Rabies Testing in Humans
The purpose of testing living patients for rabies is not to determine a course of treatment, but to confirm the need for the extraordinary measures required to keep the number of health care workers requiring post-exposure prophylaxis to a minimum, and to determine whether post-exposure prophylaxis should be started on those already exposed. Specimen submission must be done in accordance with the Centers for Disease Control (CDC) protocol, and the CDC's patient information form must be completed and included with the specimen.
This document should be used as a tool to assist attending physicians in making the determination whether human rabies testing is required in a particular case. The Rabies Division at CDC confirms that in most instances, rabies can be ruled out as the result of answering a few simple questions rather than by specimen testing.
- What is the date of onset? The length that symptoms have been present can actually be used to rule out rabies. Rabies infection is very unlikely in a patient who has an extended duration of illness.
- Is the patient comatose/intubated? Most patients with rabies infections will lapse into coma and life support is required within a short period of time. If a patient has been placed on life support and then recovered enough for it to be removed, rabies can be ruled out. Likewise it can be ruled out on a patient on life support whose condition has not progressively worsened.
- Has the patient's condition improved? With many conditions, improvements and relapses are fairly common. This is not so with rabies, as the course of the disease is relentlessly downhill. Once symptoms begin, the patient will steadily deteriorate until death. Rabies can be ruled out in patients whose conditions improve.
- Has limited access to the patient been established? If the facility has not yet instituted these precautions, why does the physician feel that rabies should be high on the list of differential diagnoses? Additionally, if the physician does feel that rabies is a valid possibility, these precautions need to be taken immediately.
- Is there a history of animal exposure? If the answer is no, or if the information has not been collected, why is rabies being considered?
- Is there a history of drug abuse, alcoholism or chemical exposure? Many times physicians have not considered drug abuse, alcoholism, or possible pesticide (or other chemical) exposure as a possible etiology.
If antemortem specimens are going to be submitted, call the Texas Department of State Health Services (DSHS), Zoonosis Control Group (ZCG), at (512) 776-7255 to obtain the latest copy of CDC's protocol and patient information form. This form must be used if specimens are going to be submitted to CDC.
Postmortem testing is also available through CDC. If specimens for either antemortem or postmortem rabies testing are going to be submitted to CDC, call the Texas Department of State Health Services (DSHS), Zoonosis Control Branch (ZCB), at (512) 776-7255 to obtain the latest copy of CDC's protocol and patient information form. This form must be used if specimens are going to be submitted to CDC.