Indirect haemagglutinating antibody in the nasal pharyongeal carriers of Pasteurella haemolytica

Abstract

In an assessment of the carrier rate and population of Pasteurella haemoltyica in sixteen housed, goats by cultural examination of nasopharyngeal swabs the organism was demonstrated in nine animals, the majority of isolates proving untypable by the indirect haemagglutination (l.H.) serotyping procedure. The spectrum and levels of I.H. antibody to P. haemolytica serotypes A₁, A₂, T₃, T₄, A₇, A₉,T₁₀, A₁₁ and A₁₂ in nasal secretions and serum were determined.

Changes in these parameters with time were assessed by regular examination of eight normal goats, and of seven others whilst under conditions of increased environmental relative humidity and temperature.

A low incidence of low titre I.H. antibodies to a spectrum of serotypes and independent of serum titres was demonstrated in nasal secretions of both carrier and non-carrier goats, and in carriers irrespective of the numbers of P. haemolytica isolated. While in some non-carriers relatively high nasal titres to A₆ serotype were maintained throughout the observation period, the demonstration of nasal antibodies was in the main sporadic.

Serum I.H. titres, as well as the pattern of nasopharyngeal carriers remained relatively stable throughout the observation period. No effect of altered environmental conditions was demonstrated.

A nasopharyngeal carrier state was established by the intranasal inoculation of a single goat with a known P. haemolytica serotype. Nasal I.H. antibodies to 4 serotypes were demonstrated 22 days later while serum I.H. antibody titres remained stable.

Comparison between goats and sheep of the spectrum and levels of I.H. antibody to P. haemolytica serotypes showed in the latter species higher I.H. titres in both nasal secretions and serum, as well as a higher incidence of consistently demonstrable nasal antibodies to serotypes A₂, A₆, A₇, A₉,T₁₀ and A₁₁. For two serotypes correlation of nasal with serum antibody concentrations was demonstrated, but little relationship was shown between specific nasal antibodies and P. haemolytica serotypes isolated.

In an examination in eight sheep of the effect of experimental Tick-borne fever infection on the nasopharyngeal P. haemolytica population and on nasal and serum I.H. antibody levels, an increased isolation rate was demonstrated ten days post-infection with evidence of an associated rise in nasal I.H. titres to those serotypes carried.