Recent epidemics such as Ebola and now the Zika virus highlight the increasing vulnerability of the world and economic activity to disease.

The risks of a serious pandemic are rising. Viruses, such as Ebola, remain poorly understood and difficult to treat. Future epidemics are inevitable as there is a reservoir of known and unknown viruses which may be transmitted to human beings.

Zoonosis, the transfer of viruses from animal hosts to humans, is increasing as human populations penetrate more remote, previously uninhabited areas. If they reach major urban centres, then such infections may be difficult to contain.

There is today a lack of investment in vaccines and therapies for treating new and rare diseases. As Ebola historically was a disease confined to poor African countries, pharmaceutical companies were unwilling to invest in possible cures or vaccines as the potential revenues were low. In the absence of public subsidies or funding, developers fear that they will not be allowed to make adequate returns from drugs to deal with such epidemics.

Meanwhile poor countries with underdeveloped health infrastructures act as loci for propagation of diseases. Inadequate health systems and poor sanitation were crucial in the Ebola crisis.

Lack of public awareness and education assisted the spread of the virus. Sierra Leone spends only $300 per person on healthcare, compared to more than $8,000 in the US. Guinea has 10 doctors per 100,000 people, compared to 245 in the US.

Preparedness for an epidemic is poor. In Western countries with better facilities and procedures, the fatality rate for Ebola may have been significantly lower. But there is limited experience in dealing with such complex diseases and intensive treatment regimes, especially where needed. Infections in hospitals in the US and Spain highlight the inadequate readiness to cope with a major epidemic.

Finally, the well-documented rise in drug resistance is likely to increasingly limit treatment options for some diseases. Resistance and reducing effectiveness is inevitable whenever drug treatment is the main method of control. Misuse of medication, especially antibiotics, contributes to the problem. The emergence of drug resistant malaria, HIV, TB or other infections is a major problem.

Some scientists believe that the world may be on the cusp of a post-antibiotic era, where common infections become untreatable and surgery and cancer therapies, reliant on antibiotics, are unusable.

The preliminary findings of the UK Review on Antimicrobial Resistance, led by former Goldman Sachs economist Lord O’Neill, which was released in July 2015, found that drug resistant infections will cause 10 million deaths a year worldwide by 2050 – more than cancer. The estimated economic cost would be at least $100tn and potentially as much as $200tn over the next 35 years.

The Ebola epidemic was newsworthy because of its exotic, horrific symptoms and high fatality rate (around 60 per cent). But it is not highly contagious: infection requires direct contact with infected bodily fluids, such as blood or vomit. This meant the epidemic, while devastating, was localised.

In 2002-03, SARS, a respiratory illness originating in Southern China, affected Southeast Asia. Spread through contact with respiratory droplets, produced when an infected person coughs or sneezes, it was very contagious and spread rapidly to over two dozen countries. It infected over 8,000 people, causing around 800 fatalities. It cost the global economy around $40bn.

Prepare against the next big pandemic: Pro

Today, a variety of diseases have the potential to develop into global threats. Other than Zika, there is the MERS virus. Chikungunya, a viral disease with high fever and terrible joint pain, is a problem in the Caribbean and South America, with hundreds of thousands of cases. Dengue fever is another example. Like Zika, the latter are both spread by mosquitos which (unlike those that spread malaria) are well adapted to urban environments.

Increased urbanisation, with the close proximity of large populations, makes rapid transmission possible. Movement of large numbers of people as a result of modern air travel has profound implications for the spread of infectious diseases.

The world is poorly prepared to deal with a serious pandemic. The Ebola epidemic was exacerbated by poverty, lack of development, inadequate health facilities, lack of education and weak governments in countries affected by conflict that were mistrusted by the population.

Without adequate investment in public health, the risk of epidemics to human life and economic activity will continue to increase.