Infectious diseases are very widely spread in PNG due to the lack of proper waste water treatment in many places, tropical climate and poor hospital infrastructure.
PNG is also a country with a moderate risk for malaria infections.
The most likely problem you are going to experience when travelling there are tropical ulcers. Any cuts and scratches get infected very quickly and might develop into a serious infection that requires you to take a course of antibiotics.

Malaria

Malaria infections are not a great risk for cruising visitors because you are not likely to encounter mosquitos as long as you stick close to the sea shore. If you go inland on an island with fresh water sources or stay at the beach after sunset make sure to bring insect repellent. Moskito coils and nets are also a good idea to bring.
There are also various different medications to prevent malaria infection (This will not be a 100% protection, but will make an infection less likely.). However, some of them have very undesirable side effects or are very expensive.

• Lariam - for a long time the most popular malaria prevention treatment, but many people suffer from nausea during the course and it can cause depression in women.
• Doxicyclin - is originally only used as an antibiotic. However, since it proved useful in preventing malaria infections it is now used in many countries for this off-label use. This is also due to the fact that is the most affordable choice, but it makes your skin more sensitive to UV-radiation, hence you are much more likely to be sunburned.
• Malerone - is the most recent and most expensive product on the market. So far no major side effects have shown up. Another advantage of this drug is that it can be used for preventive treatment as well as emergency treatment once malaria symptoms appear.

Tropical ulcers

Tropical ulcers are very dangerous, because they are usually underestimated and develop quickly into serious infections.
Cuts and scratches need to be disinfected, cleaned and dressed. If they are not covered flies and dirt pose a major risk of infection. So bring enough antibiotic/antibacterial cream and a couple of courses of antibiotics.
Furthermore, the 'cruising' lifestyle makes it hard to keep cuts and scratches dry and clean.
So make sure your ships medical kit is well stocked with band-aids, antibiotics and anti-malaria treatment.

Schistosomiasis

Schistosomiasis (also known as bilharzia, bilharziosis or snail fever) is a parasitic disease caused by species of fluke of the genus Schistosoma living in fresh water snails. Symptoms are fever, bloody urine and bloody diarrhea.
You can catch these parasites in fresh water streams. So think twice if you really need to give in to that craving of a fresh water bath.
The treatment for this disease is quick and easy, but it must be treated to prevent permanent organ damage.

Other prevalent diseases of the area

• Tropical ulcers (Staphylococcus infections)
• Tuberculosis
• Hepatitis A/B
• Various STDs, incl. HIV

Medical Kit

The master of an Australian registered ship has the right to carry various prescription drugs on board for emergencies. However, some GPs, who need to give you the prescription first, do not know that. So better take all the necessary documents (ship's papers and some print out of the regulations) along with you to avoid queueing again.

This is a list of useful things to have in the medical kit. Of course, if someone on board has special needs due to allergies or existing medical conditions you should consider these when making your provisions. Always keep in mind that there are no hospitals near by and the few that you can get to probably don't have the medicine you need.