zoonoses and communicable diseases common to ... - PAHO/WHO

226 BACTERIOSESRAT-BITE FEVERICD-10 A25.0 spirillosis; A25.1 streptobacillosisEtiology: Streptobacillus moniliformis and Spirillum minus (S. minor).Rat-bite fever is caused by two different bacteria: Streptobacillus moniliformisand Spirillum minus. Their geographic distribution and clinical picture are differentand thus they will be treated separately.1. Infection due to Streptobacillus moniliformisSynonyms: Haverhill fever, epidemic arthritic erythema, streptobacillary fever.Etiology: Streptobacillus moniliformis is a gram-negative, pleomorphous, nonmotile,nonsporogenic, microaerophilic bacillus 1 to 5 microns long and 0.1 to 0.7in diameter. It occurs in isolated form or in chains 10 to 150 microns long, dependingon the culture medium. Isolation of S. moniliformis requires media with a 20%supplement of serum, blood, or ascitic fluid (Savage, 1984).Geographic Distribution: Worldwide.Occurrence in Man: Very rare. It generally occurs in sporadic cases. Almost halfof all cases are due to bites from laboratory rats. There have also been outbreaks inthe US and Great Britain. The name Haverhill fever derives from an outbreak of“epidemic arthritic erythema” that occurred in 1926 in Haverhill, Massachusetts(USA). The largest outbreak to date occurred in Great Britain. It affected 304 peopleat a girls’ school in a rural area, representing 43% of all the students and personnelat the school (McEvoy et al., 1987).Occurrence in Animals: The agent is isolated from the nasopharynx of a highpercentage of healthy rats. Epizootics have been described in wild and laboratorymice. There have been some outbreaks in turkeys and isolated cases in otheranimals.The Disease in Man: The incubation period lasts from 2 to 14 days after the bitefrom a rat or other rodent. The disease begins with symptomatology similar to thatof influenza: fever, headache, chills, and myalgia. The bite wound heals spontaneouslywithout complications. A maculopapular rash on the extremities as well asmigratory arthralgia and myalgia are common. Polyarthritis is seen in the mostsevere cases. After a short time, body temperature returns to normal, but the fevermay recur. Endocarditis is a possible complication. Mortality reaches 10% inuntreated cases.Haverhill fever has been attributed to the ingestion of milk contaminated by ratfeces. Its characteristics were the severity of vomiting and the incidence of pharyngitis,as well as the usual symptoms of rat-bite fever (Washburn, 1990).The outbreak that affected so many people at the school in Great Britain wasattributed to water contaminated by rats. Many girls were hospitalized for weeks,with severe arthralgia and frequent relapses. There were also complications, such asendocarditis, pneumonia, metastatic abscesses, and anemia (McEvoy et al., 1987).