Unofficial site — data consolidated from public sources (WHO, ECDC, CDC, French health authorities, verified press). View sources.

Glossary · Public health

Zoonosis

Infectious disease naturally transmissible between vertebrates and humans. 60 percent of emerging infectious diseases are of animal origin; hantavirus diseases are among them.

Also called : zoonotic, zoonotic disease, zoonosis Public health

A zoonosis is an infectious disease naturally transmissible between vertebrates and humans. Zoonoses account for 60 percent of emerging infectious diseases and 75 percent of new human pathogens identified over the past thirty years. Hantavirus diseases, of which the MV Hondius episode is one, are an illustration.

Definition and classifications

WHO definition

According to the World Health Organization, a zoonosis is any disease or infection naturally transmissible between vertebrates and humans. It can be caused by viruses, bacteria, parasites, fungi or prions. Modes of transmission are multiple: direct (contact, bite), indirect (a vector such as a mosquito, tick or flea) or environmental (contaminated water, soil, food).

Three main classes

The WHO distinguishes three categories: endemic zoonoses (permanently present in a given geographic area — rabies, brucellosis, leptospirosis), epidemic zoonoses (sporadic emergence in time and space — Ebola, hantavirus, Lassa) and emerging or re-emerging zoonoses (new or rapidly increasing — SARS-CoV-2, Mpox, Andes virus in 2019 and again in 2026).

Public health importance

Global burden

Zoonoses are estimated to cause around 1 billion human cases per year worldwide and roughly 2.7 million annual deaths. These figures are estimates combining endemic zoonoses with high incidence (malaria, leishmaniasis) and lower-incidence emerging episodes with high spread potential.

Accelerated emergence

Several documented factors accelerate the emergence of zoonoses: intensified livestock farming and deforestation, which bring humans closer to wild reservoirs; international trade in live animals; international travel; climate change shifting the ranges of reservoirs and vectors; biodiversity erosion, which favours opportunistic species such as rodents and bats.

The One Health approach

Principle

Faced with the multi-species nature of zoonoses, since the 2000s the WHO has promoted the One Health approach, which integrates human, animal and environmental health in a joint effort. It is carried jointly by the WHO, the FAO (Food and Agriculture Organization of the United Nations), WOAH (formerly OIE — World Organisation for Animal Health) and UNEP (United Nations Environment Programme).

Application to hantavirus diseases

For hantavirus diseases, One Health translates into: surveillance of rodent reservoir populations (density, viral seroprevalence), surveillance of human cases with environmental investigation around each cluster, predictive modelling of risk according to weather and rodent proliferation cycles, and coordinated communication with veterinary and agricultural authorities for prevention in rural areas.

Relevance for the MV Hondius

The MV Hondius episode is a typical illustration of an emerging zoonosis: a pathogen usually transmitted by a wild rodent in South America (Oligoryzomys longicaudatus, the reservoir of Andes virus) infected humans during a trip to an endemic area, then spread on board a vessel on the high seas through human-to-human transmission. This episode simultaneously mobilises the health authorities of 10 countries and concretely illustrates the international coordination that emerging zoonoses require.

Key figures

Standards & references

  • WHO — One Health — Integrated approach combining human, animal and environmental health, promoted by the WHO, FAO and WOAH for the management of zoonoses.
  • International Health Regulations (IHR 2005) — WHO legal framework requiring Member States to report public health events of international concern, including emerging zoonoses.

Frequently asked questions

What is a zoonosis?

According to the WHO, a zoonosis is an infectious disease naturally transmissible between vertebrates and humans. Transmission can be direct (contact, bite), indirect (a vector such as a mosquito or tick), or environmental (contaminated water, soil, food). Hantavirus diseases are zoonoses transmitted mainly by inhalation of aerosols from rodent excretions.

Why are zoonoses emerging?

Several factors accelerate emergence: intensified human-animal contact (industrial farming, deforestation, urbanisation of wild areas), international trade in live animals and animal products, international travel that rapidly spreads pathogens, climate change that shifts the ranges of reservoirs and vectors, and biodiversity erosion that favours opportunistic reservoir species (rodents, bats).

Is hantavirus disease a dangerous zoonosis?

Hantavirus diseases are severe but rare zoonoses. Hantavirus pulmonary syndrome has a case fatality rate of 30 to 40 percent, but animal-to-human transmission remains infrequent (a few dozen to a few hundred cases per year in endemic areas). Andes virus is a notable exception because it is capable of documented human-to-human transmission, which makes it one of the hantavirus diseases most closely monitored by the WHO.

Further reading