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PLAGUEORBLACK DEATH

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Plague

During the middle ages, plague was referred to as theBlack Death because of the darkened, bruisedappearance of the corpses.

The blackened skin and foul smell were the result ofcell necrosis and hemorrhaging into the skin.

Plague probably dates back a thousand or more yearsBC. In the past 2,000 years, the disease has killedmillions of people, perhaps hundreds of millions.

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Etiologic AgentYersinia Pestis; a nonmotile, bipolar-staining, Gram-

negative coccobacillus; sometimes reffered to as theplague bacillus.

Reservoirs and Mode of Transmission

Wild rodents (especialy ground squirrrels in the U.S.) andtheir fleas; rarely, rabbits, wild carnivores, and domesticcats.

Transmission is usually via Flea bite(rodent flea human).Also handling of tissues of infected rodents, rabbits, andother animals as well as droplet transmission from personto person (in pneumonic plague)

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Bubonic Plague

Is named for swollen, inflamed, and tender lymph nodes(buboes) that develop, usually lymph nodes receivingdrainage from the site of the flea bite.

In about 90% of cases, the inguinal (groin area) lymphnodes are involved.

Pneumonic Plague

Which is highly communicable, involves lungs; it can result

in localized outbreaks or devastating epidemics.

Septicemic Plague

Septic shock, meningitis, and death may occur.

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SIGNS AND SYMPTOMS

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TREATMENT

As soon as a diagnosis of suspected plague is made, the patient should

be isolated, and local and state health departments should be notified.Confirmatory laboratory work should be initiated, including bloodcultures and examination of lymph node specimens if possible. Drugtherapy should begin as soon as possible after the laboratoryspecimens are taken. The drugs of choice are streptomycin or

gentamycin, but a number of other antibiotics are also effective(please read the box below for more information about plaguetreatment).

Those individuals closely associated with the patient, particularly incases with pneumonia, should be traced, identified, and evaluated.Contacts of pneumonic plague patients should be placed underobservation or given preventive antibiotic therapy, depending on thedegree and timing of contact.

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Specific therapy

Aminoglycosides: streptomycin and gentamicin

Streptomycin is the most effective antibiotic against Y. pestisand the drugof choice for treatment of plague, particularly the pneumonic form.Therapeutic effect may be expected with 30 mg/kg/day (up to a total of 2g/day) in divided doses given intramuscularly, to be continued for a full courseof 10 days of therapy or until 3 days after the temperature has returned tonormal. Gentamicin has been found to be effective in animal studies, and isused to treat human plague patients.

Chloramphenicol

Chloramphenicol is a suitable alternative to aminoglycosides in the treatmentof bubonic or septicaemic plague and is the drug of choice for treatment ofpatients with Y. pestisinvasion of tissue spaces into which other drugs passpoorly or not at all (such as plague meningitis, pleuritis, or endophthalmitis).Dosage should be 50 mg/kg/day administered in divided doses eitherparenterally or, if tolerated, orally for 10 days. Chloramphenicol may be usedadjunctively with aminoglycosides.

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Tetracyclines

This group of antibiotics is bacteriostatic but effective in the primarytreatment of patients with uncomplicated plague. An oral loading dose of 15

mg/kg tetracycline (not to exceed 1 g total) should be followed by 25-50mg/kg/day (up to a total of 2 g/day) for 10 days. Tetracyclines may also beused adjunctively with other antibiotics.

Sulfonamides

Sulfonamides have been used extensively in plague treatment and prevention;however, some studies have shown higher mortality, increased complications,and longer duration of fever as compared with the use of streptomycin,chloramphenicol or tetracycline antibiotics. Sulfadiazine is given as a loadingdose of 2-4 g followed by a dose of 1 g every 4-6 hours for a period of 10days. In children, the oral loading dose is 75 mg/kg, followed by 150

mg/kg/day orally in six divided doses. The combination drug trimethoprim-sulfamethoxazole has been used both in treatment and prevention of plague.

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Fluoroquinolones

Fluoroquinolones, such as ciprofloxacin, have been shown to have good effectagainst Y. pestisin both in vitro and animal studies. Ciprofloxacin is

bacteriocidal and has broad spectrum activity against most Gram-negativeaerobic bacteria, including Enterobacteriaceaeand Pseudomonas aeruginosa, aswell as against many Gram-positive bacteria. Although it has been usedsuccessfully to treat humans with Francisella tularensisinfection, no studieshave been published on its use in treating human plague.

Other classes of antibiotics (penicillins, cephalosporins, macrolides)

These classes of antibiotics have been shown to be ineffective or of variableeffect in treatment of plague and they should not be used for this purpose.

Supportive therapy

The clinician must prepare for intense supportive management of plaguecomplications, utilizing the latest developments for dealing with Gram-negativesepsis. Aggressive monitoring and management of possible septic shock, multipleorgan failure, adult respiratory distresssyndrome (ARDS) and disseminatedintravascular coagulopathy should be instituted.

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Treatment of plague during pregnancy and in children

With correct and early therapy, complications of plague in pregnancy can beprevented. The choice of antibiotics during pregnancy is confounded by the

potential adverse effects of three of the most effective drugs.Streptomycin may be ototoxic and nephrotoxic to the foetus. Tetracycline hasan adverse effect on developing teeth and bones of the foetus.Chloramphenicol carries a low risk of "grey baby" syndrome or bone-marrowsuppression.Experience has shown that an aminoglycoside judiciously administered is

effective and safe for both mother and foetus, and in children.Because of its safety, intravenous or intramuscular administration, and abilityto have blood concentrations monitored, gentamicin is the preferred antibioticfor treating plague in pregnancy.

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Prophylactic therapy

Persons in close contact with pneumonic plague patients, or persons likely tohave been exposed to Y. pestis-infected fleas, to have had direct contactwith body fluids or tissues of a Y. pestis-infected mammal, or exposed duringa laboratory accident to known infectious materials should receive antibioticpreventive therapy, if the exposure was in the previous six days.

The preferred antimicrobials for preventive or abortive therapy are thetetracyclines, chloramphenicol, or one of the effective sulfonamides.

True prophylaxis, i.e. the administration of an antibiotic prior to exposure,may be indicated when persons must be present for short periods in plague-active areas under circumstances in which exposure to plague sources (fleas,

pneumonic cases) is difficult or impossible to prevent.

Vaccination: Plague vaccines are availableworldwide, but are not recommended forimmediate protection in outbreak situations.

Vaccination is only recommended for high-risk groups, e.g. health workers andlaboratory personnel who are constantlyexposed to the risk of contamination.

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DIAGNOSIS

Obsevation of typical appearance (bipolar-staining

bacilli that resemble safety pins) in Gram-stained orWright-Giemsa-Stained sputum, CSF, or materialaspirated from bubo. Culture, biochemical test,immunodiagnostic test.

NURSING INTERVENTIONEnsure dissemination of information concerning clinical features andcase definition to health workers;

Verify that patients have been placed on appropriate antibiotictreatment and that local supplies of antibiotics are adequate tohandle further cases;

Isolate pneumonic plague patients.