Bartonellosis and the Spleen

The spleen, what is it? The subject of jokes and silly songs, and at the same time unpredictable. It can very rarely rupture without warning and even more rarely without an identifiable cause. Some researchers suggest that the number of times there is not an identifiable cause is probably overstated because the cause is identifiable but missed. Recently, spontaneous splenic rupture has been associated with COVID-19.

Very rarely, a person can be born without a spleen or with a spleen that does not work, and about 10% of people are born with a small extra spleen. The spleen is a specialized lymph node that cleans the blood. As such, it is exposed to almost everything that can go wrong in blood, including abnormal blood cells, cancerous cells, and pathogenic bacteria and viruses.

When someone is born without a spleen or if they must have their spleen removed such as if it is damaged in a trauma, extra care for their health is often warranted. Vaccinations that are not commonly recommended may be added for people without a spleen, and they may need to be more on top of seeking medical treatment and preventive care to protect them from infections.

Infections that reach the liver also often involve the spleen: “hepatosplenic” describes conditions that affect these two organs together. When the spleen is responding to an infection it can become larger, sometimes resulting in tenderness in the upper left quadrant and pain going up into the left shoulder. An enlarged spleen is common in active cases of infectious mononucleosis (mono) or Epstein-Barr virus infection.

Bartonella henselae acute infection is called “cat scratch disease” and is characterized by a fever and swollen lymph nodes close to the scratch. A mouse study using Bartonella birtlesii found that the bacteria count was actually higher in the spleen than in the lymph nodes, likely as a result of the organ’s role in cleaning the intracellular pathogen from the erythrocytes. Mice without spleens had 10 times higher bacteria levels and were sick for two weeks longer. This study suggests that the spleen plays an important role in responding to Bartonella species infection.

In a record review of children with hepatosplenic symptoms, nine of 13 children had evidence of Bartonella henselae infection. Those who had liver biopsies primarily showed necrotizing granuloma. The authors concluded:

“Systemic B. henselae infection represents an important cause of inflammatory hypoechogenic hepatosplenic lesions in children. Serology provides rapid diagnosis, avoiding multiple and invasive investigations. Hepatosplenic involvement can be found even in children with typical cat-scratch disease without apparent systemic manifestations. The frequency of liver and/or splenic involvement in cat-scratch disease is probably underestimated.”

 

While spleen findings in immunocompetent adults are less common, they do occur. Occasionally a case may present with only spleen lesions and not obvious liver involvement. One such case report involved a 54-year-old woman whose only symptoms were fever and left upper quadrant pain. Her two affectionate cats pointed the way to a potential diagnosis and bartonellosis was identified and treated with antibiotics.

Conclusion

Bartonellosis has a wide variety of non-specific, multi-system symptoms that mimic other health conditions. Left upper quadrant pain and fever is commonly associated with viral infections like mono, but it can also be the result of Bartonella species infection. It may also be associated with other conditions such as endocarditis. It is important for healthcare providers to consider Bartonella as a cause of hepatosplenic conditions for patients who have high exposure to animals and insect vectors like fleas and ticks.