| dc.description.abstract | The potential of village chickens in Kenya has not been fully exploited because
most farmers do not practice disease control, supplementation, and there is no
proper housing for the birds. Control of viral diseases especially Newcastle
disease which is one of the major setbacks for village chicken farmers has not
been dealt with. This work was designed to find out which strains of Avian
paramyxovirus (APMV) occurred in the rural chickens and wild birds and if
these chicken and wild birds could be potential reservoirs of virulent Newcastle
disease virus (NDV). Field samples (cloacal and whole blood) were collected
from live market village chickens at the time of slaughter. The samples were
processed for virus isolation and the isolates recovered characterized using their
haemagglutination-elution patterns, receptor specificity for red blood cells from
different animal species, haemagglutinin thermo stability, virulence in 9-day old
embryonated eggs, cross reactivity of the isolates among themselves and control
strains tested by the haemagglutination inhibition (HI) test with homologous and
heterologous and reference sera for paramyxovirus serotypes APMV -1 to
APMV-9. One hundred and sixty two avian paramyxovirus serotype-1 (APMV-
1) and one avian paramyxovirus serotype-4 (APMV-4) were isolated from the
rural chickens and wild birds composed of one hundred and forty six isolates
from chicken, eleven from wild birds, five from Lake Bogoria water and one
(APMV-4) from flamingo faeces. Haemagglutination-elution patterns showed
that of the isolates recovered, 13 were fast eluters, 10 were moderate eluters, 41
were partial and 23 were non-eluters at 4°C. Elution appeared unrelated to any
aspect of the virus history or other virus character. Receptor specificity of the
isolates regarding red blood cells from seven species showed that all virus
isolates agglutinated chicken red blood cells and in addition, dog red blood cells
were agglutinated by most NDV isolates. Thermostability of haemagglutination
activity of the isolates showed that at 56°C all the isolates were inactivated within
8 hours. Of the twenty-one NDV isolates tested for virulence, 10 were velogenic,
7 were meso genic and four were lentogenic. Flocks with velogenic strains
constitute a reservoir of virulent Newcastle disease virus and this could be a
potential danger to the chicken industry. The NDV isolates showed antigenic
differences; however 8 pairs showed no cross-reactivity, 3 pairs of isolates were
slightly related asymmetrically, and 33 pairs showed one-sided moderate
relationship. Some vaccine strains were reacting asymmetrically with some of the
isolates i.e. antisera against LaSota and F-strain vaccine strains could not
neutralize B26, K2 and KII virus isolates. Serology served as a useful diagnostic
function allowing detection of infections in unvaccinated flocks and also an
indication of exposure. Three hundred and eighteen samples were screened and
87 serum samples were positive and some showed cross-reactivity with the
APMV-2 to APMV-9. After adsorption of the antisera with NDV-L, only
APMV-3 showed specific haemagglutination inhibition against B37, WI, WI7,
KRI39 and B6, the other inhibitions against the other APMV isolates were crossreactions
indicating the possibility that PMV-3 occurred in village chickens.
NDV is widespread throughout Kenya. It was concluded that velogenic NDV
strains are widespread in village chickens sold through live bird markets. Such
birds are a reservoir of and can spread velogenic NDV and be a danger to the
poultry industry. Wild birds harboured virulent NDV and pose danger to the
poultry industry. | en |
