Review of current problems and shortcomings in the Tanzanian animal health information system with suggestions on improvement

Livestock diseases have always been the focus of the Tanzanian Veterinary Authorities. However, they have become more important since the formation of the World Trade Organisation and subsequent implementation of the various multilateral agreements on trade. There is also a strong political desire to improve the animal health status as part of poverty alleviation strategies. As a result there is a need to develop better systems for investigating and reporting of animal diseases. In order to follow the OIE pathway and to obtain a disease free status, reliable evidence of freedom from particular diseases is becoming an issue of major interest. Assessment of the Tanzanian animal health information system revealed two major problems; firstly, the absence of disease information that accurately reflects the health status of the source population, and secondly, an inefficient information management system which is unable to provide useful information on the spatial component of animal health. A strategic approach is proposed that involves the collection of animal health information using active surveillance techniques and the introduction of a geographic information system. This approach should improve the management and reporting of animal health information.     

Domoic acid toxicity in Californian sea lions (Zalophus californianus): clinical signs, treatment and survival

Eighty-one Californian sea lions (Zalophus californianus) with signs of domoic acid toxicity stranded along the coast of California in 1998 when there were blooms of the domoic acid-producing alga Pseudonitzschia australis off-shore. In 2000, a further 184 sea lions stranded with similar clinical signs, but the strandings occurred both during detectable algal blooms and after the blooms had subsided. The clinical signs in these 265 Californian sea lions included seizures, ataxia, head weaving, decreased responsiveness to stimuli and scratching behaviour. Affected animals had high haematocrits, and eosinophil counts, and high activities of serum creatine kinase. They were treated supportively by using fluid therapy, diazepam, lorazepam and phenobarbitone. Fifty-five of the 81 sea lions (68 per cent) affected in 1998 and 81 of the 184 (44 per cent) affected in 2000 died despite the treatment. Three of the 23 sea lions which survived in 1998 were tracked with satellite and radiotransmitters; they travelled as far south as San Miguel Island, California, and survived for at least three months. Eleven of the 129 animals which were released stranded within four months of being released.     

Trends in antimicrobial susceptibility in relation to antimicrobial usage and presence of resistance genes in Staphylococcus hyicus isolated from exudative epidermitis in pigs

From 1996 to 2001 a total of 467 Staphylococcus hyicus isolates from exudative epidermitis (EE) in pigs in Denmark were examined for susceptibility to 13 different antimicrobial agents. The presence of selected genes encoding macrolide (erm(A), erm(B) and erm(C)), penicillin (blaZ), streptogramin (vat, vga, vga(B), vat(B), vat(D) and vat(E)), streptomycin (aadE) and tetracycline resistance (tet(K), tet(L), tet(M) and tet(O)) were determined in selected isolates.The occurrence of erythromycin resistance increased from 33% in 1996 to a maximum of 62% in 1997 and decreased to 26% in 2001. Resistance to sulphametazole increased from 17% in 1996 to 30% in 1998 but has since decreased to 4% in 2001. Resistance to trimethoprim increased to 51% in 1997 and decreased to 21% in 2001. Resistance to tetracycline (21-31%) remained relatively constant during 1996-2000, but increased to 47% in 2001. Resistance to penicillin (54-75%) streptomycin (33-53%) and tetracycline (21-47%) remained relatively constant over the time investigated.All 48 penicillin resistant isolates examined contained the blaZ gene and 40 (85%) of the streptomycin resistant isolates the aadE gene. It was not possible to detect any streptogramin resistance gene in four streptogramin resistant isolates. Of the 55 erythromycin resistant isolates examined, five contained erm(A), 13 erm(B), 35 erm(C) and two both erm(A) and erm(C). The presence of erm(B) was confirmed by hybridization to plasmid profiles in all 13 PCR-positive isolates. Of 52 tetracycline resistant isolates examined, two contained tet(L), 38 tet(K) and 12 both tet(K) and tet(L).     

Population changes in Phytophthora infestans in Taiwan associated with the appearance of resistance to metalaxyl

In recent years, late blight, caused by Phytophthora infestans (Mont) De Bary, has increased in severity in many parts of the world, and this has been associated with migrations which have introduced new, arguably more aggressive, populations of the pathogen. In Taiwan, late blight has been endemic on outdoor tomato crops grown in the highlands since the early 1900s, but recent epidemics have been more damaging. To ascertain the present status of the Taiwanese population of P infestans, 139 isolates of the pathogen collected and maintained by the Asian Vegetable Research and Development Center (AVRDC) were characterized using mating type, metalaxyl sensitivity, allozyme genotype, mitochondrial haplotype and RFLP fingerprinting. Up to 1997, all isolates were found to belong to the old clonal lineage of P infestans (US-1 and variants), but in isolates from 1998 a new genotype appeared, and by 2000 this had apparently completely displaced the old population. This new genotype was an A1 mating type and has the dilocus allozyme genotype 100/100/111, 100/100 for the loci coding for glucose-6-phosphate isomerase and peptidase, respectively. These characters, together with RG57 fingerprinting, indicated that these isolates belonged to the US-11 clonal lineage, a minority (11%) being a previously unreported variant of US-11. Whereas metalaxyl-resistant isolates were not detected in the old population, 96% of the new genotypes proved resistant, with the remainder being intermediate in sensitivity. It may be inferred from this sudden, marked change in the characteristics of the Taiwanese P infestans that a new population of the pathogen was introduced around 1997-98 and that this may well have already been metalaxyl-resistant when it arrived, although a role for in situ selection cannot be excluded.     

Retrospective study of the relationships between age, inflammation and the isolation of bacteria from the lower respiratory tract of thoroughbred horses

A total of 1235 tracheal aspirates taken from 724 thoroughbreds in race training, aged from two to 10 years, were examined cytologically and bacteriologically. An inflammation scoring system on a scale of 0 to 9 was devised to allow the severity of lower airway disease to be assessed from the cytological results. The inflammation scores were closely related to the isolation of bacteria (P<0.001), and the most common bacterial isolates were Streptococcus zooepidemicus, Streptococcus pneumoniae and Pasteurella/Actinobacillus-like species. Lower airway disease was less common in older horses (P = 0.031), and the groups at highest risk were the two- and four-year-olds. Lower airway inflammation was more common in the four-year-olds at National Hunt yards than in the four-year-olds at flat racing yards (P = 0.040, odds ratio = 3.80).     

Farmer record of pregnancy status pre-slaughter compared with actual pregnancy status post-slaughter and prevalence of gross genital tract abnormalities in New Zealand dairy cows

AIMS: To record the prevalence of gross abnormalities of the reproductive tract in culled New Zealand dairy cows, to determine how accurately farmers classify the pregnancy status of their animals and to establish if this was influenced by method of pregnancy diagnosis. METHODS: The reproductive tracts from 1134 cull dairy cows were examined after slaughter and evisceration for the presence of gross abnormalities, ovarian activity and pregnancy at a commercial abattoir. The farmers that had submitted these animals for slaughter were surveyed for information about the farm and herd from which each cow was derived and to establish whether the farmer believed each cow to be pregnant or not. The method that had been used to determine pregnancy status was recorded for each animal. RESULTS: Gross abnormalities were evident in 5.7% of reproductive tracts. Ovarian activity (presence of follicles 5 mm diameter and/or a corpus luteum) was apparent in 88% of non-pregnant cows. Pregnancy was detected in 39% of cows, of which 2.3% carried twins. The pregnancy status evident at slaughter varied from that reported by farmers in 7.0% of the 954 cows for which farmers were able to provide information. Of the cows that had been examined by palpation or ultrasound per rectum prior to slaughter, 10.3% that were recorded as non-pregnant by farmers were pregnant, and 3.2% of those recorded as pregnant were not. Of the cows that had not been examined, 3.8% of those recorded as nonpregnant by farmers were pregnant while 10.4% of those recorded as pregnant were not. There was no apparent association between gross genital tract abnormalities or ovarian activity and the misclassification of pregnancy status. Amongst cows that were pregnant at slaughter the foetus was significantly smaller in cows that had been recorded as 'not pregnant' after palpation or ultrasound examination than in cows that had been recorded as 'not pregnant' on the basis of farmer observation only. CONCLUSIONS: The prevalence of gross abnormalities of the reproductive tract was comparable to that reported in similar studies overseas. Farmer observation as a method of pregnancy detection overestimates pregnancy rate. Pregnancy status may be misclassified or misrecorded following palpation or ultrasound examination of cattle per rectum. Accurate classification of pregnancy status is dependent on the method and timing of pregnancy diagnosis and on minimising errors of diagnosis, cow identification and recording.     

Antimicrobial susceptibility and presence of resistance genes in staphylococci from poultry

The species distribution, susceptibility to 19 antimicrobial agents and presence of selected genes encoding resistance to macrolides, streptogramins and tetracyclines were examined among 118 staphylococcal isolates from infections of poultry in Denmark. Isolates were identified using a combination of conventional biochemical testing and 16S rDNA sequencing. The most common species were Staphylococcus aureus (83), Staphylococcus hyicus (11), Staphylococcus xylosus (9) and Staphylococcus cohnii (6). The isolates were susceptible to most antimicrobials tested. A high frequency of S. aureus (30%) was resistant to ciprofloxacin. Only six (7%) S. aureus isolates and one Staphylococcus saprophyticus were penicillin resistant. Resistance to sulphamethoxazole was observed among 16 (19%) of S. aureus isolates and two coagulase negative staphylococci (CNS). Twenty (24%) of the S. aureus isolates were resistant to erythromycin and 19 of these isolates contained the ermA gene, whereas the remaining isolate contained the ermC gene. Eleven (48%) of the novobiocin resistant CNS were resistant to erythromycin and all these isolates contained the ermA gene. Two isolates identified as S. xylosus, were found to be resistant to streptogramins and both contained the vatB- and the vgaB-genes. Thirty-nine (47%) of the S. aureus isolates, three of nine S. hyicus and eight of the 23 novobiocin resistant CNS were tetracycline resistant and all contained the tet(K) gene. A single S. aureus isolate also contained the tet(M) gene. The present study showed a frequent occurrence of resistance to fluoroquinolones, tetracycline and macrolides among staphylococci isolated from broilers in Denmark, whereas the occurrence of resistance to other antimicrobial agents remains low. Similar genes, encoding resistance to erythromycin, tetracycline and streptogramins to those previously observed, were detected.     

Distribution of peptidergic nerve fibres in the guinea pig trabecular meshwork

A quantitative analysis of peptidergic nerve fibres located in the trabecular meshwork of the guinea pig has been performed. Our results confirm that this structure contains VIP-, NPY- and substance P-like immunoreactivity as major neurotransmitters. These findings were obtained using immunohistochemical techniques. For this purpose serial sections of the eye were stained by immunohistochemistry for each of three neurotransmitters and stained sections were analysed by quantitative image analysis. Our findings demonstrate that SP-positive, NPY-positive and VIP-positive nerve fibres occupy 11.2, 4.9 and 2.4%, respectively, of the observed area (expressed as conventional units, C.U.) in the trabecular meshwork of the guinea pig eye. It is relevant to emphasize that the area containing these three types of peptidergic nerve fibres appears to be large (18.5 +/- 6.6 C.U.) in proportion to the total observed area. The innervation of the drainage angle of the guinea pig eye has been well described by many authors. This is the first study to report quantitative measurements of three types of peptidergic nerve fibres identified and measured in this area. The presence of these three neurotransmitters in the trabecular meshwork of guinea pig eye suggests their possible participation in aqueous humor regulation.