(Question 15) Discuss the following (fictional) press release:
“The world is a safer place with the advent of a new vaccine against tuberculosis, announced the Health Minister during a visit to Gambia. The vaccine should be available to treat disease caused by the tubercle virus within two years, but travellers are warned to continue boiling water and avoiding contact with mosquito-infested water”
Answered by Nicole Hendricks...
The preceding press release is misleading on many fronts.
Tuberculosis does present a major global disease burden accounting for approximately 1.7 deaths each year. Incidence is more prominent in third world countries (of which Gambia is one) when compared to developed countries such as Australia. This is in part due to our access to direct health care, infrastructure and recourses that support quick and accurate diagnosis as well as the identification and treatment of ‘at risk’ populations such as migrant and indigenous Australians.
80 precent of the world tuberculosis cases are contained within 22 high burden countries- 10 of which are in Africa (Nigeria, South Africa, Ethiopia, the Democratic Republic of Congo, Tanzania, Kenya, Uganda, Zimbabwe, Mozambique, and Sudan). There is also an increased association of drug resistant tuberculosis and HIV/tuberculosis co-infection in nations which struggle with treatment compliance and have increased risk factors such as poverty, poor health care and malnutrition- factors which may compromise the immune system and therefore assist disease acquisition and progression. For this reason the health minister was correct to inform travellers to take precautions when travelling overseas- particularly if they are travelling to one of the 22 ‘high burden’ nations. Though, while there is an increase in tuberculosis incidence in Gambia when compared to Australia, it is not of primary concern.
A major flaw in the Health Ministers press release is that he referred to tuberculosis as a virus- in reality it is a bacterial disease (causative agent Mycobacterium tuberculosis). Also the Health Minister infers that protection may be achieved through boiling water and avoiding contact with mosquito infected water- while these are both worthy ‘travel tips’, particularly since infectious diseases such as cholera and malaria are prominent in Gambia and risk of infection may be reduced by these respective techniques, they infer no protection against tuberculosis.
Rather, tuberculosis is spread though the inhalation of infected aerosol droplets (usually less then 5um) often produced by the cough, sneeze or speech of an infected individual. Furthermore, many of the symptoms of tuberculosis (fever, headache, cough) are common to a cold or flu and an individual may carry the disease but remain asymptomatic therefore providing an opportunity for disease transmission. For these reasons avoiding prolonged close proximity with suspected infected persons, staying in well ventilated areas or wearing a mask in high risk places would be more appropriate in order to avoid tuberculosis infection.
Finally, while the development of a new vaccine is very exciting and is part of the hope of one day eradicating tuberculosis globally- the current vaccine and treatments must not be ignored as they have been in the press release. Bacillus Calmette-Guerin (BCG) is an attenuated form of the tubercle bacterium which initiates immunological memory upon exposure to the infection. While BCG is not offered at birth in Australia it is available in high risk situations (such as for travellers to high risk countries) there are few side effects, is relatively cheap, it does not interfere with other vaccines and has been found to be protective (preventative) in up to 80 percent of cases.
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2 comments:
very good point about the false reference to viruses; I missed that!
Great points there Nicole. The statement also seems to imply that a vaccine will fix everything. The problem however with the tuberculosis vaccine we have now (BCG) is that it is does not work in people who already have the disease, or in people who have been exposed to other Mycobacterium infections. Even when it is used in people without the infection (i.e. given at birth as a preventative measure) it only provides protection for those under 5 and not in adults with the more serious pulmonary TB (which is far more contagious and life-threatening). Additionally, the statement also says that the vaccine will not be available for another 2 years - so what do we do in the mean time?
The use of both anti-tuberculosis drugs and vaccines is undeniable in continuing the struggle against TB, but with it comes concern of encouraging further drug resistance. The current emergence of XDR-TB crisis has taught us of the need for proper stewardship of the drugs we already have, otherwise we are only going to abuse and misuse any future drugs and vaccines, rendering them ineffective.
Also, there is still the need for responsibility on behalf of governments, communities, and above all, the individual, because if they don't do their part to combat TB then there will never be the opportunity to eradicate it - we need to provide a unified front against TB. We have a duty to reach out to all those in need of care, because it is only when we provide true support to the developing world will it ever be possible to eradicate TB.
Science is crucial, but alone it is not sufficient to control TB - vaccines might provide hope, but unless we all do our part then a TB epidemic could soon emerge out of the developing world and land on our doorstep here in Australia.
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