Enhancing dengue diagnosis and case management

Laboratory confirmation of dengue virus infection is important. Although in practice diagnosis is often made by clinical signs and symptoms only, dengue in its febrile phase cannot be clinically differentiated from other vector-borne viral and parasitic diseases, such as malaria, chikungunya and Zika fever.

Diagnosis may involve detection of the virus, viral nucleic acid, antigens or antibodies, or a combination of these entities. Laboratory tests using NS1 (non-structural protein 1) antigen can provide early diagnosis in febrile patients. After the onset of illness, the virus can be detected in serum, plasma, circulating blood cells and other tissues for 4-5 days. During the acute stage of the disease, virus isolation, nucleic acid or antigen detection can be used to diagnose the infection. At the end of the acute phase of infection, serology is the method of choice for diagnosis. Serological assays to detect specific immunoglobulin M (IgM) or immunoglobulin G (IgG) antibodies to dengue virus are widely available and can provide an alternative to virus isolation or polymerase chain reaction to support the diagnosis of dengue fever. First-time (primary) dengue virus infections typically have a stronger and more specific IgM response; subsequent (secondary) infections show a weaker IgM response but a strong IgG response. These differing IgM response patterns to infection underscore the need to evaluate the sensitivity and specificity of commercially available tests, especially for diagnosis of secondary dengue virus infections.

Currently, dengue is one of the most important epidemic infectious diseases of humans. Major epidemics in large tropical urban centres are caused by all four serotypes and result in significant morbidity and mortality, especially in resource poor countries where they often strain primary health care and create chaos as hospitals and clinics become overloaded with patients.

Mortality from dengue can be reduced to almost zero by implementing timely, appropriate clinical management that involves early clinical and laboratory diagnosis, oral and intravenous rehydration, staff training and reorganization of health services. A successful clinical outcome requires effective and early management of cases provided by clinical evaluation of hydration and recognition of comorbid conditions, accurate differential diagnosis, supported by rapid laboratory assessment/confirmation and early response to severe disease. Clinical incidence data are instrumental to mobilizing outbreak control. 

The key is early recognition and understanding of the clinical problems during the different phases, especially for the treatment of dehydration and plasma leakage with oral or intravenous rehydration. For mortality from dengue, investigations (including autopsies) and clinical audits are necessary to establish the primary cause of death, the results of which should be fed back to the health care system to achieve delivery of high-quality care. The national clinical dengue management guidelines should be referred to for further details.