What is the Bartonella bovis pathogen?

The Bartonella bovis pathogen, formerly also known as Bartonella weissi, is a pathogenic bacterium. For the first time, the bacterium was isolated from European ruminants (specifically cattle). Infections caused in cattle are usually asymptomatic, but cause endocarditis and bacteraemia. Like other Bartonella species, B. bovis is gram-negative and rod-shaped. In addition, the bacterium is aerobic, oxidase-negative and relatively small. The Bartonella bovis pathogen comes from the Bartonella family and mainly affects cattle, but has now also been detected in a large number of wild and domestic mammals.

How is Bartonella bovis transmitted?

In a study stated that several factors are responsible for the transmission of Bartonella bovis pathogens. According to this, the distribution as well as the frequency of certain arthropods and environmental factors, i.e. the landscape and georgraphic features, could have some influence on the spread of Bartonella bovis bacteria. Ticks, but also flies were described as possible vectors in the study . But also scratches or bites from infected dogs or cats can lead to disease transmission .

After infection, the Bartonella bovis pathogens colonise the endothelial cells. These are the innermost layer of the blood vessels. Some of the Bartonella bovis pathogens are released into the bloodstream, where they infect the red blood cells (erythrocytes). After an initial division within the erythrocytes, they multiply there until they reach a critical population density.

Where do Bartonella bovis pathogens occur particularly frequently?

The first Bartonella bovis pathogens in cattle were isolated in French Guiana, South America. However, Bartonelle bovis pathogens are also found in other countries, such as France, the USA and the Ivory Coast in West Africa. However, it is highly probable that the pathogens are distributed worldwide. The Bartonella bovis pathogen has now also been detected in cats.

How could the Bartonella bovis pathogen be isolated from cattle?

The isolation of the Bartonella bovis pathogen was sought from the PCR-positive blood samples. Of a total of 224 PCR-positive bovine blood samples , this was successful with one exception. Based on the sequence analyses of gltA, ITS, rpoB genes, ERIC-PCR and an established multilocus sequence typing method (MLST), the molecular heterogeneity of the isolates was investigated. On the same occasion, also investigated the carrier rate of Bartonella bovis pathogens in ticks.

To detect the Bartonella bovis pathogen, one usually resorts to molecular diagnostic tests, such as the PCR test. The molecular diagnosis of extracted whole blood is also possible.

Results from the study analysis of the Bartonella bovis pathogen

Of a total of 224 bovine blood samples, the Bartonella bovis pathogen could be detected in ten cases (4.5 percent). Of these, three beef cattle (1.3 percent) and seven dairy cattle (3.1 percent) were infected . The predominant tick species that could be identified as vectors were Haemaphysalis bispinosa and Rhipicephalus (Boophilus) microplus. Using the MLST method, the genetic heterogeneity of the isolates could be confirmed.

Since the Bartonella bovis pathogen has been detected in cattle for some time , it is assumed that the bacteria have evolved over time to cause minimal harm to their host. In this way, both can live together in a relatively peaceful coexistence . The Bartonella bovis pathogen is very different this survival strategy from other bacteria that can quickly cause fatal diseases. For example, the transmission of anthrax depends on the rapid death of the infected animal so that it can release as many spores as possible into the environment.

What diseases can a Bartonella bovis infection in animals lead to?

A Bartonella bovis infection can lead to endocarditis or bacteraemia. Endocarditis describes an infection of the inner lining of the heart, which particularly affects the heart valves. In the case of bacteraemia, on the other hand, bacteria are present in the bloodstream which lead to an infection. In particular, endocraditis occurs frequently in cattle, but can only be attributed without doubt to a Bartonella bovis infection in a few cases . For veterinarians, the diagnosis of endocraditis in cattle is often a challenge, as the disease can be present with or without external symptoms. Although Trueperella pyogenes, also known as Arcanobacterium pyogenes, Enterobacteriaceae and Streptococcus species are the most common pathogens of endocarditis that can be isolated from the bloodstream of cattle or from a endocraditis valve, other organisms may also be involved in some cases of disease. This is why endocarditis is usually only diagnosed at slaughter, or autopsy .

If a Bartonella bovis infection is present in the cat , the bacterium can be a potential danger to humans and cause a zoonosis. This is an infectious disease that in this case comes from the bacterium Bartonella bovis and causes disease.

A Bartonella infection in humans can lead to the following clinical pictures:

• Endocarditis: infection of the inner lining of the heart, mainly affecting the heart valves,
• Fever,
• Swelling of the lymph nodes (lymphadenopathy),
• Peliosis hepatis: Disease of the liver, which is noticeable by blood-filled cysts.

How is a Bartonella bovis infection treated?

A Bartonella bovis infection in animals can be treated with antibiotics . The following preparations have proven to be effective:

• Doxycycline,
• Gyrase inhibitors,
• Macrolide antibiotics

 
However, despite the use of these preparations, the pathogens cannot be completely eliminated in every affected animal. Furthermore, reinfections are possible at a later time.