LONDON, Nov 15 (Reuters) - Global health advocates have

written to the makers of a key mpox diagnostic test to call for

its price to be cut from around $20 per test to $5, to help

tackle low testing rates in poorer countries badly hit by the

virus.

Medical diagnostics firm Cepheid's GeneXpert mpox test is

one of three approved for emergency use by the World Health

Organization, but the price is prohibitive for countries like

the hardest-hit Democratic Republic of Congo, activists said.

Mpox was declared a global public health emergency by the

WHO this summer, when an outbreak in Congo began to spread to

neighbouring countries. The virus typically causes flu-like

symptoms and pus-filled lesions and can kill.

This week, WHO said cases in Africa showed a "general rising

trend" although they may be levelling off in parts of Congo. But

a lack of tests is hindering the capacity to confirm cases,

particularly in Congo, one of the world's poorest countries.

"We urge you to lower the price of the mpox test cartridges

to $5 and prioritize supply for African countries fighting mpox

outbreaks," read the letter sent by groups including rights NGO

Public Citizen and medical charity Medecins Sans Frontieres.

Cepheid's test is particularly important because machines

that process the results are available across Africa, as they

are also used for tuberculosis testing.

Danaher ( DHR ), the parent company of Cepheid, reduced its

TB test prices to $7.97 last year after pressure from activists.

The companies did not immediately respond to a request for

comment.

The $5 price tag proposed by advocates is based on research

showing that the tests can be produced for less than that.

Public Citizen's access to medicines director Peter

Maybarduk said the recent WHO approval was an opportunity to

ramp up testing. "Lower prices would help health agencies meet

the moment," he said.

(Reporting by Jennifer Rigby

Editing by Ros Russell)