133. Yersinioses: rodentiosis and diseases caused by Yersinia enterocolitica (Zoon.).

Question 1

What are the Pathogenic yersinia species?

Answer 1

PATHOGENIC YERSINIA SPECIES ʹ

1. Y. pestis,
2. Y. pseudotuberculosis,
3. Y. enterocolitica,
4. Y. ruckeri

Question 2

Plague ethiology epidemiology pathogenesis treatment and prevention?

Answer 2

PLAGUE

ETIOLOGY & EPIDEMIOLOGY

• Y. pestis, relationship with Y. pseudotuberculosis
• Focal infection: maintained by sylvatic cycle: wild living rodents (USA, South America, Africa, Asia)
• Urban cycle: maintained by rats
• Vector : flea (true vector: replication), (tick, louse)
• Susceptible: cats & dogs (can bring infection close to humans), rabbits and humans

PATHOGENESIS

• Infection via arthropods, inhalation (humans), wounds
• Clinical forms:
• Bubonic plague: Lymph nodes are enlargedʹ 75% lethality can be treated
• Septicemia
• Pneumonic plague ʹ 90% lethality, human-human spread via cough
• Asymptomatic infection

TREATMENT AND PREVENTION

• Antibiotics - Streptomycin and gentamicin,
• Avoid infection,
• inactivated vaccine

Question 3

Diseases caused by Y. pseudotuberculosis Occurence ethiology and epidemiology?

Answer 3

DISEASES CAUSED BY Y. PSEUDOTUBERCULOSIS ʹ PSEUDOTUBERCULOSIS, RODENTIOSIS

OCCURRENCE, ETIOLOGY AND EPIDEMIOLOGY

• Worldwide occurrence, sporadic
• Y. pseudotuberculosis, present in gut, soil, water, food propagates at 2-43°C
• Virulence factors: surface proteins responsible for adherence and intracellular survival
• Medium resistance, can survive in the environment (low resistance against heat or disinfectants)
• Wide host range: small rodents, hare, birds and mammals
• Infection P.O. (fecal contamination) or rarely via wounds or arthropods (ticks)
• Focal infection, facultative pathogenic
• predisposing factors:
• Wild living animals : starvation and cold
• Farm animals : overcrowding, parasitosis, nutrition

Question 4

Pathogenesis and clinical signs of Y.pseudotuberculosis?

Answer 4

PATHOGENESIS AND CLINICAL SIGNS

• Infection P.O.
• gut, if predisposing factors it will replicate and cause enteritis, necrosis and hemorrhages
• From the gut the bacterium can get to the mesenterial lymph nodes and to the blood
• septicemia
• focal inflammation and necrosis in liver,
• parenchymal organs (result in typical post mortem lesions)

Clinical signs:

• Acute (rare, sometimes in rodents) ʹ fever, general signs, depression, anorexia, listlessness
• Subacute, chronic
• Rodents, hare and swine ʹ diarrhea, weight loss, weakness
• Cattle: diarrhea, mastitis, sporadic abortion
• Horse: dog and cat ʹ diarrhea, anorexia, depression
• Birds: diarrhea, arthritis

Question 5

Pathology of Y.pseudotuberculosis?

Answer 5

Pathology

• Acute:
• hemorrhages,
• enlargement of the parenchymal organs and lymph nodes
• Subacute/Chronic:
• Enteritis (large intestine: hemorrhage, necrotic inflammation),
• focal inflammation & necrosis in parenchymal organs (liver, spleen, lymph nodes)
• Abortion ʹ
• fetus: focal inflammation and necrosis;
• fetal membranes: fibrinous-necrotic inflammation

Question 6

Diagnosis, treatment and prevention of Y.pseudotuberculosis?

Answer 6

DIAGNOSIS

• Epidemiology, clinical signs and pathology, Bacteriological examination ʹ isolation from parenchymal organs
• Differentiation
• Calf & lamb : agents causing diarrhea: E. coli, salmonellosis, rotavirus, coronavirus, C. perfringens
• Sheep:Lesions in lymph nodes can be mistaken for lesions caused by C. pseudotuberculosis
• Rodents: Tularemia, Brucellosis, Paratyphus
• Birds: Salmonellosis, Fowl cholera, Campylobacter hepatitis (focal infl. And necrosis in the liver)
• TREATMENT AND PREVENTION
• Antibiotics: streptomycin, tetracyclines, quinolones ʹ Whole group must be treated, remain carriers
• Prevention: hygiene, supporting resistance, rodent control, No vaccine!

Question 7

Occurence, ethiology and epidemiology of Y.enterocolitica?

Answer 7

DISEASES CAUSED BY Y. ENTEROCOLITICA

OCCURRENCE

• Widespread carriage, more frequent than Y. pseudotuberculosis, but frequently asymptomatic

Ethiology

• Y. enterocolitica normally present in gut. 34 serotypes: O9
• high level of cross reaction with Brucella
• Shed in feces by swine (responsible for maintaining infection), rodents, hare, farm animals and birds
• Contaminated water and food, frequently asymptomatic carriers, clinical signs in young animals

Question 8

Pathogenesis and clinical signs,pathology of Y.enterocolitica?

Answer 8

PATHOGENESIS AND CLINICAL SIGNS

• Infection P.O.
• present in tonsils & gut,
• if predisposing factors:
• replication in lymphoid patches and will reach
• the mesenterial lymph nodes
• septicemia
• parenchymal organs: focal inflammation and necrosis

Clinical signs

• Chinchilla and hare: fever and generalized signs (anorexia, depression)
• Swine ʹ fever, diarrhea, if recover
• withdrawn into joints: arthritis
• Ruminants ʹ sporadic abortion

Pathology

• enteritis (fibrinous and necrotic),
• focal inflammation and necrosis in gut wall,
• lymph nodes and parenchymal organs

Question 9

Diagnosis of Y. enterocolitica?

Answer 9

DIAGNOSIS

• Epidemiology, clinical signs and pathology
• Diagnosis of the disease ʹ isolation of agent from parenchymal organs
• Diagnosis of the infection
• Isolation of bacterium from faeces
• Detection of antibodies ʹ ELISA, agglutination
• Differentials
• T. pyogenes (cause microabscesses),
• Y. pseudotuberculosis,
• tularemia,
• Brucellosis

Question 10

Treatment and prevention, Public health significance of Y.enterocolitica?

Answer 10

TREATMENT AND PREVENTION

• Broad spectrum antibiotics
• Hygienic measures, rodent control, No vaccine

PUBLIC HEALTH SIGNIFICANCE

• Y. pseudotuberculosis and Y. enterocolitica ʹ wide host spectrum, including humans
• Human cases reported from all over the world
• Zoonosis
• Infection P.O. from animal, food or vegetables, water and environment
• Slaughtered meat and dairy products can be contaminated with feces
• More frequent in children (more susceptible, like to eat vegetables and fruits without washing)
• Replication in the gut and sometimes get into blood
• septicemia
• Clinical signs “appendicitis”-like clinical signs: Fever, abdominal pain (right side), diarrhea (with blood)
• Diagnosis ʹ detection of agent from feces, or detection of antibodies
• Treatment ʹ wide spectrum antibiotics, prevention ʹ avoiding infection