Swine flu vs BSE

Under control

What can we do to prevent pandemics?

1. Eliminating infected animals

Mass culling was used during the UK foot and mouth disease (FMD) epidemic in 2001. Culling has also been used to contain H5N1 avian flu, which can be deadly to humans. In 1997, after the first human cases, the Hong Kong authorities slaughtered the country’s entire poultry population – 1.5 million birds – in just three days. The disease was contained but at huge cost. And the virus has since reappeared and spread through wild birds and via the international poultry trade. It is continually circulating in poultry in Bangladesh, China, Egypt, Indonesia and Vietnam.

Though often effective, mass culling has its problems. In the UK FMD outbreak the culling policy led to the slaughter of 4 million animals. A similar number of cattle were slaughtered to prevent bovine spongiform encephalopathy (BSE) entering the food chain in the UK in the 1990s. BSE is a brain disease that involves wrongly folded proteins called prions. It can be transferred to humans as variant Creutzfeldt–Jakob Disease (vCJD) when someone eats contaminated parts of cows.

In the BSE outbreak inadequate compensation led some farmers to break the rules. Bovine tuberculosis also poses a continuing threat to farmers’ livelihoods, as they must slaughter infected animals. Cattle can be infected not just by other cattle but also by wild badgers. A similar situation in a developing country could be disastrous. Who would compensate poor farmers told to slaughter their chickens to prevent a global epidemic of disease?

2. Vaccination

Although vaccines often exist, trade restrictions may hinder their use – a vaccinated animal is hard to distinguish from an infected but healthy-looking one, so countries may not admit them. In many places it is not practical to vaccinate huge numbers of animals. And for diseases such as flu, a vaccine may protect against some strains but not others.

3. Drugs

For bacterial infections, antibiotics are effective – but to varying degrees. The biggest challenge is from antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile and Neisseria gonorrhoeae. Tuberculosis (TB) is also a major problem as it is very difficult to kill, and strains resistant to multiple antibiotics have appeared.

The medicine chest for viruses is even less well stocked. After avian flu strain H5N1 was found in early 2007 on a British turkey farm, 176 workers were given the antiviral drug Tamiflu (oseltamivir). This can prevent infection and improves the chances of survival of those already infected – but only if given early in infection. Resistant strains of the virus have already been seen in South-east Asia. Between 2003 and 2012 an estimated 400 million birds were slaughtered due to H5N1 infections, and 359 people died after being infected. The number of affected countries has risen above 60. Most governments are stockpiling oseltamivir for use in a possible pandemic.

4. Public education

It sounds simple, but teaching people about taking medicines properly and about sanitary practices in the home and backyard can also have a big impact on disease control.

Lead image:

Janhamlet/Flickr CC BY NC

References

Further reading

About this resource

This resource was first published in ‘Epidemics’ in September 2007 and reviewed and updated in January 2015.

Topics:
Microbiology, Health, infection and disease, Immunology
Issues:
Epidemics, Populations
Education levels:
16–19, Continuing professional development