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Reporting of Viral Hepatitis Disesase

Reported cases of hepatitis have been classified into hepatitis A, hepatitis B, non-A non-B hepatitis and unclassified (data on hepatitis markers inconclusive) forms since 1988. The criteria of the classification are listed in table 1. This reporting system has documented the incidence of clinical viral hepatitis. The majority were acute hepatitis while a proportion might be acute-on-chronic diseases.

Classification Criteria
Hepatitis A IgM anti-HAV positive
Hepatitis B IgM anti-HBc positive
NANB negative for either of the above two
Unclassified data on hepatitis markers inconclusive

table 1 - classification criteria for the notification of viral hepatitis

The reported incidence of viral hepatitis against time is shown in figure 1 and table 2. It shows that the incidence of hepatitis A essentially dominates that of hepatitis as a whole, accounting for over half of all reported cases each year.
fig 1 - temporal trend of total number of reported case of viral hepatitis

The overall incidence of viral hepatitis was low from 1966 to 1970. A trough occurred in 1970 with a total incidence of only 117. It then gradually increased to 1554 in the year 1980 with two epidemics, in 1972 (729 cases ) and 1975 (1761 cases). A plateau was reached that lasted from 1981 to 1984. A general declining trend was then noted from 1984 to 1995, punctuated by two outbreaks in 1988 (2398 cases) and in 1992 (4357 cases).

year A B NANB Unclassified total
66 voluntary reporting since 1966 386
67   218
68 191
69 188
70 117
71 357
72 729
73 509
74 notifiable since 1974 639
75   1761
76 969
77 1008
78 1230
79 964
80 1554
81 1738
82 1814
83 1783
84 1780
85 1601
86 1425
87 1554
88 1187 250 465 496 2398
89 618 136 154 324 1232
90 1362 178 183 261 1984
91 1297 150 200 154 1801
92 3626 157 301 273 4375
93 874 116 203 80 1273
94 557 112 125 41 835
95 489 99 51 27 666
96 253 153 44 18 479

table 2 - reported viral hepatitis from 1966 to 1995

In the 1992 outbreak of hepatitis A. 3626 cases were reported. A breakdown of age and sex is summarized in figure 2. Clinical cases of hepatitis A occurred predominantly in the age group 20-29 (n=1842, 50.8%). The next age group with high incidence was 10-19 (n=770, 21.2%). Hepatitis A was uncommon in age over 50 (n=15, 0.4%).

age group female male total
0-9 160 203 363
10-19 262 508 770
20-29 627 1215 1842
30-39 161 375 536
40-49 35 65 100
50-59 4 8 12
60-69 0 1 1
70-79 0 1 1
80-99 1 0 1
total 1250 2376 3626

fig 2 - reported incidence of hepatitis A in 1992 by age and sex