Eskild Petersen | Professor Emeritus of Infectious Diseases, Institute for Clinical Medicine, Faculty of Health Science, Aarhus University, Denmark
EMJ had the pleasure of interviewing Eskild Petersen, Professor Emeritus of Infectious Diseases, Institute for Clinical Medicine, Faculty of Health Science, Aarhus University, Denmark, on his research in emerging infections.
You chair the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Emerging Infections Task Force, Basel, Switzerland. Please could you tell us about the key projects you have undertaken to date?
The purpose of the task force is to inform ESCMID members about emerging infections. This is important because most society members are either microbiologists or clinical infectious diseases physicians working in hospitals. Therefore, they are not screening or looking for emerging infections every day. Since January 2020, the principal focus has been major developments in COVID-19, such as the emergence of new variants and the use of vaccines. Now, we are becoming increasingly concerned about monkeypox. More recently, there has been news of a cholera outbreak in Mariupol in Southern Ukraine. This is not surprising given that the city has no running water or functioning sewage system. However, we still believe this is a situation people should be made aware of, especially because there are currently 7 million refugees from Ukraine all over Europe.
You recently chaired the ESCMID/Infectious Diseases Society of America (IDSA) joint web symposium on monkeypox. Please could you provide a brief overview of this event, and a summary of the key take-home messages?
Monkeypox was a great concern for the World Health Organization (WHO) when smallpox was eradicated in 1980. There were fears that the monkeypox virus would fill the epidemiological niche left by smallpox. This led to the introduction of an extensive surveillance programme for monkeypox in Africa between 1980 and 1987. During that 7 year period, the WHO did not observe an increase in monkeypox and so the surveillance programme was stopped. Since that time, we have seen smaller outbreaks. Although there have been previous cases in the UK, these were linked to people who had been traveling in West Africa.
Surprisingly, sexual activity is a major driver of the current monkeypox outbreak. There has also been unprecedented community transmission among men who have sex with men. As far as we know, the spread is primarily related to human behaviour rather than changes in the virus. Even so, we know from the HIV pandemic 40 years ago that it is difficult to change health-related behaviour. Therefore, I think that we will see continuous, low-level transmission of monkeypox.
As of 10th June, I saw that we had approximately 1,300 monkeypox cases but no fatal outcomes. In the second week of August, we passed more than 25,000 cases worldwide. In most cases, if you have a normal immune system, monkeypox is mild and resolves spontaneously within a few weeks and without treatment. Infection is much more severe if you are immunocompromised. This encompasses those who are infected with HIV but without proper treatment, transplant recipients, and people with autoimmune diseases who receive biological drugs.
Overall, I believe monkeypox is here to stay as a low-level and primarily sexually transmitted disease. The main dangers are for individuals with an impaired immune system.
How important do you believe the implementation of One Health approaches will be in responding to the current multi-country monkeypox outbreak?
A One Health approach is very important in many contexts. If we look at emerging infections over the past 70 years, 80% have been zoonotic diseases coming from animals and jumping into humans. With monkeypox, we know very little about the animal reservoir. However, we suspect small rodents harbour the virus. We also suspect that sporadic infections in West Africa are due to the consumption of bushmeat, whereby people kill wild animals and get blood on their fingers. They may then scratch their nose and in this way acquire the infection. Knowing the animal reservoir is essential in order to understand disease epidemiology, design control programmes that minimise contacts between humans and animals, and ultimately reduce the risk of zoonotic spillover.
Are there any atypical or perplexing aspects of the 2022 monkeypox outbreak that are of particular scientific, public health, or social concern?
Not that I know of. However, there is an ongoing discussion as to whether the virus has been circulating undetected for several years. For example, if you had a sore on your genitals that healed in 1–2 weeks and you were not particularly sick, it is possible that you had the disease but did not notice it.
One of the things that is different with the current outbreak is the availability of a vaccine. The smallpox vaccine has an efficacy of 85–90% against monkeypox. We also know that pre-exposure prophylaxis works well in certain groups. Therefore, it is not hard to imagine a scenario in which the vaccine is offered to gay and bisexual men who have a higher risk of exposure. This would be similar to offering pre-exposure prophylaxis for HIV prevention. I think that offering free vaccines to people with high exposure risk is a sensible approach and possibly the only way to stop the spread of monkeypox.
What do you believe to be the major knowledge gaps with respect to monkeypox?
It was a great surprise that monkeypox could be transmitted through sexual contact and could penetrate intact skin and mucous membranes to cause a systemic infection. The current outbreak also indicates that surveillance in Africa is suffering from resource problems. There must have been some sexually transmitted monkeypox infections in tropical Africa, Nigeria, or the Democratic Republic of Congo, where it is endemic. Yet this was never reported. The reason it was reported in Europe is because we have much tighter surveillance.
Even in Europe, there is a chance that monkeypox was spreading under the radar for years. Theoretically, a patient could have presented to the hospital with a genital lesion. The doctor might have collected samples for syphilis, herpes, gonorrhoea, and chlamydia testing, which would have come back negative. If the lesion then healed and the patient and doctor were satisfied, no additional investigations would have been carried out. This shows how easy it can be to miss things. If patients recover, healthcare professionals will often not pursue a clinical question any further. However, in some cases, this should be done.
Could you provide an outline of your 2021 research article, entitled ‘COVID-19 Pandemic: Lessons Learned From More Than a Century of Pandemics and Current Vaccine Development for Pandemic Control’?
One of the most important lessons is that vaccines are the most potent tool to control the pandemic. It was also impressive to see the rollout of efficient vaccines based on two platforms, the adenovirus platform and mRNA platform, in just 12 months. This was only possible because the platforms were already available. Indeed, the groups in Germany and Britain had worked with these two platforms for more than 10 years. Essentially, they were ready on the shelves. The companies then managed to run clinical trials in an amazingly short period of time. As a result, we were able to reduce the mortality and morbidity from COVID-19.
The main challenge is that the vaccines are based on the January 2020 strain. Since then, the virus has evolved to the point where it could evade vaccine-induced immunity. Now, Omicron BA.5 is circulating. Talking to a colleague in Portugal, I was informed that 90% of new Omicron cases there are caused by the BA.5 variant. They also have as many cases as they did in January and February, with as many people in hospital and intensive care. Initially, I did not think that Omicron BA.5 would spread throughout Northern Europe during the summer months. However, it looks as if this is precisely what is happening. Therefore, we desperately need a new generation booster vaccine that includes Omicron in addition to the ancestral virus from January 2020.
How will climate change impact the risk and burden of communicable diseases in Europe? What measures can governments and health systems adopt to contain climate-related outbreaks in the future?
The main impact, especially over the next few years, will be on diseases that are transmitted by insects. Examples include leishmania, which is transmitted by sand flies, and the chikungunya and West Nile viruses, which are transmitted by mosquitoes. Insect vectors will change their distribution in response to planetary warming. As vectors move into regions that previously were too cold, we will begin to see disease transmission in new areas. Currently, we do not have West Nile virus in Denmark. This is because mosquitos need an ambient temperature of 22 oC in order to transmit the disease from birds to humans. However, as it gets warmer, West Nile virus will creep upwards. Similarly, leishmania is spreading northwards to France and is now also found in the Po Valley in Italy. So, the changing distribution of vectors is the main concern associated with climatic change.