Three people from the Madeira archipelago have returned home for Christmas holiday after working in the Central African country of Equatorial Guinea are hospitalized due to infections of falciparum malaria.

One of the workers is in intensive care while the other two are in the hospital but stabile.

The Madeira archipelago is one of the autonomous regions of Portugal in the mid-Atlantic Ocean. It does have a sub tropical humid climate which is conducive to many emerging diseases found in the tropics. But according to experts, the weather in December is too cold for local transmission.

Malaria is endemic in Equatorial Guinea where the workers were located and transmission is very possible for visitors to the country without appropriate prophylaxis.

Portugal had 41 cases of imported malaria in 2008.

It is estimated to be up to a half a billion cases of malaria annually with about 1 million deaths, particularly among young children.

The disease may manifest itself after an incubation of days to months. Once the parasites build up in the blood, symptoms are non-specific; fever, chills, body aches, diarrhea and vomiting. At this point the only way to confirm is finding the parasites in blood. These early stages resemble many other febrile diseases.

Paroxysms (due to rupture and release of the parasite and metabolic products into the system), happen every 48-72 hours depending on the species.

There is a cold stage which leads to teeth chattering, shaking chills followed by a hot stage (fever) where temperatures may reach 106°F. Convulsions may develop particularly in children.

Untreated P. falciparum (the life-threatening species) can lead to severe malaria. Severe malaria is characterized by cerebral malaria, severe anemia, renal failure (black water fever), respiratory distress and bleeding disorders and shock.

Prompt treatment for falciparum malaria is essential because death from cerebral complications may occur.