#!/bin/bash
s='id,name,continent
1,Louise,Latin America
2,Sasha,Asia
3,Mike,North America'
rx='^[0-9]*,[^,]*,[[:alpha:][:space:]]*$'
while read -r line; do
  if [[ "$line" =~ $rx ]]; then
      echo "$line: Valid"
  else
      echo "$line: Invalid"
  fi
done <<< "$s"