Bartonellosis is a group of infectious diseases caused by bacteria from the Bartonella family. These tiny bacteria can spread from animals to humans through insect bites, scratches, or bites, and can cause a wide range of symptoms—from mild swelling of the lymph nodes to serious complications affecting the heart, brain, and other organs.

Understanding the Outlook: What to Expect When Living with Bartonellosis

The prognosis for bartonellosis varies significantly depending on which type of Bartonella bacteria you have been infected with, how quickly the infection is identified, and whether your immune system is working properly. For many people, the outlook is quite positive, especially when the infection is caught early and treated appropriately.^[5]

If you have been diagnosed with cat scratch disease, which is the most common form of bartonellosis in the United States, your prognosis is generally very good. Most healthy individuals recover completely within two to four months, even without treatment. The swollen lymph nodes that characterize this infection typically resolve on their own, though they may remain tender and enlarged for several weeks or even months. Children and adults with normal immune systems usually experience a full recovery without any lasting effects.^[4][14]

However, the picture can be more complex for people whose immune systems are compromised. If you are living with HIV/AIDS, undergoing cancer treatment, or have received an organ transplant, bartonellosis can become a more serious concern. In these situations, the infection may spread throughout your body, affecting multiple organ systems and requiring longer, more intensive treatment.^[3][5]

Trench fever, caused by Bartonella quintana, generally has a favorable prognosis in otherwise healthy people. The recurring fevers that give this disease its name—episodes that last four to five days and may repeat three to five times—eventually resolve, though the illness can be uncomfortable and disruptive while it lasts. Most people recover fully, although some may experience prolonged fatigue during the recovery period.^[6]

The most serious form of bartonellosis is Carrión’s disease, caused by Bartonella bacilliformis. This infection occurs only in specific regions of the Andes mountains, primarily in Peru. During the acute phase, known as Oroya fever, the mortality rate can reach up to 90% if left untreated. This sobering statistic reflects how the bacteria destroy red blood cells, leading to severe anemia and overwhelming secondary infections. However, when promptly diagnosed and treated with appropriate antibiotics, the survival rate improves dramatically. The chronic phase, which causes skin nodules called verruga peruana, is much less dangerous, though the lesions can be disfiguring and may persist for months or years.^[2][9]

For most people with uncomplicated cat scratch disease, the prognosis includes complete resolution of symptoms without any lasting health problems. Statistical data shows that the global incidence is around 6.4 cases per 100,000 adults and 9.4 cases per 100,000 children aged five to nine years, with most cases resolving favorably.^[2]

It’s important to understand that while bartonellosis can cause severe illness in some cases, modern antibiotics are generally effective at treating the infection when used appropriately. The key to a good outcome is recognizing the symptoms early, seeking medical care, and following through with the complete course of treatment prescribed by your healthcare provider.

How Bartonellosis Progresses Without Treatment

Understanding what happens when bartonellosis is left untreated helps underscore the importance of seeking medical care when symptoms appear. The natural course of the disease varies significantly depending on which Bartonella species is causing your infection and the state of your immune system.^[9]

In the case of cat scratch disease, if you choose not to seek treatment or the infection goes unrecognized, your body will typically mount its own defense. You’ll first notice a small red bump or pustule at the site where you were scratched or bitten, usually appearing within a week of the injury. This bump may fill with fluid and eventually dry up and heal, leaving a small scar. Over the following one to three weeks, the lymph nodes nearest to the scratch site—in your armpit, neck, or groin—will begin to swell. These nodes can become quite large, sometimes reaching the size of a golf ball, and they may be tender to the touch.^[4][5]

For most healthy individuals, these swollen nodes will persist for two to three months, occasionally even longer, before gradually shrinking back to their normal size. During this time, you may experience low-grade fever, general fatigue, and body aches, though some people remain relatively symptom-free aside from the lymph node swelling. The bacteria grow slowly inside your cells, particularly in the cells lining your blood vessels, and this slow growth pattern means your immune system may take quite some time to clear the infection completely.^[3]

However, in approximately 10% of cases, untreated cat scratch disease can spread beyond the local lymph nodes to affect other parts of your body. The infection may travel to your eyes, causing inflammation and vision problems. It may reach your liver and spleen, causing these organs to swell and become tender. In rare cases, the bacteria can invade your bones, leading to painful bone infections, or spread to your central nervous system, causing brain inflammation, seizures, or changes in mental status.^[3][5]

If you have a weakened immune system and develop cat scratch disease without treatment, the progression can be much more severe. The bacteria may cause bacillary angiomatosis, a condition where abnormal blood vessel growth creates tumor-like masses on your skin, in your organs, and even in your bones. These lesions appear as raised, reddish-purple bumps that bleed easily. The bacteria may also cause bacillary peliosis, where blood-filled cysts form in your liver. Without treatment, these conditions can be life-threatening.^[5][9]

Trench fever, when left untreated, follows a distinctive pattern. After an incubation period of about 15 to 25 days following exposure to infected body lice, you’ll experience sudden onset of fever and chills. These febrile episodes last about four to five days each, then resolve, only to return again. This cycle may repeat three to five times over several weeks. Between episodes, you may feel relatively normal, though bone pain—particularly in your shins, back, and neck—often persists. Eventually, in people with healthy immune systems, the fever episodes cease and the infection resolves on its own, though fatigue may linger for weeks or months afterward.^[6]

The most dangerous natural progression occurs with Carrión’s disease. If Bartonella bacilliformis infection goes untreated during the acute Oroya fever phase, the bacteria invade and destroy your red blood cells at an alarming rate. This leads to severe, life-threatening anemia, where your blood can no longer carry adequate oxygen to your tissues. Your immune system becomes temporarily suppressed, leaving you vulnerable to overwhelming secondary infections, particularly from bacteria like Salmonella. Approximately 40% to 90% of people with untreated Oroya fever will die from the combination of severe anemia and secondary infections.^[2][9]

Those who survive the acute phase of Carrión’s disease without treatment often develop the chronic phase weeks or months later. This phase, called verruga peruana, causes red-purple nodules to erupt across your skin. These nodules can range in size from tiny bumps to large masses, and while they are not usually life-threatening, they can be disfiguring and may bleed easily. Without treatment, these skin lesions can persist for months or even years before eventually fading.^[9]

Potential Complications That May Arise

While many cases of bartonellosis resolve without major problems, there are several complications that can develop, some of which can be quite serious. Understanding these potential complications helps you recognize warning signs that should prompt immediate medical attention.^[5]

One of the most concerning complications across all forms of bartonellosis is endocarditis, which is inflammation and infection of the heart valves. This occurs when Bartonella bacteria travel through your bloodstream and attach to the valves that control blood flow through your heart. Over time, the bacteria multiply and form vegetations—clumps of bacteria, blood cells, and other material—on the valve surface. These vegetations can damage the valve, preventing it from closing properly and forcing your heart to work harder to pump blood. You might experience fatigue, shortness of breath, persistent fever, and night sweats. Endocarditis is the most common complication of bartonellosis and carries significant mortality risk if not treated promptly. Many people with Bartonella endocarditis require surgical replacement of the damaged valve in addition to prolonged antibiotic treatment.^[5][6]

Neurological complications can occur when the infection spreads to your nervous system. Some people develop encephalopathy, which means brain dysfunction that can cause confusion, memory problems, difficulty concentrating, personality changes, and altered consciousness. In more severe cases, you might develop encephalitis, an inflammation of the brain itself, which can cause seizures, severe headaches, and even coma. Other neurological manifestations include inflammation of the spinal cord (myelitis), inflammation of the brain’s protective membranes (meningitis), and inflammation of the nerves supplying your eyes (neuroretinitis), which can threaten your vision.^[3][9]

Eye complications deserve special attention because they can threaten your sight. Neuroretinitis causes inflammation of the optic nerve and retina, leading to blurred vision, blind spots, and eye pain. Another condition called Parinaud’s oculoglandular syndrome can develop when the bacteria enter through your eye, causing conjunctivitis (pink eye) along with swollen lymph nodes in front of your ear. While most eye complications can be treated successfully if caught early, delayed treatment may result in permanent vision impairment.^[5][9]

When Bartonella infection affects your blood, severe anemia can develop, particularly with Bartonella bacilliformis. The bacteria invade your red blood cells and cause them to rupture, dramatically reducing your blood’s oxygen-carrying capacity. You’ll feel profoundly weak and fatigued, appear pale, experience shortness of breath with minimal exertion, and have a rapid heartbeat as your body struggles to deliver adequate oxygen to your tissues. In severe cases, this can lead to heart failure and death if not treated urgently.^[9]

Your liver and spleen may become significantly enlarged in a condition called hepatosplenomegaly. As these organs swell, you might feel fullness or pain in your upper abdomen. The enlarged spleen may rupture if subjected to trauma, which is a medical emergency. Liver inflammation can also affect your ability to process medications and toxins, potentially leading to jaundice (yellowing of your skin and eyes) in severe cases.^[5]

Bone infections, though rare, can occur when the bacteria spread to your skeletal system. This causes deep, aching bone pain that worsens over time and doesn’t respond to typical pain relievers. The infection can damage bone tissue and may require prolonged antibiotic treatment, sometimes combined with surgical intervention.^[3]

In people with compromised immune systems, bacillary angiomatosis represents a severe complication where abnormal blood vessels proliferate uncontrollably. These masses can appear almost anywhere—on your skin, in your internal organs, even in your bones. On the skin, they appear as raised red or purple bumps that bleed easily when touched. Internally, they can cause organ dysfunction, bleeding, and other serious problems. Without treatment, bacillary angiomatosis can be fatal.^[5][9]

Another complication seen in immunocompromised patients is bacillary peliosis, where blood-filled cysts form in your liver (and sometimes your spleen). These cysts can rupture, causing internal bleeding, and the condition can significantly impair liver function, leading to a cascade of metabolic problems throughout your body.^[5]

Fluid accumulation represents another category of complications. You might develop pericardial effusion, where fluid accumulates in the sac surrounding your heart, potentially compressing the heart and interfering with its ability to pump blood. Pulmonary edema, or fluid in the lungs, can cause severe shortness of breath and may require emergency treatment.^[5]

It’s worth noting that many of these complications are preventable with prompt diagnosis and appropriate treatment. However, because bartonellosis can present with vague, nonspecific symptoms that mimic other conditions, it’s sometimes not recognized until complications have already developed. This underscores the importance of mentioning any cat scratches, insect bites, or potential exposures to your healthcare provider when you develop unexplained fevers, lymph node swelling, or other concerning symptoms.

Impact on Daily Life: Living with Bartonellosis

A bartonellosis diagnosis can significantly affect your day-to-day activities, relationships, and overall quality of life, though the extent of this impact varies greatly depending on the type and severity of your infection, how quickly you receive treatment, and whether complications develop.^[3]

Physically, even uncomplicated cat scratch disease can make you feel quite unwell for an extended period. The combination of swollen, tender lymph nodes, low-grade fever, fatigue, and body aches can leave you feeling drained and uncomfortable for weeks or months. If the affected lymph nodes are in your armpit, you might find it painful to move your arm normally, making tasks like getting dressed, cooking, or carrying groceries more difficult. When lymph nodes in your neck are affected, turning your head or looking over your shoulder might cause discomfort, which can be particularly problematic if you drive regularly or work at a computer.^[4]

The fatigue associated with bartonellosis deserves special mention because it can be profound and persistent. This isn’t the typical tiredness that improves after a good night’s sleep—it’s a deep, bone-weary exhaustion that makes even simple activities feel overwhelming. You might find yourself needing to rest after taking a shower or making a meal. This level of fatigue can force you to take time off work or school, reduce your working hours, or make adjustments to your daily routine. Parents with young children may find it especially challenging, as they struggle to maintain their usual caregiving activities while dealing with their own illness.^[6]

Work and school attendance often suffer during active infection. The recurring fevers of trench fever, which can last for days at a time, make it nearly impossible to maintain regular attendance or productivity. Even with cat scratch disease, the combination of fever, pain, and fatigue may require extended time away from your usual responsibilities. This can create financial stress, particularly if you don’t have adequate sick leave or disability coverage. Students may fall behind in their coursework, miss important exams, or struggle to catch up once they begin feeling better.^[6]

When neurological complications develop, the impact on daily functioning can be even more severe. Brain fog, memory problems, and difficulty concentrating can make it hard to follow conversations, complete work tasks, or manage household responsibilities. Some people experience personality changes, increased irritability, anxiety, or depression. These neuropsychiatric symptoms can strain relationships with family members and friends who may not understand why you seem different or why you can’t “just snap out of it.” The invisible nature of these symptoms can lead to feelings of isolation, especially if others minimize what you’re experiencing.^[3]

Social activities and hobbies often take a backseat during illness. The fatigue and discomfort make it difficult to participate in activities you previously enjoyed. If you’re an athlete or regularly exercise, you’ll likely need to significantly reduce or stop physical activity during active infection, which can be frustrating and demoralizing. Social gatherings may feel overwhelming when you’re dealing with fever, pain, or exhaustion. Some people withdraw socially during illness, which can contribute to feelings of loneliness and depression.

For people who develop serious complications like endocarditis, the impact on daily life becomes even more significant. You may require hospitalization for weeks, followed by months of recovery. Even after returning home, you might need extended bed rest, have activity restrictions, and require help with basic daily tasks like bathing, dressing, and meal preparation. If surgical valve replacement becomes necessary, the recovery process is lengthy and demands substantial lifestyle adjustments.^[5]

The emotional and psychological toll of bartonellosis shouldn’t be underestimated. Dealing with a diagnosis that many people haven’t heard of, experiencing symptoms that come and go unpredictably, and facing potential complications can provoke significant anxiety. You might worry about whether your symptoms will ever fully resolve, whether you’ll develop complications, or whether the infection will have long-term effects on your health. Some people experience depression, particularly during prolonged illness or when symptoms significantly limit their functioning.

There are strategies that can help you cope with these limitations and maintain quality of life during your illness. Pacing yourself—alternating periods of activity with adequate rest—can help you conserve energy and avoid completely depleting your reserves. Breaking large tasks into smaller, manageable steps makes them less overwhelming. Asking for and accepting help from family, friends, or community resources can ease the burden of daily responsibilities. Some people find that keeping a symptom diary helps them identify patterns, track improvement, and provide useful information to their healthcare providers.

Maintaining open communication with your employer or school about your health limitations can help you negotiate necessary accommodations, such as flexible work hours, the option to work from home, or extensions on deadlines. Under certain circumstances, you may qualify for temporary disability benefits or medical leave protections.

Staying connected with supportive friends and family members, even if social interactions need to be modified to accommodate your energy levels, can help combat feelings of isolation. Some people find it helpful to connect with others who have experienced similar infections, whether through online support groups or patient advocacy organizations.

For most people with uncomplicated cat scratch disease, these impacts are temporary, and normal functioning returns once the infection resolves. However, those with more severe infections or complications may face a longer recovery period and potentially lasting effects on their health and functioning. Being patient with yourself, celebrating small improvements, and working closely with your healthcare team can help you navigate this challenging time.

Supporting Your Loved One: A Guide for Family Members

When someone in your family is diagnosed with bartonellosis, you naturally want to help, but you might not know where to start. Understanding what your loved one is going through and how you can best support them—particularly when it comes to navigating healthcare and potential clinical trial participation—can make a significant difference in their experience and recovery.^[3]

First, it’s important to recognize that bartonellosis, while treatable, can be a frustrating illness for patients. The symptoms may be vague and nonspecific, making diagnosis challenging. Your family member may have seen multiple doctors before receiving a correct diagnosis, and they may have experienced being told their symptoms were psychosomatic or not serious. Acknowledging their experience and validating their symptoms can provide important emotional support.

Learning about bartonellosis yourself helps you understand what your loved one is experiencing. When you educate yourself about how the bacteria spread, what symptoms are typical, and what complications might arise, you can better anticipate their needs and recognize warning signs that should prompt medical attention. You’ll also be better equipped to help them explain their condition to others who may be unfamiliar with this infection.

Practical support often matters most during illness. Your family member may need help with everyday tasks that have become difficult due to fatigue, pain, or other symptoms. Offering to assist with grocery shopping, meal preparation, housework, childcare, or pet care can significantly reduce their stress and allow them to conserve energy for healing. Transportation to medical appointments may be needed, especially if they’re feeling particularly unwell or medications make them drowsy.

When it comes to medical care and the possibility of clinical trial participation, family members can play a crucial advocacy role. Clinical trials are research studies that test new treatments or investigate aspects of diseases that aren’t yet fully understood. For bartonellosis, clinical trials might explore new antibiotics, test different treatment durations, investigate diagnostic methods, or examine long-term outcomes of the infection.

If your loved one is interested in participating in a clinical trial, you can help them search for relevant studies. Websites like ClinicalTrials.gov maintain databases of ongoing clinical trials, searchable by disease name, location, and other criteria. Together, you can review eligibility criteria for different studies to see which ones might be appropriate. Some trials may be looking for people with specific types of bartonellosis, particular severity of symptoms, or certain demographic characteristics.

Understanding the basics of clinical trials helps you support informed decision-making. Clinical trials typically progress through different phases, each with specific goals. Some trials compare new treatments to standard treatments, while others may investigate whether currently used medications are actually effective for bartonellosis. Participation in clinical trials is always voluntary, and participants can withdraw at any time for any reason. All clinical trials must be reviewed and approved by ethics committees to ensure participant safety.

There are important questions you can help your loved one consider and ask when evaluating clinical trial participation. What is the purpose of the trial? What treatments or procedures are involved? Are there potential risks or side effects? Will they receive the experimental treatment or might they receive a placebo? How long does the trial last? Will participation require extra clinic visits, tests, or other time commitments? Will trial participation interfere with other treatments they’re receiving? Are there costs associated with participation, or are treatments and tests provided free of charge?

You can help your family member prepare for conversations with the research team by writing down questions ahead of time, taking notes during discussions, and helping them remember important information shared. Sometimes when people are feeling unwell or anxious, they have difficulty processing and retaining information. Having a support person present who can listen carefully and ask clarifying questions can be invaluable.

If your loved one decides to participate in a trial, you can help them keep track of appointments, medication schedules, and symptom diaries. Many trials require participants to report symptoms regularly or complete questionnaires about their health and functioning. Helping with these tasks ensures accurate record-keeping without adding to their burden.

It’s also important to maintain realistic expectations about clinical trials. Participation doesn’t guarantee improvement and may involve some inconvenience or discomfort. However, trial participation contributes to medical knowledge and may help future patients with bartonellosis, even if it doesn’t directly benefit your loved one. This altruistic aspect provides meaning for many participants.

Emotional support remains crucial throughout the illness and any trial participation. Listening without judgment when your family member wants to talk about their fears, frustrations, or symptoms helps them process their experience. Avoiding statements like “you look fine” or “it could be worse” is important—even well-meaning comments can feel dismissive. Instead, ask what they need, respect their limitations, and celebrate improvements, however small.

If your loved one develops complications or requires hospitalization, your role as an advocate becomes even more important. You can help ensure the medical team is aware of all relevant information about their condition, ask questions when something is unclear, help them understand treatment options, and support their decision-making. Being present during doctor visits, if your family member wants you there, provides both practical and emotional support.

Finally, don’t forget to take care of yourself. Caring for someone with an illness, especially one that persists for weeks or months, can be emotionally and physically draining. Making sure you get adequate rest, maintain your own health, and seek support when you need it ensures you can continue supporting your loved one effectively.