Anthrax transmission unlikely through insects, dairy products

By R. Prasad

CHENNAI, OCT. 17. Transmission of anthrax-causing bacterium, Bacillus Anthrasis, through blood-sucking insects may be possible. However, this can happen only if there is deposition of blood from the infected person on some lesion. Anthrax bacteria, unlike malaria, do not use any blood-sucking insects to complete its lifecycle. Chances of transmission through blood sucking insects therefore, are very remote, according to Dr. M. K. Lalitha, Professor of Clinical Microbiology, CMC, Vellore.

Transmission through milk, egg or other dairy products can also be ruled out as the bacterium is very invasive and can enter the bloodstream from the gut in a couple of hours, leading to the death of the animal. ``The very short incubation time seen in anthrax prevents transmission through milk or egg products,'' she said.

In most cases, there has been a direct correlation between the infected animal and humans, according to Dr. H. V. Batra, Senior Scientist, Defence Research and Development establishment, Gwalior.

Transmission from animals to humans is seen only when uncooked contaminated meat is consumed or when humans with lesions come in contact with dead animals infected with the bacteria.

In humans, the incubation period is around 2-5 days when the transmission is through the cutaneous route. However, it is hardly two days when it is inhaled. Transmission of anthrax through blood donation is very slim as the person will be too sick to donate blood once the bacteria enter the blood, according to Dr. Lalitha. Even when persons harbour the bacteria for a relatively longer time when infected cutaneously, transmission through blood donation is remote as it takes a long time for the bacteria to enter the blood stream - may be as long as three days. At present, vaccine against anthrax is available only for animals and antibiotics are the only recourse for humans in India. Though antibiotics are effective in getting rid of the bacteria, they would be effective as a prophylactive only for a few days.

Anthrax infection among animals can be easily identified by the presence of bloody discharge through all orifices and large number of animals dying all of a sudden.

The disease in animals is endemic to only four States in the country as the bacteria, though highly resistant to environment, are not widespread. ``This is because the bacteria settle to the ground after the animal's death. For wider prevalence, the bacteria need to be in an aerosol form,'' said Dr. Batra.

Postal sanitisation

PTI reports from Mumbai:

Sanitising postal envelopes using ultraviolet (UV) radiation was a simple procedure that could be adopted by post offices to check exposure to anthrax spores through mail, according to an expert of UV sanitation for drinking water and air, Professor Yogendra L. Shethna.

``All that is required are powerful UV tubes or lamps over and below a quartz plate and envelopes must be exposed to the light for five minutes'', he said. ``If a powerful lamp (of 100 watts) is used, even five minutes' exposure may not be necessary'', Prof. Shethna said in a statement.

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