The results of AFP investigations can be summarized using clinical and virologic classification schemes. For the Macau Eradication Program, all results should consider the virologic scheme. The criteria to move from clinical to virologic scheme are the following:

non-polio AFP rate >1/100,000 children less than 15 years of age;

two adequate stool specimens collected on >80% of AFP cases; and

all specimens collected in Macau (hospitals) should be processed in the WHO-accredited laboratory in Hong Kong (Queen Mary Hospital).

Clinical classification scheme:

1. Died or lost to follow-up?  (yes)→ Confirm

2. Follow-up at 60 days?  (yes)

2.1. Residual paralysis?  (yes)→ Confirm

2.2. No residual paralysis?  (yes)→ Discard

Virologic classification scheme:

1. Wild poliovirus?  (yes)→ Confirm

2. No wild poliovirus?  (yes)

2.1. Adequate specimens?  (yes)→ Discard

2.2. Inadequate or no specimens?  (yes)

2.2.1. no residual weakness?  (yes)→ Discard

2.2.2. residual weakness, died or lost to follow-up?  (yes)

2.2.2.1. "expert" review?  (yes)→ Discard or Confirm

Adequate specimens:

The criteria for "adequate" specimens are the following:

1. Two stool samples should be collect from each AFP case;

2. Stool samples should be collect 24-48 hours apart;

3. Stool samples should be collect within 14 days after onset of paralysis or weakness;

4. Stool samples should arrive in "good condition" to the WHO-accredited laboratory in Hong Kong:

a) inside isothermal containers with ice or frozen ice-packs present, and

b) without leakage or desiccation;

5. Stool samples should be in sufficient quantity for complete analysis (at least 8 grams of stools for each sample); and

6. Stool samples should be accompanied by the specific documentation (prepared by the CEP coordinator in each hospital).

Case classification flowchart (general)

Case investigation flowchart (general)

© Fernando Costa Silva, 1999