Symptoms may develop as soon as seven days after arrival in a malarious area, or as long as six months after leaving a malarious area. Symptoms of malaria are often beguilingly mild in the initial stages, resembling influenza. It is worth emphasising that these symptoms may not be dramatic, and can easily be mistaken for an attack of influenza or similar non-life threatening illness. Deterioration can then be sudden and dramatic, with a rapid increase in the number of parasites in the victim's blood stream. A high swinging fever may develop, with marked shivering and dramatic perspiration.
Cerebral malaria is extremely serious, with the victim becoming delirious and entering a coma.
Cerebral malaria is frequently fatal, and it is extremely important that all suspected cases of malaria should receive urgent medical attention. All persons possibly exposed to malaria who develop any influenza like illness or fever within seven days of entering, or six months of departing a malarious area should seek immediate medical attention, and have urgent blood tests taken to check for possible malaria infection. It may be sensible to have a second blood test taken if a first test is negative for malaria, to be certain of excluding the disease. Prevention relies on measures to reduce bites, and taking anti-malaria medication appropriate both for the destination and the traveller. Any traveller developing influenza like symptoms or fever within three months of return from a malarious area should be tested for malaria, even if taking preventive measures.