PRO/AH/EDR> Q fever – South Korea


A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases

Date: Wed 21 Jun 2023 06:13 KST
Source: Yonhap News Agency [in Korean, machine trans., edited]

An analysis came out that Q fever, a zoonotic disease with a high
fatality rate, is likely to become sporadically prevalent in Korea, so
it is necessary to be alert.

Q fever is a disease caused by infection with the bacterium Coxiella
and was designated as a notifiable infectious disease in
Korea in 2006. When infected with Q fever, fever, muscle pain, chills,
and acute hepatitis similar to influenza appear, and about 5% of
infected patients progress to chronic Q fever, which presents as
endocarditis or vascular infection, and active disease management is
important as it has a mortality rate of about 20%, even with
appropriate treatment.

The main source of infection is milk, urine, or calving products of
cows, sheep, and goats infected with Q fever, but infection can also
be mediated through wild animals, pets, birds, and ticks. Humans are
infected through inhalation of germs converted into aerosols (fine
particles), and these aerosols can spread up to 5 to 15 km [3-9 mi] from the source of infection. Although there have been cases of
infection in hospitals after a pregnant woman infected in a foreign
country gave birth, human-to-human transmission is considered
extremely rare.

According to the latest issue of JKMS [Journal of Korean Medical
Science; see citation below] published by the Korean Medical
Association on 21 Jun 2023, as a result of analysis by Professor
Joong-Yeon Huh of the Department of Infectious Diseases at Ajou
University School of Medicine and a joint research team at the
Agriculture, Forestry and Livestock Quarantine Headquarters, around 10
cases domestic Q fever have been reported every year for several years
since the designation as a notifiable infectious disease, but in 2015,
the number of patients began to soar, reaching a peak of 163 cases in

Although the number of reports of Q fever has decreased again since
2020, the research team analyzes that this is likely due to the
COVID-19 pandemic that started in 2020 and changes in diagnostic
criteria, rather than a lowered risk of Q fever.

The research team said, “According to the epidemiological survey of Q
fever in Korea, the average incidence rate was low at 0.07 per 100 000
people per year from 2011 to 2017, but increased rapidly to 0.19 per
100 000 people in 2017″ and South Chungcheong Province showed a much
higher incidence (0.27 cases per 100 000 people per year) than other
regions,” he said.

The epidemiological characteristics of patients with Q fever include
occupational contact with animals or animal products in 24% of
reported cases. Mainly contacted animals were goats (60.0%) and dairy
cows (32.0%).

However, only 18.5% of infected people not related to occupational
exposure had a history of contact with animals. This suggests that it
is difficult to determine the cause of Q fever through epidemiological
studies alone, the research team explained.

The research team cited the case of the Q fever epidemic in the
Netherlands and pointed out that Korea also needs to actively respond.
In the Netherlands, between 2007 and 2010, there were about 4100 cases
of acute or chronic Q fever in the southeast, resulting in 19 deaths.
At the beginning of the outbreak, Q fever spread further as the Dutch
government took passive measures such as voluntary vaccination, and
eventually, the infection ended after killing more than 50 000
pregnant goats and sheep raised on the farm where the infection
occurred. At the time, the economic damage caused by Q fever was
estimated to reach up to 336 million euros (approximately 469.4
billion won).

Considering the size and major types of livestock raised on domestic
farms, the research team believes that the possibility of large-scale
Q fever outbreaks, such as that occurred in the Netherlands where goat
and sheep breeding densities were high, is small but sporadic
small-scale outbreaks centered in densely populated suburbs are likely
to occur.

Furthermore, according to the statistics of the Korea Animal Health
Integrated System, the number of cases of Q fever in domestic animals
continues to increase, from 14 cases in 2015 to 170 cases in 2021.

“Human Q fever is likely an underdiagnosed disease because of its
non-specific symptoms and diagnostic difficulties that require testing
on paired serum samples taken 4-6 weeks apart,” said the research
team. “Considering the potential impact on economic and social losses,
it is necessary to strengthen the epidemiological investigation and
surveillance system in Korea and take preemptive preventive measures
to minimize the risk of Q fever through a comprehensive One Health

[Byline: Kim Gil-wo]

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