When we think of international travel hazards, thoughts drift to Montezuma's revenge and terrorism. Yet, another danger lurks beyond our boundaries. Whereas 10 percent of cancers in the US are caused by infection, that number increases to 25 percent worldwide. Many of these potentially cancer-causing infections can be avoided through knowledge and vigilance. A few to be aware of while enjoying your international adventures:
1. Schistosomiasis - bladder cancer due to the parasitic infection, schistosomiasis, is the leading cause of death in men aged 20 to 44 in Egypt. Schistosomiasis is an infection spread through snails in fresh water. The parasites can penetrate through unbroken skin, and cause chronic inflammation in the bladder that can lead to cancer. Regions where this is found include the Nile River valley in Egypt, Lake Malawi in Africa, as well as certain regions in Southeast Asia, Southern China, Northern South America, the Middle East, and the Caribbean. The parasites are not found in the ocean, and chlorinated water is considered safe.
2. Liver flukes - commonly found in East Asia and especially northeast Thailand, are a significant cause of bile duct cancer. Liver flukes are contracted by eating raw or undercooked freshwater fish that have been contaminated by the parasite. Avoid freshwater sushi when traveling in these regions.
3. H.pylori - infection with the bacteria H.pylori is considered the leading cause of gastric cancer. Gastric cancer has been declining in the US, but remains the fourth most common form of cancer worldwide. It is acquired through person to person contact and ingesting contaminated water and food. When traveling, choose water sources that have been treated with chlorine (and then filtered when possible) or "safe" bottled water. If you develop symptoms of peptic ulcer disease (80-90 percent of cases are due to H.pylori,) consult your health care provider.
4. Hepatitis B - is the leading cause of liver cancer worldwide, responsible for roughly 80 percent of cases. While many cases are sexually transmitted, often the source of transmission is unknown. It is much more contagious than HIV, and can be transmitted even by sharing a toothbrush. Consider immunization, and take precautions around any sources of blood products - even toothbrushes.
5. HIV - is well known for the cancers it can lead to - and its rising incidence, especially in Africa. Before traveling, and travel to Africa in particular, review "universal precautions" on the CDC website listed below.
6. HTLV-1 - Human T cell lymphotrophic virus (HTLV) is a virus rarely found in the US, but infects an estimated 15 to 20 million people worldwide. Of these, roughly 2 to 5 percent will develop adult T cell leukemia/lymphoma. HTLV-1 is most commonly found in Japan, but also occurs in parts of South America, the Caribbean, Papua New Guinea, and central and west Africa. The infection is transmitted through blood, sexually, and from mother to child through breastfeeding.
If you plan to travel internationally, check out the CDC's website to see what infections are endemic in that region and precautions to take. Here at home, as many are keenly aware of with the advent of the HPV vaccine, infections can predispose to cancer as well. Of the 10 percent of cancers in the US caused by infection, a significant number are related to sexually acquired infections. Practice safe sex wherever you are!
For further information on cancer prevention, visit our web site, or read "Avoiding Cancer One Day At A Time: Practical Advice for Preventing Cancer."
