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 (40.5-41o 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 2nd 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
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.
