Emerging zoonotic viruses

Emerging infectious diseases poses a great future threat, not only to humans but also to domestic animals and wildlife. Even though the majority of these infections only cause minor health problems, the relatively recent emergence of HIV clearly illustrates that the next major human pandemic may surface at any time. Regardless of what the name indicates, most emerging human pathogens are not believed to be recently evolved, but to have existed previously in the natural environment. Most emerging pathogens are zoonotic, i.e. able to infect animals besides humans. Viruses are significantly overrepresented, which is thought to be due to the general difficulties in treating and controlling viral diseases, as well as the substantial amount of genetic diversity that viruses exhibits. Even though there is no clear association between the classification of a virus as zoonotic and its’ risk of emergence, many emerging viruses have been shown to be zoonotic or have a zoonotic history. Therefore it is probably accurate to conclude that zoonotic viruses constitute a significant risk for future emergence events. Since the majority of emerging pathogens are zoonotic, the process of cross-species transmission of a microbe from its reservoir to humans is likely to play a central role. It is probable that humans are exposed to unfamiliar pathogens regularly, but that only a few of them will possess the required genetic features to successfully cause human infection. A fraction of these pathogens may go on to acquire the ability to transmit between humans, whereof an additional few may evolve to transmit at a rate that enables major epidemics. When emergence occurs, it appears to disproportionately often happen in areas that are affected by anthropogenic activities. Some of these activities are believed to act by augmenting exposure of humans to novel pathogens, reservoirs or vectors, others by enhancing disease transmission. In order to be prepared for future emergence events, there is a great need for additional research on numerous aspects of the emergence process. Also, given the complexity and multifactorial nature of disease emergence, a multidisciplinary and internationally conjunctive approach is often advised.Infektiösa patogener som påvisats i en population för första gången, alternativt uppvisar en ökning i incidens eller geografisk spridning, utgör ett allvarligt framtida hot för såväl människor som djur. Majoriteten av dessa patogener orsakar endast mindre hälsoproblem, men risken att nästa stora pandemi kan vara nära i antågande får ej försummas. Detta illustreras tydligt av HIV, som på relativt kort tid har etablerat sig som en av världens mest fruktade infektiösa agens. Patogenerna av denna typ antas sällan vara nyutvecklade, utan förmodas oftast ha förekommit tidigare i naturen. De allra flesta är zoonotiska och därmed kapabla att infektera andra arter utöver människa. Virus är överrepresenterade, vilket dels antas bero på svårigheterna i att behandla och kontrollera virala sjukdomar, såväl som den enorma genetiska mångfald som virus uppvisar. Än så länge har ingen tydlig association kunnat påvisas mellan ett virus zoonotiska status och dess benägenhet att nyinfektera människor. Men eftersom en betydande andel trots allt innehar förmågan att infektera djur utöver människa, eller har haft historiskt, är det sannolikt att zoonotiska virus är en av de patogengrupper som utgör störst risk för framtiden. Eftersom många av de patogener som påvisats i humana populationer för första gången, alternativt uppvisar en ökning i incidens eller geografisk spridning, är sprungna ur djurpopulationer, kan överföringen av mikroorganismer från djur till människa antas spela en central roll. Troligen exponeras människan ständigt för främmande patogener, men endast ett mindre antal av dessa kommer att inneha de rätta genetiska förutsättningarna för att kunna orsaka mänsklig infektion. Av dessa är det troligen bara ett fåtal som kommer att utveckla förmågan att spridas mellan människor, varav endast en fraktion lyckas förfina detta till den grad att de kan skapa humana pandemier. Denna övergång från djurinfektion till human pandemi sker anmärkningsvärt ofta i områden som står under antropogen påverkan. Vissa av dessa aktiviteter förmodas verka genom att utöka exponeringen av människor för nya patogener, dess reservoarer eller vektorer, andra genom att underlätta spridning i populationen. För att mänskligheten i framtiden ska kunna förhålla sig till hotet som dessa infektiösa patogener utgör, finns det stora behov av forskning inom flera områden. Eftersom processen är komplex och multifaktoriell är en multidisciplinär och internationellt samordnad angreppsmetod ofta att rekommendera

Prevalence and risk factors for BVDV in goats and cattle in and around Gaborone, Botswana

SUMMARY Bovine Viral Diarrhoea Virus (BVDV) is a cause of severe deterioration in animal health as well as grave economic losses globally. Infection is often inapparent but the virus can also cause respiratory signs, diarrhoea, pyrexia, decreased production, immunosuppression and reproductive problems such as increased calving intervals and abortions. Also, when naive dams in early pregnancy are infected, before the development of fetal immune competence, the fetus is at risk of developing persistent infection. These persistently infected individuals (PI) are of particular epidemiologic interest since they shed virus in large concentrations in all their bodily secretions throughout their life. Risk factors for disease transmission include, but are not limited to, herd size, animal trade and grazing on communal pastures. For goats, contact with cattle is a significant risk factor. Several prevalence studies have been conducted on the African continent, but in the country of Botswana, the occurrence is largely unknown. Because of this, blood samples were obtained from 100 goats owned by 11 smallholder farmers, in three different villages just outside of Gaborone. Besides this, 361 blood samples from cattle collected as part of another study were analysed. The detected antibody prevalence was 0% in goats and 53.5% in cattle. In dairy cattle, the seroprevalence was 49.7% and in beef cattle 56.7%, but this difference was not statistically significant. The prevalence of virus in cattle was 0.27% on Ag-ELISA and PCR performed in Botswana, and 0.83% on PCR performed in Sweden. The viraemic animals all originated in the two herds with the highest prevalences (88.1% and 97.9% respectively). Finally, PCR analysis was performed and a short sequence of the genome of two of the detected viruses were sequenced, and found to belong to the BVDV-1a genotype. The goat farmers were also subjected to a short interview regarding risk factors for BVDV transmission, as well as the general health status in their herd. All farmers allowed their animals to graze on communal pastures, and 64% reported to also keep cattle in close proximity to their goats. Also, 18% answered that they keep sheep and goats together in the same kraal (i.e. enclosure) during the night. Approximately 55% responded that they occasionally saw wildlife ruminants in the area where their goats were kept. However, only 18% purchased goats from other farmers as the majority relied solely on raising their own kidlings. The most common health problem described was abortion, which 91% occasionally struggled with. Besides this, 64% also reported problems with diarrhoea, 36% with coughing and 18% with ocular and nasal discharge. Last but not least, all farmers stated that they depend on their goats for food and cash income and that it would affect them greatly if their animals would fall sick or die in large numbers.SAMMANFATTNING Bovint Virus Diarré Virus (BVDV) är en global orsak till nedsatt djurhälsa samt ekonomiska förluster. Infektionen är ofta subklinisk men viruset kan också orsaka respiratoriska symptom, diarré, pyrexi, nedsatt produktion, nedsatt immunförsvar samt reproduktiva störningar såsom förlängda kalvningsintervall och aborter. När seronegativa hondjur infekteras under tidig dräktighet, innan fostret bildat immunokompetens, finns en risk att avkomman utvecklar persistent infektion (PI). Dessa djur är av särskilt epidemiologiskt intresse då de utsöndrar virus i höga koncentrationer i samtliga kroppsvätskor under hela deras liv. Riskfaktorer för virusspridning är exempelvis stor besättningsstorlek och hög djurdensitet. Även driftrutiner såsom djurhandel och utnyttjande av gemensamma betesmarker inverkar. För getter är kontakt med nötkreatur en riskfaktor. Ett flertal prevalensstudier avseende BVDV har utförts på den afrikanska kontinenten, men i Botswana är förekomsten i stort sett okänd. På grund av detta utfördes blodprovstagning på totalt 100 getter, vilka ägdes av 11 småbrukande bönder hemmahörande i tre olika byar utanför Gaborone. Utöver dessa analyserades även 361 blodprover från nötkreatur, vilka tagits som en del av ett annat forskningsprojekt. Antikroppsprevalensen var 0% för get och 53,5 % för nötkreatur. För mjölkkor var seroprevalensen 49,7% och för köttkor 56,7%, men denna skillnad var ej statistiskt signifikant. Prevalensen av BVD-virus, baserat på resultat från Ag-ELISA och PCR, var 0,27%. När PCR:en senare upprepades i Sverige blev resultatet 0,83%. Samtliga viraemiska djur härstammade från de två besättningar med högst seroprevalens (88,1% resp 97,9%). Slutligen gjordes en PCR analys och en del av genomet sekvenserades för två av de detekterade virusen, och befanns tillhöra genotypen BVDV-1a. Småbrukarna fick även i en kort intervju svara på frågor avseende riskfaktorer för spridning och smitta av BVDV samt den generella hälsostatusen i deras besättning. Intervjuerna påvisade flertalet riskfaktorer för virusspridning. Samtliga av bönderna lät sina djur beta fritt på allmänna betesmarker och 64% angav att de höll nötkreatur i nära anslutning till getterna. Ungefär 18% höll getter och får i samma inhägnad nattetid. Cirka 55% angav att de då och då såg vilda idisslare i sitt närområde. Endast 18% köpte getter från andra bönder, då majoriteten enbart använde sig av egen uppfödning av killingar. Det vanligaste hälsoproblemet var aborter, vilket 91% angav att de hade problem med till och från. Av bönderna hade även 64% bekymmer med diarré, 36% med hosta och 18% med ögon- och nosflöde. Samtliga angav att de är väldigt beroende av deras getter för föda och inkomst, och att ett större sjukdomsutbrott med dödsfall skulle ha en allvarlig påverkan på deras livssituation

Herd health and reproductive management associated with lamb weight gain and mortality in sub-Saharan drylands-a case from Ethiopia.

Sheep are important for food and livelihood security in sub-Saharan Africa, and maximizing lamb weight gain while minimizing mortality is essential to improve production. Using the Menz sheep breeding villages of Amhara region in Ethiopia as a case study, the weight gain and mortality rate of 208 lambs were monitored during their first 5 months of life. The study was conducted in intervention and control villages, where the intervention villages were part of community-based breeding programmes and had participated in various projects aiming to improve sheep production and management. Multivariable linear regression analysis was conducted to detect associations between weight gain from birth to 1 month, and birth to 5 months, and different lamb and ewe characteristics, farmer education, application of management routines, and presence of village level sheep management interventions. In general, lambs from intervention villages, without certain signs of diseases, whose mothers were 2 years or older, had a body condition score of more than 2 on a 5-point scale, and who originated from flocks where disease prevention strategies had been implemented, had gained more weight. Overall lamb mortality was 6.8% with most deaths occurring before 1 month of age. This study highlights that health interventions in ewes improve lamb survival and weight gain and that the care of lambs during the first month of life is crucial for overall herd productivity

Herd health and reproductive management associated with lamb weight gain and mortality in sub-Saharan drylands-a case from Ethiopia

Sheep are important for food and livelihood security in sub-Saharan Africa, and maximizing lamb weight gain while minimizing mortality is essential to improve production. Using the Menz sheep breeding villages of Amhara region in Ethiopia as a case study, the weight gain and mortality rate of 208 lambs were monitored during their first 5 months of life. The study was conducted in intervention and control villages, where the intervention villages were part of community-based breeding programmes and had participated in various projects aiming to improve sheep production and management. Multivariable linear regression analysis was conducted to detect associations between weight gain from birth to 1 month, and birth to 5 months, and different lamb and ewe characteristics, farmer education, application of management routines, and presence of village level sheep management interventions. In general, lambs from intervention villages, without certain signs of diseases, whose mothers were 2 years or older, had a body condition score of more than 2 on a 5-point scale, and who originated from flocks where disease prevention strategies had been implemented, had gained more weight. Overall lamb mortality was 6.8% with most deaths occurring before 1 month of age. This study highlights that health interventions in ewes improve lamb survival and weight gain and that the care of lambs during the first month of life is crucial for overall herd productivity

Seroepidemiology of selected transboundary animal diseases in goats in Zambia

Transboundary pathogens of goats present significant constraints to the livelihoods of millions of farmers in countries such as Zambia. Consequently, this study aimed to investigate the seroprevalence of Mycoplasma capricolum subsp. capripneumoniae (Mccp), foot and mouth disease virus (FMDV), Brucella spp., Crimean Congo haemorrhagic fever virus (CCHFV), and Rift Valley fever virus (RVFV) in Zambian goats. Another aim was to identify associations between seroprevalence and different predictor variables, such as trade and border proximity. From September to October 2019, 962 serum samples were collected from goats in seven Zambian districts, four of which have an international border while the remaining three do not. A questionnaire survey was conducted with each household, focusing on trade routines, management strategies and herd disease history. Animal-level seroprevalence adjusted for herd-level clustering was 8.2 % (95 % confidence interval [CI] 7.5-9.0) for Mccp, 12.9% (95% CI 12.0-13.7) for FMDV, 13.0 % (95% CI 12.1-13.9) for Brucella spp., 3.3 % (95% CI 2.8-3.7) for CCHFV, and 0.4 % (95 % CI 0.3-0.7) for RVFV. The association between herd-level seroprevalence and border proximity and trade appeared negligible, with the exception of selling goats at least twice a year which was identified as a potential risk factor for Brucella spp. (OR 4.1, 95 % CI 1.1-16.0, p = 0.040). In addition, a positive association between herd-level seroprevalence of FMDV and a herd size of 21 goats or more (OR 3.3, 95 % CI 1.0-11.1, p = 0.049) was detected. Also, positive associations between animal-level seroprevalence of Brucella spp. and increasing age (OR 7.7, 95 % CI 1.5-40.7, p = 0.016), and CCHFV and keeping pigs in the household (OR 2.7, 95 % CI 1.0-7.1, p = 0.044), were found. For FMDV (OR 3.8, 95 % CI 1.4-10.9, p = 0.011) and Brucella spp. (OR 4.5, 95 % CI 1.2-17.3, p = 0.031) on the other hand, animal-level seroprevalence was significantly higher in households without pigs. To the best of the authors' knowledge, this is the first study to describe the presence of antibodies for CCPP and CCHF in the Zambian goat population. While the association between seroprevalence and trade and border proximity generally appeared negligible, it is recommended that their influence is further evaluated in future studies, preferably through in-depth longitudinal studies incorporating impacts of different biosecurity measures and trade variations, linked to for example seasonality and trade peaks

Zambiska får- och djurhandlares resonemang och ageranden gällande hälsa och sjukdom hos små idisslare

The data is collected at the two largest small livestock markets in Zambia, i.e. Lusaka and Kasumbalesa small livestock markets, in April, May, September 2018, and November 2019. The main method of data collection is semistructured interviews but observations were also conducted. Data collection was focused on traders but market customers, slaughterhouse workers, transporters, veterinary shop workers and employees at the small livestock trade organisation SALZ, were also interviewed. The main purpose was to investigate the perceptions and practices of Zambian traders of small ruminants concerning sheep and goat health and disease. The ethical review was conducted by ILRI Institutional Research Ethics Committee (ILRI IREC).Datamaterialet är insamlat på de två största får- och getmarknaderna i Zambia, nämligen Lusaka och Kasumbalesa, i april, maj, september 2018 och november 2019. Materialet har huvudsakligen samlats in genom semi-strukturerade intervjuer men även med hjälp av observationer. Datainsamlingen var fokuserad på djurhandlare men även marknadskunder, slaktare, transportörer, veterinärbutiks-arbetare samt anställda på marknadsorganisationen SLAZ, intervjuades. Det huvudsakliga syftet med datainsamlingen var att undersöka hur zambiska djurhandlare resonerar och agerar kring hälsa och sjukdomar hos får och getter. Studien är etikprövad av International Livestock Research Institutes (ILRI) nämnd ILRI Institutional Research Ethics Committee (ILRI IREC)

Crossing the line – Tracking transboundary diseases in trade and across international borders in Zambia and Tanzania

Transboundary diseases in small ruminants constitute a threat to health, livelihoods and society in Zambia and Tanzania. Animal trade and movement, both of which tend to increase close to international borders, are known drivers of disease spread. This thesis was guided by three overarching aims. The first aim was to investigate the impact of trade and border proximity on the seroprevalence of peste des petits ruminants (PPR), contagious caprine pleuropneumonia (CCPP), foot and mouth disease (FMD), sheeppox and goatpox (SGP), Rift Valley fever (RVF), Crimean-Congo haemorrhagic fever (CCHF) and brucellosis in sheep and goats in Zambia and in the Tanzania-Zambia border region. The second aim was to investigate how the perceptions and practices of Zambian small ruminant traders and slaughterhouse workers influence the risk of disease spread. The third aim was to investigate the seropositivity rate of brucellosis, Q-fever and RVF in sheep and goats in Zambia’s two largest small ruminant markets, and risks for exposure to these and other zoonotic diseases at a market slaughterhouse. To meet these aims, seroepidemiology was combined with semi-structured interviews, focus group discussions and observations. The results indicated that most of the surveyed pathogens are circulating in parts of Zambia and Tanzania, and proximity to international borders was generally associated with reduced seroprevalence. While the impact of trade on seroprevalence varied, the perceptions and practices of small ruminant traders pose risks of disease dissemination through trade. The presence of zoonotic pathogens at small ruminant markets in Zambia coupled with insanitary procedures at slaughter represent potential threats to public health. In conclusion, small ruminant transboundary diseases pose serious risks. Informed control strategies adapted to the local context could mitigate these risks, improving the health and welfare of animals and humans alike

Perceptions and practices among Zambian sheep and goat traders concerning small ruminant health and disease

Trade in animals and animal products is a key factor in the transmission of infectious diseases. Livestock traders play an important role in this process, yet there is little knowledge of traders' perceptions of animal disease or their associated actions. The aim of this study was to investigate perceptions and practices of Zambian small ruminant traders with regard to sheep and goat health and disease. It also analysed how existing perceptions and practices might affect risks of disease transmission through trade. A case study was performed at the two largest small livestock markets in Zambia: the Lusaka market in the capital and the Kasumbalesa market near the border with the Democratic Republic of Congo. Semi-structured interviews with 47 traders performed in April-May and September 2018 represent the core material. Zambian small ruminant traders frequently trade animals that have clinical signs of disease, either because they appear unaware or indifferent to the associated risks, experience financial constraints or assign responsibility for disease prevention to other value chain actors. In their decision about whether or not to sell a visibly sick small ruminant, traders appear to consider whether the clinical sign is perceived as 'natural' or the result of an illness, whether the buyer is aware of the animal's health condition, and whether the animal is sold for consumption or breeding purposes. Traders appear to regard the veterinary certificate required to transport small ruminants in Zambia as proof of health, placing the responsibility for potential disease in traded animals on the veterinary authorities. In their description of a model trader, taking good care of and being sensitive to customer needs was emphasized, indicating that an efficient way to encourage traders to change their behaviour is to influence customer demands. In contrast to the focus in previous studies on identifying and filling knowledge gaps, the present study show that lack of knowledge is not central to why traders engage in disease-transmitting behaviour. Greater awareness of other reasons for certain perceptions and practices could lead to the formulation of risk communication strategies and mitigation measures that are relevant for the local context, as well as alternative strategies for changing trader behaviour

Seropositivity rates of zoonotic pathogens in small ruminants and associated public health risks at informal urban markets in Zambia

Informal livestock markets are an important source of animal-derived proteins for growing urban populations in countries such as Zambia. In parallel, they can also constitute pathways of zoonotic pathogen transmission to humans. This risk is aggravated by limited disease monitoring and poor control systems with regards to biosecurity and public health. The aim of this study was to investigate the risks for spread of zoonotic diseases in Zambia's two largest informal small ruminant markets, located in Lusaka and Kasumbalesa, through combining seroepidemiology with interviews and observations. In April, May and September 2018, serum samples (n = 237) were collected and analysed for antibodies for the zoonotic pathogens Brucella spp., Coxiella (C.) burnetii and Rift Valley fever virus (RVFV), using commercially available enzyme linked immunosorbent assays (ELISA). In addition, slaughterhouse activities were observed and semi-structured interviews and focus group discussions held with slaughterhouse workers and small ruminant traders, focusing on the handling of animals and meat, and the perceptions of zoonotic disease risks at slaughter and consumption. The study found seropositivity rates of 10.1% (95% confidence interval [CI] 6.60-14.7) for Brucella spp., 5.9% (95% CI 3.27-9.71) for C. burnetii, and 0.8% (95% CI 0.10-3.01) for RVFV. Interviews with value chain members and observations at the slaughterhouse revealed unsanitary procedures and multiple occupational hazards for slaughterhouse workers. This study showed that the Zambian informal small ruminant trade system poses risks to public health, and that these risks are exacerbated by a lack of information about food-borne diseases and how associated risks can be mitigated amongst value chain actors. The results of this study can be used to formulate preventive measures to improve informal meat markets and reduce the risks to public health

Presence of Anaplasma spp. and Their Associated Antibodies in the Swedish Goat Population

Anaplasmosis is a tick-borne disease that has a severe impact on livestock production and welfare. The aim of this pilot study was to investigate the presence of Anaplasma spp. and associated antibodies in a subset of the Swedish goat population. In 2020, six goat herds located in different parts of Sweden were visited and whole blood and serum samples were collected. The whole blood samples (n = 40) were analysed for the presence of Anaplasma phagocytophilum, A. ovis and A. capra using quantitative and conventional polymerase chain reaction (PCR). The serum samples (n = 59) were analysed for the presence of antibodies to Anaplasma spp. using a commercial competitive enzyme-linked immunosorbent assay, and the same analysis was carried out on additional serum samples previously collected in 2018, 2019 and 2020 (n = 166). One goat (2.5%) tested positive for the presence of A. phagocytophilum genetic material, while the seropositivity rate ranged from 20 to 71%, depending on the surveyed year and area. These results indicate widespread exposure to Anaplasma spp. in the Swedish goat population. To inform future risk assessments and control efforts, further research is warranted to determine the prevalence of anaplasmosis and its impact on goat farming in Sweden