It's probably just one of em durn parasites or a tick. Sick one of them border snakes after it. That'll get it, for sure.
Really. Right now a chicken wire cage full of rattlers on the front porch seems like a good idea.
A few points of reasoning...
I could drop all four of these people in downtown Tokyo, Seoul, Manila, Beijing, Jakarta, Bangkok, Singapore, Hanoi -- and nobody would give them a second look. Put a decent hair style on the guys and let the girls untie their hair and they would look totally different. Note the girls are wearing no cosmetics and imagine what the right touches would do to them. I know they all look young, but I place their ages in the 24-30 range.
They are coming to this country, so fairly fluent English is going to be a key to success. China and North Korea start their covert agents off at remarkably young ages, to include language training. Most filipinos are naturally fluent in English as it is the other official language, equal to Pilipino/Tagalog -- and they've had a full-blown Islamic insurgency there for well over a century.