A Systematic Review of 5110 Cases of Monkeypox: What Has Changed Between 1970 and 2022?

The recent monkeypox (MPVX) outbreak has been characterized by an unprecedented increase in cases, unlike any other outbreaks in the past. The disease pattern and transmissibility are also different from previous outbreaks. This systematic review aimed to evaluate whether the current outbreak has significant contrasting features from the previous ones, necessitating changes in prevention and control guidelines. A thorough literature search related to MPVX infection was performed on the online databases PubMed, Google Scholar, and ScienceDirect using appropriate keywords "MPVX", "men who have sex with men (MSM)", "transmission", and "smallpox vaccination", for choosing relevant articles from the inception of MPVX in 1970 to August 31, 2022. We identified 5110 cases of MPVX, documented in 63 articles on MPVX. We discovered that the median age of MPVX infection has slowly increased since its inception, and currently, it is more common in adults. Compared to previous outbreaks, a significantly greater male preponderance is witnessed in the current outbreak. Only 238 (4.65%) out of the 5110 evaluated patients were vaccinated with the smallpox vaccine in our review. There were 107 mortalities, most of which were children below the age of 10 years. Out of the 1534 cases identified in 2022, 1134 (73.92%) patients admitted that they had been involved in sexual relations within the last 21 days (MSM/gay/bisexual). We found that in contrast to previous outbreaks, human-to-human transmission is more common in this outbreak, with most cases having no link with endemic countries. There are evolving traits and undetected transmission modes of MPVX infection that require new disease mitigation strategies.