– Source:As of 17 June 2025, there have been over 4,000 confirmed cases of mpox and 25 deaths in Sierra Leone, raising the possibility that the virus will spread to neighbouring countries and spark a larger outbreak throughout the densely populated region of west Africa. Cases in Sierra Leone appear to be spreading from person to person, mainly among young men and women.
The Conversation Africa asked Jia Kangbai, an infectious-diseases epidemiologist at Njala University in Freetown, what’s behind the upsurge and how it can be stopped.
What is mpox and how is it transmitted?
Mpox (formerly monkeypox) is a disease caused by the mpox virus. It is a member of the Orthopoxvirus genus. Other members of this genus include small pox and chicken pox. Initially, close physical contact with an infected person was the recognised mode of contracting the virus. With the emergence of various subclades (Clade 1a and 1b, Clade 2a and 2b) of MPXV, sexual transmission of mpox has been documented in several studies.
What’s behind the recent outbreak in Sierra Leone?
The index case for the current mpox outbreak in Sierra Leone is a young man with a documented immunocompromised condition who had gone to the northern town of Lungi in December 2024 to spend Christmas Holiday with his wife. Two days after arrival in Lungi he had unprotected sex with one of the female hotel workers and later developed high fever, muscle and body pains, and swollen lymph nodes. He was later transferred to the capital Freetown where he was diagnosed positive for mpox. He was then admitted at the Connaught Hospital, Freetown, where he was successfully treated.
Sierra Leone’s international airport is located at Lungi. The town is also bustling with international tourists. It is possible that the current outbreak was imported from West Africa; it is also possible that cryptic MPXV transmission has been ongoing in Sierra Leone. Cryptic transmission is a situation when the virus is circulating within a population in low levels so much so that when there is an outbreak it is difficult to identify the source.
In our current study in Sierra Leone, we are running genomic sequencing on specimen obtained from this index case to know the source of the mpox outbreak.
This is a laboratory method used to determine the entire genetic makeup of a specific organism or cell type.
This method can be used to find changes in areas of the genome. These changes may help scientists understand how specific diseases form. Results of genomic sequencing may also be used to diagnose and treat disease.
How worried should Sierra Leoneans be about mpox?
Sierra Leoneans are visibly worried by the increasing number of mpox cases and deaths that have been recorded within four months of active mpox case surveillance. More worrying now for most Sierra Leoneans is the increasing number of commercial sex workers and people with multiple sex partners who are self-reporting for mpox.
Most of the mpox cases in Sierra Leone belong to these sub-populations. This implies that for an effective containment of the mpox outbreak in Sierra Leone special attention needs to be paid to these sub-populations.
What emergency measures need to be put in place to stem the spread?
The emergency measures put in place by the National Public Health Agency include:
targeted vaccination of at-risk population
active surveillance
contact tracing
quarantine, and
effective risk communication including the sharing of critical health information to empower individuals make informed and positive decisions about their safety and personal health
The effectiveness of these measures is being challenged because of the lack of resources. As of 17 June, there have been over 4000 confirmed cases and 25 deaths, with most patients recovering. But the number of mpox testing sites nationwide is very limited. During outbreaks with such dynamics, time is crucial. With few mpox testing sites it implies that the time it takes to process samples to releasing lab results (turn around time) is going to be very long especially in this case when we are dealing with a population of over 8 million people that are scattered all over.
How high is the risk of a regional spillover?
The West Africa sub region should be worried about a spillover. The cultures of the people in West Africa are identical, indicating a common ancestry. Additionally, there is a huge trade and trafficking of both human and goods across the sub region which makes the exporting of mpox cases easy.
Liberia, Guinea and Sierra Leone are so interconnected in diverse areas to an extent that anything that affects one country will affect the rest. We saw in December 2013 when Ebola started in Guinea, it quickly spread to Sierra Leone, Liberia and other non-African countries.
As of early June 2025 Liberia had recorded 69 mpox cases while there has been no reported mpox case for Guinea. Ghana had reported 98 as at 16 June.
Some strategies neighbouring countries can implement include heightened cross-border surveillance at their various borders and to conduct test for suspected and probable mpox cases. Additionally, within their countries they can embark on active case surveillance and contact tracing.
Jia B. Kangbai does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
By Jia B. Kangbai, Senior lecturer, Njala University
