Animal bites account for approximately 1% of all emergency department visits in the United States (US) each year, with injuries ranging from superficial wounds to severe, disfiguring, or even fatal outcomes. In the US alone, approximately 2 to 5 million animal bites occur each year, with dogs being the most common culprits, followed by cats and, less frequently, wild animals. Dog bites account for approximately 337,000 emergency visits annually. Children are particularly vulnerable, often sustaining injuries to the head and neck due to their smaller stature, while adults and adolescents more commonly experience bites to the hands and arms. While dog and cat bites account for the majority of animal bites encountered, other species, including rats, bats, and monkeys, which account for 1% of cases, also pose risks. Though less common, rat bites can lead to rat-bite fever, an infectious disease affecting individuals with contact with rodents. Bats carry multiple viruses, including rabies, which can be transmitted to humans through bites. Particularly in regions where humans and primates interact closely, monkeys have been known to exhibit aggressive behavior, resulting in bites that can transmit serious infections.  Since dog and cat bites account for over 95% of bite wounds seen in emergency departments, this discussion will focus primarily on these incidents and their common sequelae. Prompt and appropriate wound management is crucial to reduce infection risks, including administering prophylactic antibiotics and, when indicated, rabies and tetanus prophylaxis. The microbial flora in animals' mouths is diverse, encompassing a range of bacteria and viruses. Unfortunately, standard culture techniques taken from animal bite wounds may not always detect all pathogens. This necessitates a thorough evaluation of each bite to assess penetration depth and the extent of injury, which makes diagnosis and treatment challenging.

Rat-bite fever (RBF), caused by Streptobacillus moniliformis, typically presents with fever, rash, and polyarthralgia, but we report an atypical afebrile case in a 36-year-old woman who presented with severe arthralgia and purpuric rash without fever. Laboratory findings revealed leukocytosis, elevated inflammatory markers (CRP 118.77 mg/L, ESR 64 mm/h), and acute kidney injury. Two sets of blood cultures grew Streptobacillus moniliformis, identified by Gram stain, colony morphology, and MALDI-TOF mass spectrometry (Bruker system, score 2.50). Antimicrobial susceptibility testing, performed according to CLSI M100 guidelines, demonstrated sensitivity to penicillin (MIC 0.032 mg/L), ceftriaxone, and other antibiotics. The patient was treated with intravenous penicillin (1.6 million units every 8 h for 14 days) and showed clinical improvement before discharge. This case underscores that fever may be absent in RBF and highlights that, in patients with compatible symptoms (e.g., rash, arthralgia) and potential rodent exposure, blood cultures should be considered even in the absence of fever, especially when other infectious or inflammatory causes are being evaluated, to avoid diagnostic delay.

Rat bite fever, caused by Streptobacillus moniliformis and Spirillum minus, is a zoonotic infection with increasing prevalence as more people keep rats as pets. It is a challenging diagnosis due to a broad range of symptomatology, and its causative organisms are difficult to culture. As such, it may be necessary to be diagnosed presumptively in the appropriate clinical context. This report details a case where diagnosis was presumptively made on a second emergency department presentation after no diagnosis was made on the first presentation. The patient in this case presented with fever, rash, and arthralgias, though presenting symptoms can vary from case to case. While treatable with penicillin or other antibiotics, it may lead to severe complications when diagnosis is delayed or failed. This patient was successfully treated with ceftriaxone followed by cephalexin (chosen due to a penicillin allergy) and made a complete recovery without complication. Taking a complete and thorough history is essential to ensuring that the diagnosis is made and that therapy is initiated in a timely manner.

Erasmus syndrome is an uncommon condition marked by the onset of systemic sclerosis (SSc) due to extended exposure to silica. In this case, we highlight the significant health risks associated with silica exposure in artisanal mining (galamsey), leading to the development of Erasmus syndrome. We present the case of a 33-year-old male artisanal miner with a 14-year work history who presented with a 2-year history of recurrent cough, difficulty breathing, and fever. He later developed hypopigmentation and skin thickening on his face, neck, torso, and knees, along with a productive cough and low-grade fever. He visited multiple healthcare facilities on account of the above complaints. At one of such visits, he was prescribed antituberculosis (TB) medication even though the sputum for GeneXpert was negative. On examination, he was in respiratory distress with an oxygen saturation of 78% on room air and required oxygen via a nonrebreather mask at 10 L/min, which raised the oxygen saturation to 94%, and had bronchial breath sounds in the right lung zones. Vocal resonance was increased bilaterally in the middle lung zones. He had salt-and-pepper dermopathy with tight and adherent skin on his face, chest, back, and knees. He additionally had microstomia, rat bite sign of the fingers, and Raynaud's phenomenon. Antinuclear antibody by indirect immunofluorescence on hep-2 cells was positive (1:320), and Antitopoisomerase 1 antibodies were also positive. Chest CT findings were consistent with complicated silicosis. The patient was diagnosed with Erasmus syndrome and started on immunosuppressive therapy. We highlight the significant health risks associated with silica exposure in artisanal mining (galamsey), leading to the development of Erasmus syndrome. Preventing silica exposure remains crucial, necessitating stringent workplace safety measures and occupational health practices to protect individuals in high-risk professions.

Rat-bite fever (RBF), a zoonotic infection caused mainly by Streptobacillus moniliformis (S. moniliformis), is challenging to diagnose due to the difficulty of isolating the causative pathogen, which can delay the diagnosis or lead to inappropriate treatment. We report herein a case of RBF in which polymerase chain reaction (PCR) testing of a crust specimen from the bite site diagnosed the condition as late as three weeks after the exposure. A previously healthy, 66-year-old, female patient presented with a fever and migratory, asymmetric polyarthritis three weeks after being bitten on her left finger by a rat. Physical examination revealed polyarthritis and a dry, non-purulent crust at the bite site. While blood cultures returned negative, S. moniliformis was isolated from a synovial fluid culture after seven days. Notably, polymerase chain reaction (PCR) testing detected S. moniliformis DNA in both synovial fluid and crust from the bite site, thereby definitively diagnosing RBF despite negative PCR findings for plasma, serum, and urine. This case highlights the diagnostic value of bite-site crust specimens for PCR testing even weeks after exposure and emphasizes the importance of appropriate specimen selection.

Streptobacillus moniliformis is considered normal flora of the upper respiratory tract of rodents and is the predominant cause of rat bite fever in North America. Although patients with rat bite fever oftentimes present with migratory polyarthralgia, cultures of affected joints do not grow bacteria in the vast majority of cases. We present a case of a 32-year-old woman who initially presented with a painful, swollen right index finger proximal interphalangeal (PIP) joint following a bite from her pet rat. After initial treatment with empiric antibiotics did not clear the infection, PIP joint irrigation and debridement revealed culture-positive septic arthritis. This case illustrates the patient's unusual presentation of S. moniliformis infection through septic arthritis of the PIP joint.

Rat bite fever (RBF) is a zoonotic disease caused primarily by Streptobacillus (S.) moniliformis. Norway or brown rats (Rattus [R.] norvegicus) are the natural host for S. moniliformis and carry the bacterium in the nasopharynx without clinical disease. Transmission to humans often occurs through rat bites or scratches, but also through contact with the excreta of infected rats. Although human infections with S. moniliformis occur worldwide, they are rarely diagnosed. For decades, S. moniliformis was the only known member of the genus Streptobacillus. In recent years, however, four additional species were identified, two of which being zoonotic pathogens capable of causing symptoms identical to RBF in humans. The aim of this study was to develop a serological assay covering all known Streptobacillus species. A bead-based multiplex fluorescence immunoassay for S. moniliformis detection has been used for years in routine diagnostics of laboratory rodents. Here, this assay was adapted to enable the detection of antibodies against all currently known Streptobacillus species and tested with sera from experimentally inoculated mice and rats, and with negative sera from laboratory rodents. Using this assay, we broadly examined the prevalence of Streptobacillus spp. reactive antibodies in wild rodents. Transudates from a total of 107 Norway rats, 81 black or roof rats (Rattus rattus) and 110 house mice (Mus musculus) from different husbandries and wildlife populations within Germany were tested. Antibody prevalences of 41% in R. norvegicus and 83% in R. rattus suggest that Streptobacillus spp. are widespread in wild and captive rats in Germany, whereas wild mice seem to be free of infection. Due to its high throughput capacity and multiplex format, the Streptobacillus multiplex serology is well suited for large seroprevalence studies in rodents and has the potential, after adaptation, for use in humans, thereby allowing for the assessment of Streptobacillus infection risk and risk of RBF.

The aim of this paper is to present data on hospitalized patients in Zagreb clinics and hospitals, from 2007 to 2021. This paper is a continuation of our previous paper, but for a different time period. All data were collected from the official patient registry of the Zagreb Antirabies Clinic, which operates within the Reference Center for Rabies at Andrija Štampar Teaching Institute of Public Health. During this period, there were 9960 patients examined for injuries inflicted by animals, of which 98 (0.98%) were hospitalized in different departments and hospitals in Zagreb due to wound severity. All the hospitalized patients were examined to exclude the possible risk of rabies. The official patient registry of the Zagreb Antirabies Clinic is the source of the presented data, which were collected and analyzed retrospectively. We conducted a descriptive analysis. The ages of the hospitalized patients ranged from 17 days to 82 years, 55 (56.12%) were adults, and 43 (43.88%) were children; among the adults, there were 29 (29.59%) men and 26 (26.53%) women, while among the children there were 25 (25.51%) boys and 18 (18.37%) girls. The most common causes of hospitalization after an animal bite were infectious diseases (cat-scratch disease, rat-bite fever) and severity of wounds, which is comparable to the data available from other countries. There is no statistically significant difference in the frequency of hospitalization between children and adults, while dogs are statistically significantly more likely to inflict injuries that result in hospitalization than other animals. However, no specific anatomical location exhibited a statistically significant higher frequency of bites compared to others, as one might expect.

Rodents are recognized as significant reservoirs for a broad range of zoonotic pathogens, including bacteria, viruses, and parasites, many of which have substantial implications for human and animal health. The intensifying interaction between humans and rodent populations, fuelled by urbanization, climate change, and global trade, has amplified the risk of zoonotic disease transmission. This review compiles and examines current knowledge on key rodent-borne bacterial diseases, including leptospirosis, rat-bite fever, plague, salmonellosis, tularemia, Lyme disease, rickettsioses, Babesiosis, and associated parasitic infections such as toxoplasmosis and Chagas disease. Each disease is analyzed in terms of its etiology, transmission, clinical manifestations, diagnostic tools, and treatment options, with a particular focus on the impact of environmental changes. Emphasizing a One Health perspective, this work highlights the importance of interdisciplinary approaches to the surveillance, prevention, and control of rodent-borne zoonoses, particularly in the context of increasing climate variability and anthropogenic pressures.