While the US is making inroads against heart disease, cancer, and HIV, new data unveiled by the Centres for Disease Control and Prevention (CDC) reveal two alarming trends that are responsible for claiming an increasing number of American lives.

Figures released by the CDC on Friday show that deaths caused by drug overdose and gun violence have both risen since 2015, leading to an overall increase in the mortality rate, despite healthcare wins against the biggest killers.

"Heart disease and cancer are traditionally the major causes of death," CDC mortality surveillance researcher Farida Ahmad told CNN.

"What we're seeing here is even though heart disease is going down, even though cancer is going down, the overall death rate is going up."

One of the reasons for this upswing is a significant surge in deaths due to drug overdoses, largely fuelled by the worsening opioid crisis that has gripped the US for years, and which President Trump recently declared a public health emergency.

From the first quarter of 2015 through to the last quarter of 2016, fatal drug overdoses in the US increased from 15.1 people per 100,000 people to 19.7 per 100,000, and are now the leading cause of death for Americans under 50.

While the figures are only preliminary for now, they highlight the growing and complex problem, which threatens the health of both young and old people.

'We have roughly two groups of Americans that are getting addicted," opioid policy researcher Andrew Kolodny from Brandeis University told The New York Times.

"We have an older group that is overdosing on pain medicine, and we have a younger group that is overdosing on black market opioids."

What's even scarier, the crisis looks like it might be accelerating, since the latest yearly jump was bigger than the previous four years combined.

While not as stark an increase, the figures on firearm-related deaths are also not good news.

For the second straight year, the rate for gun-related fatalities has increased, from 11.4 deaths per 100,000 people in Q1 2016 to 12 deaths per 100,000 people for the same period this year.

The good news is that's still significantly lower than the gun death rate in the 1990s – where it reached as high as 15 deaths per 100,000 people. However, it's the second year the gun death rate has risen, following a 15-year period where it mostly held level, and that's not a promising sign.

"The fact that we are seeing increases in the firearm-related deaths after a long period where it has been stable is concerning," CDC mortality statistician Robert Anderson told The New York Times.

"It is a pretty sharp increase for one year."

That increase saw homicides surge from about 9,600 in 2015 to almost 11,000 last year, although the majority of gun deaths are self-inflicted – firearm suicides accounted for about two-thirds of the more than 38,000 lives lost due to guns in 2016.

Ultimately, the new figures mean it's been nearly 20 years since any substantial improvement was made in terms of the rate of gun deaths in the US, according to gun violence researcher Garen Wintemute from the University of California, Davis.

More research into gun violence might help us reduce this alarming death toll, but it's not easy, due to a history of barriers that prevent scientific research on firearms in the US.

What we do know about the impact of firearm regulations is definitely promising though – findings that could one day hold the key to turning these grim statistics around.

The data are available on the CDC website.