Malignant catarrhal fever (cause, symptoms, treatment)

Synonyms: Bovine malignant catarrh, Malignant head catarrh, Catarrhal fever, Epitheliosis

Introduction

• Malignant catarrhal fever (MCF) is a fatal disease of cattle characterized by catarrhal inflammation of the nasal and oral mucosa, keratoconjunctivitis, encephalitis, rapid dehydration, and generalized enlargement of lymph nodes.
• The disease is usually sporadic.
• The disease is worldwide in distribution and prevalent in both temperate and tropical zones.

Etiology

• This disease is caused by ovine herpes virus -1 and alcelaphine herpesvirus- 2 which are belonging to the family Herpesviridae.
• The disease is primarily a disease of cattle and buffalo. The inapparent infection in sheep and goats is also prevalent.

Transmission

• This disease is transmitted through wild beasts.
• The wild beast develops viremia which may persist up to 3 months and during that time they remain highly infective for cattle of all ages.
• Cattle acquire the infection through subclinically affected sheep.
• The sheep are the indicator host and wild rabbits are the reservoir host for MCF.

Clinical signs

• The incubation period of the disease ranges from 2-8 weeks.

1. Peracute form:

The high rise of temperature, dyspnoea, and diarrhea but without any head and eye lesions

2. Head and eye form:

The clinical course of around 9 days characterized by nervous syndrome-like paralysis and convulsion before death

3. Intestinal form

4. Inapparent (mild) form

The disease shows following symptoms;

• Dullness, depression, anorexia, and high rise of temperature ranging from 105-108ºF.
• Oocular and nasal discharge.
• Discharges are initially mucoid which soon become mucopurulent, stingy, and contain blood flecks.
• There is an acceleration of pulse and respiratory rate.
• Signs of dyspnea may be evident.
• Edema of the eyelids leading to panopthalmitis
• Changes in the epithelium of the mouth cavity comprising of congestive changes, precisely on the gum, beneath the tongue, hard palate, and oral papillae.
• Erosive and ultimate necrotic changes may follow in the oral mucosa giving rise to offensive odor from the mouth.
• Ocular lesions– Photophobia and meiosis, corneal opacity, blindness
• Cutaneous lesions (congestion, petechiation, bluish discoloration, and thickening) localized or generalized prominent on the muzzle, skin of the hoof, scrotum, base of the horn, and teat.

Diagnosis

• Based on clinical signs
• No reliable serological or immunological tests

Differential diagnosis

• Rinderpest
• Mucosal disease
• Infectious bovine rhinotracheitis

Prevention and control

• Inactivated or live vaccines with suitable adjuvants induce antibodies against MCFV.
• In the absence of a vaccine, the only effective strategy is to limit contact between MCF susceptible species and the natural hosts of the virus.
• Sheep is a spreader of field outbreaks. Therefore, a rigid separation of cattle from sheep is must.
• The feed used by ewes and lambs should not be provided to cattle.
• Avoid contact between reservoir host (wildebeest and wild rabbits) and cattle

Source: repository.up.ac.za