Tetanus Following Canine Bite in Japan: A Case Report and Literature Review.

BACKGROUND: The incidence of tetanus has significantly declined in developed countries owing to widespread vaccination efforts. However, it remains a threat worldwide, including in Japan, because of the sharp decline in antibody titers against tetanus in adults. Animal bites, including canine bites, are potential sources of tetanus infection. This case highlights the rarity of tetanus caused by canine bites and the need for continued vigilance for tetanus prevention. This case report and literature review aimed to shed light on the clinical course and outcomes of tetanus following a canine bite.

CASE PRESENTATION: A 46-year-old Japanese man with no medical history presented with symptoms of tetanus, such as difficulty in opening his mouth, 19 days after a canine bite on his right hand. He was born and brought up in Japan. He had never been vaccinated against tetanus. Despite washing the wound and receiving human tetanus immunoglobulin (HTIG) and a tetanus toxoid vaccine, the patient developed tetanus. After intravenous metronidazole and HTIG were administered, the symptoms improved gradually. The patient was discharged after a 12-day hospital stay.

DISCUSSION: This is the first reported case of canine bite-induced tetanus in Japan, where tetanus toxoid vaccination is provided routinely. This case highlights the waning immunity in adults and the critical need for education on tetanus immunization, including catch-up immunization, particularly for adults and individuals in high-risk occupations. A review of the existing literature revealed only four cases of tetanus following canine bites between 1889 and 2018. All patients experienced symptom onset between 3 and 19 days post injury. Treatment typically involved HTIG, metronidazole, and toxoid administration. A higher risk of mortality is seen in unvaccinated individuals than in vaccinated individuals, highlighting the critical role of tetanus vaccination.

CONCLUSION: Physicians should consider canine bite-induced tetanus in the differential diagnosis when patients exhibit relevant symptoms.