ethics

Emerging Problems in Infectious Diseases Zimbabwe experiences the worst epidemic of cholera in Africa

Peter R. Mason Biomedical Research & Training Institute and the University of Zimbabwe College of Health Sciences, Harare, Zimbabwe

Abstract A severe outbreak of cholera has been reported in Zimbabwe since mid 2008, with so far over 92,000 cases and over 4,000 deaths. This

outbreak has differed from previous outbreaks in being mainly urban and with a high case-fatality rate. Breakdown in the supply of clean

water has been the main underlying cause but breakdown in health service delivery in Zimbabwe has also contributed to the magnitude and

severity of the outbreak.

Keywords: cholera, epidemic, Zimbabwe J Infect Developing Countries 2009; 3(2):148-151.

Received 18 February 2009 - Accepted 25 February 2009

Copyright © 2009 Mason. This is an open-access article distributed under the Creative Commons Attribution License, which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

Cholera is endemic in a number of countries in

southern Africa, and minor outbreaks have been

recorded in Zimbabwe many times in the past. These

outbreaks have usually occurred in communities that

border endemic regions, particularly in the provinces

of Manicaland and Mashonaland East, on the border

with Mozambique. Outbreaks have increased in

frequency and severity in the past 15 years, and have

become more difficult to control. The first large

outbreak of cholera was reported in 1992, in

Manicaland and Mabvuku/Tafara – suburbs on the

eastern edge of Harare - with just over 2,000 cases

and a mortality of 5%. The following year there were

5,385 cases and 381 (6%) deaths. The next outbreak

in 1998 had more than 1,000 cases and 44 deaths, and

the following year there were 5,637 cases with 385

deaths. Most of these cases were in Chipinge and

Chiredzi, in the south-east of the country again close

to the Mozambique border. During 2002, 3,125 cases

were reported in Manicaland and Mashonaland East,

including 192 fatalities. In October 2003, 304 cases

with 11 deaths were reported in Kariba, on the border

with Zambia, and a further 99 cases, 16 of them fatal,

were reported from Binga, a small fishing community

on the shore of Lake Kariba. The Binga cases

probably originated in Kariba, and the high mortality

was probably related to the difficulty of

communications – six people had already died before

the outbreak came to the attention of the health care

authorities. The common feature of all of these

outbreaks was that they occurred in border

communities and were therefore probably imported

from endemic regions in surrounding countries.

While they were serious outbreaks, they were

contained within a short time because of an effective

and efficient response by the health care system.

Thus, while they were unwelcome incidents, they

posed little threat to the wider communities of

Zimbabwe.

During the past 5-10 years, the health system in

Zimbabwe has been compromised by critical

shortages of finance and declining infrastructure. Key

health personnel have become demoralized by poor

pay packages and their inability to practice their

medical professions because of shortages of

diagnostics, drugs and support systems. Many health

professionals have left Zimbabwe, leading to a

critical shortage of human resources especially in the

Mason – Zimbabwe experiences the worst epidemic of cholera in Africa J Infect Developing Countries 2009; 3(2):148-151.

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periphery. Many of the clinics established in rural

areas during post-independence development are no

longer functioning. Even in larger urban areas, health

care has been dramatically compromised by the

economic crisis in Zimbabwe. A number of District

Hospitals have been closed in the past few months,

and services at Referral Hospitals in major cities have

been severely limited. The surveillance and

monitoring of disease outbreaks depends to a great

extent on having personnel in place at functional

community health care clinics, so surveillance has

also been severely compromised – to the extent that

data completeness is estimated to be only 30%.

The current outbreak of cholera that began in

mid-2008 is different from previous outbreaks in a

number of ways. This is by far the largest and most

extensive outbreak of cholera yet recorded in

Zimbabwe and indeed in Africa. Unlike previous

outbreaks, most cases have appeared in urban centres,

far from the borders with endemic neighbouring

countries. Indeed, there is much evidence that

Zimbabwe is now a source of cholera infection for

other countries in the region. Understanding the

reasons for this dramatic shift in epidemiologic

characteristics will need intensive research, but the

current pressures are first to try to contain the

epidemic and to reduce the high mortality, and there

has been only limited investigation. In this report, I

will present some of the epidemiological data; later

we expect to have more information from

microbiological studies

Initial outbreak The present outbreak started in mid-2008 with

the first cases, reported on 20 August, from St.

Mary’s and Zengeza wards of Chitungwiza, a large

urban centre on the outskirts of Harare. This

outbreak, with 118 cases, was well managed and

quickly brought under control through effective

diagnosis and treatment. Although most cases were

diagnosed clinically, Vibrio cholerae was isolated

from 18 (30%) of 59 specimens submitted for

examination, thus supporting the clinical evidence for

an outbreak of cholera. Following this initial

outbreak, a second wave of infections was reported a

few months later. This outbreak occurred more

widely within Chitungwiza, with numerous wards

being affected. By 20 December there were over 600

cases and 104 deaths in the city. The case fatality

ratio in this outbreak was extremely high at 15%, a

situation attributed to the breakdown of health

services in urban areas as result of the economic

crisis in Zimbabwe, and rapid transmission of

infections to people who were already under stress

from hunger.

Both of these outbreaks occurred in urban areas,

with no obvious direct connections to countries

where cholera was endemic, though the initial import

into the community may well have been from a

visitor or recent traveler.

Fig 1. Emergence of cholera in Zimbabwe: Cumulative

cases August 2008-February 2009

Spread through Zimbabwe

Following these urban outbreaks, new cases

were reported with increasing frequency from rural

communities in different provinces. Large outbreaks

were recorded in Beitbridge, on the border with

South Africa, during November 2008 and in Norton,

a small town west of Harare in December 2008.

Cases were, however, appearing countrywide, and by

the end of December 2008, cholera had been reported

from all 10 provinces in the country. As noted above,

spread to South Africa, Mozambique, Botswana and

Zambia is also suspected to have occurred – all four

countries have reported cases of cholera and cholera

deaths in districts that border Zimbabwe. The data

from the provinces are shown below; the importance

of large outbreaks in urban areas of Harare is quite

clear.

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Mason – Zimbabwe experiences the worst epidemic of cholera in Africa J Infect Developing Countries 2009; 3(2):148-151.

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Fig 2. Cases of cholera reported in different provinces

August- December 2008

Transmission Cholera is transmitted mainly through

contaminated water and food, and the breakdown in

water supply and sewerage disposal in urban areas is

believed to be the underlying cause for the rapid

emergence of cholera in the cities. The transfer of

responsibility for water supply and sewerage disposal

from City Councils to the Zimbabwe National Water

Authority (ZINWA) has been closely linked to the

current outbreak. Since the transfer of responsibility,

parts of Harare and Chitungwiza have been without

running water for more than 2 years. People have

become dependent on shallow wells that may become

readily contaminated because of the lack of sewage

disposal. Although ZINWA has promised on many

occasions to correct the supply problems, lack of

finance from central government (and possibly other

factors concerning management shortcomings) has

limited their ability to do this. At present,

international donor agencies are providing support to

try to improve the water supply situation. In the long

run, these measures may be able to control the

epidemic.

Vibrio cholerae has been isolated from more

than half of the suspect cases tested, with at least two

serotypes involved in the outbreak. Serotype Ogawa

has been described in isolates from Harare and

Beitbridge (Matabeleland south), while both Ogawa

and Inaba serotypes have been found in Mashonaland

West (Chegutu and Makondi districts). Molecular

studies are expected to add to our understanding of

epidemiological patterns and virulence factors in the

outbreaks in different parts of the country, and we

hope that such studies can be undertaken soon, using

isolates collected during the outbreak.

Cholera fatalities Case fatality ratios (CFR) in most districts

exceed 5%, based on cases recorded at health clinics.

Outside of the clinics, community fatality ratios are

estimated by WHO to be 22-48%. In most provinces

about 40% of all cholera deaths occur in the

community, and the figures on case fatality may need

to be adjusted accordingly. The CFR in most

outbreaks around the world is about 1%. A number

of factors have been put forward as possibly

contributing to such high CFR, including bacterial

virulence factors, poor nutrition and poor immunity

of infected persons, delays in diagnosis, and

difficulties of accessing appropriate treatment.

Death from cholera is usually a result of dehydration,

and fatalities can often be prevented by the use of

oral rehydration salts (ORS). The main problem

facing infected people in Zimbabwe is lack of access

to ORS – whether at the clinic or at home. The

economic collapse in the country has meant that

clinics and hospitals are no longer able to acquire and

stock even basic medicines and materials to provide

health care. Even though basic ORS packs would be

relatively inexpensive, they are not available. Many

of the clinics in rural areas are closed, because there

are no staff, so patients have to travel to clinics in

urban areas for treatment. The cost of transport is

often beyond the means of the rural poor, leading to

delays in accessing health care. The alternative is to

use home-based ORS. In the past, many health

education programs highlighted the way to prepare

ORS at home, mainly to support home-based

management of diarrhea in children. Sadly, the costs

of the simple basic ingredients of ORS – salt, sugar

and clean water – are also beyond the means of many

in the current economic situation.

The future Understanding why this situation happened may

help in making decisions about how to control and

prevent further epidemics. Outbreaks of cholera have

been reported many times in the past in Zimbabwe,

but until now all have been focal outbreaks and have

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

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Cases

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been contained quickly. The current outbreak has

been continuing for at least six months and so far

shows no sign of abating, with hundreds of new cases

and many fatalities reported daily. The loss of life –

over 3,500 people have died so far – has reminded all

involved in health care that even those diseases that

we thought we could control may return with a

vengeance, if circumstances permit it.

The breakdown in water supply and sewerage disposal in high density urban areas was

undoubtedly a main factor in the emergence and

rapid spread of infections. While economic

factors may be important contributors to this

breakdown, there is also the inability of ZINWA

to deliver the service with which they were

entrusted – the supply of safe water to residents

of major towns and cities. An investigation into

the operations of ZINWA is needed to identify

failures and ensure that such failures do not

recur. The decision by central government to

remove responsibility for urban water supply

from ZINWA and return responsibility to city

councils is a step in the right direction.

The breakdown in health service facilities, with shortages of clinic staff, was a major factor in

delaying detection and management of cases, and

contributes to the high case-fatality ratio

experienced in this epidemic. Attempts are

currently being made to provide more realistic

pay and conditions of service for health care

personnel, to retain the staff who remain.

Assistance from international agencies,

particularly UNICEF, has been pledged for this

program.

The lack of diagnostic services has meant that clinical indications of infection have only rarely

been confirmed by laboratory isolations and

characterizations of infections. While clinical

diagnosis is effective in outbreak situations,

laboratories do have a role to play in detecting

and identifying pathogens, and the powerful

technologies of molecular epidemiology can

make significant contributions to implementing

effective control measures. Capacity building, to

ensure that personnel can detect pathogens in

both clinical and environmental specimens, is an

important component of a good control strategy.

Failure of primary care facilities to provide even simple conditions for case management has

contributed to the high CFR. The provision of

ORS at all primary care clinics would have done

much to reduce the mortality in this epidemic.

Support from international donor agencies to

ensure adequate stocks of ORS should help to

reduce CFR in the immediate future, but long

term commitment by government for financial

support for health services is needed.

Finally, the general economic crisis of Zimbabwe, where unemployment is at 94% and

where there are critical shortages of food and

basic commodities, has contributed to an

increasingly vulnerable population. It is perhaps

difficult to imagine that people do not have

resources to buy salt and sugar, but that is the

reality of Zimbabwe. Most shops now sell goods

only for foreign currency, and the source of such

currency is only through the “black market”

which is beyond the reach of the majority of the

population. Add to this the high cost of transport

to health care centres for those who require

rehydration, and the reasons for the high

mortality in this epidemic can be appreciated.

Now is the time for a recognition of the need for

vigilance in recognizing disease outbreaks at an early

stage, and while we are currently dealing with the

crisis of cholera, there are many other infectious

diseases that are waiting to emerge – anthrax, typhus

and typhoid being only a few. Collaboration between

Zimbabwe and international partners is essential for

effective surveillance and response programs, and

with ongoing changes in the political situation we

have to hope that such international collaborations

can again thrive.

Corresponding Author Prof. P. R. Mason, BRTI, PO Box CY1753

Causeway, Harare, Zimbabwe

[email protected]

Note in proof: The total number of cases of cholera as of 23 March 2009 was 92,432 with 4,072 deaths

(CFR 4.4%). The indications are that control

measures are starting to have an effect, and the

numbers of new cases reported on a daily basis have

been declining.