Hepatitis B

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Organism, Causative Agent, or Etiologic Agent
Hepatitis B infections are caused by the Hepatitis B virus (HBV) which is a hepadnavirus. 

Transmission
HBV is transmitted through activities that involve percutaneous (i.e., puncture through the skin) or mucosal contact with infectious blood or body fluids (e.g., semen, saliva), including

• Sex with an infected partner
• Injection drug use that involves sharing needles, syringes, or drug-preparation equipment
• Being born to an infected mother
• Contact with blood or open sores of an infected person
• Needle sticks or sharp instrument exposures 
• Sharing items such as razors or toothbrushes with an infected person 

HBV is not spread through food or water, sharing eating utensils, breastfeeding, hugging, kissing, hand holding, coughing, or sneezing.

Symptoms (Clinical Illness)
The presence of signs and symptoms varies by age. Most children under age 5 years and newly infected immunosuppressed adults are asymptomatic; whereas 30%–50% of persons aged ≥5 years have initial signs and symptoms. When present, signs and symptoms can include

• Fever
• Fatigue
• Loss of appetite
• Nausea
• Vomiting
• Abdominal pain
• Dark urine
• Clay-colored bowel movements
• Joint pain
• Jaundice (yellowish skin or eyes)

There are two stages to hepatitis B: acute and chronic. At the time of infection with hepatitis B, people are considered to have acute hepatitis B. After that, their hepatitis B will resolve, making them immune to further infection or they will become chronically infected, meaning they can infect other people and may continue to have other symptoms or complications. After acute infection, about 90% of infants and 30% of children under 5 years will become chronically infected compared to about 5% of adults.

Persons with chronic HBV infection might be asymptomatic, have no evidence of liver disease, or have a spectrum of disease ranging from chronic hepatitis to cirrhosis or hepatocellular carcinoma (a type of liver cancer).

Incubation Period
The incubation period is 45–180 days with an average of 60–90 days.

Communicability
The blood of infected persons is infective many weeks before the onset of symptoms and remains infective through the acute clinical course of the disease and during the chronic carrier state, which may persist for life. The younger a person is when infected, the more likely it is he or she will become chronic disease carriers. Additionally, persons who are hepatitis B e antigen (HBeAg, also referred to as “little e antigen”) positive are highly infectious. 

Prevention and Vaccination
To prevent infection, Texas recommends the vaccination of all children at birth. Vaccination is currently required for school entry in Texas. Adults that are at high risk for infection can also be immunized. Among others, this includes health care workers and people who use drugs or have unsafe sexual practices. In addition to vaccination, practicing safe sex and not sharing needles or other instruments that might be exposed to bodily fluids can reduce the risk of spreading hepatitis B.

Pregnant women are routinely screened during prenatal care and at birth to ensure that hepatitis B is not passed to their baby. If a woman has hepatitis B, her baby will receive preventive medication at birth to help prevent infection. Texas DSHS has a Perinatal Hepatitis B Program who work alongside public and private healthcare providers and coalitions to prevent perinatal hepatitis B transmission.

School Exclusion Policy
Children with acute or chronic hepatitis B do not need to be excluded from school or childcare. Rules for exclusion of sick children from school and childcare are outlined in the Texas Administrative Code, specifically Rule 97.7 for schools.

Recent Texas Trends
Since 1991, Texas has experienced a steady decline in the incidence of acute hepatitis B. Currently only acute hepatitis B is reportable in Texas. Over the past 10 years, the reported incidence for acute hepatitis B has continued to decline, from 394 cases in 2010 to 50 cases in 2020. Adults ages 18 and older have consistently made up the majority of acute hepatitis B cases in Texas.