The majority of mpox cases can't be tracked

As cases of mpox steadily increase across the African continent, some 68% of them don’t have an epidemiological link — meaning they’re popping up among people that health workers aren’t monitoring and who aren’t known to have been in contact with previously identified cases. “This is a major concern,” said Africa Centres for Disease Control and Prevention Director General Dr. Jean Kaseya during a press briefing, noting that there are concerning gaps in the continental response in areas of surveillance, contact tracing, and data collection. This year, there have been over 32,400 suspected cases — of which about 6,440 have been confirmed — and over 840 mpox deaths reported across the African continent. The majority of cases are in the Democratic Republic of Congo. It’s a good sign when new cases largely pop up in individuals under surveillance by health workers, said Dr. Ngashi Ngongo, Africa CDC’s lead on coordination of the continent’s mpox response. But when it's unclear how people contracted the virus, it's evidence of a problem. “That shows that your surveillance is not working, which is the reality in most of these countries,” Ngongo said. The goal is to monitor the contacts in at least 90% of cases. But, according to Africa CDC, health workers have tracked the contact of less than 4% of identified cases. Tracking transmission To effectively tackle this outbreak, responders must gain control over tracking how the disease is moving through communities from person to person — but that’s not currently happening. One reason is that testing of suspected cases is also insufficient — the overall testing rate in Africa is 49.5% of suspected cases, compared to a goal of at least 80%. There are a few reasons for this. African health workers don’t have access to a rapid test that would allow them to give patients their results quickly, Kaseya said. Most of the testing is happening in laboratories — where samples are sent for testing and it can take days for a patient to receive results. This makes it challenging to conduct surveillance at the local level because health workers don’t have the tools to rapidly identify cases within their communities. It also makes it challenging to contain the spread of the virus across national borders, because those at the border can’t test people such as truck drivers, one of the sources of its spread to new countries. And of the suspected cases tested by laboratories, only 40.2% are positive — but some of those could be false negatives.The low positivity rate among those tested suggests challenges in how the samples are collected, the ways in which samples are transported to laboratories, and analysis at the lab, Kaseya said. Most of the people collecting samples haven't been trained on what constitutes a quality specimen for testing for mpox, Ngongo said. DRC is also a logistically challenging country, with bad or nonexistent roads making it difficult to transport the samples. Due to this series of factors, Kaseya said the number of cases his agency reports is considered to be a significant underestimate. This includes the number of countries experiencing outbreaks. So far Africa CDC has recorded cases in 15 countries, but this may be an underrepresentation, Kaseya said. For example, Tanzania hasn’t officially declared a case, but several of its neighboring countries have. “Is it the reality or not, knowing that Tanzania is the neighbor of Burundi, Uganda, Kenya?” Kaseya asked. “We can also challenge, I think, if the surveillance system is really working, but officially today, we don't have cases in Tanzania.” Without easy access to testing, health practitioners are often left to use “case definitions” — assessing a patient's symptoms. But this method can be imprecise, as it can miss cases, or count suspected cases that are actually other diseases with similar symptoms — such as measles, chicken pox, and herpes. Instead of cases popping up in individuals that health workers have been tracking because they’ve been in contact with someone with mpox, health workers identify the vast majority of cases when people fall sick and seek care on their own. For example, an mpox case of clade 1b — the new strain that was first recorded in DRC last year — was recently reported in India in a person who had just been to the United Arab Emirates. Kaseya said Indian authorities told his agency that this person hadn’t been in contact with people from the African continent. “If this is the case, somehow we missed something,” Kaseya said. ‘Many unknowns’ While mpox has been present on the continent for decades, there are still a lot of unanswered questions about how this outbreak is unfolding, Kaseya said. For example, there are questions around the dynamics driving transmission, including why so many children are contracting the virus, Ngongo said. There’s also a need for more research around treatment options. Bavarian Nordic’s MVA-BN vaccine for mpox has been used in other jurisdictions, such as the United States, for several years. But it only recently received the World Health Organization’s prequalification, which allowed for its procurement by Gavi, the Vaccine Alliance and UNICEF for broader use across Africa. Overall, some 2.5 million doses of this vaccine have been secured for African countries. But it’s unclear how this vaccine impacts children under 12 years old, Ngongo said. When WHO prequalified the vaccine, they specified that it can be used “off-label” in children under 18 when “benefits of vaccination outweigh the potential risk.” Kaseya blamed the international community for dropping the ball on researching mpox, which he said is part of the reason there are so many gaps in understanding. In July 2022 , WHO declared a public health emergency of international concern as mpox spread globally — and research focused on the strain known as clade 2b, which was circulating in Europe and the U.S., Kaseya said. But the clade circulating in Africa was sidelined. “They knew that there was a Clade 1 in Africa. They didn't conduct studies. They didn't conduct research for the Clade 1,” Kaseya said. clade 1 is known for more serious infections and a higher mortality rate than clade 2b. The international emergency was declared over in May 2023 after cases declined globally. But the disease continued to circulate in DRC — leading to the discovery of a new strain, clade 1b, last year — and ultimately the declaration of another public health emergency of international concern this August. Now, health workers are attempting to mitigate the emergency but don’t have access to rapid tests — which might have not been the case if research into developing them had been prioritized in recent years, Kaseya said. He said the majority of the unknowns around mpox are due to international partners not wanting “to see the reality” of what was occurring in Africa. “Otherwise, today we would not talk about all of these unknowns,” he said.