Rapid Diagnostic Tests and Clinical/Laboratory Predictors of Tropical Diseases in Neurological Disorders in DRC

The impact of neurological disorders is enormous in terms of mortality, morbidity, physical disability and psychological distress, and it is increased in low-resource settings by lack of diagnosis and of treatment facilities as well as delayed management. The frequency of neurological disorders and the pattern of causative conditions are little documented in low-resource primary care settings.In sub-Saharan Africa, the few observational studies conducted for the past 20 years, show that neurological disorders accounted for 7 to 24% of all admissions. Central nervous system (CNS) infections were suspected in one third of all patients admitted with neurological symptoms, with a specific microbial aetiology identified in half of these. Where it has been investigated, up to one third of neurological admissions was related to HIV infection in some settings. Neuro-infections were also the leading aetiologies of common neurological symptoms (such as headache) in African HIV-positive patients, and autopsy studies have demonstrated that CNS infections accounted for 20% of the causes of death in HIV-positive individuals in sub-Saharan Africa.

Most CNS infections may be considered as "severe and treatable diseases", e.g. human African trypanosomiasis (HAT), cerebral malaria, bacterial meningitis, CNS tuberculosis, neurosyphilis, cryptococcal meningitis or toxoplasma encephalitis etc. If left untreated, death or serious sequels usually occur; mortality rates of neurological admissions were as high as 30% in the above mentioned studies. However, outcome may be favourable with timely and appropriate management.

In resource-constrained settings more than elsewhere, such "severe and treatable" conditions should be targeted in priority in the clinical decision-making process. Unfortunately, most neuro-infections present with non-specific symptoms in their early stages, leading to important diagnostic delays. Moreover, neurological diagnoses frequently require advanced technology, but this is far beyond reach of most tropical rural settings, where you have to rely on clinical judgment and first-line laboratory results. However, the confirming or excluding powers of most clinical and laboratory features are limited or have never been adequately quantified, in particular in settings lacking reference diagnostic methods. Several rapid diagnostic tests (RDTs) have been developed in the last decade for conditions like malaria or HIV infection, but their diagnostic contribution has never been evaluated within a multi-disease approach. Most CNS infections with worldwide distribution affect disproportionally the (sub)-tropical regions, while others are restricted to the tropics. Also, many infections with potential neuropathogenicity belong to the group of 17 Neglected Tropical Diseases (NTDs) on which attention has been recently brought. As said above, most of them may be considered as "severe and treatable"; however, in most tropical settings, epidemiology of NTDs and other infectious diseases (IDs) is largely unknown, seriously impairing the case finding and clinical decision-making.

The aim of this research therefore is to improve the early diagnosis of severe and treatable neglected and non-neglected infectious diseases which may present with neurological symptoms in the province of Bandundu, Democratic Republic of Congo (DRC). This will be achieved through the elaboration and validation of new diagnostic guidelines based on epidemiological evidence, combining classic clinical predictors with a panel of simple point-of-care rapid diagnostic tests, and designed with a "panoramic" (not-to-miss) approach.

In particular, the investigators hope to determine the pre-test probability of HAT and other priority neglected tropical diseases/infectious diseases in patients presenting with neurological disorders; to assess the predictive weight of clinical and first-line laboratory features in the diagnosis of HAT and other priority NTDs/IDs; to assess the sensitivity, specificity and predictive values of novel point-of-care RDTs for the diagnosis of HAT and other priority NTDs/IDs in patients with neurological disorders; and to assess the diagnostic performances of combinations of novel and existing RDTs for diagnosing HAT and other priority NTDs/IDs in patients with neurological disorders. Enrolled patients will be managed according the current standard of care in Bandundu, DRC and with the treatments locally available through health facilities/programs.

The objectives and methodology of this second step of our research (evaluation of existing algorithms and elaboration/validation of new guidelines) will be described in a subsequent protocol. Another similar study (described in another protocol) will be conducted in parallel to explore the aetiologies of prolonged fever in the same setting.