6.3.7. Other diseases of zoonotic and environmental origin
This is a very heterogeneous group of diseases that fall
into two broad categories:
present in Europe (tularaemia, puumala virus infection, borreliosis, tick-borne
encephalitis, Q fever, leptospirosis, anthrax, rabies, and West Nile virus
infection). Some of these diseases have the potential to be used as a
bioterrorism threat (anthrax and tularemia). At present, these diseases have a
low number of cases, are often geographically confined, and have to be seen in
relation to certain animal reservoirs. Surveillance has not been established
for all of them in all countries. For each of these diseases there is a need to
develop tailored monitoring, establish surveillance of outbreaks, monitor risk
factors and standardise laboratory methods.
imported into Europe (malaria, viral haemorrhagic fevers (VHF), and plague).
For these diseases it is important to have sufficient laboratory capacity for
rapid diagnoses in travellers returning from endemic countries.
The most important of the above diseases are tularaemia,
puumala virus infections, borreliosis and tick-borne encephalitis (TBE). Of
these, only tularaemia is under EU surveillance. This is a disease mainly seen
in the North and in sparsely populated areas of central Europe. It appears in
outbreaks at intervals of several years, and any actual trend is difficult to
describe. Puumala virus infection (nephropathia epidemica) could be classified
as VHF, but is seldom reported as such in the EU.
A number of exotic diseases, such as VHF, malaria and
plague should be reported to the EU network, but these cases are almost all
imported. The main reason for surveillance of malaria is not to discover any
transmission in the EU, but rather to ensure that recommendations for
prophylaxis remain valid. Few of these diseases actually pose any major public
health threat to EU citizens. Some of these diseases are prone to outbreaks,
which always attract a great deal of media attention. It is important to follow
their epidemiology in order to give adequate information to the EU public.
Environmental, ecological and climate changes contribute
to the emergence, maintenance and transmission of vector-borne and other
infectious diseases, some of them imported from regions where they are endemic.
The effect of global warming on Europe in the years ahead
could increase this danger.
This is a wide range of diseases with different modes of
transmission and with varying relevance to European public health. More
systematic surveillance data are needed in order to allow for a more
coordinated approach in terms of prevention and control. Imported cases through
travel need to be monitored, in particular where there is the potential for
autochthonous transmission (malaria, chikungunya, yellow
fever, etc.), high infectivity (most VHF), etc. Considering the type
of diseases and their possible impact, we need to be able to ensure rapid
diagnoses for each of them, as well as for unknown pathogens.
present in Europe
Tularaemia is a zoonosis, caused by the bacteria Francisella tularensis. Natural reservoirs
include wild rabbits, hares and muskrats, as well as some domestic animals.
Human infection occurs through a variety of mechanisms such as 1) bites from
infected ticks; 2) direct contact or ingestion of water, food, or soil
contaminated by rodents; 3) handling animal tissues or fluids or undercooked
infected meat; and 4) inhalation of infective aerosols. Human-to-human
transmission has not been documented. A vaccine is available to protect
laboratory personnel routinely working with the bacterium. The pathogen has
been considered as an agent with the potential for intentional release.
In the last 10 years the reported number of cases in the
EU has been very variable, but the overall trend appears to be stable. Finland
and Sweden were the countries reporting the most cases over the last 10 years
and trends for both countries appear to be increasing, although more in Sweden.
In 2005, 508 cases were reported by 21 countries. Sweden (2.73 per
100 000), followed by Hungary (0.86 per 100 000) reported the highest
Puumala haemorrhagic fever with renal syndrome
Puumala haemorrhagic fever with renal syndrome, also
called ‘nephropathia epidemica’, is caused by the puumala virus, and occurs
mainly in Northern Europe and Russia. Transmission to humans occurs through the
inhalation of the virus in aerosols contaminated with the excreta of infected
rodents. Up to 80% of infections may be asymptomatic. Clinical illness results
in haemorrhagic fever with renal syndrome, with a death rate of less than 0.5%.
This disease is the most common haemorrhagic fever in Europe. In the past 10
years, there has been an increase of cases every third year. The year 2005 saw
one of these peaks, with more than 2 500 cases reported by Finland and 330
from Sweden. Higher than usual incidences were also noticed in France, Germany,
Belgium, Austria, and Luxembourg.
Q fever is a zoonosis caused by Coxiella burnetii, characterised by an
acute febrile illness. The natural reservoirs are sheep, cattle, goats, cats,
dogs, birds and some wild animals. Humans are usually infected by direct
inhalation of aerosols during parturition of infected animals, or from the dust
of contaminated premises. European-level surveillance data are incomplete, but
in the last 10 years the overall trend appears to be rather stable with the
rate varying between 0.2 and 0.5 cases per 100 000. In 2005, 958 cases were reported by 21 countries. Germany and France reported the
highest incidence rates (0.49 per 100 000 and 0.48 per 100 000,
respectively). This is a typically under-reported disease due to its unspecific
Leptospirosis is a zoonotic disease with a wide clinical
spectrum, caused by Leptospira bacteria. The death rate is low, but increases with
advancing age and may reach 20% or more. Humans acquire the disease by
occupational or recreational contact with water, soil or other material
contaminated with the urine of infected animals. Infection in humans may follow
direct or indirect exposure to an infected animal’s urine or contaminated fresh
The overall incidence was stable in the EU during the
period 1995–2004, ranging from 0.1 to 0.22 cases per 100 000. The lowest
number of cases in recent years (687) was reported in 2004. France continues to
report a high number of cases, partly related to higher incidence in its
overseas departments. In 2005, 900 cases were reported by 24 countries, with
Estonia (0.82 per 100 000) followed by France (0.77 per 100 000)
reporting the highest incidence.
Anthrax is a zoonotic disease caused by the bacterium Bacillus anthracis. Reservoirs are usually
domestic and wild herbivores, and the spores can survive in the environment for
decades. Anthrax is endemic in some regions in the world, including southern
and eastern Europe. Humans become infected directly or indirectly from infected
animals. Control measures include the correct disposal of animal carcasses,
correct disinfection, decontamination and disposal of contaminated materials
and the environment. The use of suitable protective equipment and vaccination
of exposed susceptible animals and humans at occupational risk is required.
Vaccine is limited to occupational, military and laboratory staff. B. anthracis has been recorded as a
biological warfare agent since 1941.
Over the last 10 years, the overall incidence has been
stable. Twenty-seven countries reported a total of 250 cases throughout the
period (though only 24 countries reported for the whole 10-year period). The
most cases were reported by Spain (65%), followed by Greece (14%). In 2005, 21
countries reported just 10 cases.
West Nile fever
West Nile virus (WNV) is related to other viruses causing
encephalitis in humans. WNV is maintained in a cycle of wild birds and
mosquitoes. Humans are mainly infected through mosquito bites, although
infection through organ transplantation and blood transfusion has been
documented, as has trans-placental transmission from mother to child. Since a
first large outbreak in Romania in 1996, WNV infection has become recognised as
a major cause of public health concern in Europe. No treatment or vaccine is
currently available, and the main preventive measure is to minimise the risk of
mosquito bites, using mosquito repellent and protective clothing when outdoors.
In the past 10 years, indigenous WNV outbreaks have been
documented in the Czech Republic (1997) and France (2003)
affecting five and seven cases respectively. In addition, sporadic imported
cases have been reported in several European countries. The origin of infection
of most imported cases is the USA, where an increasing number of infections
have been reported since 1999.
Rabies is a disease caused by a rhabdovirus. It is mainly
a disease of animals and it occurs worldwide in warm-blooded mammals. The
transmission normally occurs through a bite from, or direct contact with saliva
of, an infected animal. The disease is fatal as soon as typical symptoms
appear. Prevention is possible by vaccination (before or after exposure).
Preventive veterinary measures include proper vaccination of cats and dogs.
Oral vaccinations to wild animals have proven effective in preventing the
spread of disease within wild animal populations. In the last 10 years no more
than seven cases per year were reported across the EU (total 21 cases). In
2005, five cases of rabies were reported by 22 countries; four of them from
Germany and one from the UK. There is a risk of re-introduction of rabies in
the EU via travelling or by the cross-border movements of infected animals.
Malaria is caused by the parasite Plasmodium, and is transmitted to
humans by mosquitoes. During the 20th century, malaria was eradicated from many
temperate areas, including the whole of the EU. As a result, the disease is now
essentially limited to tropical countries. The potential for malaria
re-introduction in countries where it has been eradicated is of growing concern
partly due to global climate change, as the malaria vectors are still present
in previously endemic areas, including Europe. ‘Airport malaria’ is sometimes
reported in relation to the inadvertent transport of infected mosquitoes from
endemic areas. Due to the large number of imported cases in Europe, malaria
surveillance is focused on travellers’ health.
Since 1995, France has accounted for a large proportion of
the imported malaria cases to Europe, mainly through its close ties with
several African, highly endemic, countries. Over the period, the overall
incidence rates have ranged from 1.45 to 2.27 per 100 000 per year, with a
steady decrease since 2000 (Figure 6.8).
6.8. Malaria trends in Europe
In 2005, 4 306 malaria cases were reported by 26 countries
(France not reporting). The favourable trend in recent years contrasts with the
increasing numbers of malaria seen in endemic countries. The fact that the
trend of malaria cases in returning travellers is in decline despite the
ever-growing numbers of Europeans travelling, suggests that travel prophylaxis
recommendations are being applied with increasing success. Still, the risk for
travellers to highly endemic areas remains significant.
Viral haemorrhagic fevers
Only those infections for which cases were reported in
returning European travellers, or which have been identified as a threat in
2005, are discussed here below. The quality and availability of data on VHF
differ from country to country. Some Member States’ annual reports document
data on VHF in general, some on virus-specific infections, while others do not
report VHF at all.
Dengue fever is endemic in Asia, the Pacific, the Caribbean, the
Americas and Africa. Humans are infected with Dengue virus through mosquito
bites. Current evidence indicates that repeated infection increases the risk of
the more serious Dengue haemorrhagic fever (DHF). In several Asian countries,
DHF has become a leading cause of morbidity and death, mainly in children.
Imported cases of Dengue fever are not uncommon, and in recent years Germany
has reported annually some 120–220 cases, the UK around 200–250 cases, and
Belgium and Sweden 25–60 cases. According to available data, no cases of DHF
were reported in 2005.
Lassa fever is endemic to West Africa. Rats are the reservoir of lassa
virus; humans become infected through contact with their excreta. While about
80% of infections are asymptomatic, the remaining patients develop severe
multi-system disease and up to 15% of the hospitalised cases may die.
Individual short papers in Eurosurveillance reported on a total of five
imported cases of Lassa fever in Europe in the past five years: two cases in
the UK from Sierra Leone (2000 and 2003), one case in the Netherlands in 2000,
also from Sierra Leone, and two cases in Germany in 2000 from Ghana or Côte
d’Ivoire and Nigeria. No cases were reported in 2005.
Crimean-Congo haemorrhagic fever (CCHF) is endemic in
several countries of Africa, the European continent and Asia. The virus is
transmitted to humans through the bites of ticks. There is no specific
treatment or vaccine available, and up to 30% of patients may die. In recent
years, outbreaks have been reported in Turkey, Kosovo and Albania. Eurosurveillance reported one imported
case of CCHF in the UK, in a traveller returning from Zimbabwe. No cases were
reported in 2005.
Ebola and Marburg haemorrhagic fevers are caused by the
ebolavirus and marburgvirus respectively, both belonging to the same
filoviridae family. Both are rare diseases, but have
potentially high death rates. Transmission of the viruses occurs from person to
person through close contact with blood or body fluids. No treatment or vaccine
is available for either disease. No Ebola or Marburg haemorrhagic fever cases
have been reported in Europe in the past 10 years.
Yellow fever virus (YFV) has caused
large epidemics in Africa and in the Americas, and is endemic in some tropical
areas of these regions. The virus is transmitted through bites of mosquitoes,
which also represent the reservoir for the virus. No specific treatment is
available for yellow fever, but prevention is possible
through administration of a highly effective vaccine.
Yellow fever has not caused any
outbreaks in Europe for more than a century. Only sporadic cases have been
reported in travellers returning from endemic regions. In the last 10 years,
one case was reported by Germany in 1999 (imported from Côte d’Ivoire), one
from Belgium in 2001 (imported from Gambia), four from the UK in 1998, 2001 and
2005, and two cases from Ireland in 1998 and in 1999 (but there is no
information on the source country of the UK and Irish cases).
In Europe no human plague cases have been reported for a
long time. Given the severity of the disease and its clinical characteristics,
it is unlikely that cases have been missed. Though relatively rare, the disease
has a worldwide distribution and in the most recent years, a growing number of
cases have been reported to the WHO. Presently, its only implication for
European health systems is to counsel international travellers and be prepared
to diagnose and treat the disease in returning travellers.