Situation: A 29-year-old woman has a pre-employment medical examination at a private manufacturing company. Her hepatitis B surface antigen (HBsAg) test is positive. Her alanine aminotransferase (ALT) level is normal, she has no symptoms, and she recalls no past illness with jaundice. The occupational health nurse counsels her. Which instruction should the nurse give her to prevent spread of the infection to others in her home?

Hepatitis B spreads through blood, sexual contact, and from mother to child at birth. Razors and toothbrushes can carry small amounts of blood, so they must not be shared; cuts should be covered. Sharing dishes, laundry, and food preparation do not spread the virus.

Core concept: Modes of hepatitis B transmission

Hepatitis B virus (HBV) is a blood-borne pathogen. The virus is present in high concentrations in blood and serous fluids, and in lower concentrations in semen, vaginal secretions, and saliva. Transmission occurs through percutaneous or mucosal exposure to infected blood or body fluids. In the household setting, the practical question is which everyday objects or activities can actually serve as vehicles for blood-to-blood or blood-to-mucosa contact.

HBsAg positivity with a normal ALT and no symptoms describes a chronic carrier state without active hepatic inflammation. This person remains infectious to others, so counseling must focus on realistic routes of spread.

HBV is not transmitted through shared eating utensils, shared laundry, or food preparation. The virus is not spread by the fecal-oral route, respiratory droplets, or casual contact. It requires direct exposure to blood or certain body fluids. This is why hepatitis A and hepatitis E, which are transmitted through contaminated food and water, require different precautions than hepatitis B.

Key point! The distinguishing feature of HBV household precautions is preventing contact with blood, not preventing contact with saliva on dishes or clothing.

Why razors and toothbrushes are the critical items

Razors and toothbrushes are the two household items most likely to carry invisible traces of blood. A razor can nick the skin during shaving, leaving blood on the blade. A toothbrush can cause minor gingival bleeding, especially in someone with gingivitis or vigorous brushing habits. If another household member uses that same razor or toothbrush and has a small cut, abrasion, or mucosal break, the infected blood can enter their body.

Sharing razors or toothbrushes creates a direct route for blood-to-blood transmission, which is the primary mechanism of HBV spread within households. This is consistent with evidence that household contacts of chronic HBV carriers have elevated rates of infection. In one study of family members of chronic carriers, serological markers of HBV infection were commonly found among household contacts, supporting the concept that close, repeated contact within a home facilitates transmission when blood exposure occurs ^[2]. Another study among spouses of reported HBV cases found an HBsAg positivity rate of 11.80%, demonstrating that intimate household contacts carry a meaningful risk of acquiring the infection .

Why the other options are incorrect

Option	Why it is not required	Mechanism of HBV spread
1. Separate plates and utensils	HBV is not transmitted through saliva on eating surfaces in any clinically meaningful way	Not a fecal-oral or foodborne virus; requires blood or sexual contact
2. Separate laundry	HBV does not survive and transmit through routine clothing or fabric contact	No blood-to-skin transmission through dry clothing; standard washing is sufficient
3. Face mask during food preparation	HBV is not spread by respiratory droplets or airborne particles	No respiratory transmission route; masks are for droplet or airborne precautions
4. Do not share razors or toothbrushes	Correct instruction	Direct blood-to-blood contact through contaminated personal care items

Watch out! Do not confuse hepatitis B precautions with hepatitis A precautions. Hepatitis A is spread through contaminated food, water, and poor hand hygiene, so separate utensils and careful food handling matter for hepatitis A. Hepatitis B requires blood and body fluid precautions only.

Additional household precautions that follow the same principle

Beyond razors and toothbrushes, the same blood-exposure logic applies to other personal items. Nail clippers, scissors used for personal grooming, and any item that could break the skin should not be shared. Any open cuts or wounds on the carrier should be covered with a bandage. If blood spills occur on household surfaces, they should be cleaned with a dilute bleach solution while wearing gloves. These measures all address the same core concept: preventing another person’s broken skin or mucous membrane from contacting the carrier’s blood.

Counseling context for the occupational health nurse

This is a pre-employment examination finding, not an acute illness. The woman is asymptomatic with a normal ALT, so the nurse’s role is education and prevention rather than treatment. The nurse should explain that the positive HBsAg means she carries the virus and can transmit it, but that transmission requires blood or sexual exposure. Household members should be tested for HBV markers and offered vaccination if they are not immune. Vaccination of susceptible household contacts is the most effective long-term strategy to prevent intra-familial transmission .

The instruction to avoid sharing razors and toothbrushes is the only option that directly interrupts the blood-to-blood transmission route of HBV in the home. The other options target transmission routes that HBV does not use.