Prevalence and characterization of verotocytoxin producing Escherichia coli O157 from diarrhoea patients in Morogoro, Tanzania

Escherichia coli O157:H7 is an important agent of haemorrhagic colitis and haemolytic uraemic syndrome in children less than five years old and elderly people. The objective of this study was to investigate the prevalence of verotocytoxin producing E. coli 0157 (VTEC O157) among human patients with diarrhoea in Morogoro, Tanzania. Faecal samples originating from 275 human patients with diarrhoea were screened for presence of E. coli O157:H7. A total of 96 E.coli isolate were identified. Of these, 10 isolates were grouped into sorbitol non-fermenting and glucuronide negative and 49 isolates were sorbitol positive and glucuronide positive. The remaining 37 were sorbitol negative and glucuronide positive. Using the polymerase chain reaction techniques, a total of ten verotocytocin producing E. coli isolated in this study were used. The overall two (15%) and one (7%) of the isolated of E. coli possessed both attaching and effacing (eae A) and enterohemolysin (ehly) A genes respectively. Other enterobacterial agents including Pseudomonas spp, Proteus spp and coliforms were also isolated. The VTEC O157 isolates were 100% resistant to oxytetracycline, chloramphenicol, streptomycin, and amoxyclav. In conclusion, the isolation of diarrhoeaogenic E. coli O157:H7 in this region suggests that the pathogen is an important aetiology of acute gastroenteritis in Tanzania. There is therefore, need to improve sewage and refuse disposal system, the provision of safe potable water, sanitation, personal hygiene and health education in order to reduce infection with this and other enteric pathogens

Molecular epidemiology of Salmonella gallinarum in chickens in Tanzania

Avian Pathology, 2000; 29:457– 463A molecular epidemiological investigation of Salmonella gallinarum infection in scavenging local chickens and commercial layers in Tanzania was conducted between August 1997 and April 1998. A total of 1152 chickens were randomly selected from 10 villages and seven commercial farms. For serological and cultural prevalence studies, 1152 blood samples and 912 cloacal swabs were collected. In scavenging local chickens, the individual serological and cultural prevalences were 6.3 and 0%, while the prevalences were significantly higher in commercial layers at 18.4 and 2.6% (P < 0.001), respectively. The risk of infection in flocks of scavenging local chickens that had contact with commercial chickens was six times greater than the risk of infection in flocks of scavenging local chickens that had no contact with commercial chickens. Thirty-four S. gallinarum isolated from commercial chickens in this study, together with 29 Tanzanian historical isolates, were characterized using plasmid profiling and ribotyping. Fifty-one isolates contained both 85 and 2.5 kb plasmids, five isolates contained only one plasmid of 85 kb, and seven isolates had no plasmids. Ribotyping using HindIII restriction endonuclease demonstrated seven different ribotypes. Forty-seven isolates had similar results in both typing systems, suggesting they belonged to one clone. It is concluded that S. gallinarum infection in chickens in Tanzania is more prevalent in commercial layers than in scavenging local chickens. One strain of S. gallinarum from chickens first isolated in a Dar es Salaam hatchery was found to be common throughout the country

Productivity and Natural Disease Resistance Potential of Free-ranging Local Chicken Ecotypes in Tanzania

This study was carried out to investigate the productivity and the natural disease resistance potential of free-ranging local chickens in Tanzania. A total of 84 adult free-ranging local chicken ecotypes were studied, namely: Mbeya, Morogoro-medium, Ching’wekwe, Kuchi and Singamagazi. Adult body weight, body length, shank length and egg weight were assessed and compared. Average body weight for hens and cocks was 1441g (800 to 2,300g) and 2261g (1000 to 3500g), respectively. Egg weight averaged 41.6g (27 to 72g). Mean body length for hens and cocks was 21.6cm (17 to 26cm) and 24.6cm (21 to 29cm), respectively, and mean shank length 9.7cm (7 to 12cm) and 12.7cm (8.5 to 15cm), respectively. Between ecotypes significant differences were seen in the above parameters. The disease resistance potential was tested on 10 offspring of each ecotype, excluding the Mbeya. Twenty chickens (five from each of the four ecotypes) aged 12 weeks were inoculated with Newcastle disease virus while another 20 aged 20 weeks were inoculated with Salmonella gallinarum. Five chickens per group that were not challenged were used as controls. Following oral, ocular and nasal drop inoculation with Newcastle disease virus, the chickens developed clinical signs of Newcastle disease as from day three after infection. Mortality started on day five after infection, and all but one chicken were dead by day seven after infection. The 20 chickens, infected orally with S. gallinarum, showed clinical signs of fowl typhoid on day three after infection. Mortalities started on day seven after infection and by day 12 after infection 13 chickens had died. Seven birds survived without visible signs of the disease, including all five from the Kuchi ecotype and one each of the Morogoro-medium and Ching’wekwe ecotypes. At necropsy enlarged and congested liver and spleen, and catarrhal enteritis of the small intestines were seen. The surviving birds were sacrificed on day 14 after infection. Neither the sacrificed surviving birds nor the controls showed the above necropsy picture. It was concluded that free-ranging local chicken ecotypes in Tanzania differ in both productivity and disease resistance potential

A Retrospective Study of Factors associated with Newcastle Disease Outbreaks in Village Indigenous Chickens

Although the epidemiology of Newcastle disease in commercial poultry systems is well documented, its ecology in indigenous birds, especially in tropics, is not adequately reported. The objective of this study, therefore, was to determine the risk factors associated with occurrence of Newcastle disease in village indigenous chickens. The study was carried out in five agro –ecological zones and seventy five households keeping indigenous chickens. Farmers were randomly selected and assessed on whether they understood Newcastle disease including knowing its local name and clinical signs manifested by the affected birds. Those who did not fit into the above category were excluded from further interviews. Data on management practices, incidence of diseases and risk factors associated with Newcastle disease outbreaks were collected using a questionnaire and analysed using statistical package. The prevalence rate of Newcastle disease was highest (93.8%) in the dry zone (Low midland 5) and lowest (50%) in cool wet zone (Lower Highland 1). Newcastle disease outbreaks were significantly associated with the following factors namely: confinement of birds in all ecological zones except in lower midland 5 where most cases were reported without confinement; mode of disposal of infected birds, carcasses and poultry faecal matter; dry seasons in the dry zones just before the rains; wind conditions; short intermittent temperature changes and the restocking of farms with chickens from the markets (P0.05) associated with Newcastle disease outbreaks. The responses varied across the seasons and between the agro – ecological zones. In conclusion, the study has shown that several factors namely: confinement; cold or very hot temperatures; winds; introduction of market birds and disposal of manure and sick birds are major risk factors to occurrence of Newcastle disease in indigenous chickens. It is recommended that flock owners be educated on Newcastle disease transmission and prevention.Key – words: risk factors, agro–ecological zones, confinement, hot and cold season

Phenotypes including immunocompetence in scavenging local chicken ecotypes in Tanzania

A study was conducted to determine the variations in physical characters and immunocompetence among scavenging local chicken ecotypes in Tanzania. Eighty-four adult scavenging local chickens from four eco-climatic regions of Tanzania were studied. Measurements of adult body weight, body length, shank length and egg weight and observations of plumage colour and pattern, earlobe colour, skin colour and the shape of the comb were conducted. The antibody response to sheep red blood cells, serum haemolytic complement and the cutaneous response to phytohaemagglutinin-P were assessed. Five ecotypes were identified nd named Mbeya, Morogoro-medium, Ching'wekwe, Kuchi and Singamagazi. Singamagazi and Kuchi were significantly heavier, with longer shanks and heavier eggs than the other ecotypes. The average adult body weight for males ranged from 1621 g (Mbeya) to 2915 g (Singamagazi). Average female weights ranged from 1108 g (Morogoro-medium) to 2020 g (Singamagazi). Mean egg weights ranged from 37.65 g (Ching'wekwe) to 45.61 (Singamagazi). The Kuchi had mostly rose and walnut combs, while the other ecotypes were mostly single combed. In each ecotype there were chickens with a high or low antibody response to red blood cells, but there was a significant difference between the ecotypes