Diarrhoea ARI hepatitis hepatitisE
Hepat it is E
Key facts
Hepaiis E is a viral liver disease that can cause mild to severe illness.
It is spread by faecal-oral (or stool to mouth) transmission when a person ingests food
or drink contaminated by an infected person’s stool.
The disease is closely associated with poor sanitaion and a lack of personal hygiene
habits, such as hand-washing.
There are an esimated 14 million symptomaic cases of hepaiis E worldwide; 300 000
deaths and 5200 sillbirths occur annually.
Epidemics can grow rapidly and with high mortality among pregnant women.
There is evidence of foodborne transmission of hepaiis E.
Improved sanitaion is the most effecive way to combat the disease.
There is no commercially available vaccine for this infecion.
Hepaiis E (HEV) was not recognized as a disinct human disease unil 1980. Hepaiis E is caused
by infecion with the hepaiis E virus, a non-enveloped, posiive-sense, single-stranded RNA virus.
Four genotype, 1, 2, 3 and 4 been recognized for HEV. Each HEV genotype appears to have a
specific geographic distribuion. Genotype 1 HEV has been isolated from human cases of epidemic
and sporadic hepaiis E in parts of Asia and Africa, where the disease is highly endemic. Genotype
2 sequences, first reported from an outbreak of hepaiis E in Mexico, have subsequently been
reported from cases in western Africa. Genotype 3 HEV, first idenified in a few rare cases of locallyacquired hepaiis E in the United States has subsequently been reported from human cases in
several industrialized countries in Europe as well as in Asia and Pacific, Genotype 4 HEV has been
found in sporadic cases with acute hepaiis from China, Taiwan, Japan and Vietnam. All genotypes
share at least one major serologically cross-reacive epitope and belong to a single serotype.
Genotype 3 and 4 isolates of HEV appear to be somewhat less pathogenic in humans than those
from genotypes 1 and 2.
Although man is considered the natural host for HEV, anibodies to HEV or closely-related viruses
have been detected in primates and several other animal species.
How is HEV transmitted?
HEV is transmited via the faecal-oral route. Hepaiis E is a waterborne disease, and contaminated
water or food supplies have been implicated in major outbreaks. Consumpion of faecal-contaminated
drinking water has given rise to epidemics, and the ingesion of raw or uncooked shellfish has been
the source of sporadic cases in endemic areas. There is a possibility of zoonoic spread of the virus,
since several non-human primates, pigs, cows, sheep, goats and rodents are suscepible to infecion.
The risk factors for HEV infecion are related poor sanitaion in large areas of the world, and HEV
shedding in feces.
1
Hepat it is E
Person-to-person transmission is uncommon. There is no evidence for sexual transmission or
for transmission by transfusion.
Where is HEV a problem?
The highest rates of infecion occur in regions where low standards of sanitaion promote the
transmission of the virus. Epidemics of hepaiis E have been reported in Central and South-East Asia,
North and West Africa, and in Mexico, especially where faecal contaminaion of drinking water is
common. However, sporadic cases of hepaiis E have also been reported elsewhere and serological
surveys suggest a global distribuion of strains of hepaiis E.
When is a HEV infection life-threatening?
In general, hepaiis E is a self-limiing viral infecion followed by recovery. Prolonged viraemia or
faecal shedding are unusual and chronic infecion does not occur.
Occasionally, a fulminant form of hepaiis develops, with overall paient populaion mortality
rates ranging between 0.5% - 4.0%. Fulminate hepaiis occurs more frequently in pregnancy and
regularly induces a mortality rate of 20% among pregnant women in the third trimester. There is
evidence that acute HEV in persons with chronic HBV or HCV infecions could have severe hepaiis
and liver funcion failure.
The disease
The incubaion period following exposure to HEV ranges from 3 to 8 weeks, with a mean of 40 days.
The period of communicability is unknown. There are no chronic infecions reported.
Hepaiis E virus causes acute sporadic and epidemic viral hepaiis. Symptomaic HEV infecion
is most common in young adults aged 15 – 40 years. Although HEV infecion is frequent in children,
it is mostly asymptomaic or causes a very mild illness without jaundice (anicteric) that goes
undiagnosed.
Typical signs and symptoms of hepaiis include jaundice (yellow discolouraion of the skin and
sclera of the eyes, dark urine and pale stools), anorexia (loss of appeite), an enlarged, tender liver
(hepatomegaly), abdominal pain and tenderness, nausea and vomiing, and fever, although the
disease may range in severity from subclinical to fulminant.
Diagnosis
Since cases of hepaiis E are not clinically disinguishable from other types of acute viral hepaiis,
diagnosis is made by blood tests which detect elevated anibody levels of specific anibodies to
hepaiis E in the body or by reverse transcriptase polymerase chain reacion (RT-PCR). Unfortunately,
such tests are not widely available.
Hepaiis E should be suspected in outbreaks of waterborne hepaiis occurring in developing
countries, especially if the disease is more severe in pregnant women, or if hepaiis A has been
excluded. If laboratory tests are not available, epidemiologic evidence can help in establishing a
diagnosis.
2
Surveillance and control procedures should include
provision of safe drinking water and proper disposal of sanitary waste;
monitoring of disease incidence;
determination of source of infection and mode of transmission by epidemiologic
invesigaion;
detecion of outbreaks;
spread containment.
Hepat it is E
Surveillance and control
Vaccines
At present, no commercially available vaccine exists for the prevenion of hepaiis E. However,
several studies for the development of an effecive vaccine against hepaiis E are in progress.
Prevention
As almost all HEV infecions are spread by the faecal-oral route, good personal hygiene, high quality
standards for public water supplies and proper disposal of sanitary waste have resulted in a low
prevalence of HEV infecions in many well developed socieies.
For travelers to highly endemic areas, the usual elementary food hygiene precauions are
recommended. These include avoiding drinking water and/or ice of unknown purity and eaing
uncooked shellfish, uncooked fruits or vegetables that are not peeled or prepared by the traveler.
Treatment
Hepaiis E is a viral disease, and as such, anibioics are of no value in the treatment of the infecion.
There is no hyper immune E globulin available for pre- or post-exposure prophylaxis. HEV infecions
are usually self-limited, and hospitalizaion is generally not required. No available therapy is capable
of altering the course of acute infecion.
As no specific therapy is capable of altering the course of acute hepaiis E infecion, prevenion
is the most effecive approach against the disease. Hospitalizaion is required for fulminant hepaiis
and should be considered for infected pregnant women.
Guidelines for epidemic measures
Determinaion of the mode of transmission.
Idenificaion of the populaion exposed to increased risk of infecion.
Eliminaion of a common source of infecion.
Improvement of sanitary and hygienic pracices to eliminate faecal contaminaion of food and
water.
3
Key facts
Hepaiis E is a viral liver disease that can cause mild to severe illness.
It is spread by faecal-oral (or stool to mouth) transmission when a person ingests food
or drink contaminated by an infected person’s stool.
The disease is closely associated with poor sanitaion and a lack of personal hygiene
habits, such as hand-washing.
There are an esimated 14 million symptomaic cases of hepaiis E worldwide; 300 000
deaths and 5200 sillbirths occur annually.
Epidemics can grow rapidly and with high mortality among pregnant women.
There is evidence of foodborne transmission of hepaiis E.
Improved sanitaion is the most effecive way to combat the disease.
There is no commercially available vaccine for this infecion.
Hepaiis E (HEV) was not recognized as a disinct human disease unil 1980. Hepaiis E is caused
by infecion with the hepaiis E virus, a non-enveloped, posiive-sense, single-stranded RNA virus.
Four genotype, 1, 2, 3 and 4 been recognized for HEV. Each HEV genotype appears to have a
specific geographic distribuion. Genotype 1 HEV has been isolated from human cases of epidemic
and sporadic hepaiis E in parts of Asia and Africa, where the disease is highly endemic. Genotype
2 sequences, first reported from an outbreak of hepaiis E in Mexico, have subsequently been
reported from cases in western Africa. Genotype 3 HEV, first idenified in a few rare cases of locallyacquired hepaiis E in the United States has subsequently been reported from human cases in
several industrialized countries in Europe as well as in Asia and Pacific, Genotype 4 HEV has been
found in sporadic cases with acute hepaiis from China, Taiwan, Japan and Vietnam. All genotypes
share at least one major serologically cross-reacive epitope and belong to a single serotype.
Genotype 3 and 4 isolates of HEV appear to be somewhat less pathogenic in humans than those
from genotypes 1 and 2.
Although man is considered the natural host for HEV, anibodies to HEV or closely-related viruses
have been detected in primates and several other animal species.
How is HEV transmitted?
HEV is transmited via the faecal-oral route. Hepaiis E is a waterborne disease, and contaminated
water or food supplies have been implicated in major outbreaks. Consumpion of faecal-contaminated
drinking water has given rise to epidemics, and the ingesion of raw or uncooked shellfish has been
the source of sporadic cases in endemic areas. There is a possibility of zoonoic spread of the virus,
since several non-human primates, pigs, cows, sheep, goats and rodents are suscepible to infecion.
The risk factors for HEV infecion are related poor sanitaion in large areas of the world, and HEV
shedding in feces.
1
Hepat it is E
Person-to-person transmission is uncommon. There is no evidence for sexual transmission or
for transmission by transfusion.
Where is HEV a problem?
The highest rates of infecion occur in regions where low standards of sanitaion promote the
transmission of the virus. Epidemics of hepaiis E have been reported in Central and South-East Asia,
North and West Africa, and in Mexico, especially where faecal contaminaion of drinking water is
common. However, sporadic cases of hepaiis E have also been reported elsewhere and serological
surveys suggest a global distribuion of strains of hepaiis E.
When is a HEV infection life-threatening?
In general, hepaiis E is a self-limiing viral infecion followed by recovery. Prolonged viraemia or
faecal shedding are unusual and chronic infecion does not occur.
Occasionally, a fulminant form of hepaiis develops, with overall paient populaion mortality
rates ranging between 0.5% - 4.0%. Fulminate hepaiis occurs more frequently in pregnancy and
regularly induces a mortality rate of 20% among pregnant women in the third trimester. There is
evidence that acute HEV in persons with chronic HBV or HCV infecions could have severe hepaiis
and liver funcion failure.
The disease
The incubaion period following exposure to HEV ranges from 3 to 8 weeks, with a mean of 40 days.
The period of communicability is unknown. There are no chronic infecions reported.
Hepaiis E virus causes acute sporadic and epidemic viral hepaiis. Symptomaic HEV infecion
is most common in young adults aged 15 – 40 years. Although HEV infecion is frequent in children,
it is mostly asymptomaic or causes a very mild illness without jaundice (anicteric) that goes
undiagnosed.
Typical signs and symptoms of hepaiis include jaundice (yellow discolouraion of the skin and
sclera of the eyes, dark urine and pale stools), anorexia (loss of appeite), an enlarged, tender liver
(hepatomegaly), abdominal pain and tenderness, nausea and vomiing, and fever, although the
disease may range in severity from subclinical to fulminant.
Diagnosis
Since cases of hepaiis E are not clinically disinguishable from other types of acute viral hepaiis,
diagnosis is made by blood tests which detect elevated anibody levels of specific anibodies to
hepaiis E in the body or by reverse transcriptase polymerase chain reacion (RT-PCR). Unfortunately,
such tests are not widely available.
Hepaiis E should be suspected in outbreaks of waterborne hepaiis occurring in developing
countries, especially if the disease is more severe in pregnant women, or if hepaiis A has been
excluded. If laboratory tests are not available, epidemiologic evidence can help in establishing a
diagnosis.
2
Surveillance and control procedures should include
provision of safe drinking water and proper disposal of sanitary waste;
monitoring of disease incidence;
determination of source of infection and mode of transmission by epidemiologic
invesigaion;
detecion of outbreaks;
spread containment.
Hepat it is E
Surveillance and control
Vaccines
At present, no commercially available vaccine exists for the prevenion of hepaiis E. However,
several studies for the development of an effecive vaccine against hepaiis E are in progress.
Prevention
As almost all HEV infecions are spread by the faecal-oral route, good personal hygiene, high quality
standards for public water supplies and proper disposal of sanitary waste have resulted in a low
prevalence of HEV infecions in many well developed socieies.
For travelers to highly endemic areas, the usual elementary food hygiene precauions are
recommended. These include avoiding drinking water and/or ice of unknown purity and eaing
uncooked shellfish, uncooked fruits or vegetables that are not peeled or prepared by the traveler.
Treatment
Hepaiis E is a viral disease, and as such, anibioics are of no value in the treatment of the infecion.
There is no hyper immune E globulin available for pre- or post-exposure prophylaxis. HEV infecions
are usually self-limited, and hospitalizaion is generally not required. No available therapy is capable
of altering the course of acute infecion.
As no specific therapy is capable of altering the course of acute hepaiis E infecion, prevenion
is the most effecive approach against the disease. Hospitalizaion is required for fulminant hepaiis
and should be considered for infected pregnant women.
Guidelines for epidemic measures
Determinaion of the mode of transmission.
Idenificaion of the populaion exposed to increased risk of infecion.
Eliminaion of a common source of infecion.
Improvement of sanitary and hygienic pracices to eliminate faecal contaminaion of food and
water.
3