cholera in zimbabwe: epidemiological bulletin number 6 · source: ministry of health and child...

Source: Ministry of Health and Child Welfare Rapid Disease Notification System 1

Cholera in Zimbabwe: Epidemiological Bulletin Number 6 Week: 11 Jan 2009- 17 Jan 2009

Foreword This is the 6th 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


Foreword 1 1. Outbreak overview 3 2. Background 4

2.1. Cholera treatment centres (CTC and CTU) 4 3. National Overview 5

3.1. Number cases and case-fatality 5 3.2. Attack rates and proportion of cases per district 7 3.3. Community deaths 9 3.4. Reporting completeness 10

4. Surveillance findings by province 11 4.1. Harare 13 4.2. Bulawayo 13 4.3. Mashonaland West 13 4.4. Mashonaland Central 13 4.5. Mashonaland East 13 4.6. Midlands 13 4.7. Masvingo 14 4.8. Manicaland 14 4.9. Matabeleland South 14 4.10. Matabeleland North 14 4.11. Cholera Command and Control Center Response 16 4.12. Alerts and early warning system 16

5. Acknowledgements 16 6. Appendix 1: Case definition 17


1. Outbreak overview More cholera cases and deaths were reported in the epidemiologic week 11/01/09 - 17/01/09 than in any previous week since the start of the epidemic. The cholera outbreak is not yet under control and all ten provinces are reporting cases. To date (17 January 2009), a cumulative total of 44 272 cases (average 634 per day) and 2332 deaths (average 35 per day) have been reported to the World Health Organization (WHO), through the Ministry of Health and Child Welfare's (MoHCW) surveillance department. The weekly reported cases and deaths have increased for 2 consecutive weeks. 54 of 62 (87%) districts have reported cases to date. Case-fatality rates (CFR, the proportion of cases that die of the disease) based on reported deaths and cases remained high this week at 6.5%. This CFR is still much higher than is targeted in a cholera outbreak (<1%). A total of 235 Cholera Treatment Centers (CTC) and Cholera Treatments Unit (CTU) have been reported to have been established. This week (11 Jan -17 Jan 2009) over two-thirds of deaths (69%) are occurring outside treatments centre suggesting continued, and perhaps increasing, problems associated with the unavailability of health care in the country. The highly affected provinces this week are:

1. Masvingo (increasing cases; high attack rate; CFR > 5%) 2. Manicaland (increasing cases; high attack rate; CFR > 5%) 3. Matebeleland North (first report of substantial numbers of cases; CFR > 5%) 4. Midlands (increasing cases; CFR > 5%) 5. Mashonaland Central (increasing cases; high attack rate) 6. Mashonaland West (CFR > 5%; high attack rate) 7. Mashonaland East (CFR > 5%)

The outbreaks in Harare and Chitungwiza appear to be on the decline, with comparatively low case-fatality.


.

2. Background 2.1. Cholera treatment centres (CTC and CTU)

There are 235 Cholera Treatment Centres (CTC/CTU) distributed over the country, 117 (49%) of which are run only by the MoHCW. The others are run by MoHCW with support from NGOs and/or partners. On average, one CTC/CTU is covering a population of 53,451 persons with noted larger catchments in Harare and Bulawayo. Table 1. Number of CTC/CTU per province, as of Jan 17th, Zimbabwe Province Population Number of CTC Harare (Harare city + Chitungwiza) 2,012,784 3 Bulawayo 718,278 1 Manicaland 1,665,451 46 Mash Central 1,056,666 25 Mash East 1,196,772 26 Mash West 1,300,012 75 Masvingo 1,401,672 36 Mat North 693,230 7 Mat South 748,317 4 Midlands 1,554,058 12 TOTAL 12,347,238 235

Figure 1: Location of the cholera treatment center (CTC and CTU) in Zimbabwe, as of 10 Jan 2009

Figure 2: Location of the 2 cholera treatment centers (CTC) among Harare city suburbs, as of 17 Jan 2009


3. National Overview 3.1. Number cases and case-fatality

For the week 11/01/09 - 17/1/09, 6466 new cases of cholera were reported, an increase from the 4596 cases reported last week. New deaths from cholera reported this week were 420 (an increase from the 272 last week). Cases of cholera continue to be reported from all 10 provinces (8 rural provinces and 2 urban provinces-Harare and Bulawayo), although outbreaks are localized by province and vary in their characteristics. Figure 1 demonstrates the cholera cases reported nationwide. This week data provide continued evidence that week 28 Dec-3 Jan (Christmas and New year’s holidays period) was an artefact of low reporting in the surveillance. Case-fatality rates (CFR, the proportion of reported cases that die of the disease) based on reported cases remained very high this week to 6.5%, and remains far above the <1% target. Figure 1 illustrates the CFR by week nationwide.

Budiriro polyclinics

Beatrice hospital


Figure 3 : New cholera cases, with case-fatality rates, by week. Zimbabwe, Nov 08–17 Jan 09 * For week 7-13 December, gaps in reporting of data were noted. ** For week 28 December 08- 3 January 09, probable under reporting of number of cases and death during the Christmas- New Years holiday period

0

1

2

3

4

5

6

7

8

9

10

0

1000

2000

3000

4000

5000

6000

700016

-22

Nov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR

The method of calculating CFR being used is: total deaths reported (institutional and community deaths) / total cases reported. This has the same meaning as “lethality”. CFRs vary by district and reflect issues of access to care, quality of care, and underlying prevalence of co-morbid conditions such as HIV/AIDS and malnutrition and efficiency of reporting. The number may not accurately reflect the quality of care once admitted to a treatment facility, as deaths in the community (not admitted) have been included in the calculation. In some districts, cases in the community are included in the total number of cases so the calculation of the institutional CFR and the comparison between institutional CFR and community CFR are not appropriate given how the data are collected. On average since November 16th 2008, 587 cases per day and 31 deaths per day are reported with a peak of 819 cases per day in 21-27 Dec 2008 and 52 per day in 14-20 Dec 2008. Table 6. Average cases and deaths per day, from week 16/11/08 - 22/11/08 to week 04/01/09 - 10/01/09, Zimbabwe Week Cases Deaths CFR (%) Cases per day Deaths per day 16-22 Nov 2008 2863 99 3.5 409 14 23-29 Nov 2008 3254 136 4.2 465 19 30 Nov 6 Dec 2008 4499 159 3.5 643 23 7-13 Dec 2008 2841 257 9.0 406 37 14-20 Dec 2008 5379 367 6.8 768 52 21-27 Dec 2008 5730 358 6.2 819 51 28 Dec 08-3 Jan 09 3690 79 2.1 527 11 4-10 Jan 2009 4594 272 5.9 656 39 11-17 Jan 2009 6466 420 6.5 924 60

**

*


The figure below shows the cumulative CFR by district since the onset of the epidemic. Most affected districts have high (>5%) overall rates of death among cholera cases (CFR). Districts with cumulative CFRs over 1% are in all 10 provinces. Figure 4: Cumulative case-fatality rates, by district. Zimbabwe, as of 17 Jan 2008

no cases/deaths01.1 - 5.0above 5

3.2. Attack rates and proportion of cases per district

Attack rates (AR, total number of cases/population) are a measure of the incidence of infection. An AR of 0.6-1.0% is often seen in cholera endemic areas with poor sanitary conditions. The ARs shown here are subject to surveillance bias (higher in areas with better reporting), and are not specific for particular populations at higher risk. Variations in CFR would be expected to occur within districts. The AR is based on district population projections for 2008.


Figure 5. Attack rates by district.: from 11 Jan 2009 to 17 Jan 2009

The most affected provinces for this week in term of attack rates are Masvingo (AR= 0.13%), Mashonaland West (AR= 0.095%) and Mashonaland Central (AR= 0.065%). The following districts had the highest attack rates: Bindura 0.020% and Makonde 0.028% (Mashonaland Central) and Kariba Mahombekombe 0.026% (Mashonaland West)); Binga (Matabeleland North (0.030%), Bikita 0.044% Cheredzi 0.023% (Masvingo). Figure 6. Cumulative attack rates by district. From start of the epidemic to 17 Jan 2009

Attack Rate (per 100,000)

00.1 - 99.9100.0 - 499.9500.0 - 999.91,000 and above


This week, 40% of new cases were reported from Masvingo, followed by Mashonaland West (27%) and Manicaland (19%). Since the beginning of the outbreak, most of the cases are coming from Harare (27%), then Mashonaland West (24%). Table 9. Attack rate (AR) per 100 000 inhabitants by provinces, Zimbabwe, as of 17 Jan 2009

Provinces Population

Number cases week (11 Jan-17 Jan 09)

Cumulative number of cases (since beginning of data collection)

Weekly AR (per 100 000)

Cumulative AR (per 100 000

Harare (Harare city+ Chitungwiza) 2,012,784 330 12099 16 601 Bulawayo 718,278 8 391 1 54 Manicaland 1,665,451 865 5340 52 321 Mash Central 1,056,666 687 1546 65 146 Mash East 1,196,772 218 3860 18 323 Mash West 1,300,012 1,236 10404 95 800 Masvingo 1,401,672 1,858 4423 133 316 Mat North 748,317 385 4470 51 597 Mat South 693,230 198 387 29 56 Midlands 1,554,058 681 1352 44 87 TOTAL 12,347,240 4,594 44272 37 359

3.3. Community deaths 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/CTU's. However, interpretation of this figure must be made with caution since verbal autopsies are not always done to confirm cause of death. Reports of community deaths are not available from all provinces and if available are reported sporadically. For the epidemiologic week 011/01/09 - 17/1/09 reports available are found in Table 1. The figures suggest that the continued problems are associated with the unavailability of health care, mainly because of human resources (nurses are paid as of today, one dollar a month). The proportion of deaths occurring outside treatment centres, per week, could in any site be used as a useful proxy indicator of coverage: the target should be 0%. This week, without taking into account Harare, where community deaths are irregularly (or even not) reported, more than 2/3 of the deaths (69%) are occurring outside treatments centre. In many provinces more deaths are recorded in the community than in the treatments centres. The proportion of deaths occurring in the community has increased this week which may reflect increased difficult for patients to access adequate care or may reflect a relatively improved CFR for institutional cases. Given the data currently available, it is no possible to know which is a more likely explanation.


Table 11. Proportion of deaths that occur outside cholera treatment centres, week 04/01/08 - 10/01/09, selected* provinces *(as for Harare, deaths outside CTC, which are called community deaths, are irregularly/not reported)

Province Deaths within treatment centres

Deaths outside treatment centres

Proportion of deaths occuring outside treatment centres (%)

Bulawayo 1 1 50 Mashonaland Central 7 20 74 Mashonaland West 18 78 81 Manicaland 18 54 75 Matebeleland North 29 0 0 Matabeleland South 3 4 57 Masvingo 40 93 70 Midlands 8 31 79 Mashonaland East Total 124 281 69

3.4. Reporting completeness Figures contained in this report are from all data reported for the reporting week. The date since last report represents the number of days of missing data for a district at the end of the week. Reports were complete (0 days missing) for 45% of districts, missing for: 1 to 2 days for 29% of districts, 3 to 6 days for 22% of districts and missing completely for 3% of districts (Figure 7). On average 45% of districts reported each day, with particularly poor on Sunday (27%). Figure 7. Days since last report (as of 17 Jan 09) of districts by province

0%

20%

40%

60%

80%

100%

≥ 7

3 to 6

1 to 2

0


4. Surveillance findings by province Figure 8a-k: Figure 22. New cholera cases and deaths with case-fatality rates, by week, 16 Nov- 17 Jan* *except Chitungwiza where data are from 17 Aug Note that the scale of y-axes (cases, deaths and CFR) differ by province

A) Chitungwiza* B) Harare City

0

5

10

15

20

25

30

35

40

45

50

0

50

100

150

200

250

17-2

3 Au

g

24-3

0 Au

g

31 A

ug-6

Sep

7-13

Sep

14-2

0 Se

p

21-2

7 Se

p

28 S

ep -4

Oct

5-11

Oct

12-1

8 O

ct

19-2

5 O

ct

26 O

ct-1

Nov

2-8

Nov

9-15

Nov

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR

0

5

10

15

20

25

0

500

1000

1500

2000

2500

3000

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR

C) Bulawayo D) Mashonaland West

0

5

10

15

20

25

30

0

20

40

60

80

100

120

140

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR

0

1

2

3

4

5

6

7

8

9

0

500

1000

1500

2000

2500

3000

3500

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

esCasesDeathsCFR

E) Mashonaland Central F) Mashonaland East

0

5

10

15

20

25

0

100

200

300

400

500

600

700

800

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR

0

5

10

15

20

25

30

35

40

45

50

0

100

200

300

400

500

600

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR


G) Midlands H) Masvingo

0

2

4

6

8

10

12

14

16

0

100

200

300

400

500

600

700

800

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR

0

5

10

15

20

25

30

35

0

200

400

600

800

1000

1200

1400

1600

1800

2000

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR

I) Manicaland J) Matabeleland South

0

5

10

15

20

25

30

35

40

0

200

400

600

800

1000

1200

1400

1600

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR

0

5

10

15

20

25

0

200

400

600

800

1000

1200

1400

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR

K) Matabeleland North

0

1

2

3

4

5

6

7

8

0

50

100

150

200

250

300

350

400

450

16-2

2 N

ov

23-2

9 N

ov

30 N

ov -

6 D

ec

7-13

Dec

14-2

0 D

ec

21-2

7 D

ec

28 D

ec-3

Jan

4-10

Jan

11-1

7 Ja

n

CFR

Cas

es

CasesDeathsCFR


4.1. Harare Harare reported 330 cases this week, down from 501 cases reported last week and deaths decreased from 10 last week to 1 this week. The global data for Harare will be not presented using an epidemic curve from now on, as it doesn’t reflect adequately the separate epidemics occurring in Harare. The data analysis for Harare is separated into Harare City and Chitungwiza, the Harare satellite town. For the first time, we report figures on the evolution of the outbreak for all affected Harare suburbs Despite more suburbs reporting cases in the past week, there we in fact fewer cases, see Figure 10 4.1.1. Chitungwiza Chitungwiza is the Harare satellite town located South West. In August 2008, an outbreak was reported in St Mary's and Zengeza sections of Chitungwiza (population 320 000), about 25 Km south of Harare city centre. Altogether 118 cases were treated, and the outbreak lasted 4 weeks. A second outbreak in Chitungwiza began in November and continues even thought numbers are decreasing. This week 36 cases and 0 deaths were reported, representing a stable number of reported cases and an increase in CFR compared to the previous week (82 cases and 6 deaths, CFR=7.3%). (See Fig 9a)

4.1.2. Harare City In Harare City, 294 cases and 1 death (CFR=0.3%) were reported, representing an decrease in cases (from 419) and CFR (from 0.9%) from the previous week. (See Fig 9b). The CFR data for Harare reflects irregular reporting of community deaths.

4.2. Bulawayo Bulawayo is the second major town in Zimbabwe after Harare. It should be noted that Bulawayo is one of the few towns/cities in Zimbabwe where ZINWA, the national water agency is not in charge of water supply. Bulawayo continues to report a low number of cases (8) from 8 last week. There were 2 deaths, the first reported for 3 weeks. The high CFR for this week in the figure below is based on a small number of cases (in the denominator). (See Fig 9c)

4.3. Mashonaland West This week 1236 cases were reported from Mashonaland West, a decrease from the 1565reported last week. Deaths decreased somewhat from 117 to 92. The weekly CFR is stable and higher than the 1% target : 7.4% this week (7.5% last week). (See Fig 9d)

4.4. Mashonaland Central Cholera cases reported from Mashonaland Central have been increasing for 4 weeks now: an increase this week to 687 (278 reported last week). 27 deaths were reported resulting in a stable CFR of 3.9% (in comparison of CFR=3.6% last week). (See Fig 9e)

4.5. Mashonaland East Mashonaland East reported 218 cases and 18 deaths a decrease in from 401 cases reported last week. The CFR (8.3%) increased from 4.7% last week. (See Fig 9f)

4.6. Midlands Midlands reported 681 cases and 39 deaths (CFR=5.7%), representing a fourfold increase in the number of cases from last week (cases 172, deaths 16) The CFR decreased from 9.3% to 5.7% this week. (See Fig 9g)


4.7. Masvingo Cases reported from Masvingo increased markedly this week (1858 this week in comparison with 448 last week). Deaths increased to 133 (from 77 deaths last week). CFR increased too from 6.0% last week to 7.1% this week. (See Fig 9h)

4.8. Manicaland New cases reported from Manicaland rose slightly this week to 865 from 783 last week. Deaths also increased slightly (72 this week from 62 last week), resulting in a marginally higher CFR of 8.3% (last week 7.9%). (See Fig 9i)

4.9. Matabeleland South Matabeleland South province includes Beitbridge, which is a bustling town on the border with South Africa. Many residents of Beitbridge are working in Musina in South Africa. (See Fig 9j) For this reporting week Matabeleland South reported reduced cases (from 438 to 198 this week) and a decrease in the number of deaths (from 11 to 7 deaths this week), resulting in a slight increase of the CFR (from 2.5% to 3.5% this week).

4.10. Matabeleland North 385 cases and 29 deaths (CRF = 7%) were reported this week from Matabeleland North. Prior to this week only 2 cases and been reported. Therefore, this is the first report confirming that the cholera outbreak is affecting Matabeleland North. However, we suspect the apparent sudden increase may in part be a result of delays in previous weeks in reporting cases . (See Fig 9k)


Figure 9. Spatial distribution of cholera cases in Harare suburbs from 26 Dec 08 to 17 Jan 09 26-27 December 2008

28 Dec 2008 to 3 Jan 2009

4 Jan to 10 Jan 2009

11 to 17 Jan 2009


Discussion

4.11. Cholera Command and Control Center Response

• Daily alter system provided identification of hot spots, follow-up was done by the SOP. Partners reported and were sent supplies accordingly in a number of districts.

• Experts from ICCDRB (Bangladesh) arrived and were deployed to Mashonaland West and a (hotspot In Binga) Matabeleland North and Matabeleland South to assess and advise on case management.

• WHO Senior Epidemiloogist went to Masvingo province to assess the severely affected Bikita and Chiredzi districts.

• UNICEF/WHO/MOHCW formed a committee to receive requests from partners to avoid duplication of responding to requests.

• NatPharn has been strengthened with logistical support (including computers, etc) in order to distribute supplies.

• Laboratory teams (supported by ICCDRB experts) have taken samples from a number of CTUs and have confirmed cases and begun antibiotic resistance profiling.

4.12. Alerts and early warning system

A simple early warning system continues in place using data reported daily by MoHCW officers from districts and provinces. A new criteria has been added this week “Districts with cases re-occurring after more than 14 days”. Four criteria for prioritizing high priority districts for investigation are currently as follows:

• Daily reported cases>30 • Daily CFR >5% • Daily number of deaths outside health facility/CTC/CTU of more than 3 • Districts with cases re-occurring after more than 14 days

Districts crossing any of the above thresholds are prioritized for response activities.

5. Acknowledgements We are very grateful to MoHCW District Medical Officer, Provincial surveillance officers, especially Provincial Medical Director and Environmental Heath Officer, and MoHCW's department of surveillance, who have helped to gather and transmit 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 to the 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 Center.


6. Appendix 1: Case definition The cholera control guidelines for Zimbabwe state that the definition of suspected cholera cases is "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 cases is “when Vibrio cholerae is isolated from any patient with diarrhoea”. This is adapted/modelled after the WHO case definition for cholera. Including all ages in the case definition somewhat reduces specificity (i.e. more non-cholera childhood diarrhoea cases are included), but essentially does not impede meaningful interpretation of trends. However, teams should monitor any shift in the age distribution of cases, which might indicate a changing proportion of non-cholera cases among patients seen. However, up to this point in the outbreak, we have been collecting data from all patients regardless of age. This is because we collect aggregate data every day which does not include ages. Data is also reported via line lists which do include ages. This information takes more time to come in, but in the future we aim at analysing data by age and separate out the <2 year olds at that point for official reporting. So while respecting the case definition for Zimbabwe, we continue to collect case data for all ages to avoid delay in responding to the current outbreak.

cholera in zimbabwe: epidemiological bulletin number 6 · source: ministry of health and child...

Documents