On Monday, the Centers for Disease Control and Prevention (CDC) issued a health alert after documenting five cases of malaria acquired within the country over the past two months.

The CDC reported four cases in Florida and one in Texas and concluded that the cases were not linked to travel outside of the country.

The last locally acquired case was 20 years ago when eight cases of malaria - plasmodium vivax - were identified in Palm Beach County.

Here's what we know about the latest cases

The cases were locally acquired, but the CDC said all of the patients have now received treatment and are improving.

In both Florida and Texas, the government agency said, "mosquito surveillance and control measures have been implemented in the affected area".

The CDC also said that despite these cases, the risk of locally acquired malaria "remains extremely low" in the US.

However, it has warned that there is a high risk of Anopheles mosquito vectors passing the illness if they feed on a malaria-infected person.

The risk of this happening is often higher in areas where the climactic conditions allow Anopheles mosquitos to survive.

The CDC warned that cases may rise this summer due to increased travel to and from places outside the US.

Last week, the Texas Department of State Health Services was notified of a local malaria case.

The report said the person spent time working outdoors in Cameron County and that the person did not travel outside the country or state.

The department advised Texas residents to wear insect repellents whenever they go outside, to cover up and wear long sleeves and has given further advice on how people can protect themselves from getting bitten.

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The Florida Department of Health also issued a state-wide mosquito-borne illness statement which said its four cases were all reported in Sarasota County.

"Aerial and ground mosquito spraying continues to be conducted in these areas to mitigate the risk of further transmission," it added.

Is there a treatment for malaria?

Yes, there is, antimalarial medicines are used to help treat the illness rapidly.

The CDC said doctors and hospitals should have a plan for quickly diagnosing a malaria patient so they can start administering antimalarial drugs within 24 hours.

What is malaria and what are the symptoms?

According to the NHS, malaria is caused once a person is bitten by an infected mosquito and it can just take up to one bite for a person to get it.

It is mainly found in tropical parts of the world, including Asia and Africa, and Central and South America - it's found in the Dominican Republic, Haiti, parts of the Middle East and some Pacific Islands.

Some of the symptoms of the illness include:

• Flu-like symptoms such as a high temperature, sweats and chills

• Headaches

• Confusion

• Fatigue

• Nausea

• Loss of appetite

• Muscle pains

• Yellow skin

• Sore throat, cough or difficulty breathing

"These symptoms usually appear between seven and 18 days after you've been bitten by an infected mosquito," the NHS website said.

Who is most at risk?

You should always check before you travel to areas that may be heavily populated with mosquitos.

The people most at risk are:

• People who are pregnant

• Young children

• People over the age of 65

• People who suffer from a weak immune system

• People who have no spleen