In everyday practice, the emergency physician has the difficult task of diagnosing and managing contagious disease. When a patient presents with a communicable disease, the physician’s immediate obligation is to attend to that individual's needs. However, the physician must also consider the extent in which the communicable disease may spread and who may be subsequently affected.

Actions have alleged that a doctor was liable to a third party for failure to diagnose the disease in a patient, for failure to inform a third party of the contagious nature of the disease, for negligently advising a third party that there was no danger of infection, or for failure to prevent the spread of the disease to the third party.

For example, in the case of DiMarco v. Lynch Homes the Supreme Court of Pennsylvania held that a physician had a duty and could be liable to a patient's sexual partner for failing to properly warn the patient about transmission of a hepatitis B. The patient’s boyfriend claimed that the defendant physicians were negligent for not warning the patient that having sexual relations within six months of the exposure could cause her sexual partner to contract hepatitis.

Although infectious disease experts may disagree over the time frame during which the disease can be transmitted, the point is that Pennsylvania has now created a duty to warn third parties when hepatitis is diagnosed. It is anybody's guess whether the Pennsylvania courts will limit this to the attending physician, based on the facts of the DiMarco case, or would be willing to extend the duty into the emergency department.

There may be a ‘duty to warn’ following an exposure to a patient with meningococcal meningitis. Although there is no case law on point, the emergency physician diagnosing meningococcal meningitis may have a duty to warn the emergency department staff, family, classmates, etc. regarding the potential danger of exposure, and about recommendations for prophylaxis.

Emergency physicians taking care of known HIV positive patients may have an obligation to warn emergency department and other staff of the potential danger of exposure. Some state laws create a duty to warn third parties who may be in immediate danger from exposure to a patient with HIV who refuses to communicate the diagnosis. In other states there is a strict duty not to communicate HIV related information. Statutes and regulations vary from state to state. The EP should contact hospital or local counsel regarding the nature of the duty to report and the obligation to third parties as it relates to patients infected with HIV.

There are cases from several jurisdictions related to transmission of hepatitis, herpes and other sexually transmitted diseases. Although most states have formal reporting systems for these conditions, the emergency physician would be wise to warn the patient about the dangers of transmission, or to refrain from contact until the private physician has had an opportunity to obtain culture results and review these issues.