Older cattle frequently have been exposed to the parasites and developed a degree of immunity. Adult worms in the gut of cattle produce eggs that are passed in the feces. The eggs hatch, producing ...

Mexico’s chief veterinary officer said they discovered the screwworm in a cow at an inspection checkpoint close to the border with Guatemala.

“Faecal worm egg counts of above 250 eggs per gram of faeces ... as biological vacuum cleaners. Equine worms don’t develop into adults in sheep and cattle, so they won’t be harmed and ...