Sustainability of a Privatized Community-based Animal Health Worker System in Mwingi District,Kenya

This paper describes a study on the sustainability of Community-based Animal Health Worker (CAHW) services in Mwingi District, Kenya. These services began in 1992 and were supported by the District Veterinary Authority (DVA) with assistance from the Integrated Food Security Programme – Eastern (IFSP-E). Over time and using a process of participatory reviews with multiple stakeholders, the system evolved into a network of CAHWs. The study focused on CAHWs service sustainability and their relationships with other animal health service providers. A mutually beneficial and supportive arrangement existed between the CAHWs and Animal Health Assistants (AHAs), based on a private drug supply system, referral and backstopping support. The CAHWs derived sufficient income from their veterinary work to maintain their interest in the system. Seventy per cent of CAHWs were continuing to offer adequate animal health services 3 years or more after their initial training and the withdrawal of donor support. Ninety-five per cent of sampled CAHWs (n = 40) viewed their business as successful and expanding. Considering the agro-ecological and socio-economic conditions of the district, the CAHW system can be viewed as an initial stage in the process of extending quality private sector veterinary services.     

Assessment of the Technical Competence and Ethical Behaviour of Community-based Animal Health Workers in Mwingi District,Kenya

This paper describes an assessment of the technical competence and ethical behaviour of Community-based Animal Health Workers (CAHWs) in Mwingi District, Kenya. From 99 trained CAHWs, 40 participated in the study. Using a pre-tested semi-structured questionnaire, direct observation of the relevant veterinary drug kits and participatory discussions, the study team found that the CAHWs knowledge of clinical signs of local livestock diseases and notifiable and zoonotic diseases and their ability to use veterinary drugs correctly and safely were adequate. Marks were awarded to the candidates according to an agreed marking scheme between the CAHWs trainers and study team members. The results showed that, overall, 36 out of 40 (90%) of the sampled CAHWs passed the tests. The existence of a referral system for CAHWs and refresher trainings helped to ensure that CAHW competence and ethical behaviour were maintained. However, it was also found that some areas of the current curriculum required more detailed input based on field experience. The CAHW system could serve as an alternative animal health care system in areas lacking veterinary services.     

Development of PCR-based Detection Methods for the Quarantine Phytopathogen <Emphasis Type="Italic">Synchytrium endobioticum</Emphasis>, Causal Agent of Potato Wart Disease

PCR-based methods were developed for the detection and quantification of the potato pathogen Synchytrium endobioticum in soil extracts and in planta. PCR primers, based on the internal transcribed spacer region of the multi-copy gene rDNA were tested for specificity, sensitivity and reproducibility in conventional and real-time PCR assays. Soil extraction procedures compared included the Hendrickx centrifugation (HC) procedure, nested wet sieving (NWS) and a method used by the Plant Protection Service (PPS). The primers amplified a 472 bp product from S. endobioticum DNA, but did not amplify DNA from other potato pathogens, other plant pathogens, and related species. Standard cell disruption and DNA extraction and purification methods were optimized for amplification of S. endobioticum DNA from resting sporangia. DNA was successfully amplified from a single sporangium and equivalent DNA preparations from soil extracts. Low levels of target DNA in water did not amplify, possibly due to DNA loss during final purification steps. A real-time PCR assay, developed for soil-based extracts using primers and probe based on the rDNA gene sequences, involved co-amplification of target DNA along with an internal DNA fragment. Both conventional and real-time PCR methods performed well with HC- and NWS-extracts having a threshold sensitivity of 10 sporangia per PCR assay. Of the three soil extraction methods, only with the HC method could 100 g soil samples be efficiently processed in one single PCR assay. Such a high capacity assay could be useful for routine soil analysis in respect to disease risk assessments and to secure de-scheduling according to EPPO guidelines.     

Interspecies allometric analysis of the comparative pharmacokinetics of 44 drugs across veterinary and laboratory animal species

The purpose of this study was to apply the method of allometric analysis to a study of the comparative disposition of veterinary drugs using the Food Animal Residue Avoidance Databank (FARAD) as a source of the comparative pharmacokinetic data. An initial filtration of the FARAD data was performed in order to exclude drugs for which no pharmacokinetic data were available, in at least four species the route of administration was other than intravenous, and the matrix was different from blood, plasma or serum. This process restricted the study to a total of 44 candidate drugs. The primary pharmacokinetic parameter selected for study was half-life (t_1/2). As this parameter is a composite of clearance (Cl) and volume of distribution (Vd), it was considered to be the most robust for interspecies scaling. Volume of distribution at steady state (Vd_ss) and clearance showed weak allometric correlations with weight across species. The relationships between body weight and elimination half-life (t_1/2β) were determined for this selected group of drugs by using the empirically determined function Y=a W^b. The function Y represents the parameter of concern (half-life), a is a coefficient typical of every drug (intercept), W is the species average body weight, and b is the scaling exponent. A total of 11 drugs (tetracycline, oxytetracycline, chlortetracycline, erythromycin, diazepam, prednisolone, cephapirin, ampicillin, gentamicin, apramycin and carbenicillin) showed statistically significant correlations and consequently are excellent candidates for interspecies extrapolation of pharmacokinetic parameters (half-life) in species of relevance to veterinary medicine. The remaining 33 drugs were divided into two groups which showed various degrees of lack of correlation. Many of the drugs that showed no allometric correlation were low hepatic extraction drugs. However, some other drugs demonstrated equivocal results which could either be due to a true lack of allometric correlation, or be inconclusive due to the lack of quality data or excessive variability due to the multi-laboratory origin of the FARAD data. The results of this study show that interspecies scaling is applicable to certain veterinary drugs. The experimental determination of the coefficients of the allometric equation for relevant pharmacokinetic parameters (clearance and volume of distribution) could be an important tool in estimating dose in species where the drug has never been studied. This could have important consequences in terms of avoiding the use of dose-titration studies in Phase I of drug development, for drugs that are experimentally ‘well behaved’.     

Increased pulmonary secretion of tumor necrosis factor-alpha in calves experimentally infected with bovine respiratory syncytial virus

Bovine respiratory syncytial virus (BRSV) is an important cause of respiratory disease among calves in the Danish cattle industry. An experimental BRSV infection model was used to study the pathogenesis of the disease in calves. Broncho alveolar lung lavage (BAL) was performed on 28 Jersey calves, of which 23 were experimentally infected with BRSV and five were given a mock inoculum. The presence of the cytokine tumor necrosis factor alpha (TNF-alpha) in the BAL fluids was detected and quantified by a capture ELISA. TNF-alpha was detected in 21 of the infected animals. The amount of TNF-alpha in the BAL fluid of calves killed post inoculation day (PID) 2 and 4 was at the same very low level as in the uninfected control animals. Large amounts of TNF-alpha were detected on PID 6, maximum levels of TNF-alpha were reached on PID 7, and smaller amounts of TNF-alpha were seen on PID 8. The high levels of TNF-alpha appeared on the days where severe lung lesions and clinical signs were obvious and the amounts of BRSV-antigen were at their greatest. Although Pasteurellaceae were isolated from some of the BRSV-infected calves, calves treated with antibiotics before and through the whole period of the infection, as well as BRSV-infected calves free of bacteria reached the same level of TNF-alpha as animals from which bacteria were isolated from the lungs. It is concluded that significant quantities of TNF-alpha are produced in the lungs of the calves on PID 6-7 of BRSV infection. The involvement of TNF-alpha in the pathogenesis of, as well as the anti-viral immune response against, BRSV infection is discussed.     

Biofilm development within a larval rearing tank of the tropical rock lobster, Panulirus ornatus

The role of bacterial biofilms in disease processes is becoming increasingly recognised in both clinical and environmental settings. Biofilm development within a rearing tank of the tropical rock lobster Panulirus ornatus was studied to evaluate if the biofilm is a reservoir for potentially pathogenic bacteria that cause mass larval mortalities. Within a 5000 L larval rearing tank, fiberglass microscope slides were systematically distributed during a standard rearing attempt to assess biofilm development. Culture-based counts for two media types, TCBS and Marine Agar (MA), demonstrated increased bacterial densities until days 11 and 13 respectively. For both media types, a drop in the plate counts was followed by a subsequent increase towards the end of the experiment. Scanning electron microscopy (SEM) confirmed that cell densities decreased between days 13 and 17, most likely due to sloughing of the biofilm into the water column. SEM images revealed distinct changes in dominant morphologies reflecting a succession of bacterial populations. A dynamic succession of microbial species during biofilm development was also demonstrated using denaturing gradient gel electrophoresis (DGGE) profiling of bacterial 16S rRNA genes in combination with statistical ordination analysis. Prominent changes in the DGGE profiles coincided with the decrease in bacterial numbers observed by SEM and plating on MA between days 13 and 17. Fluorescence in situ hybridization (FISH) identified -Proteobacteria as being numerically abundant in the biofilm. This was supported by results from DGGE analysis, which retrieved only sequences affiliated with - and γ-Proteobacteria. DGGE bands affiliated with Vibrio became dominant towards the end of the larval run (days 21 to 24). A Vibrio harveyi strain isolated from the biofilm late in the larval rearing trial (day 24) demonstrated increased larval mortality in small scale phyllosoma survival studies. The detection of Vibrionaceae at the end of the larval trial coincided with mass phyllosoma mortality and show that the biofilm is a reservoir for potentially pathogenic bacteria.