During the cholera epidemic in South Africa, 1980-1987, 25251 cases of cholera were bacteriologically proven. The case-fatality rate was 1,4%. Outbreaks occurred in the summer rainfall season. Age-specific aUack rates followed the pattern typically found during the 'epidemic phase' of the disease in most years. The vast majority of patients were black South Africans living in rural areas with an average annual rainfall in excess of 600 mm. The containment strategy employed is summarised. Despite the apparent eradication of the disease, it is strongly recommended that vigilance should be maintained and investigations of all possible sources of infection and all human contacts of any new proven case should be carried out speedily and thoroughly

du Plessis, G.

Kustner, H. G. V.

English

AJOL - African Journals Online

SAMJ VOL 79 4 MAY 1991 539The cholera epidemic in South Africa, 1980 - 1987Epidemiological featuresH. G. V. KUSTNER, G. DU PLESSISSummary Clinical featuresDuring the cholera epidemic in South Africa, 1980-1987,25251 cases of cholera were bacteriologically proven. Thecase-fatality rate was 1,4%. Outbreaks occurred in the summerrainfall season. Age-specific aUack rates followed the patterntypically found during the 'epidemic phase' of the disease inmost years. The vast majority of patients were black SouthAfricans living in rural areas with an average annual rainfall inexcess of 600 mm. The containment strategy employed issummarised.Despite the apparent eradication of the disease, it isstrongly recommended that vigilance should be maintainedand investigations of all possible sources of infection and allhuman contacts of any new proven case should be carriedout speedily and thoroughly.S AI, Med J 1991; 79: 539-544.The dynamic spread of the seventh pandemic of cholera canconveniently be subdivided into three geochronological periods.The first stage involved the invasion of all the states·of South-East Asia, the second the invasion of the states of mainlandAsia and the third stage the Middle East-Afro-Europeaninvasion. 1 Cholera in South Africa was clearly part of the thirdperiod. As early as 1971 South Africa was considered to be atrisk. Hot, humid summers, sea-ports, overcrowded communitieswith a low standard of environmental sanitation and scanty,restricted and unprotected water supplies in certain areasfacilitated the introduction of cholera into South Africa.2A Cholera Surveillance Programme for the mining industrywas started in November 1973. During March 1974, twoeastern Transvaal coalmines and 1 goldmine yielded cholera-positive sewer pads, and on 25 March 1974 the sewer of awestern Transvaal goldmine also became positive. Two healthycholera carriers were found on this mine during a rectal swabsurvey. The epidemic was contained by the administration ofoxytetracycline and mass vaccination of all mineworkers. 3 In1978, 3 confirmed cases of cholera in South African touristswere notified, none of whom had acquired the disease locally.4The first case of cholera in South Africa in an open com-munity, was diagnosed on 2 October 1980 at Shongwe Hospitalin KaNgwane. An epidemiological· investigation was launchedon 8 October 1980. The one common factor found among allpatients was that they lived on farms at Malelane and haddrunk water from the Crocodile-Malelane irrigation canal.5Department of National Health and Population Develop-ment, PretoriaH. G. V. KUSTNER, B.SC.,M.B.B.CH.,M.D.National Epidemiological Service, South African MedicalService, South African Defence Force, PretoriaG. DU PLESSIS, M.B. CH.B.Reprint requests to: The Director: Epidemiology, Dept of National Health and PopulationDevelopment, Private Bag X828, Pretoria, 0001 RSA.Accepted 20 De<: 1990.This cholera pandemic was caused by Vibrio cholerae El TorInaba serotype. El Tor is a hardier organism and survives forlonger periods in the environment than the classic form; it isalso excreted for longer periods in stools after infection and75% of cases are asymptomatic. 1 Persons infected with thisorganism remain mobile and may spread the disease, sheddingmillions of vibrios in their stool for about 2 weeks.In severe cases cholera causes profuse diarrhoea of suddenonset, which is explosive in character. It also causes typicalrice-water stools and severe dehydration ensues. The stools areodourless, except for a mildly fishy smell. Effortless andprojectile vomiting is common and dehydration is marked inpatients with both diarrhoea and vomiting. A South Africanpatient was shown to have lost 25 litres of fluid in 24 hours perrectum. Such profound dehydration is frequently accompaniedby subnormal temperatures. In a Natal study6 it was foundthat the majority of patients admitted to hospital were severelydehydrated and shocked, with 72% presenting with systolicblood pressures below 100 mmHg; blood pressures wereunrecordable in 10% of patients. The severe electrolyteimbalance following such a dramatic derangement of the normalgastro-intestinal metabolism is the cause of the severe legmuscle and abdominal cramps often encountered in untreatedpatients.EpidemiologyBeing part of the seventh pandemic, the entire recordedpresence of cholera in the general South African communitywill, in this article, be referred to as the 'cholera epidemic'.The individual phases, on the other hand, will be referred toas 'epidemic periods'.The surveillance of cholera in South Africa was based onbacteriologically proven specimens of V. cholerae El Tor; inall, 25251 positive cases were identified, all of the Inabaserotype.Seven cholera epidemic periods, designated Cholera I - VII,occurred in South Africa between October 1980 and July1987. The duration, extent and case-fatality rate of the variousperiods are summarised in Table I.TimeThe individual outbreaks by month of occurrence are illu-strated in Fig. 1 and Table 11.Cholera has a seasonal pattern that appears to follow theambient local patterns of rainfall and temperature (Fig. 2).7PlaceThe initial cases were all from KaNgwane and the Malelanearea in the eastern Transvaal, in close proximity to the Mozam-bique border, whence spread extended upstream along thecourses of the Crocodile and Kaap Rivers and then furtherafield (Fig. 3).4 More than 99% of all cholera patients fell ill in540 SAMJ VOL 79 4 MEI1991o·TABLE I. NO. OF CASES AND DEATHS FROM CHOLERA IN SOUTH AFRICA, 1980 - 1987Duration No. of cases No. of deaths Case-fatalityratio (%)Cholera I Oct 1980 - Jul 1981 3786 42 1,1Cholera 11 Aug 1981 - Jul 1982 11 141 218 2,0Cholera III Aug 1982 - Jul 1983 7638 62 0,8Cholera IV Aug 1983 - Jul 1984 1977 20 1,0Cholera V Aug 1984 - Jul 1985 568 4 0,7Cholera VI Aug 1985 - Jul 1986 134 2 1,5Cholera VII Aug 1986 - Jul 1987 7 0 0--- --Total 25251 348 1,41TABLE 11. BACTERIOLOGICALLY PROVEN CASES OF CHOLERA IN SOUTH AFRICA BY MONTH, 1980 - 1988Cholera epidemic periodI 11 III IV V VI VII VIIIMo. 1980/81 1981/82 1982/83 1983/84 1984/85 1985/86 1986/87 1987/88Aug 1 101 62 7 12 4 0Sep 0 92 64 1 7 0 0Oct 259 19 220 189 6 0 0 0Nov 334 476 442 199 1 0 3 0Dec 360 913 488 303 7 2 0 0Jan 1 180 2540 1232 345 30 47 0 0Feb 572 2826 1684 155 102 52 0 0Mar 268 1450 1263 169 53 11 0 0Apr 575 1407 844 178 124 2 0 0May 202 902 844 182 175 1 0 0Jun 33 486 300 99 39 0 0 0Jul 3 121 128 32 23 0 0 0-- -- -- -- -- - - -Total 3786 11 141 7638 1977 568 134 7 0Fig. 1. Bacteriologically proven cases 0; cholera per month,Cholera I - VII.Numberofcases300025002000150010005001981 1982 1983Year1984 1985 1986Tempe- cholerarature railfall casesIt) (mm)28 14021 105200014 70 1500355001983 1984Fig. 2. Average minimum temperature, average rairifall andnumber of bacteriologically proven cases of cholera by month,August 1980 - July 1984 (..... = average rainfall; - - - - - =minimum temperature; = cholera cases).areas with an annual rainfall of more than 600 mm (Fig. 4).8No major outbreaks were reported from areas of similar socio-economic status in dry arid regions of the country.The last 3 bacteriologically proven cases of cholera werereported in November 1986 from Eshowe and Greytown inNatal.SubjectsThe age-specific anack rate was found to increase withadvancing age (Table Ill; Fig. 5).4 During Cholera I, 1I andIII the anack rate for female subjects was higher than for malesubjects, while for Cholera IV, V and VI the anack rates werealmost the same for both sexes. The age-specific anack rates,CHOLERA III31/7/82-29/7/83•CHOLERA VII1[8/86- 31/7/87SAMJ VOL 79 4 MAY 1991 541CHOLERA IV30/7/83- 29/7/84Fig. 3. Geographical distribution of cholera cases - Cholera I - VII.542 SAMJ VOL 79 4 MEI1991TABLE Ill. AGE- AND SEX-SPECIFIC ATTACK RATES, BASED ON BACTERIOLOGICALLY PROVENCASESl100 000 POPULATION AT RISK DURING CHOLERA I-VI, 1980-1986Cholera epidemic periodAge group Sex 11 III IV V VI(yrs)0-9 M 39 58 39 51 15 4F 38 54 31 46 12 410 - 19 M 29 61 31 19 8 2F 44 63 29 13 9 320 - 29 M 38 55 32 23 8 8F 63 102 44 30 20 1430 - 39 M 58 80 45 29 23 11F 79 122 62 34 12 1340 - 49 M 79 117 55 46 30 16F 85 144 63 30 21 250 - 59 M 100 113 51 48 38 13F 114 142 74 42 25 760 - 69 M 187 195 88 40 7 7F 200 224 145 73 57 1670+ M 117 161 99 59 107 11F 89 181 97 35 51 0Overall M 56 83 41 35 17 7F 69 102 47 33 17 7........................CHOLERA IVCHOLERA 11.•......CHOLERA IIICHOLERA Io+---,--...--r---,---,--r--,50250150100250200Rate200Fig. 4. Geographical distribution of cholera cases in relation toareas of highest rainfall, 30 September 1980 - 31 July 1987.CHOLERA VI0- 10- 20- 30- 40- 50- 60- ro.AgeCHOLERA V.........O+---,-.......:r--r-.....-,...--r--,0- 10- 20- 30- 40- 50- 60- 70+Age50250150200100comparing Cholera I with Cholera 11, increased in all agegroups. Of the 1977 patients diagnosed during Cholera IV,1968 were black, 6 Asian, 2 coloured and 1 white.8 During theother epidemic periods, the overwhelming majority of patientswere also black.Cholera is a disease of poor sanitation and poor livingconditions and, in South Africa, was most prevalent in fairlydensely populated rural communities of low socio-economicstatus.Mode of transmissionDuring Cholera III a matched-pair case-eontrol study wassuccessfully conducted in the village of Moletlane. It wasFig. 5. Age- and sex-specific attack rates, based on bacterio-logically proven cases/100000 population at-risk - Cholera I -VIc- ----= male subjects; = female subjects).shown that consumption of open river water was positivelyassociated with an increased risk of contracting the disease.9Anecdotal repons suggested that shared food brought intominers' quaners after a week's leave in a cholera-infected ruralarea was accompanied by an increased risk of food-borneinfection. A similar impression was formed after an investi-gation on a Natal mission reserve. 10EnvironrnnentalsurveUUanceThroughout the epidemic, open water courses and sewageeffluents were regularly and repeatedly tested for the presenceof pathogenic V. cholerae and often found to be positive. Inthe eastern Transvaal spread along water courses was distinctly'retrograde. I IEvery so often cholera struck urban communities. Suchoutbreaks were always very limited in extent, pointing, inceralia, to the protective effect of safe and lavish water supplies.Control measuresIn response to the introduction of cholera to the RSA, thethen Depanment of Health, Welfare and Pensions devised andimplemented a cholera containment strategy, which embodiedthe following'principles, several of which are quoted verbatim. 12Cholera surveUUance'An attempt must be made at bacteriological diagnosis in allcases of gastro-enteritis presenting at hospitals and clinics. Itis essential to educate all health workers regarding cholera andto create an awareness of possible cholera cases ....'All health workers must be equipped with a cholera packcontaining: (1) screw-top specimen bottles containing alkalinepeptone water; (il) sterile rectal swabs; (iil) disposable gloves;(iv) wooden spatulae for collecting faecal material; (v) labora-tory request forms; (Vl) instruction for collection and dispatchof specimens ... .'Oral rehydration'Oral rehydration of patients with diarrhoea . . . will curemany cases and save many lives .... In the case of cholera allbut the most severe cases can be successfully treated in thisway ... .'Mineral substitutes, electrolyte solutions and ion exchangepreparations were used for oral rehydration.Foodhandlers'All foodhandlers in the potential cholera areas must besubjected to gastro-intestinal surveillance . . . .' This wasfollowed by the specific instructions.ContactsContacts were defined as members of the household of aninfected person. They were given tetracycline 1 g immediatelyand 250 mg 6-hourly for 4 doses. Contacts were confmed totheir homes until the course of tetracycline had been completed.Health education was provided on a wide front with specialemphasis on personal and food hygiene and the provision ofspecific instructions regarding the preparation and use of safewater. Ensuring the safety of the available water suppliesSAMJ VOL 79 4 MAY 1991 543involved protection of the water source, boiling water and theuse of chlorine - even household bleaches.Gene:&:al'... Disinfect houses, drains and surroundings with bleachingpowder.'Proper disposal of stools and vomitus.'Bum refuse and garbage.'Wash soiled clothes after soaking in cresol solution.'Chlorinate domestic water ... .'Unsolved problemsTo date certain problems remain unsolved:1. How does V. cholerae survive during the inter-epidemicperiods? The maximum incubation period for V. cholerae is 5days. It is on record that 18 incubation periods, with no casesbeing reponed during October and November 1985, and only2 in December, were suddenly followed by an upsurge in theoccurrence of the disease (Fig. I: Table Ill). Three theorieshave been proposed to explain this: (I) persistence of long-term or typhoid-like carriers; (il) persistence of the organismin a free-living, altered or adapted form, capable of revertingto a pathogenic variety; and (iil) continuous year-round trans-mission by subclinical 'cases. I At present it is accepted that (iil)best explains the continuation of the disease.2. Primary health care in the prevention of the disease: incenain deep rural areas the accessibility and outreach ofprimary care services is wanting, so that timeous interventionwas difficult. This matter is receiving continuous attention andprogress is cenainly being made, albeit at a pace that couldand should be increased.ConclusionsThe communities most severely affected were blacks in ruralor deep rural, relatively high rainfall areas, such as in atal,KwaZulu and KaNgwane. A detailed' analysis of cases inUmzinto showed that at district level an epidemic would passthrough a community, with cases occurring no funher apanthan the accepted maximum incubation period of 5 days.13Most probably, what was seen was a spread from one virginlocal community to the next, i.e. a continuous sequence oflocalised epidemics rather than real endemicity. This is largelyborne out by the age-specific attack rates per epidemic period,of which there were 7.One might perhaps be initially inclined to amibute the fallin incidence and the ultimate subsidence of cholera to thecontrol measures instituted. While it is true that field staff didexcellent work and often had to improvise, panicularly at the::height of the epidemic, it is probable that the disappearance ofthe disease was also effected by those unknown factors listed. above, which continue to baffle scientists.The single most imponant challenge, epidemiologically andotherwise, is to solve the riddle of the organism's survivalduring non-epidemic periods. The fITst cases diagnosed in anynew outbreak are the primary source of information and mustbe vigorously investigated. In the meantime it is good counselto be wary of cholera and to maintain low-level, on-goingsurveillance in those areas that bore the brunt of the disease.The recent reappearance of appreciable numbers of cholerapatients in neighbouring Mozambique, with 126 reponedcases and 14 deaths from 28 April to 4 May 1990 and 374cases and 8 deaths from 5 - 12 May 1990,14 merely serves tounderscore the urgent need to increase our awareness andvigilance.544 SAMJ VOL 79 4 MEI1991We should like to thank the field staff on whose diligentreponing this entire study is based; the laboratories for submittingall the reports; Professor Margaretha Isaacson for her manyinvaluable and sustained contributions to the investigation andcontainment of cholera, and Mariene Muller for her meticulousmaintenance of the cholera database. The Director-General of theDepartment of National Health and Population Development isthanked for permission to publish.REFERE CESI. Barua D, Burrows W. Cholera. Philadelphia; WB Saunqers, 1974: 2, 384,388,391.2. Editorial. Cholera. S AIr Med] 1971; 45: I.3. Isaiicson M, Clarke KR, Ellacombe GH et al. The recent cholera outbreakin South African gold mining industry: a preliminary report. S AIr Med J1974; 48: 2557-2560.4. Department of Health, Welfare and Pensions. Cholera in the TransvaalLowveld. Epidemiological Comments 1980; 7: Oct.5. Kiisrner HGV, Gibson IHN, Carmichael TR et al. The spread of cholera inSouth Africa. S Afr Med] 1981; 60: 87-90.6. Seedat MA. Cholera in South Africa. Modern Med 1982; 7: 81-88.7. Department of Health, Welfare and Pensions. Analysis of second choleraepidemic, South Africa 1981/82. Epidemiological Comments 1982; 9: Aug.8. Department of Health and Welfare. Analysis of Cholera IV. EpidemiologicalComments 1984; 11: Oct.9. Sinclair GS, Mphahlele M, Duvenhage H, Nichols R, Whitehom A,Kiisrner HGV. Determination of the mode of transmission of cholera inLebowa. S AIr MedJ 1982; 62: 753-755.10. Sitas F. Some observations on a cholera outbreak at the Umvoti MissionReserve, Natal. S Afr MedJ 1986; 70: 215-218.11. Department of Health, We.lfare and Pensions. Further notes on the 1980-outbreak of cholera in South Africa. Epidemiological Comments 1980; 7: Nov.12. Department of Health, Circular: Cholera surveillance (ref. 1012'{1/912),August 1979.13. Department of Health and Welfare. Analysis of Cholera Ill. EpidemiologicalComments 1983; 10: Oct.14. World Health Organisation. Diseases subject to the regulations: notificationsreceived 11 - 17 May 1990. Wkly Epidemiol Rec 1990; 65: 149-156.

The cholera epidemic in South Africa, 1980 - 1987 Epidemiological features

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The cholera epidemic in South Africa, 1980 - 1987 Epidemiological features

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