Is An Infection Indigenous To Animals That Can, On Occasion, Be Transmitted To Humans.
There are some leaner that spend most of their time in animal hosts, only occasionally infect humans who have close contact with animals. These zoonotic infections include brucellosis (acquired past slaughtering or drinking the milk of cows, sheep or camels infected with Brucella) and cat-scratch disease (acquired by Bartonella henselae and caused by—well, you can probably estimate). In other cases, however, 2 (or more) related species or genera of leaner have adapted to live, and sometimes crusade illness, in unlike hosts, with 1 species sticking to an animal host and another hanging out with (or in) humans.
Whooping Cough and Kennel Cough: Bordetella pertussis and Bordetella bronchiseptica
Imagine you're a physician seeing a 3-calendar month-one-time patient who has come to clinic considering of paroxysmal cough (cough that occurs in intense, prolonged bouts followed by a deep, gasping inhalation). The patient does not look acutely ill, but is coughing persistently during the exam. You're concerned about a highly contagious, gram-negative coccobacillus that may exist the source of these symptoms, because it frequently causes particularly severe illness during the kickoff months of life. What organism are you thinking about?
The respond depends on what species of patient you imagined! In humans, whooping coughing is caused by infection with Bordetella pertussis and presents with a persistent, often paroxysmal cough with a characteristic "whoop" sound during inhalation. In infants nether 4 months of historic period, pertussis can accept astringent complications, such as apnea (a temporary pause in breathing) and seizures. In dogs, a different Bordetella species, B. bronchiseptica, is one of the causes of kennel coughing, which is recognized by a characteristic cough often described every bit "honking." (Kennel cough can also be caused past viruses, including canine distemper virus, canine adenovirus type 2 and canine parainfluenza.) B. bronchiseptica can also cause upper respiratory tract infection in other mammals, including rabbits, pigs and cats, whereas B. pertussis is strictly a human pathogen and appears to accept derived every bit recently as a few thousand years ago from a B. bronchiseptica-like antecedent, with many genes lost or inactivated in the process of evolving into a pathogen with a more than limited host range.
These 2 Bordetella species have a diversity of virulence factors in common, including the adhesin filamentous hemagglutinin. Other virulence factors, such as the aptly named tracheal colonization factor and the exotoxin pertussis toxin, are expressed by only one of the organisms (B. pertussis in this instance). B. bronchiseptica expresses a flagellum that confers movement; recent work suggests that B. pertussis, although previously idea to be nonmotile, is also capable of expressing a flagellum, although the significance of this power in infection remains unclear.
Source: Adapted from CDC Public Health Paradigm Library.
Vaccination is a key chemical element in protection confronting both whooping and honking: B. pertussis vaccine is included in the routine childhood vaccination schedule in the United States (although amnesty wanes over time, and rates of pertussis take been increasing in recent years in spite of widespread vaccination in childhood), and vaccination against B. bronchiseptica is generally recommended for dogs who will be spending time in congregate settings (kennels, doggie daycare, etc.).
Infected Bites and Shipping Fever: Pasteurella multocida and Mannheimia haemolytica & Histophilus somni
Pasteurella multocida is a gram-negative rod with an extraordinarily wide range of animal hosts, including birds (fowl cholera), pigs (atrophic rhinitis), cattle (pneumonia or bovine respiratory disease) and fifty-fifty saiga antelopes. As a commensal organism plant in the mouths of domestic cats and dogs, information technology is a well-known cause of infected brute bites in humans. Thorough cleaning of all creature bites, equally well as antibiotic prophylaxis in some scenarios, can help to forbid wound infection later on a bite.
Different P. multocida, 2 other members of the family unit Pasteurellaceae, Mannheimia haemolytica and Histophilus somni, are non typically encountered as pathogens in humans. However, forth with P. multocida, they found the 3 major bacterial causes of bovine respiratory illness (BRD). Also known as "shipping fever" considering information technology commonly affects calves that accept recently arrived at the feedlot after weaning, BRD describes a syndrome of upper and lower respiratory tract infections in cattle that is believed to result from viral respiratory infection complicated by bacterial infection, frequently in the setting of underlying physiologic stresses (e.k., weaning and transport). Prevention and control of BRD is challenging. Vaccines are available for cattle against P. multocida, G. haemolytica and H. somni, every bit well many of the viruses implicated in BRD. Nonetheless, vaccination appears to have piddling consequence on reducing rates of BRD, perhaps due to poor response to vaccination by calves undergoing the stresses of weaning and shipping. In contrast, control of stressors (eastward.g. past weaning prior to shipping) and metaphylaxis (administration of antimicrobials to animals in a group after disease has been diagnosed in some members of the group, in lodge to command spread of infection) appear to be more effective.
Humans, Pigs, Cows and…Gray Seals?: Streptococci of All Kinds
Infectious disease doctors and clinical microbiologists who confine themselves to human patients are familiar with a long list of streptococci. This genus of gram-positive cocci tin be classified (somewhat confusingly) by a diverseness of unlike organizational schemes, including the pattern of hemolysis they exhibit when grown on claret agar plates (alpha (partial), beta (consummate) or gamma (none)) and the sugar antigens in their cell wall (Lancefield groups A, B, C, etc.). Streptococcal species cause an enormous range of clinical diseases, including pharyngitis ("strep throat"), cellulitis, meningitis, bacteremia, endocarditis and toxic shock syndrome. While some of these syndromes are most often caused by a specific species (pharyngitis and toxic daze syndrome by Southward. pyogenes, meningitis and pneumonia past S. pneumoniae), nearly all streptococci are capable of causing a wide spectrum of clinical manifestations.
When it comes to mastering the list of clinically relevant streptococci, veterinarians have it no easier. Streptococcal species that cause illness in animals are classified by the same systems used for "homo" species (hemolysis and Lancefield typing). Although nearly of these species can infect a diversity of hosts, their names often indicate the animal in which they most frequently crusade disease: dogs (S. canis), horses (S. equi subsp. zooepidemicus), pigs (S. suis), grayness seals (Southward. halichoeri) and dolphins and fish (S. iniae). Not all streptococci confine themselves exclusively to humans or animals. Southward. agalactiae (grouping B strep) is a major cause of invasive disease, including bacteremia and meningitis in homo newborns, too as mastitis in dairy cows. (Its species proper noun, "agalactiae," meaning "absence of milk," appears to exist a reference to its effects on milk production in infected cows.)
Source: Adapted from https://commons.wikimedia.org/wiki/File:Streptococcus_phylogeny.png.
Even among species more classically described in animals, human being infection has been described for nearly all streptococci. Zoonotic streptococci usually make the leap to humans when a person is profoundly immunosuppressed and therefore vulnerable to infection past an organism that is not otherwise suited for invasion of a human host. Furthermore, animal pathogens besides play a critical indirect role in human disease, because antibiotics used to care for domesticated animals may contribute to the emergence and spread of antimicrobial resistance among human pathogens also. In the end, information technology'due south all-time to retrieve that leaner have big animals (including humans) hopelessly beat at the game of adaptation, and the border between animal and man pathogen is never entirely impermeable.
Source: https://asm.org/Articles/2021/May/Infections-in-Animals-and-Humans-Caused-by-Bacteri
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