Fowl cholera

Abstract

Pasteurella multocida subspecies multocida is the most common cause of fowl cholera, although P. multocida subspecies septica and gallicida may also cause fowl cholera-like disease to some extent. However, the virulence properties of the different subspecies for various hosts have not been elucidated. The seventy and incidence of P. multocida infections may vary considerably depending on several factors associated with the host (including species and age of infected birds), the environment and the bacterial strain. No single virulence factor has been associated with the observed variation in virulence among strains. Possible virulence factors include the following: the capsule, endotoxin, outer membrane proteins, iron binding systems, heat shock proteins, neuraminidase production and antibody cleaving enzymes. No RTX toxins (repeats in toxin) appear to be produced by P. multocida, but P. multocida exotoxin (PMT) could contribute to virulence in some avian infections. The epidemiology of fowl cholera appears complex. Traditional serotyping systems are only of limited use in epidemiological studies. In recent years, molecular typing methods have been applied to avian strains of P. multocida of different origin. The results obtained using these newer methods indicate that wild birds may be a source of infection to commercial poultry. Documentation suggesting that mammals play a similar role is not as comprehensive, but the possibility cannot be excluded. Carrier birds seem to play a major role in the transmission of cholera. Surviving birds from diseased flocks appear to represent a risk, but more recent investigations indicate that carriers of P. multocida may exist within poultry flocks with no history of previous outbreaks of fowl cholera. The significance of this awaits further investigation.

Studies on the presence and persistence ofPasteurella multocidaserovars and genotypes in fowl cholera outbreaks

“…There are suggestions in the literature of reservoirs of P. multocida and the reintroduction into the flock from these sources, such as cats, pigs and wild birds (Serdyuk & Tsimokh, 1970;Glisson et al, 2003Glisson et al, , 2008Christensen et al, 2008).…”

An outbreak of chronic fowl cholera in broiler breeder chickens in Korea

“…The disease usually occurs in birds in two forms: an acute septicemia with high morbidity and mortality rates, and a chronic localized infection of joints and sinuses (Gilsson et al, 2003). Chronically infected birds are considered to be a major source of transmission and the most likely routes of FC transmission among birds are through direct contact or via contaminated water (Christensen and Bisgaard, 2000;Curtis and Ollerhead, 1981).…”

“…In domesticated birds, FC causes significant economic losses worldwide (Christensen et al, 2008;Gilsson et al, 2003). Turkeys and waterfowl are most affected, and death from FC in chickens usually occurs in laying flocks, because birds of this age are more susceptible than younger chickens (Gilsson et al, 2003).…”

“…Chronic FC is characterized by localized infections in the wattle, infraorbital sinus, sternal bursa, hock and wing joints, and foot pads. Chronic FC may follow an acute stage of the disease or result from infection with organisms of low virulence (Christensen et al, 2008;Gilsson et al, 2003;Timoney et al, 1992).…”

“…multocida is a gram-negative rod with bipolar staining that affects cattle (Frank, 1989), pigs (Blackall et al, 2000), rabbits (Langan et al, 2000), and humans (Weber et al, 1984), in addition to fowl (Christensen et al, 2008). P. multocida includes capsulated and noncapsulated types, with the former being more virulent than the latter (Boyce and Adler, 2000;Chung et al, 2001).…”