A weakly positive HFMD antibody suggests that you may have been infected with a virus related to oral HFMD or have received the HFMD vaccine. HFMD is a common summer infection that is most likely to occur in children under the age of 5 and is highly contagious. The source of infection is the child with HFMD. Many children first develop a fever, and after the fever ends, herpes on the hands, feet, and mouth will appear. Herpes and skin rashes usually go away on their own in 2-3 days, and will not leave any scars or hyperpigmentation.