Ephemeral Fever (Three Day Sickness)

Ephemeral Fever (Three Day Sickness) is also known as 3-day fever and Dragon Boat disease.

Bovine Ephemeral Fever (Three Day Sickness) is an insect borne non contagious viral disease of cattle, characterized by high fever, salivation and lameness.

Etiology

• Ephemeral fever virus is belongs to genus Ephemerovirus in the family Rhabdoviridae
• It is a single stranded negative sense RNA virus. There are number of strains that vary antigenically.
• The BEF virus is closely associated with the leukocyte-platelet fraction of blood
• The virus is inactivated at pH <5.0 and >10.0.

Epidemiology

• Ephemeral fever is enzootic in Africa, Asia, Middle East, East Indies and Australia.
• Morbidity rate: 100% in highly susceptible population under favourable environmental condition.
• Most cases are seen in the summer and early fall.
• Outbreaks often follows period of rainfall.
• In an enzootic area morbidity rate 5-10% and mortality rate 1%.

Host Affected

• Cattle and wild ruminants are highly susceptible
• All age group of cattle are susceptible and more common in animals less than 2 years of age.
• Calves less than 6 months old is not affected by the natural disease.

Transmission

• The disease is transmitted by mosquitoes during blood sucking.
• The disease can also be spread by intravenous inoculation of small amounts of blood.

Pathogenesis

• Virus multiplication primarly occur in vascular system.
• There is generalised inflammation with vasculitis and thrombosis, serofibrinous inflammation in serous and synovial cavities leads to increased endothelial permeability.

Clinical Manifestation

• Incubation period -2-4 days, sometimes as long as10 days
• Sudden onset of fever (40.5-41^o C)
• Anorexia
• Sudden fall in milk yield
• Serous nasal and ocular discharge
• Lacrimation
• Shivering
• Increased heart and respiratory rate
• Muscle stiffness, weakness in one or more limbs and lameness occur on 2^nd day 
• On  third  day of illness animal begins eating and ruminating and febrile reaction disappears, but lameness and weakness may persist for 2-3 more days
• Hypocalcaemia

Necropsy finding

• Serofibrinous polyserositis
• Pulmonary emphysema

Diagnosis

• Based on clinical signs
• Based on necropsy findings
• Leukocyosis
• Elevated level of plasma fibrinogen level for about 7 days
• Increased level of creatine kinase
• Hypocalcemia
• Serological test –blocking ELISA, SNT, CFT, FAT and AGID are used to identify antibodies

Differential diagnosis

• Botulism
• Parturient paresis
• Pneumonia
• Traumatic reticulitis

Treatment

• Non steroidal anti-inflammatory drugs phenylbutazone 8mg/ kg at 8 hours interval or ketoprofen 3mg/ kg b.wt once a day for three days.
• Calcium borogluconate should be given for cow shows hypocalcemia.
• Fluid therapy for dehydration.
• Provide complete rest.
• Recovered animal should not be stressed.

Control

• Vaccination.
• Live attenuated vaccine appear to be effective and should be used only in endemic area.
• Formalin inactivated killed vaccine is not effective.