why monkey pox is increasing day by day. What is reason behind spreading disease

More than half of the monkeypox cases in the current outbreak may have been passed on to others before symptoms appeared, according to a new modelling study from the United Kingdom. The study, led by disease modellers from the UK's Health Safety Agency, contradicts current public health guidance on how monkeypox is spread. It also has important implications for how to limit outbreaks of infection, especially those that occur in homophily networks. The research is published in the medical journal The BMJ. Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, says the new study gets to the heart of a question that public health officials have been trying to answer for months: How exactly does the virus spread? Most of those who get it are children living in rural hunting villages. Much of what we know about the virus comes from these settings, where transmission occurs within families living in close proximity. In countries now experiencing outbreaks due to imported cases, almost all infected men are having homophily with other men, and the routes of transmission have changed. "With poxviruses in general, you tend to see transmission once symptoms develop," said Han, who was not involved in the study. "For several months, there's been a concern or a growing awareness that if you're talking about transmission in homophily networks, if there's any type of contact where presymptomatic transmission is possible, that's it," Transmission before people know they are infected helps explain the explosive growth of the outbreak before vaccination became widespread, Han says. This also suggests that the virus is likely to pass through homophily before a person has symptoms that they are aware of. The monkeypox virus has previously been detected in the semen and in anal swabs of infected men who had no symptoms. Before this study, doctors were aware that it was possible to shed the virus before symptoms appeared, "but we didn't know how common it was," said Dr. John Wartburg, an infectious disease specialist at the University of California, Berkeley School of Public Health. As of May 2022, more than 75,000 cases of monkeypox have been reported worldwide, with 99% of them in countries where the virus does not normally circulate, according to the US Centers for Disease Control and Prevention. The number of cases of monkeypox in the United States has dropped dramatically. As of October 2022, the seven-day average of new cases of monkeypox reported to the CDC is about 30 per day, down from a high of 446 cases per day in early August 2022. There have been 28,492 cases of monkeypox diagnosed in the US as of Wednesday, 2022, according to the CDC. This progress shows that public health efforts to raise awareness of the infection and encourage vaccination of high-risk individuals are working. But while the effort is paying off, public health officials say it's important to guard against complacency and misinformation about the disease so that it doesn't return. Currently, official advice states that people can transmit the infection only after they develop symptoms. As of Wednesday, 2022, the CDC website advises readers, for example, that "A person with monkeypox can spread it to others from the time symptoms appear until the rash has completely healed and a new layer of skin has formed. But that's not what epidemiologists found when examining contact tracing records from the current outbreak of monkeypox in the UK. As in the US, about 95% of recent cases of monkeypox in the UK were among men who had homophily with men. Most cases were reported after close homophily contact. For this study, researchers collected records of 2,746 cases of monkeypox in the United Kingdom identified from the start of their recent outbreak to August 1, 2022. From this larger set of records, they looked for cases with linked contacts where both people had infections that were confirmed by PCR tests and had recorded dates of onset of symptoms. They found 79 pairs of linked cases and contacts who had all the required information. From these records, they were able to determine a metric called the "serial interval," which is roughly the time between the onset of symptoms in a case and the onset of symptoms in the person they infected. From a separate subset of 54 people who filled out questionnaires, the researchers were able to pinpoint when they were exposed and when their symptoms first began to develop to calculate the incubation period of infection -- how long it takes for symptoms to develop after exposure. They found that the incubation period was sometimes longer than the window between the onset of symptoms in a case and their associated contact—a pattern explained when transmission occurs before symptoms. Overall, after the researchers adjusted their data to account for possible sources of bias, they found that the median serial interval between cases and contacts in the study was shorter than the median incubation period for infections, "indicating substantially greater presymptomatic transmission than previously thought," write the authors of the study. CNN reached out to the CDC with questions about whether the study might change its guidelines on monkeypox but did not receive a response by the deadline. The CDC doesn't usually comment on research it's not involved in, and public health agencies don't usually change their advice based on a single study. I hope soon "This requires confirmation by further studies but has implications for vaccine-based disease elimination strategies that should be seriously considered," said Dr. Bochum Kaiden Titans, who is an infectious disease specialist at Emory University. "What ratio of cases seems to be asymptomatic, and how much do these cases contribute to establishing new chains of transmission? "These are pressing questions that need answers," Tianjin told the nonprofit Science Media Center in a statement about the study.