Cholera in Zimbabwe: Epidemiological Bulletin Number 10 Week 7 (08-14 Feb 2009) Foreword This is the 10th epidemiological bulletin to be issued since the onset of a countrywide Zimbabwe cholera epidemic first reported in August, 2008. Bulletins are to be published weekly to coincide with the end of an epidemiological week (Sunday to Saturday). Daily cumulative caseload updates are posted on the OCHA website http://ochaonline.un.org/Default.aspx?alias=ochaonline.un.org/zimbabwe 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 Email: [email protected]. Toll free number for alert by district and province is 08089001 or 08089002 or 08089000 Mobile number for alerts is 0912 104 257 Source: Ministry of Health and Child Welfare Rapid Disease Notification System 1 Foreword 1 1. Outbreak summary 3 2. National Overview 4 2.1. Cases and deaths 4 2.2. Mortality 5 2.3. Cholera treatment centres (CTC and CTU) 6 2.4. Surveillance findings by province 7 3. Discussion 12 3.1. Cholera Command and Control Centre Response 12 3.2. Alerts and early warning system 12 3.3. Interpretation 12 3.4. Areas / district needing attention 12 4. Appendix 1: Case definition 14 5. Appendix 2: Weekly cases, deaths and attack rates 15 By week of notification and district from week 5 to 7 15 Source: Ministry of Health and Child Welfare Rapid Disease Notification System 2 1. Outbreak summary Since Aug 2008, some 56 districts (on 62) have experienced cases at one point in time. At the end of week 7 (14 Feb 09), the total number of cases reported since the start reached 75,786 cases and 3,615 deaths. From 08-14 Feb 09, a total of 7,458 suspected cholera cases were reported to the World Health Organization (WHO) through the Ministry of Health and Child Welfare's (MoHCW) surveillance department. This weekly count represents an average of 1,065 new suspected cases reported per day and a 5.3% increase in caseload as compared to the prior week (7,081 cases week 6). A total of 217 deaths were also reported (average 31/day) representing a 0.9% decrease in the deaths count as compared to the prior week (219 deaths week 6). The weekly case-fatality ratio (CFR) 1, based on reported deaths and cases continues to decrease from 3.1% last week to 2.9 % this week whereas the institutional CFR decreased from 1.7% to 1.3%. The proportion of community deaths also remained stable at 44% this week. A total of 372 Cholera Treatment Centers (CTC) and Cholera Treatments Unit (CTU) have been reported to have been established at one point in time, of which 319 are believed to be active as of 14 Feb 2009. In addition to under reporting week 6 and 7, batch back reporting overlapping between week 6 and 7 challenges again trend interpretation. In conclusion, the epidemic is still not under control. The increase in trend observed week 7 could be the reflect of back reports compensating under reporting of the prior week. Still under reporting was significant also this week. Crude and institutional case fatality ratios and proportion of community deaths remain almost unchanged week 7. Adjustment of data for week 6 and 7 is needed to re-estimate trends. 1 the proportion of cases that die of the disease during the time period (here the week) Source: Ministry of Health and Child Welfare Rapid Disease Notification System 3 2. National Overview 2.1. Cases and deaths Suspected cholera cases continue to be reported from all 10 provinces. A total of 59 areas within 56 districts were affected so far (90% of 62 districts affected). Outbreaks are localized by province. Whereas week 6 had seen low reporting level, week 7 experienced large numbers of batch reporting of cases for periods overlapping between week 6 and week 7. Follow-up is needed with the provinces and districts in order to reattribute cases to their week of occurrence and allow analysis trends. From 08-14 Feb 09 (week 7) • 7,458 new suspected cholera cases were reported representing a 5.4% increase compared to week 6 (total case week 6 of 7,081. (Figure 1) • 217 new deaths were reported representing a 0.9 % decrease (219 deaths week 6). • The most affected provinces in terms of weekly caseload were Mashonaland Central (2,016), Manicaland (1,429), Mashonaland West (1,354) and Masvingo (1,306). • The overall number of cases reported from Harare Province was decreasing this week (figure 2) Figure 1 Figure 2 Cholera in Zimbabwe Cholera in Harare province, Zimbabwe 17 aug 08 to 14 Feb 09 17 aug 08 to 14 Feb 09 3,000 10,000 under reporting 2,500 8,000 cases 2,000 Cases deaths Deaths 6,000 1,500 cases 4,000 1,000 Number 500 2,000 0 0 w1 w2 w3 w4 w5 w6 w7 w34 w35 w36 w37 w38 w39 w40 w41 w42 w43 w44 w45 w46 w47 w48 w49 w50 w51 w52 w1 w2 w3 w4 w5 w6 w7 w34 w35 w36 w37 w38 w39 w40 w41 w42 w43 w44 w45 w46 w47 w48 w49 w50 w51 w52 weeks weeks Source: Ministry of Health and Child Welfare Rapid Disease Notification System 4 2.2. Mortality 2.2.1. Differential deaths count Community deaths are defined here as deaths suspected from cholera which occur outside of health facilities. The number of community deaths can reflect how well the population is being covered by the CTC/CTUs. However, interpretation of this figure must be made with caution since verbal autopsies are rarely done to confirm cause of death: some community deaths may not be caused by cholera. Reports of community deaths are not available from all provinces. This week, the percentage of community deaths increased from 44% last week to 55% (119/217) (table 1). Table 1. Proportion of deaths outside cholera treatment centers, week 08-14 Feb 09, selected* provinces Number of Number of Proportion of community Province deaths community deaths death (%) Harare city 1 0 0 Chitungwiza 0 0 - Bulawayo 0 0 - Mashonaland Central 72 24 33 Mashonaland East 9 4 44 Mashonaland West 40 29 72.5 Manicaland 49 46 94 Masvingo 11 6 54 Matebeleland North 5 1 17 Matebeleland South 2 2 100 Midlands 28 7 87.5 Total 217 119 55 *for Harare, deaths outside CTC are irregularly/not reported 2.2.2. Case fatality ratios (CFR) The institutional Case Fatality Ratio 2 decrease from 1.7% to 1.3% and the crude CFR decreased from 3.1 to 2.9 %. Figure 3 Cholera in Zimbabwe from 16 nov 08 to 14 Feb 09 Weekly crude and institutional case-fatality ratios 10 9 CFR 8 iCFR * Probable under reporting of cases and deaths 7 during week 1 (28 Dec08-3Jan 09) during the holiday period 6 * 5 ** Under reporting week 6 and batch reporting percent 4 ** week 7 3 2 1 0 w47 w48 w49 w50 w51 w52 w1 w2 w3 w4 w5 w6 w7 Epidemiological weeks 2 iCFR: estimation of the institutional CFR is based on the assumption that deaths which are not reported as being community deaths occurred at institution level (proxy meant for monitoring of case-management efforts at institutional level). Source: Ministry of Health and Child Welfare Rapid Disease Notification System 5 This week, 15 districts still had a crude CFR>5% (figure 4). 2.3. Cholera treatment centres (CTC and CTU) To respond to the outbreak, a total of 372 Cholera Treatment Centres (CTC/CTU) have at one point been set up around the country, including 319 structures thought to be operating as of 14 Feb 09 (table 2 and fig.5). Figure 4. Location of all the cholera treatment centers (CTC and CTU) in Zimbabwe which have been operating at one point in time, as of 14 Feb 2009 CTC /CTU Operative (319) Closed (53) Table 2. Number of CTC/CTU reported to be active per province, as of 14 Feb 2009 New reported cases during week 7 Average case treated per CTC Operative Community Treated for all by day Area / Province Total CTC Death in CTC* Week 7 of week 7 Harare city 280 0 280 2 140 20 Chitungwiza 92 0 92 1 92 13 Bulawayo 5 0 5 1 5 1 Manicaland 1,429 46 1,383 64 22 3 Mashonaland Central 2,016 24 1,992 43 46 7 Mashonaland East 328 4 324 26 12 2 Mashonaland West 1,354 29 1,325 78 17 2 Masvingo 1,306 6 1,300 60 22 3 Matebeleland North 20 1 19 5 4 1 Matebeleland South 70 2 68 6 11 2 Midlands 558 7 551 33 17 2 Total 7,458 119 7,339 319 23 3 * Cases treated in CTC = All cases - cases resulting in community deaths Source: Ministry of Health and Child Welfare Rapid Disease Notification System 6 2.4. Surveillance findings by province 2.4.1. Attack rates From 08-14 Feb 09 the most affected provinces in terms of attack rates were in cases per 100,000 inhabitant : Mashonaland Central (AR:191), Mashonaland West (AR:104), Masvingo (AR:93) and Manicalands (86).