MSD Manual

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Global Zoonotic Diseases: Bacterial and Rickettsial Diseases

Global Zoonotic Diseases: Bacterial and Rickettsial Diseases

Disease in Humans

Causative Organism

Animals Involved

Geographic Distribution

Probable Means of Transmission to Humans

Clinical Manifestations in Humans

Bacterial Diseases

Bacillus anthracis

Mainly noted in production animals (cattle, sheep, goats, horses, water buffalo, camelids) and wild herbivores; however, virtually all mammals are susceptible to high doses. A few cases have been noted in birds.

Worldwide but distribution is focal; common in Africa, Asia, South America, Middle East, parts of Europe

Occupational contact exposure (abraded skin, mechanical transmission by biting flies, other routes); ingestion or foodborne, rarely airborne

Early signs vary with route of inoculation; papule to ulcerative skin lesions; mild to severe gastroenteritis ± hematemesis, bloody diarrhea, ascites (abdominal GI form); sore throat, dysphagia, fever, neck swelling, mouth lesions (oropharyngeal GI form); pneumonia; all may progress to sepsis, meningitis; untreated cases fatal in 5%–30% (cutaneous) to 100% (inhalation)

Arcobacter infections

Arcobacter butzleri, A cryaerophilus, A skirrowii, possibly others

Poultry, cattle, pigs, sheep, horses, shellfish; some studies have detected these organisms in dogs and cats


Ingestion of contaminated water, undercooked meat (especially poultry) has been suggested

Gastroenteritis; bacteremia, mainly in patients with chronic illnesses; endocarditis, peritonitis; emerging and incompletely understood

Bordetella bronchiseptica, B hinzii

B bronchiseptica in dogs, rabbits, cats, pigs, guinea pigs, other mammals; B hinzii mainly in poultry, uncommonly mammals (eg, rabbits, rodents)

Worldwide; uncommon in humans

Exposure to saliva or sputum, aerosols

Sinusitis, bronchitis, pertussis-like illness; pneumonia and disseminated disease (eg, endocarditis, peritonitis, meningitis), usually in immunocompromised; biliary infections; wound infection; abscesses

Lyme disease (Lyme borreliosis)

Borrelia burgdorferi sensu lato complex (B burgdorferi sensu stricto, B garinii, B afzelii, B spielmanii, possibly others)

Wild rodents, insectivores, hedgehogs, hares, other mammals; birds are reservoirs for some agents (eg, B garinii); possibly some lizards

Agents exist worldwide where Ixodes ticks are found; human cases have been reported in North America, Europe, Australia, parts of Asia, Amazon region of South America

Nonspecific febrile illness early; erythema migrans ("target-like") skin lesions in many; may progress in some humans to arthritis, neurologic, cardiac, and/ or skin signs (acrodermatitis chronica atrophicans); syndromes may vary with infecting agent

Tickborne relapsing fever

B recurrentis, B crocidurae, B turicatae, B hermsii, B persica, B hispanica, others; some species such as B duttoni are human pathogens and not zoonotic

Wild rodents, insectivores, possibly birds

Africa, Asia, Europe, Americas; species varies with region

Tick bites (mainly Ornithodoros spp)

High fever, malaise, headache, myalgia, chills; neurologic signs or abortion possible; jaundice, epistaxis, major organ dysfunction possible; recurring episodes, often milder, after a symptom-free period; death in 2%–5%

Borrelia miyamotoi disease

Borrelia miyamotoi

Rodents, birds, possibly larger mammals

Asia, Europe, North America, probably other locations

Tick bites (Ixodes spp)

Fever, nonspecific flu-like signs including GI signs in some, rash, thrombocytopenia; meningoencephalitis in immunocompromised

Brucella abortus

Cattle, water buffalo, American bison, African buffalo, elk are reservoir hosts; numerous mammalian spillover hosts (eg, deer, sheep, goats, camels, South American camelids, pigs, canids, felids, horses)

Once worldwide, now eradicated or uncommon in domestic animals in some countries or regions; reservoirs in wildlife in some disease-free areas including the US

Exposure to birth products from animals, ingestion (especially unpasteurized dairy products or undercooked meat), contact with mucous membranes and broken skin, accidental inoculation of strain 19 vaccine; rare instances of person-to-person transmission (eg, assisting at a birth from an infected woman, in a blood transfusion, or during sexual intercourse)

Extremely variable, subacute and undulant to sepsis; often nonspecific febrile illness with drenching sweats early; arthritis, spondylitis, epididymo-orchitis, endocarditis, neurologic and , various other syndromes if chronic; case fatality 1%–2% in untreated

B melitensis

Goats, sheep are the primary hosts; can infect various mammalian spillover hosts (eg, cattle, water buffalo, camelids, dogs, pigs, wild ungulates)

Parts of Asia, Africa, Middle East, Europe and Latin America including Mexico

As for B abortus; accidental inoculation of Rev 1 vaccine

As above; this species is considered highly pathogenic for humans

B suis biovars 1–4; biovar 5 has not been reported in humans

Swine and wild pigs (biovars 1, 2, 3), European hares (biovar 2 in Europe, possibly biovar 1 in South America), reindeer and caribou (biovar 4); B suis also in some other mammals

Biovars 1 and 3 worldwide in swine-raising regions except eradicated or nearly eradicated from domestic pigs in some countries; biovar 2 in wild boar in Europe; biovar 4 in Arctic regions of North America and Eurasia

As for B abortus; food sources may include uncooked caribou bone marrow (biovar 4)

As above

B canis

Dogs; evidence of infection in wild canids including coyotes, foxes

Worldwide except in a few regions (Australia, New Zealand); not common in humans

Probably as for B abortus; close contact, especially with animals that recently aborted or gave birth

Probably as above

B ceti and ST27 genotype from marine mammals, possibly B pinnipedialis

Marine mammals (B ceti mainly in cetaceans, B pinnipedialis mainly in pinnipeds)

Probably occur in most or all marine environments

Laboratory exposure; sources of other infections unknown (possibly contact with animals or exposure to seawater, seafood); rare or underdiagnosed in humans

Few cases known: mild to severe febrile illness, similar to that due to other Brucella spp; neurological signs occurred in some patients

B neotomae, B inopinata; additional species of Brucella maintained in wild animals might also be human pathogens

B neotomae in desert wood rat (Neotoma lepida) and possibly other rodents. Host of B inopinata unknown.

Uncertain. Two human cases due to B neotomae were acquired in South America


Probably similar to cases due to other species of Brucella. Two cases due to B neotomae had neurological signs as well as other brucellosis symptoms. B inopinata was isolated from 1) an infected breast implant, possibly after a systemic infection, and 2) the lungs in a case of chronic pneumonia.

C jejuni, C coli, occasionally other species; some strains of C jejuni seem to have broader host ranges than others

Poultry, cattle, swine, dogs, cats, rodents, other mammals, wild birds


Foodborne (especially poultry and other meats, unpasteurized dairy products); waterborne; contact with infected animals (fecal-oral route)

Gastroenteritis from mild cases to fulminating or relapsing colitis; occasional sequelae such as reactive arthritis; occasionally, other syndromes, including sepsis

Campylobacter fetus infection

C fetusfetus (most cases), C fetustestudinum; possibly C fetusvenerealis

C fetusfetus and Cvenerealis in cattle, sheep, goats (human-adapted lineages also seem to exist); C fetustestudinum in reptiles


Probably direct contact or ingestion; often unknown

Opportunist; sepsis, meningitis, endocarditis, abscesses, other systemic infections in elderly, immunocompromised, or infants; abortions, preterm births in pregnant women, neonatal sepsis; gastroenteritis not prominent in most cases

Capnocytophaga infection

C canimorsus, C cynodegmi, C canis (rare), possibly others

Dogs, cats

Probably worldwide

Bites or scratches

Fever, localized infections to bacteremia or sepsis, endocarditis, meningitis; often in immunocompromised or elderly

Cat scratch disease

Bartonella henselae; B clarridgeiae and other Bartonella species also implicated rarely in cat scratch disease or other conditions (eg, endocarditis)

Cats and other felids; other Bartonella spp in canids, rodents, rabbits, other animals


Often associated with scratches, bites, especially from cats; potential for other exposures to broken skin via saliva; exposure of conjunctiva

Lymphadenopathy (may be absent in elderly), fever, malaise, skin lesions at inoculation site in immunocompetent, usually self-limiting with complications (eg, endocarditis, neuroretinitis, neurologic disease) uncommon; inoculation into eye results in conjunctivitis ± ocular granuloma and local lymphadenopathy; risk of bacteremia, disseminated disease, bacillary angiomatosis in immunosuppressed

Chlamydia abortus; C felis, C suis, C pecorum involved or suspected in a few cases

C abortus reservoirs are sheep, goats; C pecorum found in ruminants, horses, pigs, others; C felis mainly in cats; C suis mainly in suids; Chlamydia spp also infect mammals other than their usual hosts, occasionally reptiles, amphibians, possibly birds

C felis, C suis, C pecorum are cosmopolitan; C abortus in most sheep-raising areas but not Australia or New Zealand

Contamination of mucous membranes, inhalation and possibly other routes after contact with animals; C abortus in high concentrations in birth products but chlamydiae also occur in other secretions and excretions

C abortus: mainly abortions, stillbirths, preterm births, often associated with illness including septicemia in mother; respiratory disease and possibly other conditions in nonpregnant (few cases); other chlamydiae suggested to be involved rarely in various illnesses including C felis in conjunctivitis suspected agent of keratoconjunctivitis, also implicated in other conditions (controversial)

Clostridium difficile; some genotypes in animals are shared with humans and implicated as potential zoonoses

Cattle, pigs, dogs, and other species


Possible zoonosis; from contact or ingestion in contaminated meat; also from environment and contact with infected humans

Gastroenteritis, varying in severity from diarrhea to fulminant colitis, usually in conjunction with antimicrobial use

Clostridium perfringens, type A (most common), C, or D; environmental or endogenous source, with some potential for zoonotic transmission

Domestic and wild animals, humans


Foodborne (usually type A); nonfood-associated intestinal infection; wound contaminant, usually environmental; may be endogenous in debilitated from GI or urogenital tract

Foodborne gastroenteritis, usually brief, self-limited except in debilitated; nonfood-related intestinal infection with prolonged diarrhea, sometimes bloody, mainly in elderly after antimicrobials; life-threatening necrotic enteritis, often in debilitated; gas gangrene, sepsis; necrotic enteritis, gas gangrene, sepsis are fatal if not treated

Corynebacterium ulcerans, C pseudotuberculosis, and C bovis infections

C ulcerans, C pseudotuberculosis, C bovis

C ulcerans in cattle, pigs, small ruminants, dogs, cats, ferrets, other domestic and wild animals; C pseudotuberculosis in sheep, goats, cattle, horses, camelids, other mammals; C bovis in cattle, colonies of immunocompromised laboratory rodents

Probably worldwide; uncommon in humans but may be increasing

Direct contact, consumption of unpasteurized milk products

Acute upper respiratory illness with sinusitis, sore throat, tonsillitis, or more severe pharyngitis resembling diphtheria (pseudomembranous pharyngitis); cardiorespiratory complications including pneumonia possible; peritonitis; isolated skin infection; ocular disease (C bovis) and other localized conditions; some cases serious or fatal

Dermatophilus congolensis

Cattle, horses, deer, sheep, goats, other mammals

Worldwide, especially in warmer regions

Usually direct contact with lesions; mechanical transmission on fomites possible

Pustular desquamative dermatitis, other skin lesions

Enterohemorrhagic and enteroaggregative Escherichia coli infections

E coli O157:H7, O157:H-, members of O26, O55, O91, O103, O111, O121, O145 and other serogroups

Especially cattle, sheep; also found in goats, bison, camelids, cervids, pigs, lagomorphs, many other of mammals; sometimes shed by birds


Ingestion of undercooked meat (especially ground beef), unpasteurized milk products, vegetables, other food sources or water contaminated with feces; direct contact with feces, animals (especially ruminants) or contaminated fomites

Diarrhea or hemorrhagic colitis; a minority of patients with hemorrhagic colitis develop hemolytic uremic syndrome (HUS); case fatality rate for HUS is 3%–5%, higher in some populations (eg, 1%–10% in children, up to 50% in elderly)

Erysipelothrix rhusiopathiae

Swine, sheep, cattle, rodents, marine mammals; many other domestic and wild mammals and marsupials, birds (including poultry), reptiles, fish, mollusks, crustaceans


Contact with animal products; via skin, usually after scratch or puncture wound; contaminated soil (survives for weeks to months)

Localized cellulitis, usually self-limiting, often on hands; generalized skin lesions (uncommon); septic arthritis, often in finger joints near skin lesion; endocarditis (with high mortality, 38%); generalization with sepsis, other syndromes uncommon and often in immunocompromised

Burkholderia mallei

Equids are reservoirs; many other domesticated and wild mammals also susceptible to infection, clinical cases reported occasionally, especially in felids

Middle East, Asia, Africa and South America

Contact with infected animals, tissues through broken skin, mucous membrane, ingestion, inhalation

Mucous membrane or skin lesions; pneumonia and pulmonary abscess; sepsis; chronic abscesses, nodules, ulcers in many organs, weight loss, lymphadenopathy; case fatality rate varies with form, but > 95% in untreated septicemia and 90%–95% in untreated pulmonary disease

Helicobacter infection

H pullorum, H canis,H suis, other species suspected as zoonoses

Poultry (H pullorum), rodents (H pullorum and other species), pigs (H suis), dogs (H canis), many other mammals

Uncertain; possibly ingestion of undercooked meat or direct contact

Gastroenteritis or diarrhea, liver disease; cellulitis; bacteremia in immunosuppressed patients

Mycobacterium leprae

Armadillos; nonhuman primates (rare)

Armadillos in parts of southern US, Mexico, South America; nonhuman primates in Africa, possibly other locations; only human reservoirs in other areas

Transmission of animal leprosy to humans likely

Various skin lesions, sensory nerve lesions and deficits, nasal mucosal lesions; mild, self-limiting to progressive destruction

Leptospira spp

Domestic and wild animals; reservoir hosts include rodents, dogs, cattle, pigs, farmed red deer, others


Occupational and recreational exposure, or exposure to rodent-contaminated material in urban locations; especially skin, mucous membrane contact with contaminated urine, infected fetuses, or reproductive fluids; water- and foodborne

Asymptomatic to severe, sometimes biphasic; nonspecific febrile illness followed by aseptic meningitis or icteric form (especially liver, kidney, CNS involvement, hemorrhages possible); pulmonary hemorrhage and edema, other syndromes; uveitis can be sequela; case fatality rate varies with syndrome (uncommon in aseptic meningitis, 5%–15% in icteric form, 30%–60% in severe pulmonary form)

Listeria monocytogenes, rarely Listeria ivanovii or other species of Listeria

Numerous mammals including marsupials, some birds and reptiles; subclinical fecal shedding has been reported in fish and amphibians; crustaceans can be contaminated


Most often foodborne, especially unpasteurized dairy products and various ready-to-eat refrigerated foods (eg, patés, deli meats); however, also many other sources including raw meat and fish, vegetables and fruits, foods contaminated after processing; ingestion of contaminated water, soil; direct contact with infected animals (via mucous membranes, broken skin as well as ingestion); transmission can occur between newborns in hospitals but person-to-person transmission otherwise absent or negligible

Acute, self-limited febrile gastroenteritis or mild, flu-like illness; ocular disease, conjunctivitis; abortion, premature or septicemic newborn if infected during pregnancy; meningitis, meningoencephalitis, septicemia in elderly, immunosuppressed, and infants; bone and joint infections in humans with implants; papular or pustular rash ± fever, chills in healthy adults after handling infected fetuses or other heavily contaminated source; occasionally other syndromes

Melioidosis Melioidosis (pseudoglanders)

Burkholderia pseudomallei (other species of soil-associated Burkholderia, (eg, B oklahomensis sp nov in North America, rarely linked to similar human diseases)

Sheep, goats, swine; occasional cases in many other terrestrial and aquatic mammals; also reptiles; some birds including psittacines, ratites, chickens; tropical fish

Mainly reported in parts of Asia and northern Australia; however, organisms or cases also documented in Africa, South America, Middle East, Caribbean; B pseudomallei is not known to exist in North America but a few cases that appeared to be indigenous were documented, source of organism uncertain

Via broken skin, inhalation, and ingestion; organisms live in soil and surface water; most cases are acquired from environment; direct transmission from animals is possible

Mimics many other diseases; acute localized infections, including skin lesions, cellulitis, abscesses, corneal ulcers; pulmonary disease, septicemia, internal organ abscesses; often occurs in immunocompromised; case fatality rate varies with form, > 90% in untreated septicemia

Methicillin-resistant Staphylococcus aureus (MRSA) infections

S aureus that carry mecA or mecC gene; some strains maintained in animals (eg, production animals-associated CC398), other strains mainly in humans but animals can become carriers

Pigs (major reservoirs for production animals-associated strain CC398); cats, dogs mainly acquire strains from humans; MRSA also reported in other mammals, including horses, cattle; birds, including poultry, psittacines; turtles

Worldwide; can be reverse zoonosis or zoonosis; major strains in animals can vary with region

Usually by direct contact (typically with subclinically affected carrier animals); other routes also described; can be nosocomial in hospitals

Opportunist; localized skin and soft-tissue infections, invasive disease including septicemia, toxic shock syndrome; mortality varies with syndrome and success in finding antimicrobial

Mycobacterium avium complex

Many species of mammals, some birds


Environmental, mainly from water, or soil; infection common to humans and animals

Soft-tissue and bone infections; cervical lymphadenitis; pulmonary disease, often in immunocompromised or those with preexisting lung conditions; disseminated in immunocompromised, especially AIDS patients with uncontrolled disease

Mycobacteria other than tuberculosis (eg, M simiae, M kansasii, , M genavense, M chelonae, M marinum, M ulcerans, others)

Ruminants; swine, cats, dogs, other mammals, amphibians, reptiles (uncommon), fish; species of Mycobacterium spp varies with host

Worldwide; distribution varies with the organism

Environmental, from water or soil

Same syndromes as M avium complex; some organisms tend to be associated with certain syndromes (eg, M marinum, M ulcerans, with ulcerative or nodular dermatitis)

Yersinia pestis

Rodents (eg, squirrels, prairie dogs, rats) and lagomorphs (pikas in Asia) are main reservoir; many mammals can be incidental hosts; cats and wild felids especially susceptible

Foci in North and South America, Asia, Middle East, and Africa

Flea bites, aerosols, handling infected animals or tissues (contact with broken skin or mucous membranes), bites, eating uncooked infected tissues

Febrile flu-like syndrome with swollen, very painful draining lymph node(s) (bubos); pneumonia; GI signs associated with foodborne outbreak; sepsis can occur in either bubonic or pneumonic form; case fatality rate in untreated 40%–70% (bubonic) to 100% (pneumonic); < 5% mortality if bubonic form treated early

Chlamydia psittaci, possibly other avian chlamydiae (eg, C gallinacea, C avium)

C psittaci in psittacines, pigeons, poultry, game birds, ratites and other domestic or wild birds; occasionally in mammals, possibly reptiles; C gallinacea in various poultry; C avium in pigeons, other birds


Direct contact with birds, inhalation of contaminated dust, feathers or aerosolized secretions or excretions from environment

Influenza-like febrile illness, with or without respiratory signs, that may progress to pneumonia; reproductive losses (abortion, premature birth); keratoconjunctivitis; endocarditis, myocarditis, meningoencephalitis, hepatitis, renal disease and other organ dysfunction, sepsis possible in severe cases; sometimes fatal if untreated, < 1% mortality with treatment

Rat bite fever

Streptobacillus moniliformis

Rodents, especially rats; might also be transmitted by carnivores (eg, dogs, cats, ferrets), which are probably infected or transiently colonized from rodents

Probably worldwide

Bites and scratches; handling or kissing a rodent, exposure to rodent urine; can be waterborne or foodborne

Febrile illness, often with rash; GI signs possible and especially common when foodborne polyarthritis/ polyarthralgia (usually but not always sterile) common, can persist for several months or more; other complications including hepatitis, endocarditis, focal abscesses, sepsis possible if untreated; overall case fatality rate 7%–13% if untreated

Spirillum minus

as above

Seems to be common only in Asia but cases have been attributed to this organism on other continents

Mainly bites and scratches

As above; however, indurated, often ulcerated lesion at inoculation site; can relapse; some (minority) may have distinctive rash (large violaceous or reddish macules); polyarthritis is uncommon; overall case fatality rate 7%–10% if untreated

Salmonella enterica and S bongori (> 2,500 serovars)

Widespread in mammals, birds, reptiles, amphibians, including domestic species; also in crustaceans; higher-risk pets for human exposure may include reptiles, amphibians, young poultry, some exotic mammals, including hedgehogs


Foodborne infection or fecal-oral; some cases of occupational and recreational exposure

Gastroenteritis to sepsis; focal infections possible; especially severe in the elderly, young children, or immunocompromised

Streptococcal infections

Streptococcus spp, including S suis, S equi zooepidemicus, S canis, S iniae, S halichoeri, probably others

S suis in swine and wild boar; S equi zooepidemicus in horses; S canis in dogs, cats; S iniae and S halichoeri in fish (S halichoeri has affected various marine and terrestrial mammals including dogs, mink, farmed foxes, wild badger); each species can also be found in other animals

Streptococcus spp worldwide, but some organisms documented in limited locations (eg, S halichoeri in Europe)

Ingestion, especially of unpasteurized dairy products, undercooked animal tissues; direct contact, often through broken skin

Skin and soft-tissue infections; pharyngitis; other conditions, including pneumonia, meningitis, arthritis, endocarditis, streptococcal toxic shock syndrome, sepsis

Mycobacterium bovis

Cattle, bison, African buffalo, some cervids (elk, white-tailed deer), brushtail opossums, European badgers, wild boar, Kafua lechwe can be reservoirs; many other mammals can be spillover hosts, rare reports in birds

Once worldwide, now eradicated or rare in some countries

Ingestion (unpasteurized dairy products, undercooked meat), inhalation, contamination of breaks in the skin

Skin lesions, cervical lymphadenitis pulmonary disease; can also affect genitourinary tract, bones, joints, CNS, intestinal tract and other sites; disseminated disease possible, especially in immunocompromised or young children; slow progression in most healthy humans and low mortality if treated, but CNS disease, disseminated disease, and immunocompromised patients have higher fatality rates

Mycobacterium caprae

Goats are main reservoir; cattle, wild red deer may also maintain organism; also infects other mammals (eg, sheep, pigs, wild boar, horses, cervids, camels, foxes, zoo animals)

Reported mainly in Europe; also found in China, North Africa and may occur in other countries

Probably similar to M bovis

Similar to M bovis

Mycobacterium microti

Rodents, insectivores are reservoir; can occur in many other wild or domestic animals including cats, dogs, ferrets, production animals

Widely distributed

Probably similar to M bovis

Probably similar to M bovis

Mycobacterium orygis

Oryx, African buffalo, waterbuck, rhinoceros, nonhuman primates and other species

Africa, southern Asia, Middle East

Probably similar to M bovis

Probably similar to M bovis

Mycobacterium pinnipedii

Seals and sea lions are usual hosts; also reported in cetaceans and various terrestrial mammals (eg, cattle, camelids, nonhuman primates)

Coasts of Europe, South America, New Zealand, Australia, probably other locations

Probably similar to M bovis

Probably similar to M bovis

Francisella tularensis (some subspecies of this organism seem to be more virulent than others); other species of Francisella (eg, F hispaniensis, F philomiragia) can also cause illness but might mainly affect the immunocompromised

Lagomorphs, rodents, cats, sheep, many other mammals, birds, reptiles, fish; often in wild animals

F tularensistularensis almost exclusively in North America; F tularensisholarctica in Northern Hemisphere and Australia; F tularensismediasiatica in Central Asia; F tularensisnovicida reported in North America, Thailand; F hispaniensis in Europe (Spain) and Australia

Contact with mucous membranes, broken skin; insect bites (tabanids, mosquitoes, hard ticks); fomites; ingestion in food or water; inhalation

Nonspecific febrile illness, lymphadenitis; ulcerative skin lesions, exudative pharyngitis and stomatitis, conjunctivitis, gastroenteritis, respiratory signs or pneumonia, sepsis; case fatality rate 5% (localized disease, untreated) to > 50% (untreated typhoidal form or severe respiratory disease); 1%-–3% case fatality overall when treated


Vibrio parahaemolyticus

Marine and estuarine shellfish, fish; also environmental in aquatic environments


Ingestion, wound infections

Gastroenteritis; dysentery (especially in some geographic regions); wound infections (mild to severe, including necrotizing fasciitis); sepsis; severe wound infections and sepsis usually in immunocompromised or those with liver disease (case fatality rate for sepsis 29%)

V vulnificus

Marine shellfish, crustaceans (eg, shrimp), fish; also environmental in aquatic environments

Worldwide; human cases have been reported in North America, Europe, Asia

Ingestion (often raw oysters), wound infection from water or handling hosts

Wound infections from mild, self-limited lesions, bullae to cellulitis, myositis; necrotizing fasciitis; gastroenteritis; sepsis, usually in immunocompromised or those with liver disease, other debilitating illnesses; case fatality rate for sepsis > 50%, and up to 25% for wound infections


V cholerae O1/O139 (epidemic strains)

Oysters, crabs, shrimp, mussels can act as a reservoir for organisms although most cases are acquired from humans

Rare or absent to epidemic in different regions; one focus along US Gulf Coast in shellfish


Mild to severe, voluminous diarrhea, vomiting, dehydration; severe cases fatal if untreated; however, low mortality if treated

V cholerae non-O1/O139 (nonepidemic strains)

Oysters, other seafood, fish; also environmental in aquatic environments


Ingestion, wound infection

Gastroenteritis, usually mild and self-limited; wound infections; septicemia, usually in immunosuppressed or those with liver disease (case fatality rate for sepsis 47%–60% or higher)


Yersinia pseudotuberculosis

Many species of mammals, including production animals, dogs, cats, lagomorphs, rodents, wild and zoo mammals, birds, possibly reptiles

Agent probably worldwide; prevalence may vary between regions

Ingestion of contaminated water, food (including meat, vegetables); fecal-oral (animal contact); dog bite (rare)

Gastroenteritis (enterocolitis); pseudoappendicitis (with mesenteric lymphadenitis, terminal ileitis, fever, abdominal pain); severe GI bleeding possible in some cases of colitis; pharyngitis; sequelae may include erythema nodosum, reactive arthritis; sepsis, especially in elderly or immunocompromised; occasionally other syndromes, eg, septic arthritis, Far Eastern scarlet-like fever

Y enterocolitica; not all serotypes are pathogenic

Many domestic and wild mammals, including rodents; some birds, reptiles, amphibians; pigs are a major source of zoonotic organisms, pathogenic types also occur in dogs, cats

Worldwide; prevalence of human disease may vary between regions

Ingestion, as for Y pseudotuberculosis (pork is a common source), animal contact

Gastroenteritis sometimes bloody; pseudoappendicitis; sequelae may include erythema nodosum, reactive arthritis; myocarditis, other syndromes; sepsis possible

Rickettsial Diseases

Human ewingii ehrlichiosis (formerly granulocytic ehrlichiosis)

Ehrlichia ewingii

Dogs, deer proposed

Parts of North and South America, Africa; closely related organism in Asia

Ticks, including Amblyomma americanum

Few cases described; fever, headache, malaise, myalgia, nausea, vomiting (rash seems to be uncommon); probably mild in most healthy people; many patients were immunosuppressed

Ehrlichia chaffeensis

Cervids, other domestic and wild mammals

North and South America, Asia, Africa; evidence for E chaffeensis or related organism in Europe

Ticks, including Amblyomma americanum

Asymptomatic to nonspecific febrile illness; rash in many pediatric cases, some adults; may progress to prolonged fever, renal failure, respiratory distress, hemorrhages, cardiomyopathy, neurologic signs, multiorgan failure; more severe in immunosuppressed, elderly; estimated case fatality rate 1%

Human granulocytic anaplasmosis (formerly human granulocytic ehrlichiosis)

Anaplasma phagocytophilum (formerly Ehrlichia phagocytophilum and E equi)

Wild rodents, deer and other wild ungulates; production animals may be reservoirs; many other animals can also be infected


Tick bites (Ixodes spp), possibly exposure to blood or tissues from infected animals

Resembles human monocytic ehrlichiosis; often asymptomatic to mild in immunocompetent; rash uncommon; estimated case fatality rate < 1%

Infection by other Ehrlichia species

E canis, other organisms (eg, Emuris-like organism, possibly E ruminantium) implicated rarely in human illness

Dogs and other canids thought to be reservoirs; for E canis also reported in other animals including felids, camels, cattle, racoons,

E canis worldwide


Rare cases of febrile illness, in both healthy and immunosuppressed

Q fever Coxiellosis (Query fever)

Coxiella burnetii

Sheep, cattle, goats, cats, dogs, deer, rodents, small mammals, other domestic and wild mammals, birds


Mainly airborne; exposure to placenta, birth tissues, animal excreta; occasionally ingestion (including unpasteurized milk); possibly tickborne infections

Febrile influenza-like illness; atypical pneumonia, hepatitis, occasionally other syndromes; persistent, localized infection of blood vessels, heart valve or other tissues, usually in those with pre-existing damage; possible pregnancy complications; overall case fatality rate 1%–2% if untreated

Sennetsu fever

Neorickettsia sennetsu

Uncertain, possibly fish

Japan, Malaysia, Laos, possibly other Asian countries

Possibly ingestion of raw fish

Relatively mild, nonspecific, febrile illness, resembles infectious mononucleosis

Spotted fever group of Rickettsia

—African tick bite fever

R africae

Cattle, other domestic and wild ungulates

Sub-Saharan Africa, eastern Caribbean

Bite of infected tick (mainly Amblyomma spp, possibly some Rhipicephalus spp

Nonspecific febrile illness; painful regional lymphadenopathy, stiffness and pain of neck muscles common; eschars often multiple; sometimes sparse maculopapular or vesicular rash; complications rare and deaths apparently absent or very rare

—Mediterranean spotted fever; Boutonneuse fever;

Israeli spotted fever, Astrakhan spotted fever, Indian tick typhus

R conorii

Rabbits, possibly rodents, dogs implicated as reservoirs for R conoriiconorii in Mediterranean; other animals can be infected

Europe, Africa, Asia

Bite of infected ticks (mainly Rhipicephalus spp), crushing tick

Nonspecific febrile illness; eschar (typically single) may or may not be present; rash, in most; complications including neurologic signs, cardiac involvement, multiorgan dysfunction, retinitis possible but uncommon; case fatality rate 1%–3% if untreated; R conorii subsp. israelensis might be more virulent

—Fleaborne spotted fever; cat flea typhus

R felis (synonym ELB agent)

Dogs seem to be a reservoir host; evidence for organisms in cats and diverse other domestic and wild mammals


Flea bites; mainly associated with Ctenocephalides felis (cat flea), also infects C canis and other fleas; possibly other arthropods

Febrile illness; rash in some; eschar may be uncommon; most cases seem to be mild but complications including CNS involvement, pneumonia; deaths possible

—Queensland tick typhus

R australis

Bandicoots, rodents


Bite of infected Ixodes tick, especially I holocyclus, I tasmani

Febrile illness, eschar may be present, rash (either maculopapular or vesicular) in most; mild in most, but serious complications, death possible

—Rickettsial pox

R akari

Mice; also rats, Korean voles

Organism may be cosmopolitan; human cases seem to be uncommon, mainly reported in a few locations in North America, Europe

Bite of infected rodent mites, Liponyssoides sanguineus

Eschar (single) in most; febrile illness; maculopapular rash progresses to vesicular, pustular, resembles chickenpox; self-limiting

—Rickettsia parkeri rickettsiosis

R parkeri

North and South America

Bite of infected Amblyomma spp ticks

Resembles Rocky Mountain spotted fever (RMSF) but seems to be milder in most cases; and eschars common (may be multiple), petechial rash does not seem characteristic

R rickettsii

Rodents, rabbits, opossums, and other small mammals might amplify; dogs can be infected

North and South America

Bite of infected ticks; especially Dermacentor variabilis, D andersoni (in North America); Amblyomma spp, D nitens in South America; Rhipicephalus sanguineus also a vector in some areas; from crushing tick

Moderate to severe febrile illness; macular to generalized petechial rash; edema in some; usually no eschar; neurologic, pulmonary, hemorrhagic, and kidney signs in some; sepsis; gangrene; case fatality rate 15%–30% or higher if untreated, might be more severe in Brazil

—Tickborne lymphadenopathy; Dermacentor necrosis-erythema-lymphadenopathy

R slovaca, R raoultii

Uncertain; wild boar may be involved

Europe to Central Asia

Bites of infected ticks;Dermacentor marginatus, and other species

Eschar, local lymphadenopathy; localized alopecia at bite site; mild illness, fever and rash uncommon; no deaths reported

—Other tickborne species in spotted fever group

R sibirica, R japonica, R helvetica, R honei, R heilongjiangensis, R aeschlimannii, R massiliae, R monacensis; others

Various vertebrates

Distribution varies by species

Bites of ixodid ticks; specific vector varies by species

Similar to other rickettsial diseases, with inoculation site eschar, rash, febrile illness, prevalence of major clinical signs, risk of complications, severity varies

Typhus group of Rickettsia

—Murine typhus (fleaborne typhus, endemic typhus)

R typhi

Rats are major reservoir; opossums in some areas; cats, dogs, other species probably involved in peridomestic cycle

Worldwide, especially warmer regions

Infected rodent fleas, usually via flea feces; cat fleas seem to be involved in some cycles

Fever, severe headache, central rash (not always observed); other clinical signs, including arthralgia, cough, nausea/vomiting in some; complications possible in various organs; case fatality rate mortality rate < 1% without treatment

—Scrub typhus; Chigger-borne rickettsiosis

Orientia tsutsugamushi and related species

Rodents, insectivores

Asia, Australia, islands of southwestern Pacific Ocean; cases are usually concentrated regionally; related organisms may exist in Africa, Middle East, South America

Bite of infected larval trombiculid mites (chiggers)

Nonspecific febrile illness with rash, painful lymphadenopathy, GI signs; eschar in some; complications can include pulmonary disease, neurologic signs, cardiac involvement, jaundice; mild to severe, with estimated case fatality rate from 6% to 30%–50% if untreated

—Typhus, sylvatic (zoonotic cycle)

R prowazekii

Flying squirrels (Glaucomy s volans)

Eastern US (only human reservoirs known in other locations)

Squirrel lice or fleas suspected

Nonspecific febrile illness, rash; GI signs in some; sepsis possible; most cases seem to be milder than non-zoonotic typhus, which has a mortality rate of 10%–60%