Enhanced passive screening and diagnosis for gambiense human African trypanosomiasis in north-western Uganda – Moving towards elimination

Abstract

IntroductionThe incidence of gambiense human African trypanosomiasis (gHAT) in Uganda has been declining, from 198 cases in 2008, to only 20 in 2012. Interruption of transmission of the disease by early diagnosis and treatment is core to the control and eventual elimination of gHAT. Until recently, the format of available screening tests had restricted screening and diagnosis to central health facilities (passive screening). We describe a novel strategy that is contributing to elimination of gHAT in Uganda through expansion of passive screening to the entire population at risk.Methodology / Principal findingsIn this strategy, patients who are clinically suspected of having gHAT at primary health facilities are screened using a rapid diagnostic test (RDT), followed by parasitological confirmation at strategically located microscopy centres. For patients who are positive with the RDT and negative by microscopy, blood samples undergo further testing using loop-mediated isothermal amplification (LAMP), a molecular test that detects parasite DNA. LAMP positive patients are considered strong suspects, and are re-evaluated by microscopy. Location and upgrading of facilities to perform microscopy and LAMP was informed by results of georeferencing and characterization of all public healthcare facilities in the 7 gHAT endemic districts in Uganda. Three facilities were upgraded to perform RDTs, microscopy and LAMP, 9 to perform RDTs and microscopy, and 200 to screen patients with RDTs. This reduced the distance that a sick person must travel to be screened for gHAT to a median distance of 2.5km compared to 23km previously. In this strategy, 9 gHAT cases were diagnosed in 2014, and 4 in 2015.ConclusionsThis enhanced passive screening strategy for gHAT has enabled full coverage of the population at risk, and is being replicated in other gHAT endemic countries. The improvement in case detection is making elimination of the disease in Uganda an imminent possibility.

Optimising passive surveillance of a neglected tropical disease in the era of elimination: A modelling study

“…In 2013, a new passive surveillance strategy was implemented which saw the number of facilities participating in passive surveillance increase from four to 212 and subsequently adjusted to 170. The majority of facilities conduct only serological surveillance using a rapid diagnostic test (RDT) and 12 accept referrals of RDT positive patients for confirmation by microscopy (24).…”

“…Plans to scale back the number of passive surveillance sites operating RDTs are ongoing in Uganda, with the target of ensuring that by 2030, >50% of at-risk populations should live within 1-hour of a health facility with HAT diagnostics and >95% should live within 5-hours (25). The number of health facilities using HAT RDTs were reviewed in July 2014 and September 2015, in response to the evolving epidemiological situation of g-HAT in Uganda (24). Previous analyses utilised the Euclidean distance to facilities as opposed to estimates of travel time.…”

“…During 2017, there were 170 HAT diagnostic centres in operation within north-western Uganda (24). Each facility utilises either RDTs alone (39), or RDTs and microscopy techniques (40), and supplemented by mini-anion exchange centrifugation technique (mAECT) (41), with three of these second group facilities also equipped with loop-mediated isothermal amplification (LAMP) for identifying suspected g-HAT cases ( Fig.…”

Point-of-care and point-of-‘can’: leveraging reference-laboratory capacity for integrated diagnosis of fever syndromes in the tropics

“…In addition to integrating data from sentinel sites, the ability to receive transmitted patient results from remote laboratories is being exploited by some human African trypanosomiasis control programmes [47]. Beyond reduced turn-around time, post-analytic data transfer to the field opens the possibility of placing powerful information in the hands of care-givers at the point of care, such as real-time cumulative AST results according to region or health centre, or modular treatment guidelines informed by local epidemiology and accounting for tests available at the point of care in a given area.…”

Understanding the Role of the Diagnostic ‘Reflex’ in the Elimination of Human African Trypanosomiasis

“…As cases of HAT recede in many areas of Africa today, this more costly active approach to case detection and treatment has given way to 'passive' case detection approaches which test only people with suggestive symptoms and rely on cases being detected during peoples' routine interactions with HCWs in health facilities. The recent development of rapid diagnostic tests (RDTs) for HAT, moreover, has enabled passive detection strategies to be reformed [10]. As with other RDTs, their ease of use means the first screening test in a step-wise algorithm can be taken out of hospital laboratories into primary care settings, broadening the pool of diagnosers able to test patients when they suspect disease.…”