Closing in on the reservoir: pro-active case detection as a strategy to contribute to Plasmodium falciparum elimination in an area of multidrug resistance in Cambodia MSF in Chey Saen District Preah Vihear Province – Cambodia Gabriele Rossi Research Coordinator MSF OCB Cambodia London Scientific Days, May 19 2017, London New strategy within the effort/endoavour of contributing to eliminate Pf in an area of artemisinine resistance in Camboida. Cambodia is one of the 5 countires of the GMS where AR was discovered in 2008. Today in GMS ACTs are failing to various degree, driven by AR, and in Cambodia the situation is dramatic as 4 out of the 5 ACT available present TF rate higher than 10%. AR is a publi health a threat as AR might spread to Africa.

Introduction: Area of Intervention Population 22.499 27 villages 28 Village Malaria Workers Malaria drug resistance, fuelled by artemisinin resistance, is a reality in the Greater Mekong Subregion. This situation is challenging one because these countries are experiencing high treatment failure rate of the ACTs, the current cornerstone for treatment of Pf. The Explanation of the background and the imperative need to eliminate Pf in order to avoid spreading of resistance to other parts of the world (Africa) Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Methods: Strategy Season 15-17 Passive case detection (PCD): Early diagnosis and treatment of symptomatic cases. Use of RDT & PCR, by VMW and HC. Follow up 28 days later after treatment, in PCR, for ruling out treatment failure. Surveillance of molecular marker of resistance (K13 and pfmdr1) Reactive case detection (RACD): recruit positives « around » index case: RDT/PCR screening of family and « co-exposed » Pilot of Pro-active case detection (Pro-ACD) : target asymptomatic parasite reservoir, within at risk populations Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Results DHA-PPQ ASMQ In PCR Treatment Failure # Pf Day 0 tested Oct 2015-Jan 2016   # Pf Day 0 tested Result D28 after DHA-PPQ Total positive % positivity Oct 2015-Jan 2016 130 39 30% D28 after introduction of ASMQ as 1st line treatment (from February 2016 ongoing) # followed up in Day 28 Total positive % positivity 50 0% ASMQ Treatment Failure Feb 2016-Mar 2017 Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Results: Markers of Artemisinin and Mefloquine Resistance Out of 194 Pf samples K13 mutations associated with Artemisinin resistance present in 80% of the analyzable samples. pfmdr1 amplification more than 1.5 copies (associated with mefloquine resistance) DHA-PPQ group (Oct 2015-Jan 2016): present in 9% ASMQ group (Feb 2016-Mar 2017): present in 49% of the analyzable P falciparum Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Conclusions : Molecular Markers and Drug Resistance Surveillance K13 mutation is spread and fixed at high level in the district (80% of the Pf are carrying the mutation) ASMQ is proving to be highly efficacious across 1 year span of ‘drug-resistance surveillance’, based on Day 28 PCR monitoring results Drug resistance surveillance needs to stay vigilant, in view of the significant increase of the pfmdr1 in the ASMQ treatment group and the possible resurgence of mefloquine resistance Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Introduction: PILOT of Pro-Active Case Detection (Pro-ACD) Rationale: identifying asymptomatic cases who contribute to form the infectious parasite reservoir In the present study setting, Voluntary Screening and Treatment (VSAT) is defined as a screening and treatment activity focused on high-risk groups: spending night in forest and/or plantation and/or ricefield and/or with past history of malaria Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Methods: Pilot in 3 villages in the period Dec 2015- Mar 2016 Additional cases detected (compared to PCD) Profile of people at risk Feasibility Quantitative study Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection Methods: Outline Check for Positivity Pf with PCR Step 4: Day 28 after treatment Step 1: from Day -14 to Day 0 HP Sensitization: - Asymptomatic malaria - Service promotion for specific groups Treatment in DOT DHA-PPQ Reactive Case Detection Step 2: Day 0 Testing day (RDT + PCR by finger prick) and Malariometric Questionnaire Step 3: by Day 14 See next slide for explanation of HP activities Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Results: Pf cases detected – Comparison PCD/Pro-ACD Pf Detection Rate 1.1% (33 Pf cases out of 3075 tested) PCD 17 Pf case Pro-ACD 33 Pf case Ratio PCD/Pro-ACD = 1:2 Pf cases treated within 13 days Is consistent with the recently published data on numerical parasite DENSITY distribution and is well represented by the image here shown (Iceberg) where the tip is made of patent infections identified by RDT/microscopy and the submersed part by the subpatnt infections. The magnitude/size of the quota intercepted by the low volume PCR is congruent with the ratio 1:2 we obtained, therefore being in favor to the hypothesis that our strategy, by using low volume PCR, identified most of the detectable infections Which is the magnitude of the intercepted asymptomatic/submicroscopic quota of the infectious reservoir? We do not know. The proportion of Pro-ACD/PCD Pf cases (2:1) is consistent with the predicted Geometrical distribution of Pf densities. But the question remains: were we able to detected all what was detectable ? (in terms of population coverage and diagnostic power of the test) The numerical distribution of Pf densities (log normal distribution) tells us that up to 75% of sub-microscopic cases can be detected by high volume PCR (22 parasites/ml). The small volume PCR (on 5 microlt blood) can detect up to 1.000 parasite/ml. Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Results: Coverage & Detection Rate by Age Category Pf Detection rate higher in the age categories most mobilized Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Results: Risk Profiling no association with risk of Pf for spending night time in ricefield (P = 0.6) no association with risk of Pf infection for previous history of malaria (P = 0.5) association with spending night time in forest (P =0.002; OR 3.4 [1.6-7.2]) association with spending night time in plantation (P=0.03; OR 2.3 [1.1-4.9]). Plantations are often embedded in forested areas Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection Conclusions: Pro-ACD Pro-ACD appeared to confirm the forest goers and Plantation goers, spending night time there, as the group holding a significant risk for Pf infection, regardless of gender Pro-ACD, under the form of Screening and Treatment is feasible Pro-ACD found more Pf infections than the PCD, during the same time/place of intervention Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection

Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection Acknowledgments Cambodia National Malaria Center Pasteur Institute - Cambodia Médecins Sans Frontières MSF Project, Preah Vihear Medical Department MSF OCB, Brussels MSF Coordination, Phnom Penh Gabriele Rossi, MSF OCB Cambodia: Pro-Active Case Detection