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Biomedical subjects

S M Arimi

Publications and source records attributed to S M Arimi.

At least 19 recordsLinked to original sources
PubMed2005

Risk of infection with Brucella abortus and Escherichia coli O157:H7 associated with marketing of unpasteurized milk in Kenya.

As part of a study to assess zoonotic milk-borne health risks, seasonal survey data and unpasteurized milk samples were collected between January 1999 and February 2000 from randomly selected informal milk market agents (220 and 236 samples in the dry and wet seasons, respectively) and from households purchasing raw milk (213 and 219 samples in the dry and wet seasons, respectively) in rural and urban locations in central Kenya and screened for antibodies to Brucella abortus (B. abortus) and presence of Escherichia coli (E. coli) O157:H7. The latter was assessed based on samples from consumer households only. Antibodies to B. abortus were screened using the indirect antibody Enzyme Linked Immunosorbent Assay (ELISA) and the Milk Ring Test (MRT). The presence of E. coli O157:H7 was assessed by culture, biochemical characterisation, serological testing for production of verocytotoxin one (VT1) and two (VT2) and polymerase chain reaction (PCR) analysis for the presence of genes encoding for the toxins. The prevalence of antibodies to B. abortus varied considerably ranging from none in milk sold in small units and originating from intensive production systems to over 10% in samples that were bulked or originating from extensive production systems. E. coli O157:H7 was isolated from two samples (0.8%), one of which produced VT1. All urban consumers (100%) and nearly all rural consumers (96%) of marketed milk boiled the milk before consumption, mainly in tea, thus greatly reducing chances of exposure to live pathogens and potential health risks.

Animals↗
PubMed2002

Brucellosis in sub-Saharan Africa: epidemiology, control and impact.

Brucellosis is an important disease among livestock and people in sub-Saharan Africa. In general, the incidence is the highest in pastoral production systems and decreases as herd size and size of landholding decreases. The prevalence of risk factors for infections are best understood for bovine brucellosis and to a lesser extent for ovine and caprine brucellosis. The occurrence and epidemiology of brucellosis in pigs is poorly understood. This species bias is also reflected in control activities. As with other public-sector animal health services, the surveillance and control of brucellosis in sub-Saharan Africa is rarely implemented outside southern Africa. Brucellosis is even more ignored in humans and most cases go undiagnosed and untreated, leading to considerable suffering for those affected. Decision-making to determine the importance of brucellosis control relative to other public concerns and what brucellosis control strategies should be applied is urgently required. A strategy for how brucellosis decision-making might be considered and applied in future is outlined.

Africa South of the Sahara↗
PubMed2001

Foodborne diseases in Kenya.

OBJECTIVES: To determine the occurrence of foodborne disease outbreaks in Kenya and the efforts employed to combat them. DESIGN: Cross-sectional survey. SETTING: Forty two districts in Kenya between 1970 and 1993. STUDY SUBJECTS: Foodborne disease outbreak episodes due to Staphylococcus aureus, Clostridium perfringens, Clostridium botulinum, Bacillus cereus, Escherichia coli, Campylobacter jejuni, Yersinia enterocolitica, Listera monocytogenes, chemicals, aflatoxin, plant and animal poisons. OUTCOME MEASURES: Number and aetiological causes of foodborne disease outbreaks reported in the study period. RESULTS: Thirty seven food poisoning outbreaks were reported to the Ministry of Health from various parts of the country in the study period 1970 to 1993, and only 13 of these involving a total of 926 people were confirmed to be due to particular aetiological agents. Foods that were involved included milk and milk products, meat and meat products, maize flour, bread, scones and other wheat products, vegetables and lemon pie pudding. A high number of food poisoning cases were treated as outpatients in various health facilities. CONCLUSION: Under-reporting, inadequate investigation of outbreaks and inadequate diagnostic facilities suggest that foodborne disease outbreaks are more than is recorded by the Ministry of Health.

Animals↗
PubMed2001

Molecular epidemiology of Bacillus cereus food poisoning.

OBJECTIVES: To investigate the potential use of DNA techniques in epidemiological diagnosis of Bacillus cereus food poisoning. SUBJECTS: Fifty six B. cereus isolates from milk were studied. DESIGN: The 56 B. cereus isolates were characterised into enterotoxin positive (27 isolates) and enterotoxin negative (29 isolates) using reverse passive latex agglutination technique. SETTING: Plasmid and genomic DNA were isolated from all the B. cereus isolates. The plasmid DNA was analysed by gel electrophoresis, while genomic DNA was used for restriction endonuclease and toxin gene analyses. MAIN OUTCOME MEASURES: Plasmid profile analysis, restriction endonuclease analysis of genomic DNA, and test for bceT and hblA genes by polymerase chain reaction and gene probing. RESULTS: Seventy two per cent of the isolates contained one to five plasmids of molecular sizes between 0.1 to 60 mDa. Restriction analysis of genomic DNA gave different restriction patterns among enterotoxin positive and enterotoxin negative isolates. A polymerase chain reaction assay detected bceT gene in 41.1% of the isolates, 16% of which tested positive for enterotoxin with B. cereus enterotoxin reverse passive latex agglutination (BCET-RPLA) kit, while hblA gene was detected in all the enterotoxin positive isolates. BceT and hblA gene probes detected the respective genes in all the isolates that also tested positive for toxin genes by polymerase chain reaction. CONCLUSION: DNA techniques provide an alternative approach to the diagnosis of enterotoxigenic B. cereus.

Animals↗
PubMed1999

Impact of mastitis control measures on milk production and mastitis indicators in smallholder dairy farms in Kiambu district, Kenya.

Bovine mastitis and mastitis control were investigated on smallholder farms in central Kenya. After an initial observational study, a clinical trial to assess the impact of three different mastitis control strategies--(1) improved udder hygiene, (2) treatment of subclinical cases, and (3) a combination of these--was conducted on 100 randomly selected farms with 332 lactating cows. Before the implementation of control measures, the milk yield was low (mean 6.5 kg/day; median 6 kg/day) and somatic cell counts (SCC) were high, with 80% and 43% of cows having milk with SCC greater than 250 x 10(3) cells/ml and 600 x 10(3) cells/ml, respectively. Infectious pathogens were also commonly isolated, with 63% of cows being positive for pathogenic bacteria. Neither intervention strategy alone had any effect on mastitis indicators or milk yield. In combination, the measures had some impact, lowering the prevalence of contagious pathogens by 18%, but this was not reflected in a significantly increased milk yield, lowered SCC or reduced incidence of clinical mastitis.

Animal Husbandry↗
PubMed1999

Retail poultry and beef as sources of Campylobacter jejuni.

OBJECTIVES: To investigate the level of contamination with C. jejuni of raw chicken and beef meats sold in Nairobi and to assess their potential as sources of campylobacter infections to man. DESIGN: Dressed chicken and beef meat samples were randomly sourced from butcheries, markets and supermarkets in various parts of Nairobi over a period of two months. One hundred chicken and 50 beef samples were bacteriologically examined by selective enrichment and culture under microaerophilic environment. Thermophilic campylobacters were identified and characterised using standard physical and biochemical tests. SETTING: Veterinary Public Health Laboratories, Kabete, University of Nairobi. RESULTS: Thermophilic campylobacters were isolated from 77 (77%) poultry samples and one (2%) beef sample. Isolation rate (85.3%) was higher from chickens < 24 hours old since slaughter than those > 24 hours old. The beef isolate was 2% C. jejuni. Poultry samples yielded C. jejuni (59%), C. coli (39% and C. laridis (2%). CONCLUSION: These findings show that poultry meat sold at the counter is a major source of C. jejuni and C. coli, and that it is an important potential source of campylobacter infection. Proper cooking and hygienic handling before consumption is therefore essential.

Animals↗
PubMed1998

Assessment of the Rose-Bengal plate test for the diagnosis of human brucellosis in health facilities in Narok district, Kenya.

The Rose-Bengal plate test (RBPT) was performed on 488 patients with flu-like symptoms from Narok district. There was poor agreement between RBPT results from four health facilities in Narok and from the central veterinary laboratory (CVL). Agreement was poorer for the three rural dispensaries than for the District Hospital. On the other hand, for tests conducted at the CVL, there was good agreement between RBPT, serum agglutination test (SAT) and complement fixation test (CFT) results, indicating that all these tests were probably performing well. Better training and quality control and the use of white rather than a clear background surface for judging agglutination results are recommended to improve the performance of test results in Narok District health facilities.

Adolescent↗
PubMed1997

Bacillus cereus may produce two or more diarrheal enterotoxins.

Bacillus cereus strains were tested for production of diarrheal enterotoxin by the reverse passive latex agglutination test and for presence of B. cereus enterotoxin gene (bceT) by polymerase chain reaction. About 50% of 56 B. cereus strains reacted positive in broth culture in the reverse passive latex agglutination test, while the bceT gene was detected in 41.1%. Sixteen percent of the strains were positive for both diarrheal enterotoxin and bceT gene. A 741 bp probe prepared from the polymerase chain reaction product detected bceT gene in all strains that were positive with the polymerase chain reaction. This study indicates a likelihood of two or more enterotoxins being produced by B. cereus which may be involved in causing diarrheal type food poisoning.

Bacillus cereus↗
PubMed1997

Isolation and characterization of group B streptococci from human and bovine sources within and around Nairobi.

Group B streptococci (GBS) were isolated from bovine milk and from vaginas and throats of antenatal and postnatal women using TKT and rapid GBS media. Sixty-three of 529 (12%) bovine bulk milk samples, 9 of 48 (19%) vaginal and 3 of 48 (6%) throat samples were positive. Both bovine and human beta haemolytic isolates were characterized biochemically and serologically. Pigment production was a characteristic of both human and bovine beta haemolytic isolates. The majority (88%) of human isolates fermented salicin and not lactose and most bovine isolates were either lactose positive/salicin positive (41%) or lactose positive/salicin negative (38%). Human and bovine isolates were 100% and 85% typable respectively. Serotype distribution was similar in the bovine and human populations with serotype la, lc and lll being most common in both. Fermentation of sugars showed major differences between bovine and human isolates but similarity in serotype distribution suggests some genetic relationship.

Animals↗
PubMed1997

Effects of pH on distribution of Listeria ribotypes in corn, hay, and grass silage.

Listeria app, isolated from 13 of 129 (10%) corn silage samples, 21 of 76 (28%) hay silage samples, and 3 of 5 (60%) grass silage samples during a previous Vermont survey were subjected to automated ribotype (RT) analysis. The 13 positive corn silage samples contained 3 Listeria monocytogenes isolated (three RTs, including one known clinical RT) and 10 L. innocua isolates (four RTs). Similarly, 2 L. monocytogenes isolates (two RTs) and 19 L. innocua isolates (three RTs) were identified in the 21 positive hay silage samples. The three positive grass silage samples contained two L. innocua isolates (two RTs) and one isolate of L. welshimeri. One hundred seven of 129 (83%) high-quality (pH < 4.0) corn silage samples accounted for 8 of 13 Listeria isolates from corn silage, including isolates belonging to one L. monocytogenes clinical RT. In contrast, low-quality hay silage (70 of 76 [92%] samples having a pH of > or = 4.0) harbored 20 of 21 isolates, including isolates belonging to two nonclinical L. monocytogenes RTs. Poor-quality silage is readily discernible by appearance; however, these findings raise new concerns regarding the safety of high-quality (pH < 4.0) corn silage, which can contain Listeria spp., including L. monocytogenes strains belonging to RTs of clinical importance in cases of food-borne listeriosis.

Animal Feed↗
PubMed1997

Criteria for better detection of brucellosis in the Narok District of Kenya.

Monthly disease summary sheets from 1986-1992 of 60 dispensaries, clinics and hospitals in Narok district, Kenya were reviewed for the occurrence of brucellosis and other diseases with "flu-like symptoms". Diseases with these symptoms accounted for about 52% of the 1,037,875 cases reported for the time period. These were classified as malaria (79.3%), rheumatism (7.1%), PUO (2.4%), and brucellosis (0.8%). Brucellosis was diagnosed by a positive Rose Bengal (RB) test routinely conducted in seven out of the 60 health units. In these units, 55% of flu-like cases were classified as malaria and 21.2% as brucellosis. Individual case records of patients at four dispensaries using the RB test during 1991-92 were assessed for specific predictor symptoms. For 625 RB tested patients, a positive test result was associated with joint pain, headache, and the combinations of joint pain with headache and lameness with headache. A logistic regression model correctly predicted the RB test result in 62.3% of the time. For the 465 patients examined by the blood smear examination, identification of malaria parasites was associated with, headache, joint pain and combinations of emesis with pale mucous membranes. This regression model correctly predicted positive results 67.2% of the time. Both models indicate that selected clinical predictors represented significantly increased odds of being positive to the respective tests. However, for both diseases, clinical signs alone appear insufficient for reliable diagnosis and differentiation probably due to resemblance in symptomatology between these two and other diseases.

Adolescent↗
PubMed1996

Recovery of different Listeria ribotypes from naturally contaminated, raw refrigerated meat and poultry products with two primary enrichment media.

Isolation rates for Listeria monocytogenes and the other Listeria spp. typically improve when samples are enriched in more than one primary enrichment medium. This study evaluated the abilities of two primary enrichment media, University of Vermont-modified Listeria enrichment broth (UVM) and Listeria repair broth (LRB), to recover different ribotypes of Listeria spp. from raw meat and poultry samples. Forty-five paired 25-g retail samples of ground beef, pork sausage, ground turkey, and chicken (160 samples) underwent primary enrichment in UVM and LRB (30 degrees C for 24 h) followed by secondary enrichment in Fraser broth (35 degrees C for 24 and 40 h) and plating on modified Oxford agar. After 24 h of incubation of 35 degrees C, 608 Listeria colonies from selected positive samples were biochemically confirmed as L. monocytogenes (245 isolates), L innocua (276 isolates), and L. welshimeri (89 isolates) and then ribotyped with the automated Riboprinter microbial characterization system (E. I. du Pont de Nemours & Co., Inc.). Thirty-six different Listeria strains comprising 16 L. monocytogenes (including four known clinical ribotypes), 12 L. innocua, and 8 L. welshimeri ribotypes were identified from selected positive samples (15 samples of each product type; two UVM and two LRB isolates per sample). Twenty-six of 36(13 L. monocytogenes) ribotypes were detected with both UVM and LRB, whereas 3 of 36 (1 L. monocytogenes) and 7 of 36 (3 L. monocytogenes) Listeria ribotypes were observed with only UVM or LRB, respectively. Ground beef, pork sausage, ground turkey, and chicken yielded 22 (8 L. monocytogenes), 21 (12 L. monocytogenes), 20 (9 L. monocytogenes), and 19 (11 L. monocytogenes) different Listeria ribotypes, respectively, with some Listeria ribotypes confined to a particular product. More importantly, major differences in both the number and distribution of Listeria ribotypes, including previously recognized clinical and nonclinical ribotypes of L. monocytogenes, were observed when 10 UVM and 10 LRB isolates from five samples of each product were ribotyped. When a third set of six samples per product type was examined from which two Listeria isolates were obtained by using only one of the two primary enrichment media, UVM and LRB failed to detect L. monocytogenes (both clinical and nonclinical ribotypes) in two and four samples, respectively. These findings stress the importance of using more than one primary enrichment medium and picking a sufficient number of colonies per sample when attempting to isolate specific L. monocytogenes strains during investigations of food-borne listeriosis.

Animals↗
PubMed1992

Beef and dressed chickens as sources of enterotoxigenic Staphylococcus aureus in Nairobi.

Staphylococcus aureus (S. aureus) isolates from beef carcasses, minced beef, and dressed chicken were assayed for production of enterotoxin A, B, C and D using reverse passive agglutination technique. The highest isolation rate was from chickens followed by minced beef. Chickens yielded the highest percentage of enterotoxigenic strains. Staphylococcal enterotoxin C (SEC) was the most frequently produced type from all the three sources while enterotoxin A ranked second and enterotoxin B third. These data show that chickens and minced beef are potential sources of food poisoning staphylococci in Kenya, and that increased handling of the products increases contamination suggesting that man is the major source.

Agglutination Tests↗
PubMed1992

Raw milk as a source of enterotoxigenic Staphylococcus aureus and enterotoxins in consumer milk.

Staphylococcus aureus strains were isolated from 183 of 300 raw milk samples collected at the Kenya Co-operative Creamery (Dandora). 97 of these 183 trains were assayed for the production of enterotoxin A, B, C and D. Seventy two (74.2%) of these were found to produce either a single or a combination of enterotoxins. Raw milk is a potential source of enterotoxigenic S. aureus in milk and milk products, especially if there is defective pasteurisation.

Animals↗
PubMed1990

Study of haemolytic activity of some Campylobacter spp. on blood agar plates.

A total of 152 strains of Campylobacter jejuni, C. coli, C. laridis and C. fetus subsp. fetus were tested for haemolysis on blood agar plates. Distinct haemolysis was detected in 92.3% (96/104) of strains of C. jejuni and 21.7% (5/23) of strains of C. coli on sheep blood heart infusion agar after incubation for 4 d microaerobically at 42 degrees C. Haemolysis was also detected on horse blood heart infusion agar. Haemolysis was not detected at 37 degrees C except with one of 50 strains of C. jejuni tested at this temperature, which was weakly positive. Campylobacter laridis was not haemolytic; C. fetus subsp. fetus, which does not grow at 42 degrees C, showed no haemolysis at 37 degrees C. Blood agar (Oxoid, BA Base No. 2) was not suitable for testing for haemolysis by these organisms. A microaerobic gas mixture containing hydrogen is better than that containing nitrogen because the medium has a brighter colour, making haemolysis easier to detect. There was no synergistic haemolysis with Staphylococcus aureus or Streptococcus agalactiae. The plate haemolysis test as described here may aid differentiation within the thermophilic campylobacters.

Animals↗
PubMed1989

Campylobacter infection in humans.

Campylobacter jejuni and Campylobacter coli are now recognized as common bacterial cause of enteritis in humans. They infect the healthiest of persons resulting in a self-limiting diarrhoea often accompanied by mucus and blood in the stool. On the other hand C. fetus subsp fetus attacks otherwise debilitated persons whose body defences have been weakened by underlying conditions, and causes extragastrointestinal campylobacteriosis. C. pylori, which is able to survive in the stomach acid environment, is now widely considered to be associated with gastritis, peptic ulcer, duodenal ulcer and non-duodenal ulcer, although its aetiologic role in the causation of the disease has not yet been established.

Campylobacter Infections↗
PubMed1988

Occurrence of 'thermophilic' campylobacters in sewage and their removal by treatment processes.

Removal of thermophilic campylobacters from sewage at three different stages of treatment at a trickling filter sewage works has been assessed. Samples of incoming sewage, primary sedimentation effluent and final effluent were taken daily from 06.00 h to 20.00 h for 5 consecutive days and the numbers of campylobacters determined by using a most probable number method. Each sample was cultured using 2 h pre-enrichment followed by enrichment in Preston broth for 48 h and detection by plating. Over 78% of the incoming campylobacters were removed after primary sedimentation and less than 0.1% remained in the final effluent. Campylobacter jejuni biotype I and biotype II constituted 81.5% and 15.9% respectively of the 232 isolates tested. Serotypes common in sewage were common in human faeces. It appears that the trickling filter sewage works removes most of the campylobacters entering the sewage works, but large numbers, estimated to be approximately 10(10), are released into the environment daily from a local sewage works.

Bacterial Typing Techniques↗