summary rabies

7/29/2019 summary rabies

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CHAPTER 1

INTRODUCTION

1.1 Background

Travel medicine is one branch of medicine dealing with prevention and management

of health problem of international travelers. Globalization makes people can easily

travel form one part of the world to another faster and rapidly, thereby it facilitates the

spread of disease, increases the number of travelers who will be exposed to a different

health environment.

Infectious disease accounts for about 2,8 4% of total deaths during or from travel.

Rabies is one of the infectious diseases with highest fatality rate of all known human

viral pathogens. Almost all of rabies victims reside in Asia and Africa especially in

rural areas primarily due to stray dogs.There is no specific treatment of rabies once

clinical signs have developed, and death is an almost universal outcome. Therefore

pre-travel preventive and promotive measures are absolute musts for travelers who

travel to rabies endemic areas.

1.2 Problem Identification

This Report discusses about the risk of exposure to rabies among foreign travelers

specifically speaking in rabies endemic areas, rabies prevention strategies including

the pre-exposure and post-exposure prophylaxis and the advances in diagnostic testing

to diagnose rabies.

1.3 Aims and Benefit

This report is expected to expand the knowledge about rabies prevention and

promotive measures for medical personnel to be able to give pre-travel advice to

travelers going to rabies endemic areas and for the travelers themselves to be aware to

the risk of rabies while travelling to rabies endemic area.


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CHAPTER 2

LITERATURE REVIEW

2.1Journal 1 Summary

Title : Rabies Exposure Risk among Foreign Backpackers in Southeast Asia

Summary :

Rabies remains a problem in most countries of Southeast Asia, where stray dogs and

cats are common. Local people and travelers in this area are inevitably at risk of

exposure to the rabies virus. Pre-exposure prophylaxis is an excellent preventive

measure against rabies but in other hand the cost-benefit relationship of pre-exposure

vaccination is still debatable.

Data were collected from 870 foreign backpackers using questionnaire. The

questionnaire was comprised four parts that was general information about the

travelers, rabies pre-exposure preparations, knowledge about rabies, and the details of

any animal exposure.

Although 80.7% had sought travel health information before travel, only 55.6% had

received information about rabies.70.9% had not been vaccinated for rabies at all and

among those 61,8% cited the cost of the vaccine; 11,8% did not of or were unaware of

the risk of rabies and 9,3% thought that unnecessary. 95,7% backpackers knew that

they could get rabies if bitten by infected animals but only 59% of them who knew

that being licked on an open wound could also transmit rabies virus. 98% knew that

dogs could carry rabies virus, but only about half of them aware that other mammals

could also carry the virus. Moreover 40% thought the bite of healthy-looking dog

posed no risk of rabies.

On an average stay of a month, 3.6% had been licked, whereas 6 of 870 backpackers

(0.69%) had been bitten. 54% of exposures took place within the first 10 days after

arrival in Southeast Asia. The animals most commonly encountered were dogs,

followed by cats and monkeys. Among those who were bitten, only 67% sought

medical care, and only 50% received post-exposure treatment.


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Conclusion :

Only 55.6% of the travelers had received information about rabies, 70.9% had not

been vaccinated for rabies at all, 59% of them who knew that rabies could be

transmitted aside from via bite, half of travelers didnt know mammals beside dogs

can carry the virus and 40% thought a healthy looking dog poses no risk of rabies. It

is clear that travelers are at risk of rabies exposure and the disease is virtually fatal

once symptoms develop. Therefore, many international guidelines recommend pre-

exposure rabies vaccination for travelers in rabies-endemic areas. Health education is

also important to prevent misconceptions, misunderstandings and lack of awareness.

The combination of these two is a good strategy to prevent rabies in travelers since

standard post-exposure treatment might be not available especially in rural areas.



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Title : Rabies Prevention in Traveler

Summary :

Rabies is an acute, almost invariably fatal, progressive encephalomyelitis caused byneurotropic lyssaviruses of the Rhabdoviridae family. Rabies virus present in the

saliva of an infected animal. It most commonly transmitted via animal bite and rarely

via scratches to skin, licks to open wounds or mucous membranes. The virus travels to

the brain along the nerve. The density of nerve endings in the bitten area, the

proximity of the bite site to the central nervous system (CNS), and the severity of the

bite, determines how quickly the virus cause rabies encephalitis. The incubation

period can range from 112 weeks to several years. Prodromal symptoms are

nonspecific only showing common mild symptom. Most commonly the disease will

progress to furious encephalitic rabies with symptoms such as aerophobia,

hydrophobia and hyper salivation.

Rabies viruses are present in most parts of the world, although it is mainly a problem

in developing countries. Over 50.000 people die of rabies each year and 95% victims

resides in Asia and Africa. 80% of the cases occur in rural areas. Countries at greatest

risk are India, Nepal, Sri Lanka, El Salvador, Guatemala, Peru, Colombia, Ecuador

and some Shouth-East Asia Nations. As for in Indonesia Rabies has been reported in

Bali, Islands of Flores, Sulawesi, Sumatra, Ambon and Kalimantan.

High level of contact to animal and extensive outdoor exposure can increase risk to be

exposed to rabies virus. All travelers should avoid approaching stray animals, stay

aware to avoid surprising stray dogs or bats and avoid carrying or eating food in

presence of monkeys.

People at high risk and long term travelers to rabies endemic or isolated areas should

be offered with pre-exposure vaccination. There are several kinds of vaccines exist

such as HDCV, PCECV, PVRV, RVA and Lyssavac. The vaccines must be given via

the deltoid region in adults and via the anterolateral aspect of the thigh in children

under 12 months. Individual with anaphylactic sensitivity to eggs or egg proteins

should be given HDCV instead of PCECV. More than 200 cases of successful

maternal vaccination during pregnancy without adverse fetal outcomes have been

reported.


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Post-Exposure Prophylaxis (PEP) is needed to prevent clinical rabies after exposure

has occurred. It includes thorough wound cleansing and disinfection, passive

immunization by installation of rabies neutralizing antibodies into the wound and

stimulation of an active immune response with rabies vaccine. Recommended PEPdepends on the category of risk of

All wounds must be thoroughly cleaned with copious soap or detergent and water,

followed by poviodone iodine. Suturing only should be delayed, and if is unavoidable,

the wound should be infiltrated with rabies immune globulin (RIG) then suturing can

be performed after at least several hours later.

All category III and category II should receive RIG. Due to global shortage of HRIG

unlike most of developed country, many developing countries use ERIG instead. This

is preferable to not administering RIG at all, and the incidence of adverse reactions,

mainly serum sickness (which commonly occurs a week later), is low (0.86.0%). A

recent study suggests that the mandatory skin test recommended before ERIG

administration does not necessarily predict serum sickness. Post-exposure prophylaxis

may be ceased if the animal is definitely found to be negative for rabies after testing

in a reputable laboratory, or if the animal has remained well after 10 days.

Conclusion :

All travelers require education regarding rabies prevention if travelling to a rabies

endemic area. Those at high risk of exposure should be offered pre-exposure

vaccination. Modern cell culture vaccines are well tolerated, although cost and time

taken to complete the course can be of concern to travelers. Post-exposure prophylaxis

should always be commenced where indicated, as no contraindications exist.


Title : Advances in Diagnosis of Rabies


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Summary :

Rabies virus is a neurotropic virus of the genus Lyssavirus of the family

Rhabdoviridae and transmissible to human by inoculation or inhalation of infectious

virus. There are seven distinct genetic lineages can be distinguished within the genus

Lyssavirus classical rabies virus itself (RABV genotype 1, serotype 1), Lagos batvirus (LBV, genotype 2, serotype 2), Mokola virus (MOKV, genotype 3, serotype 3),

and Duvenhage virus (DUUV, genotype 4, serotype 4). The European bat lyssaviruses

(EBLV) subdivided into two biotypes (EBLV1, genotype 5 and EBLV2, genotype 6)

and the Australian bat lyssavirus (ABLV, genotype 7).

Conserved antigenic sites on the nucleocapsid proteins permit recognition of all

lyssaviruses with modern commercial preparations of anti-rabies antibody conjugates

used for diagnostic tests on brain tissue. Humans working with suspect material must

be vaccinated against lyssaviruses or other pathogens that may be present in

diagnostic samples. As no clinical sign or gross post-mortem lesion can be considered

pathognomonic in domestic or wild animals, the diagnosis of rabies has to rely on

laboratory testing. Serological evidence of infection is rarely useful because of late

seroconversion and the high mortality rate of host species, although such data may be

used in some epidemiological surveys.

The only way to perform a reliable diagnosis of rabies is to identify the virus or some

of its specific components using laboratory tests. Several laboratory techniques may

be used; the methods vary in their efficiency, specificity and reliability. They are

preferable conducted in CNS tissue and the virus is particularly abundant in the

thalamus, pons and medulla. Removing the entire organ is necessary to collect and

test the brain tissues needed, but under some circumstances a simplified method ofsampling through the occipital foramen, or through the orbital cavity can be used.

During the shipment of suspect material for diagnosis no risk of human contamination

should arise.When it is not possible to send refrigerated samples, other preservationtechniques may be used.The choice of the preservative is closely linked to the tests to

be used for diagnosis.

The most widely used test for rabies diagnosis is the fluorescent antibody test (FAT).

The sensitivity of the FAT depends on the degree of autolysis and how


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comprehensively the brain is sampled, on the type of lyssavirus and on the proficiency

of the diagnostic staff.

The antibody may be conjugated to an enzyme such as peroxidase instead of

fluorescein isothiocyanate (FITC). This conjugate may be used for direct diagnosis

with the same sensitivity as FAT, but attention should be paid to the risk of

nonspecific false-positive results. This risk is considerably reduced by the thorough

training of the technicians. It must also be emphasised that this technique needs one

incubation step more than the FAT.

In case that FAT gives an uncertain result or when the FAT is negative in the case of

known human exposure, detection of the replication of rabies virus must be done.

There are some tests to detect the infectivity of a tissue suspension in cell cultures or

in laboratory animals, such as:

Mouse inoculation test: Five-to-ten mice, 3-4 weeks old (12-14 g), or a litter of 2-

day-old newborn mice, are inoculated intracerebrally. The young adult mice are

observed daily for 28 days, and every dead mouse is examined for rabies using the

FAT

Cell culture test: Neuroblastoma cell lines, e.g. CCL-131 in the American Type

Culture Collection are used for routine diagnosis of rabies. The cells are grown in

Dulbeccos modified Eagles medium (DMEM) with 5% fetal calf serum (FCS),

incubated at 36C with 5% CO2. Its sensitivity has been compared with that of baby

hamster kidney (BHK-21) cells. Presence of rabies virus in the cells is revealed by the

FAT. The result of the test is obtained after at least 18 hour.

Serological tests are rarely used in epidemiological surveys, due to late

seroconversion and the low percentage of animals surviving the disease and therefore

having post-infection antibodies. There are some types of serological test, such as:

a. fluorescent antibody virus neutralisation test

The principle of the fluorescent antibody virus neutralisation (FAVN) test is the

neutralisation in vitro of a constant amount of rabies virus (challenge virus

standard [CVS] strain adapted to cell culture) before inoculating cells susceptible

to rabies virus


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b. The rapid fluorescent focus inhibition test (RFFIT)

A serological test based on the ability of neutralising antibodies to inhibit the

growth, in cell culture, of challenge virus.

c. Virus neutralisation in mice (no longer recommended)

d. Enzyme-linked immunosorbent assay (ELISA)

Commercial kits are available for indirect ELISA that allow a qualitative

detection of rabies antibodies in individual dog and cat serum samples following

vaccination. ELISA methods are useful for monitoring of vaccination campaigns

in wildlife populations

For follow-up investigations in oral vaccination campaigns, virus neutralisation (VN)

tests in cell culture are preferred. However, if poor quality sera are submitted, the VN

tests in cell culture are sensitive to cytotoxicity, which could lead to false-positive

results. For such samples, the use of an indirect ELISA with rabies glycoprotein-

coated plates has been shown to be as sensitive and specific as the VN test on cells.

Conclusion :

There are seven distinct genetic lineages in the genus of Lyssavirus which only the

RABV is the classical rabies virus while the others are all known as rabies-related

viruses. The only way to perform reliable diagnosis is from laboratory testing.

Laboratory techniques are preferably conducted on CNS tissue. The agent

identification is preferably done using the FAT because it provides a reliable

diagnosis in 98-100% of cases for all genotypes if a potent conjugate is used. There

are several types of serological tests such as FAVN, RFFIT, VN and ELISA.

CHAPTER 3

CONCLUSION

3.1 Conclusion


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All travelers travelling from developed country to developing country especially those

who travel off the usual tourist routes are more likely at higher risk of exposure to

rabies. Moreover the travelers preparations and knowledge regarding rabies are

usually low. This may lead to misconception and misunderstanding and increase therisk to rabies exposure. Therefore travelers are advised to see physician before going

to rabies endemic area especially to rural area. Although the cost might become a

concern for travelers, a complete course of pre-exposure vaccination, three shots, is

highly recommended. Post-exposure prophylaxis should always be commenced where

indicated. Laboratory testing is the only way to perform reliable diagnosis of rabies

conducted in CNS tissues. The most widely used diagnostic test for rabies is FAT.

The FAT can provides a reliable diagnosis in 98-100% of cases for all genotypes if a

potent conjugate is used.

summary rabies

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