Rabies is an acute viral infection of the nervous system that primarily affects dogs and can also be transmitted to humans. It is a zoonotic infectious disease caused by a virus. The word Rabies originated about 3000BC from the word Rabha, which means, “violence”

1. RABIES
BY
M.N.O. UWAMOSE
SEPTEMBER, 2014

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ABSTRACT
Rabies is an acute viral infection of the nervous system caused by a virus.
The virus is commonly transmitted to man through the bite of a rabid animal.
More than 3.3 billon people are at risk of rabies worldwide, with
approximately 55,000 deaths estimated per year. The incidence of Rabies
infection per year in the world is estimated at 3.3 billion to 3.6 billion with
approximately 1.74 million deaths. Rabies epidermis occurs in Asia, North and
South America, and Africa. Rabies virus is a member of the Rhabdoviridae
family (Genus: Lyssavirus). The virus travels to the brain through the
peripheral nerves causing acute encephalitis (inflammation of the brain) in
warm-blooded animals (man). Early symptoms associated with rabies
includes Malaise, headache and fever, progressing to acute pain, restlessness,
hyperactivity, uncontrolled excitement, depression, hydrophobia, etc. Rabies
can be diagnosed by isolating the virus from the patient’s saliva, throat,
corneal impression or skin. Treatment is often by injection of rabies vaccines,
antiserum, and immunoglobin. Generally, Rabies is a neglected disease of the
poor and vulnerable populations. It occurs mainly in rural communities where
measures to prevent dog to human transmission have not been implemented
and deaths are rarely reported. Educating people about the severity of the
disease and also focus on the animal reservoir will help to control the disease.

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1.0 INTRODUCTION
Rabies is an acute viral infection of the nervous system that
primarily affects dogs and can also be transmitted to
humans. It is a zoonotic infectious disease caused by a virus.
The word Rabies originated about 3000BC from the word
Rabha, which means, “violence” (Adedeji et al., 2010). It
was once known as HYDROPHOBIA. Rabies virus is a
member of the Rhabdoviridae family (Genus: Lyssavirus).
The virus is found in the salivary glands and central nervous
systems of infected warm-blooded animals (including man)
from where it travels to the brain through peripheral nerves.
This deadly viral infection causes acute encephalitis
(inflammation of the brain) in warm-blooded animals. Once
symptoms develop, rabies is usually very fatal.
The incidence of Rabies occurs worldwide with an estimated
of 3.3 billion to 3.6 billion individuals at risk of the infection
and approximately 1.74 million deaths. An estimated number
of 55,000 people die each year from Rabies, 99% of which
are from rabid dog bites. 99% of human deaths due to rabies
occurred in Asia and Africa with an estimated 31,000 and

4. 24,000 deaths respectively. Rabies epidermis occurs in Asia,
North and South America, and Africa. In 2005, more than 12
million individuals received a Post Exposure Prophylaxis
(PEP) treatment against rabies, this treatment consist of the
administration of rabies immunoglobulin. This prevented an
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estimated death of about 280,000 people (WHO 2005).
NIGERIA STATISTICS
Rabies was first reported in Nigeria in 1912 in two persons
but the first laboratory confirmation was in 1925 by
demonstration of Negri bodies in the brain smear of a mad
dog (Ekele, et al., 1984). The disease has been declared
endemic in Nigeria and it remains one of the most important
zoonoses in the country (Nawathe, 1980; Kujul, et al.,
2010).

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2.0 PROPERTIES OF THE RABIES VIRUS
Rabies is caused by a neurotropic virus of the genus
Lyssavirus, family Rhabdoviridae. The virus is a single
stranded, neurotropic, negative sense RNA virus whose
genome encodes five proteins: a Glycoprotein, a
Nucleoprotein and three other proteins – Matrix Protein,
Phosphoprotein and Polymerase.
The virus is bullet shaped and has a protein coat with a lipid
envelope. The outer surface of the virus is covered with
thumb-like glycoprotein projections that are 5-10 nm long
and 3 nm in diameter. The virus length averages
approximately 780 nm. (Albertini et al., 2006).

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3.0 TRANSMISSION
Rabies virus is zoonotic, meaning it can be transmitted from
one species to another such as from dogs to humans. Dogs
are the main host and transmitter of rabies (Suzuki K, et al.,
2008). They are the source of the infection in all of the
estimated 55,000 human rabies deaths annually in Asia and
Africa. Other sources of the infection include bats, deer,
e.t.c.
Rabies is transmitted through the bite or scratch of infected
animal (Rabid animal) which introduces the virus through the
skin. Bites cause approximately 99% of Rabies cases
worldwide (Awoyomi et al., 2007).
Transmission can also occur when infectious materials
(saliva) come in direct contact with human fresh skin
wounds, and also by kissing.
Human – human transmission of rabies is possible through
tissue (such as corneas) transplants from infected humans.
Rarely, rabies may be contracted by inhalation of virus
containing aerosol (Takayama 2005).

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4.0 PARTHENOGENESIS
Rabies infects the brain and spinal cord in the body. Rabies
infection is initiated in the victim on acquisition of the virus
through the bite or direct saliva contact with infected animal.
The virus then incubates at the site of inoculation replicating
within muscle cells. After long incubation period, the virus
enters the peripheral nerves and travels by retrograde
axonal flow toward the Central Nervous System, first to the
spinal cord then to the brain. Once in the brain, the virus
travels by axonal flow down the trigemmal nerve to the
salivary glands. The virus is found in the saliva and the
animal becomes infective 3 – 5 days depending on the onset
of clinical signs. The length of time of development of clinical
signs is related to the distance the virus must travel (Drew
2004; Beard 2001; Takayama 2005).

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5.0 SYMPTOMS
The period between infection and the first flu-like symptoms
is 2 – 12 weeks. This is called the incubation period.
Early symptoms of the disease include malaise, headache
and fever, progressing to acute pain, restlessness,
depression, and hydrophobia. Finally, the patients may
develop convulsions, muscles paralysis starting at the site of
the bite or scratch, and experiences periods of mania and
lethargy. Eventually, a coma slowly develops. Death occurs
due to respiratory insufficiency 10–14 days after the onset of
symptoms (Awoyomi et al., 2007).
As the virus spreads through the central nervous system,
progressive fatal inflammation of the brain and spinal cord
develops. Two forms of the disease can follow (Takayama
2005):
1. The furious or mad form
2. The dumb or paralytic form.

14. People with furious rabies show uncontrolled behavior,
hyperactivity, hydrophobia, and sometimes aerophobia. After
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a few days, death occurs by cardio-respiratory arrest.
The dumb form is a more advanced stage of the furious type.
People with this form of rabies usually have their muscles
gradually become paralyzed, starting at the site of the bite or
scratch, a coma slowly develops and eventually death
occurs.
Furious rabies symptoms result from changes to the limbic
system, and the dumb form results from changes to
neocortex. Other signs such as excitement, salivation and
increased sexual activity result from the effects on the
autonomic nervous system (Drew 2004).

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6.0 EFFECTS OF RABIES
Rabies disease is known to affect the spinal cord and the
brain. This infection travels to the spinal cord and then to the
brain through the peripheral nerves. Undiagnosed, delayed
or untreated rabies causes acute encephalitis (inflammation
of the brain), damage to the nervous system, muscles
paralysis, and death (Drew 2004).

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7.0 DIAGNOSIS OF RABIES
Rabies can be diagnosed in several ways such as laboratory
test that isolate the virus from the patient’s saliva or throat
or corneal impression, skin biopsies and post-mortem tissue
samples by Fluorescent Antibody Test (FAT) or by the Avidin-
Biotin technique.

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8.0 TREATMENT OF RABIES
Treatment is by means of Intradermal injections of rabies
vaccines, Antiserum and Immunoglobulin which may prevent
the virus from infecting if given within two (2) days. The
required vaccines for the treatment of rabies according to
World Health Organization (WHO) include;
 Human Diploid Cell Vaccine (HDCV): Rabivac™;
 Purified Vero Cell Vaccine (PVRV): Verorab, Imovax,
Rabies vero, TRC Verorab™;
 Purified Chicken Embryo Cell Vaccine (PCECV):
Rabipur™.
The incubation period for rabies enables effective treatment
to be given, but if symptoms appear, they are treated with
sedative drugs and analgesic drugs (Jackson 2008; Suzuki et
al., 2008).

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9.0 PREVENTION AND CONTROL
Preventive and control measures include:
 Immunization of all dogs and cats owned by an
individual or by the community,
 Immunization of persons with proven or probable
exposure to rabies and administer rabies
immunoglobulin in case of severe exposure (WHO
2005),
 Vaccination and elimination of stray dogs should be
enforced.
 Wild animals should not be kept as pets,
 Killing of wildlife around during an epidemic,
 Humans at high risk (e.g. laboratory personnel,
professions at high risk) must receive pre-exposure
immunization,
 People living or travelling to countries where rabies is
endemic should be vaccinated with three doses of
human diploid cell rabies vaccine (Adedeji et al.,
2010),
 Strict quarantine regulations,

19.  Lastly, oral vaccines should be given to wild animals
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through bait. (WHO, 1997)

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10.0 CONCLUSION
Rabies is a neglected disease of the poor and vulnerable
populations whose deaths are rarely reported. It occurs
mainly in rural communities where measure to prevent dog
to human transmission have not been implemented.
Eradication of rabies should be geared towards prevention,
control and treatment. This could be achieved through health
education, improvement of quarantine regulation and human
and animal vaccination. It can be wiped out across the world
if sufficient vaccinations are carried out on domestic dogs. If
prompt medical care is available, rabies is uncommon in
human beings but remains one of the most feared diseases.

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