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Transmission of Hepatitis E Virus in Developing Countries

View Article: PubMed Central - PubMed

ABSTRACT

Hepatitis E virus (HEV), an RNA virus of the Hepeviridae family, has marked heterogeneity. While all five HEV genotypes can cause human infections, genotypes HEV-1 and -2 infect humans alone, genotypes HEV-3 and -4 primarily infect pigs, boars and deer, and genotype HEV-7 primarily infects dromedaries. The global distribution of HEV has distinct epidemiological patterns based on ecology and socioeconomic factors. In resource-poor countries, disease presents as large-scale waterborne epidemics, and few epidemics have spread through person-to-person contact; however, endemic diseases within these countries can potentially spread through person-to-person contact or fecally contaminated water and foods. Vertical transmission of HEV from infected mother to fetus causes high fetal and perinatal mortality. Other means of transmission, such as zoonotic transmission, can fluctuate depending upon the region and strain of the virus. For instance, zoonotic transmission can sometimes play an insignificant role in human infections, such as in India, where human and pig HEV infections are unrelated. However, recently China and Southeast Asia have experienced a zoonotic spread of HEV-4 from pigs to humans and this has become the dominant mode of transmission of hepatitis E in eastern China. Zoonotic HEV infections in humans occur by eating undercooked pig flesh, raw liver, and sausages; through vocational contact; or via pig slurry, which leads to environmental contamination of agricultural products and seafood. Lastly, blood transfusion-associated HEV infections occur in many countries and screening of donors for HEV RNA is currently under serious consideration. To summarize, HEV genotypes 1 and 2 cause epidemic and endemic diseases in resource poor countries, primarily spreading through contaminated drinking water. HEV genotypes 3 and 4 on the other hand, cause autochthonous infections in developed, and many developing countries, by means of a unique zoonotic food-borne transmission.

No MeSH data available.


Epidemic region: Kashmir, 1978. Drinking water is collected from a canal in which public latrine sewage flows, garbage of the whole locality is dumped, utensils and linen are washed, children swim, and locals buy fish (Adapted from Khuroo, et al. [4]).
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viruses-08-00253-f003: Epidemic region: Kashmir, 1978. Drinking water is collected from a canal in which public latrine sewage flows, garbage of the whole locality is dumped, utensils and linen are washed, children swim, and locals buy fish (Adapted from Khuroo, et al. [4]).

Mentions: The mechanism of water contamination differs from one region to another; however, it typically follows a uniform pattern in repeated outbreaks within the same region, which is vital to understand, in order for public health officials to control any current and future epidemics [3]. Several different types of environmental settings have documented water contamination (Figure 2). Epidemics can result from contamination of river water used for drinking, washing, bathing, and sewage disposal (Figure 3) [4,39,64]. Outbreaks in such settings usually occur during winter months when the water level falls, thereby increasing the level of water contamination due to an increase in contaminant concentration [3]. Groundwater, crops, and waterways can all become contaminated. Open defecation in backyards and open fields can be another source of fecal contamination of groundwater, crops, and waterways [65]. In India for example, open defecation is rampant and over 300 million people use this practice for sanitary disposal, leading to widespread contamination of open drinking water sources, such as rivers, streams, and unprotected wells with raw sewage [2].


Transmission of Hepatitis E Virus in Developing Countries
Epidemic region: Kashmir, 1978. Drinking water is collected from a canal in which public latrine sewage flows, garbage of the whole locality is dumped, utensils and linen are washed, children swim, and locals buy fish (Adapted from Khuroo, et al. [4]).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5035967&req=5

viruses-08-00253-f003: Epidemic region: Kashmir, 1978. Drinking water is collected from a canal in which public latrine sewage flows, garbage of the whole locality is dumped, utensils and linen are washed, children swim, and locals buy fish (Adapted from Khuroo, et al. [4]).
Mentions: The mechanism of water contamination differs from one region to another; however, it typically follows a uniform pattern in repeated outbreaks within the same region, which is vital to understand, in order for public health officials to control any current and future epidemics [3]. Several different types of environmental settings have documented water contamination (Figure 2). Epidemics can result from contamination of river water used for drinking, washing, bathing, and sewage disposal (Figure 3) [4,39,64]. Outbreaks in such settings usually occur during winter months when the water level falls, thereby increasing the level of water contamination due to an increase in contaminant concentration [3]. Groundwater, crops, and waterways can all become contaminated. Open defecation in backyards and open fields can be another source of fecal contamination of groundwater, crops, and waterways [65]. In India for example, open defecation is rampant and over 300 million people use this practice for sanitary disposal, leading to widespread contamination of open drinking water sources, such as rivers, streams, and unprotected wells with raw sewage [2].

View Article: PubMed Central - PubMed

ABSTRACT

Hepatitis E virus (HEV), an RNA virus of the Hepeviridae family, has marked heterogeneity. While all five HEV genotypes can cause human infections, genotypes HEV-1 and -2 infect humans alone, genotypes HEV-3 and -4 primarily infect pigs, boars and deer, and genotype HEV-7 primarily infects dromedaries. The global distribution of HEV has distinct epidemiological patterns based on ecology and socioeconomic factors. In resource-poor countries, disease presents as large-scale waterborne epidemics, and few epidemics have spread through person-to-person contact; however, endemic diseases within these countries can potentially spread through person-to-person contact or fecally contaminated water and foods. Vertical transmission of HEV from infected mother to fetus causes high fetal and perinatal mortality. Other means of transmission, such as zoonotic transmission, can fluctuate depending upon the region and strain of the virus. For instance, zoonotic transmission can sometimes play an insignificant role in human infections, such as in India, where human and pig HEV infections are unrelated. However, recently China and Southeast Asia have experienced a zoonotic spread of HEV-4 from pigs to humans and this has become the dominant mode of transmission of hepatitis E in eastern China. Zoonotic HEV infections in humans occur by eating undercooked pig flesh, raw liver, and sausages; through vocational contact; or via pig slurry, which leads to environmental contamination of agricultural products and seafood. Lastly, blood transfusion-associated HEV infections occur in many countries and screening of donors for HEV RNA is currently under serious consideration. To summarize, HEV genotypes 1 and 2 cause epidemic and endemic diseases in resource poor countries, primarily spreading through contaminated drinking water. HEV genotypes 3 and 4 on the other hand, cause autochthonous infections in developed, and many developing countries, by means of a unique zoonotic food-borne transmission.

No MeSH data available.