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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