Chapter 9

9.1 Comparing theoretical statements of the previous chapters with the empirical data of the Aids problem

In chapter eight we illustrated the COMPRAM problem handling method with the example of the Aids problem. In this chapter we will compare some of the theoretical statements made in the previous chapters, especially chapters two, three and seven, with the handling of a complex interdisciplinary societal problem in reality, in this case the Aids problem. Then we will illustrate the discussion begun in chapter three[1] on the relation between reality and the models used for predicting the future with an example of a system dynamic model of (a part of) the Aids problem: the spreading of the virus through the population. This is an illustration of research question two.

9.1 Comparing theoretical statements with the empirical data of the Aids problem

In this section we compare statements from the previous chapters with empirical data related to the Aids problem.

Some situations can be present for a long time, before they are recognized as a problem, or at least before they are recognized by a large group of people (section 7.1.1);

Before a problem can be handled, it must be recognized as a problem. This means awareness that there is a problem (section 2.4).

Looking back to the beginning of the Aids problem one realizes that long before Aids was recognized as a special disease there were persons who had already died of the disease. As early as 1979 it is certain that the disease caused the death of a Swedish doctor[2] working in Africa and of some young men in California (USA). But it took two more years, until June 1981 before AIDS[3] was recognized as a specific disease and with specific problems (Shilts, 1987, p. 68).

Taking into account the fact that the incubation time of the AIDS disease is from three to over ten years, one mayrealizes how the disease could be easily spread without anyone being aware of it. In this case not being aware is very dangerous. HIV infected people infected many other persons without realizing it.

There must be some signs that something is amiss, that there is a problem, before the problem handling can begin (section 3.3.1.).

The disease was discovered in the USA rather by coincidence. A certain medicine was needed for curing a specific kind of pneumonia. The use of medicine had to be ordered by the Centers for Disease Control in the USA, which registers the use of special medicines. On average this medicine is asked for three times a year. Suddenly the demand for this medicine increased ten fold, causing a very alert female clerk to realize that something strange was going on. She made a few enquiries and realized that a new disease was the cause of the new illness (Shilts, 1987, p. 55).

Now that we are aware of Aids it is easier to register some of the data related to Aids and by doing it this way follow, more or less, the progress of the virus through the population.

The assumption behind the idea of problem finding is that the sooner one is aware of the problem, the sooner the problem can be anticipated, the more chance there is to interfere in order to prevent the problem from becoming too severe and causing too much trouble (section 3.1.1).

In the early days of the Aids problem in the beginning of the eighties, after realizing what this disease was and how it could be spread, the idea was that early awareness could make a difference in handling the problem (Shilts, 1987; Kramer, 1989). In some of the literature about Aids and in many television documentaries, it is suggested that awareness in time could have prevented the Aids problem from growing so large, both in the USA and in Europe.

It is indeed very important to recognize future problems in time, when there is still a possibility of preventing the problem or of preventing the problem from becoming worse with relatively little effort. However, this statement mainly applies to an infectious disease that is easy to recognize and against which other people can easily be protected and against which people are willing to protect themselves and others. By 'easily protected' we mean by means of a vaccination, as in the case of polio, for instance, or by changing behavior as in the case of diphtheria by using clean water. In the case of infection by means of transfusion, knowing this beforehand would have made a difference concerning the number of HIV infected people by medical activities. When looking at the medical side of the disease, infection by surgery and transfusions, we see that knowing in time would have saved many lives. However, even after knowing that the infection could be spread through transfusions, because of economic benefits and indifference, even in countries such as France and Germany people were infected by contaminated blood[4].

However, in the case of a sexually transmitted disease we may wonder whether awareness of the problem in time could have prevented the spread of the disease. As we have seen, there is no prevention by vaccination, no secondary or tertiary prevention either and prevention through the use of condoms is at least problematic (Vroome, 1994). Taking into account what was said earlier about using condoms and knowing humanity with its lies, persuasion, incest, rape, differences in power, we know how hard it is to change behavior (Vroome, 1994) and we have our doubts, that the disease could have been prevented from spreading by sexual contact[5]. Not every person is willing or able to take the necessary precautions to prevent infection.

Another factor that complicates this is that many people are not aware of being infected and are a potential danger when it comes to infecting others.

Another argument against the notion that foreknowledge could have prevented the spread of the virus through the population is the situation in Thailand. Thailand is an example of a large population that was infected after a great deal of knowledge was available. The population of Thailand was hardly infected at the time that knowledge of this disease was disseminated in 1985 (Chin, 1990). Now a huge number of people are infected or are going to be infected[6]. Looking at the means of prevention[7], we are no longer sure that in this particular case being aware of the danger on time would have prevented the spread of the infection or would have slowed it down significantly[8]. When we consider the sometimes reluctant behavior of, for instance, the American government[9] towards education and prevention, we are not sure that knowing on time in itself would ever be sufficient to protect the population. We are convinced that in this case it takes more than awareness. However, awareness is a conditio sine qua non.

Awareness of the problem is still a central point, as in education. People tend to forget, to diminish the effect, to trivialize matters, to adopt an attitude of 'it can not hurt me' or a fatalistic approach. Because almost all sexual activities take place in private they lack the overt control which is possible with much other behavior. Sexual activities involve power differences, primary lust (Freud, 1901) and secret meetings, which are very hard to control from the outside.

Awareness of the problem is not constant. At the beginning of the Aids period between 1980-1984, the disease was not taken very seriously. Then, suddenly it was taken very seriously, and now again, when the first very serious predictions seems to have been overestimated, people tend once again to take it less seriously (Groen, 1993).

When there are problems found for which no adequate interventions are available, it can happen that not knowing the problem in advance can be better than knowing ( section 3.1.1).

Awareness on an individual scale can be different. When one is aware of having a disease that can be cured if there is help available in time, awareness at an early stage would obviously be preferable. However, with HIV infection, not knowing may be preferrable to knowing. Knowing oneself to be HIV positive is a terrible thing[10].

There is a tension between individual knowledge of being HIV infected and societal policy towards the Aids problem. Some of the medical researchers, especially epidemiologists, would like to have reliable data about the prevalence of HIV through the population. However, this is, as indicated above, not in the interest of the individual. The policy in the Netherlands about testing antibodies (TwK, 1989) is that it is forbidden to test antibodies without the permission of the individual. It is also not advised to take a test because of the psychological consequences, except in some specific cases as for instance pregnancy[11].

Sometimes a problem may have already been there for some time before it is noticed by someone or before it is put on the political agenda (section 2.4)[12].

It not always easy to convince policy makers to invest in a problem that is not yet manifest (section 2.4).

It took until December 1990 before the national health care system in the Netherlands was willing to recognize the special position of HIV infected women. At that time, compared with men, only a few women seemed to be infected. It was hard to convince the policy makers that even although there are only a small number of women infected, there should be special education for women and special research for HIV infected women (Bureau Women and AIDS[13], 1990).

Not all problems are everyone's problems. The same issue can be a problem for one group, while at the same time it is not a problem at all for another group, although people can disagree about this (section 2.5).

With regard to complex interdisciplinary societal problems, those for whom it is a problem, 'the victims' of the problem, are often not the same people who are (held) responsible for handling the problem (section 2.5).

The question of for whom something is a problem, relates a person, group, an organization or a society with a problem (section 2.5).

Describing the Aids problem written from the point of view of the victim often emphasizes the political unwillingness of people who are in power to handle the problem adequately (Shilts, 1987; Kramer, 1989). Among the first victims of the virus in the western industrialized world were many young homosexual sexually active men in the USA, mainly concentrated in Los Angeles, San Francisco and in New York at the end of the seventies and early eighties (Shilts, 1987; Kramer, 1989). This group had just discovered (homo) sexual freedom and were enjoying this freedom, among other things, by having sexual intercourse with many other men. Because of the homosexual backlash in the USA, a part of this group was politically well organized (Shiltz, 1987, p. 3-102). When it was recognized that their group had a great chance of being infected with a deadly infectious disease, they used their level of political organization to form action groups to force the government to do something about the problem, to initiate a medical research program and to sponsor education about the group they represented (Shilts, 1987; Kramer, 1989). Now, in many western, indistrialized countries, it is regarded as a governmental problem[14]. In their article Meyer, Molema & Jansen (1990) observe that within five years one hundred million of people will be infected with the Aids virus (Aids and Arc patients, seropositives). This observation has resulted in an intensive research program.

Whether a problem is urgent or not is not only an objective matter. It can also depend on a person's view or position (section 2.2).

Personal goals of the Aids patients are not always in line with the commercial goals of the drug companies or with the goals of the medical scientist. Some pharmaceutical plants have other interests than the HIV-patients. The pharmaceutical industries want to make money whereas patients want to be cured[15]. For instance, in the beginning, the price of AZT was so high that only very wealthy patients could afford it. There have been many fights by action groups in the USA (Act Up) and in the Netherlands (The organization Fight for Life) against the government and the pharmaceutical industries in orderd to have drugs accepted, or paid for by the insurance company, before the drugs were legally acceptable (Shilts, 1987; Kramer, 1989; Monet, 1989). It is clear that Aids patients do not have time to wait until all medicines have been carefully tested. From scientific point of view the opinion can be different regarding the view of Meyer et al. (1990).

Urgent problems need direct intervention, which demands a special approach compared to problems that are not so urgent (section 2.2).

Active homosexual groups in New York and San Francisco were of the opinion that the government should act more accurately on the Aids problem.

When the government failed to do these things the pressure groups thought they should act themselves. The action group later became a permanent pressure group also in other countries. This group put pressure on the government to take the Aids problem seriously, to organize special care for patients, to allocate research funds for it and to prevent the blame being put on the infected. The pressure groups were very well organized and had some success, although the government under the Reagan regime was unwilling to do a great deal. As a result many social, medical, legal support groups were set up. Medical support for medical pressure to find a cure (Fight for life), political support groups (Act Up[16]), legal support for those who had lost their jobs (and income) because of the disease, social support (the buddy project[17] is a well known example, as are the HIV positive bars[18] in the Netherlands) (Shilts, 1987; Kramer, 1989).

The problem definition..... is closely related to the interventions. ..... Defining a problem as a domain problem means, by definition, that one has the idea that the solution is within the domain or in a certain part of a domain, one narrows the handling space to that domain. Often too narrow a scope inhibits people from finding a good 'solution' for the problem. Defining the problem too narrowly can be one of the major causes for not being able to handle the problem fruitful (section 3.2.9).

A complex interdisciplinary societal problem can seldom be handled fruitfully when one defines the problem too narrowly.

Many interdisciplinary societal problems are defined as mono-disciplinary problems.

After narrowing the scope, by looking for interventions, the scope should be broadened again.

A too narrow or a mistaken definition can lead to a too restricted or incorrect handling of the problem. At the beginning of the Aids problem, Aids was defined in the USA as a homosexual[19] disease[20] called Grid[21]: Gay Related Immune Deficiency. Defining the problem this way had a special effect on the research and, according to many authors, on the development of the disease (Shilts, 1987). Defining the AIDS problem as a homosexual disease and as a homosexual problem in a puritanical society like the USA caused a great deal of trouble that could probably have been avoided.

For instance, a great deal of American scientific research is only possible by special funding from the federal government, the state, commercial companies or foundations. Initially, the government regarded special funding for research on a homosexual disease as unacceptable to the voters. Companies did not want their names linked with homosexuality. The consequence was that the funding of research for what was regarded as new medical phenomenon and social problem was, in the beginning, scarce (Shilts, 1987).

as a problem of developing countries. Sometimes a combination can be found, such as Aids as disease for homosexual and black people. Because Aids is often defined as a phenomenon of fringe groups, it had for a long time no high priority on the research agenda[22].

Aids is a global problem, although some governments have treated it for a long time as a local problem.

This was done, for instance, by the former USSR, who denied the existence of Aids patients, and in Japan. Some people try to keep the disease away by closing the borders to those who are HIV infected[23] or by putting them in special camps (Cuba and Sweden).

Because prevention fails, some changes are now being found, mainly in primary prevention such as in education[24].

In the Netherlands considerable attention goes to the special education of specific target groups, like children between the age of 12 - 14 who are educated in schools about safe sex, homosexual men[25], prostitutes, intravenous drug users[26] etc.

In the Netherlands as early as 1985 a multi-disciplinary team, consisting of medical specialists, legal practitioners and social workers, discussed the Aids problem (NCAB). However, it took until 1988 before a patient, who had the disease, was taken into the team as an expert[27].

Not everybody has the general benefit in mind in handling the problem hidden agendas.

The French blood transfusion scandal[28] at end of 1985 and the beginning of 1986, was based on economic motives and 'honour'. The French government, the ministry of Health Care, did not want to use the blood treatment developed in the USA, but preferred to wait for their own blood treatment. This treatment was not available intil early 1986. As a result of this policy, many hemophiliac patients were 'unnecessarily' infected. Another example of putting their own goal first instead of general goals was the conflic between De Gallo and Montagnier, Aids researchers, about who had discovered the HIV. This conflict lasted from 1983 until 1993, a conflict in which honor, money and even a Nobel price were involved. No matter what can be said about this affair, it has unnecessarily occupied the (co-)workers of two well-known research institutes, the institute of De Gallo and that of Montagnier (The Plague; Natuur en Techniek). The more recent blood scandal in Germany[29], also shows that not everybody has the optimal handling of the Aids problem in mind, with the main benefit being for all.

Knowing how a problem can be solved does not mean that the problem will be solved.

There may be many reasons, financial, political or practical, as to why a problem whose answer is known is not solved or handled.

Defining the problem will not automatically mean that the problem can be solved. Although some parts of a problem can be defined clearly, some major points and relations are known, it can still be very difficult to solve the problem. Even knowing where to look for a solution or knowing what kind of interventions are necessary, it still can be very difficult to solve the problem.

Although knowing were to search for prevention, for instance, by developing a vaccine in case of HIV, finding the solution is very difficult.

The inhabitants of an area in downtown Amsterdam with many intravenous drug users complain to the municipal government about inconvenience and the HIV infected needles discarted on the streets. The 'solution' of the municipal government was to close the needle exchange shop after nine o'clock in the evening. However, the shop was part of the needle exchange project (Cohen, 1990) which was meant to avoid needle sharing and this way avoid the spreading of the virus. This 'solution' for one group thus became a problem for the other group.

Meadows has developed a game for the World Health Organization called 'Aids Response' (Meadows, 1989). This game is based on a model of the Aids problem in Africa using a system dynamic modelling software to see what the effect of policy making is. In this game, several interventions can be tried in order to see the effect of financing on the development of the problem and the spreading of the HIV. To put in some realistic constraints the players have a limited amount of money with which they pay for interventions. This game gives an opportunity to realize what the consequences of certain kinds of policy making and interventions can be on the handling of the problem.

Not only in a game are scenarios used to predict the future development of a complex system, but also in real life (Jager, 1993).

Problem handling does not always occur rationally. It can also happen by a mixture of trial and error and rationality (Meijer et al., 1990a). The development of pharmaca that decrease or stop the replication of the virus takes place at random as well as the result of rational argumentation. Some of the most promising anti-HIV interventions, such as DDI and AZT, are found 'at random' in routine screening. Meyer et al. say of this way of research that these findings are

The rational way is based on domain knowledge, specially the knowledge of the virus-host interaction (Meijer et al., 1990a).

Until now[30] the Aids problem has been defined mainly as a medical problem. Much of the research attention has gone to medical research into a vaccine, preventing a person from getting infected and HIV interventions, in combination with research on HIV prevalence among homosexual men and intravenous drug users, and into the search for medicines to provide a cure. Although the report of the Dutch Program Committee for Aids Research (1992) indicates that it uses

"A multidisciplinary approach encompassing epidemiology, social science and virology, immunology and clinical research has contributed to improved knowledge and understanding of the various aspects of HIV-1[31] infection." (1992, p. 10)

most of the research that was financed, coordinated or integrated in this program of the Dutch Program Committee for Aids Research was in, or closely related to, the medical field and the homo studies group of the University of Amsterdam and the University of Utrecht. The Amsterdam cohort studies, the Amsterdam cohort study among homosexual men and the Amsterdam cohort study among intravenous drug users, are coordinated by the Municipal Health Service Amsterdam in co-operation with the department of Public Health and Environment. The other cohort study is performed under the auspicies of the University of Amsterdam together with the laboratory for experimental and clinical immunology. Although the word 'interdisciplinary' is used in the right sense, the multidisciplinarity that is reflected involved only some disciplines, such as the medical discipline and the social science and homo studies, the latter in particular studies the topic of sexual behavior. Over the last seven years the Amsterdam study has been directed particularly concerned to the following topics:

- prevalence and incidence HIV-1 infection (insight into the introduction and the spread of the virus in the male homosexual population in the Netherlands)

- factors responsible for transmission and changes in sexual behavior (this provided a basis for primary prevention)

- natural history of HIV-1 infection (recognition of pathogenetic steps in progression to Aids)

The cohort study on HIV infection and Aids among intravenous drug users was a collaborative effort of the department of Public Health and Environment of the Municipal Health Service of Amsterdam, the department of Virology of the Academic Medical Center of the University of Amsterdam and the department of Clinical Viro-Immunology of the Central Laboratory of the Netherlands Red Cross Blood Transfusion Service and Laboratory for Experimental and Clinical Immunology.

- to study the prevalence and incidence of HIV infection and AIDS in relation to (changes in ) drug use and sexual behavior

Other medical related research is conducted by the Netherlands Organization for Applied Scientific Research (TNO), the Institute for Applied Radiobiology and Immunology. Department of Infectious Diseases (research on pneumocystis carinii pneumonia), at the Catholic University of Nijmegen. Department of Infectious Diseases, at the Leiden University Hospital, also conducts medical related research.

Studies performed within this cooperation that are not medical include the study on processes and explanatory factors of preventive behavior concerning Aids and other sexual transmitted diseases, especially condom use, in heterosexual contacts performed by the Department of Communication Sciences, at the Catholic University of Nijmegen.

Non-medical research carried out by the Netherlands Institute of Social Sexological Research (NISSO) is concerned with the social-sexual infrastructure of possible HIV-transmission. Research is conducted by the Department of Health Education, at the University of Limburg, on the development, implementation and evaluation of AIDS-education for high-school students (Schaalma, 1991).

A research program on the psychosocial aspects of Aids beginning with a psychosocial and epidemiological survey among hemophilia patients and their spouses, on health-seeking behavior of people with HIV/Aids, on the surveillance of HIV infections among drug users outside Amsterdam and on social comparison and the threat of Aids among married and cohabiting heterosexuals with a positive intention towards extramarital contacts (Dutch Program Committee for Aids Research of the Dutch Advisory Council on Health Research, 1992).

"...the Dutch Program Committee for AIDS reseach presents this up to date survey of Dutch AIDS related research. Since 1988 almost all such research in the Netherlands has been stimulated and coordinated by this committee."

As indicated earlier the Aids problem in the Netherlands, between 1982 and 1992, was primarily defined as a medical problem. However, it seems that Aids is gradually being recognized as an interdisciplinary problem[32]. Even a very popular Dutch television station has devoted a whole week to broadcasting all kinds of special programs around the theme of the Aids problem. Here the Aids problem was presented as a complex interdisciplinary societal problem (RTL V, January, week four, 1994).

Although most of the money is put into medical research and most of the litarture is on the medical aspects of Aids[33], there are certain publications that highlight other aspects of Aids, although these are often published in medical journals (Kastelein, 1989; Boer & Lagaaij, 1989; Bowles, 1989).

At, and shortly before, the international Aids conference of 1992[34] there were for the first time attempts to approach Aids as a complex interdisciplinary societal problem. This was mainly because of the disappointing results of the medical science[35]. A number of the published articles also reflect non-medical aspects of the Aids problem dealing with seropositivity, Aids and labor[36] (Roscam Abbing, 1989), Arbo Raad (1988), HIV infection of employees, in relation to absenteeism (Ven, 1989). Aids and insurances (Raadt, 1989), financing aid (Simons, 1989), Aids and family doctors (Wigersma, 1989), Aids and district nurses (Eggenkamp, 1989; Hoeksema, 1989), Aids and hospital policy (Dutree, 1989), Aids and nursing homes (Keizer, 1989) as well as psychosocial aspects of Aids (Rooijen, 1989), registration and estimate of costs (Druten & Jager, 1991), about hospital costs (Borleffs & Jager, 1989; Borleffs, Jager, Poos, Dijkgraaf, Geels, Vrehen & Schrijvers, 1990), monitoring hospital activities, the costs of care and quality of life related to AIDS and other HIV infection (Dijkgraaf, Jong, Poos, Borleffs & Jager, 1992), and prognoses and economic consequences (Jager & Postma, 1989a).

As stated earlier, the AIDS problem is now considered in most countries as a concern for governmental policy, although it took a long time before each country was willing to subscribe to this idea.

How should this problem be handled? It is very important to recognize that, although the number of people in the western world suffering from the disease at this moment seems to be relatively small, the problem has the potential to become very large. Aids is an outstanding example of a problem that starts on a small scale, but increases in size and already has become a very dangerous and far-reaching problem in some areas of the world and for some populations. This problem should be approached as a global complex interdisciplinary societal problem, not as a local problem or as a mono disciplinary problem.

An international team of experts should regularly come together to analyze and define the problem, and discuss the consequences of the Aids problem in all areas of the society, and from that renewed definition suggest interventions, construct and evaluate scenarios, and implement and evaluate the interventions in real life. In handling this kind of problems, all governments, (inter) national health institutes and economic institutes, such as the World Bank, should work together to fight the problem.

The special topic we discuss here is the relation between reality and scenarios.

Models made of complex interdisciplinary societal problems contain so much uncertainty that scenarios based on these models also contain a large degree of uncertainty. This makes it very difficult to make reliable predictions based on these scenarios for the future development of the problem (section 3.4.4).

We can make a simulation model of the spreading of HIV through the population as an example for discussing a system dynamic based scenario. For this discussion, we selected the same demarcated scope and aggregation level as discussed in chapter eight, the spreading of the virus through the population of the sexually active (young) homosexual men with many changing partners. The geographical scope is Amsterdam, the time scope is between 1984 and 1994. The main levels in this model are the number of people that are healthy, the number of people that are HIV positive, the number of people that have Aids, the number of people who have died of Aids[37].

The use of system dynamic models for future prediction is criticized, in chapter three, from three viewpoints, from the point of view of the theoretical ideas of complex interdisciplinary societal problem theory, from the view of system theory and from the view of chaos theory. In this chapter we connect some of the criticism of these three views to data concerning the Aids problem.

Criticism from the theoretical ideas of complex interdisciplinary societal problems

In constructing the model in relation with reality, one can begin by filling the main levels with the number of healthy people, the number of the HIV positives, the number of the people with Aids and the number of the people who died of Aids, or one can start with one infected person. However, even in filling these four relatively simple levels in this model one encounters many difficulties concerning the real data[38]. Let us take one level as an example of how difficult it is to know the real data, for instance the number of people who have died of Aids. It is legally obligatory to register people who have died of Aids. The Dutch census data (CBS)[39] registers the number of men and women that have Aids as cause of death on their death certificate. Although the CBS is a very reliable (semi) governmental institute the numbers are not as trustworthy as they seem. The numbers are however only the number of patients who had the word Aids at their death certificate. There are many reasons for not registering Aids on a persons death certificate[40] (Jager, Postma, van den Boom, Reinking, Borleffs, Heisterkamp, van Druten & E.J. Ruitenberg, 1989b; Jager, Postma, Leidl, Majnoni d'Intignano & Baert, 1990b).

Another reasons can be plain ignorance: the physician who fills in the death certificate may just not be aware of, or familiar with, what the disease Aids looks like. Another reason can be that the person is unknown to the one who fills in the death certificate and when the diagnosis of Aids is unknown it is not always possible to see that the cause of death was Aids. This often happens with anonymous drug deaths. Another reason can be that although there are indications that the person has Aids, because Aids is closely connected to homosexual behavior, the family prefers to avoid social abuse by stating that the cause of death was cancer, or pneumonia which might be immediately correct, though it is not the underlying cause of death[41]. Dying of Aids can also be registered under the name of one of the diseases the person actually died of.

The numbers of people in the homosexual male population in Amsterdam who are healthy (which, in this case, means, not infected with the virus) and who are infected is not easy to estimate because there is no registration of HIV infected persons in The Netherlands. Even if testing were possible[42], the data would be uncertain because in the first six months of the infection the virus does not show up in the test. Even to estimate the whole population would be difficult. Then, of course, looking at such a population one should always be aware that the boundaries are only artificially drawn. Who belongs to this particular population? Some men in this population will have sexual contact with people from other populations such as with drug users, with bisexual men and with heterosexual women. Making distinctions between populations is also difficult. Druten, Jager, Heisterkamp, Poos, Coutinho, Dijkgraaf, Reintjes & Ruitenberg (1990) make a distinction between three main risk groups: promiscuous home/bisexual men (two levels of promiscuity), intravenous drug users (men and women) and promiscuous heterosexual men and women (Dangerfield & Robert, 1990a; McCormick, 1989).

Estimating how many people in this population are involved in unsafe behavior is difficult to estimate[43]. What the effect is of their unsafe behavior is even more difficult to estimate, and depends on how many people of their reference population[44] are infected with HIV. It is also quite uncertain what the effect of education on safe and unsafe behavior will be to the people at all times, in all cases under all circumstances. We may have some indication of the extent to which protection is used by the registration of venereal diseases, since it is obligatory to register the venereal diseases. These numbers give an indication of the incidence of unsafe sexual intercourse. When a venerious disease could be transmitted the HIV could also be transmitted depending on whether the person who infected the other is HIV positive or not.

Discussing quantitative models of Aids at the RIVM shortly before the international Aids conference in Amsterdam in 1992[45] one realized that many quantitative data that are required for estimating of the number of people that are infected or that have Aids are very unprecise and very uncertain. Even the simple quantitative data as to how many people are infected and how many people have died of Aids are impossible to obtain. In 'Aids impact and assessment', on modeling and scenario analysis, (Jager & Ruitenberg, 1992) concentrate on the following subjects:

- data about quality of AIDS/HIV prevalence data used in models (Dondero & Wilson, 1992; Lavoie, Lumey, Couturier, von der Fuhr, Ancelle-Park & Brunet, 1992; Bailey, 1992, Gill & Tillett, 1992; Heisterkamp, Downs & Poos, 1992)

- the scope and the applications of the models (Laar & Pickering, 1992; Heesterbeek, 1992; Druten, Poos, Hendriks & Jager, 1992; Haan & Dijkgraaf, 1992; Leagergren, 1992)

- linking models with sociological information (Schnabel & Boom, 1992; Gilmore, 1992; Aron & Wileyto, 1992; Zessen & van Griensven, 1992; Beckmann, 1992; Reinking, van den Boom, Postma & Jager, 1992; Gonzalez, Myrtveit & Vavik, 1992)

- linking models with economic information (Duckett, 1992; Leidl, Postma, Poos, Majnoni d'Intignano, Jager & Bart, 1992; Wiggers & Bergsma, 1992; Dijkgraaf, Jong, Poos, Borleffs & Jager, 1992). Data can be found in the results of the workshop[46] on quantitive assessment of the impact of the human immuno deficiency virus (HIV) and the acquired immune deficiency syndrome (Aids) on society. Jager & Ruitenberg (1992)[47]report the following concerning forecasting in general:

- environmental uncertainty leads to a high demand for forecasts but the conditions for producing forecasts are poor;

- when the trend is relatively constant, prognoses ar 'simple' to produce but, understandably, then there is little demand for them."

On forecasting the development of Aids, as a complex interdisciplinary societal problem, authors say:

"There definitely is much uncertainty with respect to HIV and Aids. To name a few: prevalence and incidence in different populations, incubation time, infectiousness, survival time, biomedical progress, economic costs, social consequences. In short, HIV-infection matches the profile of a problem where scenario analysis is in high demand, but forecasting is difficult." (Jager & Ruitenberg, 1992, p. xvii)

Another critique of the use of system dynamic models for future prediction is that this assumes that the system can be seen as a unity separated from the rest of the world. It is only an artificial separation and should be handled accordingly. The environment of the system will influence the system. The isolated model should always be seen in the context of the model of the whole problem and the environment[48].

A third criticism comes from chaos theory. As explained earlier, chaos theory emphasizes unpredictability. Analyzing empirical epidemiological data shows that in an epidemic fluctuations and chaotic periods interchange.

Proof of this statement comes from Metz (1990) who studied the course of measles, mumps, German measles, small pox and scarlet fever among children reviewing data from more than fifty years. Two investigations in this field, that of Olsen, Truty and Schaffer (1988), on the data related to these diseases reported in Copenhagen in the period of 1927-1968, and that of Grossman (1980) on the data from New York and Baltimore in the period of 1928-1970, show that periods of high rates of infected children alternate with periods of low rates. Metz (1990) also shows that data about measles in England and Wales show a two year cycle, in which high rates also alternate with low rates. These kinds of infectious diseases sometimes have a cyclic course and sometimes a rather whimsical and irregular course. The spreading of infectious diseases through a population can be illustrated on the basis of a model of limited growth.

This is a model which is also known as the logistic formula, according to the model of Verhulst or the model of limited growth:

This model shows the number of new born rabbits in a closed population. In this formula, X is the percentage of the population infected with the disease, a is a constant, a measure for the infectiousness of the disease, and t a certain time period. This model can also be used as a model to illustrate the spread of an infectious disease in a closed population (DeTombe, 1992).

The course of an epidemic can also be illustrated with the logistic or Verhulst formula. In the field of epidemiology there is only an epidemic as a is (much) greater than 1, otherwise the spread of the disease will decrease slowly. When a has a value between 1 and 3, the graphic representation of this formula through time will move to a limit 1-1/a. This means that there will be an epidemic, but the increase in the number of people who get the disease each month will slow down until there is a constant number of people that are infected each period. However when the value of a is between 3 and 3,44 there will be an epidemic in the sense of what is called period doubling which converge after several periods to alternately two limits in the graph. On this point the prediction of the value will result from the formula is already uncertain (it can be two values). The uncertainty increases when the value of a is between 3,44 and 3,57 (then there are four limit values) and when a is > 3,57 and < 4 there is a chaotic development. When there is a chaotic development one is able to describe the range of outcomes but is unable to predict which outcome there will be.

Thus, even when a system can be so carefully and exactly described as in this simple formula, which includes a feedback loop, there is uncertainty in the outcome in the predictability of the system. Eventhough we have here an algorithm[49], there is no unique solution (when a is > 4 the result is undefined). This illustration of a formula of non-linearity shows that, depending on the values of the variable, unpredictability can occur.

The non-linear aspects of models can also be seen in the models of the spread of HIV through the population. To illustrate how non-linearity influences the prognoses of a system we take an example of the field of epidemiology.

Even the very small and simple model that we use to illustrate the spreading of the HIV through the population[50] has some non-linear feedback loops. The unpredictability of this model can be easily illustrated with the well known example of the population growth, for instance of rabbits. As HIV which is also an infectious disease, one may wonder whether the spread of the infection among the population has irregular or even chaotic progress. In order to answer this question we should first of all answer the question of whether or not HIV is spread among the population as an epidemic in the sense of the epidemic field or not. Therefore we have to know the value of a. In the calculations of Metz (1990) the value of a is calculated on the bais of 50 years of data, and on an

infectious disease with a cycle of four? weeks. Although HIV can be traced back to 1959, real data on the disease begin around 1980. Knowing that the mean run time (duration of the disease) is from 3 to 14 years, this means that we only have data from one or two periods of the disease. Based on this amount of data, we can say nothing about the course of the HIV infection.

In this last discussion we isolated the infection as a component of the medical domain of the Aids problem which was in fact rather artificial. However, the spread of infection through the population is influenced by more things than just the infectiousness of the disease itself, depending also on the influence of new populations, the influence of education etc. This makes the spread of the disease even more unpredictable. It is now possible to realize that as far as the whole Aids problem is concerned, which includes all kind of phenomena of different domains, it will be very difficult to estimate and forecast the way in which this problem will affect people and the world in all areas of life.

For complex interdisciplinary societal problems there will always be a large degree of uncertainty in the model on the effect of the interventions and in the scenarios. Even when the selection of interventions and the comparison of scenarios is carefully done with as much knowledge, tools, methodological support and human effort available, one should be very carefully to use scenarios for policy making (DeTombe , 1992).

"Although criticism is frequently levelled at scientific forecasting, the demand for the prediction of the future is actually increasig. We have the paradoxical situation that decision makers claim that forecasting has little relevance but all the time they request increasinly comprehensive forecasts on ever more complex issues. This growing demand has a simple explanation, which lies in the increasing interdependency, interlinkage and complexity of our world due to the breakneck pace of scientific and technological change. The result is that the environment of any human action is developing even more rapidly and thus becoming less predictable. More and more forecasting is becoming an instrument for countering the growing uncertainty." (Jager & Ruitenberg, 1992, p. xvii)

In this chapter we have illustrated some theoretical statements from the previous chapters with examples of the Aids problem as a complex interdisciplinary societal problem. In 1994 the Aids is still seen by many persons as a disease of others: homosexuals, intravenous drug users, prostitutes, poor black people. Most of the persons see Aids as a disease of fringe groups which does not concern them. In many cases it will be possible only to a certain extent to make an empirical model that fits reality (DeTombe, 1993).

We have shown that with an empirical model of a complex interdisciplinary societal problem, even if we only regard a part of the model, in this case a part of the medical domain, filling that empirical model with real data is very difficult and often even impossible. Unpredictability can occur because of white and blind spots in the model, missing or uncertain data and non-lineairity of the model. In discussing this we emphasized some social aspects and some medical aspects. Although we have seen that these aspects can only be divided artificially, we connected some of the statements from the previous chapters to empirical statements on the Aids problem. The examples we have given are mainly of the medical and the social aspects, especially the male homosexual and the intravenous drug user aspects, because the bulk of literature on Aids focuses mainly on these aspects. However, one should not conclude from these examples that Aids is only an interdisciplinary problem only concerning these two domains. What we said about Aids as a complex interdisciplinary societal problem in chapter eight makes it abundantly clear that the Aids problem involves many domains.

This is the reason for using these kinds of models for the future prediction of complex interdisciplinary societal problems. They must be carried out with the greatest possible care, and not used merely as a vehicle for politicians to justify their politics.

[1] See section 3.4.4.

[2] Dr Grethe Rask.

[3] June 5, 1981, Morbidity and Mortality Weekly Report by the Centers for Disease in the USA.

[4] In many countries even now blood is not screened for contamination blood. For instance in Egypt, in parts of East-Europe or in parts of Africa.

[5] See the report of Kramer (1989) on this subject

[6] The Bangkok Journal of 1990 estimates the number of people that will be HIV infected by the year 2000 at about 6 million.

[7] Section 8.2.

[8] In western society there has been an increase in infections through medical activities.

[9] For instance, in the USA the government pretends that teenagers do not have sex under the age of 16. Eastern-European countries and Japan for a long time stated that they had no Aids patients, claiming therefore that warningsagainst the disease were not necessary.

[10] However, this policy means that every person should behave towards a partner as if they were infected, thus preventing the possibility of infection.

[11] Research is done for instance on blood analysis on HIV prevalence (Dees, 1988). Policy, human rights and blood analysis on HIV antibodies (Frankena & de Graaf, 1990).

[12] See also what is said before about awareness of Aids (Shilts, 1987; Kramer, 1989).

[13] In Dutch Buro Vrouwen en Aids.

[14] In the Netherlands Aids is now also a concern of the government (Dees,1988; Broekhuizen, 1989; Staatssecretaris, 1988).

[15] These things are not always in line.

[16] See Kramer (1989).

[17] The goal of the buddy project is to give non-medical help to Aids patients. To help them with their shopping, to accompany them to the doctor, to wash them when they are no longer able to do this. It is basically a volunteer project. It is a very successful project mainly among homosexual men, for allocating support for those persons who have no family (who is willing) to take care for them.

[18] A HIV positive bar is a place where only hiv positive people, mostly men, get together. Because many infected homosexual men were isolated among their own group of homosexuals, they organized a place for themselves to meet and to talk.

[19] Even though it was already known that the same kind of virus was causing deaths in Africa among many heterosexuals.

[20] Because of the definition of the Aids problem as a homosexual disease people who did not define themselves as homosexuals had the idea that they were immune to this disease.

[21] Until the end of 1982.

[22] The Netherlands VROM diseases priorities, internal report in 1993. Defining something as a problem of 'the other' ensures that it has a lower status than it would have had if the person who should handle the problem sees this as a problem directly concerning himself or herself (Beauvoir, 1949/1978).

[23] As is the case in the USA. This was the reason the International Aids conference in 1992 was held in Amsterdam instead of in Boston, where it was originally intended.

[24] These terms of primary prevention are used differently from the medical term prevention as we discussed in chapter three.

[25] Education on safe sexual behavior between homosexual men seems to be very successful, although there are some indications that homosexual men are becoming more careless on this matter. An indication of this new development can be found in the increase of venereal diseases in this population. Venereal diseases have to be reported. Where a venereal disease is transmitted it is possible to transmit the HIV virus too.

[26] A very successful project the 'needle exchange' project in the Netherlands (Cohen, 1990). There are some indications, however that the project was less successful in the beginning of the nineties.

[27] This happened after special intervention by Queen Beatrix of the Netherlands.

[28] The French government refused to treat the blood sera given to haemophilia patients, with the blood treatment equipment developed in the USA, because they were waiting for the development of their own blood treatment, which at that moment was incomplete, though they were aware that there was a reasonable chance that the blood was infected.

[29] A commercial institute used unchecked plasma for transfusion in German hospitals even as late as 1993.

[30] May 1994.

[31] HIV-1 is the kind of HIV that is active in the western world. The African variant is called HIV-2.

[32] Although this is not reflected in the allocation of research funding.

[33] See also chapter eight.

[34] Organized by the University of Amsterdam and Harvard University.

[35] Lecture by prof. E.J. Ruitenberg, at the IVth EC Workshop on Quantitative Analyses of AIDS Modelling, Impact, Assessment, Forecasting and Scenario-analysis at Bilthoven July 16-18 1992, organized by the National Institute of Public Health and Environmental Protection (RIVM).

[36] The titles of these articles have been summarized and translated. Most of the articles are in Dutch.

[37] See the system dynamic model of the spreading of HIV.

[38] Especially in some parts of the USA and in the United Kingdom people and their family are sometimes socially isolated because they have (a family member with) Aids (The Plage; Intimate Contact; Shilts, 1987).

[39] Central Bureau of Statistics of the Netherlands.

[40] See discussion at the IVth EC Workshop on Quantitative Analyses of AIDS Modelling, Impact, Assessment, Forecasting and Scenario-analysis. Bilthoven, July 16-18 1992, organized by the National Institute of Public Health and Environmental Protection (RIVM), see also McCormick (1989).

[41] See discussions about Aids data at the IVth EC Workshop on Quantitative Analyses of AIDS Modelling, Impact, Assessment, Forecasting and Scenario-analysis. Bilthoven, July 16-18 1992, organized by the National Institute of Public Health and Environmental Protection (RIVM).

[42] See the discussion in this chapter.

[43] For instance, it is supposed that the chance of contracting the virus when engaging in anal intercourse is about 100%, because with this kind of sexual intercourse the blood of one partner often comes into contact with the sperm of the other partner.

[44] The reference population is the population with whom, in this case, they have sexual intercourse.

[45] the IVth EC Workshop on Quantitative Analyses of AIDS Modelling, Impact, Assessment, Forecasting and Scenario-analysis, Bilthoven, July 16-18, 1992, organized by the National Institute of Public Health and Environmental Protection (RIVM).

[46] The workshop was held at the National Institute of Public Health and Environmental Protection (RIVM), Bilthoven, The Netherlands, 18-20 December 1989.

[47] Future scenarios and models, Dijkgraaf, Gubbels & van Griensven (1989). See also Steering Committee on Future Health Scenarios (1992).

[48] See also the discussion of the participants after the first system dynamic model of epidemiology, in chapter eight.

[49] See chapter three.

[50] See figure 14 in chapter eight.

Chair Operational Research Euro Working Group

Complex Societal Problems