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CONTENTS EXECUTIVE SUMMARY 3 INTRODUCTION 5 BACKGROUND INFORMATION 7 General Information 7 Kawere Clinic Catchment Area 7 Social Factors 8 Malaria In Relationship To The Area 8 FINDINGS 11 History Of Malaria In The District 11 Possible Past Outbreaks 12 The Present Outbreak 12 Climatic Data 14 Chloroquine Resistance 15 GENERAL COMMENTS AND OBSERVATIONS 16 Malaria Data 16 Blood Slide Examination 17 Analysis Of Blood Slide Results 18 Chloroquine And Village Community Workers 18 Rainfall 19 Control Methods Used During The Outbreak 19 Other Clinics 21 CONCLUSIONS 21 RECOMMENDATIONS 22 REFERENCES 26 PEOPLE CONSULTED 27 ACKNOWLEDGEMENTS 28 INVESTIGATION INTO THE 1994 MALARIA SITUATION OF MUTOKO DISTRICT WITH SPECIAL REFERENCE TO THE KAWERE AREA EXECUTIVE SUMMARY From March to April 1994 a malaria outbreak occurred around Kawere Clinic of Mutoko District in the north eastern part of Zimbabwe. While the outbreak was not very severe in terms of either deaths or cases, it occurred in an area with little known history of malaria transmission, even though the area is traditionally classified as being a seasonal malarial area. This report covers not only the present outbreak at Kawere, but also the environmental, climatological and historical factors of the whole of Mutoko District in an attempt to understand what took place prior to the outbreak. While good data appertaining to malaria in the area was scattered, incomplete and very sparse, the following findings can be surmised from the data available. 1) Mutoko District has had no severe problem with malaria since 1988: the situation prior to 1988 is not known. 2) Mutoko District as a whole recorded the highest number of clinical malaria cases since 1988 in 1992/3 malaria season, but the figures were not considered alarming or problematic. 3) Four clinics, Katsikunya, Nyamazuwa, Kawere and Makosa recorded their highest number of clinical cases in the 1993/4 season differing from the pattern for the rest of the district. Kawere Clinic in particular saw a drastic increase in the number of clinical malaria cases presenting at the clinic. 4) Temperatures in the last decade have risen in the winter months around Mutoko by about one degree centigrade which would facilitate winter survival of both the parasite and vector in the lower parts of the district. In contrast to this, rainfall in the past decade has decreased lowering the possibilities of high malaria transmission: 1992/3 had the highest rainfall since 1989. 5) Blood slide data for the district is completely inadequate. It is almost impossible to make any conclusions about duration of malaria transmission in the district: few slides are taken outside of the peak malaria season of January to May which makes it difficult to surmise whether the vector or parasite is surviving in the district over winter or is being imported each year at the beginning of each malaria season. 6) What exactly happened at Kawere is difficult to determine as blood slide records were not found at the time of the investigation: the area surrounding Kawere Clinic has many environmental factors which would facilitate malaria transmission and it must remain a matter of conjecture at present why malaria only became a problem this year and not in other years. 7) Village Community Workers (VCW) in Mutoko District are issued with chloroquine throughout the year. This makes malaria surveillance more difficult as people may not report to clinics when suffering from malaria. However, Kawere Clinic has not issued chloroquine to VCWs for two years, a period which has seen malaria rise in the area. 8) Another mystery revolves around Hoyuyu One Clinic which reports a fairly large number of slide positive malaria cases. However, the clinic is situated in one of the highest parts of the district i.e an area least likely to have malaria transmission. While the staff at the clinic have considered the area to be malarial due to positive malaria cases appearing every year, the possibility of malaria being caught outside the area and being imported must be considered. Other malaria outbreaks have been reported around in Zimbabwe in 1994 in other marginal areas such as Zaka, Buhera and Mberengwa. The findings of this report are not only relevant to Mutoko, but all other marginal malarial areas of the country. The implications of this report are that malaria transmission may possibly occur in other areas of the country at higher altitudes than previously thought, and that good surveillance and record keeping are necessary so that further outbreaks of the Kawere type do not occur again without warning. The fact that few deaths occurred during Kawere malaria outbreak must be credited to the hard work and dedication of the Mutoko District Health Staff who made every effort within their knowledge and capabilities to contain the situation. The report also reflects social factors in malaria outbreaks and outlines the dangers of the siting of bore holes and wells. The report emphasises the need for other considerations besides simply the availability of water when siting community water points. The winter of 1994 has been particularly severe which may limit vector survival to much lower altitudes than previous years. It will be interesting to note the malaria situation of 1995: recent work carried out in connection with this report suggests that the malarial cases should be less than the previous two years. However, in general, it must be concluded that malaria situation in the district may become worse in the future if recent climatic feature prevails. The reports concludes with a series of recommendations that might be carried out by district health staff of Mutoko District in terms of both surveillance and control so that the malaria patterns of the district might be better understood and lead to improved control (in terms of cost and efficiency) in any future outbreaks. INTRODUCTION Mutoko District of Mashonaland East Province lies in the North Eastern part of Zimbabwe. Most of the district lies between 900 to 1200 metres in altitude in what has been traditionally classified as a seasonal malaria zone. However, records suggest that from at least 1988, most of the district has been extremely marginal in terms of malaria transmission. The situation prior to 1989 is not known due to lack of records except at one clinic (Makosa) which has records going back to 1987: these records suggest that malaria may have been a serious problem in 1988 (Appendix Eleven), suggesting that most of the district is more epidemic in nature than seasonal i.e malaria does not appear on an annual basis, except perhaps in the lower lying areas. Records suggest that for much of the district, malaria was worse in the 1993 than 1994 with the exception of four clinics Katsikunya, Nyamazuwa, Kawere and Makosa which all recorded a general upsurge in malaria in 1994. Of these clinics, Kawere recorded the highest increase in cases. Katsikunya, Nyamazuwa and Kawere all lie on the northern part of the district on the Nyadire River catchment area. Kawere and Makosa are both about 950m in altitude and lie adjacent to Mudzi District (a known malaria area). Both clinics lie next to areas in Mudzi which were not sprayed with insecticide for the first time in many years, though ironically, the adjacent areas in Mudzi did not have much of a malarial problem. This report looks at the malaria situation in Mutoko District as whole but focuses on the Kawere area which had the worst problems. This report also forms part of a research project into malaria outbreaks around Zimbabwe. The research is primarily focused on areas in marginal (epidemic) prone areas of malaria transmission. The project is searching for common denominators between years which malaria transmission does and does not occur so that a predictive model of malaria might be created allowing for malaria outbreaks to be foreseen in advance. The project is looking primarily at climatic, social and water and sanitation factors in outbreak areas, but is continually searching for other factors that might play a part. It is hoped that this research will not only benefit the country as a whole, but each district in which investigations take place. The purpose of this investigation was four fold: 1) Investigate factors that led up to and caused the outbreak. 2) Ascertain if possible if such an outbreak might occur again. 3) In the event of future outbreaks in the area make recommendations about possible control strategies, and 4) While carrying out the investigation, train district staff in malaria surveillance and outbreak investigations so that any mistakes that occurred might be learned and not repeated. The investigation involved collecting data from a variety of sources: Harare for climatological data from the Meteorological Office and blood slide data from Blair Research, Marondera to get an overview of the situation from the perspective of provincial health staff and finally from Mutoko District to collect all relevant data appertaining to the outbreak. In Mutoko District, the complete investigation was carried out in the company of Mr C.Mukandi the Environmental Health Technician of Kawere Clinic. Mr Mukandi had been involved with all aspects of the outbreak and acted as an informant, guide and where necessary as a translator. During this period: 1) Mutoko Hospital, Kawere, Makosa, Nyamazuwa, Hoyuyu One Clinics and Nyadire Mission Hospital were visited and records studied, except in the case of Nyadire Mission where permission was not granted. At all these places a variety of health staff were consulted. 2) Larval surveys were made around Kawere and Makosa Clinics. 3) Two possible focalised outbreak areas of Kawere Clinic (Kugarahanya and Chitiyo) were visited, surveyed and local people questioned. The weakest part of this investigation is that of malarial data from the district, and not as much has been collected as would have been liked. While some more data undoubtably exists, it would require many more days in the district, and at present it seems doubtful that what does exist is likely to make the present situation any clearer. It must be said that in general Mutoko District has not considered malaria to be a particular problem in the past, and consequently has paid little attention to its malaria records which makes past analysis extremely difficult. BACKGROUND INFORMATION General Information Mutoko District lies in the north eastern part of Zimbabwe north of the central watershed (Appendix One). Mutoko District is part of Mashonaland East Province which includes Harare and Marondera the provincial capital (Appendix Two). The western part of Mashonaland East Province lies at high altitude above 1200m and is considered malarial free. At the other extreme lies Mudzi and parts of UMP Districts which lie at low altitudes of below 900m which are established malarial problem areas. In between these two extremes at 900-1200 metres lies most of Mutoko District and parts of UMP, Murehwa and Goromonzi Districts. While altitudes of 900-1200m have been traditionally classified as seasonal malaria areas (Crees & Mhlanga 1985), their exact status is not known in terms of malaria as transmission appears more epidemic in nature: in many years malaria does not appear to be an apparent problem. Kawere Ward, the focal point of the 1994 outbreak in Mutoko District lies at one of the lowest parts of the district (950m) adjacent to Mudzi District (Appendix Three). Administratively, Mutoko District has a population of 126 000 and is divided into 26 Wards (Appendix Four). The outbreak under investigation lies in Kawere, Mbudzi A, Mbudzi B and Musanhi Wards. Much of Mutoko District lies in Natural Region Three, and the area of the 1994 outbreaks in Natural Region Four. Natural Region Three is characterised by annual rainfall of 650-800mm a year and Natural Region Four characterised by rainfall of 450-650mm a year. Rainfall in both areas is characterised by heavy infrequent falls: both areas are considered marginal in terms of crop production. At its lowest altitude, Mutoko District lies at 650 metres in the north east along the Ruenya River which divides Mutoko from Nyanga District in Manicaland. At the other extreme, altitudes of 1400m are found. However, most of the district lies between 900-1200 metres in altitude. Mutoko weather station which lies at 1245m records mean annual temperatures of 20C and rainfall of 700mm (Appendix Five). Temperature extremes range from Mean July temperatures of 15C to Mean November temperatures of 22.6C (Appendix Six). Kawere Clinic at 950m would be expected to record temperatures of about 2C warmer than those recorded at Mutoko assuming an approximate adiabatic lapse rate of 1C for every 150 m in altitude as noted from observations in other parts of the country. While Mutoko town might occasionally experience frost, it is unlikely the area surrounding Kawere does so (Appendix Seven). It is also likely that the rainfall of the Kawere area is less than that recorded at Mutoko. Much of Mutoko District is characterised by huge sparsely vegetated rocky outcrops mainly of granite (black granite is quarried from this area for export). Between the hills often lie potential swampy areas (vleis) which when dry, leave dry stream beds from which many shallow wells are dug. Along these 'valley bottoms' many families grow vegetables to supplement maize production. In general the area around which the outbreak occurred did not appear particularly prosperous, though roads appear well maintained. The whole district is strikingly beautiful in terms of scenery. Kawere Clinic Catchment Area Kawere Clinic lies some 27 kilometres from Mutoko Town. It is four kilometres from the main tar road linking Mutoko with Nyamapanda. Kawere Clinic Catchment Area includes the whole of Kawere Ward (Population 2 800), and five VIDCOs of Mbudzi A (Population 3 298) and five VIDCOs of Mbudzi B (Population 5 184), giving an estimated 8 000 people who use the clinic (Appendix Four). The clinic is also used by some villages of Musanhi Ward which comes under Makosa Clinic due to easier access to Kawere than Makosa. Within these Wards lies 94 villages that use the clinic (Appendix Eight). Many households in this area lie in close proximity to vleis and water (ponds and shallow wells). Most people appear to survive from subsistence farming of maize and the growing of vegetable in gardens close to the shallow wells. While boreholes are fairly common, some are located at a distance from peoples houses and some produce salty water resulting in many people using shallow wells not only for gardens but also for drinking purposes, though it appears that different shallow wells are used for different purposes i.e some for drinking and other for gardens. Along the vleis one can also find natural ponds left by drying up streams and these are mainly used by cattle. There are also two dams in the catchment area, Kaitano Dam and a small dam near the clinic adjacent to Hunda and Chinomona Villages. Much of Kawere and Kugarahanya Villages lie along vleis which contain numerous water bodies. Chitiyo and Nyabote both share a borehole with sweet water: the borehole lies in a vlei with numerous shallow wells. Social Factors It is believed that many of the people in the Kawere Area rarely move far from their homes. Houses, gardens and watering points are all in close proximity to each other, though different households appear to use different wells. Where boreholes are present, people fetch water throughout the day and evening. Boreholes are often distant from peoples homesteads meaning that they either use water locally or move some distance through other households to fetch the water. Due to the numerous rocky outcrops in the area, many footpaths are restricted to valley bottoms i.e through the vleis and in close proximity to ponds and shallow wells: all potential breeding sites for vector mosquitoes. This has significance if water is fetched at night which appears a common occurrence. Malaria In Relationship To The Area The predominant malaria parasite in Zimbabwe is Plasmodium falciparum (Taylor and Mutambu 1986), and the main vector mosquito is Anopheles arabiensis. While A. funestus was believed to have been a major vector, it is believed that it has been almost eradicated due to the intensive house spraying programme conducted in Zimbabwe over the last forty years - A. funestus only feeds indoors (endophilic and endophagic) and is particularly susceptible to residual insecticides (Crees & Mhlanga 1985). A few other vector mosquitoes do exist in Zimbabwe, but their numbers are so low (i.e A. gambiae and A. merus) or are very poor vectors (e.g A. pretoriensis) to be of no major importance. One problem that plagues malaria workers in Africa is that A. arabiensis is a member of a group of mosquitoes known as the A. gambiae complex. In Zimbabwe there are four species belonging to this group known as A. arabiensis, A. gambiae, A. quadriannulatus and A. merus. The problem comes in that all these mosquitoes are identical in looks and can only be distinguished in the laboratory by specialised techniques. The reason this is a problem is the A. quadriannulatus is a none vector of malaria and is the most common of the species, and therefore the presence of the A. gambiae complex is not indicator of malaria transmission. However, for the purposes of investigations, it must be assumed that if malaria transmission is occurring in an area and the A. gambiae complex is present then some of them must be vectors i.e A. arabiensis. Blair Research Institute has stated for many years that perennial areas of malaria lie below 900 metres in the north and 600 metres in the south of the country (Crees & Mhlanga 1985). These altitudes represent the limit of winter mosquito survival as it is believed that low temperatures of 5C and below (Leeson 1931) and frost (De Meillon 1934) kills off A. arabiensis populations. However, from permanent breeding ground in these altitudes, it is believed that A. arabiensis is able to migrate into higher altitudes during the months following winter to areas generally regarded as 1200 metres in the north and 900 metres in the south. The only time this has been recorded is in the Sabi Valley by Crees while working at Blair Research (Personal Communication), but the work has never been published. These altitudes should never be taken literally as temperature conditions vary from year to year and presumably the range in which A. arabiensis is able to over-winter will also vary. Certainly in other parts of Zimbabwe, malaria outbreaks have been recorded up to 1300 metres in altitude (Freeman 1992). Similarly the ability of A. arabiensis to migrate into higher altitudes will vary on account of a number of factors, the most common one being the availability of surface water (i.e much migration is expected to occur along river beds). Therefore early rains, intermittent rainfall and proximity to higher altitudes all determine the extent to which A. arabiensis is able to migrate. For malaria transmission to occur in Mutoko, malaria vector mosquitoes must either survive over winter or migrate into the area. The major question therefore in terms of Mutoko is whether the vector mosquito is able to survive in the Kawere Area over winter: certainly there is no shortage of water if temperatures are favourable for their survival. For malaria to exist in any given area also requires the presence of the parasite. Development of the sporozoites of P. falciparum in vector mosquitoes is also dependent on temperature. It is generally considered that mean daily temperatures of below 18C stops sporozoite development of P.falciparum (Moshkovshy & Rashina 1951). It is also generally accepted that the maximum survival time of gametocytes in blood is about two months (Bruce-Chwatt 1985) and therefore in areas which have temperatures of less than 18C for over two months preclude the possibility of parasite survival even though the mosquito vectors may be present. Even 18C is considered the bare minimum for survival: even at air temperatures of 19 to 20C parasite survival outside of the human body is very difficult (Freeman 1993a). Therefore in areas where mosquitoes manage to survive but have mean daily temperatures of less than 18C for over two months, these areas require that the parasite is imported each year. By definition of Blair Research Institute, most of Mutoko District lies in a seasonal malarial area. Seasonality suggests that malaria appears every year, but records from Mutoko, (while being inconclusive), suggest more epidemic malaria characteristics. However, for practical purposes much of Mutoko District has for many years been considered malaria free and consequently Mutoko District has not been sprayed with residual insecticide since 1990/1 season. For reasons not well understood, these areas have not been as malarial as should be expected: one factors leading to this situation could be reduced rainfall in the district in the last decade (Appendix Five). One factor which is not normally considered that of improved water and sanitation. Even when both the parasite and the mosquitoes are present in any given population, this does not necessarily mean that a large outbreak will occur. For outbreaks to occur, both people and the vector mosquito must come into frequent contact. A. arabiensis feeds at night, and normally does not fly more than half a kilometre from breeding sites. When human activity occurs at night around places of water, increased contact with vector mosquitoes can be expected, and hence increased possibilities for transmission. Boreholes, even with spillage rarely become serious mosquito breeding sites. Rivers and dry river beds used by many rural people for drinking water (where boreholes do not exist) often become vector mosquito breeding sites. In hot areas (usually malarious) water fetching is often done at night increasing contact between man and vector mosquitoes (Freeman 1993d). Gokwe one of the worst malarial areas in Zimbabwe is noticeably lacking in safe drinking water points, whereas Mutoko seemed well endowed. Mosquito Breeding A. arabiensis favours freshly formed sunlit pools for breeding. Its larvae are very susceptible to predators, and when larvae are found, few other animals are living in the same pool. Records from other parts of Africa suggest that they can breed almost anywhere (Gillies & De Meillon 1968). In other parts of Zimbabwe they have been observed in small puddles caused by rainfall, small pools at the edges of larger bodies of water which have become separated from the main body of water goes down, or pools created from cattle hoof prints. Other places observed include "Mifuko" (shallow wells dug in river beds), other pools in river beds, rock pools, drinking troughs, pools with dense weed, roadside pools and shallow wells (Freeman 1992). In other parts of Africa borrow pits (pits formed from making bricks) are a great source of breeding. In fact they will utilise any small or protected pool of water without predators. In ideal conditions A. arabiensis may take as little as one week to breed, but this is temperature dependent so that this period may extend to two months during the colder winter period (Le Sueur 1994). There is no shortage in Kawere Area of potential breeding sites for A. arabiensis. While shallow wells are not ideal breeding sites of A.arabiensis, many shallow wells in Kawere Area were full of weeds affording numerous protected breeding possibilities. FINDINGS History Of Malaria In The District Since 1989 Mutoko District reports up to 10 000 clinical cases of malaria each year (Table One and Appendix Eleven). Peaks of clinical cases are seen most years except for 1992 (the drought year): most of these peaks occur in the expected malaria season of January to May each year. Appendix Eleven shows clinical cases recorded from Kawere, Makosa, Nyamazuwa, Hoyuyu One and Nyadire Mission: in all cases peaks of clinical malaria are seen during the expected malaria season. While most of these clinics lie in the lower part of the district, Hoyuyu One lies at higher altitudes, but as discussed later, these cases may be imported rather than suggesting transmission in the immediate area. TABLE ONE
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