At first glance this question might seem like a no-brainer. Surely if you make an infectious disease notifiable then you are better able to contain infection and prevent it spreading, right? Unfortunately, whilst the principle seems simple, the reality is far less so and there are a host of other factors that must be considered that will influence the success of such a ruling. Depending on where an individual sits within the system may also greatly influence their stance on the topic. Here we will take a look at the different facets and implications of making an infectious disease notifiable.
What does it really mean to make a disease notifiable?
A notifiable disease or causative agent is one which, by law, must be reported to the appropriate authority if suspected or diagnosed.
In the UK, if a medical practitioner suspects a case of any notifiable disease (of which there are 32 in the UK), they have a duty to report it to the proper authority – the local health protection team. Likewise, all UK laboratories performing primary diagnostic testing are obliged to report the confirmation of any notifiable organism (of which there are 60 in the UK).
Public Health England produces weekly reports using this data to identify trends in disease occurrence and if necessary take action to prevent further spread. This form of public health surveillance is therefore important for developing strategies to reduce and eradicate (if possible) disease within the population, assess the effectiveness of vaccination strategies, as well as pinpointing sources of disease. It also provides vital early warnings of possible outbreaks, epidemics and pandemics, enabling preparation of treatment medications or vaccinations and quarantining of groups or individuals if appropriate.
Depending on which country you are in, the diseases and causative agents that are notifiable are different, and sometimes will even vary from state to state within the same country.
Others, such as cholera, plague and yellow fever in humans, are notifiable on a global scale and are reportable to the World Health Organization (WHO). The World Organisation for Animal Health (OIE) administers the reporting of globally notifiable animal disease. This situation is not always straightforward as some globally reportable diseases, such as equine influenza, are not reportable in all countries individually.
Why is a disease made notifiable?
Not all infectious diseases are notifiable, for example no-one is going to be reporting a common cold. So, what determines which ones are notifiable? Some of the main factors are likely to be the severity of the disease it causes, the impact on a larger scale, how easily it spreads and what measures are available to reduce or contain it. The presence or absence of a vaccination program plays a significant part too. The recent measles outbreaks that have been plaguing a number of places including New York are a great example. The disease can be severe, causing permanent damage and death, and has brought into sharp focus the negative impact of the breakdown in herd immunity due to the number of unvaccinated people. Armed with this data, places such as Italy have taken the public health action to ban unvaccinated children from school and areas of New York have imposed fines of $1000 for any unvaccinated people to reduce spread and boost vaccination rates.
So, what happens when a case is notified and what are the implications?
This will very much depend on which disease it is and where it is. A recent example has been seen with the 2007/2008 outbreak of equine influenza in Australia. In response to rising case numbers following a biosecurity breach, the authorities imposed movement restrictions and instigated a mass vaccination program. Likewise, the outbreak of foot and mouth disease in the UK in 2007 lead to widespread movement restrictions and preventative culling, but ultimately enabled the source of infection to be traced and the outbreak contained. In the case of foodborne illness, tracing the source of infection using surveillance data can mean that other contaminated foods are removed from sale and recalled before they make others ill.
The good, the bad and the ugly
Don’t get me wrong, there can be many upsides to a disease being notifiable. The eradication of smallpox and rinderpest for example were certainly aided by their notifiable status, enabling remedial action to be taken in a timely manner. And as already highlighted, measles is currently in the crosshairs thanks to its notifiable status. Notification status can be vital in the fight against disease: however, it doesn’t bring only positives.
With notifiable status comes an onus to do something about it, and that can come at a price, monetary and otherwise. There’s the cost of testing, the cost of treatment or vaccination and the problems that movement restrictions or isolation may bring to life and livelihood amongst others. The impact will depend on the disease and your location, and the question is, who picks up the bill?
Take tuberculosis (TB), caused by the bacterium Mycobacterium tuberculosis, for example which is amongst the notifiable diseases and causative agents in the UK and U.S. amongst others. TB is persistent and worryingly showing rising levels of antibiotic resistance. Consequently, it can take many months of antibiotic treatment to clear the infection. If diagnosed in the UK, testing and treatment costs will be covered by the National Health Service. But not all countries are lucky enough to have such a service and treatments may be expensive or just not available.
TB cases may not always be immediately obvious where infection is latent and consequently screening in close contact environments, such as prisons where it can be easily transmitted, is very important. However, if cases are identified, then affected individuals must be treated and prevented from spreading it to others, which can be a challenge in the prison health system. Consequently, concern has been voiced about the neglect of TB diagnosis and treatments, especially in countries where the resources to do anything about the problem are lacking.
Whilst laboratories, vets and medics are obliged to report suspected notifiable cases, and in some countries obligation extends to the public, there will always be a temptation for those who will bare the brunt if a notifiable disease were to be declared to keep quiet and let it pass. Underreporting has been shown to be an issue for both human and animal disease and can compromise the effectiveness of surveillance and control schemes.
Should it, shouldn’t it? Thrashing out the argument for adding another disease to the hit list
Strangles, the most commonly diagnosed equine infectious disease worldwide, caused by the bacterium Streptococcus equi (S. equi) is an interesting case. Whilst not notifiable globally to the OIE, strangles is notifiable in some countries including Australia and in some U.S. states. Whilst Australian racing yards can be subjected to spot checks to ensure compliance with disease reporting, they are offered support for testing and treatment costs. Not so for anyone else however, owners must pick up the bill themselves. For pet animals this can be expensive and a nuisance but for breeders and riding stables who rely on their animals for their livelihood, it can mean bankruptcy. With effective diagnostic tests available for strangles, and proven management systems there has been pressure to make the disease more widely notifiable. However, it is all well and good to make a disease notifiable but if there is neither the will nor resources to do anything about it then efforts will be ineffective. The case of strangles is even more complicated by the fact that it is endemic in every single country in the world with the exception of Iceland.
Dr Richard Newton, Director of Epidemiology and Disease Surveillance at the Animal Health Trust in Newmarket, UK, commented “Making a prevalent disease such as strangles notifiable in the UK would be likely to be problematic and probably even counterproductive as the confirmed diagnoses of the disease would be likely to be drastically reduced, making it harder to properly control spread of the disease. However, there may be value in making it an OIE listed disease.” He explained “Due to the extensive international movement of horses, making pre-export testing mandatory for all countries could prevent many new outbreaks from happening. In 2017, Dubai implemented compulsory testing of animals prior to permitting them entry to the United Arab Emirates, and collected data indicates that they have in all probability averted many incursions of the infection that causes strangles and consequent outbreaks.”
So, in conclusion, there really is no right or wrong answer or magic bullet to this debate. In an ideal world where money doesn’t matter, from a purely disease control aspect, notifiability could be a great tool to reduce disease. However, it needs to be backed up by the support required for those affected.