Streptobacillus bacteria is a genus of a gram-negative bacteria which sometimes tends to form filaments. It tends to be the cause of Haverhill fever, which is a form of rat-bite fever, within humans and possibly even dogs and cats. Streptobacillus bacteria can also cause acute septicemia or chronic disease, characterized by arthritis in mice. The bacteria is made up of a group of rod-shaped bacteria that remain loosely attached end-to-end within a long chain, which is due to the failure of daughter cells to separate after the initial cell division.

Rat-bite fever most commonly occurs amongst laboratory workers handling lab rats throughout their day to day work, and among people who live in poor conditions with rodent infestation problems. Children are most likely to be bitten by rodents and subsequently infesting their home, and are therefore most likely to contract rat-bite fever. Other animals that can carry the types of bacteria responsible for this illness include mice, squirrels, weasels, dogs, and even cats. One of these causative bacteria can provoke the same illness if it is ingested, for example the bacterium found in unpasteurized milk.

Rat bite fever is related to streptobacillus, as it is caused by streptobacillus moniliformis, and is a systemic illness commonly characterized by fever, rigors, and polyarthralgias. If rat bite fever is left untreated, there is a risk of death, as the mortality rate is 10 percent. Unfortunately, it is hard to recognize a potential rat bite infection, and its initial presentation along with difficulties in culturing its causative organism produces a significant risk of delay or failure when it comes to doctors diagnosing it. Since there its been an increase in the popularity of rats and rodents as pets, there has been increased attention given to rat bite fever when it comes to diagnosing an infection. In streptobacillary rat bite fever, which is the form found in the United States, diagnosis may be made by taking a sample of blood or fluid from a painful joint from within the potential patient. Once the sample is taken to a laboratory, it is allowed to culture, which in turn allows for the growth of organisms. Once these samples are examined under a microscope, an identification of streptobacillus moniliformis can be made.

Shots of procaine penicillin G or penicillin V can be administered by mouth, and is affective against both streptobacilli and spirillary rat bite fever. For those individuals allergic to penicillins, erythromycin may be administered orally for streptobacillary infection, and tetracycline by be administered by mouth for spirillary infection. Prevention involves avoiding contact with those animals capable of passing on the causative organisms. Because streptobacilli rat-bite fever can occur after drinking contaminated milk or water, only pasteurized milk, and water from safe sources, should be ingested. Always remember to monitor the source of food you consume, and do not come into contact with rats or rodents. Always consult a physician before starting a treatment for a streptobacillus bacteria infection.