Situation: After a typhoon flooded a low-lying barangay, the nurse at the Rural Health Unit (RHU), which also serves as an animal bite treatment center (ABTC), sees clients with animal bites and flood-related illness. Four residents come to the animal bite treatment center (ABTC) on the same morning after contact with stray dogs today. None of them has ever received rabies vaccine, and none of the dogs can be found for observation. According to DOH guidelines, which resident needs rabies immune globulin (RIG) in addition to the vaccine?

A lick on broken skin or mucous membranes is a category III exposure, because saliva reaches tissue through the break; it needs vaccine plus RIG. Nibbling of uncovered skin and minor scratches without bleeding are category II (vaccine only). The DOH rule that manages category II as category III applies to the head and neck, not the hands. A lick on intact skin is category I and needs no post-exposure prophylaxis.

Category of exposure determines whether RIG is added
Rabies post-exposure prophylaxis (PEP) is decided by the WHO exposure category, which classifies contact based on whether saliva reaches broken skin, mucous membranes, or intact skin. Category III exposures require both rabies vaccine and rabies immune globulin (RIG), because the virus may already be present in tissue before vaccine-induced antibodies appear. RIG provides immediate passive immunity at the wound site while the vaccine series builds active immunity over 7–14 days ^[2][3].

Why a lick on a fresh abrasion is category III
A fresh abrasion means the epidermis is disrupted. When a rabid dog licks that area, saliva carrying rabies virus can directly enter through the break in the skin, which is functionally equivalent to a bite that breaks the skin. The virus travels along peripheral nerves toward the central nervous system, and once clinical signs appear, the infection is nearly 100% fatal ^[2]. Because the incubation period can be shorter than the time needed for vaccine-induced antibody production, RIG must be infiltrated into and around the wound to neutralize virus immediately ^[2][3].

Comparing the four residents

Resident	Exposure description	WHO category	PEP needed
9-year-old	Lick on intact forearm skin	Category I	No PEP; wash skin only
12-year-old	Non-bleeding scratch on back of hand	Category II	Vaccine only
40-year-old	Lick on fresh abrasion	Category III	Vaccine plus RIG
30-year-old	Nibbling of bare calf, no skin break	Category II	Vaccine only

Why the hand scratch and calf nibble do not require RIG
A non-bleeding scratch and nibbling of uncovered skin without a break are both category II exposures. In these cases, the virus has not been introduced through a full-thickness skin defect, so vaccine alone is sufficient to generate protective antibodies before the virus reaches the CNS . Key point! The DOH provision that upgrades category II to category III applies only to head and neck exposures, not to the hand or calf. The hand is not a special site under this rule.

Why intact skin licking needs no PEP
Intact skin is an effective barrier against rabies virus. A lick on unbroken skin is category I and requires only washing of the exposed area; no vaccine or RIG is indicated . Watch out! If the same lick occurred on mucous membranes such as the mouth, eyes, or genital area, it would be category III even without visible bleeding, because mucous membranes are not keratinized and permit viral entry ^[3].

Clinical reasoning for the correct answer
The 40-year-old with a fresh abrasion licked by a stray dog is the only resident whose exposure crosses into category III, because the broken skin provides a portal for saliva-borne virus. The 9-year-old has intact skin (category I), while the 12-year-old and 30-year-old have category II exposures that require vaccine only. Since none of the dogs can be observed and none of the residents has prior vaccination, the category III resident must receive RIG infiltrated around the abrasion in addition to the first vaccine dose ^[2][3].