Anaplasmosis & Heartwater in Cattle: Signs, Causes & Treatment

Anaplasmosis (Gall Sickness) Disease in Cattle

Anaplasmosis, also known as Gall Sickness, is a tick-borne disease primarily caused by Anaplasma marginale and, to a lesser extent, Anaplasma centrale. It affects cattle and, although sheep and goats can also be infected, cattle are most commonly affected.

The disease is characterized by symptoms such as fever, progressive anemia, and jaundice. Anaplasmosis poses a significant economic burden due to the debilitating effects it has on affected animals. This article provides an overview of anaplasmosis, covering its causes, transmission, clinical signs, diagnosis, treatment, and control measures.

Causes of Anaplasmosis or Gall Sickness Disease in Cattle:

1. Anaplasma marginale (cattle and wild ruminants - most pathogenic)
2. Anaplasma centrale (cattle and wild ruminants - less pathogenic)
3. Anaplasma ovis (sheep and goats) - intra-erythrocytic parasites appearing as spherical bodies

Transmission of Anaplasmosis or Gall Sickness Disease in Cattle:

Anaplasmosis can be transmitted by five different tick species and blood-sucking flies like stable flies and horse flies. The disease can also be mechanically transmitted through the direct inoculation of contaminated needles and surgical or dehorning instruments.

Mechanical transmission by biting flies is also possible. Animals at the peak of infection, with a high number of parasites in their red blood cells, are more likely to transmit the disease. Additionally, a carrier state exists, contributing to outbreaks.

Resistance to anaplasmosis decreases with age, and wild ruminants serve as reservoirs.

Clinical Signs of Anaplasmosis or Gall Sickness Disease in Cattle:

The main clinical signs of anaplasmosis include fluctuating fever exceeding 40 ºC, rumen stasis, constipation, decreased milk production in dairy animals, anemia, and jaundice. These signs typically appear three to four weeks after exposure and are accompanied by fever.

Abortion in pregnant animals is common, and intercurrent infections with other microorganisms can predispose animals to anaplasmosis. Sheep and goats usually experience subclinical symptoms.

Postmortem Findings of Anaplasmosis or Gall Sickness Disease in Cattle:

Postmortem examinations reveal common lesions such as emaciation, dehydration, jaundice, and anemia. The blood appears thin and watery, the liver is enlarged and bronze-colored, the spleen is enlarged and dark, the kidneys are enlarged and soft, and the heart muscles are soft and flabby.

Diagnosis involves identifying Anaplasma organisms through clinical symptoms, autopsy findings, and blood smears. Differential diagnosis includes leptospirosis, babesiosis, anemia, and jaundice.

Treatment of Anaplasmosis or Gall Sickness Disease in Cattle:

Tetracycline or imidocarb injections are administered according to the manufacturer's guidelines. Supportive treatment, such as Vitamin B Co and Rumix, is also recommended. To prevent anaplasmosis infections, it is essential to control ticks and flies by dipping animals.

Broad-spectrum antibiotics like oxytetracycline (3-5 mg/kg) and chlortetracycline (5-10 mg/kg) are effective. Early initiation of therapy with tetracycline, imidocarb (Imizol) at 5 mg/kg, and blood transfusions yields better results. Providing a calm environment, shelter from inclement weather, and ensuring a comfortable atmosphere are also recommended to minimize stress.

Heartwater or Cowdriosis Disease in Cattle

Heartwater, also known as cowdriosis, is a severe tick-borne rickettsial disease caused by Ehrlichia ruminantium and transmitted by Amblyomma ticks. It is a highly fatal and non-contagious disease that primarily affects ruminants.

Susceptible domestic ruminants can experience mortality rates as high as 90%. Heartwater disease is closely associated with the presence or absence of the tick vector, particularly in African regions where its prevalence is relatively high.

Causes of Heartwater or Cowdriosis Disease in Cattle:

Heartwater is caused by the bacterium Ehrlichia ruminantium, which is transmitted by infected ticks. The disease commonly leads to the death of infected animals. Its virulence varies, and mortality rates of up to 90% have been reported.

Cattle, sheep, and goats with temperate climate breeds are more susceptible compared to indigenous breeds that have previous exposure to the microorganism.

Age also influences susceptibility, with animals under three weeks old exhibiting high resistance, while recovered animals develop immunity and do not act as reservoirs of infection.

Transmission of Heartwater or Cowdriosis Disease in Cattle:

Heartwater is transmitted through the bite of infected Amblyomma ticks, commonly known as bont ticks. The transmission occurs during feeding and is a transtadial process. The parasites primarily reside in endothelial cells, particularly within the jugular vein, vena cava, and blood vessels of the brain.

Clinical Signs of Heartwater (Cowdriosis) Disease in Cattle:

Clinical signs of heartwater disease typically manifest after an incubation period of 2-3 weeks. Infected animals may exhibit fever, anorexia, muscular tremors, and nervous signs such as continuous limb movements, convulsions, and neck rigidity.

The disease often progresses to hypersensitivity and ultimately results in death. Calves and lambs up to four weeks old display resistance, while severe diarrhea is a common feature during recovery.

Postmortem Findings of Heartwater (Cowdriosis) Disease in Cattle:

Postmortem examinations reveal the accumulation of fluid in the pericardial sac, pleural, and peritoneal cavities. The spleen appears enlarged and edematous, and small hemorrhages are observed on the endocardium, stomach, and intestinal mucosa, trachea, and lymph nodes of the viscera.

Diagnosis of Heartwater Disease:

Diagnosis of heartwater disease involves essential steps such as identifying the presence of the bont tick, conducting smears from endothelial cells in the jugular vein, and observing postmortem signs such as fluid accumulation in the cavities.

Differential diagnosis includes diseases like tetanus and rabies. Sulfadimidine is commonly used for the treatment of heartwater in cattle.

Control of Heartwater (Cowdriosis) Disease in Cattle:

Effective control of heartwater disease involves tick control measures and addressing trichomoniasis, a venereal disease in cattle that can also impact heartwater transmission.

Vaccination using Oxytetracycline at a dosage of 10 mg/kg/day or Doxycycline at 2 mg/kg/day is recommended. Proper management practices include ceasing breeding for at least three months, using artificial insemination or clean bulls for natural service, and ensuring sterile immunity.

Infected cows should be culled as they may act as carriers. It is essential to expose uninfected bulls only to uninfected females to prevent infection.

Conclusion

In conclusion, anaplasmosis (gallsickness), heartwater (cowdriosis), and bovine trichomoniasis are significant diseases that affect cattle. Anaplasmosis is primarily transmitted by ticks and blood-sucking flies, causing fever, anemia, and jaundice. Heartwater, a tick-borne rickettsial disease, is fatal and characterized by high mortality rates in susceptible ruminants.

Bovine trichomoniasis is a venereal disease caused by the protozoan Tritrichomonas fetus, leading to infertility, abortions, and reduced calf production.

Understanding the causes, transmission methods, clinical signs, postmortem findings, diagnosis, treatment, and control measures of these diseases is crucial for effective management and prevention. Timely intervention, such as administering appropriate antibiotics, implementing tick control measures, and practicing strict biosecurity protocols, plays a vital role in mitigating the impact of these diseases on cattle health and productivity.