveillance strategies to detect these infections and determine public health impacts.

Matched MeSH terms: Zoonoses
Fulltext Study of Ebola virus outbreak dynamics, impact of vaccination and other preventive measures on transmission control

Che Ismail Che Noh, Fox, Anthony William

Borneo Journal of Medical Sciences, 2018;12(2):9-18.
MyJurnal

Ebola virus disease (EVD) is an emerging and remerging zoonosis associated with high fatality rate, mainly caused by the Zaire Ebola virus (ZEBOV) and Sudan Ebola virus (SEBOV) strains. Approximately 20 epidemics of EVD have been documented mainly in Central African countries since 1976. Currently, there are no therapeutics agents and vaccines yet approved for EVD. However, several promising therapeutics and vaccines candidates are actively undergoing various phase of clinical development. This study aims to study the EVD dynamics and evaluate the potential impacts of vaccines and other preventive measures on EVD transmission control and significance of medical intervention on outcome of the disease. An initial branch chain model of EVD dynamics was built based on data obtained from previous study. Different epidemiological scenarios for EVD with impacts of intervention were simulated using Berkeley-Madonna Version 8.3.18 software. Every reduction in the exposure rate of EBV infection by 10% produces two- to five-fold improvement in protection against EVD. Transmission control is optimum when the rate of exposure to EBV infection is reduced below 1%. Optimal control of EVD transmission can be achieved through strategic implementation of successful vaccination programme, and other preventive measures as well as rapid delivery of supportive medical care.

Matched MeSH terms: Zoonoses
The rabies situation in Far East Asia

Fu ZF

Dev Biol (Basel), 2008;131:55-61.
PMID: 18634466

This study evaluated rabies epidemiology in Far EastAsia. Questionnaires were sent by the OIE to Far East Asian countries and eight questionnaires were returned. Data were collected from these returns, as well as from recent publications, to gather information regarding rabies epidemiology in these countries. More than 29,000 human deaths were reported in 2006 in Far East Asia, representing more than 50% of all human rabies cases around the globe. There are only a few countries or regions from which no human rabies was reported in 2006 such as Japan, Singapore, South Korea, Malaysia, Hong Kong, and Taiwan. In many of these rabies endemic countries, the number of human rabies cases has not changed much during the past decade. The only country with a steady decline is Thailand, where the number of cases has decreased from around 200 to about 20 cases per year. The most dramatic changes were observed in China. Human rabies cases declined from around 5,000 cases per year in the 1980s to about 160 in the mid-1990s. However, these trends have since been reversed. A steady increase has been reported over the past 10 years with more than 3,200 cases reported in 2006. Although there are many factors that contribute to the epidemic or endemic nature of rabies in these countries, the single most important factor is the failure to immunize domestic dogs, which transmit rabies to humans. Dog vaccination is at or below 5% in many of these countries, and cannot stop the transmission of rabies from dogs to dogs, thus to humans. It is thus most importantforthese countries to initiate mass vaccination campaigns in dog populations in order to stop the occurrence of human rabies in Far East Asia.

Matched MeSH terms: Zoonoses
Toxocara malaysiensis infection in domestic cats in Vietnam--An emerging zoonotic issue?

Le TH, Anh NT, Nguyen KT, Nguyen NT, Thuy do TT, Gasser RB

Infect Genet Evol, 2016 Jan;37:94-8.
PMID: 26584512 DOI: 10.1016/j.meegid.2015.11.009

Toxocara canis of canids is a parasitic nematode (ascaridoid) that infects humans and other hosts, causing different forms of toxocariasis. This species of Toxocara appears to be the most important cause of human disease, likely followed by Toxocara cati from felids. Although some studies from Malaysia and China have shown that cats can harbor another congener, T. malaysiensis, no information is available about this parasite for other countries. Moreover, the zoonotic potential of this parasite is unknown at this point. In the present study, we conducted the first investigation of domestic dogs and cats for Toxocara in Vietnam using molecular tools. Toxocara malaysiensis was identified as a common ascaridoid of domestic cats (in the absence of T. cati), and T. canis was commonly found in dogs. Together with findings from previous studies, the present results emphasize the need to explore the significance and zoonotic potential of T. malaysiensis in Vietnam and other countries where this parasite is endemic and prevalent in cats.

Matched MeSH terms: Zoonoses/parasitology
Fulltext Use of Single-Injection Recombinant Vesicular Stomatitis Virus Vaccine to Protect Nonhuman Primates Against Lethal Nipah Virus Disease

Mire CE, Geisbert JB, Agans KN, Versteeg KM, Deer DJ, Satterfield BA, et al.

Emerg Infect Dis, 2019 Jun;25(6):1144-1152.
PMID: 31107231 DOI: 10.3201/eid2506.181620

Nipah virus (NiV) is a zoonotic pathogen that causes high case-fatality rates (CFRs) in humans. Two NiV strains have caused outbreaks: the Malaysia strain (NiVM), discovered in 1998-1999 in Malaysia and Singapore (≈40% CFR); and the Bangladesh strain (NiVB), discovered in Bangladesh and India in 2001 (≈80% CFR). Recently, NiVB in African green monkeys resulted in a more severe and lethal disease than NiVM. No NiV vaccines or treatments are licensed for human use. We assessed replication-restricted single-injection recombinant vesicular stomatitis vaccine NiV vaccine vectors expressing the NiV glycoproteins against NiVB challenge in African green monkeys. All vaccinated animals survived to the study endpoint without signs of NiV disease; all showed development of NiV F Ig, NiV G IgG, or both, as well as neutralizing antibody titers. These data show protective efficacy against a stringent and relevant NiVB model of human infection.

Matched MeSH terms: Zoonoses*
Fulltext A retrospective study of bovine tuberculosis at the municipal abattoir of Bauchi State, Northeastern Nigeria

Jajere SM, Atsanda NN, Bitrus AA, Hamisu TM, Goni MD

Vet World, 2018 May;11(5):598-605.
PMID: 29915497 DOI: 10.14202/vetworld.2018.598-605

Background and Aim: Bovine tuberculosis (bTB) still remains a major zoonotic bacterial disease affecting livestock and humans worldwide. The disease remains a poorly managed tropical disease in most developing countries of the world; where in addition to productivity losses and significance in international trade, it posed a major public health threat to both humans and animals. A retrospective study was designed to investigate the occurrence of bTB lesions at Bauchi municipal abattoir.
Materials and Methods: The study utilized abattoir records spanning a period of 10 years (2004-2013). The records indicated that a total of 1,08,638 heads of cattle comprising n = 56,070 males and n = 52,570 females were slaughtered at the municipal abattoir during the study period.
Result: Of these heads, n = 1230 (1.13%) (95% confidence interval [CI]: 1.07, 1.19) had tuberculous lesions. The annual occurrence during the study period varied significantly (p<0.001) from 0.53% (95% CI: 0.40, 0.67) to 1.87% (95% CI: 1.66, 2.10) in 2010 and 2012, respectively. Females had a significantly higher (p<0.001) prevalence of 2.10% (95% CI: 1.98, 2.23) compared with the males 0.23% (95% CI: 0.19, 0.27). The distribution of suspected gross bTB lesions in different organs showed 11.87% in the lungs, 5.93% in the liver, 1.14% in the heart, and 0.49% accounted for generalized bTB. However, none was observed on the lymph nodes and intestines.
Conclusion: It can be concluded that bTB persists in Bauchi State with annual variations during the study period. This study highlights the importance of meat inspection as an important tool for detecting the presence of bTB lesions.

Matched MeSH terms: Zoonoses
Fulltext Potential for Person-to-Person Transmission of Henipaviruses: A Systematic Review of the Literature

Hegde ST, Lee KH, Styczynski A, Jones FK, Gomes I, Das P, et al.

J Infect Dis, 2024 Mar 14;229(3):733-742.
PMID: 37925626 DOI: 10.1093/infdis/jiad467

Nipah virus Bangladesh (NiVB) is a bat-borne zoonosis transmitted between people through the respiratory route. The risk posed by related henipaviruses, including Hendra virus (HeV) and Nipah virus Malaysia (NiVM), is less clear. We conducted a broad search of the literature encompassing both human infections and animal models to synthesize evidence about potential for person-to-person spread. More than 600 human infections have been reported in the literature, but information on viral shedding was only available for 40 case-patients. There is substantial evidence demonstrating person-to-person transmission of NiVB, and some evidence for NiVM. Less direct evidence is available about the risk for person-to-person transmission of HeV, but animals infected with HeV shed more virus in the respiratory tract than those infected with NiVM, suggesting potential for transmission. As the group of known henipaviruses continues to grow, shared protocols for conducting and reporting from human investigations and animal experiments are urgently needed.

Matched MeSH terms: Zoonoses/transmission
Managing emerging diseases borne by fruit bats (flying foxes), with particular reference to henipaviruses and Australian bat lyssavirus

Mackenzie JS, Field HE, Guyatt KJ

J Appl Microbiol, 2003;94 Suppl:59S-69S.
PMID: 12675937

Since 1994, a number of novel viruses have been described from bats in Australia and Malaysia, particularly from fruit bats belonging to the genus Pteropus (flying foxes), and it is probable that related viruses will be found in other countries across the geographical range of other members of the genus. These viruses include Hendra and Nipah viruses, members of a new genus, Henipaviruses, within the family Paramyxoviridae; Menangle and Tioman viruses, new members of the Rubulavirus genus within the Paramyxoviridae; and Australian bat lyssavirus (ABLV), a member of the Lyssavirus genus in the family Rhabdoviridae. All but Tioman virus are known to be associated with human and/or livestock diseases. The isolation, disease associations and biological properties of the viruses are described, and are used as the basis for developing management strategies for disease prevention or control. These strategies are directed largely at disease minimization through good farm management practices, reducing the potential for exposure to flying foxes, and better disease recognition and diagnosis, and for ABLV specifically, the use of rabies vaccine for pre- and post-exposure prophylaxis. Finally, an intriguing and long-term strategy is that of wildlife immunization through plant-derived vaccination.

Matched MeSH terms: Zoonoses*
Fulltext Knowledge, attitude and practice on leptospirosis among undergraduate students in University Putra Malaysia

Siti Maryam Abu Bakar, Haliza Abdul Rahman

Malaysian Journal of Medicine and Health Sciences, 2018;14(102):0-0.
MyJurnal

Leptospirosis is an infectious and zoonotic disease caused by pathogenic bacteria called leptospires which can be transmitted through the exposure to the urine or excretion of infected animals, and also water or soil that being contaminated with secretion of the infected animals. Leptospirosis remains a concern in Malaysia, as the number of cases had steadily increased. This study aims to determine the knowledge, attitude and practice (KAP) among final year students of selected programmes in Universiti Putra Malaysia (UPM). Methods: A cross sectional study was conducted among students of Environmental and Occupational Health (ENVOCH) (57 students), Nursing (22 students) and Veterinary Medicine (97 students). Thus, the total sample sizes were 170, however the response rate were 81.76%. Questionnaire was used as the study instrumentation. Results: There was a significant association between race and knowledge, also gender and attitude with p

Matched MeSH terms: Zoonoses
Fulltext High diversity of picornaviruses in rats from different continents revealed by deep sequencing

Hansen TA, Mollerup S, Nguyen NP, White NE, Coghlan M, Alquezar-Planas DE, et al.

Emerg Microbes Infect, 2016 Aug 17;5(8):e90.
PMID: 27530749 DOI: 10.1038/emi.2016.90

Outbreaks of zoonotic diseases in humans and livestock are not uncommon, and an important component in containment of such emerging viral diseases is rapid and reliable diagnostics. Such methods are often PCR-based and hence require the availability of sequence data from the pathogen. Rattus norvegicus (R. norvegicus) is a known reservoir for important zoonotic pathogens. Transmission may be direct via contact with the animal, for example, through exposure to its faecal matter, or indirectly mediated by arthropod vectors. Here we investigated the viral content in rat faecal matter (n=29) collected from two continents by analyzing 2.2 billion next-generation sequencing reads derived from both DNA and RNA. Among other virus families, we found sequences from members of the Picornaviridae to be abundant in the microbiome of all the samples. Here we describe the diversity of the picornavirus-like contigs including near-full-length genomes closely related to the Boone cardiovirus and Theiler's encephalomyelitis virus. From this study, we conclude that picornaviruses within R. norvegicus are more diverse than previously recognized. The virome of R. norvegicus should be investigated further to assess the full potential for zoonotic virus transmission.

Matched MeSH terms: Zoonoses
Case-control study on risk factors associated with Brucella melitensis in goat farms in Peninsular Malaysia

Bamaiyi PH, Hassan L, Khairani-Bejo S, ZainalAbidin M, Ramlan M, Krishnan N, et al.

Trop Anim Health Prod, 2014 Jun;46(5):739-45.
PMID: 24633657 DOI: 10.1007/s11250-014-0557-x

Caprine brucellosis is a bacterial zoonotic infection affecting goats especially in developing countries all over the world. In Malaysia, the risk factors associated with this infection in farms have not been studied. A case-control study was carried out in goat farms in four states of Malaysia to elucidate the risk factors associated with the infection on the farms using structured questionnaires and face-to-face interviews. Results indicate that the introduction of new animals (OR = 5.25; 90 % CI = 1.46, 18.88), younger age category of farms (OR = 5.53; 90 % CI = 1.09, 21.66), and farms with single breed of goats (OR = 8.50; 90 % CI = 1.27, 41.97) were significant risk factors for brucellosis. In order to control brucellosis or possibly eradicate it in goat farms, these factors need to be dealt with. Enforcing stringent importation protocols or complete ban of goat importation from brucellosis endemic countries will help reduce risk of introducing new infection into the country.

Matched MeSH terms: Zoonoses
Fulltext Effectiveness of antibiotic prophylaxis for leptospirosis among adults: a systematic review

Muhammad Aklil, A.R., Aznida, M.Z., Azman A., Muhammad Haneef, A., Nik Him, N.A.S., Syed Sharizman, S.A.R., et al.

Malaysian Journal of Applied Sciences, 2018;3(2):46-56.
MyJurnal

Leptospirosis is one of the most widespread re-emerging zoonoses in the world. Malaysia is known to
be an endemic country for human leptospirosis, with a case fatality rate of 2.11%, and an average annual
incidence rate of 7.80 cases per 100,000 individuals. This systematic review is conducted to determine
the effectiveness of antibiotic prophylaxis for leptospirosis among the adult populations who are highly
at risk of getting infected. A systematic search was performed for the relevant titles, abstracts and
keywords on PubMed, Scopus, Cochrane and Google Scholar from inception to November 2017 based
on the PICO strategy; which returned 126 studies. Screening of abstracts had shortlisted 19 studies and
data extraction was conducted for 8 studies which had been accepted after review of the full text. For
the evaluation of antibiotics prophylaxis effectiveness against leptospirosis, only trials and cohort studies
with risk ratio (RR) were selected. The articles were analyzed from the viewpoint of the dosage, adverse
effects, study settings and effectiveness of the antibiotic prophylaxis. Using fixed effects model, pooled
RR showed protective association between antibiotic prophylaxis use against the incidence of
leptospirosis (RR = 0.31; 95% CI: 0.20, 0.48). Antibiotic prophylaxis for leptospirosis had been shown
to be effective in preventing the incidence of the disease among high-risk populations and carries
minimal adverse effects. It is recommended that the practice of antibiotic prophylaxis for leptospirosis is
included in the standard protocol for leptospirosis prevention among people at high-risk, including
disaster response teams and patrons of eco-sports tourism activities; with the drug of choice being
doxycycline, either as a single 200 mg dose or weekly dose of 200 mg for the duration of exposure,
based on the setting, duration of event and resources available.

Matched MeSH terms: Zoonoses
Zoonoses as a study in ecology

Heisch RB

Br Med J, 1956;2:669.
DOI: 10.1136/bmj.2.4994.669

The zoonoses, which are defined as infections of man naturally acquired from other vertebrates, are treated as a problem in ecology. This entails studying the interrelation between man, animals, a causative organism, the environment, and sometimes arthropods. Such an approach is holistic or synecological—wholes being regarded as more important than parts. Holism is a dynamic not a static conception. The evolution of the zoonoses is discussed, particularly in relation to plague, relapsing fever, and leishmaniasis. The most important reservoirs of zoonoses and other parasitic infections are usually resistant or relatively insusceptible animals rather than highly susceptible ones. Plague and Chagas's disease illustrate this. Resistant and unduly susceptible animals occupy different “niches“ in nature. By “niche“ is meant the place of an animal in its biotic environment. Zoonoses often have a “focal distribution“ in nature. Thus wild rodents infected with plague may occur in “ pockets,” and the vector mites of scrub typhus congregate in “typhus islands.” An unstable environment often favours the transference of zoonoses to man and animals. Examples are the plague-infected plain of Rongai, in Kenya, the typhus-infected forest clearings in Malaya, and the yellow-fever infected forest edges in Uganda. Ecologically unstable areas are termed “ ecotones.” Zoonoses can also be transmitted in or near relatively stable sites such as huts, rodent burrows, caves, and termite hills. These are known as “habitat niches.” Animals and arthropods in a community are linked by food, and the importance of what are known as “food chains“ and “food cycles“ is discussed in relation to the transference of zoonotic infections from one host to another. Reference is also made to the fluctuations in numbers of various animals in nature, and how this affects the incidence of zoonotic disease. Certain highly susceptible rodents are periodically decimated by plague; this breaks the link with man, and human infections cease for the time being. © 1956, British Medical Journal Publishing Group. All rights reserved.

Matched MeSH terms: Zoonoses
Fulltext Agricultural intensification, priming for persistence and the emergence of Nipah virus: a lethal bat-borne zoonosis

Pulliam JR, Epstein JH, Dushoff J, Rahman SA, Bunning M, Jamaluddin AA, et al.

J R Soc Interface, 2012 Jan 7;9(66):89-101.
PMID: 21632614 DOI: 10.1098/rsif.2011.0223

Emerging zoonoses threaten global health, yet the processes by which they emerge are complex and poorly understood. Nipah virus (NiV) is an important threat owing to its broad host and geographical range, high case fatality, potential for human-to-human transmission and lack of effective prevention or therapies. Here, we investigate the origin of the first identified outbreak of NiV encephalitis in Malaysia and Singapore. We analyse data on livestock production from the index site (a commercial pig farm in Malaysia) prior to and during the outbreak, on Malaysian agricultural production, and from surveys of NiV's wildlife reservoir (flying foxes). Our analyses suggest that repeated introduction of NiV from wildlife changed infection dynamics in pigs. Initial viral introduction produced an explosive epizootic that drove itself to extinction but primed the population for enzootic persistence upon reintroduction of the virus. The resultant within-farm persistence permitted regional spread and increased the number of human infections. This study refutes an earlier hypothesis that anomalous El Niño Southern Oscillation-related climatic conditions drove emergence and suggests that priming for persistence drove the emergence of a novel zoonotic pathogen. Thus, we provide empirical evidence for a causative mechanism previously proposed as a precursor to widespread infection with H5N1 avian influenza and other emerging pathogens.

Matched MeSH terms: Zoonoses/epidemiology*; Zoonoses/transmission; Zoonoses/virology

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