The Ebola crisis in west Africa could have been avoided if governments and health agencies had acted on the recommendations of a 2011 World Health Organization commission on global health emergencies, according to an expert.

Professor Lawrence Gostin, director of the O'Neill Institute for National and Global Health Law at Georgetown University, Washington DC, has called for renewed international commitment to a health systems contingency fund to prevent another infectious disease catastrophe.

Writing in The Lancet, Gostin advocated long-term funding for ensuring the development of health systems.

On Thursday, WHO stated that more than 3,500 people have been infected with the disease and at least 1,900 have died in Liberia, Guinea, Sierra Leone and Nigeria.

"The outbreaks are racing ahead of the control efforts in these countries," WHO chief Margaret Chan said, the BBC reported.

Although WHO has now put into practise a plan for dealing with Ebola, five months after the virus first began to spread internationally, implementation will be further delayed while US$490m (£293m) is raised to meet the cost of tackling the epidemic, according to Gostin.

In the meantime, Ebola continues to escalate amongst health workers and the general population, in countries where health resources were already strained before the outbreak.

In 2011, the WHO Review Committee proposed a Global Health Emergency Workforce, backed by a US$100m contingency fund, which would have enabled the rapid initial response needed to contain the Ebola outbreak.

However, due to a lack of sufficient financial commitment from governments in high-income countries, the proposal was not acted upon.

"How could this Ebola outbreak have been averted and what could states and the international community do to prevent the next epidemic?" Gostin wrote.

"The answer is not untested drugs, mass quarantines, or even humanitarian relief. If the real reasons the outbreak turned into a tragedy of these proportions are human resource shortages and fragile health systems, the solution is to fix these inherent structural deficiencies."

He adds that a dedicated International Health Systems Fund at WHO would rebuild trust, with the returns of longer, healthier lives and economic development far exceeding the costs.

"This fund would encompass both emergency response capabilities and enduring health-system development," Gostin wrote, saying that the most recent Ebola outbreak could spark a fundamental global course correction that would favour strong health infrastructure.

"It is in all states' interests to contain health hazards that may eventually travel to their shores. But beyond self-interest are the imperatives of health and social justice — a humanitarian response that would work, now and for the future."