MEASLES BULLETIN Progress towards measles elimination in Cambodia, 2000-2004
World Health Organization Regional Office for the Western Pacific Expanded Programme on Immunization
World Health Organization, Western Pacific Regional Office, Manila, Philippines Issue 4 December 2004 immunization activity (SIA) campaign, targeting all children aged 9 months to 14 years old. The campaign was supported by WHO, Australian Agency for International Development, Centers for Disease Control and Prevention, Government of Japan and the United Nations Children’s Fund (total cost approximately US$ 3.0 million). Due to the difficulties in accessing many parts of country and limited skilled human resources and supervision in 2000, the nationwide SIA was conducted in four phases from the end of 2000 until early 2004. Phase I (December 2000-May 2001) targeted children aged 9 months to 4 years in the nine remotest provinces. The measles campaign was combined with oral polio vaccine and vitamin A for children under 5 years, mebendazole for children 1-4 years, tetanus toxoid for child-bearing age women, iodine salt, routine antigens and impregnated mosquito bednets. Phase II (October 2001-April 2002) and Phase III (October 2002-April 2003) targeted children aged 9 months to 14 years in the most populous provinces, combined with vitamin A and mebendazole for children 2-12 years. Phase IV (January-May 2004) supplemented the remote provinces of Phase I and targeted children 7-14 years combined with other services in Phase I, except bednets. The total number of children targeted was 5 084 930 and a total of 5 061 006 children received measles vaccine. The coverage was high in Phase II (98%) and Phase III (103%), reaching 4.5 million children, and low in Phase 1 (80%) and IV (87%), reaching only 570 000 children in the remote provinces; this was mainly due to inaccessible areas with possibly many service combinations. During the measles catch-up campaign, each immunization team targeted 80-150 children per day; they worked at fixed posts in the morning and moved to villages as mobile teams in the afternoon. Due to low school enrollment in rural areas (<50 %), house-to-house activity in the villages was a tough task for vaccinators who had to chase a large cohort of children who were often working in the field, and sometimes running away. After the 2000-2004 measles catch-up campaign, the incidence of reported measles cases showed a significant reduction from 94/100 000 in 2000, to 4.8/100 000 in 2003 (reported 653 cases) to 2.3/100 000 in 2004 (reported 322 cases).
C
ambodia has been heavily endemic with measles for many years with the latest outbreak in 2000 (12 327 cases reported). Despite the Government of Cambodia’s effort to improve routine immunization after recovering from decades of civil war and the latest resurgence of civil unrest in 1997, the measles immunization coverage had reached only 63% (Ministry of Health [MOH] data in 1999). This suggested that the interruption of domestic circulation of measles virus by routine immunization alone has been difficult. In response to the outbreak in 2000, National Immunization Programme Cambodia decided to conduct a nationwide measles catch-up supplementary
However, the underreporting of measles cases is notable, as most of the clinicians and health workers in the provinces do not clearly understand the case definitions of “rash and fever”; rubella was hardly reported in the past. Even after the special emphasis on measles surveillance at the provincial level in 2004, the blood sample collection rate of suspect measles (20%) did not change much between 2003 and 2004. The measles IgM positive rate is declining (75% in 2002, 66% in 2003 to 51% in 2004), and the rubella IgM positive rate is increasing (0 in 2002 and 2003 to 12 % in 2004). These data suggest that surveillance still has a far way to go, but steps are being made towards the elimination goal. The Government of Cambodia is now planning to conduct a followup campaign targeting children under 5 years in 2006.
MEASLES BULLETIN Western Pacific Regional Office Field Guidelines for Measles Elimination
T
he Field Guidelines for Measles Elimination is designed to help countries in the Western Pacific Region move closer to measles elimination. This field guide provides guidance for countries to implement the Western Pacific Regional Plan of Action for Measles Elimination as urged by the 2003 Regional Committee Meeting. The field guide will help countries develop and implement national plans based on the key strategies: immunization, surveillance, and laboratory diagnosis. The field guide provides health workers, immunization programme managers, public health professionals, and policy makers at national and subnational levels with advice on what needs to be done and how to do it. The field guide will be distributed in early 2005.
Country progress towards elimination
W
HO Western Pacific Regional Office was charged to assess countries’ progress towards measles elimination and to set a target date for regional measles elimination [RCM resolution WPR/RC54.R3]. As reported in the last Measles Bulletin, the Measles Task Force has completed these tasks. Table 1 was used as part of the assessment of progress. This data will now be used to assess progress in eliminating measles in accordance with the indicators. The table shows the current status of countries with respect to the regional measles plan’s three strategies: immunization, surveillance and laboratory support. A key requirement for measles immunity is to achieve and maintain very high population immunity (>95%). It is critical to have high population immunity to interrupt transmission of the virus. This immunity is achieved by having high coverage (>95%) with two doses of measles vaccine. At
present, there are data on first dose coverage, delivery of the second dose and campaigns. These data will serve as a foundation for estimating population immunity. Core surveillance functions are case detection, reporting, investigation (including confirmation of diagnosis), analysis, interpretation and dissemination of information. A case-based surveillance system, and analysis of that data is a key requirement. In addition, there needs to be reported indicators of surveillance quality to be sure that zero reports of measles indicate lack of disease rather than poor surveillance (See Measles Field Guidelines for indicators). Laboratory testing to confirm a clinical diagnosis of measles is an essential part of the surveillance system. As the Measles Laboratory Network develops, the requirement will be for an accredited laboratory. In addition, it will be important that most suspect cases are tested to confirm (or discard) a diagnosis of measles.
Table 1. Country progress towards elimination (2004 ) Country Australia Brunei Darussalam Cambodia China Hong Kong (China) Japan Republic of Korea Lao People's Democratic Republic Malaysia Macao (China) Mongolia New Zealand Philippines Papua New Guinea Singapore Viet Nam Pacific island countries Routine immunization Immunization campaigns Access to MV2 MV1 Case-based Reported national Year Target Reported surveillance When coverage Schedule laboratory coverage* introduced 93% 1994 4 yrs 1998 5-12 yrs 96% Yes Yes 99% 1997 10-13 yrs Yes Yes 65% 2000-2004 9 mos-4 yrs 87% Yes Yes 99%∞ 84% 1986 7 yrs 2003 8 mos-12 yrs Planned Yes 81% 1996 6 yrs 2002 ≥11 yrs 99% Yes Yes 99% Sentinel Yes 97.2% 2000 4-6 yrs 2001 8-16 yrs 96% Yes Yes 42% 2001 9-59 mos 86% Yes Yes 92% 2002 7 yrs 2004 Planned Yes 90% 1991 15 mos Yes Yes 98% 1987** 14-21 mos 2000 9 mos-7 yrs 97% Yes Yes 85% 1992 4 yrs 1997 2-10 yrs 75% Yes Yes 80% 2004 9 mos-8 yrs 94% Yes Yes 42%Φ 99%Ω 2003-2004 6 mos-14 yrs No Data Yes 88% 1998** 11-12 yrs Yes Yes 93% 2002-2003 9 mos-10 yrs 99% Yes Yes 82% Variable Variable Variable Subregional Legend for Coverage:
≥ 90% 80% - 90% < 80%
* Based on WHO-UNICEF best estimates ** Part of country only Φ
Supplemental dose at 6 months ∞
one pilot prefecture Ω
three provinces
MEASLES BULLETIN
Republic of Korea evaluates measles elimination programme
T
he International Conference on the 4th Year Evaluation of the Measles Elimination Program was held in Seoul from 23 to 24 November 2004. Participants included the United Nations Children’s Fund, Centers for Disease Control and Prevention, Ministry of Health, Labour and Welfare – Japan and WHO Western Pacific Regional Office. The Republic of Korea has made significant progress towards achieving measles elimination and plans to undertake a final evaluation in 2005. The area of emphasis during this fourth year is enhancing and evaluating measles surveillance after the national measles immunization campaign of 2001. The Republic of Korea started routine two-dose measlesmumps-rubella vaccination with >95% coverage, added a school-entry requirement certification in 2001, held a catchup campaign for children 8-16 years and increased surveillance to monitor elimination. The comprehensive surveillance programme was clearly and precisely delineated and a strict case definition of measles was developed. The country adopted the measles surveillance indicators established by WHO. The progress of the Republic of Korea measles surveillance programme appears in Table 2:
MEASLES BULLETIN Table 3. Measles cases, vaccination status and deaths (as of December 2004)* Classification Reported suspected Laboratory Epi-linked cases confirmed Confirmed cases Incidence rateΦ (Total confirmed) Discarded Pending Suspected cases immunized Ω
Indicators
Clinical
Deaths
Latest date reported to Western Type of report Pacific Regional Office (WPRO)
American Samoa Australia Brunei Darussalam Cambodia China Cook Islands Federated States of Micronesia Fiji French Polynesia Guam Hong Kong (China) Japan Kiribati Lao People's Democratic Republic Macao (China) Malaysia Marshall Islands Mongolia Nauru New Caledonia New Zealand Niue Northern Mariana Islands Palau Papua New Guinea Philippines Republic of Korea Samoa Singapore Solomon Islands Tokelau Tonga Tuvalu Vanuatu Viet Nam Wallis and Futuna Western Pacific Region
33 3 322 0
0 1 61 0
0 0 0 0
26 2 261 0
0.13 (26) 0.84 (3) 2.28 (322) 0.00 (0)
0 0 0 0
0 0 0 0
12% (4) 67% (2) 14% (44) -
0 0 3 -
30-Nov-04 12-May-04 15-Nov-04 08-Dec-04
case data case data case data aggregate
61
-
-
-
0.87 (61)
0
0
-
-
30-Dec-04
aggregate
1340 2
-
-
-
23.69 (1340) 0.43 (2)
0 0
0 0
-
10 -
15-Sep-04 12-Nov-04
aggregate aggregate
36
2
0
0
0.08 (2)
34
0
-
-
06-Dec-04
case data
26
-
-
-
0.67 (26)
0
0
-
-
20-Dec-04
aggregate
2872 55 0 96
23 10 0 -
6 0 0 -
1651 0 0 -
2.10 (1680) 0.02 (10) 0.00 (0) 2.26 (96)
1192 39 0 0
0 6 0 0
23% (665) 11% (6) -
16 0 0 -
28-Dec-04 23-Nov-04 08-Dec-04 31-Dec-04
case data case data aggregate aggregate
767 5613
29
21
13
0.08 (63) 1.36 (3631) Φ
633
71
48% (371) 19% (1092)
0 29
24-Nov-04
case data
* Data are based on country reports and other sources available to EPI/Western Pacific Regional Office. Incidence rate per 100 000 population (World Population Prospects: The 2002 Revision, New York, United Nations, 2002). Ω
Suspected cases immunized does not distinguish between 1 or 2 doses.
Comments may be sent to Dr Ernest Smith smithe@wpro.who.int or Ms Margaret Hercules herculesm@wpro.who.int Please send quarterly data to Mr Dexter Bersonda at bersondad@wpro.who.int WORLD HEALTH ORGANIZATION Regional Office for the Western Pacific United Nations Avenue P.O. Box 2932 1000 Manila, Philippines Fax No. (632) 5211036, 5260279, 5260362 Tel. No. (632) 5288001