see also:

• clinically important bacteria
• A historians' view of the bubonic plague

• Yersinia are Gram-negative, rod-shaped coccobacillus, a facultative anaerobic bacteria belonging to the enterobacteriaceae family
• Y. pestis is the organism causing the bubonic plague or Black Death epidemic and thousands of cases each year still occur

• see wikipedia
• discovered by Alexandre Yersin in 1894 during an epidemic of the plague in Hong Kong
• most of the spreading occurs between rodents and fleas (the vector) but can be spread person-to-person if in pneumonic form
• 30% of human cases worldwide are now in Madagascar which usually sees ~400 new cases per year after Indian steamships brought the plague there in 1898, and is primarily associated with rural areas and agricultural activity, where maximum abundance of rodents in the fields is observed in July and August, followed by the maximum abundance of fleas from September to November

• 2-6 days incubation
• sudden onset of headache, fever, chills
• extreme weakness, lymphadenopathy (esp. inguinal as most flea bites are on legs) which then form buboes
• death can occur in less than 2 weeks

• gastro-like illness then septicaemic shock, hepatosplenomegaly
• may not have buboes

• pneumonia-like illness
• haemoptysis
• septic shock
• person-to-person spread
• 100% mortality if untreated

• yersiniosis is an uncommon bowel infection which usually causes inflammation around the terminal ileum region causing a terminal ileitis, mesenteric lymphadenopathy or an enterocolitis
• spread to humans by eating food or drinking water contaminated by human or animal faeces, but may also result from contact with infected pets or farm animals
  • avoid drinking unpastuerised milk and maintain good hand hygiene
  • cook meat well, especially pork
• it can also be spread in blood transfusions as it can multiple in stored blood products (Yersinia are iron-loving siderophilic bacteria) - hence people should not donate blood if they have had recent diarrhoeal illness.
• incubation period is 4-7 days after exposure
• usually produce a beta-lactamase and thus are resistant to penicillins and cephalosporins (but ceftriaxone can be used)

• more common in young children
• patients with haemochromatosis are said to be more susceptible to infection
• fever
• diarrhoea which may be bloody esp. in young children
• abdominal pain and cramps
• can mimic appendicitis, Salmonella or shigella

• stool m/c/s or PCR sample

• most cases are self-limiting
• in immunosuppressed patients, it can spread to form abscesses in liver or spleen
• 50% of adults develop joint pains, some as a immune mediated reactive arthritis
• some may develop erythema nodosum
• seems to be associated with autoimmune Graves-Basedow thyroiditis although may not be causal

• stool m/c/s
• supportive care as most cases are self-limiting
• contact precautions as for gastroenteritis
• those with sepsis, severe ill;ness or who are immunocompromised, should be treated with antibiotics such as:
  • doxycycline, plus
  • gentamicin
• exclude infected cases from:
  • childcare, school, work, swimming pools until there has been no diarrhoea for 24hrs
  • however, person may remain infective to others for 2-3 weeks, and, if not treated with antibiotics, may shed in faeces for up to 2-3 months