What illnesses can be contracted from fleas? - briefly
Fleas transmit several human pathogens, most notably plague (Yersinia pestis), murine typhus (Rickettsia typhi), cat‑scratch disease (Bartonella henselae), and flea‑borne spotted fever (Rickettsia felis).
What illnesses can be contracted from fleas? - in detail
Flea bites can introduce a range of pathogenic organisms into humans. The most significant agents are bacterial, although some parasites have been reported in rare cases.
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Plague (Yersinia pestis) – transmitted when an infected flea feeds on a human, injecting the bacterium from its gut. Symptoms begin with sudden fever, chills, and painful swollen lymph nodes (buboes); pneumonic forms present with cough and hemoptysis. Endemic regions include parts of Africa, Asia, and the western United States. Prompt antibiotic therapy (streptomycin, doxycycline, or gentamicin) reduces mortality dramatically.
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Murine typhus (Rickettsia typhi) – acquired from the feces of infected fleas that contaminate skin lesions or mucous membranes. The disease manifests as fever, headache, rash, and sometimes encephalitis. It is common in coastal regions of the southern United States, Southeast Asia, and the Mediterranean. Doxycycline is the treatment of choice.
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Flea‑borne spotted fever (Rickettsia felis) – caused by a rickettsial organism found in cat and dog fleas. Clinical picture includes fever, myalgia, and a maculopapular rash; severe cases may develop thrombocytopenia or hepatitis. Cases have been reported worldwide, especially in tropical and subtropical zones. Doxycycline remains effective.
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Cat‑scratch disease (Bartonella henselae) – while primarily transmitted by scratches, the bacterium can also be passed through flea feces that contaminate wounds. The infection produces regional lymphadenopathy, low‑grade fever, and, occasionally, hepatic or splenic lesions. It is prevalent wherever domestic cats and their fleas are present. Azithromycin shortens symptom duration; severe disease may require doxycycline.
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Tularemia (Francisella tularensis) – rare transmission via flea bites, especially in prairie dog or rodent cycles. The ulceroglandular form causes a painful skin ulcer and swollen lymph nodes; other forms involve respiratory or systemic involvement. Occurs in North America and parts of Europe and Asia. Streptomycin or gentamicin are first‑line agents; doxycycline is an alternative.
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Yersinia enterocolitica – occasionally isolated from flea vectors; ingestion of contaminated flea material can lead to gastroenteritis with abdominal pain, diarrhea, and fever. Outbreaks are uncommon but documented in rural settings. Supportive care and, for severe cases, fluoroquinolones or third‑generation cephalosporins are recommended.
In addition to infectious diseases, flea bites may provoke localized allergic reactions, resulting in intense pruritus, erythema, and secondary bacterial infection if scratched. Topical corticosteroids and antihistamines alleviate symptoms; secondary infection requires appropriate antibiotics.
Accurate diagnosis relies on clinical suspicion, exposure history, and laboratory confirmation (culture, serology, PCR). Early initiation of targeted antimicrobial therapy is critical to prevent complications and reduce mortality across the spectrum of flea‑borne illnesses.