Sri Lanka was certified malaria-free on Monday, making it the second country to reach this status in the World Health Organization's (WHO) region of South-east Asia.

The first was the smaller island nation of the neighboring Maldives in 2015, aided by its much smaller population of nearly 400,000, compared to more than 20 million in Sri Lanka.

Globally, 33 countries have been certified as malaria-free, with Armenia, Turkmenistan and Morocco the most recent to join the list before the Maldives in 2015. But more than 95 countries and territories had ongoing malaria transmission in 2015 -- now down to 94.

Sri Lanka's status of ridding itself of the disease was against the odds according to some experts, due to the country having had high burdens of the disease, its status as a low to middle-income country, regular movement of people between the island and India, and more than 20 years of civil conflict that only recently came to an end.

But they managed to do it -- and set a precedent for malaria control in other parts of the tropics.

"It was a hard fight, [but] this is an example to the rest of the world," said Dr. Pedro Alonso, Director of the WHO Global Malaria Programme. Sri Lanka "has sustained this for the last three years in a convincing way."

The country's ministry of health used multiple strategies to end a disease that otherwise continued to infect 214 million people globally in 2015, and kill more than 400,000. But the journey to end malaria in Sri Lanka has been a long one.

Ending a disease

"Sri Lanka famously nearly eradicated malaria before," said Dr. Jo Lines, a malaria control expert from the London School of Hygiene and Tropical Medicine.

The country came close to eliminating malaria in 1963, when numbers reach just 17 cases that year, compared to 2.8 million cases in 1946, according to Alonso.

But it didn't last.

"It is a prime example of what happens if you don't finish the job," said Alonso. "They nearly got there, relaxed and [malaria] came back in an awful way."

A resurgence of the disease in 1967 was then followed by more than four decades of infections reaching up to 500,000 in number each year. Then in the 1990s, the country developed a new, somewhat unorthodox strategy, according to some experts -- it prioritized hunting down the parasite as well as killing the mosquito.

Malaria is caused by the Plasmodium falciparum parasite, carried by anopheles' mosquitoes as they feed on humans and pick up the parasite inside their blood. The goal set out was therefore to treat people as soon as possible to kill the parasites lurking in their blood stream and leave nothing behind for mosquitoes to suck up -- preventing further transmission.

This was helped by setting up mobile malaria clinics that diagnosed and treated people much earlier than waiting for people to visit their doctor with symptoms, accompanied by regular surveillance, community engagement and education programs to make sure people knew the symptoms and when to get tested and treated.

Alonso added that there was an aggressive effort to find infected humans by Sri Lanka's department of health, but he also stressed the importance of the government prioritizing the problem and funding it, as well as continuing mosquito control efforts. "Sri Lanka has done both," he said.

"In many places at the moment, we are over-reliant on insecticides ... you're not going to succeed if you put emphasis on just one part of the story," said Lines. "They looked for the last remaining parasites in all their hiding places."

Reaching zero

Sri Lanka recorded less than 1,000 cases of malaria per year by 2006, and endemic cases within Sri Lanka -- not imported from another country -- have been zero since 2012.

No local cases have been recorded for more than three years, which is the timeframe needed for a country to be certified as free of the disease.

The challenge now is keeping the parasite away and maintaining this status.

Last year Nigeria was declared free of polio after years fighting the paralyzing disease in children, but three infections returned in the population this year, showing the ease with which an infection could re-enter.

"It's about making elimination stable," said Lines. "To make sure there isn't another monster explosion."

Alonso believes it will be sustained and that all the necessary measures are in place to prevent the re-introduction of the disease. "They're in a good position," he said.

Can the world be malaria-free?

The global malaria eradication program set out to make the world malaria-free when it launched in 1955. It succeeded in eliminating malaria from Europe, North America, the Caribbean and parts of Asia and South America, but high numbers continued in Africa, and other parts of South America and Asia, including Sri Lanka, causing the goal of ending malaria globally to be abandoned in 1969.

The 94 countries of the world that remain endemic for the disease can learn a few key strategies from Sri Lanka, say experts, namely the importance of owning the problem.

"True ownership is essential," said Alonso. "If countries own the problem, and the solution, and scale up interventions ... it would go very, very far."

Lines agrees that this commitment would mean countries then take all the measures needed, such as using bed nets, insecticides and treatment in combination with broader factors such as better housing, removing breeding sites for mosquitoes and improving diagnosis.

"We all know it, but doing it is the difference," said Lines. "Sri Lanka did it in a coordinated, well-planned and sustained way."

(CNN)