Main » Infectious diseases » Arthropod-borne Infection » Plaque
Plague is now largely focal in distribution.
Known and probable foci of plague
It spreads rapidly in conditions of war and other catastrophes, eg earthquakes. Recent epidemics have occurred in Vietnam.
Photo 1. Yersinia pestis in liver smear. Y. pestis (syn. Pasteurella pestis) is a gram negative cocco-bacillus with bipolar staining. It is normally enzootic in rats. (X1250)
Plague is transmitted by fleas of the genus Xenopsylla. X. cheopis (2 & 3); X. ostia (4 & 5); X. braziliense (6 & 7). The rat flea X. cheopis is the main vector. (x60)
Photo 2. Male and female Xenopsylla fleas compared.
Photo 3. Male and female Xenopsylla fleas compared (X. cheopis).
Photo 4. Male and female Xenopsylla fleas compared (X. ostia).
Photo 5. Male and female Xenopsylla fleas compared (X. ostia) too.
Photo 6. Male and female Xenopsylla fleas compared (X. braziliense).
Photo 7. Male and female Xenopsylla fleas compared (X. braziliense) too.
Photo 8. Proventiculus of X. cheopis blocked by plaque bacilli.
Hungry fleas leave dying domestic rats (R. norvegicus, R. rattus) often with their foreguts blocked by bacilli. In this condition they will attempt to feed on any animal. If they bite man they transmit the disease. (x 120)
Photo 9. Metal guards preventing acces of along ship hawsers. Plague control demands strictly enforced rodent control measures and international quarantine regulations, particularly for shipping.
Photo 10. Bubonic plaque. One of the most characteristic clinical features is lymphadeno- pathy with suppuration especially in the inguinal and axillary regions.
Photo 11. Pneumonic plaque. Pneumonic infection allows direct spread of bacteria from man to man. The X-ray shows infection in the left lower lobe on the second day of the illness.
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