I see there is no trouble when traveling in Cambodia but you should pay attention to some related health and safety issues.
Cambodia is a safe and friendly country, with the usual exception for large cities late at night, particularly Phnom Penh, and unobserved luggage or wallets. Bag snatching, even from those on bicycles and motorcycles, is a problem in Phnom Penh. Be discreet with your possessions, especially cash and cameras, and as always, take extra care in all poorly lit or more remote areas.
Most medical services in Cambodia are not up to Western standards, and the rest are few and far between and very expensive. Should you become seriously ill or injured while in Cambodia, evacuation to Thailand or Singapore will be the most likely result. Because this can be incredibly costly, adequate insurance coverage is an absolute must while in Cambodia.
There are presently no vaccination requirements to enter Cambodia, unless arriving directly from Africa. Border officials have from time to time operated scams whereby travellers were "fined" for not having proof of vaccinations, however this now appears to have stopped completely.
Before visiting Cambodia, be sure to discuss prevention with a qualified specialist / travel clinic. It's especially important to review the relevant vaccinations (hepatitis A, hepatitis B, Japanese encephalitis, measles, rabies, tetanus-diphtheria, typhoid, etc) well in advance; in addition, both malaria and dengue fever are endemic in some parts of Cambodia, particularly in heavily forested areas for malaria, though dengue fever can be found throughout the country.
HIV/AIDS is widespread and on the increase, with some surveys showing as many as 40% of commercial sex workers being HIV positive. If you intend to engage in such activities, be sure to use protection.
Tap water in Cambodia is not suitable for drinking. Phnom Penh municipality claims that its water is treated and cleaned and this is probably true; however by the time it gets to your tap, it's most likely been contaminated anyway. Bottled water is the only thing you should ever drink or brush your teeth with. Be careful with ice in your drinks, as it has often also come from the tap out the back.