The monkeypox epidemic is a zoonotic disease that broke out in many African countries and has been a matter of concern for decades. The disease has been highly contagious and has caused widespread panic among the locals. Surprisingly though, the spread of the disease has slowed down over the years. A new theory has emerged amid the scientific community that Mpox, as it is called, could potentially be waning due to sexual networks among the people living in the affected regions. In this article, we’ll explore the curious case of Mpox and the “sexual network” theory that is currently causing a stir in the medical world.
Belgian researchers have presented a theory at the European Congress of Clinical Microbiology & Infectious Diseases that the recent outbreak of mpox may have ended due to “network immunity”. The epidemic saw over 85,000 cases worldwide and men who have sex with men were the most affected. Cases rose rapidly from May 2022 before starting to decline a few months later, and the reasons for the decline remain unclear. However, Dr Christophe Van Dijck and his colleagues hypothesized that the epidemic waned due to a change in the behaviour of the population at risk, with core members of the sexual network being infected with mpox first, peripheral members later. This generated “network immunity” that halted the epidemic.
During the outbreak, the rapid rise in cases in May 2022 was likely caused by efficient viral transmission during sexual contact between individuals with high partner turnover in a dense and geographically extended sexual network. Insufficient knowledge of the disease as well as asymptomatic and pre-symptomatic transmission may have enhanced disease spreading. However, in most countries, including Belgium, the decline in mpox cases had already started before a substantial proportion of the population at risk had been vaccinated.
The researchers used two sets of data collected at the Institute of Tropical Medicine in 2022. The first set of data was from a questionnaire filled in at diagnosis by individuals with mpox. Among the 155 individuals with mpox, 95.5% were gay and bisexual men who have sex with men (GBMSM), and the median number of sexual partners in the previous three weeks was two. The second set of data was from a questionnaire filled in by men who were attending a clinic at the Institute for pre-exposure prophylaxis (PrEP, a drug that reduces the risk of getting HIV). Among 1,322 PrEP-users, 99.6% were GBMSM, of whom 55.9% visited the clinic repeatedly in 2022. At first visit, the median number of sexual partners in the previous three months was five. Core-group PrEP-users reported consistently more partners than non-core-group PrEP-users. The number of partners in both the core and non-core-groups increased throughout 2022.
The decline in the number of partners reported by individuals diagnosed with mpox towards the end of the epidemic suggests a change in behaviour of the population at risk. However, this was not corroborated by data from the PrEP population, where the overall number of sexual partners increased over time. Therefore, the researchers proposed an alternative hypothesis: core members of the sexual network were infected with mpox first, peripheral members later. Infection-induced immunity of the individuals at the core of the sexual network generated “network immunity” which halted the epidemic. They are currently working on serological and modelling studies to establish whether this hypothesis is true.
In conclusion, we need to be aware that future mpox outbreaks may occur if the “network immunity” is disturbed, for example by waning immunity of infected or vaccinated persons or when previously uninfected, peripheral members of the sexual network become more sexually active. More research is needed to fully understand the potential of “network immunity” to lead to the end of future epidemics.
In conclusion, the curious case of Mpox and the “sexual network” theory sheds light on the complexities of disease spread and eradication. While medical breakthroughs and public health interventions played a significant role in containing the monkeypox epidemic, the behavioral changes within the community and the implementation of safe sexual practices cannot be ignored. The Mpox outbreak serves as a reminder that disease outbreaks can only be effectively controlled if we take a comprehensive approach that encompasses medical, behavioral, and social factors. It is important that we continue to study and learn from infectious disease outbreaks like this to better prepare for and prevent future epidemics.
