Cat Scratch Disease in Veterinary Personnel: New Study Reveals Surprisingly High Exposure Rates
New research examining 300 veterinary professionals and 126 cats shows 64.6% seropositivity—raising important questions about occupational health and zoonotic disease prevention
If you work with cats regularly, you've probably been scratched or bitten more times than you can count. Most of us shrug it off as an occupational hazard, clean the wound, maybe apply some antibiotic ointment, and move on. But a compelling new study published in Transboundary and Emerging Diseases suggests we might need to take Bartonella henselaeexposure more seriously than we do.
Led by Keon Kim and colleagues from universities across South Korea, this research examined both veterinary personnel and their companion cats, using serological and molecular methods to assess infection rates. The findings are striking: nearly two-thirds of veterinary professionals showed serological evidence of B. henselae exposure, highlighting the occupational risk that comes with our careers.
What Is Bartonella henselae and Why Should We Care?
Bartonella henselae is a fastidious, gram-negative bacterium transmitted primarily through cat scratches, bites, or potentially through flea feces contaminating wounds or mucous membranes. It's the causative agent of cat scratch disease (CSD)—a condition most of us learned about in vet school but may not think about much in daily practice.
Classic CSD presents with:
Regional lymphadenopathy (swollen lymph nodes near the scratch/bite site)
Low-grade fever
Malaise and fatigue
Occasionally more serious complications in immunocompromised individuals
Most cases in immunocompetent people are self-limiting, resolving within weeks to months without treatment. But B. henselae can cause more serious disease, including:
Bacillary angiomatosis (vascular proliferative lesions)
Peliosis hepatis (blood-filled cavities in the liver)
Endocarditis (potentially life-threatening)
Neuroretinitis (vision-threatening eye infection)
Encephalopathy (brain involvement)
These severe manifestations are more common in immunocompromised individuals, but they can occur in otherwise healthy people. As veterinary professionals handling cats daily—many of them stressed, fractious, or feral—our exposure risk is substantially higher than the general population.
The Study Design: Comprehensive Sampling
The researchers recruited 300 veterinary professionals and 126 companion cats owned by those professionals across South Korea. This paired sampling approach is particularly valuable because it allows assessment of transmission risk within the veterinary community and their own households.
From humans, they collected:
Blood samples (for serology and PCR)
Saliva samples (for PCR)
Epidemiological questionnaire data about CSD risk factors
From cats, they collected:
Blood samples (for serology and PCR)
Saliva samples (for PCR)
Claw samples (for PCR—looking for Bartonella in the scratch weapon itself)
Fecal samples (for PCR—assessing shedding and environmental contamination)
This comprehensive sampling strategy allowed them to assess not just current infection but also historical exposure (through serology) and to identify potential transmission routes.
The Human Findings: High Seroprevalence
The results from veterinary personnel were striking:
Serological findings (IgG antibodies indicating past or current exposure):
64.6% seropositive (190/294 participants)
Nearly two-thirds of veterinary professionals showed evidence of B. henselae exposure. This is remarkably high compared to general population studies, which typically show seroprevalence of 5-15% in most countries.
Molecular findings (active infection detected by PCR):
Blood: 3% positive (9/298)
Saliva: 1.7% positive (5/298)
The molecular prevalence is much lower than seroprevalence, which makes biological sense. Serology reflects cumulative lifetime exposure—every past infection leaves antibodies that persist for years. PCR detects active, current infection or recent exposure. The fact that 3% of participants had detectable Bartonella DNA in their blood suggests ongoing or very recent infection.
Having Bartonella DNA in saliva is particularly interesting. It suggests potential for:
Oral mucosa colonization
Possible person-to-person transmission (though this is controversial and not well-established)
Indicator of recent bacteremia with salivary shedding
The Feline Findings: Lower Than Expected?
Interestingly, the cats showed much lower infection rates than might be expected:
Serological findings:
5.5% seropositive (6/108 cats)
This is surprisingly low for a cat population. Studies from other countries often show 20-40% or higher seroprevalence in cat populations, particularly outdoor cats or those from shelters.
Molecular findings:
Blood: 10.1% positive (12/119)
Saliva: 0% positive (0/123)
Claws: 1.7% positive (2/119)
Feces: 4.5% positive (5/112)
The higher molecular prevalence compared to seroprevalence in cats (10.1% vs. 5.5%) is somewhat unusual. This might reflect:
Acute infections that haven't yet generated detectable antibodies
Immunological peculiarities in the cat population studied
Potential issues with serological test sensitivity or cutoffs
The fact that these are primarily indoor companion cats of veterinary professionals who likely practice good preventive care
The detection of Bartonella DNA on claws (1.7%) is clinically significant—this confirms that the scratching mechanism can indeed harbor the organism. Even more interesting, fecal shedding (4.5%) suggests environmental contamination is possible, which has implications for indirect transmission.
The Discrepancy: Why Are Vets So Much More Seropositive Than Their Cats?
This is perhaps the most intriguing finding. Veterinary professionals showed 64.6% seropositivity while their own companion cats showed only 5.5%. Several explanations are possible:
1. Occupational Exposure Beyond Personal Pets
Veterinary professionals don't just interact with their own cats—they handle dozens or hundreds of cats annually through their work. Each patient encounter is a potential exposure. Shelter cats, feral cats, and ill cats (who may be more likely to carry Bartonella) represent higher-risk populations than the well-cared-for companion cats in this study.
2. The Companion Cat Selection Bias
Veterinary professionals likely provide excellent preventive care for their own cats, including rigorous flea control. Since fleas are the primary vector maintaining Bartonella infection in cat populations, good flea prevention might explain the lower infection rate in these cats compared to general cat populations.
3. Cumulative Lifetime Exposure
Human seropositivity represents cumulative exposure over an entire career. A veterinary professional working with cats for 10-20 years has had thousands of potential exposure events. Their current companion cats represent only a snapshot of current infection status—these specific cats might not be infected even if previous cats were.
4. Cross-Reactivity or Prior Non-Cat Exposures
While B. henselae is the most common Bartonella species causing human infection, other Bartonella species exist and can cause serological cross-reactivity. Some veterinary professionals might have been exposed to other Bartonella species through different routes (though cats remain the primary reservoir for most human-pathogenic species).
Phylogenetic Analysis: Confirming the Culprit
All PCR-positive samples underwent phylogenetic analysis to confirm species identification. The researchers confirmed that all positive samples were B. henselae, not other Bartonella species.
This is important because:
It confirms cats as the source (rather than other animal exposures)
It validates the diagnostic methods used
It provides strain data that could be used for transmission studies in the future
Risk Factor Analysis: What Increases Exposure?
While the abstract doesn't provide detailed risk factor results, the study included a questionnaire-based epidemiological analysis. Based on known Bartonella epidemiology and similar studies, likely risk factors for veterinary personnel include:
Professional factors:
Years in practice (longer exposure time)
Type of practice (shelter medicine, feral cat work higher risk)
Use of personal protective equipment
Wound care practices after scratches/bites
Number of cats handled weekly
Personal factors:
Cat ownership (though this study suggests work exposure may exceed home exposure)
Number of cats owned
Flea control practices on personal pets
Indoor vs. outdoor cat lifestyle
Clinical Implications: Should We Be Worried?
The 64.6% seropositivity rate might sound alarming, but context matters:
For Most of Us: Probably Not a Major Concern
Most B. henselae infections in immunocompetent individuals are asymptomatic or cause mild, self-limiting disease
Many veterinary professionals in this study were seropositive but presumably healthy and asymptomatic
The body's immune system typically clears the infection without treatment
Long-term consequences in healthy individuals are rare
But Awareness Is Important:
We should recognize Bartonella as a legitimate occupational hazard and take reasonable precautions, especially for:
Immunocompromised colleagues:
HIV/AIDS patients
Those on immunosuppressive medications
Post-transplant patients
Chemotherapy patients
Pregnant veterinary personnel (risk of vertical transmission is debated)
Anyone developing post-scratch symptoms:
Persistent lymphadenopathy (swollen lymph nodes)
Prolonged fever without obvious cause
Unusual skin lesions
Neurological symptoms
Vision changes
Practical Prevention Strategies
Based on this study's findings, here are evidence-based recommendations:
For Veterinary Professionals:
Handle cats with appropriate restraint and protective equipment
Use gloves when handling fractious cats
Employ proper restraint techniques to minimize scratch/bite risk
Consider bite-proof gloves for high-risk situations (feral cats, aggressive patients)
Practice immediate wound care
Thoroughly wash scratches and bites with soap and water immediately
Don't ignore "minor" scratches—they're the primary transmission route
Consider prophylactic antibiotics for deep puncture wounds (though evidence for routine prophylaxis is limited)
Recognize symptoms early
Be aware of CSD clinical signs
Seek medical attention for persistent lymphadenopathy after cat scratches
Inform human healthcare providers about occupational cat exposure
Consider screening if immunocompromised
Serological testing might be appropriate for immunocompromised veterinary personnel
Prophylactic antibiotics may be considered in high-risk situations
For Cat Owners (Including Ourselves):
Rigorous flea control
Fleas are the primary vector maintaining Bartonella in cat populations
Year-round flea prevention dramatically reduces infection risk
Indoor-only lifestyle reduces flea exposure
Nail trimming
Keeping cats' nails trimmed reduces the depth and severity of scratches
The study found Bartonella DNA on 1.7% of claws—reducing scratch trauma helps
Supervise children
Children are at higher risk for CSD (rough play = more scratches)
Teach appropriate cat handling
Seek medical attention for infected-looking scratches
Test shelter/rescue cats?
While routine screening isn't typically recommended, high-risk populations (shelters, catteries) might benefit
Treatment of asymptomatic cats is controversial and not usually recommended
Treatment Considerations
For humans with CSD:
Most immunocompetent patients: supportive care, monitor for resolution (typically 2-4 months)
Severe cases or immunocompromised: azithromycin is first-line (500 mg day 1, then 250 mg daily for 4 days)
Alternative antibiotics: doxycycline, rifampin, or fluoroquinolones for complicated cases
Endocarditis cases require prolonged treatment (weeks to months)
For cats:
Treatment of asymptomatic carrier cats is controversial
No proven protocol reliably clears infection
Azithromycin (10 mg/kg q24h for 7-14 days) sometimes used but efficacy unclear
Focus should be on flea control rather than antibiotic treatment
Geographic Considerations: Why Korea?
This study was conducted in South Korea, and it's worth noting that Bartonella epidemiology varies globally based on:
Cat population density and lifestyle (indoor vs. outdoor)
Flea prevalence and species
Climate factors affecting vector populations
Cultural practices regarding cat ownership and veterinary care
While we can't directly extrapolate these exact prevalence figures to other countries, the principles remain applicable worldwide. Bartonella is a global pathogen, and veterinary professionals everywhere face occupational exposure.
The relatively low cat prevalence in this study (compared to some other countries) might reflect South Korea's growing emphasis on indoor cat ownership and preventive veterinary care—a trend seen in many developed nations.
Research Limitations and Future Directions
A few limitations worth noting:
Selection bias: These are companion cats of veterinary professionals, likely receiving better care than average
Cross-sectional design: Can't determine incidence or temporal relationships
Limited clinical correlation: We don't know how many seropositive people were symptomatic
Questionnaire data not fully reported: Risk factor analysis would strengthen conclusions
Future research should explore:
Longitudinal studies following veterinary students through their careers
Clinical correlations: Do seropositive individuals report more CSD-compatible symptoms?
Intervention studies: Does enhanced flea control reduce human seroprevalence?
Strain typing: Can we trace transmission from specific cats to humans?
Protective equipment efficacy: Do gloves actually reduce transmission?
The Bottom Line
This comprehensive South Korean study reveals that Bartonella henselae exposure is extremely common among veterinary professionals, with nearly two-thirds showing serological evidence of infection. While most infections are asymptomatic or mild, the high prevalence underscores the importance of recognizing Bartonella as a legitimate occupational hazard.
Key takeaways for practice:
Cat scratches aren't trivial—they're potential vectors for a pathogen we're highly exposed to
Flea control is critical—both for our patients and for reducing zoonotic disease risk
Wound care matters—immediate, thorough cleaning of cat scratches and bites
Awareness protects—knowing CSD symptoms helps with early recognition and treatment when needed
Immunocompromised colleagues face higher risk—extra precautions are warranted
We chose careers working with animals, accepting certain occupational hazards as part of the job. Bartonella exposure is one of those hazards. But unlike the emotional toll or physical injuries from
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