- Infectious Diseases of Livestock
- Part 3
- Moraxella spp. infections
- GENERAL INTRODUCTION: SPIROCHAETES
- Swine dysentery
- Borrelia theileri infection
- Borrelia suilla infection
- Lyme disease in livestock
- Leptospirosis
- GENERAL INTRODUCTION: AEROBIC ⁄ MICRO-AEROPHILIC, MOTILE, HELICAL ⁄ VIBROID GRAM-NEGATIVE BACTERIA
- Genital campylobacteriosis in cattle
- Proliferative enteropathies of pigs
- Campylobacter jejuni infection
- GENERAL INTRODUCTION: GRAM-NEGATIVE AEROBIC OR CAPNOPHILIC RODS AND COCCI
- Moraxella spp. infections
- Bordetella bronchiseptica infections
- Pseudomonas spp. infections
- Glanders
- Melioidosis
- Brucella spp. infections
- Bovine brucellosis
- Brucella ovis infection
- Brucella melitensis infection
- Brucella suis infection
- Brucella infections in terrestrial wildlife
- GENERAL INTRODUCTION: FACULTATIVELY ANAEROBIC GRAM NEGATIVE RODS
- Klebsiella spp. infections
- Escherichia coli infections
- Salmonella spp. infections
- Bovine salmonellosis
- Ovine and caprine salmonellosis
- Porcine salmonellosis
- Equine salmonellosis
- Yersinia spp. infections
- Haemophilus and Histophilus spp. infections
- Haemophilus parasuis infection
- Histophilus somni disease complex in cattle
- Actinobacillus spp. infections
- infections
- Actinobacillus equuli infections
- Gram-negative pleomorphic infections: Actinobacillus seminis, Histophilus ovis and Histophilus somni
- Porcine pleuropneumonia
- Actinobacillus suis infections
- Pasteurella and Mannheimia spp. infections
- Pneumonic mannheimiosis and pasteurellosis of cattle
- Haemorrhagic septicaemia
- Pasteurellosis in sheep and goats
- Porcine pasteurellosis
- Progressive atrophic rhinitis
- GENERAL INTRODUCTION: ANAEROBIC GRAM-NEGATIVE, IRREGULAR RODS
- Fusobacterium necrophorum, Dichelobacter (Bacteroides) nodosus and Bacteroides spp. infections
- GENERAL INTRODUCTION: GRAM-POSITIVE COCCI
- Staphylococcus spp. infections
- Staphylococcus aureus infections
- Exudative epidermitis
- Other Staphylococcus spp. infections
- Streptococcus spp. infections
- Strangles
- Streptococcus suis infections
- Streptococcus porcinus infections
- Other Streptococcus spp. infections
- GENERAL INTRODUCTION: ENDOSPORE-FORMING GRAM-POSITIVE RODS AND COCCI
- Anthrax
- Clostridium perfringens group infections
- Clostridium perfringens type A infections
- Clostridium perfringens type B infections
- Clostridium perfringens type C infections
- Clostridium perfringens type D infections
- Malignant oedema⁄gas gangrene group of Clostridium spp.
- Clostridium chauvoei infections
- Clostridium novyi infections
- Clostridium septicum infections
- Other clostridial infections
- Tetanus
- Botulism
- GENERAL INTRODUCTION: REGULAR, NON-SPORING, GRAM-POSITIVE RODS
- Listeriosis
- Erysipelothrix rhusiopathiae infections
- GENERAL INTRODUCTION: IRREGULAR, NON-SPORING, GRAM-POSITIVE RODS
- Corynebacterium pseudotuberculosis infections
- Corynebacterium renale group infections
- Bolo disease
- Actinomyces bovis infections
- Trueperella pyogenes infections
- Actinobaculum suis infections
- Actinomyces hyovaginalis infections
- GENERAL INTRODUCTION: MYCOBACTERIA
- Tuberculosis
- Paratuberculosis
- GENERAL INTRODUCTION: ACTINOMYCETES
- Nocardiosis
- Rhodococcus equi infections
- Dermatophilosis
- GENERAL INTRODUCTION: MOLLICUTES
- Contagious bovine pleuropneumonia
- Contagious caprine pleuropneumonia
- Mycoplasmal pneumonia of pigs
- Mycoplasmal polyserositis and arthritis of pigs
- Mycoplasmal arthritis of pigs
- Bovine genital mycoplasmosis
- Neurotoxin-producing group of Clostridium spp.
- Contagious equine metritis
- Tyzzer's disease
- MYCOTIC AND ALGAL DISEASES: Mycoses
- MYCOTIC AND ALGAL DISEASES: Pneumocystosis
- MYCOTIC AND ALGAL DISEASES: Protothecosis and other algal diseases
- DISEASE COMPLEXES / UNKNOWN AETIOLOGY: Epivag
- DISEASE COMPLEXES / UNKNOWN AETIOLOGY: Ulcerative balanoposthitis and vulvovaginitis of sheep
- DISEASE COMPLEXES / UNKNOWN AETIOLOGY: Ill thrift
- Eperythrozoonosis
- Bovine haemobartonellosis
Moraxella spp. infections
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Moraxella spp. infections
A VAN HALDEREN AND M M HENTON
Introduction
Of the known Moraxella spp., only Moraxella bovis, the cause of infectious bovine keratoconjunctivitis in cattle, is recognized as being an important pathogen of livestock.9 Moraxella bovis is also isolated from sheep suffering from keratoconjunctivitis on rare occasions, while Moraxella equi has been isolated from horses with keratoconjunctivitis.29 The role of Moraxella ovis in infectious ophthalmia in sheep and goats is uncertain, as it has also been isolated from the conjunctiva of healthy animals.9, 55 It has occasionally been associated with pneumonia and pleuritis in sheep and goats, and with pituitary abscesses in goats in South Africa. 27 Moraxella osloensis has been isolated from a lamb suffering from pneumonia, aborted calves, and from cattle with mastitis, while Moraxella phenylpyruvica has been associated with septicaemia in a calf and a sheep.9, 55 Moraxella caprae has been isolated from healthy goats and, although it may be biochemically similar to M. bovis, it can be distinguished by an inability to liquefy gelatin.33
Moraxella bovis infection
Infectious bovine keratoconjunctivitis caused by M. bovis is characterized by lachrymation, conjunctivitis and keratitis.5, 43 It has been described under a variety of names including New Forest disease, pink eye, blight, and infectious keratitis. 43 This condition was first described as keratitis contagiosa by Billings in the USA in 1889, and has subsequently been reported throughout the world and in many countries is regarded as an important economic disease.5, 11, 26, 43
Moraxella bovis is generally accepted as being the primary cause of infectious ophthalmia of cattle.3, 6, 27, 36, 38, 43–45
Aetiology
Moraxella bovis is a non-motile, non-sugar fermenting, Gram-negative, short and plump diplobacillus.50 Different strains of M. bovis, which vary in virulence, occur,5, 30 but only haemolytic,6, 37, 43–45 piliated or fimbriated30, 43–45 strains are pathogenic. Various types of pili have been described, and each is associated with the production of specific antibodies. 48 Pili have been arranged in seven groups (A–G) in a unified pili serotyping scheme.39 The production of certain enzymes, such as lipases and proteases,30, 44, 45 and the presence of a dermonecrotic toxin7, 44, 45 also play an important role in the virulence of M. bovis. The ability of M. bovis to change spontaneously from virulent to avirulent strains in vivo and in vitro43, 50 may be the reason why many transmission experiments have been unsuccessful. Phase variation, which is a reversible genetic mechanism, controls pilus expression. 30, 36 Much confusion surrounds the description of colony morphology with regard to piliated or non-piliated strains — both kinds having been variously described as rough or smooth.5, 30, 37, 38, 43, 50
Epidemiology
Infectious bovine keratoconjunctivitis is highly contagious and usually occurs in epidemics; individual cases are rare.5, 43 The prevalence in a herd may vary from 10 to 76 per cent,26 but although the morbidity rate is high, the mortality rate is negligible.7 The disease is more common and usually more severe in young animals,7, 32, 53, 56 although previously unexposed adult cattle may be affected.56 There are definite breed differences in susceptibility — the Hereford and its crosses appear to be most susceptible although Channel Island breeds, Aberdeen Angus and Charolais also appear to be highly susceptible,11 while the Bos indicus breeds are least susceptible.5, 43, 51, 56, 57 Animals having pigmented skin around the eye are more resistant to infection.
Clinically healthy carrier animals harbour the organism in the oculonasal tract,36, 37, 42 and play an important role in maintaining the infection.7, 32, 38, 42, 43 They may be responsible for introducing the disease into previously clean herds.51 Transmission may be either direct, by means of droplet infection from oculonasal secretion,35, 42 or indirect by insect carriers such as the house fly (Musca domestica), face fly (Musca autumnalis) or stable fly (Stomoxys calcitrans)5, 11, 25, 35, 43 (see Vectors: Muscidae.) Moraxella bovis has been transmitted experimentally by Musca autumnalis4, 23 and by Arcyophora longivalvis, a moth that feeds on the ocular secretion of cattle. Other eyefrequenting Lepidoptera have also been implicated in southern Africa as possible transmitters of M. bovis and other micro-organisms of the eyes.14–16, 26
Infectious ophthalmia is most prevalent during the summer months,6, 42, 51, 56 as dust and other mechanical irritants, increased ultraviolet radiation, increased fly populations, and crowding of animals predispose to the infection, 5, 6, 12, 19, 35–37, 42, 51 while vitamin A deficiency has also been suggested as a possible predisposing factor.5, 43 Stress such as transport may aggravate the disease,42 as may concurrent or prior infection with other infectious agents such as Chlamydophila pecorum, infectious bovine rhinotracheitis, parainfluenza-3 and adenoviruses as well as certain Mycoplasma spp.1, 6, 11, 43, 46, 47 The infection does not appear to be transmitted from cattle to sheep.26
Pathogenesis
Pathogenic strains of M. bovis have the ability to adhere to and penetrate the superficial epithelial cells of the cornea and conjunctiva. Adhesion appears to...
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