ANTHRAX

ANHRAX - INTRODUCTION

• Acute infectious disease - Bacillus anthracis, a gram-positive spore-forming bacillus.

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• Spores of B.anthracis - persist in the environment for many years in soil

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• Enter the body through skin abrasions, inhalation or ingestion and multiply to produce exotoxins.

Occurrence of disease

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• Anthrax - a disease of herbivorous animals that occasionally affects human
• Herbivores such as sheep, cows, horses, goats
• Natural reservoir is soil

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• Anthrax zones
• Soil rich in organic matter
• Dramatic changes in climate

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Anthrax - synonyms

• Malignant Pustule
• Malignant edema
• Wool sorter’s disease
• Rag picker's disease

GEOGRAPHICAL DISTRIBUTION�

• Anthrax is known to occur globally, it is more often a risk in countries with less standardized and less effective public health programs.

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• Anthrax is most common in agricultural regions where it occurs in animals.

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• These include South and Central America, Southern, Eastern Europe, Asia, Africa, the Caribbean, and the Middle East.

Outbreaks in Thailand

• This picture is 9 days after the onset of symptoms of oral-pharyngeal anthrax.

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• 1982 - Outbreak of 52 cases of cutaneous anthrax and 24 cases of oral-pharyngeal anthrax occurred.

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• Oral-pharyngeal anthrax: an unusual manifestation of human�infection with B. anthracis.

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• 1987 - 14 cases of both oral- pharyngeal and abdominal anthrax occurred.

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• Caused by the consumption of contaminated water and buffalo meat.

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Indian scenario

• India is enzootic for animal & endemic for human anthrax.

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• Anthrax is enzootic in southern India but is less frequent to absent in the northern Indian states.

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• Sporadic cases have been reported from different regions of India since 1953.

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CURRENT INDIAN SCENARIO�

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• In the past years the anthrax cases have been reported from Andhra Pradesh, Jammu and Kashmir, Tamil Nadu, Orissa and Karnataka.

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• Outbreaks of Anthrax have been reported from Mysore 1999, Orissa 2004, 2005, West Bengal 2000.

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7 Cutaneous Anthrax

Lamtaput

6 Cutaneous Anthrax

1 Abdominal Anthrax

 1

 1

• 5

• 5

• 7

• 16

• 84

• 19

• 32

• 2

• 9

• 15

• 9

• 3

• 23

Human (1977-2005 till date) and Animal (1992-2002)Cases in Vellore District

Human anthrax-Indian experience

Number

of

cases

Anthrax in Vellore region

• First case encountered in Vellore region-1977.

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• Case of anthrax meningo encephalitis seen in a 35 year old male during 2^nd March 2005.

Outbreaks in the US

• In the early 1900’s approximately 130 cases occurred annually due to the following reasons.

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1) Agricultural, farm workers exposed to infected animals

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2) Processors exposed to infected animal products (hair,

leather, wool, bone)

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3) Laboratory workers contacted with anthrax spores

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4) Civilians exposed to contaminated imported animal products

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• These four are rare today.

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SEASONAL DISEASE

• Anthrax is a seasonal disease.

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• Climate acts directly or indirectly by influencing the way in which the animal comes into contact with the spores, for example, grazing closer to the soil in dry periods when grass is short and sparse

Exposure to disease

• People who work directly with it in the lab

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• People who work with imported animal hides or furs in areas where standards are insufficient to prevent exposure to anthrax spores.

• People who handle potentially infected animal products in high-incidence areas

CLINICAL MANIFESTATIONS

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1. Cutaneous anthrax

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• Pulmonary anthrax

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• Gastro-intestinal anthrax

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*Fatal septicemia and meningitis are reported

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Endospore

• Oxygen required for sporulation
• Highly resistant to heat, cold, chemical disinfectants, dry periods
• Cortex provides heat and radiation resistance
• Spore wall provides protection from chemicals & enzymes

Toxins

• pX01 plasmid

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• Protective antigen (PA)
• Edema factor (EF)
• Lethal factor (LF)

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• Individually non-toxic
• PA+LF 🡪 lethal activity
• EF+PA 🡪 edema
• PA+LF+EF 🡪 edema & necrosis; lethal

Three forms of Anthrax

• Cutaneous anthrax
• Skin
• Most common
• Spores enter to skin through small lesions

• Inhalation anthrax
• Spores are inhaled

• Gastrointestinal (GI) anthrax
• Spores are ingested
• Oral-pharyngeal and abdominal

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Cutaneous Anthrax

• The most common naturally occurring form of anthrax.

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• Ulcers are usually 1-3 cm in diameter.

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• Incubation period:
• Usually an immediate response up to 1 day

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• Case fatality after 2 days of infection:
• Untreated (20%)
• With antimicrobial therapy (1%)

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Cutaneous Anthrax

• 95% of anthrax infections - a cut or scratch on the skin - handling of contaminated animal products or infected animals.

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• Biting insects that have fed on infected hosts.
• Itchy bump that develops into a vesicle and then painless black ulcer.

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Cutaneous Anthrax

Inhalation Anthrax

• The infection begins with the inhalation of the anthrax spore.

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• Spores need to be less than 5 microns (millionths of a meter) to reach the alveolus.

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• Bacterial toxins released during replication result in mediastinal widening and pleural effusions

(accumulation of fluid in the pleural space).

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• Death usually results 2-3 days after the onset of symptoms.

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• Inhalation Anthrax is the most lethal type of Anthrax.

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• Incubation period:
• 1–7 days
• Possibly ranging up to 42 days

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• Case fatality after 2 days of infection:
• Untreated (97%)
• With antimicrobial therapy (75%)

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Gastrointestinal Anthrax

• GI anthrax may follow after the consumption of contaminated, poorly cooked meat.

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• There are 2 different forms of GI anthrax:

1) Oral-pharyngeal

2) Abdominal

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• Abdominal anthrax is more common than the oral-pharyngeal form.

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• Oral-pharyngeal form - deposition and germination of spores in the upper gastrointestinal tract.

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• Abdominal form - the lower gastrointestinal tract, which results in a primary intestinal lesion.

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• Symptoms such as abdominal pain and vomiting appear within a few days after ingestion.

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GI Infection

• GI anthrax cases are uncommon.

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• Incubation period:
• 1-7 days

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• Case fatality at 2 days of infection:
• Untreated (25-60%)
• With antimicrobial therapy (undefined) due to the rarity

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Anthrax in animals

Animal- Anthrax

Important clinical manifestations in animals�

• In ruminants,

Sudden death

Bleeding from orifices - unclotted

Subcutaneous haemorrhage

Sudden bloat in dead animals

without prior symptoms or following a brief period of fever and disorientation should lead to suspicion of anthrax

• In equines and some wild herbivores - transient symptoms such as fever, restlessness, dyspnoea or agitation

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Other animals

• In pigs, carnivores and primates- local oedema and swelling of face and neck

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• Particularly mandibular and pharyngeal, mesenteric lymph node swelling may be present

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Laboratory diagnosis of anthrax

Leaf stained with sheep blood

Pickled meat of goat

All were positive by PCR

Cutaneous anthrax

Photographs of Human, Animal and Environmental Specimens

Universal Precautions for Collection of Specimens

Safety - Personal Protection Equipment (PPE)

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• Gowns, aprons, long sleeves with elastic cuff

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• Disposable gloves

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• Disposable face masks

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Collection of Specimen & transport

• Use of leak proof containers double bagged with ‘biohazard’ label stuck outside.
• Specimens to be processed inside biosafety cabinet (BSC) level II.
• Avoid aerosol formation.
• Sodium Hypochlorite to be used for disinfection process.
• All used materials to be autoclaved or incinerated.

Samples to be collected

Cutaneous Anthrax

• Swabs from the lesion- Collect two swabs as follows:

- In early stage vesicular exudate from the lesions by sterile swab can be collected

- In later stage material to be taken from underneath of eschar after lifting up of eschar with sterile forceps

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• The swab should be put in Carry-Blair transport medium and with another swab smear on microscopic slide may be prepared and heat fixed.

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• Meningitis –Cerebrospinal Fluid.
• Abdominal -Ascitic fluid

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Note: Blood is collected in all forms of anthrax.

How is anthrax diagnosed?

• Gram staining

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• Culture of B. anthracis from the blood, skin lesions, vesicular fluid, or respiratory secretions

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• X-ray and Computed Tomography (CT) scan

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• Rapid detection methods

- PCR for detection of nucleic acid

- ELISA assay for antigen detection

- Other immunohistochemical and immunoflourescence

examinations

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• Biochemiacal findings

Gram Stain Analysis

• Useful for cutaneous and inhalation anthrax.

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• A blood sample or skin lesion is taken from the patient and cultured for 6 to 24 hours.

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• Gram stain takes about 10 to 15 minutes.

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• Identify whether the bacteria come from the anthrax category.

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Bacillus anthracis in Gram stain

PCR Assay

• PCR is a target amplification method of nucleic acid based B. anthracis detection.

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• Provided 100% sensitivity and specificity

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Prevention and control

• The custom of butchering and eating roasted meat from sudden death animals and utilizing their hair, hides, bones.
• Lack of cooperation over reporting sudden deaths
• Long delays in diagnosis due to poor communication and inadequate local laboratory facilities
• Failure to implement policies on disposal of carcasses and subsequent disinfection and decontamination

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Treatment

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• penicillin G
• Stopped for fear of genetically engineered resistant strains
• 60 day course of antibiotics

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• Ciprofloxacin
• fluoroquinolone
• Inhibits DNA synthesis

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• Doxycycline
• Inhibits protein synthesis

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• For inhalational, need another antimicrobial agent
• clindamycin
• rifampicin
• chloramphenicol

Vaccine

• Vaccination is the hub of anthrax control in endemic areas.

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Human vaccine

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• BioThrax/Anthrax vaccine

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• Made by Bioport
• Administered subcutaneously
• 0.5 ml at 0, 2, and 4 weeks, and at 6, 12, & 18 months,
• booster doses at 1 year interval

Animal Vaccine

• STERNE – 34F2

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• The protective effect of vaccine is limited to about 1 year and therefore the animals in enzootic areas must be immunized annually.
• Pregnant animals should not be vaccinated.

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Disinfection�

• Disinfectants should be available in reasonable quantities at veterinary hospitals.
• Veterinary assistants, surgeons and livestock owners should be trained in their use.
• Decontaminate soil seeded by carcasses

Disposal of carcass

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• After confirmation as being a case of anthrax, a carcass should not be opened and should be disposed of by incineration or rendering.

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• Deep burial after disinfection is a favoured option.

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• Necropsy should not be done, as this has the risk of spread of the infection.

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• The carcasses of infected cattle are to be either burnt at the site of death and the ashes buried deeply.

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• Or wrapped in double thickness plastic bag to prevent spilling of body fluids and removed to a more suitable site where they are burnt and the ashes buried.

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• The site where the animal died is to be disinfected with 5% formaldehyde after disposal of the carcass.

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Other measure to control outbreak

• All other animals in the affected herd are to be vaccinated.
• Affected premises are to be quarantined for at least 20 days after the last case or 6 weeks after vaccination, whichever is later.
• Any milk collected from a cow, buffalo or goat showing signs of anthrax within 8 hours of milking is to be destroyed, along with any other milk that may have been mixed with the suspected milk.

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• People entering infected premises are required to wear protective clothing and footwear , which are disinfected before leaving the premises.

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• All cattle on neighbouring premises should also be vaccinated.

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• A buffer zone, 20-30 Km wide, is to be established around the infected area within which all cattle and exposed sheep are vaccinated and quarantined.

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• Persons who have handled infected animals or their carcasses should be vaccinated against anthrax, if their exposure is frequent and if the human vaccine is available.

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• Such persons should avoid any contact with other persons or animals without fchanging clothing, washing hands and taking appropriate disinfection measures.

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• Where there is a risk of aerosolization of spores, further precautions should be considered such as damping down the material, possibly with 5% formalin, wearing facemasks etc

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Continuing research

• Anthrax Immunity Gene in Mice
• Kif1C
• Four varieties (two resistant & two susceptible)

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• Hepatitis drug
• Hepsera
• Blocks the toxic edema factor

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• Monoclonal antibodies
• ABthrax from Human Genome Science
• Phase 1 clinical trials
• Neutralizes protective antigen

��Thank you

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PREVENTION IS BETTER THAN CURE

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Dr.G.Shanmuga Priya,

Veterinary Assistant Surgeon

IVCZ