March
For an overview of all updates made to the Communicable Disease Control Manual, refer to Updates to the Communicable Disease Control Manual – Health New Zealand | Te Whatu Ora .
Rabies virus is a species of the genus Lyssavirus of the family Rhabdoviridae.[1] (external link) Seven lyssaviruses, all antigenically related, are now recognised: rabies and six rabies-related viruses, five of which are known to have caused fatal infection in humans. The differences are often associated with geographic location and mammalian species. Some of these rabies-like illnesses will be diagnosed as rabies using the standard (FA) test.
Currently only Rabies is listed in the notifiable infectious diseases schedule. Reporting of other lyssavirus infections by medical practitioners is recommended with informed patient consent.[2] (external link)
New Zealand has long been rabies free. Rabies and other lyssaviruses are, however, widely distributed throughout the developed and developing world, including Asia and some parts of Oceania, and cases in New Zealand could potentially occur in people who have travelled through rural parts of rabies-endemic countries.
Highly variable, usually 3–8 weeks (but may be as short as 9 days or up to 7 years).
Lyssaviruses are carried in the saliva of infected mammals and transmitted by percutaneous introduction through a bite or scratch into a fresh break in the skin or by contact with intact mucous membranes (eyes, nose, mouth) (Communicable Diseases Prevention and Control Unit 2008; BCCDC 2009). Transmission has also occurred through transplantation of organs (usually cornea; also liver, kidneys, vascular) taken from people who died with undiagnosed rabies. There have been rare reports of transmission by aerolisation of infectious material – in a laboratory setting and in a bat-infested cave.
From dogs and cats: For 3–7 days before onset of clinical signs and throughout illness. Bats and skunks may shed the virus for 1–2 weeks before onset of disease. It remains unclear as to whether it is possible for animals in the wild to carry lyssaviruses asymptomatically.
Confirmed: A person who has a clinically compatible illness and has laboratory definitive evidence.
Probable: A person who has a clinically compatible illness and has a history of travel to an area where rabies is endemic.
Under investigation: A person who has been notified to the medical officer of health, but information is not yet available to classify them further.
Not a case: A person who has been investigated and subsequently found not to meet the case definition.
An acute encephalomyelitis that progresses to coma and death, typically within 10 days of symptom onset.
There are no epidemiological criteria for rabies.
Detection of lyssavirus nucleic acid by polymerase chain reaction testing.
OR
Detection of rabies neutralising antibody at a titre of at least 1:5 in serum or cerebrospinal fluid (provided the individual is not vaccinated).
OR
Rabies IgG seroconversion in someone who has not been vaccinated.
Refer to Appendix 4: Direct laboratory notification of communicable diseases flowcharts for the direct laboratory notification process for Rabies and other lyssaviruses.
Testing may be carried out for the following reasons.
Health practitioners should promptly notify the local medical officer of health of suspected cases. Notification should not await confirmation.
If rabies is suspected, the following information should be obtained and included on the laboratory test request form.
Polymerase chain reaction (PCR) is the primary diagnostic tool. Laboratory confirmation requires detection of lyssavirus nucleic acid to confirm rabies.
Refer to laboratory criteria and case classifications for confirmed and probable case definitions.
| Test | Sample | Timing of sample collection | Specific guidance |
| Polymerase chain reaction (PCR) |
|
On clinical presentation | If collected very early in disease onset, PCR tests may be negative; repeat samples may be required. |
| Serology |
Serum |
Within 2 weeks of symptom onset. | Measure rabies IgG during early clinical presentation, then repeat 1 to 2 weeks later to assess for IgG seroconversion. |
Polymerase chain reaction (PCR) testing is used to detect rabies virus genetic material. This test is not available in Aotearoa New Zealand and must be referred to Victorian Infectious Disease Reference laboratory after discussing with the on-call clinical virologist.
If another lyssavirus infection is suspected, discuss testing with PHF Science; the laboratory methods used are the same as those for rabies.
Serum antibody testing is primarily used to assess immune status, particularly for individuals at occupational risk (e.g. veterinarians and laboratory workers). It is not typically useful for diagnosing clinical rabies, as diagnosis relies on detecting viral ribonucleic acid or antigens in nervous tissue.
Rabies IgG enzyme immunoassay (EIA) is available at Awanui Labs and can be a useful adjunct test to rapidly establish a suspected case’s IgG status.
The Rapid Fluorescent Focus Inhibition Test is the recommended method for measuring rabies virus-neutralising antibodies. An antibody level of 0.5 IU/mL or greater is considered indicative of protective immunity, consistent with World Health Organization and U.S. Centres for Disease Control and Prevention (external link) guidelines.
Antibodies can be detected within 2 weeks of symptom onset in most individuals with clinical rabies. Significantly higher titres are seen in individuals with clinical rabies compared with vaccinated individuals. High cerebrospinal fluid antibody titres are a hallmark of clinical rabies and do not occur following vaccination.
Attending medical practitioners or laboratories must immediately notify a medical officer of health of suspected cases of rabies. Notification should not await confirmation.
Other lyssavirus infections are not currently listed on the notifiable infectious diseases schedule. Reporting of other lyssavirus infections by medical practitioners is recommended with informed patient consent.[3] (external link)
The Ministry of Health reports to the World Health Organization (WHO) where appropriate, in accordance with the International Health Regulations (2005).
See Appendix 5: Escalation pathways for more information
Obtain a history of travel, vaccination and animal bites.
Ensure laboratory confirmation has been attempted.
Given the lack of evidence for person-to-person transmission of rabies (other than through corneal or solid organ transplantation), in 2008 the Centers for Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee recommended that medical staff adhere to standard infection control precautions. Staff should wear gowns, goggles, masks and gloves, particularly during intubation and suctioning.
Post-exposure prophylaxis is only indicated when a contact has been bitten by a case. It is also indicated when the case’s saliva or other potentially infectious material such as neural tissue has contaminated an open wound or mucous membrane (CDC 2008).
The case should be under the care of an infectious diseases physician.
Advise the case and their caregivers of the nature of the infection and its mode of transmission.
All those who have an open wound or mucous membrane exposure to the case’s saliva.
All contacts bitten or scratched by, or with wound or mucous membrane exposure to, the same rabid animal.
Nil.
Human disease caused by all known lyssaviruses, including Australian bat lyssavirus (ABL), may be prevented by initial first aid and specific treatment with rabies immunoglobulin (RIG) and vaccination.
Test any contact animal for the virus if possible.
Consult an infectious diseases physician for advice.
Advise all contacts of the incubation period and typical symptoms of rabies. Encourage them to seek early medical attention if symptoms develop.
Attempt to identify the animal source so steps may be taken to minimise the risk of further transmission.
Clean and disinfect surfaces and articles soiled with saliva.
Pre-exposure prophylaxis rabies vaccination may be indicated for people travelling to rabies-endemic countries and who plan to be in contact with wild or domestic animals, visiting remote areas where medical care is difficult or staying longer than 1 month in an area where dog rabies is common. It is also recommended for research laboratory personnel working with live lyssaviruses.
Advise people travelling in a country with endemic rabies that, if they sustain an animal bite, they should wash the wound immediately and thoroughly with soap and water and then be assessed by a doctor as soon as possible to determine the need for post-exposure prophylaxis. Advise travellers they should obtain detailed, written information on the type of any immunoglobulin and/or vaccine they have received and the schedule.
Ensure complete case information is entered into EpiSurv (external link).
On receiving a notification, medical officers of health should immediately notify the national protection clinical team (use Appendix 5: Escalation pathways for pathways for notification for awareness, or for escalation).
If the case may have acquired rabies in New Zealand, Health New Zealand will notify the appropriate staff in the Ministry for Primary Industries, on phone: 0800 809 966, so that further investigation of the source can be undertaken.
If the case has been acquired in another country, obtain as much information as possible about the case’s contacts in that country as it may be necessary to inform health authorities in that country. Such liaison with other countries will be conducted by the Health New Zealand.
[1] Unless otherwise specified, the term ‘rabies’ in this chapter can be read as ‘rabies and other lyssaviruses’.
[2] In this case, informed consent includes understanding and agreement by the patient that their name and some details will be provided by the responsible medical practitioner to the local medical officer of health for public health follow-up and inclusion in national infectious disease statistics.
[3] In this case, informed consent includes understanding and agreement by the patient that their name and some details will be provided by the responsible medical practitioner to the local medical officer of health for public health follow-up and inclusion in national infectious disease statistics.