Microbiological diagnostics
Due to the 100% fatality rate of the infection, laboratory confirmation is most often performed post-mortem. Main methods:
- Microscopic method. Specific cytoplasmic inclusions — Negri bodies — are identified in impression smears or tissue sections of the hippocampus, cerebellum (Purkinje cells), and cerebral cortex. Romanowsky-Giemsa, Turevich, Mann, or Muromtsev stains are used for this purpose.
- Rapid diagnostics. Allows for the rapid detection of viral antigens in brain tissue or submandibular salivary glands using the direct fluorescent antibody (DFA) test.
- Biological assay. Involves intracerebral inoculation of suckling mice. The animals are observed for up to 28 days, although death usually occurs within a week. For subsequent identification of the pathogen, ELISA or the neutralization test using rabies immunoglobulin is applied.
In rare cases, antemortem diagnostics are performed in patients. Materials include skin biopsy specimens or corneal impressions (examined using the DFA test). It is also possible to isolate the pathogen from cerebrospinal fluid, tears, or saliva by inoculating mice, and to determine antibodies using CFT and ELISA methods.
Emergency prophylaxis and first aid
There is no specific treatment for rabies — only supportive care is available. Only timely prophylaxis can save the life of a bitten person. Success is due to the fact that active post-vaccination immunity manages to develop before the end of the incubation period.
Wound management tactics:
- Immediate and copious washing of the wound with soap solution.
- Antiseptic treatment of the wound edges with alcohol or iodine preparations.
- Surgical excision of the wound edges.
- Important rule: the wound must not be sutured during the first 3 days.
The biting animal (if known) is placed under mandatory veterinary observation for 10 days to rule out or confirm the presence of rabies.
Vaccination (specific prophylaxis)
Specific immunoprophylaxis is divided into preventive (pre-exposure, indicated for veterinarians, dog handlers) and prophylactic (post-exposure, performed after a bite).
- Vaccines. Today, cultured inactivated preparations are used (the virus is killed by UV or gamma irradiation). Genetically engineered vaccines containing glycoprotein G are also under development. Administration of the vaccine stimulates cellular immunity, antibody production, and interferons.
- Passive immunization. In cases of severe injuries or multiple bites, immediate protection is required. In such situations, rabies immunoglobulin is administered, which creates passive immunity protecting the patient until the production of their own antibodies in response to vaccination.
Historically, the first rabies vaccine was created by Louis Pasteur in 1885. He obtained the so-called "fixed" virus through 133 consecutive passages of the "street" virus through rabbit brain. The pathogen lost its virulence for humans, and its incubation period was reduced to 7 days. For attenuation, the spinal cords of infected rabbits were dried over caustic potash.
Briefly: answers to topical questions
What are the strict indications for passive immunization with rabies immunoglobulin?
Strict indications for passive immunization with rabies immunoglobulin are severe injuries and the threat of a disease with a short incubation period. These include:
- Dangerous localization — bites in heavily innervated areas (head, face, neck, hands, fingertips, perineum, genitals).
- Severe wounds — multiple, deep lacerations, transdermal bites, or scratches with bleeding.
- Saliva contact — any saliva contact with mucous membranes or damaged skin.
- Special exposures — injuries inflicted by wild carnivores, farm animals, bats, and rodents.
What are the main differences between the "fixed" rabies virus and the wild "street" virus?
The main differences lie in the altered incubation period and the loss of virulence after multiple passages.
| Sign | "Street" virus | "Fixed" virus |
|---|---|---|
| Incubation period | Original | Reduced to 7 days |
| Virulence | Original | Lost for species other than rabbits |
| Obtained by | Original wild strain | Sequential passage through rabbit brain (133 passages) |
According to what schedule (on which days) is the vaccine administered during emergency post-exposure rabies prophylaxis?
For emergency post-exposure rabies prophylaxis, a strict schedule of six intramuscular injections is used. The vaccine is administered at a dose of 1.0 ml on the following days after exposure:
- Day 0 — first injection;
- Day 3;
- Day 7;
- Day 14;
- Day 30;
- Day 90 — booster dose.
The course is terminated early (after the third injection) if the animal remains healthy during the 10-day observation period or if laboratory tests prove the absence of rabies.
What specific commercial rabies vaccine products are used in medical practice?
The provided materials mention one specific product for specific rabies prophylaxis:
- COCAV — Concentrated Purified Culture Inactivated Rabies Vaccine.
The preparation is administered intramuscularly; the vaccine can be used independently or as part of combination treatment together with rabies immunoglobulin.
To memorize the localization of Negri bodies: "Brain, Cortex, Hippocampus" — BCH (Cerebellum [Purkinje cells], Cerebral Cortex, Hippocampus).
Class and exam questions
The disease is invariably fatal once clinical symptoms develop. Antemortem diagnosis is difficult, and the primary confirmatory sign (Negri bodies) is detected in brain tissues.
The disease is invariably fatal once clinical symptoms develop. Antemortem diagnosis is difficult, and the primary confirmatory sign (Negri bodies) is most reliably detected in brain tissues.
What is the rationale behind post-exposure prophylaxis?
This is the administration of the rabies vaccine (and, in severe bites, immunoglobulin as well) after contact with the source of infection. Protection manages to develop due to the long incubation period of the virus.
How many days should the biting animal be observed?
Animal observation continues for exactly 10 days.
Why is the wound left open during the first days?
During the first 3 days after the bite, surgical sutures are not applied to reduce the risk of infection developing in a closed cavity and to ensure the outflow of discharge.
What else to study on this topic
- Mechanisms of cellular immunity development during vaccination
- Differences between the "fixed" Pasteur virus and the "street" strain
- The role of glycoprotein G in the development of recombinant vaccines
- Features of staining methods for Babes–Negri bodies (Turevich, Muromtsev)
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