Rat-bite fever
Rat-bite fever (RBF) is an infectious disease caused by two strains of bacteria: *Streptobacillus moniliformis* and *Spirillum minus*. It primarily spreads through bites or scratches from rodents, as well as contact with their bodily fluids, including secretions from their eyes, nose, or mouth. Individuals living in rat-infested environments, especially in impoverished areas, are at a heightened risk of contracting RBF. The disease can also be transmitted through handling live or dead rats, cleaning rat cages, or even inhaling particles from rat feces.
Symptoms of RBF include fever, headaches, vomiting, skin rashes, and swollen lymph nodes, with the bite area often becoming red and swollen. Diagnosis typically involves blood tests and cultures to detect the presence of the causative bacteria. Treatment is effective with antibiotics if initiated early, but if left untreated, RBF can lead to severe complications affecting vital organs and can be fatal. Preventive measures focus on minimizing exposure to rats and maintaining good hygiene when contact is unavoidable. Understanding RBF is crucial for those in high-risk environments, as awareness and early intervention can significantly influence outcomes.
Rat-bite fever
ANATOMY OR SYSTEM AFFECTED: All
ALSO KNOWN AS: Epidemic arthritic erythema, Haverhill fever, Sodoku, spirillary fever, streptobacillary fever, streptobacillosis
Definition
Rat-bite fever (RBF) is an infectious disease caused by two strains of bacteria, Streptobacillus moniliformis and Spirillum minus. The bacteria are spread through the bite of rodents or through the secretion of rodent fluids.
Causes
RBF primarily develops when rats bite or scratch humans, but infection can also occur simply by touching live or dead rats and by being exposed to secretions from their eyes, nose, or mouth. Additionally, cleaning rat cages and coming in contact with rat urine or feces can cause RBF. Living in rat-infested environments, such as impoverished areas, often leads to RBF, inadvertently ingesting food or water contaminated with rat feces or urine. Breathing in desiccated particles of rat feces may also result in RBF. Gerbils, squirrels, and weasels also carry RBF; furthermore, animals that hunt and ingest rodents, such as cats and dogs, may also infect humans with RBF through a bite, scratch, or secretions.
Risk Factors
Those who live in rat-infested environments are at greatest risk for RBF. Persons living in Asian countries, such as Japan, where the farming of rice attracts large numbers of rats, are more likely to be infected. However, RBF is also present in impoverished North American cities, which often provide a haven for rodent populations. Sanitation and sewage workers are also at high risk of RBF because of daily rodent contact. Laboratory staff are equally vulnerable to RBF because they regularly handle rats and clean their cages; pet store staff are also susceptible to RBF because of increased exposure to pet rats.
Symptoms
Symptoms of RBF include a rash, headache, chills, fever, vomiting, swelling of the lymph nodes, skin irritation, wounds that do not heal, and muscle, joint, and back pain. In particular, the area around the rat bite sometimes becomes reddish purple and swollen and ulcerated. Symptoms usually begin 3 to 10 days after contact with an infected rodent. In some cases, symptoms can develop after the bite or scratch has healed.
Screening and Diagnosis
After a physical examination, blood and culture tests are performed to confirm a diagnosis of RBF. The tests determine if S. moniliformis or S. minus bacteria are in the person’s blood, skin, joint fluid, or lymph nodes. Polymerase chain reaction tests and blood antibody tests aid in the diagnosis of RBF.
Treatment and Therapy
RBF can be treated successfully in early stages of the disease with seven to fourteen days of antibiotics, primarily penicillin, doxycycline, and erythromycin. If left untreated, RBF is extremely dangerous and can damage the heart, brain, and other vital organs; it can sometimes lead to death.
Prevention and Outcomes
Avoiding rat-populated environments is the best way to prevent RBF; however, if contact with rats cannot be avoided, one should always wear gloves when handling them or their droppings; one should also wash his or her hands often. Persons who have been bitten by a rat should treat the wound with antiseptic immediately to help prevent infection and should contact a physician for further care.
Bibliography
"About Rat Bite Fever (RBF)." Centers for Disease Control, 9 July 2024, www.cdc.gov/rat-bite-fever/about/index.html. Accessed 4 Feb. 2025.
Dvorak, Glenda, Anna Spickler, and James Roth. Handbook for Zoonotic Diseases of Companion Animals. Ames: College of Veterinary Medicine, Iowa State University, 2008.
Gratz, Norman. The Vector- and Rodent-Borne Diseases of Europe and North America: Their Distribution, Public Health Burden, and Control. New York: Cambridge University Press, 2006.
Hayashimoto, N., et al. “Isolation of Streptobacillus moniliformis from a Pet Rat.” Journal of Veterinary Medical Science 70 (2008): 493-495.
Peters, C. J. “Infections Caused by Arthropod- and Rodent-Borne Viruses.” In Harrison’s Principles of Internal Medicine, edited by Joan Butterton. 17th ed. New York: McGraw-Hill, 2008.
Suckow, Mark, Steven Weisbroth, and Craig Franklin. The Laboratory Rat. 2d ed. Burlington, Mass.: Academic Press/Elsevier, 2006.