Friday, August 09, 2019

Hong Kong Reports Another Human Infection With Rat Hepatitis E



Less than a year ago Hong Kong University reported the first identified human infection with a rat Hepatitis E virus (see ECDC CDTR Notice) in an elderly immunosuppressed individual who had recently received a liver transplant.

The announcement from HKU reads, in part:
HKU discovers that rat hepatitis E virus can cause hepatitis in humans

28 Sep 2018

Rat hepatitis E virus (rat HEV) was first discovered in 2010 and circulates in house rats (Rattus rattus) and sewer rats (Rattus norvegicus). It is very distantly related to human hepatitis E virus variants. Human infection by rat HEV has never been documented previously.
A study led by Professor Yuen Kwok-Yung, Henry Fok Professor in Infectious Diseases, Chair Professor of Infectious Diseases, and Dr Siddharth Sridhar, Clinical Assistant Professor at the Department of Microbiology of Li Ka Shing Faculty of Medicine, The University of Hong Kong (HKU) has discovered for the first time that rat HEV can infect humans. 

Since then, we've seen about a half dozen cases identified in Hong Kong (see June's Hong Kong Reports 6th Human Infection With Rat Hepatitis E Virus), along with a single case reported in Canada detected in a person with recent travel history to Africa (see Rat hepatitis E may be ‘under-recognized’ cause of hepatitis infection).
It remains unknown just how widespread transmission really is.
While apparently still pretty rare, today Hong Kong's CHP announced the discovery of another human infection.

 The Centre for Health Protection (CHP) of the Department of Health is today (August 9) investigating a case of human infection of rat Hepatitis E virus (HEV) and urged members of the public to be vigilant against hepatitis E infection and to strictly observe good personal, food and environmental hygiene.
The case involves a 43-year-old man with underlying illnesses, who had presented with liver function derangement since May this year. He has been in a stable condition all along and no hospitalisation is required. His blood sample tested positive for rat HEV upon laboratory testing.
The CHP's epidemiological investigations revealed that the patient resided in Kwai Tsing district. He could neither recall having direct contact with rodents or their excreta, nor had noticed rodents in his residence. He had travelled to Shenzhen during the incubation period.
"Based on the available epidemiological information, the source and the route of infection could not be determined. The CHP's investigation is ongoing," a spokesman for the CHP said.
"The CHP has already informed the Pest Control Advisory Section of the Food and Environmental Hygiene Department about the case to carry out rodent control measures and a survey as appropriate," the spokesman added.
The exact mode of transmission of rat HEV to humans is unknown at the moment. Possible routes of transmission include ingestion of food or water contaminated by rodents or their excreta, exposure to environments or objects contaminated by rodents or their excreta and direct contact with rodents or their excreta. The usual HEV causing human infection is transmitted mainly through the faecal-oral route.
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Hong Kong has a notorious`rat problem', and following May's announcement of 3 additional Rat Hepatitis E cases, HK's Food and Health Bureau announced a massive cleanup campaign. 

Yesterday they announced an extension of this eradication campaign until at least November:
The interdepartmental Pest Control Steering Committee met this afternoon (August 8) to review the anti-rodent work carried out by various government departments since the territory-wide cleaning operation commenced on May 20. 

The Committee decided to extend the operation for three months to mid-November to continuously carry out anti-rodent work, in particular, works such as repaving back alleys, installation of rodent-proofing structures in public rental housing (PRH) estates and intensive anti-rodent work in public markets, which require a longer time to complete.

     Various departments briefed the meeting on the progress of territory-wide cleaning work in all 18 districts. They include:

* The Food and Environmental Hygiene Department (FEHD) has collected 5 215 dead rodents, caught 3 906 live rodents as well as filled 2 144 rat holes in the first two months of the territory-wide cleaning operation.

* The Highways Department will complete the repair works of 99 back alleys with damaged road surfaces or surface channels by this month. The department is now planning to partially repave 27 back alleys with relatively serious environmental hygiene problems. The works are expected to be completed within this year.

* The Housing Authority (HA) has already examined the operation of rodent-proofing structures installed in more than 180 PRH estates and found some of the existing structures required maintenance or reinforcement. The relevant works will be commenced progressively and additional structures will be installed in PRH estates when necessary. The works will be tentatively completed by the third quarter of this year.

* The FEHD has carried out a three-month intensive anti-rodent operation in three public markets, namely Lai Wan Market, Ap Lei Chau Market and Kam Tin Market since mid-July. Speedy refuse removal and cleaning of all drainages in the markets have been carried out every night after the stalls are closed to eliminate food sources for rodents. Traps have been extensively placed to strengthen rodent disinfestation.

* The FEHD has organised eight seminars on rodent prevention and control to outsourced cleaning service contractors of departments and property management companies in July.
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Hong Kong is one of the most densely populated cities in the world, with 7.4 million people crammed into 427 square miles (1,110 square kilometers).  While that works out to just over 6,600 people per sq. km., the population is far from evenly dispersed. 
In 2014, Hong Kong's government estimated that Kwun Tong, with 57,250 persons per sq. km., was the most densely populated district in the territory.
Add in its close proximity to, and continual traffic from, Mainland China and Hong Kong becomes an important region for epidemiological surveillance.
It was the first place where H5N1 was identified in the mid-1990s, and it became the nexus of the SARS epidemic in 2003 (see SARS And Remembrance).
While rat hepatitis E doesn't appear to pose much in the way of epidemic potential, we actually know very little about disease's prevalence and epidemiology.  Hong Kong, due to its high population density, and its well-regarded Centre for Health Protection, is in a unique position to provide some answers.