PCR can identify the influenza A (H1N1) virus
Many developing countries have "extremely limited capacity" to diagnose diseases such as swine flu and are likely to remain this way for decades, according to a public health expert specialising in pandemic preparedness.
There has been substantial investment in developing countries to support animal and human health surveillance, says Richard Coker, professor of public health at the UK-based London School of Hygiene and Tropical Medicine (LSHTM). But they still lack resources and face logistical issues.
"Thus new emerging infectious diseases may be extremely challenging to identify," he told SciDev.Net. "And existing diseases that pose a pandemic threat may not be identified in a timely manner to support containment efforts."
He predicts that it could be "decades, if ever" before every country has diagnostic capacity, especially as donors reduce funding in light of the global financial crisis.
His comments come as the WHO rushes kit to diagnose swine flu — officially known as influenza A (H1N1) — around the world.
The WHO has both National Influenza Centres (NICs) reference laboratories in over 60 countries. Those equipped to carry out a procedure called reverse transcriptase polymerase chain reaction (RT-PCR) will receive the reagents they need to detect swine flu in the next few days, Nikki Shindo, a medical officer in the WHO's Epidemic and Pandemic Alert and Response Department, told SciDev.Net.
These reagents, or 'primers', are short stretches of genetic material that help identify the virus. Without them, laboratories cannot detect the virus, says Shindo. But with them, RT-PCR should confirm the virus' presence in about two hours.
The NICs monitor seasonal influenza circulation for the WHO through the Global Influenza Surveillance Network. Not all have the capacity to do RT-PCR, but those that do not have been linked to those who do so they can send their samples to them, says Shindo.
Similarly, entire countries that lack RT-PCR capacity will send their samples to other countries for analysis using the WHO courier system.
Enrique Paris, a member of Chile's medical expert advisory committee dealing with the swine flu situation, says that the lack of diagnostic capacity in developing countries is hindering the detection of cases.
In Mexico itself, a lack of RT-PCR equipment could be behind the confusion over the number of cases and deaths caused by the virus. Authorities had been reporting around 150 deaths but only 29 have been confirmed so far to be from swine flu.
The country received 15 machines to carry out RT-PCR only last week (30 April). Until then scientists had been relying on more basic tests that distinguish between influenza subtypes but do not definitively diagnose the specific virus, according to Celia Alpuche, adjunct director general of the Institute of Epidemiological Diagnosis and Reference.
Shindo agrees that there are legitimate concerns about delayed diagnosis and says that the WHO is constantly communicating through the Global Influenza Surveillance Network to prepare for the potential spread of the H1N1 virus.
Diagnostic capacity in developing countries has nevertheless increased in recent years, particularly after the 2003 SARS outbreak and emergence of H5N1 bird flu.
Some developing countries — particularly in Asia — have developed some influenza laboratory capacity either independently or with the support of organisations such as the US Centers for Disease Control or the France-based Pasteur Institute, Sandra Mounier-Jack, lecturer in health policy and expert in pandemic preparedness at the London School of Hygiene and Tropical Medicine told SciDev.Net.
And the WHO has a long-term strategy to strengthen surveillance and diagnostic capacity in developing countries as part of the International Health Regulations, which were formulated in 2005 and require that countries strengthen capacity to report newly emerging infections. The WHO strategy will be "strengthened" in light of the current emergency, says Shindo.
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