CASE DETECTIONby Dr Mikhail Ejov

WHO Training in Malaria Elimination in the Greater Mekong Sub-Region, 10-21 August 2015, Chiang Mai Thailand 1

Main differences between malaria control and elimination programmes

WHO Training in Malaria Elimination in the Greater Mekong Sub-Region, 10-21 August 2015, Chiang Mai Thailand 2

The fundamental difference between malaria elimination and control is that: A malaria control programme is concerned with malaria as a disease and reducing the burden of disease is a primary goal, whereas

A malaria elimination is concerned with malaria as a parasitic infection and reducing locally acquired cases and active foci of malaria to zero is a main goal.

This difference is of a paramount significance, and differences on case management between these two types of the programmes are derived from this one.

Item Burden-reduction phase

Malaria elimination phase

Case definition All persons with clinical symptoms are considered as a malaria case

All persons with parasitaemia (including those with gametocytes only) are considered as a malaria case, regardless of the presence or absence of clinical symptoms (symptomatic or asymptomatic)

Purpose of case management

Early diagnosis and effective treatment of all symptomatic cases to reduce morbidity and mortality as well as transmission

Early detection and adequate management of all infections including asymptomatic, to prevent onward transmission

CASE DETECTION PASSIVE CASE DETECTION (PCD) is the

detection of malaria cases among people who go at their own initiative to a public or private sector health facility or community health workers to get treatment, usually for a febrile disease

ACTIVIE CASE DETECTION (ACD) is the screening for malaria infections at community and household levels by malaria/general health staff or voluntary health workers or mobile malaria clinics/teams on regular or planned or ad hoc basis

In addition to PCD, ACD is recommended

for investigating malaria foci and screening malaria infections in high-risk population groups (migrant workers, mobile and tribal populations) that are often underserved by existing health services

ACD can be conducted as fever screening followed by parasitological examination of all febrile patients, or as parasitological examination of a target population without prior fever screening

CASE DETECTION

In the phase of malaria elimination:Active screening for malaria cases should be actively advocated

in all active fociACD should be enhanced in residual foci of malaria that show

signs of refractoriness. The norms may be less rigid in foci that have demonstrated a good response to the applied measures

Along with PCD every attempt should be taken to actively screen migrant and mobile populations and ethnic groups in remote and border areas. It is well known that malaria tends to take refuge in such places and populations, as they often neglected and not adequately covered by the health services

A good rapport has to be established with the military and police medical services, and the same applies to jails and other institutions

CASE DETECTION

WHO Training in Malaria Elimination in the Greater Mekong Sub-Region, 10-21 August 2015, Chiang Mai Thailand 7

IN THE ELIMINATION PHASE WHEN THE NUMBER OF LOCALLY ACQUIRED CASES AND SLIDE/RDTs POSITIVITY RATES BECOME LOW ANY ATTEMPT

SHOULD BE TAKEN TO KEEP ANNUAL BLOOD EXAMINATION RATES (ABER) OF 5% OR MORE

WHO Training in Malaria Elimination in the Greater Mekong Sub-Region, 10-21 August 2015, Chiang Mai Thailand

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The detection of malaria infection is based on blood examination by RDTs and microscopy.

With quality assurance, both diagnostic methods are suitable for case management and routine surveillance mostly based on PCD

However, microscopy has advantages for follow-up of patients, detection of gametocytes and determination of parasite density

While quality-assured microscopy and RDTs are the most widely used methods for malaria diagnosis, new more sensitive tools based on PCR and other molecular techniques can be used to detect submicroscopic infections

CASE DETECTION

Diagnostic nuclear acid amplification

(NAA) techniques with a higher sensitivity than RDTs and microscopy, such as polymerase chain reaction (PCR) and other molecular techniques, which are not presently recommended by WHO for routine diagnosis of malaria can be considered for detection of asymptomatic and low-density parasite carriers in specific settings

CASE DETECTION

WHO Training in Malaria Elimination in the Greater Mekong Sub-Region, 10-21 August 2015, Chiang Mai Thailand 10

An NAA-based test with an analytical sensitivity of about 2 parasites/ml can be used to detect asymptomatic and low-density infections in low-transmission settings, and is recommended for malaria epidemiological surveys and even focus investigation

Since RDTs and microscopy are not sufficiently sensitive for mass screening and treatment in low-transmission settings, the field adapted classic/quantitative PCR and LAMP methods should be considered for this purpose

CASE DETECTION

WHO Training in Malaria Elimination in the Greater Mekong Sub-Region, 10-21 August 2015, Chiang Mai Thailand 11

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