Dutch Public Health Status and Forecast 2006

High population density, intensive contact with animals and frequent travel were major contributory factors in the SARS epidemic of 2003. The first cases of the ‘mysterious form of pneumonia’ subsequently classified as SARS were reported in November 2002 in the southern Chinese province of Guangdong. In 2003, the epidemic took on a new dimension, when ten guests at a hotel in Hong Kong were infected, before moving on to trigger local epidemics in Toronto, Singapore and Hanoi. Eventually, the illness spread to nearly thirty countries, where more than eight thousand people contracted the disease, resulting in approximately eight hundred deaths. The economic and social consequences were considerable. The global cost, mainly in the form of reduced investment in Asia and reduced air travel (due partly to a decline in tourism), was estimated at between 33 and 140 billion dollars.

The cause of the illness is infection by a corona virus not known before 2003. After an incubation period of two to ten days, infected individuals develop fever, headaches and muscle pain and often diarrhoea. Most go on to develop pneumonia within a further few days, necessitating ventilation in some cases. The disease leads to death mainly among elderly patients. The exact origin of the SARS virus is still not known, but it almost certainly came from an animal reservoir.

SARS did not reach the Netherlands. Nevertheless, protocols and contingency plans were drawn up in preparation for a possible outbreak.

Information about the SARS epidemic was communicated to the public and to health workers using the media and the internet in new ways. Under the supervision of the WHO, researchers and medical practitioners treating SARS patients exchanged data, so that scientists all over the world were able to help look for the cause and develop treatment strategies. By similar channels travel restrictions and other control measures were introduced. Eventually, the epidemic’s spread was halted by the combination of communication via modern media, high-grade research and measures known to be effective since the middle ages: the isolation of patients and quarantining of possibly infected individuals.

Since December 2003, various countries have witnessed outbreaks of avian influenza in poultry and other birds, caused by the dangerous H5N1 subtype of the avian influenza-A virus. The outbreaks in poultry very probably resulted from infection by migrating waterfowl. Contact with the virus leads to high levels of mortality among chickens, ducks and turkeys. The infection is occasionally observed in mammals, such as tigers and cats. A number of outbreaks have occurred in Europe. Furthermore, the avian influenza-A virus can be transmitted from birds to humans. Worldwide, more than two hundred human cases have been reported, and approximately half of them ended in fatality.

The most serious threat posed by this avian influenza epidemic is not occasional deaths of the kind so far seen, but the possibility that the virus will adapt to the human host, enabling person-to-person transmission. A virus that had mutated in this way would quickly be able to spread around the world. The consequences of such a pandemic could be very grave. It is estimated that, even in the most favourable scenario, an avian flu pandemic could kill between two and 7.4 million people; in less favourable scenarios, the number could be even greater. The social and economic consequences could be even more disastrous.

Considerable effort is being made to develop a vaccine against the H5N1 virus, but it is not presently possible to predict when it will be widely available. In order to nevertheless be ready for a influenza pandemic, the Dutch government decided in 2005 to build up a stock of five million doses antiviral agent. In addition, contingency plans are under development, setting out what should be done in the event of a pandemic. It is hoped that these measures would help to minimize the death toll and the social disruption caused by any future pandemic.

In 2003, the Netherlands was affected by an extensive avian influenza epidemic. This episode also involved an influenza A-virus, but of the subtype H7N7. Despite control measures, such as the slaughter of livestock on farms adjacent to those with infected birds, the disease spread rapidly to poultry farms in various parts of the Netherlands. More than 250 farms reported infections and more than 25 million animals were slaughtered. In some cases, the virus was passed on to humans. In 336 cases, the infection caused conjunctivitis (eye inflammation), and in eighty-five individuals it induced flu-like symptoms. One vet died from pneumonia caused by influenza A H7N7. The epidemic continued for three months.

Anthrax is an infectious disease caused by the bacterium Bacillus anthracis. The bacterium creates spores that can survive in the ground for decades. In humans, the disease can take three forms. In order of increasing seriousness, these are:

1. Cutaneous or skin anthrax: infection via broken skin leads to the development of an ulcer with a black crust.

2. Gastrointestinal anthrax: consumption of spore-contaminated food can lead to a fatal gastrointestinal infection.

3. Inhalation anthrax: the inhalation of spores leads to serious and usually fatal pneumonia.

In October 2001, anthrax spores were maliciously distributed by post in the USA. The strain used proved to originate from one of the laboratories in that country where research into B. anthracis is conducted. The events in America prompted the Netherlands’ National Infectious Disease Control Coordination Structure to rewrite its protocol on B. anthracis. The protocol now includes a section setting out how suspect post should be dealt with in the Netherlands, the diagnosis procedure and what should be done with people who have been exposed to anthrax. In autumn 2001, a total of 858 letters and packages were examined for anthrax spores. Although the numbers have since declined, suspect packages have continued to be submitted for testing; up to 1 January 2006, the total number of items involved was 1,335. However, no post contaminated with anthrax spores has so far been found either in the Netherlands or elsewhere in Europe.

Smallpox is a highly contagious viral illness, which killed countless millions of people in the last millennium alone.

This disease is characterised by vesicles on the skin and mucous membranes. Human-to-human transmission of the virus is usually via the respiratory tract, from where infected droplets are expelled by coughing. However, infection can also result from contact with puss from vesicles or with vesicle crusts. Following a series of successful vaccination campaigns, smallpox was eventually eradicated in 1977.

The human smallpox virus is preserved in just two laboratories in the world, one in the USA, the other in Soviet Union. Some commentators have expressed fears that, with the collapse of the Soviet Union, the virus could fall into the hands of a terrorist organization and be used for bioterrorism.

In the Netherlands, concerns about the possible reintroduction of smallpox have led to various precautionary measures being taken. In October 2001, the Minister of Health, Welfare and Sport ordered the production of sufficient cowpox vaccine to enable the vaccination of the entire Dutch population. In addition, contingency plans have been developed. Fortunately, it has not (so far) proved necessary to put the plans into action.

MRSA is a major cause of infection both in hospitals and in the community. MRSA infections have been reported all over the world. In Europe, a clear north-south gradient is apparent, with the prevalence of infections lowest in the north. The percentage of S. Aureus strains isolated in the Netherlands that prove to be MRSA is relatively low, but gradually increasing.

The strains that cause MRSA infection outside hospitals, known as community-acquired MRSA (CA-MRSA), have genes for the Panton-Valentine leukocidin (PVL) toxin and cause serious skin infections and sometimes a fatal pneumonia in otherwise healthy and often young people. The prevalence of CA-MRSA appears to be rising around the world. In the Netherlands, approximately 10% of the MRSA isolates submitted to the RIVM prove to be positive for the PVL genes; some of these are CA-MRSA.

Following the discovery that several members of two families of pig farmers were infected with MRSA, the RIVM and the Food and Consumer Product Safety Authority investigated the occurrence of MRSA in pigs. Approximately 40% of 540 randomly selected porkers were found to be carrying a ‘non-classifiable’ form of MRSA. Furthermore, when a group of twenty-six pig farmers at a regional meeting were tested, six of them were found to be carrying the bacterium. The implications of these findings have yet to be investigated.

Both community-acquired and hospital-acquired MRSA presently remains treatable. However, MRSA infections would become untreatable if the pathogen assumed resistance-plasmids from vancomycin-resistant enterococci (vancomycin-resistant Staphylococcus aureus, VRSA). Such enterococci are a normal component of the intestinal flora of humans and animals. Vancomycin-resistant enterococci (VRE) are low-virulence bacteria, but are insensitive to many antibiotics. Globally, VRSA is a very minor problem and has yet to be detected in the Netherlands.

In recent years, the incidence of tuberculosis (TB) has been reasonably stable in the Netherlands: about 1,400 cases a year are reported. Most of these cases involve people arriving in the country from abroad. Thus, TB is increasingly an imported disease. The tuberculosis bacterium is described as multidrug-resistant if it is insensitive to two or more types of medication. People with MDR-TB are less likely to recover from infection. On average, the treatment of MDR-TB takes one and a half to two years and is extremely complex and expensive.

MDR-TB is a serious problem mainly in Eastern European countries and in the former Soviet Union, where tuberculosis patients are ten times as likely to have a multidrug-resistant infection as those elsewhere. In the Netherlands, MDR-TB is presently a minor problem (see table 3.10). The country’s first outbreak of the multidrug-resistant form of the disease occurred in 2004: an Eastern European tuberculosis patient infected nine other people, two of whom developed pulmonary tuberculosis.

In various countries (USA, Canada and the UK), an increase has been observed since 2002 in the number of hospital patients suffering Clostridium difficile infections with serious outcomes. The Clostridium difficile bacterium can cause diarrhoea and serious intestinal inflammations. A type of C. difficile rarely seen prior to 2002 and known as type O27 often appears to be the cause. Infection with this type leads to serious illness and also appears to respond less well to the usual treatment.

Outbreaks of hospital-acquired infection caused by C. difficile are difficult to control and necessitate numerous countermeasures. In 2005, type O27 was also discovered in a number of Dutch hospitals, leading to the introduction of special surveillance measures and the formulation of control guidelines.

In 2003, a previously little-known STD called rectal Lymphogranuloma venereum (LGV) was first observed in men with homosexual contacts. Most homosexual and bisexual men found to have LGV infections were also HIV-positive. The patients reported having had unprotected sexual relations, usually with casual partners, in other countries, such as Germany, the UK, Belgium and France.

Cases of rectal LGV were also reported in the USA and Canada. The outbreak of rectal LGV led to intensive surveillance and control measures, including information campaigns and action to warn the partners of infected men. By 1 January 2006, 178 cases of rectal LGV had been reported and it appeared that the epidemic had peaked. Nevertheless, cases are still being detected in considerable numbers in neighbouring countries, so it is important to remain alert in relation to this new illness.

Chlamydia is the most frequently diagnosed STD in the Netherlands. Many infections don’t lead to symptoms of illness, but transmission to sexual partners is nevertheless possible in such subclinical cases. In the longer term, complications can arise, such as reduced fertility or even infertility in women.

Chlamydia is found with approximately equal frequency in women and men. However, it is more common in certain ethnic groups. About two thirds of women diagnosed with chlamydia are less than twenty-five years old. Selective screening of sexually active people aged fifteen to twenty-nine is shortly to be started in urban areas.