Prepared by:

DR. HUSSEIN HOSINY HUSSEIN HASSANIN
LECTURER OF POULTRY DISEASES
2000 EGYPT

Introduction

Avian salmonellosis is an inclusive term designating a large group of acute or chronic diseases of fowl caused by any one or more members of the genus salmonella, which is included in the large family Entrobacterriaceae (Hofstad et.al.1984).
The genus salmonella, named for the late element USDA veterinarian Daniel E. Salmon , is composed of more than 1800 serologic types, each with a specific serotype name (Hofstad et. At.1984).

Calnek-BW et.al.(1997) and saeed-AM , (1998) reported that there are more than 2300 members of the genus salmonella that can be recognized as separate serovars or serotypes.
Ecologically, these serotypes can be divided into host-adapted and non-host adapted groups (McCoy,1975; Clarke and Gyles, 1993).

Most serotype designations have been derived from places where organisms were first isolated, resulting in names representative of worldwide centers of populations. The rapidity with which new types have been added to the everexpanding list of salmonella is illustrated by the fact that only about 60 types were recognized in the 1943 edition of this book (Hofstad et al., 1984).
Since the 1940’s there has been a rapid increase in the isolation of the non-host specific Salmonella Serovars from humans and animals (Gurthie, 1992).
In the U.S., during the past three decades, the number of culture-confirmed salmonella infections has steadily increased (Altekruse et.al., 1993).

There were 26,326 in 1972 compared to 39,032 reported cases in 1996 representing 47% increase during this 26 year period; much of the increase in Salmonella isolations has been due to the increase in isolates of S. enterifidis which was rated at 459 percent during this period, while all other serotypes increased by only 18 percent; among other common serotypes (Angulo and Swerdlow., 1998) proposed that the genus Salmonella be divided into 4 subgenera varying in their biochemical reactions on diagnostic medi.

This division has been adopted; by the 8th edition of Bergey’s Manual. Under it the great majority of Salmonella serotypes bear species like epithets and are included in subgenus 1. New types belonging to subgenera II, III, and IV described after 1966 are; designated; simply by formula.

Although recent taxonomic refinements have indicated that all salmonella can be grouped into only five subgenera, the distinction between serotypes are often epidemiologically relevant. Accordingly, Salmonella isolates are still; most often described primarily in terms of their traditional serotype nomenclature. (Calnek et al., 1997).
Salmonellosis is a persistent worldwide problem, It has been associated with marketing difficulties, economic losses), and lowered performance.

Domestic poultry constitutes the largest single; reservoir of Salmonella organisms existing in nature. Among all animal species the Salmonella are most frequently reported from poultry and poultry products, partly because of the large population at risk and the active nationwide programs for their isolation and identification (Hofstad et al., 1984).

Poultry and poultry products have been the main sources of non-host specific Salmonella infecting humans.

The avian species, environment, and rodents were among the major reservoirs of S. enteritidis. Eggs are the dominant source of S. enteritidis infections in humans as indicated by the investigations of many outbreaks and sporadic cases. According to numerous search reports, The spread of S.enteritidis can be largely due to the phenomenon of transovarian transmission of the organisms which leads to the contamination of eggs internally. The ability of this Salmonella serovar to infect the hen's ovary is propably related to its similarity to S. pullorum and S. gallinarum. However, it seems that S.

enteritidis has developed a more peaceful relationship with its avian host since it does not cause an overt disease in hens as its relative serovars do. This can be regarded as a process of adaptation by the organism to a host that been made available due to the increased intensity of production during the past three decades (Saeed-AM, 1998).

With the great expansion of the poultry industry, the; widespread occurrence of avian Salmonellosis has ranked it as one of the most important egg borne bacterial diseases of poultry. As these infections recognize no international boundaries and few host barriers, nationwide programs to control them have been beset with numerous obstacles.

Avian Salmonellosis is a problem of economic concern to all phases of the poultry industry from production to Marketing. Pet store owners, Zoological Park administrators, pigeon and fancy bird raisers, and those interested in wild game are also concerned with these diseases (Hofstad et al., 1984) .
The dimensions of the poultry Salmonella problem have expanded considerably in recent years. In the past, the primary motivation for controlling Salmonella infections in poultry was to reduce disease losses.

Today, public health concerns, political pressures, and consumer demands have increasingly made prevention of food-borne transmission of disease to humans on urgent priority for poultry producers. Pullorum disease and fowl Typhoid have been attacked effectively in the United States by a strategy of testing and eradication.
The paratyphoid Salmonella, however, are not host specific and are found nearly ubiquitously in domestic animals, wild animals, and humans.

In addition, the international scope of the modern poultry industry has created new and more complex opportunities for the spread of Salmonella with so many potential sources of introduction of paratyphoid Salmonella into poultry flocks, the strategy for controlling these organisms may have to be correspondingly broader than has been applied to the avian-adapted serotypes.

The combined application of an array of control measures, including testing programs, the production of Salmonella-free feed, the elimination of biological vectors (pests), effective cleaning and disinfection of poultry houses, and prophylactic treatment of poultry to reduce their susceptibility to infection, may be necessary to achieve tangible progress in reducing the overall incidence of Salmonella in poultry and poultry products (Calnek et. Al., 1997).

According to Hofstad et al. (1984) and Calnek et al. (1997),. Infection of poultry with Salmonella can be classified into three categories, each of which will be the subject of a separate section. The first section, discusses the two non motile serotypes, S. pullorum and S. gallinarum, which are generally host-specific for avian species. Pullorum disease caused by S. pullorum, is an acute systemic disease of chicks and poults.

Fowl typhoid, caused by S. gallinarum, is an acute or chronic septicemic disease that mostoften affects mature birds. Both of these diseases have been responsible for serious economic losses to poultry producers in the past, and have been addressed by the implantation of extensive testing and eradication programs.

The second section discuss infections with a group of motile salmonella serotypes referred to collectively as Paratyphoid salmonellae. This diverse group of serotypes is principally of concern as a cause of food–born disease in humans. Although paratyphoid infection of poultry are very common, they seldom cause acute systemic disease except in highly susceptible young birds subjected to stressful condition.

More often paratyphoid salmonella infections of chickens and turkeys are characterized by a symptomatic colonization of the intestinal tract, sometimes persisting until slaughter and leading ultimately to contamination of the finished carcass. Some serotypes, especially S.
enteritides, can be deposited in the contents of clean and intact eggs. Improper food handling before consumption can permit the multiplication of salmonella to levels capable of causing severe gastrointestinal disease in human consumers.

Heightened concerns about the microbial safety of foods have led to the initiation of numerous testing efforts to detect Paratyphoid salmonella in poultry flocks and poultry products.

The third section discusses infections with the various motile serotypes of the subgenus s. arizonae, which was formerly designated Arizona hinshawii .This group of organisms, although biochemically distinct, causes a disease that is not clinically distinguishable from other salmonella infections. Arizonosis is of particular economic significance in turkey.

In the present review, some of the most recent as well as some historical and basic published reports and research reprints was collected and summarized, to highlight the most recent applicable information about Avian Salmonellosis, under the following tittles:

• Avian Salmonellosis; general
• Avian Salmonellosis in Egypt
• Pullorum Disease and Fowl Typhoid
• Salmonella Typhimurium Infections
• Salmonella Enteritidis Infections
• Avian Arizonosis
• References