Which rat is the most dangerous in the world? - briefly
The black rat (Rattus rattus) poses the greatest threat worldwide because it is the primary carrier of plague‑inducing bacteria and numerous other pathogens. Its close association with human settlements amplifies the risk of disease transmission.
Which rat is the most dangerous in the world? - in detail
The rodent that poses the greatest threat to human health worldwide is the black rat (Rattus rattus). It carries Yersinia pestis, the bacterium responsible for plague, and serves as a primary vector for murine typhus, leptospirosis, and several hemorrhagic fevers. Historical records link the species to three of the four major plague pandemics, confirming its capacity to spread lethal pathogens across continents.
The Norway rat (Rattus norvegicus) ranks second in danger level. It thrives in urban sewers and agricultural settings, transmitting hantavirus, leptospirosis, and salmonellosis. Its larger size and aggressive behavior increase the risk of bites and contamination of food supplies.
Additional species contribute regionally:
- Polynesian rat (Rattus exulans): Introduced to many Pacific islands, it disrupts native ecosystems and carries parasites that affect indigenous bird populations.
- Brown rat (Rattus tanezumi): Common in Southeast Asia, it spreads murine typhus and serves as a reservoir for rodent-borne viruses.
- Australian bush rat (Rattus fuscipes): Though less associated with human disease, it competes with native fauna and can transmit leptospirosis in rural areas.
Criteria for assessing danger include:
- Pathogen carriage: Number and severity of diseases transmitted.
- Geographic distribution: Global presence versus localized range.
- Human contact frequency: Habitat overlap with settlements.
- Ecological impact: Ability to outcompete native species and alter ecosystems.
Considering these factors, the black rat emerges as the most hazardous rodent globally, followed closely by the Norway rat, with other species presenting significant but more regionally confined threats.