yersinia
Yersinia including bubonic plague and Yersiniosis
introduction
Yersinia pestis
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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
clinical presentations
bubonic plague
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
septicaemic plague
pneumonic plague
Yersinia enterocolitica
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
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)
Clinical features
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
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Diagnosis
Sequelae
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
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Mx of Y. enterocolitica infection
stool m/c/s
supportive care as most cases are self-limiting
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those with sepsis, severe ill;ness or who are immunocompromised, should be treated with antibiotics such as:
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
yersinia.txt · Last modified: 2018/08/11 13:10 (external edit)