Rat-bite fever
| Rat-bite fever | |
| ICD-10 | A25 |
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| ICD-9 | 026 |
| DiseasesDB | 32803 Template:DiseasesDB2 |
| MeSH | D011906 |
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Rat-bite fever Microchapters |
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Rat-bite fever On the Web |
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American Roentgen Ray Society Images of Rat-bite fever |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Historical Perspective
Pathophysiology
Epidemiology & Demographics
Risk Factors
Screening
Causes
Differentiating Rat-bite fever
Complications & Prognosis
Diagnosis
History and Symptoms | Physical Examination | Laboratory tests | Electrocardiogram | X Rays | CT | MRI Echocardiography or Ultrasound | Other images | Alternative diagnostics
Treatment
Medical therapy | Surgical options | Primary prevention | Secondary prevention | Financial costs | Future therapies
Overview
Rat-bite fever is an acute, febrile human illness caused by bacteria transmitted by rodents, rats in most cases. Two types of gram-negative facultatively anaerobic bacteria can cause the infection, which is passed from rodent to human via the rodent's urine or mucous secretions.Rat-bite fever (RBF) is an infectious disease caused by two different organisms, Streptobacillus moniliformis and Spirillum minus. In the United States, Rat-bite fever is primarily due to infection with S. moniliformis. Spirillum minus causes Rat-bite fever cases in countries such as Asia and Africa. S. moniliformis and S. minus are part of the normal respiratory flora of rats. Both organisms may be transmitted to humans through rat bites or scratches. Infection can also result from handling an infected rat, with no reported bite or scratch. Infection with S. moniliformis can also occur through ingestion of food or drink contaminated with rat excrement (Haverhill fever). Other rodents (e.g. mice, gerbils) may also be reservoirs. Person-to-person transmission has not been reported.
Spirillosis
Rat-bite fever transmitted by the gram-negative spirochaete Spirillum minus is more rare, and is found most often in Asia. In Japan the disease is called Sodoku. Symptoms do not manifest for two to four weeks after exposure to the organism, and the wound through which it entered exhibits slow healing and marked inflammation. The fever lasts longer and is recurring, for months in some cases. Joint pain and gastrointestinal symptoms are less severe or are absent. Penicillin is the most common treatment.
Streptobacillosis
The Streptobacillosis form of rat-bite fever is known by the alternate names Haverhill Fever and epidemic arthritic erythema. It is a severe disease caused by Streptobacillus moniliformis , transmitted either by rat bite or ingestion of contaminated products ( Haverhill fever). After a incubation period of around 10 days, Haverhill fever begins with high prostrating fevers, rigors, headache and polyarthralgia. Soon a exanthem appears, either maculopapular or petechial and arthritis of large joints can be seen. The organism can be cultivated in blood or articular fluid. The disease can be fatal if untreataed in 10% of cases due to malignant endocarditis, meningoencephalitis or septic shock. The treatment is with penicillin or tetracycline
Epidemiology and Demographics
Rat-bite fever is rare in the United States. However, since RBF is not a notifiable disease, exact numbers of cases are not known.
Rat-bite fever is not a reportable disease in any state. However, unexplained deaths or critical illnesses or rare diseases of public health importance may be reportable in certain states. If RBF is suspected in a severe illness or death but a diagnosis has not been made, physicians can consider reporting the case to their state or local health department.
Since Rat-bite fever is not a reportable disease, trends in disease incidence are not available. However, recent reports have highlighted the potential risk for RBF among persons having contact with rats at home or in the workplace.
Risk Factors
Persons who are at risk for infection include those who work with animals in labs or pet stores and persons living in dwellings infested with wild rats. People who have pet rats may also be at risk for infection.
Symptoms
Initial symptoms are non-specific and include fever, chills, myalgias, arthralgias, headache, vomiting. Patients may develop a maculopapular rash on the extremities or septic arthritis 2-4 days after fever onset. The incubation period typically ranges from 2-10 days. If not appropriately treated, severe manifestations may include endocarditis, myocarditis, meningitis, pneumonia and sepsis. In rare cases, death occurs.
Diagnosis
The findings of rash, fever, and arthritis in individuals with a history of rat exposure suggest the diagnosis of Rat-bite fever.
Diagnosis of S. moniliformis is typically made by isolating the organism from blood or synovial fluid. Specific media and incubation conditions should be used. In the absence of a positive culture, identification of pleomorphic gram-negative bacilli in appropriate specimens supports a preliminary diagnosis. Since the organism does not grow in artificial media, diagnosis of S. minus is made by identifying characteristic spirochetes in appropriate specimens using darkfield microscopy or differential stains.
Risk Stratification and Prognosis
Severe complications such as endocarditis, myocarditis, pericarditis, pneumonia, meningitis, and focal organ abscesses may occur. Rapidly fatal cases have been reported. Untreated RBF is associated with a mortality of 7%-10%. With appropriate antimicrobial therapy, the clinical course may be shortened and severe complications may be prevented.
Treatment
Responds to penicillin antibiotics or where allergic to this erythromycin or tetracyclines for repectively streptobacillary or spirillary infections.
Prevention
Whilst obviously preventable by staying away from rodents, otherwise hands and face should be washed after contact and any scratches both cleaned and antiseptics applied.
References
http://www.cdc.gov/ncidod/dbmd/diseaseinfo/ratbitefever_g.htm
External links
- Rat-bite fever description
- Case report of fatal incidence in the USA
- Rat-bite fever (healthAtoZ.com)
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