Merck Manual

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Global Zoonoses*

Global Zoonoses*


Causative Organism

Principal Animals Involved

Known Distribution

Ways Spread to Humans

Signs in Humans

Bacterial Diseases


Bacillus anthracis

Horses, livestock

Worldwide; common in Africa, Asia, South America, eastern Europe

Work-related exposure; foodborne in Africa, Russia, and Asia; occasionally wounds or insect bites; rarely airborne

Skin rash, pneumonia, blood poisoning


Brucella abortus

Cattle, bison, elk, caribou

Worldwide except North America

Work-related and recreational exposure

Fever lasting about a week, progressing to blood poisoning

Brucella melitensis

Goats, sheep, camels


Milk, cheese, contact

Fever lasting about a week with arthritis, progressing to blood poisoning

Brucella suis

Wild and domestic pigs

Northern hemisphere

Rarely airborne

Fever lasting about a week with arthritis, endocarditis; progressing to blood poisoning

Campylobacter enteritis

Campylobacter jejuni

Dogs, cats, poultry


Mainly foodborne, milk, waterborne, or work-related

Inflammation of the intestines, arthritis, blood poisoning

Cat scratch disease

Bartonella henselae, B. quintana



Scratches, bites, “licks”

Enlargement of the lymph nodes to blood poisoning; skin rash in persons with AIDS


Erysipelothrix rhusiopathiae

Pigs, turkeys, pigeons, fish, marine mammals


Work-related, recreational exposure

Skin rash, blood poisoning

Escherichia coli infections (Only some infections are considered zoonotic.)

Certain strains of E. coli, including O157:H7 and others

Cattle, humans

North and South America, Europe, South Africa, Japan, Australia

Eating undercooked ground beef or food or water contaminated with cattle feces

Inflammation of the intestines, diarrhea, abdominal pain, kidney failure


Leptospira interrogans

Common in rodents, dogs


Work-related and recreational exposure; water- and foodborne

Fever, rash, pneumonia, inflammation of the covering of the brain, liver and kidney failure


Listeria monocytogenes

Numerous mammals, birds

Worldwide in cool environments

Raw contaminated milk, cheese, mud, water, and vegetables are infectious

Inflammation of the intestines and the covering of the brain, blood poisoning, fetal infection

Lyme disease (Borreliosis)

Borrelia species

Deer, rodents



Fever, blood poisoning


Mycobacterium avium-intracellulare complex

Many species of mammals, some birds


Primarily waterborne

Lung disease in elderly; spread throughout body in immunocompromised, especially persons with AIDS


Pasteurella multocida and other species

Many species of animals, especially dogs and cats


Wounds, scratches, bites

Wound infections, inflammation of connective tissue, blood poisoning, inflammation of the covering of the brain


Yersinia pestis

Rodents, cats, rabbits, related animals

Areas of Western US, South America, Asia and Africa; rare

Fleas, airborne particles, handling infected animals

Skin rash, enlargement of lymph nodes, pneumonia, blood poisoning

Psittacosis and ornithosis

Chlamydophila psittaci

Parakeets, parrots, other domestic birds

Worldwide; common

Exposure to airborne particles

Pneumonia, blood poisoning

Relapsing fever (Borreliosis)

Borrelia recurrentis

No animal reservoir for louseborne form; wild rodents (tickborne form)

Occasional epidemics

Crushing infected lice, tick bites

Relapsing fever (every 3 to 5 days, up to 10 episodes); blood poisoning


Salmonella enterica

Horses, livestock, dogs, cats, reptiles, amphibians

Worldwide; very common

Foodborne infection, especially in the elderly, infants, or immunocompromised; work-related and recreational exposure

Inflammation of the intestines, blood poisoning

Southern tick-associated rash illness

Borrelia lonestari


Southern US


Bull’s eye-shaped rash, arthritis, blood poisoning

Streptococcal infections

Streptococcus pyogenes, other streptococci

Horses, livestock; occasionally other animals including dogs, cats


Ingestion, especially of raw milk; direct contact

Inflammation of the throat and connective tissues, pneumonia, inflammation of the covering of the brain, arthritis, blood poisoning


Clostridium tetani

Principally herbivores, but all animals may be intestinal carriers


Wound infection and injections

Muscle spasms and contractions (especially facial), seizures, high mortality

Tuberculosis (See also Mycobacteriosis.)

Mycobacterium bovis

Livestock, monkeys

Worldwide; rare in US, Canada, Europe

Ingestion, inhalation, work-related exposure

Skin rash, inflammation of lymph nodes and the intestines

Mycobacterium tuberculosis

Monkeys and other primates; dogs, cats, and other domestic animals, but only rarely


Exposure to animals infected with human tuberculosis

Lung disease, inflammation of lymph nodes and the covering of the brain, widespread organ abscesses


Francisella tularensis

Rabbits, rodents, cats

Polar regions of America, Europe, and Asia

Work-related and recreational exposure; insect bites; ingestion; inhalation

Skin ulcers; inflammation of the throat, lymph nodes, and intestines; pneumonia; blood poisoning


Yersinia pseudotuberculosis

Mammals, birds, puppies, kittens

Temperate zones

Ingestion; recreational exposure

Inflammation of the lymph nodes and intestines

Yersinia enterocolitica

Domestic animals, especially pigs, dogs, cats

Temperate zones

Ingestion; recreational exposure

Inflammation of the intestines with or without blood in stools, arthritis, blood poisoning

Rickettsial Diseases


Ehrlichia chaffeensis

Deer, rodents, horses, dogs

US, Japan


Fever, headache, fatigue, muscle aches

Anaplasma phagocytophilum

Deer, rodents, horses, dogs



Fever, headache, fatigue, muscle aches

Ehrlichia sennetsu




Fever, inflammation of the lymph nodes, blood poisoning, fever

Ehrlichia ewingi




Fever, headache, fatigue, muscle aches

Q fever (Query fever)

Coxiella burnetii

Livestock, cats, dogs, rodents, other mammals, birds

Worldwide; common

Mainly airborne; exposure to placenta, birth tissues, animal excreta; occasionally ticks and milk

Fever, pneumonia, inflammation of the liver and the lining of the heart

Rocky Mountain spotted fever

Rickettsia rickettsii

Rabbits, field mice, dogs

Western hemisphere

Bite of infected ticks, also from crushing tick

Fever, rash, blood poisoning

Spotted fever group

Rickettsia parkeri

Dogs and possibly cats

Western hemisphere

Likely Gulf Coast tick and other related ticks

Fever, mild headache, widespread pain in the muscles and joints, rash

Fungal Diseases

Candidiasis (Moniliasis)

Candida species

Birds and mammals


Direct contact; often person to person

Skin and mucous membrane lesions; blood poisoning and spread to organs in immunocompromised persons


Cryptococcus neoformans

Pigeons, cockatoos, cats, other mammals; principally environmental


Environmental exposure, especially pigeon nests

Self-limiting masses in the lungs; inflammation of the covering of the brain and system-wide spread in immunocompromised persons


Histoplasma capsulatum

Dogs; principally environmental in river valleys


Environmental exposure; grows abundantly in feces of chickens, blackbirds, bats

Flu-like, pneumonia, system-wide spread in immunocompromised persons

Ringworm (Dermatophytosis)

Microsporum, Trichophyton, and Epidermophyton species

Dogs, cats, cattle, rodents, other animals


Direct contact with infected animals or material (bedding)

Skin and hair lesions; rarely, widespread skin involvement in immunocompromised persons


Sporothrix schenckii

Horses, other domestic and laboratory animals, birds; primarily environmental in vegetation (moss) and wood


Work-related contact, including with animals

Skin ulcers may follow course of draining lymphatics of arms and legs; may spread throughout system in immunocompromised persons

Parasitic Diseases—Protozoans


Cryptosporidium parvum

Cattle, other animals


Work-related contact and ingestion; waterborne

Inflammation of the intestine (cholera-like and persistent in immunocompromised persons); inflammation of the bladder


Giardia lamblia

Beavers, porcupines, dogs, other animals

Worldwide; common

Water and less often food; person to person

Inflammation of the intestines; may be persistent

Leishmaniasis (Kalaazar [visceral])

Leishmania donovani and other species

Dogs, wolves, other wild canids

Southern Asia, South America, Africa

Bite of infected sand flies

Fever, enlargement of the spleen and liver, loss of red and white blood cells

Leishmaniasis (skin and mucosal)

Leishmania tropica, L. braziliensis complex

Dogs, wild canids, rodents, marsupials, sloths, other wild mammals

Southern Asia, South America, Africa

Bite of infected sand flies

Raised bumps or ulcers on skin; may spread to oral mucous membranes and persist or recur


Toxoplasma gondii

Mammals, especially cats, livestock, birds

Worldwide; common

Ingestion of feces of infected cats or found in meat or raw milk

Fever and inflammation of the lymph nodes; system-wide, multi-organ disease in immunocompromised persons, including brain abscess; infection of fetus may result in severe damage to central nervous system

Parasitic Diseases—Trematodes (Flukes)

Parasitic Diseases—Cestodes (Tapeworms)

Dipylidiasis (dog tapeworm infection)

Dipylidium caninum

Dogs, cats, fleas


Ingestion of dog or cat fleas

Usually in children, without signs or mild abdominal distress; pieces of worms in stool resemble cucumber seeds

Parasitic Diseases—Nematodes (Roundworms)

Larva migrans, visceral

Toxocara canis, T. cati

Dogs, cats


Ingestion of eggs shed in feces of dogs and cats

Fever, wheezing cough; rash on trunk and extremities; may wax and wane for months; eye involvement (larvae may settle in retina and impair vision)

Trichinosis (Trichinellosis)

Trichinella spiralis and subspecies, T. nativa, T. britovi, T. nelsoni, T. pseudospiralis

Pigs, rodents, horses, wild carnivores, marine mammals

Worldwide, especially subarctic region

Ingestion of pork and flesh of wild animals containing cysts

Inflammation of the lining of the stomach and intestines followed by fever, severe pain in the joints, facial swelling; central nervous system or heart muscle involvement may follow

Parasitic Diseases—Others

Diseases Spread by Insects, Ticks, or Mites

Acariasis (Mange)

Mites of Sarcoptes, Cheyletiella, Dermanyssus, and Ornithonyssus species

Domestic animals


Contact with infected individuals or animals; contaminated clothing

Itchy skin lesions


Cochliomyia hominivorax (screwworm)


Tropical America

Eggs laid in fresh wounds or on skin

Skin wounds; nasal infestations; intestinal infestation; usually mild; some may be shifting and destructive causing burrows and boils

Cuterebra species (rodent or rabbit bot fly)


North America

Eggs laid in fresh wounds or on skin

See above

Dermatobia hominis (human bot fly)


South America, Mexico

Can invade living tissue; eats dead tissue in wounds

See above

Gasterophilus species (equine bot fly)



Can invade living tissue; eats dead tissue in wounds

See above

Tick paralysis

Envenomization of ticks Dermacentor andersoni, D. variabilis, and sometimes Ixodes, Haemaphysalis, Rhinocephalus, and Argas species

Various animals

North America, Australia, South Africa, Ethiopia

Direct contact (attachment) with tick

Inflammation of lining of stomach and intestines followed by nerve paralysis; burning or prickling sensation may be noted

Viral Diseases

Colorado tick fever

Colorado tick fever virus

Ground squirrels, chipmunks, porcupines, small rodents

Western US; common

Tick bites

2- to 3-phase illness with inflammation of the brain and its covering occurring in late phases; abdominal pain and vomiting may occur

Contagious ecthyma (Orf)

Orf virus (parapox)

Sheep, goats, wild hoofed mammals

Worldwide; common

Work-related exposure

Raised rash with sores, usually on hands

Ebola hemorrhagic fever; Marburg hemorrhagic fever

Ebola and Marburg viruses

Primates and bats suspected

Central and southern Africa

Contact with infected animals or animal tissues

Abrupt onset of fever; joint and muscle pain; headache; gastrointestinal signs with vomiting; rash; hepatitis; widespread bleeding 3 to 4 days after onset; death rate 50 to 90% for Ebola, 20 to 30% for Marburg

Hantaviral pulmonary syndrome

Sin Nombre virus, Black Creek Canal virus

Deer mice, cotton rats

US, may be more widespread throughout Americas

Aerosols from rodent excretions and secretions

Fever, joint pain, respiratory failure, decrease in blood cell counts; death rate of 40 to 50%

Hendra virus infection

Hendra virus

Horses, fruit bats

Australia (Queensland)

Direct contact with infected animals or contaminated tissue

Respiratory infection, inflammation of the brain; can be fatal

Hepatitis E

Hepatitis E virus

Pigs, deer, others


Ingestion of contaminated fecal matter or raw or undercooked liver

Fever, gastrointestinal signs, jaundice; may be prolonged; worse in pregnancy

Herpes B virus disease

Cercopithecine herpesvirus 1 (Herpesvirus simiae, B virus)

Old World monkeys

Worldwide; rare

Monkey bites and scratches; work-related exposure

Skin blisters followed by severe encephalitis with seizures, coma, paralysis; fatal in 70% of cases

Influenza type A (swine flu, avian flu, bird flu, Hong Kong flu)

Influenza virus (myxovirus)

Birds, pigs, other mammals; migratory waterfowl serve as reservoirs and carriers for highly pathogenic avian influenza

Worldwide; common

Contact exposure; animals rarely a source

Upper and lower respiratory signs; may progress to influenza, pneumonia, or secondary bacterial pneumonia; seasonally endemic or epidemic


Monkeypox virus

Prairie dogs, Gambian rats, other African rodents, other pet rodents in US, primates

West and central Africa; rare

Contact; aerosols

Usually mild, smallpox-like disease; even milder in those vaccinated for smallpox; swelling of the lymph nodes and other glands prominent

Rabies and rabies-related infections

Lyssaviruses (Rabies virus, Duvenhage virus, Mokola virus, Ibadan shrew virus)

Wild and domestic dogs, ferrets, skunks, mink, civets, bats, other mammals

Worldwide except Australia, New Zealand, Great Britain, Ireland, Scandinavia, Japan, Taiwan; many smaller islands, including Hawaii, are free of infection

Bites of diseased animals; aerosols in closed environments

Tingling of the skin or pain at bite site, fever, joint pain, mood changes progress to excessively rapid breathing, general tingling of the skin, paralysis, seizures, fear of water; death rate more than 99%; other strains of virus very rare, but deadly

Severe acute respiratory syndrome (SARS)


Civet cats most likely

China, southeast Asia

Direct contact suspected, person to person

Fever, joint pain, headache, diarrhea, pneumonia; fatality rate 10%

West Nile virus infection

West Nile virus

Wild birds, horses, other mammals

Eastern and Western hemisphere; common

Mosquito bites; blood transfusion, tissue transplant rarely; may be milkborne

Fever, rash, worse in elderly; inflammation of the brain may be accompanied by paralysis and respiratory failure

Prion Diseases

Variant Creutzfeldt-Jakob disease

Prion protein (likely from bovine spongiform encephalopathy, also known as mad cow disease)


Primarily in England, sporadic cases in France, Ireland, Italy, Canada, US, Japan

Ingestion of beef

Degeneration of nervous system; rapidly fatal

*Many proven zoonoses, including some relatively rare viral infections carried by insects and infections caused by parasitic worms, have been omitted, as well as those diseases caused by fish and reptile toxins.