Three-Day Sickness (Bovine Ephemeral Fever) in Cattle

- Acknowledgment

We would like to acknowledge the committee of the National Egyptian Guidelines for Veterinary Medical Interventions, Egyptian Health Council for adapting this guideline.

Executive Chief of the Egyptian Health Council: Prof. Mohamed Mustafa Lotief.

Head of the Committee: Prof. Ahmed M Byomi

The rapporteur of the Committee: Prof. Mohamed Mohamedy Ghanem.

Scientific Group Members: Prof. Nabil Yassien, Prof. Ashraf Aldesoky Shamaa, Prof. Amany Abbas, Prof. Dalia Mansour, Dr Essam Sobhy Dr Mohamed Elsharkawy, Prof. Dr Gamal A. Sosa., Dr Naglaa Radwan, Dr Hend El Sheikh

Editor/Author: Prof. Mohamed Ghanem

- Definition

Three-day sickness, also known as Bovine Ephemeral Fever (BEF), is an acute febrile viral disease affecting cattle and water buffalo. The disease is characterized by sudden onset of high fever, stiffness, lameness, muscle tremors, depression, nasal discharge, and a marked reduction in milk production. The disease is generally self-limiting, with most animals recovering within approximately three days, which explains the common name “three-day sickness.”

- Economic importance

Bovine Ephemeral Fever is considered one of the economically important arthropod-borne viral diseases of cattle in tropical and subtropical regions. Outbreaks may result in significant economic losses due to decreased milk yield, loss of body condition, reduced draft power, infertility, abortion in severe cases, and occasional mortality.

- Etiology

Bovine Ephemeral Fever is caused by the Bovine Ephemeral Fever Virus (BEFV), which belongs to:

Order: Mononegavirales. Family: Rhabdoviridae, Genus: Ephemerovirus

The virus is Enveloped, Bullet-shaped, Single-stranded negative-sense RNA virus

The virus is sensitive to: Heat, Lipid solvents, Detergents, and Disinfectants

However, it survives for short periods in blood and vectors.

- Geographic Distribution

The disease occurs mainly in Africa, Middle East, Australia, and Asia

Outbreaks are commonly associated with warm seasons and increased insect vector activity.

- Transmission

Vector-Borne Transmission

BEF is transmitted primarily through blood-feeding arthropods.

Important vectors include:

Mosquitoes (Culex and Aedes species) - Culicoides biting midges

Factors Favoring Transmission

Warm temperatures

High humidity

Heavy rainfall

Presence of standing water

Large vector populations

Direct transmission between animals is considered insignificant.

- Susceptible species

Cattle and water buffalo are the highly Susceptible

Sheep and goats are usually resistant.

Morbidity

Morbidity may range from 30–100%.

Mortality

Mortality is usually low (1–2%). Increasing mortalities could occur in:

·       High-producing dairy cows

·       Pregnant animals

·       Bulls

- Seasonal Occurrence and risk facotors

The disease commonly occurs during summer and early autumn

Risk Factors for three-day sickness

·       High vector density

·       Introduction of susceptible cattle

·       Climatic changes

·       Lack of vaccination

- Pathogenesis

After inoculation through insect bites:

Virus enters bloodstream, viremia develops then virus localizes in muscles, joints, and lymphoid tissues. Inflammatory mediators are released, fever and muscle inflammation develop. Hypocalcemia may occur in severe cases.

The disease causes: myositis – polyarthritis - pulmonary edema in severe cases and immunosuppression

Pathogenesis of three-day sickness

- Clinical Signs

Incubation Period

Usually 2–4 days.

Peracute Signs

Sudden onset of fever (40–41.5°C)

Severe depression

Anorexia

Sudden drop in milk production

Acute Signs

General Signs

Stiffness, reluctance to move, muscle tremors, shifting lameness, arched back and recumbency

Respiratory Signs

Nasal discharge, Salivation, Tachypnea, Dyspnea

Musculoskeletal Signs

Swollen joints, Muscle pain, Difficulty rising, Paralysis in severe cases

Gastrointestinal Signs

Ruminal stasis, Constipation followed by diarrhea

Reproductive Effects

Temporary infertility, Occasional abortion

Recovery Phase

Most animals recover withi 1–3 days. Some animals may require several weeks for complete recovery.

- Clinical Forms

Mild Form

Transient fever- Mild stiffness- Quick recovery

Severe Form

Recumbency - Respiratory distress- Pulmonary emphysema -Secondary complications

Fatal Form

Rare but may occur due to respiratory failure, Secondary pneumonia

- Gross Lesions

Postmortem findings may include:

·       Congestion of muscles

·       Serofibrinous fluid in joints

·       Pulmonary edema

·       Emphysema

·       Enlarged lymph nodes

·       Congestion of internal organs

In many cases lesions are mild or absent.

- Histopathological Lesions

Microscopic lesions include:

·       Degeneration of skeletal muscles

·       Muscle fiber necrosis

·       Edema

·       Mononuclear cell infiltration

·       Synovitis

·       Pulmonary congestion

- Diagnosis

Tentative Diagnosis is based on:

Sudden fever, Lameness, Rapid recovery, Seasonal occurrence, Herd outbreaks

- Laboratory Diagnosis

Samples

·       Blood during febrile stage

·       Serum samples

·       Tissue samples

Diagnostic Tests

1. RT-PCR

Most sensitive method for viral detection.

2. Virus Isolation

Performed in Cell culture - Suckling mice

3. Serological Tests

·       ELISA

·       Virus neutralization test

·       Complement fixation test

4. Hematology: may show:

·       Leukopenia

·       Neutrophilia

·       Hypocalcemia

- Differential Diagnosis

- Treatment

There is no specific treatment.

Symptomatic and Supportive Therapy

1. Anti-inflammatory Drugs

·       Flunixin meglumine, Ketoprofen, Meloxicam

to alleviate fever, pain and Inflammation

2. Calcium Therapy

Intravenous calcium borogluconate is beneficial in recumbent animals.

3. Fluid Therapy

Used in dehydrated animals.

4. Antibiotics

Used to prevent secondary bacterial infections.

5. Nursing Care

·       Soft bedding

·       Frequent turning of recumbent animals

·       Easy access to feed and water

- Prevention and Control

Vector Control

·       Insecticides

·       Elimination of standing water

·       Mosquito control programs

·       Housing animals during peak vector activity

Vaccination

vaccination is considered the best preventive measure in endemic regions. different types of vaccines can be used including live attenuated vaccines- inactivated vaccines

Biosecurity Measures

·       Restrict animal movement during outbreaks

·       Quarantine new animals

·       Surveillance programs

- Prognosis

Favorable Prognosis

Most animals recover completely within a few days.

Poor Prognosis usually associated with:

·       Prolonged recumbency

·       Respiratory complications

·       Secondary infections

- References

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