Rapid diagnostic tests vital to expanding use in remote settings
When somebody has a fever in sub-Saharan Africa, the default diagnosis is almost always malaria. It turns out that in many cases, that diagnosis could be wrong. Malaria and diagnostics experts now say that it is time to break away from these old practices.
For decades many malaria endemic countries, particularly in sub-Saharan Africa, have relied upon simply a clinical diagnosis of malaria, largely due to the inaccessibility of reliable and affordable diagnostic tools. In practice this means that a fever is usually assumed to be malaria, and patients are often given anti-malaria medication. Unfortunately, it appears that this is often the wrong treatment for the wrong disease. This is especially true in difficult to reach rural areas.
The development of accurate malaria rapid diagnostic tests (RDTs) that have been adapted for use in remote settings presents an exciting opportunity to improve patient care and better understand the true burden of malaria and non-malaria causes of fever. WHO now strongly recommends confirmation of a malaria diagnosis prior to treatment with artemisinin combination therapies (ACTs), which is largely considered the best current treatment for the disease. While there are initiatives to make ACTs more affordable, access to accurate and inexpensive diagnostics remains a problem. RDTs may solve that.
In countries like Senegal, where RDTs have been introduced on a national scale, only a third of the suspected malaria fever cases are confirmed by the new diagnostic tests. In one district in Zambia, in a study cosponsored by TDR, the quarterly number of suspected malaria cases dropped from 10,000 to 10 after the introduction of RDTs. These drops in reported malaria cases were matched with corresponding drops in ACT use.
These examples beg the question, if malaria isn't causing febrile illnesses, what is? Causes of non-malarial fever vary regionally and seasonally, and researchers admit that there are huge gaps in their knowledge about the true burden of many diseases. In children, malaria, pneumonia, septicaemia (commonly known as blood poisoning) and meningitis are clinically indistinguishable and even co-infection is not uncommon. Much more research is needed to guide case management of non-malarial fever and to develop diagnostics than can accurately detect other serious illnesses, said Dr. Cunningham, a technical officer who specializes in diagnostics at TDR.
In collaboration with ministries of health in 4 African countries, some of these pressing questions are being addressed by TDR:
- Are children who have a negative RDT result, or are severe, being referred for diagnosis and management?
- Are referred patients following referral advice?
- Where do patients who are referred go for treatment, and what is done?
- What is the diagnosis and what is the outcome?
- What happens to children who have a positive test result but who do not respond to antimalarials?
The answers to these questions and other research quantifying the burden and overlap of childhood infections are important to guide integrated case management of childhood infections in the era when diagnosis of malaria becomes increasingly used for malaria. Development of diagnostics that can accurately detect other serious illnesses (ideally simultaneously) will further help.
The World Health Organization (WHO) has issued recommendations on the procurement of RDTs, based on independent comparative performance data published by WHO, TDR and the Foundation for Innovative New Diagnostics (FIND). It is still too early to tell what impact they are having in the field. However, it does appear that many of the big aid agencies are using the WHO guidance to inform their RDT choices and to offer appropriate treatment for non-malaria fevers, said Dr. Cunningham.
For more information contact Dr Jane Cunningham, cunninghamc@who.int
