Avian influenza outbreak investigation and containment.

Influenza A viruses cause pandemics at recurring yet unpredictable intervals. The past three pandemics had origin from birds. Although the viruses of avian influenza are not easily transmitted to humans, this may change due to either mutation or genetic reassortment. There is still an opportunity to pre-empt the pandemic. It is believed that if the surveillance system for animal health is able to detect infection in poultry quickly followed by rapid and safe culling of infected and exposed poultry and the surviellance system for human health is able to detect first human cases quickly followed by rapid containment measures including strategic use of antiviral drugs, the pandemic could be averted. This article discusses the principles and major steps of avian influenza outbreak investigations and containment.

Anthrax.

Anthrax is caused by Bacillus anthracis, an encapulated and spore-forming bacillus. The disease is usually contracted through uptake of spores that remain viable in the contaminated soil for many years. Anthrax is primarily a disease of herbivorous animals and is uncommon in humans who may get the infection through contact with contaminated animals or their products. Anthrax spores germinate after entering the body through skin abrasions (cutaneous anthrax) or by inhalation (inhalation anthrax) or ingestion (gastrointestinal anthrax) and multiply to produce two exotoxins which determine the virulence along with capsule. Although most cases occur within 48 hours of exposure, germination of spores may occur upto 60 days later. While inhalation anthrax is almost always fatal, intestinal anthrax results in death in 25% to 60% of cases. Upto 20% of cases having cutaneous anthrax may die. Antibiotics are effective if the disease is recognised early and treated appropriately. Penicillin is the drug of choice when disease occurs in natural setting. Ciprofloxacin is recommended when aerosols of anthrax spores are used as bioweapon, prophylactic antibiotics should not be prescribed until risk of exposure is considered real by experts.