Brucellosis & Ephemeral Fever in Cattle: Farmer’s Guide

Bovine Ephemeral Fever in Cattle

Bovine ephemeral fever, also known as "three-day sickness," is a viral disease that affects cattle and, on occasion, buffaloes. This disease is primarily spread through mosquitoes, making it an arthropod-borne virus.

The symptoms of bovine ephemeral fever include a brief fever, shaking, lameness, and muscular stiffness. This mild febrile disease is transmitted by insect vectors and can cause muscle tremors, limb stiffness, lameness, and a decrease in milk supply.

Prevalence of Bovine Ephemeral Fever (BEF) in Cattle

In many parts of Africa and Asia, there is a common occurrence of seasonal diseases that coincide with the prevalence of vectors like Culicoides insects and mosquitoes. The morbidity and mortality rates for these diseases vary between 5% and 10%, and 1% respectively. However, mortality rates are generally not high, except in cases where there is a secondary bacterial infection, which is more likely to occur in animals that are in good condition.

Causes of Bovine Ephemeral Fever (BEF) in Cattle

Bovine ephemeral fever is a disease of cattle and water buffalo caused by a rhabdovirus and transmitted by flying, biting insects. The virus is present in the blood, where it is closely attached to the leucocyte-platelet fraction.

Transmission of Bovine Ephemeral Fever (BEF) in Cattle

The disease is transmitted by biting insects that can fly. Transmission is cyclical in the Culicoides species, as well as other members of the Ceratopogonidae family. The disease spreads through the inoculation of whole blood. Only livestock are susceptible to this disease. It cannot be transmitted through direct contact or contact with discharges.

Clinical Signs of Bovine Ephemeral Fever (BEF) in Cattle

Biphasic or polyphasic fever affects calves the least when they are under 6 months old, and they show no clinical signs. Fat cows and bulls are the most severely affected. The incubation period lasts between 2 and 10 days, followed by a sudden high fever of short duration.

Symptoms of the disease include anorexia, short fever, shivering, lameness, and muscular stiffness. Additionally, there is a marked drop in milk production, salivation, and nasal and ocular discharge. The animal may become recumbent (lateral).

On the third day, eating and rumination begin. However, milk production does not return to normal until the next lactation, and there may be insidious losses, such as reduced muscle activity and infertility.

Postmortem findings in bovine ephemeral fever reveal the only important lesion to be the enlargement and edema of all lymph nodes. Pulmonary lesions may also occur if there is secondary bacterial invasion and petechiation of the serous membrane.

Diagnosis of Bovine Ephemeral Fever

The diagnosis of bovine ephemeral fever involves the identification of mild clinical signs of the disease, the presence of a vector in the blood, blood serum, and lymph tissues, as well as serology testing.

One possible differential diagnosis for bovine ephemeral fever is a parturient paresis response to calcium borogluconate treatment.

Note:

To manage bovine ephemeral fever, you should first control the insect vectors, followed by vaccination. However, the vaccine does not provide lasting immunity.

For symptomatic treatment, phenylbutazone can be used to alleviate residual muscle stiffness, but drenching animals should be avoided because it may affect the muscles involved in swallowing. The most effective treatment is complete rest, and recovering animals should not be subjected to stress. Treatment for recumbent cows involves the administration of NSAIDs along with supportive care.

Brucellosis in Cattle

Brucellosis is a highly contagious disease in cattle caused by the Brucella bacterium. The disease spreads when animals come into contact with female cattle that have aborted fetuses or discharged placental tissues and fluids. This disease is also known as "contagious abortion."

Contagious abortion is a specific disease caused by Brucella abortus. The infection can persist in the genital system of bulls. In females, it is characterized by chronic inflammation of the uterus, particularly the mucous membrane, and usually results in abortion between the 5th and 7th months of pregnancy.

Note:

Individuals can contract the sickness from diseased animals or animal products contaminated with the bacterium. Sheep, cattle, goats, pigs, and dogs are the animals most commonly affected.

Although not all infected cows abort, in over 50% of cases, pregnancy runs to full term. It is important to note that any animal that has aborted once may be almost as dangerous during its subsequent calvings.

Control Policy for Brucellosis in Cattle

This policy is based on the following principles:

1. Quick and accurate identification of diseased animals
2. Identification of high-risk contact animals
3. Isolation from non-infected animals of the same herd
4. Rapid removal and slaughter of infected animals
5. Rapid and accurate tracing of reactors back through contact herds
6. Rapid and accurate tracing of animals that have moved through infected herds
7. Identification of animals and herds at risk and rapid check testing
8. Effective cleansing and disinfection of premises
9. Effective epidemiological investigations
10. Good surveillance systems
11. Good cooperation between farmers
12. Appropriate compensation and incentives to eradicate the disease
13. Effective enforcement procedures
14. Removal of the risk of reintroduction at the herd, regional, and country-wide levels

Transmission of Brucellosis in Cattle

The transmission of brucellosis in cattle occurs when cows lick contaminated materials or the genital area of other cows, or when they ingest feed or water contaminated with the disease-causing organisms. Although there are occasional exceptions, the general rule is that infected or exposed animals carry brucellosis from one herd to another. Additionally, the disease can spread when animals come into contact with infected female cattle, aborted fetuses, or discharged placental tissues and fluids.

Brucellosis can be transmitted through the mouth or vagina during mating. A bull that has served an infected cow may then serve another cow and transmit the disease. When a bull is a carrier, the contamination of litter from a previous case can also be transmitted by the hand and arm of a person handling an aborted fetus, old carrier cows, milk from infected cows, predilection sites, pregnant uterus, udder, joint capsules, tests, and accessory male sex glands, among other possible transmission routes.

Clinical Signs of Brucellosis in Cattle

The appearance of infected animals cannot effectively be used for detection. In pregnant cows or calves, abortions, the birth of weak calves, and vaginal discharge are the most obvious signs. Changes in the normal lactation period due to abortions and delayed conceptions may lead to a reduction in milk production.

Some cattle can become carriers of the disease, shedding the bacteria without exhibiting clinical signs of illness or localized lymph node enlargement. The bacteria may continue to be shed for 10 or more days with a continuous reddish-brown discharge. In bulls, the symptoms are characterized by a very slight absence of orchitis and epididymis.

Abortion without any preliminary symptoms and premature birth of calves can occur. Most cows that abort once will carry the next calf to full term, and only a few will abort three times. If the abortion happens early in pregnancy, the fetal membranes are expelled from the calf. However, if it happens towards the end, there is always a retention of these membranes.

In postmortem examinations of Brucellosis, there are no visible signs; necrotic areas are present in the placenta.

Diagnosis of Brucellosis in Cattle

To perform the agglutination test, follow these steps:

1. Obtain a blood sample from a cow and allow it to coagulate to obtain blood serum.
2. Mix the serum at ratios of 1:10, 1:20, and 1:40 with a suspension of organisms.
3. Incubate the mixture for 24-48 hours.
4. Look for agglutination, which indicates a positive result.

Treatment of Brucellosis in Cattle

There is no curative or preventive treatment available for pregnant cows to avoid discharging after an abortion or the use of pessaries, which may lead to contamination of the area. Antiseptic irrigation of the uterus may also not be effective in preventing discharge. In general, a combination of antibiotics such as doxycycline and rifampin is recommended for a minimum of 6-8 weeks to address this issue.

Prevention of Brucellosis in Cattle

The most effective strategy for preventing infection is to eliminate it in animals. Vaccinating cattle, goats, and sheep is recommended in areas where the disease is prevalent. In areas with low prevalence rates, serological or other testing and culling may also be effective.

Regular vaccination of heifer calves with the S19 vaccine yields the best results. The resulting immunity protects against natural infection and consequent abortion for at least five pregnancies, sometimes the cow's entire milking life.

Adults are not vaccinated due to the potential for false positives in the agglutination test. This test is used to differentiate between the effects of the last vaccine dose and natural infection. False positives can result in the excretion of seemingly virulent strains of Brucella abortus in milk. It's also essential to handle and dispose of aborted fetuses, fetal membranes, and discharges with caution to prevent disease transmission among cattle and human health.

It's advisable to avoid purchasing replacements from non-accredited farms or herds with the disease. Additionally, it's important to note that infected farm dogs can spread the disease.

Conclusion

Bovine ephemeral fever and brucellosis are two significant diseases that affect cattle and have implications for both animal health and farm productivity. Bovine ephemeral fever, also known as "three-day sickness," is primarily transmitted through mosquitoes and causes temporary fever, lameness, and muscular stiffness in cattle. On the other hand, brucellosis is a highly contagious disease caused by the Brucella bacterium, leading to abortion and reproductive issues in cattle.

To effectively manage these diseases, it is crucial to implement control measures and preventive strategies. For bovine ephemeral fever, controlling insect vectors and vaccination play key roles in disease management.

Symptomatic treatment and rest are recommended for affected animals. As for brucellosis, identifying and isolating diseased animals, rapid removal and slaughter of infected animals, and good surveillance systems are crucial in controlling its spread. Vaccination of young animals and careful handling of aborted materials are important preventive measures.

While managing these diseases is essential for maintaining herd health, it's important to prioritize biosecurity and animal welfare. Regular monitoring, proper diagnosis, and adherence to control policies are vital in minimizing the impact of these diseases on cattle populations. By implementing these measures, farmers can work towards healthier herds and a more sustainable future for cattle farming.