The answer is : a quinine prophilaxis is required before, and during the Amazonas crossing.
Usually is the ships cruise Company that provide -it on bord -for 10 days- one tablet a dayly, if i remember well.
Pls ask to your phisician the daily intake , and also ask the Company.Keep your camera ready , because every morning you will found lot of marvelous -coloured butterfly relaxing- on the big windows around the swimming pool.
Ask everybody to please do not disturb them, they are slipping, and meantime accompany you during the cruising of Amazonas without flying.Ask the Company if a the ship will call at Boca da Valeria .The most beautiful "indios caboclos" village.Usually they call at BOCA.
DEAREST OGG ,HAVE A NICE AMAZONAS CROSSING. BRING A COMPUTER WITH YOU , BECAUSE THERE'S LOT OF THINGS YOU SHOULD REMEMBER.
FULVIO FROM SAVONA ITALY