Limitations of malaria reactive case detection in an area of low and unstable transmission on the Myanmar–Thailand border

ObjectiveIntegrated community case management (iCCM) of childhood illness is a powerful intervention to reduce mortality. Yet, only 29% and 59% of children with fever in sub-Saharan Africa had access to malaria testing and treatment between 2015 and 2017. We report how iCCM+ based on incorporating active case detection of malaria into iCCM could help improve testing and treatment.DesignA community-led observational quality improvement study.SettingThe rural community of Bare-Bakem in Cameroon.ParticipantsChildren and adults with fever between April and June 2018.InterventionA modified iCCM programme (iCCM+) comprising a proactive screening of febrile children <5 years old for malaria using rapid diagnostic testing to identify index cases and a reactive screening triggered by these index cases to detect secondary cases in the community.Primary and secondary outcome measuresThe proportion of additional malaria cases detected by iCCM+ over iCCM.ResultsWe screened 501 febrile patients of whomPlasmodiuminfection was confirmed in 425 (84.8%) cases. Of these cases, 102 (24.0%) were index cases identified in the community during routine iCCM activity and 36 (8.5%) cases detected passively in health facilities; 38 (8.9%) were index cases identified proactively in schools and 249 (58.6%) were additional cases detected by reactive case detection—computing to a total of 287 (67.5%) additional cases found by iCCM+ over iCCM. The likelihood of finding additional cases increased with increasing family size (adjusted odd ratio (aOR)=1.2, 95% CI: 1.1 to 1.3) and with increasing age (aOR=1.7, 95% CI: 1.5 to 1.9).ConclusionMost symptomatic cases of malaria remain undetected in the community despite the introduction of CCM of malaria. iCCM+ can be adopted to diagnose and treat more of these undiagnosed cases especially when targeted to schools, older children and larger households.

Download Full-text

Effectiveness of reactive case detection for malaria elimination in three archetypical transmission settings: a modelling study

Malaria Journal ◽

10.1186/s12936-017-1903-z ◽

2017 ◽

Vol 16 (1) ◽

Cited By ~ 25

Author(s):

Jaline Gerardin ◽

Caitlin A. Bever ◽

Daniel Bridenbecker ◽

Busiku Hamainza ◽

Kafula Silumbe ◽

...

Keyword(s):

Malaria Elimination ◽

Case Detection ◽

Reactive Case Detection ◽

Modelling Study

Download Full-text

A framework for evaluating the costs of malaria elimination interventions: an application to reactive case detection in Southern Province of Zambia, 2014

Malaria Journal ◽

10.1186/s12936-016-1457-5 ◽

2016 ◽

Vol 15 (1) ◽

Cited By ~ 6

Author(s):

Bruce A. Larson ◽

Thandiwe Ngoma ◽

Kafula Silumbe ◽

Marie-Reine I. Rutagwera ◽

Busiku Hamainza ◽

...

Keyword(s):

Malaria Elimination ◽

Case Detection ◽

Reactive Case Detection ◽

Southern Province

Download Full-text

Improving the efficiency of reactive case detection for malaria elimination in southern Zambia: A cross-sectional study

10.21203/rs.2.21595/v1 ◽

2020 ◽

Author(s):

Fiona R.P. Bhondoekhan ◽

Kelly M. Searle ◽

Harry Hamapumba ◽

Mukuma Lubinda ◽

Japhet Matoba ◽

...

Keyword(s):

Risk Factors ◽

Environmental Risk ◽

Catchment Area ◽

Health Workers ◽

Index Case ◽

Satellite Image ◽

Environmental Risk Factors ◽

Local Health ◽

Case Detection ◽

Reactive Case Detection

Abstract Background: Reactive case detection (RCD) seeks to enhance malaria surveillance and control by identifying and treating parasitemic individuals residing near index cases. In Zambia, this strategy starts with passive detection of symptomatic incident malaria cases at local health facilities or by community health workers, with subsequent home visits to screen-and-treat residents in the index case and neighboring (secondary) households within a 140-meter radius using rapid diagnostic tests (RDTs). However, a small circular radius may not be the most efficient strategy to identify parasitemic individuals in low-endemic areas with hotspots of malaria transmission. To evaluate if RCD efficiency could be improved by increasing the probability of identifying parasitemic residents while screening fewer houses, we incorporated environmental risk factors and a larger screening radius (250 meters) in a region of low malaria endemicity. Methods: Between January 12, 2015 and July 26, 2017, 4,170 individuals (residing in 158 index and 531 secondary households) were enrolled and completed a baseline questionnaire in the catchment area of Macha Hospital in Choma District, Southern Province, Zambia. Plasmodium falciparum prevalence was measured using PfHRP2 RDTs and qPCR. A Quickbird™ high-resolution satellite image of the catchment area was used to create environmental risk factors in ArcGIS, and generalized estimating equations were used to evaluate associations between risk factors and secondary households with parasitemic individuals. Results: The overall parasite prevalence in secondary (non-index case) households was 0.7% by RDT and 1.8% by qPCR. 8.5% (45) of secondary households had at least one resident with parasitemia by qPCR or RDT. The risk of a secondary household having a parasitemic resident was significantly increased in proximity to higher order streams and marginally with increasing distance from index households. The adjusted OR for proximity to third- and fifth-order streams were 2.97(95% CI: 1.04 – 8.42) and 2.30 (95% CI: 1.04 – 5.09), respectively, and that for distance to index households for each 50 meters was 1.24 (95% CI: 0.98– 1.58). Conclusion: Applying proximity to streams as a screening tool, 16% (3) more malaria-positive secondary households were identified than using a 140 m circular screening radius. This analysis highlights the potential use of environmental risk factors as a screening strategy to increase RCD efficiency.

Download Full-text

Reactive Case Detection of Asymptomatic Malaria in Households and Neighbors of Laboratory Confirmed Cases in Raya Kobo District, Northeast Ethiopia

10.21203/rs.2.19723/v1 ◽

2019 ◽

Author(s):

Yimer Melese ◽

megbaru alemu abate ◽

Mulat Yimer ◽

Banchamlak Tegegne

Keyword(s):

Diagnostic Tests ◽

Multivariable Analysis ◽

High Morbidity ◽

Asymptomatic Malaria ◽

Case Detection ◽

Reactive Case Detection ◽

Cross Sectional ◽

Asymptomatic Carriage ◽

Northeast Ethiopia ◽

Asymptomatic Infections

Abstract Background Malaria is the leading vector borne parasitic disease causing enormously high morbidity and mortality worldwide. There have been huge efforts so far to control and eliminate malaria in the world. However, high prevalence of asymptomatic carriage poses a threat on malaria control and elimination programs. Since asymptomatic infections present no overt sign and symptoms, they do not get clinical attention. Moreover, asymptomatic cases are a potential source of infection in high and low transmission settings. Despite the presence of some pocket data, the prevalence of asymptomatic carriage has not yet been known nationally and the current study area as well. Therefore, we aimed to assess the prevalence of asymptomatic malaria cases and associated factors in households and neighbors of laboratory confirmed cases in Raya Kobo district, Northeast Ethiopia. Methods: A community based cross-sectional study was conducted from February to April, 2019 among 270 study participants selected by convenient sampling technique at the community where laboratory confirmed cases were found. A structured questionnaire was used to collect data on socio-demographic characteristics, individual and household level factors. The data were entered in Epi Data 3.1 version and analyzed by using SPSS version 20. Variables with P<0.25 in the bivariable analysis were taken to the multivariable analysis to control potential confounders, and p< 0.05 was considered statistically significant. Results: The overall prevalence of asymptomatic malaria was 7.0%, with 3.0%, 5.2% and 12.0%, respectively by Rapid diagnostic tests (RDT), Microscopy and Polymerase chain reaction (PCR). Majority of the infections (73.7%) were identified from index households. PCR detected asymptomatic infections about 2.7 and 2.3 folds higher than RDT and microscope, respectively. Previous malaria history (AOR: 4.030, 95% CI: 1.021-15.903), living with index cases (AOR: 3.880, 95% CI: 1.275-11.806) and family size > 6 members (AOR: 4.820, 95% CI: 1.260-18.437) were significant predictors of Plasmodium spp infection.Conclusion: Reactive case detection had identified considerably higher asymptomatic malaria cases at the community. Therefore, active case investigation should be established in the community by tracking the symptomatic cases at the health facilities. Diagnostic tests involving the PCR should be implemented in the surveillance of asymptomatic malaria. Active malaria cases should also be treated.

Download Full-text

Molecular methods for tracking residual Plasmodium falciparum transmission in a close-to-elimination setting in Zanzibar

10.21203/rs.2.17710/v2 ◽

2020 ◽

Author(s):

Benjamin Grossenbacher ◽

Aurel Holzschuh ◽

Natalie Hofmann ◽

Kali Abdullah Omar ◽

Logan Stuck ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Filter Paper ◽

Geometric Mean ◽

Dried Blood Spots ◽

Infection Prevalence ◽

Case Detection ◽

Molecular Monitoring ◽

Reactive Case Detection ◽

Direct Pcr ◽

Optimal Test

Abstract Background Molecular detection of low-density Plasmodium falciparum infections is essential for surveillance studies conducted to inform malaria control strategies in close-to-elimination settings. Molecular monitoring of residual malaria infections usually requires a large study size, therefore sampling and diagnostic processes need to be economical and optimized for high-throughput. A method comparison was undertaken to identify the most efficient diagnostic procedure for processing large collections of community samples with optimal test sensitivity, simplicity, and minimal costs. Methods In a reactive case detection study conducted on Zanzibar, parasitaemia of 4590 individuals of all ages was investigated by a highly sensitive quantitative (q) PCR that targets multiple var gene copies per parasite genome. To reduce cost, a first round of positivity screening was performed on pools of dried blood spots from five individuals. Ten cycles of a pre-PCR were performed directly on the filter paper punches, followed by qPCR. In a second round, samples of positive pools were individually analysed by pre-PCR and qPCR. Results Prevalence in household members and neighbors of index cases was 1.7% (78/4590) with a geometric mean parasite density of 58 parasites/µl blood. Using qPCR as gold standard, diagnostic sensitivity of rapid diagnostic tests (RDTs) was 37% (29/78). Infections positive by qPCR but negative by RDT had mean densities of 15 parasites/µl blood. Conclusion The approach of pre-screening reactive case detection samples in pools of five was ideal for a low prevalence setting such as in Zanzibar. Performing direct PCR on filter paper punches saves substantial time and justifies the higher cost for a polymerase suitable for amplifying DNA directly from whole blood. Molecular monitoring in community samples provided a more accurate picture of infection prevalence, as it identified a potential reservoir of infection that was largely missed by RDT. The developed qPCR-based methodology for screening large sample sets represents primarily a research tool that should inform the design of malaria elimination strategies. It may also prove beneficial for diagnostic tasks in surveillance-response activities.

Download Full-text