Jeez. Rambo, I hope that's not you in that picture!:-) Seriously, looks like someone who has a bad case of diarrhea and has just shat in his pants. For something that severe, mechanically remove as much of the accumulated poo as possible (do this over or into the toilet), then wash in lukewarm water to remove the ground-in poo, then wash in boiling water if bleach is not available.
Re. boiling water: As it turns out, this is a viable method for dealing with hazardous cases such as diapers and poopy pants. Get a large pot that is used for no other purpose. Preferably have the fire for this located outdoors so the potentially stinky steam isn't in the house. Drop the affected clothes into the pot and boil for 10 to 30 minutes. Websearch the term "wash boiler" for more information. Folks from Australia who are reading this might know more about this subject since wash boilers were more common there as late as the 1970s.
One thing that could be helpful for dealing with poo: websearch for "Wonder Wash." This little contraption looks like a large cookie jar mounted in a frame with a crank, and costs about $50. You put the poopy pants in, add hot water and detergent, and turn the crank for 60 to 180 revolutions. The point being, it's tolerant of boiling water, and it's a relatively small container, and it's smooth inside so it can be cleaned after use. So you can use it for dealing with small quantities of poopy pants and suchlike, without having to put them in your regular washer and either use a lot more hot water or potentially spread residual contamination around to the interior of the washer where it could get into subsequent loads at lower temperatures.
You do not want to spread Norovirus or E.Coli around your family, household, or community, unless you enjoy the prospect of explosive diarrhea and projectile vomiting for 2 to 5 days, with potential risk of dehydration and death.
Re. body odors: Healthy sweat is one thing and I see no reason to be uptight about it. Unhealthy odors of various kinds are another entirely; they are a sign of something hazardous going on (e.g. fungus, poo, etc.). One way to prevent the latter is to wash your body carefully. For example a little soap on your hands and then wash between your toes, to prevent athlete's foot fungus. Similarly for between your legs, front & back, and under your arms. Rinse your hands between washing the different areas so as to not "mix ecosystems" between them (start with your under-arms, then do the areas between your legs, then feet last of all; i.e. start at the top and work your way to the bottom since the water in the shower will rinse each area in that order). Once again, hunter-gatherers to the rescue here: people who live like traditional Indians tend to stay naturally cleaner, and this is not a bunch of politically correct BS, I have seen it in practice.
In general: We take hygiene for granted. However, sanitation saves lives. In an age when antibiotic resistant bacteria is becoming a serious threat, prevention is more important than ever. On the other hand, in an overpopulated world, it's no tragedy when people darwinize themselves.