The importance of disease transmission between humans and animals was recently reaffirmed by CDC’s report title “Outbreak of Human Pneumonic Plague with Dog-to-Human and Possible Human to-Human Transmission — Colorado, June–July 2014, published in the MMWR on May 1, 2015.

“Normally a pathogen of rodents, [plague] Y. pestis is transmitted to humans through the bite of infected rodent fleas or direct contact with the tissues or secretions of infected animals.”

In this case, the disease was first transmitted from a dog to his owner.

Three other persons who had contact with the dog, one of whom also had contact with the owner were ill with fever and respiratory symptoms, including two with radiographic evidence of pneumonia. Specimens from the dog and all three human contacts yielded evidence of acute Y. pestis infection.

The MMWR reported that

this outbreak highlights 1) the need to consider plague in the differential diagnosis of ill domestic animals, including dogs, in areas where plague is endemic; 2) the limitations of automated diagnostic systems for identifying rare bacteria such as Y. pestis; and 3) the potential for milder plague illness in patients taking antimicrobial agents.

This outbreak is further evidence of the importance of the close relationship between human and animals, and the potential for the spread of infectious, highly contagious diseases between species.

 Y. pestis infection in dogs generally is either asymptomatic or the cause of only a mild, self-limiting febrile illness . Dogs can play a role in human infection through transport of rodent fleas into the home. This outbreak began with illness in a pet dog, a previously unrecognized source of plague exposure in the United States. The only previously published case of direct transmission of plague from a dog to a human was reported from China in 2009. Although symptomatic plague in dogs is rare, veterinarians should consider the possibility of Y. pestis infection in ill dogs with wildlife exposure in areas where plague is endemic.

Plague is not the only disease humans and animals share and can transmit to each other.

CDC lists the following diseases that can be transmitted from animals to humans:

  • Aeromonas Infection
  • Ancylostoma braziliense Infection – see Hookworm Infection
  • Ancylostoma caninum Infection (Hookworm Infection)
  • Avian Influenza
  • Bartonella henselae Infection
  • Baylisascaris procyonis Infection (Raccoon Roundworm Infection)
  • B Virus Infection (Herpes B Virus Infection)
  • Bird Flu – see Avian Influenza
  • Black Death – see Plague
  • Bovine Spongiform Encephalopathy (Mad Cow Disease)
  • Brucella Infection (Brucellosis)
  • Brucellosis (Brucella Infection)
  • BSE – see Mad Cow Disease
  • Bubonic Plague – see Plague
  • C. neoformans Cryptococcosis
  • Campylobacter Infection (Campylobacteriosis)
  • Campylobacteriosis (Campylobacter Infection)
  • Canine Influenza
  • Cat Scratch Disease
  • Cave Disease – see Histoplasmosis
  • Chlamydia psittaci Infection (Psittacosis)
  • Contagious Ecythema – see Sore Mouth
  • Contagious Pustular Dermatitis – see Sore Mouth
  • Coxiella burnetti Infection (Q fever)
  • Cryptococcosis, C. neoformans
  • Cryptosporidiosis (Cryptosporidium Infection)
  • Cryptosporidium Infection (Cryptosporidiosis)
  • CSD – see Cat Scratch Disease
  • Cysticercosis (Pork Tapeworm)
  • Dermatophyte Infection (Ringworm)
  • Dipylidium Infection (Tapeworm Infection)
  • Dog flu – see Canine Influenza
  • Echinococcosis (Echinocococcus Infection)
  • Echinocococcus Infection (Echinocococcus Infection)
  • E. Coli Infection (Escherichia coli O157:H7 infection)
  • Erysipelothrix Infection
  • Escherichia coli O157:H7 Infection (E. coli Infection)
  • Fish Tank Granuloma (Mycobacterium marinum Infection)[PDF – 4 pages]
  • Francisella tularensis Infection (Tularemia)
  • Giardiasis (Giardia Infection)
  • Giardia Infection (Giardiasis)
  • H3N8 Influenza – see Canine Influenza
  • Hantavirus Pulmonary Syndrome (HPS)
  • Herpes B Virus Infection (B Virus Infection)
  • Herpesvirus simiae Infection – see B Virus Infection
  • Histoplasma Infection – see Histoplasmosis
  • Histoplasmosis (Histoplasma Infection)
  • Hookworm Infection (Ancylostoma caninum Infection)
  • HPS (Hantavirus Pulmonary Syndrome)
  • LCMV (Lymphocytic Choriomeningitis)
  • Leishmania Infection (Leishmaniasis)
  • Leishmaniasis (Leishmania Infection)
  • Leptospira Infection (Leptospirosis)
  • Leptospirosis (Leptospira Infection)
  • Lyme Disease (Borrelia burgdorferi Infection)
  • Lymphocytic Choriomeningitis (LCMV) ◦Lymphocytic Choriomeningitis Virus from Pet Rodents
  • Mad Cow Disease – see Bovine Spongiform Encephalopathy
  • Methicillin-Resistant Staphylococcus aureus Infection (MRSA)
  • Microsporum Infection – see Ringworm
  • Monkey B Virus Infection – see B Virus Infection
  • Monkeypox
  • MRSA (Methicillin-Resistant Staphylococcus aureus Infection)
  • Mycobacterium marinum Infection (Fish Tank Granuloma)[PDF – 4 pages]
  • Mycobacterium tuberculosis Infection (Tuberculosis)
  • Ohio Valley Disease – see Histoplasmosis
  • Orf Virus Infection (Sore Mouth)
  • Plague (Yersinia pestis Infection)
  • Psittacosis (Chlamydia psittaci Infection)
  • Q Fever (Coxiella burnetti Infection)
  • Rabies
  • Raccoon Roundworm Infection (Baylisascaris procyonis Infection)
  • Rat-bite Fever (Streptobacillus moniliformis Infection, Spirillum minus Infection)
  • RBF – see Rat-bite Fever
  • Rickettsia rickettsia Infection (Rocky Mountain Spotted Fever)
  • Ringworm (Dermatophyte Infection)
  • RMSF – see Rocky Mountain Spotted Fever
  • Rocky Mountain Spotted Fever (Rickettsia rickettsia Infection)
  • Roundworm Infection (Toxocariasis)
  • Salmonella Infection (Salmonellosis)
  • Turtles Kept as Pets
  • Salmonella from Pocket Pets
  • Salmonellosis (Salmonella Infection)
  • Sarcoptes scabeii Infection (Sarcoptic Mange)
  • Sarcoptic Mange (Sarcoptes scabeii Infection)
  • Scabby Mouth – see Sore Mouth
  • Sore Mouth (Orf Virus Infection)
  • Spirillum minus Infection (Rat-bite Fever)
  • Sporothrix schenckii Infection (Sporotrichosis)
  • Sporotrichosis (Sporothrix schenckii Infection)
  • Streptobacillus moniliformis Infection (Rat-bite Fever)
  • Taenia solium Infection – see Cysticercosis
  • TB – see Tuberculosis
  • Taeniasis – see Cysticercosis
  • Tapeworm Infection (Diplyidium Infection)
  • Tinea – see Ringworm
  • Toxocara Infection – see Roundworm
  • Toxocariasis (Roundworm Infection)
  • Toxoplasma gondii Infection (Toxoplasmosis)
  • Toxoplasmosis (Toxoplasma gondii Infection)
  • Trychophyton mentagrophytes Infection – see Ringworm
  • Tuberculosis (Mycobacterium tuberculosis Infection)
  • Tularemia (Francisella tularensis Infection)
  • Uncinaria stenocephala Infection – see Hookworm Infection
  • West Nile Virus Infection
  • Yersinia enterocolitica Infection (Yersiniosis)
  • Yersinia pestis Infection – see Plague
  • Yersiniosis (Yersinia enterocolitica Infection)

Medical professionals in veterinary and human medicine should be familiar with these diseases and their zoonotic poential in order to protect their patients, no matter the species.