Malaria epidemics in the highlands of Ethiopia.

OBJECTIVE: To confirm the occurrence and describe the patterns of the 2003 malaria epidemics reported in the highlands of Ethiopia. DESIGN: A retrospective descriptive study. SETTINGS: Fifty epidemic affected districts between altitude ranges of 1500 and 2500 m in three regions in Ethiopia. RESULTS: Exaggerated seasonal transmission was observed in 25 districts, 16 in Oromia region and 9 in SNNPR. A sustained upward trend with 3-4 consecutive abnormal seasonal transmissions, which has started since 2002, has been identified in 22 districts. True explosive epidemic malaria was recorded at exceptionally high altitude (around 2500m) in at least one of the health facilities in seven districts. The incidence of malaria in 2003 epidemic has showed a six fold increase on average (range 2-20) from the threshold level. CONCLUSION: Occurrence of a malaria epidemic was confirmed in all studied districts showing that the level of malaria endemicity and magnitude of the problem is increasing. The findings suggest the strategic importance of taking well-timed and appropriately targeted preventive and control interventions.

Deltamethrin-impregnated bednets as an operational tool for malaria control in a hyper-endemic region of Burundi: impact on vector population and malaria morbidity.

Within the framework of the National Malaria Control Programme Burundi, impregnated bednets were promoted through health care facilities, schools and local administration in Nyanza Lac district. The decision to buy a bednet was left to the inhabitants and, as a result, coverage rates between 6 and 65% were observed at sub-district level. Three intervention regions were specified based on the intervention start date. From November 1992 until March 1995, bi-monthly parasitological and entomological surveys were carried out in two areas each of Region 1 and Region 2. After introduction of impregnated bednets in Region 1 the proportions of children under 5 with high parasitaemia were reduced by 42 and 53% in the 2 parasitological survey areas, where the average bednet coverages were 55 and 44% respectively. In the survey areas of Region 2 (control) no significant change occurred during the same period. During the second part of the intervention from September 1994, when intervention was also operational in Region 2, significant decreases in the proportion of high parasitaemia (63 and 42%) among children under 5 years were obtained in both parasitological survey areas of Region 2 (average coverages of 51 and 29%). The positive output of the intervention was maintained and even reinforced in the survey areas of Region 1. Bednets as a tool for malaria control entail specific problems such as coverage, daily use, reimpregnation, and renewal of old and torn nets. Further evaluation has to point out the possible shift of the clinical spectrum and the age-specific admission of malaria cases to assess the long-term benefit of this control method.

[Motivation to acquire and use impregnated mosquito nets in a stable malaria zone in Burundi]. / Motivation à i'acquisition et à i'utilisation des moustiquaires imprégnées dans une zone à paludisme stable au Burundi.

In Burundi, the purchase, acceptance and utilization of impregnated bed nets sold at a promotion price (2 $US) were evaluated in a stable malaria area (South-Imbo, district of Nyanza Lac) where this method of protection was previously unknown to the inhabitants. The sale of the impregnated nets differed between the administrative subdivisions (so-called 'collines') of the area with a coverage varying from 10 to 70% of families. Moreover, in one of these collines with a high overall coverage rate (62%) a difference was also found between the three administrative regions (so-called 'sous-collines') which were socially and economically similar. However, these sous-collines (SC) differed in their geographical location and were found at different altitudes. The real coverage corresponding with the percentage of families showing at least one installed bed net, was calculated for each SC. This coverage was 77% in the SC-1 situated in the low wet area and decreased gradually to 14% in the SC-3 at the highest altitude. The purchase of a bed net does not necessarily mean that people will use them. About 30% of the bed nets bought at the promotion price could not be found and most of them were resold in the neighbouring country (Tanzania). Between 7 (SC-I) and 47% (SC-3) of the bed nets were still packed and not in use. The motivation for buying and using impregnated nets appears to depend essentially on the nuisance level caused by mosquitoes, as shown by the abundance of the mosquitoes in the SC-1 situated in the low wet area (75 bites/man/night) compared to that observed in the SC-2 located at a higher altitude (i bite/man/night). The authors conclude that appropriate health education and information should be developed and promoted by health staff, local authorities and teachers in order not only to improve comfort by decreasing the insect nuisance, but also to decrease the considerable malaria burden in the community.

Using community health workers for malaria control: experience in Zaire.

The potential for using community health workers (CHW) for administering timely and effective treatment for presumptive malaria attacks was evaluated in the Katana health zone in Zaire. In each of the 12 villages of an intervention area (area A) with 13000 inhabitants, a CHW was trained in the use of a simple fever management algorithm. The CHWs performed their services under the supervision of the nurse in charge of the area's health centre (HC). Malaria morbidity and mortality trends were monitored during 2 years in area A and in an ecologically comparable control area (area B), where malaria treatment continued to be available at the HC only. Health care behaviour changed dramatically in the intervention area, and by the end of the observation period 65% of malaria episodes were treated at the community level. Malaria morbidity declined 50% in area A but remained stable in the control area. Parasitological indices showed similar trends. Malaria-specific mortality rates remained, however, at essentially the same levels in both areas. The non-comprehensiveness of the CHWs' care and their ambiguous position in the health care system created problems that compromise the sustainability of the intervention.

PIP: Along the western shore of Lake Kivu in eastern Zaire, Katana health zone's primary health care (PHC) development plan established a pilot community trial in 1987 in 12 villages. It concerned community health workers (CHW) who provide chloroquine phosphate (25 mg/kg) treatment over 3 days for episodes of fever (i.e., presumed malaria attacks). A socioeconomically comparable area about 30 km south of the intervention area with the same malarial ecology and malariometric indices served as the control area. Malaria treatment continued to be offered at the health center only in the control area. Both areas were peninsulas. Villagers selected a literate volunteer to serve as the malaria CHW. CHWs received 2 weeks of in-service training in the area's health center. They charged no consultation fees. Malaria prevalence and incidence fell 50% in the intervention area, a significant decline. The crude parasitological index and high parasitemia index declined by 5- and 6-fold, respectively, in the intervention area compared to 2-fold in the control area. Even though mortality rates fluctuated in both areas, they remained essentially the same in both areas. The population in the intervention area had adopted important health care behavior. For example, the number of malaria episodes that remained untreated decreased 7%, while it increased 8% in the control area. In the intervention area, the number of cases treated at home and by the CHW increased 16% and use of the informal private sector fell markedly (-23%). Thus, more than 65% of malaria episodes were treated at the community level. There were problems revolving around the non-comprehensiveness of CHWs' care and their unclear position in the health care system. The major problems concerned the lack of a long-term commitment to CHWs on the part of the health care system and the failure to achieve real community participation. Even though malaria morbidity and parasitological indices were reduced and health care behavior improved, the problems compromised the sustainability of the intervention.

An etiologic study of hemoglobinuria and blackwater fever in the Kivu Mountains, Zaire.

Between January 1985 and March 1986, in the high altitude area of Kivu, Eastern Zaïre, 38 patients presenting with hemoglobinuria as main manifestation were investigated. Profound glucose-6-phosphate dehydrogenase deficiency was detected in 4 patients, leptospirosis in 2 and Hantaan virus infection in 2. Hemolysis was doubtful (haptoglobin > 40 mg/dl, Hemoglobin > 12 g/dl) in 2 patients. Other potential causes of hemoglobinuria such as hemoglobinopathy, toxic agents, infectious diseases or blood transfusion incompatibility were carefully screened and excluded. The syndrome observed in the remaining 28 cases was strongly suggestive of blackwater fever (BWF) as described in malaria patients by several authors under the french name "fièvre bilieuse hémoglobinurique". Quinine was used as curative treatment of malaria before admission in a significant greater proportion (p < 0.01) of patients with BWF compared to patients with uncomplicated malaria, suggesting that this drug might have played a triggering role in the genesis of BWF. However, quinine was usually administered at inadequate doses to malaria patients non responding to chloroquine and belonging to a population of whom 50% are non immune. It may thus also be hypothesized that BWF in our patients could result from a hyperparasitemic state that remained undetected because of an unusual synchronous lysis of infected erythrocytes. In the latter case BWF would correspond to a major complication of falciparum malaria only coincidentally related to the use of quinine.

A hundred per cent of fields positive in a thick film: a useful indicator of relative changes in morbidity in areas with seasonal malaria.

The classical method of estimating the density of Plasmodium falciparum in blood, by counting the number of trophozoites per leucocyte, is compared with a method in which the proportion of microscope fields in a thick film that include at least one asexual form is evaluated. Mean densities of 144 and 1920 trophozoites/microliters blood gave 9.5% and 99.5% positive fields, respectively, and < 5% of slides with 100% positive fields were of blood with < 2000 trophozoites/microliters. The proportion with high parasitaemia (PHP) in a population, defined as the proportion of individuals with 100% positive fields, is proposed as a simple and reliable indicator of relative changes in malaria morbidity due to seasonal fluctuations or control activities. However, the use of this index is limited to areas with intermediate malaria stability. Data from a longitudinal survey in Burundi, presented to illustrate the use of PHP, show that PHP undergoes important fluctuations related to transmission. In contrast to the parasite index, the amplitude of fluctuations in PHP decreases with age as a result of acquired protective immunity. Although two health centres, one in a vector control area and one in an area with no control, reported similar proportions of cases of clinical malaria among their patients, PHP was about three times lower in patients from the vector control area. The estimation of the efficacy of a malaria control programme from simple clinical information appears unreliable. Sentinel health centres, each equipped with a microscope to estimate PHP, may often be better indicators of changes in morbidity.

[Risk approach in the diagnosis of malaria in high altitude regions]. / L'approche de risque dans le diagnostic du paludisme-maladie en régions d'altitude.

Sixteen cases of malaria are reported per thousand inhabitants per year in Kayanza, a province in the High Plateaux of Burundi. A case control study was conducted between October 1990 and March 1991 to better document this phenomenon. The majority of confirmed cases presented in persons who had recently sojourned in an endemic area (relative risk = 18). All except one of the other patients were carriers of plasmodium species that can cause late recurrences, which is compatible with the absence of local transmission. The presumptive diagnosis of malaria, as it is routinely made in the health centres, is not very specific (60%) and it has a positive predictive value of only 10%. This implies that an anti-malaria treatment is useless for 90% of the patients who receive it. It also means that the true malaria incidence rate in Kayanza can be estimated at less than 1 per thousand per year. We propose an alternative diagnostic strategy based on the risk differences between population sub-groups. It should permit an adequate patient management and a satisfactory surveillance of malaria in non-endemic epidemiological strata.

[Development of a simple and reliable method for estimating malaria morbidity according to the modified Muench model]. / Développement d'une méthode simple et fiable pour estimer la morbidité palustre à partir du modèle de Muench modifié.

To evaluate malaria control measures one needs to document morbidity trends over time. Malaria morbidity incidence rates (MMIR) can be estimated from multi-round surveys that use specially designed questionnaires, but they are cumbersome and very expensive. Parasitological incidence rates (PIR), in contrast, can be estimated from malariometric indices, which are simple to collect, but are difficult to interpret in terms of morbidity. We present an extension of Muench's mathematical model which overcomes this drawback. Between June 1990 and May 1991, data were collected in Nyanza-lac, South Burundi, in two parallel studies of children under 6 years old. A fortnightly morbidity recall survey documented MMIR by age. Thick blood films were collected bimonthly to calculate PIR according to Muench's model. The proportion of high parasitaemia (PHP) was defined as the number of slides with 100% of the examined microscopic fields positive for at least one asexual form of Plasmodium falciparum over the total number of slides examined. To test the hypothesis that parasitological data can provide an accurate approximation of malaria morbidity, age specific PIR were multiplied by the corresponding PHP to obtain the incidence rate of high parasitaemia (HPIR). Close agreement was found between MMIR and HPIR (regression coefficient = 1.15; r2 = 98%). Thus, this method offers a simple, accurate and cost-efficient alternative for questionnaire-based morbidity surveys.

[Mortality and morbidity at young ages in a stable hyperendemic malaria region, community Nyanza-Lac, Imbo South, Burundi]. / Mortalité et morbidité aux jeunes âges dans une région à paludisme hyperendémique stable, commune de Nyanza-Lac, Imbo sud, Burundi.

A malaria control programme based on the extensive use of impregnated bednets is planned in an stable hyperendemic malaria area in Burundi (Nyanza-Lac district) where the average number of infective bites per person per year was 312 during the preintervention period. In order to be able to evaluate in depth this important intervention, vital events such as mortality and morbidity were studied in under five-year-old-children during a full year period between June 1990 and May 1991 before the intervention. Village reporters have visited every three weeks 1,200 randomly selected households and completed specific mortality and morbidity questionnaires (prevalence and incidence with a 7 day recall period) adapted from "MRC" questionnaires in the Gambia. Infant and child mortality rates were respectively 108 and 24/1000/y. The definition of a malaria death was based on the opinion of 2 physicians (by consensus) and on the following symptoms alone or in combination: fever < 8 days, convulsions or unconsciousness in the absence of symptoms suggesting an alternative diagnosis. According to this previous definition, malaria was responsible for more than 30% of mortality in under five-year-old-children (specific mortality rate 0-4 year: 14.4/1000/y; specific rate 0-1 year: 38/1000/y; specific rate 1-4 year: 8/1000/y). Diarrhoea (8.1/1000/y) and respiratory tract infections (6.0/1000/y) were respectively the second and third major causes of death. Malaria was also the first cause of morbidity with a yearly average incidence rate of 1.17/person in children under 5 years. Malaria morbidity incidence was highest in children aged 1-2 years (1.79 malaria episodes/person/y).(ABSTRACT TRUNCATED AT 250 WORDS)

Demographic findings relevant for health care planning and evaluation collected through a malaria control project in the Kivu Mountains, Zaire.

Population studies were conducted in the margin of a community based malaria control programme in the Katana Health zone, in the Eastern part of Zaire. The reported findings are based on prospective registration of vital events from March 1986 through February 1987. At mid term 28.083 people were covered. The age and sex structure of the population was typical for tropical Africa, apart from an excess of males to females after the age of 64. The mean age at marriage was 21.2 years for women and 25.6 years for men. 89% of women did not complete a single year of formal education. The crude fertility rate was 250/1000 and total fertility 8.3 children. The infant mortality rate and the child mortality quotients attained 130/1000 and 183/1000 respectively. The crude death rate was 23 per 1000 and the natural population growth rate 31/1000. Due to a net out-migration of 28/1000 the zone's population remained, however, virtually stable. The latter observation questions the purported role of demographic pressure as a key determinant of the region's slow socio-economic development. The other findings provide valuable baseline and background information for planning and evaluating health-related activities.

PIP: High population growth rates have been considered a major problem in the Kivu region of Zaire and a key issue for the future development of the rural areas situated near Kivu lake. Overpopulation and the resulting land shortage were held responsible for the disastrous nutritional situation and the population explosion was said to limit the impact of health care activities. A paucity of recent demographic data for the region, however, has made it difficult to assess whether these claims are valid. The authors report findings from population studies conducted in the margin of a community-based malaria control program in the Katana Health zone in the eastern part of Zaire. Findings are based upon the prospective registration of vital events from March 1986 through February 1987. 5497 households were counted and 28,083 people were covered at midterm. 19.9% of the population was younger than 5 years old, 47.3% under age 15, and 3.7% above age 64. Women aged 15-49 comprised 21.5% of the total population. The mean age at marriage was 21.2 years for women and 25.6 for men, with more than 40% of the elder men having more than one wife. 89% of the women had not completed one year of formal education. The crude fertility rate was 250% with total fertility at 8.3 children per woman. The rate of infant mortality was 130%, the child mortality quotient was 183%, the crude death rate was 23 per 1000, and the rate of natural population growth was 31%. The net out-migration rate of 28% toward less populated rural or urban areas, however, kept the zone's population size almost stable. Increasing demographic pressure can therefore probably not be held responsible for the region's economic stagnation. Dependence upon customary authorities, the land tenure system, and the quasi-feudal organization of agricultural production and crop commercialization seem to offer more plausible explanations.

[Campaign against malaria vectors in the framework of a rural development project in Burundi]. / La lutte contre les vecteurs du paludisme dans le cadre d'un projet de developpement rural au Burundi.

In the context of a large project for the socio-economic improvement of the Imbo area, measures were taken for the integration at all levels of malaria control: health centres for improvement of curative care; hygiene and sanitation centres, communes and agricultural projects for vector control; craftsmen, cooperatives and social centres for the manufacture and selling of impregnated bed-nets. The adopted strategy for malaria control results from preliminary epidemiological studies. The recommended measures are the improvement of medical care and vector control. The latter is based on indoor spraying of malathion, once a year. Malathion is only active during the period (2 months) of highest transmission, which occurs at the end of the rainy season. Occasionally other insecticides are used. Impregnated bed-nets with deltamethrin and village draining are complementary methods. In villages of the rice-growing area with good participation of the community, vector control activities have a considerable impact on malaria prevalence. About 70% before the intervention, the prevalence does not exceed 10% in 1990. High parasitaemia (greater than 2000 troph./microliters), and hence morbidity, decreased considerably (35% in 1983 to less than 5% in 1990). In villages with poor community participation, the decrease of prevalence is less spectacular (from 70% to 25%). Drains are not kept in repair and constitute new breeding places of vectors in the populated areas. The use of mosquito bed-nets is not common, a better information campaign should overcome this unpopularity. In peri-urban villages, inhabitants are complaining about indoor spraying, but the results are satisfactory. This programme demonstrates that reducing malaria prevalence and morbidity with conventional measures is feasible in particular biotopes. Health education activities in the Imbo Centre must be pursued and adapted according to the professional activities of the community.

[Malaria index according to age and seasons in the health region of Katana, in mountainous Kivu, Zaire]. / Indices paludométriques selon l'âge et selon les saisons dans la zone de santé de Katana, au Kivu montagneux, Zaïre.

A longitudinal malaria survey was undertaken in children under five in 5 villages of Katana Rural Health Zone in Kivu, East Zaire. During the year 1983, seasonal fluctuations ranging from 25 to 44% were observed in the parasitological index as well as concomitant variations from 5 to 18% in the splenic index. More malaria transmission seems to occur during the long dry season (June to September). In order to prepare an operational research project to be conducted in two geographically delimited areas of the Health Zone, a complementary survey was organised in February 1985. This survey yielded details on parasitological, splenic and serological index in relation to age. These malaria indices were similar in the two areas and all gradually increased with age to reach maxima of respectively 42%, 13% and 55%. The Katana region, situated at an altitude of 1500 meters, on the shores of lake Kivu, is apparently characterized by an unstable and meso-endemic malaria. The applicability and feasibility of some alternative malaria control strategies are discussed.

[Study of general mortality and of mortality related to malaria in the mountains of Kivu, Zaire]. / Etude de la mortalité globale et de la mortalité liée au paludisme dans le Kivu montagneux, Zaïre.

A longitudinal study in the "health region" of Katana (Kivu, Zaïre) has permitted to determine age and disease specific mortality rates. The infant mortality rate is 172 per 1000/year, the child mortality rate 45 p.1000/year and the crude rate 24 p.1000/year. Two thirds of this mortality are related to infectious and parasitic diseases: measles, diarrhoea, respiratory diseases and malaria. In the mountainous Katana region (4500 feet), malaria is responsible for 12%, of the decrease and the specific mortality rates are 3 p.1000/year in the general population and 18 and 6 p.1000/year in, respectively, the 0 to 11 month and 1 to 4 year age groups. We discuss the potential of PHC to improve, in the framework of an integrated development approach, this unfavorable health situation.