Picornaviruses: rapid differentiation and identification by immune electronmicroscopy and immunodiffusion.

Immune electronmicroscopy (IEM) was used to identify human picornaviruses rapidly and to differentiate enteroviruses from rhinoviruses. Human sera, diluted 10- to 50-fold beyond the neutralisation endpoints for homologous virus, readily agglutinated C-type antigens of seven human picornaviruses. Human sera did not react by IEM with a control animal picornavirus. By IEM after acid treatment, differentiation of a human enterovirus from a human rhinovirus was possible. There was an excellent correlation between the results of IEM and immunodiffusion (ID) tests for the presence of antibody to human picornavirus group antigens. By ID, only one of 21 human sera reacted with one of six animal picornaviruses. Immune electronmicroscopy appears to be a sensitive and simple techinque for the detection of picornavirus C-type antigens, and may be useful for identifying viruses belonging to groups comprising many serotypes and sharing a common group antigen.

Composition of a polysaccharide from mycoplasma (F-38) recognised by antibodies from goats with contagious pleuropneumonia.

A polysaccharide was extracted by warm aqueous phenol from the F-38 strain of mycoplasma which causes contagious caprine pleuropneumonia (CCPP). After acid hydrolysis, the polysaccharide was found to be composed of the neutral sugars glucose, galactose, mannose and fucose and the amino sugars galactosamine and glucosamine. All the sugars were present in approximately equal quantities. Unmodified goat erythrocytes bound the polysaccharide readily and the sensitised cells reacted with antibodies in sera from goats with experimental or natural CCPP. The unique composition of the F-38 polysaccharide and the specific reactivity of polysaccharide-sensitised red cells with antibodies from CCPP infected animals suggests that the polysaccharide should be useful for identification of F-38 organisms and diagnosis of the disease.

Kenya: the development of private services and the role of the Kenya Veterinary Association.

Private veterinary practice has existed in Kenya for more than half a century. Between the early 1930s and the mid-1960s, provision of clinical and advisory services almost entirely involved servicing commercial ranches and dairy farms. The Department of Veterinary Services (VSD) was mainly responsible for providing regulatory services in these areas. Until the mid-1960s, public sector veterinary responsibilities were predominantly associated with the prevention of notifiable diseases outside the commercial farming areas. In a major agrarian reform programme initiated in 1954, Kenya initiated an aggressive campaign promoting the dairy industry in the wetter areas of the country among small-scale farmers. In an effort to encourage dairy development, the VSD decided to provide some services, mainly tick control and subsidised artificial insemination. This support had a great positive impact on the 'smallholder' dairy industry. After the end of the colonial administration in 1963, most private practitioners left the country. A decision was therefore taken to transfer the responsibility of providing services of a 'private goods' nature, such as clinical services, temporarily to the public sector through the VSD. This was accompanied by significant expansion of training and the deployment of both professional veterinarians and para-professionals. By 1988, personnel costs had escalated to over 80% of the recurrent budget, leaving little for operational costs. This necessitated a policy change, which led to decreased government involvement in the delivery of animal health services. The private sector, as expected, responded appropriately to the change in policy. The Kenya Veterinary Association (KVA) launched a privatisation scheme (the Kenya Veterinary Association Privatisation Scheme) in 1994 to provide members with credit to set up private practices. The first phase of the scheme (1994-1996) was rated a success, with 100% loan repayments. The second phase of the project (from 1997) was characterised by a low number of loan applications, which increased the cost of loan administration per unit. There was some defaulting in loan repayments during this phase. While private veterinary practice took root in the high rainfall, intensive farming areas, this was not the case in the arid and semi-arid lands (ASAL), where community-based animal health workers (CAHWs) played a prominent role in providing animal health services. The lack of uniformity in the training of these workers denied them recognition by the Kenya Veterinary Board (KVB). An agreement has now been reached between the KVB, the Director of Veterinary Services and the KVA to discontinue the training of CAHWs and to retain and retrain existing workers for disease surveillance and reporting in ASAL areas. In conclusion, private veterinary practice has been successful in areas of high agricultural potential. Expansion to more marginal areas, however, would require incentives or subsidies.

A latex agglutination test for field diagnosis of contagious caprine pleuropneumonia.

Latex beads were sensitised with a polysaccharide isolated from a F38 culture supernatant and used in a slide agglutination test to detect serum antibodies in goats with contagious caprine pleuropneumonia. The latex agglutination test detected antibodies in the sera of goats by 22 +/- 2 (mean +/- 1 sd) days after contact exposure to contagious caprine pleuropneumonia, whereas the complement-fixation test detected antibodies by 24 +/- 4 days after contact exposure. Both tests were negative with 181 sera from a farm which was free of the disease. When the same tests were done on 763 sera from two different farms with outbreaks of classical contagious caprine pleuropneumonia, 63 per cent were positive by the latex agglutination test and 23 per cent were positive by the complement-fixation test. Besides being more sensitive than complement fixation, the latex agglutination test can be performed in the field using undiluted serum or whole blood and a result obtained within two minutes.

An inactivated vaccine for contagious caprine pleuropneumonia.

The results from several experiments demonstrated that an effective vaccine for contagious caprine pleuropneumonia could be made with inactivated F38 mycoplasma. Evaluation of the amounts of lyophilised F38 mycoplasma plus saponin showed that the optimum formulation was 0.15 mg of mycoplasma in saponin. Saponin inactivates the mycoplasma and provides the adjuvant effect necessary to stimulate a protective immune response. The lyophilised F38 mycoplasma could be stored for 14 months at either 4 degrees C or 22 degrees C without losing its immunising potential. A single immunisation with the optimum formulation produced a protective immune response in goats that lasted for longer than one year.

Re-emergence of rinderpest as a threat in East Africa since 1979.

Following the success of the JP15 scheme and subsequent annual vaccination campaigns, East Africa was virtually free of rinderpest after the mid 1960s and the disease was considered beaten. However, economic difficulties have recently reduced the expensively maintained vaccine cover and the disease has reappeared throughout much of the region. In 1979 rinderpest was diagnosed in cattle in north eastern Uganda and caused considerable losses until finally brought under control in 1981. No field outbreaks of the disease in cattle have been seen in Kenya but there is serological evidence that the virus has recently infected unvaccinated sheep and goats and wild ungulates in that country. In 1982 rinderpest was confirmed in the laboratory as the cause of death of large numbers of buffaloes in northern Tanzania and implicated as the cause of a rinderpest-like disease of cattle which is reported to be still active in that area. Substantial aid is essential for further control and research if the virus is not again to become endemic in the region.

Clinical trial of halofuginone lactate for the treatment of East Coast fever in Kenya.

A field trial was undertaken to test the efficacy of halofuginone lactate in the treatment of East Coast fever under farming conditions in Kenya. The drug was administered orally at a dose of 1.2 mg/kg bodyweight and treatment was repeated after 48 hours. Of 293 cases treated 236 (80.5 per cent) recovered and 49 (16.7 per cent) died. Five animals were disposed of by the owners and three became chronically infected. No differences were recorded in recovery rate between uncomplicated cases and cases with concurrent anaplasmosis or babesiosis, nor were there any significant differences in recovery rates between animals of different types. However, zebu cattle (Bos indicus) tended to respond more rapidly to treatment than exotic cattle (Bos taurus). Younger animals had a poorer recovery rate than adults. Early treatments were more successful than those administered late. It was concluded that with early detection and treatment, coupled with efficient tick control, halofuginone lactate is effective in the treatment of clinical East Coast fever under field conditions.

Vaccination against contagious caprine pleuropneumonia caused by F38.

Only F38 isolates of mycoplasma cause classical contagious caprine pleuropneumonia (CCPP). Therefore, research has focused on the development of a vaccine that will prevent serious epidemics of the disease in goats. Goats immunized with two doses of a lyophilized preparation of isolated F38 organisms administered 4 weeks apart were completely immune to experimentally induced CCPP. The minimum immunizing dose was 0.15 mg, and this dose was still effective after storage for 14 months at 4 C and 22 C. The duration of immunity induced by a single dose of lyophilized F38 was at least 12 months.