clinical features epidemiology lab diagnosis prophylaxis treatment k.vanya

CLINICAL FEATURESEPIDEMIOLOGYLAB DIAGNOSISPROPHYLAXISTREATMENT

k.vanya

Clinical features

Clinical features of B.anthracis:Anthrax is a zoonotic disease.Anthrax “coal” ,comes from black

colour of escharRoute of infection: ingestion / inhalation of

spores /it may enter directly through skin.Infective material: discharges from mouth ,

nose &rectum of infected animals.The large no. of bacilli present in those

discharges sporulate in soil and remain as source of infection.

Direct spread from animal to animal is rare.

it causes fatal septicemia, but some times it is localized/resemble cutaneous diseases in humans.

acquired from animals directly / indirectly.Based on clinical features, Anthrax is divided into 3 types

cutaneous pulmonary intestinal All these lead to fatal septicemia/meningitis

Cutaneous anthraxAlso called “hide porter’s disease”, as it is

common in dock workers,Route of infection: infection enter through

abraded skin.◦Also by shaving brushes made of animal hair

Usual sites: face,neck,hands,arms&back Lesion starts as papule 1-3 days after

infection

becomes vesicular (fluid clear/blood stained)

Malignant pustule:The whole area congested,

edematous & several satellite lesions filled with yellow fluid/serum arranged around central necrotic lesion which is covered by black eschar.

resolves spontaneously.Complications: 10-20% develop fatal

septicemia/meningitis

Malignant pustuleCongested

Edematous

Satellite lesions

Pulmonary anthraxAlso called “wool sorter’s disease”.Because it is common in wool

factories.Route of infection: due to inhalation

of dust from infected wool.More severe than others.Complications:

hemorrhagic pneumonia (common) hemorrhagic meningitis(rare)

Intestinal anthraxRareMainly in primitive communities

i.e. who eat dead bodies of animals died of anthrax.

Complication: violent enteritis with bloody

diarrhea with high fatality rate

industrial Based on occupation non-industrial

Industrial: such as meat packing/wool factories.

Non-industrial: associated with animals(butchers

&farmers)

Rarely stomoxys calcitrans –biting insect transmit infection mechanically.

Epidemiology:Rare in western countriesLarge epidemics

russia&zimbabwe(1978-80)

Recently visakha agency has outbreaks of cutaneous anthrax

Andhra –tamilnadu region

Cutaneous,meningoencephalitic infections

Laboratory diagnosis

1)microscopy 2)culture

3)Animal inoculation 4)Serological

demonstration of anthrax Ag in

tissueType of test

based on availability

of specimens

Specimens: swab, fluid/pus from pustule-cutaneous anthrax

Sputum-pulmonary anthrax.Blood-septicemia anthrax.

Microscopy:Gram positive bacilli arranged in

large chains.

Capsule --Clear halo around bacillus in Indian ink preparation

Direct flourescent antibody test: capsule specific staining for poly saccharide Ag

Mc fadyean’s reaction :Amorphous purple material – characteristic of B.anthracis.

Employed for presumptive diagnosis in animals

Mc fadyean’s reaction

Culture : inoculated on nutrient agar incubate at 37 c for overnight.

-medusa head coloniesGelatin stab culture : inverted fir

tree

Animal inoculation : white mouse / guinea pigs injected with exudate /culture

Animal dies in 48 hrs

Serology ( Ascoli Thermo Precipitin Test ):

Tissues are ground up in saline and boiled for 5

mins and filtered. Then this extract layered over

anti anthrax serum in a narrow tube.

+ve case :ring of precipitate appears at junction of two liquids with in 5minutes.

mainly used for rapid diagnosis

when sample received is putrid and viable bacilli less likely found

CDC(centers for disease control)guide lines:

Any large gram positive baciili with general morphology, cultural features of anthrax-non motile, on hemolytic on blood agar,catalase positive given presumptive report as anthrax.

Initial confirmation-lysis by gamma phage,DFA test.

Further confirmation:PCR test

Other methods :Polymerase chain reaction : used

for conformation of anthrax bacilli.

ELISA assay for antigen detectionX-ray and CT scanLysis by gamma phage

PROPHYLAXIS:General methods : improvement of factory hygiene proper sterilization of animal

products , carcasses of animals suspected to have anthrax are buried deep in lime.

Active immunizationSpore is common infective formSterne vaccine contains spores of

non capsulated avirulent mutant strain

Animal is protected for a year with single injection of spore vaccine

Extensively used in animalsNot safe for human use

Contd….Alum precipitated toxoid

prepared from protective antigens used in persons occupationally exposed to anthrax infection.

Safe and effective in humansGiven in 3 doses IM at intervals

of 6 weeks

Treatment:Before 2001, 1st line of treatment

was penicillin G◦ Stopped for fear of genetically

engineered resistant strains60 day course of antibioticsCiprofloxacin

◦ fluoroquinolone◦ 500 mg tablet every 12h or 400 mg

IV every 12h ◦ Inhibits DNA synthesis

Doxycycline◦ 6-deoxy-tetracycline◦ 100 mg tablet every 12h or 100 mg

IV every 12h ◦ Inhibits protein synthesis

For inhalational, need another antimicrobial agent◦ clindamycin ◦ rifampin ◦ chloramphenicol

Anthrax infection gives permanent immunity&2nd attacks are rare.

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