Experts still don’t know why so few cases of the new coronavirus have been reported in Africa, despite China – where the virus originated – being the continent’s top trading partner and the continent having a population of 1.3 billion people.

Although the official number of cases in Egypt spiked from two to 59 over the weekend, including 33 people who were on a Nile cruise, across Africa the number of cases has stayed low.

As of Tuesday morning there were just 95 official cases on the continent, though two countries – Togo and Cameroon – reported their first cases over the weekend. The spread in Africa is of concern because of the fragility of some countries’ healthcare systems, and the continent already faces big public health issues, particularly malaria, TB and HIV.

The World Health Organization (WHO) has rushed to beef up the ability of African countries to test for the virus and train health professionals in caring for people affected by it. Only Senegal and South Africa had labs that could test for the virus at the end of January, but 37 countries now have testing capability.

Mary Stephen of the WHO, who is based in Brazzaville in the Republic of the Congo, says she believes the running tally of cases is accurate because more than 400 people have been tested for covid-19 across Africa so far. “I wouldn’t say it’s an underestimate,” she says.

“It will always be possible to miss cases and that’s always been admitted in the UK,” says Mark Woolhouse at the University of Edinburgh, UK. But given heightened awareness in Africa, the lack of coronavirus-linked deaths on the continent implies there aren’t yet big undetected outbreaks, he says. “If there were major outbreaks, of the scale that Italy or Iran have had, anywhere in Africa, I would expect those deaths to be well above the radar by now.”

On the question of whether the low cases are due to a lack of detection or the virus simply not having yet spread to many African countries, David Heymann at the London School of Hygiene and Tropical Medicine (LSHTM) says simply: “Nobody can answer that.”

Jimmy Whitworth at LSHTM says he doesn’t think we can say why the numbers are so low but one possible reason could be isolation measures implemented by countries. Most cases in Africa have been imported not from China but from Europe. Four African countries have imposed quarantines on visitors from coronavirus hotspots. Unlike virus cases, quarantine numbers aren’t being reported.

More broadly, on the monitoring efforts to detect the virus at airports and other entry routes, Whitworth says “a lot’s being done”, citing coordination by the WHO and both the African and US Centres for Disease Control. Rwanda, for example, has recruited final year medical students to undertake screening at airports, says Woolhouse.

Vittoria Colizza at Sorbonne University in France, author of a paper about African countries’ vulnerability to covid-19, says a combination of factors could account for the low case numbers.

One reason could simply be the nature of the virus: a lot of people may be travelling around infected but without symptoms, says Colizza. She suggests under-detection of incoming cases and a lack of capacity to monitor and do active surveillance could also be involved.

Colizza’s analysis of the first 300 cases exported from China suggests that about 60 per cent of people who were infected were missed by detection. Other research led by Ashleigh Tuite at the University of Toronto, Canada, has suggested under-reporting by 27 to 75 per cent in Italy, taking into account both imported cases and transmission within the community.

The WHO says “most” of the 37 countries in Africa with testing capacity have between 100 and 200 testing kits. Researchers think many more will probably be needed as cases spread, but that this is a start. “It is much better to have some than no capacity at all,” says Woolhouse.

African countries are both vulnerable and potentially more resilient to the coronavirus. On the one hand, the population is much younger than in Europe and China. The median population age in the UK is 40.2 and in China it is 37, but this figure is 17.9 in Nigeria, Africa’s most populous country. “If you look at the statistics from China, the people that have worse prognosis are the older people, not necessarily the young,” says Stephen.

The flipside is healthcare systems are generally more fragile in many African countries, says Stephen. “If this outbreak comes in, it’s going to collapse the healthcare systems,” says Heymann.

The big risk is that fighting a coronavirus outbreak becomes a distraction for healthcare systems tackling other diseases that burden the region, including malaria and measles, says Woolhouse. He points to the 2014-16 Ebola outbreak, where many of the thousands of resulting deaths were due to resources being diverted away from other diseases.