Quality Assurance of Malaria Microscopy

I. Introduction


The effective treatment of malaria largely depends on the accuracy of diagnosis. Microscopy remains as the gold standard in malaria diagnosis. Quality microscopy can be achieved by implementing a quality assurance system (QAS) that ensures and maintains high accuracy, reliability and efficiency of laboratory services nationwide.

Support for early diagnosis and treatment of malaria from various sources has scaled up in previous years. Guided by the Malaria Program, microscopy services in the Rural Health Units (RHUs) and hospitals have been strengthened. Barangay Malaria Microscopy Centers (BMMCs) were also established even in remote malarious areas to provide immediate microscopy services. To ensure high quality microscopy services at various levels of health care, a quality assurance system must be implemented.

II. Objectives


This Chapter aims to guide local health managers and service providers in ensuring reliable microscopy services in their respective localities. Specifically, it aims to:

(1) describe the quality assurance system for malaria microscopy, and

(2) detail the processes and procedures in ensuring accurate and reliable microscopy services.

III. Policy Directions


Quality malaria microscopy is assured through the establishment of a 3-level microscopy quality assessment system.

1. All health facilities providing malaria microscopy services must undergo validation of blood films by qualified provincial/regional validators;

2. All provinces must have a qualified validators certified through regular proficiency assessments every 2 years; and

3. A national core group of trainers/validators certified by an independent body must be sustained by the Malaria Program.

IV. Quality Assurance System for Malaria Microscopy


Microscopy services are provided by existing microscopy centers comprising of the RHUs, hospitals, laboratory facilities and BMMCs. These are manned by microscopists who could either be a medical technologist, a laboratory technician, other health staff or community volunteer worker who underwent special training on malaria diagnosis.

Quality microscopy is provided by competent microscopist adhering to standards and protocols, with available supplies and the necessary equipment.

Assuring quality of microscopy begins at the point of service but needs to be sustained through a 3-level QAS. At first level, microscopists have to undergo the appropriate training courses provided by the National Core Group of Trainers (NCGT). In order to maintain quality microscopy services, the proficiency skills of performing microscopists must be validated by certified provincial/regional malaria microscopy validators on a regular basis (Level 2). In turn, the proficiency skills of validators must be subject to the proficiency assessment conducted by Research Institute for Tropical Medicine-National Reference Laboratory (RITM-NRL) every 2 years while the training competencies of NCGT members must be regularly assessed by an external expert through its Regional Accreditation and External Quality Assurance (EQA) Program (Level 3). The following describes the 3-level QAS of malaria microscopy.

Figure 6.1 Quality Control and Quality Assessment of Malaria Microscopy*

V. Implementing Guidelines


Level I. Training of Microscopists for Malaria Diagnosis

As a first level of quality assurance for microscopy, microscopists must first undergo the Basic Malaria Microscopy Training, and a regular refresher course every 3 years provided by the NCGT. Health facilities without a qualified malaria microscopist must be guided with the following:

1. The head of the health facility must identify and designate a staff member to perform malaria microscopy. The designated staff must undergo the basic microscopy training and must satisfy the following criteria:

If the designated staff is a:

• Medical Technologist or Non-Medical Technologist deployed in RHUs/hospitals and laboratory

(i) with good visual acuity

(ii) not more than 45 years old

(iii) in good physical and mental condition

(iv) willing to complete the course

(v) committed to serve at least 1-2 years

• Non-medical technologist: Midwife (MW)/barangay health worker (BHW) to be deployed at BMMC.

Same as above and must be able to read, write and perform numeric computations at basic level 

2. The head of the health facility must coordinate with the Provincial Health Office (PHO)/Center for Health Development (CHD) for appropriate training and schedule and make the necessary administrative and financial arrangements in support to the staff to be trained.

3. Microscopist for training will undergo training course recommended according to the category of their profession:

3.1 For medical technologists : 2-week Basic Malaria Microscopy Course

3.2 For non-medical technologists: 5 week Basic Malaria Microscopy Course

4. Trainees who obtain the passing mark of at least 80% in the training can be designated as malaria microscopist.

     4.1 Those with grades <80%:

a. Medical Technologist: to be mentored by the validator for 6 months and take

the same 2-week course. If staff fails, the head of facility needs to mobilize the services of other qualified microscopists in other facilities

b. Non-Medical Technologist: advise head of health facility to recommend another staff to be trained to perform microscopy

     4.2 Those with grades > 80%:

a. Their competencies must be assessed every 3-5 years

b. They must undergo a refresher course with a minimum of 5-day duration that gives emphasis on species identification (for all microscopists) and quantification (for microscopists assigned in RHUs/hospitals/laboratories only).

If microscopist fails the refresher course, the following measures must be undertaken by the validator:

(i)  review and identify areas of weaknesses/gaps in the microscopist performance

(ii) closely mentor and supervise the microscopist

(iii)send panel of slides for practice by the microscopist

Level 2. Quality Assessment of Microscopy Services in Health Facilities

After the initial training on Basic Malaria Microscopy, performance of malaria microscopists needs to be regularly assessed in order to maintain quality microscopy services. This is done through a validation of blood films, on-site supervision, feedback and remedial interventions. The purpose of validation is not to find fault and look for deficiencies but rather to further enhance the skills of the microscopists, and help improve the support system for delivering microscopy services e.g. checking functionality of microscope, adequacy of laboratory reagents/supplies, recording system, etc. Quality assessment should cover the proficiency of microscopists on accuracy, specificity, sensitivity, species identification and parasite quantification.


     1. Blood Film Validation

Quality assessment of microscopy services at the microscopy centers must undergo regular assessment by a qualified validator as reflected in Table 6.1.

Validation is done by randomly selecting a subset of blood films examined at the microscopy centers. These are re-examined by the validator in an independent and blinded manner.

     1.1 Selection of blood films for validation
Based on the total number of reported blood films examined in the previous year, the validator adopts the appropriate selection scheme.

Scheme 1: If there are >240 blood films in a previous year, microscopist must submit 30 blood films examined per quarter regardless of the results to complete a total of 120 blood films reviewed in a year

Scheme 2: If there are 200-240 blood films in a previous year, the microscopist must submit all blood films examined in a quarter for validation regardless of the results

Scheme 3: If there are < 200 blood films in the previous year, the microscopist must submit all blood films examined in the previous 6 months regardless of the results and await the panel of blood films to be sent by the validator every year if validation result of sent blood films is < 20% error or if there are no blood film examined in the previous 6 months

     1.2. Validation Schedule and Frequency
Designated validators must inform the microscopist and head of the microscopy centers of the validation schedule and advise the microscopist to prepare the blood films appropriate for the selected scheme as shown in Table 6.1.


Malaria Microscopy QA: Validation Schemes and Frequency



     1.3 Validation of Blood Films

Scheme 1 and 2

Scheme1 is applicable to microscopist with more than 240 blood films examined in the previous year while scheme 2 applies to microscopists with 200-240 blood films examined in the previous year.

Upon receipt of blood films and the sealed envelope containing accomplished Form 1; the validator must accomplish the following within 2 weeks:

a.  Read the submitted blood films and record the result on Form 2. Malarial Blood Films Report by Validator (Annex 6.2) according to the instructions.


b.  Open the sealed envelope and copy the microscopist’s blood film results written in Columns 11, 13-15 of Form 1 to Columns 10, 11a-c of Form 2. Take note that medical technologist/laboratory technician assigned at the RHU/ hospital/laboratory facility should have accomplished Columns 14-15 of Form 1.


c.  Compare the reading with the blood film readings sent by the microscopist. Indicate in Column 13 of Form 2 the results of the comparison according to the instructions given.

     c.1 Accuracy by species identification, specificity and sensitivity

(i)Accuracy: total number of correctly-read blood films by the microscopist OVER total number of blood films read by the validator MULTIPLIED BY 100

(ii) Sensitivity: total no. of true positive blood films OVER the total number of true positive blood films PLUS false negative blood films MULTIPLIED BY 100

(iii) Specificity: total number of true negative blood films OVER the total

number of true negative blood films PLUS false positive blood films MULTIPLIED BY 100

     c.2 Parasite Quantification: Number of blood films read by microscopist with parasites counts within + 20% deviation from the count of the validator OVER the total number of positive blood films MULTIPLIED BY 100


d.  Assess the quality of thick and thin blood film and the quality of staining. Write
the findings in Columns 14a-c of Form 2 according to the instructions given.

     d.1 Quality of Blood Film. There are 2 blood films prepared for malaria diagnosis,
one thin blood film and one thick blood film per slide.

i. A good blood film is determined by the quality of the thin and thick blood films prepared in a given slide. A good quality blood film requires that both thin and thick blood films are properly prepared as described below.

ii. A good thin blood film is a properly prepared thin film which is thick at the beginning end and thin or feathered on the other end which should not reach the end of the glass slide and should have areas optimal for microscopy having red blood cells that are in a single distinctive layer.

iii. A good thick blood film on the other hand is circular film with 1 cm diameter. The ideal thickness of the blood film should allow for printed text to be readable when it is placed on it.

iv. A poor blood film is when any of the thin or thick blood film did not comply to the above description.

     d.2 Quality of Staining
A good stained blood film is determined by the quality of both the stains of the thin and thick blood films in a given slide.

i. A good stained thin blood film must have:

• a clear background free from debris
• pale grayish pink erythrocyte
• leukocytes with deep purple nuclei and well defined granules
• a deep red chromatin of malaria parasite and clear purplish blue cytoplasm
• for P vivax or P. ovale parasite, stippling shows up as schuffner’s dots and for P falciparum, the larger ring forms show Maurer’s spots in erythrocytes

ii. A good-stained thick blood film must have:

• a clean background free from debris, with a pale mottled-grey color
• deep rich purple leukocytes nuclei
• a deep-red chromatin of malaria parasite and clear purplish blue cytoplasm
• for P. vivax and P. ovale parasites, stippling in the “ghost of host erythrocytes” shows up as schuffner’s dots, especially seen at the edge of the thick film

iii. An under-stained blood film shows a too bluish or purplish film suggesting a high pH.

iv. An over-stained blood film shows a too pinkish film suggesting a low pH.

e. Total the number of inconsistent findings and analyze the results:

     e.1 If the number of blood films with error is 20% and more in any quarter, conduct the on-site visit immediately.
     e.2 If the number of blood films with error is less than 20% in any quarter, ensure to visit the facility at least once a year.


Scheme 3

Scheme 3 is applicable to microscopists with less than 200 slides examined in the previous year. The process of applying Scheme 3 would depend on the presence or absence of blood films examined in the previous 6 months prior to the validation period.

a. For microscopists with blood films examined in the previous 6 months:

     a.1 Use the same set of procedures under Schemes 1 and 2 in validating, analyzing and recording the results.
     a.2 If the results show more than 20% error, schedule at once an on-site visit to the concerned microscopist. In this regard, there is no need to send the panel of 20 slides.
     a.3 However, if the results show less than 20% error, send a panel of 20 slides to the concerned microscopists to further validate his/her microscopy proficiency.

(i). Upon receipt of the returned panel of 20 blood films and sealed envelope containing accomplished Form 1 from the microscopists, perform the same analysis as indicated in Schemes 1 and 2. The analysis though covers only accuracy and specificity of species identification and quantification (if applicable) but not the quality of blood film and quality of staining.

(ii) Based on the validation results, take actions as appropriate and submit the necessary report to the head of the facility within a month after the validation period.

b. For microscopists without any blood film examined in the previous 6 months:

     b.1 Validator should send the panel of 20 blood films to the microscopist concerned.
     b.2 Apply the same validation steps, analysis and appropriate actions as in a.3.


     1.4 Feedback and Reporting

Microscopist and his/her supervisor must be given feedback on the results of the validation as contained in the accomplished Form 2a. Validation Summary Report (Annex 6.3) within one month from the receipt of the blood films for information and appropriate action.

a. Validator provides feedback to the microscopy center specifying the level of accuracy by species, sensitivity and specificity, staining quality and smear size and labeling including recommendations.

b. The accomplished Form 2a must be sent back to the microscopist concerned together with the empty slide box. However, the discrepant blood films should be mounted and saved by the validator for discussion with the microscopist.

c. Report must also include the schedule of the next validation to be undertaken.

d. Copies of the report must be provided to the microscopist, copy furnished the head of the microscopy center, and the heads of PHO and CHD. The report must be endorsed by the head or supervisor of the validator before it is sent out to the proper recipients.

e. Validator must retain hard and electronic copies of the reports.

f. Microscopists must file the validation report for future reference.


2. On-Site Supervision

On-site supervision is an opportunity for both the microscopist and validator to directly interact and discuss the results. It also allows the assessment of the working conditions of the laboratory units and support systems in place (e.g. recording, etc) and helps institute corrective measures, as needed.

     2.1 The timing of the on-site supervision depends on the extent of errors detected.

a. If error is > 20%, the on-site supervision must be done immediately

b. If error is < 20%, on-site supervision must still be done once a year

     2.2 The following are the steps in on-site supervision:

a. Planning. Set schedule for the visit and integrate this schedule with the over-all monitoring plan. Send communication informing the microscopist/s in advance on the date of the visit to ensure his/her presence and prepare records and other materials for the evaluation;

b. Conduct the visit.

     b.1 Pay courtesy call to head of facility:

Hospital - Chief of Hospital

RHU - Municipal Health Officer/Officer-in Charge

BMMC - Barangay Captain / Catchments Midwife

     b.2 Assess the working conditions of the laboratory unit using Form 3. On-site Supervisory Checklist (Annex 6.4)

     i.Interview microscopist on general information.

     ii.Review records and blood films. Randomly select at most 10 blood films from the slide box and validate reading and quality of blood film.

     iii.Inspect microscopy set-up, laboratory supplies/materials, reagents, equipment, records, biosafety and waste disposal.

     iv.If results of earlier validation indicate poor performance of blood film and staining procedures, request microscopist to demonstrate staining and smearing procedures and observe how he/she performs said procedures.

     v.Analyze results of assessment, act on issues presented and make necessary recommendations for further action/s.

c. Feedback and Reporting

     c.1 Discuss findings, comments and recommendations with the microscopist and the head of the facility.

     c.2 Submit the written report to the microscopist and head of the microscopy center not later than 2 weeks from the conduct of the on-site visit, duly signed by the validator supervisor, copy furnished the PHO and CHD.

3. Consolidation of Validation Results Among Health Facilities

3.1 Validators must consolidate the results of validation undertaken among different health facilities under his/her assignment using Form 4. Consolidated Validation Report (Annex 6.5).

3.2 Report must include a brief analysis of results summarizing the key findings, actions taken and recommendations to be further acted upon.

3.3 Submit copies of consolidated reports to CHD, PHO, Provincial Health Team Office (PHTO) and Municipal Health Office (MHO) within 1 month after the validation period.

4. Further Review and Validation by Supervising Validators


In situations where there are disagreements in the results of the validation, a member of the NCG of Trainoirs/Validators within the region should conduct further assessment/review and make the final decision.


Level III. Proficiency Assessment of Provincial/Regional Validators
and Certification of National Core Group of Trainers/Validators


The Level 3 of the QAS requires all provincial/regional validators to undergo proficiency assessments every 2 years by the (RITM-NRL), and the accreditation of the NCGT through the WHO Regional Accreditation and EQA Program every 2-3 years.

1. Proficiency Assessment for Regional/Provincial/Municipal Validators

Validators play a vital role in monitoring the performance of microscopists to ensure that high level of proficiency and high quality of microscopy services are maintained at each level of health care. It is therefore essential for validators to undergo regular proficiency assessment. Each province should identify a candidate validator for proficiency assessment. If there are no candidates, the PHO must coordinate with the CHDs to provide a validator for the province. PHO/CHD-candidate validators must pass the Proficiency Assessment for Validators conducted by RITM-NRL.

     1.1 Candidate medical technologist (regional, provincial and municipal health offices/facilities and other private institutions) for becoming a validator must meet the following minimum requirements:

a. Medical Technology graduate

b. Must have passed the Basic Malaria Microscopy Training conducted by any of the following DOH offices: Infectious Disease Office (IDO), CHD, RITM-NRL within the past 3 years

c. At least 3 years experience working as malaria microscopist

d. Willing to accept responsibility as validator

e. Endorsed by the IDO/CHD/PHO/MHO/Chief of Hospital

f. Holding a permanent position

     1.2 Proficiency Assessment Mechanism

a. Participants read a set of 48 reference slides over a period of 4 days in an independent and blinded manner.

b. Participants are graded on species identification and parasite quantification against the reference readings and classified accordingly as follows:

Grade of >90%                                   

Recommendations:

     Qualified as validator

      To undergo regular assessment every 2 years

Grade of < 90%                                    

Recommendations:

     Continue performing microscopy under the supervision of the regional/provincial validator.

     Recommend for re-assessment after 1 year

2. Certification of National Core Group of Trainers/Validators

     2.1 Certified Regional/Provincial Validators can become a member of the NCG of Trainers/Validators if they meet the following criteria:

a. Endorsed by the IDO/CHD/PHO

b. Willing to accept responsibility as a national validator and trainer

c. Officially designated by the head of office

     2.2 NCG of Trainers/Validators must undergo certification through the WHO Regional Accreditation and EQA Program every 2-3 years to increase and maintain their level of proficiency.

     2.3 NCG of Trainers/Validators must obtain a mark of 90% on detection of parasitemia, 90% on species ID and 50% of the blood films read that fall within + 20% of the true parasite count.


Malaria Microscopy Quality Assurance Forms

Source: Department of Health - Malaria Control Program Manual of Procedures, Guidelines in the Quality Assurance of Malaria Microscopy