August 02, 2016

Some Feline Respiratory Infections Can Cross Species Lines

Cats can transmit several different respiratory pathogens to humans. Recognizing these diseases can help veterinarians appropriately treat feline patients and counsel clients about preventing zoonotic transmission.

By Amy Karon, DVM, MPH, MA
Cats can transmit several different respiratory pathogens to humans. Recognizing these diseases can help veterinarians appropriately treat feline patients and counsel clients about preventing zoonotic transmission.

PLAGUE

Yersinia pestis is a gram-negative, facultative anaerobic, rod-shaped, nonspore-forming coccobacillus that causes plague.1 Cats typically are infected by contact with infected rodents or rabbits or from the bite of an infected flea.2 Bubonic plague, the most common form of plague in cats, is characterized by fever, lethargy, anorexia, and lymphadenitis in a single node or a cluster of nodes.2

Cats with primary systemic plague do not present with focal lymphadenitis, but typically develop tachycardia, diarrhea, vomiting, and respiratory distress syndrome.2 They can also develop secondary pneumonic plague, which tends to cause diffuse necrotizing interstitial pneumonia.2 Thoracic radiography reveals destruction of the lung architecture and, in some cases, pulmonary abscess.2,3

Secondary pneumonic plague in cats is a serious public health risk because of the potential for respiratory droplet transmission to humans.2 There has been at least one case of a human who died from primary pneumonic plague acquired from contact with an infected cat.4

Cats can also bring fleas infected with Yersinia pestis into the home or a shelter, where they can bite humans and other animals. Cats with suspected Yersinia pestis infection should be hospitalized, especially if they show signs and symptoms of pneumonia.2 Cats should be isolated for at least 48 to 72 hours after beginning appropriate antibiotic therapy and until they improve clinically.2
 

TULAREMIA

Francisella tularensis is a highly infectious, gram-negative coccobacillus transmitted by a dog tick (Dermacentor variabilis), wood tick (Dermacentor andersoni), lone star tick (Amblyomma americanum) and, in the western United States, deer flies (Chrysops species).5 Cats are highly susceptible to infection by these routes or by consuming infected tissue.5,6 They may be asymptomatic or present with acute fever, lymphadenopathy, anorexia, dehydration, draining abscess, oral or lingual ulcers, pneumonia, hepatomegaly, and splenomegaly.6
 
Cats can readily transmit tularemia to humans, most often through bites or scratches, but also through droplet transmission or exposure to secretions.5 Asymptomatic infected cats can also infect humans.5 Veterinarians should consider tularemia in cats with acute febrile illness, especially if they hunt wild prey.6
 
Among humans, the case-fatality rate for untreated tularemia is up to 30%.7 To prevent zoonotic transmission, cats with tularemia should be isolated and cases should be reported to the local public health department.7
 

LUNGWORM

Lungworm in cats includes infections with Aelurostrongylus abstrusus, Oslerus rostratus, Troglostrongylus species, Capillaria aerophila, and several Paragonimus species.8 Infections can be asymptomatic or may cause mild to severe respiratory disease, presenting as productive cough, mucopurulent nasal discharge, dyspnea, tachypnea, pleural effusion, pneumothorax, and respiratory failure.8
 
A. abstrusus, the most common lungworm among domestic cats, is host-specific.8 However, C. aerophila often infects cats and can be transmitted to humans and dogs through contact with feces containing embryonated eggs.8,9 Paragonimus are also zoonotic, but humans are only infected by consuming raw or undercooked crabs or crayfish, the second intermediate host.8
 
Veterinarians should consider lungworm in outdoor cats, especially if they present with pulmonary hypertension and right-sided heart failure.8 In general, the best way to prevent lungworm infections is to keep cats from preying on hosts and counsel clients regarding fecal-oral transmission.8,9 In humans, capillariasis causes productive cough, bronchitis, hemoptysis, fever, dyspnea, and pulmonary lesions.10
 


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