The term ‘Bartonellosis’ refers to any infectious disease caused by the bacteria ‘Bartonella’. A range of diseases exist under this umbrella term, and each can result in a variety of symptoms such as headaches, high temperature, a rash, etc. However, it has also been seen to cause cardiac manifestations (heart complications) in some patients. In this article, we explore what Bartonellosis is and how it can affect heart health. 

What is Bartonellosis?

Bartonellosis is an infectious disease that has been produced by bacteria called ‘Bartonella’. There are around 20 species of Bartonella,¹ but the species most commonly associated with infection of humans are: 

• Bartonella henselae
• Bartonella quintana
• Bartonella bacilliformis 

These bacteria can cause multiple diseases in humans, such as: 

• Cat scratch disease: A relatively rare bacterial infection. Cats becomes infected with the bacteria by fleas, which are then passed to humans through a scratch or bite. Symptoms include high temperature, swollen lymph nodes, and rash/bumpy skin
• Trench fever: A disease transmitted between humans by body lice-carrying the bacteria. Common symptoms can include headaches, sore eyes, weakness, pain in joints/muscles and a high temperature
• Carrión disease: An illness transmitted to humans when they are bitten by certain sand flies in the Peruvian Andes and some parts of Ecuador/southern Colombia. It is a biphasic disease meaning it has 2 phases. The 1st (acute) phase is called Oroya fever and is life-threatening, usually affecting children the most. The 2nd (chronic) phase occurs in people who have already been exposed to the bacteria and is not fatal, often leading to ‘Peruvian warts’ on the skin²

Cat scratch disease is caused by Bartonella henselae, trench fever by Bartonella quintana and Carrión disease by Bartonella bacilliformis. Infection caused by these bacteria has been seen worldwide, except, for the Bartonella bacilliformis, which is only seen in some areas of South America.

Can Bartonellosis cause heart complications?

Research has shown that the bacteria Bartonella can be a cause of endocarditis in humans, which in turn can lead to heart failure and a stroke.³

Bartonellosis and endocarditis 

Endocarditis is a rare and potentially life-threatening condition where the heart’s inner lining (the endocardium) becomes infected and inflamed. This usually occurs when bacteria – such as Bartonella – get into the bloodstream and end up in the heart. In infective endocarditis (IE), the heart valves (which help control the direction in which your blood flows) are also infected. 

Infective endocarditis can then result in other heart complications such as: 

• Heart failure: When the heart can no longer pump a sufficient amount of blood around the body
• Stroke: When the brain’s blood supply is stopped

It has been proven that Bartonella bacteria when it infects a person’s blood, can travel to the heart and cause infective endocarditis. This is referred to as ‘Bartonella endocarditis’. One study looked at how many cases of infective endocarditis were Bartonella endocarditis.⁴

Results in certain countries were as follows: 

• 0% in Sweden
• 1.1% in the UK 
• 3% in France & Germany 
• 15.6% in Algeria 
• 9.8% in Tunisia 

Bartonellosis and blood culture negative endocarditis (BCNE)

The most common way to diagnose infective endocarditis (among others) is to perform microbiological testing through blood cultures. This is essentially when experts perform lab tests to check for bacteria in blood samples. 

‘Blood culture-negative endocarditis’ (BCNE) refers to when these blood cultures do not allow for a diagnosis of the bacteria causing the endocarditis. This can apply to between 2.5% and 31% of cases of endocarditis.⁵

One review in France, found that around 20-30% of the cases recorded of BCNE are Bartonella endocarditis – making it the second most common endocarditis cause.⁴

Bartonella endocarditis and pre-existing conditions 

Whilst research on the subject does show that Bartonellosis can be a cause of endocarditis (and therefore potential further complications like heart failure or a stroke), it is important to recognise that this has been found to be more prevalent in certain patients with pre-existing conditions. 

Bartonella endocarditis tends to occur in those with pre-existing abnormalities to their heart valves which can then make them more susceptible to infective endocarditis.⁴ Indeed one study found that the patients suspected of having BCNE caused by Bartonella also had:

• A prosthetic (replacement) heart valve
• Other exposure to potential causes of endocarditis
• Kidney failure with positive PR3-ANCA

Therefore it should be considered that pre-existing conditions may make it more likely that someone can develop endocarditis from Bartonellosis.

Bartonella endocarditis symptoms

Bartonella endocarditis has been seen to cause non-specific (vague) symptoms in patients, including weight loss, fatigue, weakness and a fever.⁶

Bartonella endocarditis treatment

Bartonella endocarditis can seriously damage the heart valves, and as such over 90% of cases require valvular surgery – a higher percentage than for those with endocarditis with other causes.⁴ 

In valvular surgery, the surgeon will try to repair the heart valves. There are various types of surgery and the type chosen will depend on each patient’s condition. 

This is largely the case in general treatment of Bartonella endocarditis. Antibiotics may also be used to treat it, but the treatment plan chosen will depend on the specificities of a patient’s case and history. 

Bartonellosis and atherogenesis 

Atherogenesis

The Oxford definition of atherogenesis is the formation of fatty deposits in the arteries. When the heart’s arteries have these fatty deposits (plaque) inside of them, they become clogged or blocked, in turn restricting the heart’s ability to pump blood around the body and to function properly. 

Endothelial progenitor cells 

Endothelial progenitor cells (EPCs) are cells which have been found to be very important in vascular repair (repairing cells in vessels). 

Bartonellosis and atherogenesis: the link

Recently, it has been proven that Bartonella henselae (which can cause cat scratch disease) can infect EPCs and cause damage to them.

It has been suggested that if the Bartonella bacteria infects and damages these EPCs, their ability to repair vessels (such as arteries) will be impaired. If the EPCs are not able to repair damage to the arteries, then it may be that the growth of fatty deposits in these arteries (atherogenesis) is accelerated.⁷

In this way, Bartonella could be a risk factor for heart disease, however, a lot more research is needed in this area to confirm these hypotheses. 

Bartonellosis and myocarditis

Myocarditis is when the heart muscle (the myocardium) becomes inflamed. This is usually after contracting a virus. It is a known complication of a Bartonella infection in cats. Whilst it is very rare, there have also been reports of myocarditis developing from Bartonellosis in humans too.

In 1997, Homberg et al reported a 60-year-old man from Sweden who died suddenly from Bartonellosis and who had myocarditis.⁸ 

The link between myocarditis and Bartonella henselae was then histologically confirmed through testing in the case of a 32-year-old man reported in 2001, who presented with both conditions.⁹

In another case study, Honegger et al. also presented the case of a 22-year-old man who had myopericarditis – this refers to when someone has myocarditis and pericarditis (inflammation of the pericardium, the sac surrounding the heart). This myopericarditis was in fact associated with bartonellosis (in his case, cat scratch disease).

So, whilst extremely rare, various cases have demonstrated that bartonellosis can cause myocarditis – and perhaps even pericarditis. 

Summary

• Bartonellosis refers to infectious diseases caused by Bartonella bacteria 
• These include cat scratch disease, trench fever and Carión disease
• If Bartonella gets into the bloodstream, it can travel to the heart
• Then it can infect the heart’s inner lining (endocardium) and valves
• This causes infectious endocarditis which can lead to heart failure or stroke
• Bartonella may also damage EPCs which repair damage to vessels in the heart
• Meaning Bartonellosis may increase the risk of heart disease
• There have been a few reports of Bartonella-associated myocarditis too but this appears to be rare