Rabies is fatal, but preventable – Be proactive.
Johannesburg, 10 October 2019. Between 5 and 30 human rabies cases are confirmed in South Africa every year and more than 70% of these occur in children and teenagers.[1] The rabies virus is transmitted through the saliva of a rabid animal to other animals or humans.[1] In SA, almost all human rabies cases are related to exposure to an infected domestic dog.[1] Other reservoir species include the bat-eared fox, black-backed jackal and yellow mongoose, and cases of rabies have also been reported in several livestock species, including goats, cattle, sheep and horses, but these latter animals act as dead-end hosts and contact with them is unlikely to infect people.[1] Humans are also incidental dead-end hosts of the infection and human-to-human transmission is unlikely.[1]
Rabies is almost always fatal following the onset of clinical symptoms.[2]Although timeous post-exposure prophylaxis (PEP) is 100% effective in preventing rabies, it is unnecessary in those who have received pre-exposure vaccination against the rabies virus.[1],[2]
The virus may enter the body wherever saliva comes into contact with broken skin or mucosa, so wounds do not have to be large and potentially any contact of the virus with broken skin or mucosa should be considered a risk for exposure.[1] After infection, there is usually a 20-90 day incubation period followed by a short prodrome of nonspecific symptoms (e.g., fever, pain or paraesthesia at the wound site).[1] An acute encephalitis phase follows with death within one to two weeks.[1] The acute phase may take one of two forms – the furious form, including hypersalivation, confusion, delirium, hallucinations, behavioural changes, aggression, intermittent and painful spasms; or a paralytic form with ascending paralysis, coma and death.[1] There is no specific effective treatment for rabies infection and management is supportive.[1]
In the event of exposure to the rabies virus, timeous post-exposure prophylaxis with administration of rabies immunoglobulin (RIG) and the rabies vaccine will prevent rabies infection.[1] However, delay in seeking PEP, improper wound care, unnoticed wounds, direct nerve inoculation and lack of patient compliance with vaccination schedules may result in failure of PEP, which is fatal.[2]
When exposure to a potentially rabid animal and the rabies virus is likely, in unvaccinated people, rabies PEP is lifesaving and must be provided.[1] The wound should be thoroughly washed with soap and water starting at home and repeated at a healthcare facility ideally with the addition of an iodine-based disinfectant or 70% ethanol.[1] The rabies vaccine should be administered to all patients, including women, children, the elderly and immunocompromised individuals.[1],[2] Vaccination during pregnancy and lactation: pre-exposure vaccination during pregnancy should only be given if clearly indicated, and following an assessment of the risks and benefits.[3] PEP in pregnancy: due to the severity of the disease, pregnancy is not a contraindication.[3] The vaccine must be administered intramuscularly into the deltoid or anterolateral thigh (in children), but not into the gluteus muscle, because this is ineffective in eliciting an immune response.[1] Doses are administered on days 0, 1, 7 and 14 or 28, so that a complete vaccination course consists of four doses in total.[1]
Because an immune response only appears 7-10 days after vaccine administration, where there is exposure resulting in any breach of the skin, or which draws any amount of blood, or where mucous membranes are exposed, rabies immunoglobulin (RIG) should be administered in addition to the vaccine.[1] It should be infiltrated directly into and around the wound to allow for rapid neutralisation of the virus.[1],[2] Additional circumstances where RIG should be administered include multiple bites, bites to highly innervated parts of the body (e.g., hands, neck, head), patients with severe immunodeficiency, and in cases where the biting animal is a confirmed or probable rabies case.[2]
Rabies is a vaccine-preventable disease in both dogs and humans.[2] Especially in endemic areas, dog owners should ensure that their pets are vaccinated as this will interrupt viral transmission at the source and prevent transmission to humans.[2] Pre-exposure vaccination is recommended for all people at high risk of exposure.[2] This includes those in living in, or travelling to, highly endemic settings and individuals at occupational risk.[2] In the event of exposure to a suspected rabid animal, two booster doses are administered (on days 0 and 1), regardless of rabies serum antibody level or perceived immunity of the patient.[1] Importantly, RIG is not indicated after exposure in people who have been previously vaccinated, because it may depress the rapid boosting of antibodies.[1],[2]
In conclusion, where timeous post-exposure prophylaxis is unavailable, rabies infection in an unvaccinated person is catastrophic.[2] The public should be encouraged to have their pets vaccinated against rabies, and where appropriate, make sure that they and their families are vaccinated against the disease as well.
References
[1] Weyer J, Blumberg L. Management of rabies. SA Fam Prac 2019;61(3):63-66.
[2] World Health Organization (WHO). Rabies vaccines: WHO position paper – April 2018. WHOWeekly Epidemiological Record 2018; 93(16): 201-220. Available at https://www.who.int/rabies/resources/who_wer9316/en . Accessed 3 September 2019.
[3] Inactivated Rabies Vaccine Package Insert. May 2016. Sanofi Pasteur.