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Epidemics and medical imaging

Rinckside 2021; 32,5: 13-15.


pidemics or, worse as in our recent case: pandemics, pose a great threat to hu­man­ity. They have claimed more lives than all the wars and na­tu­ral di­sasters in hist­ory com­bined. Many mil­lions of people fell vic­tim to the great plague out­breaks cen­turies ago, to cho­le­ra pan­de­mics or, at least during the last 500 years, in­fluen­za pan­demics that seem to ap­pear in 20- to 50-year cycles. De­spite great suc­ces­ses in me­di­cine, in­fect­ious di­seases con­tinue to claim millions of lives today.

The outbreak of Covid-19 has shown how quickly a virus can bring life in today's world to a standstill and threaten the existence of millions of people. The dedicated Special Exhibition: Epidemics — Curse of the Past, Threat to the Future at the Roemer-and-Pelizaeus-Museum in Hildesheim in Germany traces the history of epidemics through the centuries and offers a glimpse of the future. It is the biggest ever special exhibition on the topic — and was planned long before the outbreak of Covid.

The poster an­nounc­ing the exhi­bition reminds of medical imaging. Radiology is the inter­disciplinary cross­roads for most medical specia­lities, from trauma­tology to cardiology. There is one exception: usually, not too many high-technology examinations are requested by the infection wards. In radiology, therefore, there was not much contact with the specialists in infectious diseases, and often limited knowledge about these diseases exists among radiologists.

Anyhow, if physicians dealing with infectious patients want to refer one of them to radiology there is always trouble and discussion because, in contagious cases, the imaging facilities used have to be closed and disinfected after the examination. Usually today, these wards have their own mobile imaging systems allowing plain imaging of their patients.


RPM-Hildesheim

Exhibition at the Roemer- und Pelizaeus-Museum, Hil­des­heim (Ge­rmany): Seuchen. Fluch der Ver­gan­gen­heit — Be­droh­ung der Zu­kunft (Epi­de­mics. Curse of the past — threat to the fu­ture). 2 Octo­ber 2021 un­til 1 May 2021.

Rapidly after the outbreak of Covid-19 several thousand papers were published about diagnostic imaging of the disease — very often as non-reviewed preprints [1]. Getting an overview is nearly impossible. One helpful overview of nearly 5000 publications was published in the Cochrane Database of Systematic Reviews [2].

Imaging techniques, especially com­puted tomo­graphy and to a lesser ex­tent ultra­sound, play an import­ant role in dia­gnosis and treat­ment assess­ment of the disease.

A rewarding description of what a major French radiology center had to face when all of a sudden they were confronted by a tidal wave of Covid-19 cases was written by Robert Lavayssière [3].

"We had to cope with several different problems at the same time: staff absenteeism (colleagues who got sick or were confined to home due to potential contacts, closed schools, etc.), global fear of the unknown, problems of cancer patients in our cancer-focused center, lack of protective gear because the authorities gave priority to public hospitals, global unpreparedness, and the drastic reduction of overall activity, leading to potential financial problems …

"Thanks to the national and international publications and information campaigns, we have become quite aware of the Covid-19 CT features, but soon we had quite a lot of nontypical cases, including patients with extrathoracic findings or severe cases in young people."

For those practicing medicine in Europe, the worldwide extent of infectious diseases was difficult to imagine before Covid-19. In the late 19th century, or even as recent as eighty years ago, the situation was dif­fer­ent. In 1892, 21% of the German population died of infectious diseases, in 1920 13.6%. The figure dropped to 0.83% sixty years ago, and to 0.78% in 1987.

In the years before World War I, the slums of London and many other big cities all over Europe were characterized by dirt, drunkenness, terrible poverty, and exploitation. One in three infants died before reaching its first birthday. After the introduction of medical examinations at schools, it was reported that nearly 20% of the children were unfit to be taught because they suffered from worms or other infectious diseases.


Resurgence of Tuberculosis

Tuberculosis was one of the foremost and most feared killers. In a treatise on climatic health resorts published in the mid-nineteenth century, the author underlined that at least 25% of the customers of pharmacies suffered from phthisis, i.e. tuberculosis [4, 5]. The author recommended moving to Madeira as a possible remedy.

Improved sanitary and living conditions and better medicines — in particular antibiotics — developed after the First and Second World Wars changed this situation. In Europe and parts of North America the incidence of tuberculosis declined steadily from the 1930s until the 1980s.

Cavities in the lungs may form quite early in tuberculosis. Reading chest x-rays, looking for single cavities or diffuse spread, typically constituted a major, albeit rather boring, daily task for a radiologist still 60 years ago. Fluoroscopy and x-ray population screening became a household part of radiology between the 1930s and the late 1970s. At this time, finally, tuberculosis was considered almost eradicated in Europe. Although tuberculosis was no longer deemed a threat to mankind, the disease still remains a marker of poverty and social decline.

Today we once again see a rapid increase in tuberculosis, most dramatically in the big cities of the U.S.A. but also in France, Great Britain, Central and Northern Europe. Tuberculosis is primarily seen in immigrants but also connected to HIV infection. In one Northern European country, 5% of the immigrants proved positive for tuberculosis in the late 1970s; 25 yeards later that number has climbed to 40%. The worldwide situation looks even worse. The tuberculosis bacterium has infected at least 1.75 billion people; of the millions of people who die every year all over the world, some 2-5% die from tuberculosis. It is the leading killer among infectious diseases. In comparison, less than “only” 2% die from malaria.

As many other contagious diseases, most cases of tuberculosis occur in developing countries, as nowadays malaria does too. Overpopulation, lack of water and hygiene in many parts of the world, as well as the general absence of or the failure to realize health programs are the cause of the increased incidence of contagious diseases.

Travelling adds to the problem, but the single most important factor behind the resurgence of tuberculosis is the worldwide spread of AIDS, a disease that often accompanies tuberculosis infection and of which tuberculosis may well be the first sign.


Tropical Diseases

It should not be forgotten, however, that there are many tropical or "exotic" diseases. Among those that are almost unknown to Europeans but are not exclusive to the tropics is amoebiasis. Many radiologists are familiar with the name of the disease, but have you ever seen an amoeboma? When performing abdominal imaging it can look like a carcinoma constricting the colon.

The World Health Organization (WHO) estimates that some 200 million people, most of whom live in tropical and subtropical countries, are infected with bilharziasis, or schistosomiasis. This infectious water-borne disease is transmitted by snails carrying the parasitic flatworm that causes it. Once bilharziasis is established in an area, it is virtually impossible to eradicate — and the disease is on the rise in many regions of Africa.

As with tuberculosis, at least one quarter of the world’s population suffers from ascariasis. The roundworm ascaris is the most common cause of jaundice in children all over South America, Africa, and Asia.

The round dance of infectious diseases continues with echinococcosis, trypanosomiasis, typhoid, leprosy, and, of course, malaria. When I attended a course on tropical diseases as a medical student, the professor pointed out that actually most of these diseases are exotic rather than tropical — because they are exotic to us and extinguished in most of Europe. But malaria was found in England, Italy, southern Switzerland, even in the Baltic States not so long ago. The last epidemic in Germany was in a region in the north-east of the country in late summer 1946 — 6,000 cases within a month. Leprosy was also widespread all over Europe. Geographical names such as Rosenheim, a town close to Munich, are proof of it — the name has nothing to do with roses, as the local tourist board claims — but rather means “leprosarium”.


Role of Radiology

Let’s return to radiology: Although the diagnosis of infectious diseases is not a primary indication of diagnostic imaging in Europe, radiologists are increasingly performing examinations of immigrants and travellers returning from the tropics. Plain x-rays, ultrasound and other basic imaging examinations are helpful in primary diagnosis and follow-up. CT and MR imaging are useful in the diagnosis of a limited number of these diseases, such as cysticercosis, particularly if cerebral or spinal affections are being investigated.

Sometimes, when you read images with changes or lesions inexplicable to you — and without proper medical history on the referral sheet, you should think twice and ask the patient: “Have you been abroad?”.

Patients might not mention recent travels to the referring physician because they may not consider it pertinent. With many parasites or infections there is a delay before symptoms of the disease occur, and I have seen a number of cases where the radiologist directed the referring physician towards the diagnosis of a tropical disease.

In spite of this, radiography or other imaging methods are rarely mentioned under the heading of diagnostics in manuals or textbooks on tropical diseases, such as that written by Bell [6]. Physical examinations and laboratory tests remain the backbone of diagnostics. The major exception is again tuberculosis.

But new epidemics are also spreading as we have seen with the "novel" corona virus. According to WHO, several dozens new pathogenic agents have been discovered in recent years, among them the Ebola virus and new types of hepatitis. They might become a prominent health issue, even in Europe, because it appears that treatment with anti-viral durgs, and vaccination will become more and more difficult. Due to the increasing drug-resistance of some strains of bacteria, use of antibiotics might not prove successful.

Will there also be a role for radiology, especially high-technology radiology, in the diagnosis of these diseases? It seems unlikely. Exceptions might be in monitoring disease with CT or MR imaging, ultrasound or CT-guided biopsies, and interventional radiology, for instance in tuberculosis. However, just the enormous number of patients will be prohibitive for high-tech or even low-tech imaging.

It is always good to know more about the diseases we do not normally see, first, to be able to recognize them in case we happen to come across patients suffering from them, and second, not to be mentally stuck with the ordinary diseases we encounter every day. Just as common European diseases may be regarded as exotic in other parts of the world, those that Europeans call “exotic” are common elsewhere.



References

1. Rinck PA. Speech is silver, but silence is golden. Rinckside 2020; 31,6: 11-12.
2. Islam N, Ebrahimzadeh S, Salameh J-P, et al. Thoracic imaging tests for the diagnosis of Covid-19. Cochrane Database Syst Rev 2021, 16;3 (3): CD013639.
3. Lavayssière R. Hard truths from Covid-19 front line in Paris. Aunt Minnie Europe, 20 April 2020.
4. Schultze R: Die Insel Madeira. Aufenthalt der Kranken und Heilung der Tuberkulose daselbst. Enke Verlag: Stuttgart 1864.
5. Rinck PA. Kleine Geschichte der heilklimatischen Kurorte im Oberitalienischen Seengebiet. in: A Small Café. 2020.
6. Bell DR. Tropical medicine. 4th ed. Blackwell Scientific: Oxford 1995.



Citation: Rinck PA. Epidemics and medical imaging. Rinckside 2021; 32,5: 13-15.

An abridged digest version of this column was published as:
What's radiology's role when it comes to epidemics?
Aunt Minnie Europe. Maverinck. 21 September 2021.


Parts of this column were published earlier in: "Radiology and epidemics, new and old". Rinckside 1996; 7,1: 1-3.



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