Cholera in Zimbabwe: Epidemiological Bulletin Number 27

Transcription

1 Cholera in Zimbabwe: Epidemiological Bulletin Number 27 Week 24 (7 to 13 June 2009) Foreword This is the 27 th epidemiological bulletin to be issued since the onset of a countrywide Zimbabwe cholera epidemic first reported in August Bulletins are published weekly to coincide with the end of an epidemiological week (Sunday to Saturday). Daily cumulative caseload updates are posted on the WHO website, and as well as on the OCHA website The bulletin provides a weekly overview of the epidemic in Zimbabwe, including province by province data, to inform and improve the continuing public health response. It also provides guidance to agencies on issues relating to data collection, analysis and interpretation, and suggests operational strategies on the basis of epidemiological patterns so far. The WHO Team welcomes feedback and data provided by individual agencies. Given the scope of this epidemic, errors and omissions are inevitable: we will be grateful for any information that helps to rectify these. Please send any comments and feedback to the Cholera Control and Command Centre Cholera_Taskforce@zw.afro.who.int. Toll free number for alert by district and province is or or Mobile number for alerts is Acknowledgements We are very grateful to MoHCW District Medical Officers, Provincial Surveillance Officers, Provincial Medical Directors, Environmental Heath Officers, and MoHCW's department of surveillance, who have helped to gather and share the bulk of the information presented here. Likewise, we acknowledge agencies, including members of the Health and WASH clusters, who have kindly shared their data with our team. MoHCW has recognized and thanked the efforts made by NGOs assisting in the response and providing support to MoHCW cholera treatment centres (MoHCW 16/12/2008). This document would not have been possible without the contributions of the WHO data management team, who are part of the C4 Cholera Command and Control Centre. 1

2 Figures See also summary tables (annex 1), maps (annex 2) and graphs (annex 3) The case definition can be found in appendix 1 and detailed data by district are shown in appendix 2 Since August out of the 62 districts (89%) in the country have been affected by the ongoing cholera epidemic (see map 3 in annex 2). 98,531 suspected cholera cases and 4,282 deaths have been reported by 13 th of June 2009 to the World Health Organization (WHO) through the Ministry of Health and Child Welfare's (MoHCW) surveillance department. The crude case fatality since the outbreak started still stands at 4.3% (61.4% of the mortality being community deaths). During week 24 (7 th to 13 th June 2009) 22 new suspected cholera cases were reported compared to 38 cases during week 23 (42.1% decrease). No deaths were reported this week compared to three deaths during week 23. On day three of week 24 (Tuesday 9 June) no cholera cases were reported (the first day of national zero report since the peak of the epidemic) At provincial level Four provinces reported cholera cases this week (same as in the previous week) and fewer cases were reported in all the provinces except Mashonaland West which reported 6 cases but had reported zero cases in week 23. Harare province continued to report the highest (weekly) case load (12), accounting for 55% of all the cases reported in the country in week 24, though the cases were lower than those reported in the previous week (21). (See table 1 in annex 1) Matabeleland North and Matabeleland South reported no cases for the tenth cumulative week while Bulawayo also continued to report zero cases for the seventh consecutive week. At district level Ten (10) districts reported new cholera cases this week, a 67% increase from the six (6) districts that reported cases in during week 23. (see table 2 in annex 1 for the districts and numbers of cases reported). Of note this week is that scattered cases were reported in new districts that had not been reporting cholera cases in the recent weeks, these include Makoni, Chipinge, Bikita and Gweru Urban, i.e. Chipinge district and Gweru City reported one case each after going for 9 weeks reporting zero cases. (see table 3 for the number of weekly zero reports prior to this week s cases) Harare City reported the highest case load (11 cases), though the weekly cases continued on a declining trend, from 16 cases in week 23 and 21 cases in week 22. Cases from Chitungwiza district also decreased from five cases in week 23 to one case this week. Reporting The average daily reporting rates have continued on a downward reaching a rate of 58.8% in week 24, the lowest average weekly reporting rate in more than eight weeks. (see graph 6 for the trend in reporting rates over the past two months). Mashonaland West province performed poorly in terms of reporting, failing to submit reports on all the five reporting days during week 24. On each of the last two days of week 24 only half (five) of the ten provinces were submitting daily reports. Among the districts, poor reporting compliance was observed from Gokwe North and South districts which consistently failed to submit reports throughout the week. 2

3 Data interpretation The declining trend in the number of weekly cholera cases continued into week 24, having been on the decline for 18 consecutive weeks. The sustained decreases in the number of cases continue to demonstrate that the cholera epidemic is approaching an end. Of concern this week are the scattered cholera cases that were reported from a number of districts that had gone for weeks submitting zero reports (Chipinge, Makoni, Chimanimani, Bikita and Gweru Urban). Though some of these reports could be true cholera cases, its also highly possible that there could be over-reporting of cholera cases (other diarrhoea causes being captured as cholera) since most of the reported cases are not being confirmed by laboratory examination. This further emphasizes the need to enforce the earlier recommendation that all suspected cholera cases should undergo laboratory confirmation. The persistent decline in the country s average weekly reporting rates is also an area of concern. The concurrent national immunization campaigns could have further lowered the reporting rate for week 24, since the same officers who collect and report cholera data are actively involved in data collection and reporting for the immunization campaign. However there is need to emphasize the importance of maintaining good quality surveillance, especially in this final phase of the outbreak to facilitate the early detection of the possible re-emergence of the cholera outbreak. Response Different organizations continue to support the various technical areas of the cholera response efforts across the country (case management, social mobilization, NFI distribution, drilling boreholes, and trucking of water). This support should be commended and encouraged. The computers donated by the WHO to the MoHCW to strengthen data management continue to be distributed to the provinces and city health departments. The recently donated rapid cholera test kits are still undergoing laboratory evaluation, before they can be certified for wide use in the country. Recommendations The cholera epidemic is evidently approaching an end, but efforts still need to be continued in a few areas. There is need to enforce last week s recommendation that all new suspected cholera cases should undergo laboratory confirmation to rule out other causes of watery diarrhea. This will avoid overreporting of cholera and will assist us in ascertaining the definite end of the cholera epidemic. A communication in that regard has been sent to all provincial and city health C4s but the information needs to be disseminated to the health staffs who are manning the various cholera treatment centres. All provinces should continuously be reminded of the importance of consistently submitting daily updates, including zero reports. The national surveillance unit should also reinforce the system by improving the follow up of poorly reporting provinces and districts. 3

4 Annex 1: Summary Tables Table 1: Cholera cases reported during week 24 and since August 2008 and the attack rates (AR) per 100,000 inhabitants by province in Zimbabwe as of the 13 th of June 2009 Affected Number of cases AR per 100,000 Province Populations(a) WEEK 23 Cumulative WEEK 23 Cumulative Bulawayo 718, Matabeleland North 351, Matabeleland South 331, Mashonaland East 1,317, Midlands 1,464, Mashonaland Central 1,056, Masvingo 1,401, Manicaland 1,665, Harare b 1,891, Mashonaland West 1,300, TOTAL 11,498, , (a) Cumulative population of affected district only; (b) Includes Harare City and Chitungwiza Table 2: Cholera cases reported during week 24 in Zimbabwe by reporting district and province, 7 th to 13 th June Province District Number of Cases Harare Harare City 11 Chitungwiza 1 Manicaland Makoni 2 Buhera 1 Chimanimani 1 Chipinge 1 Masvingo Chiredzi 1 Bikita 1 Midlands Gweru City 1 Gokwe South 2 4

5 Table 3: Table showing districts the reported new cholera cases in week 24 after weeks of zero reporting and the number of weekly zero reports. District Weeks of zero report Chipinge 9 Gweru 9 Makoni 7 Chimanimani 6 Bikita 5 5

6 Annex 2: Maps Map 1 showing the distribution of the new cholera cases that occured during week 24 in Zimbabwe by district (7 th to 13 th of June 2009) Map 2 showing the cumulative cholera attack rates (per 100,000 inhabitants) by district in Zimbabwe, 17 th August 2008 to 13 th June

7 Annex 3: Graphs Graph 1 showing the trends in the number of new cholera cases and deaths reported weekly in Zimbabwe, 17 th Aug 2008 to 13 th June Graph 2 showing a closer picture of the weekly trend in new cholera cases in Zimbabwe in the recent nine weeks (12 th April to 13 th June 2009). 7

8 Graph 3 showing the cumulative number of reported cholera cases by province in Zimbabwe, 17 August 2008 to the 13 th June Graph 4 showing the number of new cholera cases reported each day during week 24 and the daily average reporting rates, 7 th to 13 th June

9 Graph 5 shows the trends in the weekly cholera attack rates for Harare Province (Harare City th th and Chitungwiza town), 5 April to 13 June Graph 6 showing the trend in the average weekly reporting rates over the past seven weeks, number of cholera cases reported from Buhera Rural District in the past thirteen weeks, 2nd April to 13th June

10 Appendix 1: Case definition The Zimbabwe cholera case definition states that "in an area where there is a cholera epidemic, a patient aged 2 years or more develops acute watery diarrhoea, with or without vomiting". A confirmed cholera case is when Vibrio cholerae is isolated from any patient with diarrhoea. This is adapted from the WHO case definition for cholera. The inclusion of all ages in the case definition somewhat reduces specificity, that is, inclusion of more non-cholera childhood diarrhoea cases. It, however, does not impede meaningful interpretation of trends. Teams should monitor any shift in the age distribution of cases, which might indicate a changing proportion of non-cholera cases among patients seen. 10

11 Appendix 2: Cholera in Zimbabwe: Suspected Cases, Deaths, AR, CFR Epidemiologic Week 22 to 23, 2009 Province District Week st May 6 th June 2009 Week 24 7 th 13 th June 2009 Cases Deaths AR/100,000 CFR(%) Cases Deaths AR/100,000 CFR(%) Harare Bulawayo Mashonaland Central Chitungwiza Harare Total Bulawayo urban Bindura Centenary Guruve Mazowe Mt Darwin Rushinga Shamva Total Chikomba Goromonzi Hwedza Marondera Mashonaland East Mashonaland West Mudzi Murehwa Mutoko Seke UMP Total Chegutu Hurungwe Kadoma Kariba Mahombekombe Kariba Rural Makonde Zvimba Source: Ministry of Health and Child Welfare Rapid Disease Notification System 11

12 Total Buhera Chimanimani Chipinge Makoni Manicaland Matebeleland North Matabeleland South Masvingo Midlands Mutare Mutare City Mutasa Nyanga Total Binga Lupane Nkayi Total Beitbridge Gwanda Umzingwane Plumtree Total Bikita Chiredzi Chivi Gutu Masvingo Mwenezi Zaka Total Chirumhanzu Gokwe North Gokwe South Gweru City (Mkoba) Kwekwe Mberengwa Zvishavane Total GRAND TOTAL Source: Ministry of Health and Child Welfare Rapid Disease Notification System 12