The 'godzilla' weather phenomenon El Niño in 2015-16 has been blamed for the worldwide surge in cases of killer viruses.
The natural occurrence, caused by warm water shifting in the Pacific ocean, changes weather conditions across the planet. The one that struck three years ago is the strongest on record.
During the 2015-2016 event, the precipitation levels and vegetation created the perfect conditions for dengue fever, cholera and the plague to spread, researchers have said.
It had devastating effects throughout the world, including causing a spike in infections in Colorado, New Mexico, Tanzania, Brazil and Southeast Asia.
The research is believed to be the first study, by NASA, to assess the public health impacts of the major climate event on a global scale.
Experts believe it could serve as a 'remarkable tool' to save lives in the future, building on existing models that predict outbreaks.
The 'godzilla' weather phenomenon El Niño has been blamed for the worldwide surge in cases of killer viruses including the spread of hantavirus and the plague in Colorado and New Mexico, cholera in Tanzania and dengue fever in Brazil and SE Asia
El Niño, along with its little sister La Niña, are part of a recurring shift in climate that occurs as warm water shifts from one side of the Pacific to the other.
It is caused by a shift in the distribution of warm water in the Pacific Ocean around the equator.
The 2015–16 El Niño was 'record-breaking' and one of the three strongest events since 1950.
'The impact on weather and therefore diseases in these regions was especially pronounced,' said Assaf Anyamba, a research scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who was lead author of the study.
The study, published in the journal Nature Scientific Reports, used a number of climate datasets and public health records to quantify a relationship between disease outbreak and El Niño.
Reported cases of plague in Colorado and New Mexico were at their highest in 2015, while the number of hantavirus cases reached their peak in 2016.
El Niño, along with its little sister La Niña, are part of a recurring shift in climate that occurs as warm water shifts from one side of the Pacific to the other.
It is caused by a shift in the distribution of warm water in the Pacific Ocean around the equator.
Usually the wind blows strongly from east to west, due to the rotation of the Earth, causing water to pile up in the western part of the Pacific.
This pulls up colder water from the deep ocean in the eastern Pacific.
However, in an El Niño, the winds pushing the water get weaker and cause the warmer water to shift back towards the east. This causes the eastern Pacific to get warmer.
But as the ocean temperature is linked to the wind currents, this causes the winds to grow weaker still and so the ocean grows warmer, meaning the El Niño grows.
This change in air and ocean currents around the equator can have a major impact on the weather patterns around the globe by creating pressure anomalies in the atmosphere.
Hantaviruses are a family of viruses spread mainly by rodents through urine and feces and plague is usually found in small mammals and their fleas.
According to the study, the spike in both potentially fatal diseases was an El Niño-driven increase in rainfall and milder temperatures over the American Southwest.
This spurred vegetative growth, providing more food for rodents that carry hantavirus who are in frequent contact with humans.
As their rodent hosts proliferated, so did plague-carrying fleas.
A continent away, in East Africa's Tanzania, the number of reported cases for cholera in 2015 and 2016 soared to record numbers since 2000.
Cholera is a potentially deadly bacterial infection of the small intestine that spreads through fecal contamination of food and water.
Increased rainfall in East Africa during the El Niño allowed for sewage to contaminate local water sources, such as untreated drinking water.
'Cholera doesn't flush out of the system quickly,' Anyamba said, 'so even though it was amplified in 2015-2016, it actually continued into 2017 and 2018. We're talking about a long-tailed, lasting peak.'
In Brazil and Southeast Asia, during the El Niño dengue fever proliferated. In Brazil the number of reported cases for the potentially deadly
