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low action by the US Congress to pay for a response to the Zika virus has public health laboratories robbing from other funds as they scramble to build the testing capacity needed to identify local cases. In Florida, the backlog has anxious pregnant women waiting more than six weeks for results that should take days. And this doesn’t even include the additional challenges labs face to comply with the latest federal recommendations to screen all donated blood.

Clearly, the nation is struggling to meet the demand for Zika testing.

We’re not alone. The problem is even worse in developing countries — including many in which Zika has already wreaked havoc or now threatens to do so. There, clinical testing is offered by the occasional network of unregistered laboratories operating without regulatory oversight. Services might be of too poor quality to be of any worth in medical decision-making.

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In fact, an independent review of the response to the Ebola virus outbreak recommended that the US Department of Health and Human Services “continue to help strengthen the public health and medical care infrastructure and response capabilities of other countries.”

Without the ability to test for and diagnose disease, it is difficult to detect, treat, and control the spread of deadly and debilitating infectious diseases like Ebola and Zika. Physicians must then diagnose disease based on physical symptoms alone — often basing their decisions on a “suspected case” rather than a confirmed case. This has implications beyond a single patient or disease. When physicians must treat patients without confirmatory results, some patients end up receiving unnecessary and potentially harmful treatments.

In countries in Africa where malaria is endemic, for example, more than 80 percent of treatments are started without a confirmed diagnosis, despite the World Health Organization’s recommendations otherwise. Such overuse of antimalaria drugs factors into the emergence of drug-resistant pathogens.

Even when no treatments are available, the inability to test for a disease means that individuals with mild or no symptoms can be missed entirely during an outbreak, allowing the disease to spread silently. The low numbers of Zika cases in Haiti and Indonesia are likely wrong because these countries can’t adequately test for the disease.

The availability of high-quality testing and access to trained pathologists and laboratory medicine professionals can help lay the groundwork for rapid and effective responses to potential outbreaks. Unfortunately, labs and the trained professionals needed to operate them are in short supply in many countries.

For example, all sub-Saharan countries, except Botswana and South Africa, have less than two pathologists for every 1 million people. Haiti, a country of over 1 million people, has just seven pathologists. In contrast, there are 18,000 pathologists in the US — around 56 per million people.

Efforts to improve access to clinical testing and pathologists in the developing world are underway. Heart to Heart International, for example, has been training Haitian laboratory professionals on quality management and improving compliance with standards. Another organization, Pathologists Overseas, provides training, information systems, and external quality control materials to laboratories in Africa and the Caribbean.

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Other solutions are taking place outside of the lab entirely. Low-cost, low-tech, rapid diagnostic tests that are similar to at-home pregnancy tests exist for malaria and HIV. They can be taken to communities in need by local health workers. Expanding the diseases covered by such tests is a sustainable move, since many countries use community health workers to promote a wide variety of care.

Researchers are even developing technologies that bring advanced testing to the point-of-care in low-resource communities. Innovative designs couple communication systems to new diagnostic platforms for use in remote environments. Designated professionals, who may be far from the testing location, provide oversight and aid in epidemiologic reporting and tracking of results. To be sure, there is no single entity that oversees the pathway or incentives for development of such tests. This may have prevented necessary Ebola diagnostics from reaching the field in time.

Developing countries have massive needs that stretch across the medical spectrum. Laboratory services are just one part of a larger requirement for equitable care. That said, access to accurate and timely test results lets patients receive appropriate care and can provide information that informs policy and treatment decisions.

In the US, development of a national laboratory response to the Zika outbreak is essential — though difficult without federal funding. However, until the poorest and most vulnerable parts of the world also build their diagnostic capacity, global health challenges will grow unchecked and continue to threaten public health, both abroad and eventually within our borders.

Shannon Haymond, PhD, is associate professor of pathology at Northwestern University Feinberg School of Medicine. Sarah Brown, PhD, is assistant professor of pediatrics at Washington University in St. Louis School of Medicine.

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