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Kabeta T, Tolosa T, Duchateau L, Immerseel FV, Antonissen G. Prevalence and Serotype of Poultry Salmonellosis in Africa: a Systemic Review and Meta-Analysis. Avian Pathol 2024:1-61. [PMID: 38639048 DOI: 10.1080/03079457.2024.2344549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
Salmonellosis represents a significant economic and public health concern for the poultry industry in Africa, leading to substantial economic losses due to mortality, reduced productivity, and food safety problems. However, comprehensive information on the burden of poultry salmonellosis at the continental level are scarce. To address this gap, a systemic review and meta-analysis were conducted to consolidate information on the prevalence and circulating serotypes of poultry salmonellosis in African countries. This involved the selection and review of 130 articles published between 1984 and 2021. A detailed systematic review protocol was structured according to Cochrane STROBE and PRISMA statement guidelines. From the 130 selected articles from 23 different African countries, the overall pooled prevalence estimate (PPE) of poultry salmonellosis in Africa was found to be 14.4% (95% CI= 0.145-0.151). Cameroon reported the highest PPE at 71.9%, with the country also noting the highest specific prevalence of 93.3%. The PPE was notably high in meat and meat products at 23%, indicating significant contamination of Salmonella in African poultry meat and meat products. The number of research papers reporting poultry salmonellosis in Africa has been a threefold increase from 1984 to 2021. Salmonella Enteritidis and Typhimurium were the two most prevalent serotypes reported in 18 African countries. Besides, Salmonella Kentucky, Virchow, Gallinarum, and Pullorum were also widely reported. Western Africa had the highest diversity of reported Salmonella serotypes (141), in contrast to southern Africa, which reported only 27 different serotypes. In conclusion, poultry salmonellosis is highly prevalent across Africa, with a variety of known serotypes circulating throughout the continent. Consequently, it is crucial to implement strategic plans for the prevention and control of Salmonella in Africa.
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Affiliation(s)
- Tadele Kabeta
- Jimma University, College of Agriculture and Veterinary Medicine, School of Veterinary Medicine, P.O. Box 307, Jimma, Ethiopia
- Ghent University, Faculty of Veterinary Medicine, Department of Pathobiology, Pharmacology, and Zoological Medicine, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Tadele Tolosa
- Jimma University, College of Agriculture and Veterinary Medicine, School of Veterinary Medicine, P.O. Box 307, Jimma, Ethiopia
| | - Luc Duchateau
- Ghent University, Faculty of Veterinary Medicine, Biometrics Research Group, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Filip Van Immerseel
- Ghent University, Faculty of Veterinary Medicine, Department of Pathobiology, Pharmacology, and Zoological Medicine, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Gunther Antonissen
- Ghent University, Faculty of Veterinary Medicine, Department of Pathobiology, Pharmacology, and Zoological Medicine, Salisburylaan 133, 9820 Merelbeke, Belgium
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Salmonella Gallinarum in Small-Scale Commercial Layer Flocks: Occurrence, Molecular Diversity and Antibiogram. Vet Sci 2021; 8:vetsci8050071. [PMID: 33922826 PMCID: PMC8145292 DOI: 10.3390/vetsci8050071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 04/19/2021] [Accepted: 04/21/2021] [Indexed: 11/22/2022] Open
Abstract
Salmonella Gallinarum is one of the most important bacterial pathogens associated with diminished egg production in poultry. The aim of this study was to understand the occurrence, molecular traits and antimicrobial resistance patterns of Salmonella Gallinarum strains isolated from small-scale commercial layer flocks with low level biosecurity standards in Bangladesh. A total of 765 samples, including cloacal swabs (535), visceral organs (50), and droppings (180), were collected from chickens of 12 layer flocks in 11 districts. Salmonella Gallinarum was isolated and characterized through culture-based method, followed by biochemical tests, sero-grouping, PCR assays, sequencing, and antibiogram. The identity of biochemically detected isolates of Salmonella Gallinarum was confirmed via genus-specific 16S rRNA gene based PCR, followed by invA and spvC genes based PCR assays. Occurrence of Salmonella Gallinarum was detected in overall 25.75% (197/765) samples, with a significantly (p < 0.05) higher incidence in visceral organs (42%) in comparison to cloacal swab (24%) and droppings (26%). Sequencing and subsequent phylogenetic analysis of invA and spvC genes in representative strains of Salmonella Gallinarum revealed a close genetic lineage, with a sequence similarity of 98.05–99.21% and 97.51–99.45%, respectively, to previously published sequences of the corresponding genes from the same serogroup strains. Remarkably, 66.5% (131/197) of the isolated strains of Salmonella Gallinarum were found to be resistant to 3 to 6 antimicrobial agents, and interpreted as multidrug resistant (MDR). The findings of this study underscore an inherent need of appropriate control measures to curb the widespread incidence of MDR Salmonella Gallinarum in small-scale commercial layer flocks, thereby, facilitating enhanced egg production and further support to the food security and safety in low resource settings.
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Thomas KM, de Glanville WA, Barker GC, Benschop J, Buza JJ, Cleaveland S, Davis MA, French NP, Mmbaga BT, Prinsen G, Swai ES, Zadoks RN, Crump JA. Prevalence of Campylobacter and Salmonella in African food animals and meat: A systematic review and meta-analysis. Int J Food Microbiol 2020; 315:108382. [PMID: 31710971 PMCID: PMC6985902 DOI: 10.1016/j.ijfoodmicro.2019.108382] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 08/20/2019] [Accepted: 10/02/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND Campylobacter and Salmonella, particularly non-typhoidal Salmonella, are important bacterial enteric pathogens of humans which are often carried asymptomatically in animal reservoirs. Bacterial foodborne infections, including those derived from meat, are associated with illness and death globally but the burden is disproportionately high in Africa. Commercial meat production is increasing and intensifying in many African countries, creating opportunities and threats for food safety. METHODS Following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, we searched six databases for English language studies published through June 2016, that reported Campylobacter or Salmonella carriage or infection prevalence in food animals and contamination prevalence in food animal products from African countries. A random effects meta-analysis and multivariable logistic regression were used to estimate the species-specific prevalence of Salmonella and Campylobacter and assess relationships between sample type and region and the detection or isolation of either pathogen. RESULTS Seventy-three studies reporting Campylobacter and 187 studies reporting Salmonella across 27 African countries were represented. Adjusted prevalence calculations estimate Campylobacter detection in 37.7% (95% CI 31.6-44.3) of 11,828 poultry samples; 24.6% (95% CI 18.0-32.7) of 1975 pig samples; 17.8% (95% CI 12.6-24.5) of 2907 goat samples; 12.6% (95% CI 8.4-18.5) of 2382 sheep samples; and 12.3% (95% CI 9.5-15.8) of 6545 cattle samples. Salmonella were detected in 13.9% (95% CI 11.7-16.4) of 25,430 poultry samples; 13.1% (95% CI 9.3-18.3) of 5467 pig samples; 9.3% (95% CI 7.2-12.1) of 2988 camel samples; 5.3% (95% CI 4.0-6.8) of 72,292 cattle samples; 4.8% (95% CI 3.6-6.3) of 11,335 sheep samples; and 3.4% (95% CI 2.2-5.2) of 4904 goat samples. 'External' samples (e.g. hide, feathers) were significantly more likely to be contaminated by both pathogens than 'gut' (e.g. faeces, cloaca) while meat and organs were significantly less likely to be contaminated than gut samples. CONCLUSIONS This study demonstrated widespread prevalence of Campylobacter species and Salmonella serovars in African food animals and meat, particularly in samples of poultry and pig origin. Source attribution studies could help ascertain which food animals are contributing to human campylobacteriosis and salmonellosis and direct potential food safety interventions.
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Affiliation(s)
- Kate M Thomas
- Centre for International Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand; Kilimanjaro Clinical Research Institute, Good Samaritan Foundation, Moshi, United Republic of Tanzania.
| | - William A de Glanville
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical Veterinary & Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | | | | | - Joram J Buza
- School of Life Sciences and Bio-Engineering, Nelson Mandela African Institution of Science and Technology, Arusha, United Republic of Tanzania
| | - Sarah Cleaveland
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical Veterinary & Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Margaret A Davis
- Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, United States of America
| | - Nigel P French
- mEpiLab, Massey University, Palmerston North, New Zealand; New Zealand Food Safety Science and Research Centre, New Zealand
| | - Blandina T Mmbaga
- Kilimanjaro Clinical Research Institute, Good Samaritan Foundation, Moshi, United Republic of Tanzania
| | - Gerard Prinsen
- School of People, Environment and Planning, Massey University, Palmerston North, New Zealand
| | - Emmanuel S Swai
- State Department of Veterinary Services, Ministry of Livestock and Fisheries, Dodoma, United Republic of Tanzania
| | - Ruth N Zadoks
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical Veterinary & Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - John A Crump
- Centre for International Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
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Sindiyo E, Maganga R, Thomas KM, Benschop J, Swai E, Shirima G, Zadoks RN. Food Safety, Health Management, and Biosecurity Characteristics of Poultry Farms in Arusha City, Northern Tanzania, Along a Gradient of Intensification. East Afr Health Res J 2018; 2:168-180. [PMID: 34308188 PMCID: PMC8279270 DOI: 10.24248/eahrj-d-18-00034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 09/27/2018] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND With the growth, urbanisation, and changing consumption patterns of Tanzania's human population, new livestock production systems are emerging. Intensification of poultry production may result in opportunities and threats for food safety, such as improved awareness of biosecurity or increasing prevalence of foodborne pathogens including nontyphoidal Salmonella or Campylobacter spp. We conducted a semiquantitative analysis of poultry production systems in northern Tanzania, with emphasis on biosecurity, health management practices, and prevalence of foodborne pathogens, to gain insight into potential associations between intensification and food safety. METHODS Interviews were conducted with managers of 40 poultry farms, with equal representation of 4 production systems (extensive, semi-intensive, or intensive production with indigenous chickens, and broiler farming). Per farm, up to 10 birds (total, 386) were tested for cloacal shedding of nontyphoidal Salmonella, with a subset of farms tested for Campylobacter. Data were analysed using univariate statistics, and results were discussed during feedback workshops with participating farmers and extension officers. RESULTS Clear differences existed between farm types with regard to implementation of biosecurity and health management practices and use of extension services. By contrast, prevalence of foodborne pathogens (6 of 40 farms or 15% for nontyphoidal Salmonella and 13 of 26 farms or 50% for Campylobacter spp.) was not farm-type specific, indicating that it is driven by other factors. Across farming systems, knowledge and awareness of the presence of antimicrobials in poultry feed and the need to abide by post-treatment withdrawal times were limited, as was access to impartial professional advice regarding treatment. CONCLUSION Different control measures may be needed to protect poultry health compared to public health, and improvements in information provision may be needed for both.
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Affiliation(s)
- Emmanuel Sindiyo
- School of Life Sciences and Bio-Engineering, Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
| | - Ruth Maganga
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Kate M Thomas
- Department of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Jackie Benschop
- EpiLab, School of Veterinary Science, Massey University, Palmerston North, New Zealand
| | - Emmanuel Swai
- Ministry of Livestock and Fisheries Development, Dar es Salaam, Tanzania
| | - Gabriel Shirima
- School of Life Sciences and Bio-Engineering, Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
| | - Ruth N Zadoks
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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Nyabundi D, Onkoba N, Kimathi R, Nyachieo A, Juma G, Kinyanjui P, Kamau J. Molecular characterization and antibiotic resistance profiles of Salmonella isolated from fecal matter of domestic animals and animal products in Nairobi. TROPICAL DISEASES TRAVEL MEDICINE AND VACCINES 2017; 3:2. [PMID: 28883972 PMCID: PMC5530968 DOI: 10.1186/s40794-016-0045-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Accepted: 12/18/2016] [Indexed: 11/26/2022]
Abstract
Background Salmonella has significant public health implications causing food borne and zoonotic diseases in humans. Treatment of infections due to Salmonella is becoming difficult due to emergence of drug resistant strains. There is therefore need to characterize the circulating non-typhoidal Salmonella (NTS) serovars in domestic animals and animal products in Kenya as well as determine their antibiotic resistance profiles. Methods A total of 740 fecal samples were collected from cows (n = 150), pigs (n = 182), chicken (n = 191) and chicken eggs (n = 217) from various markets and abattoirs in Nairobi. The prevalence of NTS serovars using culture techniques and biochemical tests, antimicrobial sensitivity testing using disc diffusion method of the commonly prescribed antibiotics and phylogenetic relationships using 16S rRNA were determined. Results The results showed that the overall prevalence of Salmonella was 3.8, 3.6, 5.9 and 2.6% for pigs, chicken, eggs and cows respectively. Two serovars were isolated S. Typhimurium (85%) and S. Enteritidis (15%) and these two serovars formed distinct clades on the phylogenetic tree. Forty percent of the isolates were resistant to one or more antibiotics. Conclusion The isolation of Salmonella Typhimurium and Salmonella Enteritidis that are resistant to commonly used antibiotics from seemingly healthy animals and animal products poses a significant public health threat. This points to the need for regular surveillance to be carried out and the chain of transmission should be viewed to ascertain sources of contamination.
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Affiliation(s)
- Diana Nyabundi
- Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
| | - Nyamongo Onkoba
- Institute of Primate Research, P.O. Box 24481-00502, Karen, Nairobi, Kenya
| | - Rinter Kimathi
- Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
| | - Atunga Nyachieo
- Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya.,Institute of Primate Research, P.O. Box 24481-00502, Karen, Nairobi, Kenya
| | - Gerald Juma
- Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
| | - Peter Kinyanjui
- Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
| | - Joseph Kamau
- Department of Biochemistry, School of Medicine, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya.,Institute of Primate Research, P.O. Box 24481-00502, Karen, Nairobi, Kenya
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Samanta I, Joardar S, Das P, Sar T, Bandyopadhyay S, Dutta T, Sarkar U. Prevalence and antibiotic resistance profiles ofSalmonella serotypes isolated from backyard poultry flocks in West Bengal, India. J APPL POULTRY RES 2014. [DOI: 10.3382/japr.2013-00929] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Mitra A, Loh A, Gonzales A, Laniewski P, Willingham C, Curtiss Iii R, Roland KL. Safety and protective efficacy of live attenuated Salmonella Gallinarum mutants in Rhode Island Red chickens. Vaccine 2012; 31:1094-9. [PMID: 23261043 DOI: 10.1016/j.vaccine.2012.12.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 11/01/2012] [Accepted: 12/10/2012] [Indexed: 01/17/2023]
Abstract
Salmonella enterica serovar Gallinarum is the causative agent of fowl typhoid, an important systemic disease of poultry with economic consequences in developing nations. A live attenuated orally applied S. Gallinarum vaccine could provide a low cost method for controlling this disease. We constructed S. Gallinarum strains in which the expression of the crp, rfc and rfaH genes, important for virulence of Salmonella Typhimurium in mice, were under the control of an arabinose-regulated promoter. We evaluated the virulence of these strains compared to wild-type S. Gallinarum and to mutants carrying deletions in these genes. We found that rfc mutants were fully virulent, indicating that, unlike the S. Typhimurium mouse model, the rfc gene is dispensable in S. Gallinarum for virulence in birds. In the case of rfaH, the deletion mutant was attenuated and protective, while the strain with arabinose-regulated rfaH expression retained full virulence. The strain exhibiting arabinose-regulated crp expression was attenuated. Its virulence was not affected by the inclusion of 0.2% arabinose in the drinking water. Birds immunized with this strain were protected against a lethal S. Gallinarum challenge and against colonization with the human pathogen Salmonella Enteritidis. This work shows that an arabinose-regulated crp strain provides a basis for further development of a fowl typhoid vaccine.
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Affiliation(s)
- Arindam Mitra
- The Biodesign Institute, School of Life Sciences, Arizona State University, Tempe, AZ 85287, United States
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Kwon YK, Kim A, Kang MS, Her M, Jung BY, Lee KM, Jeong W, An BK, Kwon JH. Prevalence and characterization ofSalmonella Gallinarum in the chicken in Korea during 2000 to 2008. Poult Sci 2010; 89:236-42. [DOI: 10.3382/ps.2009-00420] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Msoffe PLM, Minga UM, Mtambo MMA, Gwakisa PS, Olsen JE. Differences in resistance toSalmonella entericaserovar Gallinarum infection among indigenous local chicken ecotypes in Tanzania. Avian Pathol 2007; 35:270-6. [PMID: 16854638 DOI: 10.1080/03079450600817024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
A study was conducted to evaluate the disease resistance potential in 105 chickens of six indigenous local chicken ecotypes in Tanzania by orally challenging 1-week-old chicks with 2.5 x 10(8) colony-forming units of virulent S. Gallinarum. For 14 days post infection, clinical signs, necropsy findings, antibody titres, packed cell volume, leukocyte population count, and viable bacterial cell counts in the liver and spleen were recorded. Clinical signs were recorded daily but other parameters were recorded on the day of infection, then on days 3, 6, 10 and 14 after infection. Clinical signs of fowl typhoid were evident in chickens from day 3 post infection and disappeared by day 9 post infection. Pathological lesions on sacrificed birds included enlargement of the liver and spleen with foci of necrosis on the liver, spleen and myocardium. The mean viable bacterial cell counts in the liver and spleen varied between ecotypes, although the differences were not statistically significant. There were significant differences in the leukocyte population in the peripheral blood, with one ecotype (Morogoro-medium) showing a consistent and significantly higher heterophil count compared with other ecotypes. It was concluded that there is a selectable resistance potential to S. Gallinarum among the local chicken ecotypes in Tanzania that may be attributable to non-specific host immune responses. Further studies are suggested.
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Affiliation(s)
- P L M Msoffe
- Department of Veterinary Medicine and Public Health, P.O. Box 3021, Morogoro, Tanzania.
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Liebana E. Molecular tools for epidemiological investigations of S. enterica subspecies enterica infections. Res Vet Sci 2002; 72:169-75. [PMID: 12076110 DOI: 10.1053/rvsc.2001.0550] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Salmonella infection is one of the most prevalent reported food-borne diseases in industrialised countries, most often associated with eating contaminated eggs, poultry and pork. Traditionally, epidemiological investigations for Salmonella enterica have been based on phenotypic characteristics. However, the predominance of certain phenotypes within hosts or locations makes further epidemiological subgrouping necessary. The combination of conventional and molecular epidemiology data is yielding important insights into the understanding of the epidemiology of many infectious diseases, although at present there is no consensus on which molecular method is best suited for intraserotype differentiation within S. enterica. This paper reviews the current methodology for some of the most prevalent animal and human-associated serotypes.
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Affiliation(s)
- E Liebana
- Department of Bacterial Diseases, Veterinary Laboratories Agency-Weybridge, Addlestone, Surrey, KT15 3NB, UK.
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Mdegela RH, Msoffe PLM, Waihenya RW, Kasanga JC, Mtambo MMA, Minga UM, Olsen JE. Comparative pathogenesis of experimental infections with Salmonella gallinarum in local and commercial chickens. Trop Anim Health Prod 2002; 34:195-204. [PMID: 12094675 DOI: 10.1023/a:1015226507721] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The pathogenicity of a virulent strain of Salmonella gallinarum was studied in local chickens and commercial layers. Sixty 4-month-old chickens were used. Of these, 50 chickens were orally infected with S. gallinarum, comprising 25 commercial layers and 25 local chickens. Five chickens in each group were used as uninfected negative controls. The clinical signs and pathological features of acute, subacute and chronic fowl typhoid were observed in both groups. Chickens in both groups seroconverted, but the antibody titre was significantly higher (p < 0.001) in the commercial layers. The antibody titre remained high to the end of the experiment in all the surviving chickens. Only one commercial layer chicken died during the course of the experiment. The PCV decreased significantly (p < 0.001) in the infected chickens of both groups as compared to the controls. The viable cell count of S. gallinarum in the liver and spleen reached a maximum on day 9 after infection in both groups. However, there was a significantly higher cell count (p < 0.05) in the commercial layers. The severity of the disease appeared to be slightly greater in the commercial layers, although the susceptibility was similar in both groups. It was concluded that, under experimental conditions, local chickens are just as susceptible to S. gallinarum infection as are commercial layers.
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Affiliation(s)
- R H Mdegela
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, PO Box 3021, Morogoro, Tanzania
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