Rapid Urban Malaria Appraisal (RUMA) III: epidemiology of urban malaria in the municipality of Yopougon (Abidjan)

Smith, Cissé Guéladio, Tanner Marcel, Wang Shr-Jie, Lengeler Christian, Vounatsou Penelope, Tanner

Description

Currently, there is a significant lack of knowledge concerning urban malaria patterns in general and in Abidjan in particular. The prevalence of malaria, its distribution in the city and the fractions of fevers attributable to malaria in the health facilities have not been previously investigated. Methods A health facility-based survey and health care system evaluation was carried out in a peripheral municipality of Abidjan (Yopougon) during the rainy season of 2002, applying a standardized Rapid Urban Malaria Appraisal (RUMA) methodology. Results According to national statistics, approximately 240,000 malaria cases (both clinical cases and laboratory confirmed cases) were reported by health facilities in the whole of Abidjan in 2001. They accounted for 40% of all consultations. In the health facilities of the Yopougon municipality, the malaria infection rates in fever cases for different age groups were 22.1% (under one year-olds), 42.8% (one to five years-olds), 42.0% (> five to 15 years-olds) and 26.8% (over 15 years-olds), while those in the control group were 13.0%. 26.7%, 21.8% and 14.6%, respectively. The fractions of malaria-attributable fever were 0.12, 0.22, 0.27 and 0.13 in the same age groups. Parasitaemia was homogenously detected in different areas of Yopougon. Among all children, 10.1% used a mosquito net (treated or not) the night before the survey and this was protective (OR = 0.52, 95% CI 0.29–0.97). Travel to rural areas within the last three months was frequent (31% of all respondents) and associated with a malaria infection (OR = 1.75, 95% CI 1.25–2.45). Conclusion Rapid urbanization has changed malaria epidemiology in Abidjan and endemicity was found to be moderate in Yopougon. Routine health statistics are not fully reliable to assess the burden of disease, and the low level of the fractions of malaria-attributable fevers indicated substantial over-treatment of malaria.

Informations

• Publié par: biomed
• Publié le: 01 janvier 2006
• Nombre de lectures: 11
• Langue: English

Extrait

BioMed CentralMalaria Journal
Open AccessResearch
Rapid Urban Malaria Appraisal (RUMA) II: Epidemiology of urban
malaria in Dar es Salaam (Tanzania)
1 1 2 3Shr-Jie Wang , Christian Lengeler* , Deodatus Mtasiwa , Thomas Mshana ,
4 4 1Lusinge Manane , Godson Maro and Marcel Tanner
1 2Address: Swiss Tropical Institute, P.O. Box, CH-4002 Basel, Switzerland, The Dar es Salaam Regional/City Medical Office of Health, P.O. Box
3 49084, Dar es Salaam, Tanzania, Medical Laboratory Scientists Association of Tanzania, P.O. Box 65094, Dar es Salaam, Tanzania and The
Muhimbili University College of Health Sciences, P.O. Box 35091, Dar es Salaam, Tanzania
Email: Shr-Jie Wang - [e-mail]; Christian Lengeler* - [e-mail]; Deodatus Mtasiwa - [e-mail];
Thomas Mshana - [e-mail]; Lusinge Manane - [e-mail]; Godson Maro - [e-mail];
Marcel Tanner - [e-mail]
* Corresponding author
Published: 04 April 2006 Received: 02 September 2005
Accepted: 04 April 2006
Malaria Journal 2006, 5:28 doi:10.1186/1475-2875-5-28
This article is available from: http://www.malariajournal.com/content/5/1/29
© 2006 Wang et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Background: The thinking behind malaria research and control strategies stems largely from
experience gained in rural areas and needs to be adapted to the urban environment.
Methods: A rapid assessment of urban malaria was conducted in Dar es Salaam in June-August,
2003 using a standard Rapid Urban Malaria Appraisal (RUMA) methodology. This study was part of
a multi-site study in sub-Saharan Africa supported by the Roll Back Malaria Partnership.
Results: Overall, around one million cases of malaria are reported every year by health facilities.
However, school surveys in Dar es Salaam during a dry spell in 2003 showed that the prevalence
of malaria parasites was low: 0.8%, 1.4%, 2.7% and 3.7% in the centre, intermediate, periphery and
surrounding rural areas, respectively. Health facilities surveys showed that only 37/717 (5.2%) of
presenting fever cases and 22/781 (2.8%) of non-fever cases were positive by blood slide. As a
result, malaria-attributable fractions for fever episodes were low in all age groups and there was an
important over-reporting of malaria cases. Increased malarial infection rates were seen in persons
who travelled to rural areas within the past three months. A remarkably high coverage of
insecticide-treated nets and a corresponding reduction in malarial infection risk were found.
Conclusion: The number of clinical malaria cases was much lower than routine reporting
suggested. Improved malaria diagnosis and re-defined clinical guidelines are urgently required to
avoid over-treatment with antimalarials.
risk of malaria [1]. There is a lack of understanding of theIntroduction
Rapid urbanization brings about major changes in ecol- complex interactions between human social structure, the
ogy, social structure and disease patterns in sub-Saharan environment and malaria infections [2-4]
Africa. It is estimated that 300 million people currently
live in urban areas in Africa and two-thirds of them are at
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central, intermediate and peripheral zones of Dar es
Salaam in 1988 were roughly 6%, 28–41% and 68–74%.
Following the implementation of the first Urban Malaria
Control Project (UMCP) during the period 1988–1994
these rates decreased to 3–10%, 10–25% and 21–46%.
A standard study protocol for Rapid Urban Malaria
Appraisal (RUMA) was developed in June, 2002, based on
a WHO proposal and an Environmental Health Project
draft protocol [13,14]. RUMAs were commissioned by the
Roll Back Malaria Partnership for three Francophone
countries (Côte d'Ivoire, Burkina Faso and Benin) and
one Anglophone country (Tanzania). Each of the four
assessments provided the following information: an over-
view of the urbanization history, an estimate of the frac-
tion of fevers attributable to malaria, parasite rates for
different city areas, an outline of health care services and
highlights of the lessons learned [15]. The aim of the
present study was to compile a minimum dataset to iden-
tify key malaria issues affecting Dar es Salaam within a 6–
10 weeks time frame. In addition, malaria vulnerability in
AFigure 1Mapnophel of selected schools and healthes sp. breeding sites facilities in relation to relation to urban agriculture, socio-economic factors and
Mapo rural exposure were assessed.
Anopheles sp. breeding sites. Source: Adapted from Sattler et
al. [16]. p/s = primary school. HC = health center.
Methods
Study site and sample selection
Dar es Salaam is situated between latitude 6.0°–7.5°S and
Malaria research and control efforts in Tanzania began in longitude 39.0°–39.6°E. It had 2,500,000 inhabitants in
the late 1890s, both in urban and in rural areas [5,6]. In 2002 (a density of 1,800 per sq. km) [16]. The municipal-
the 1970s the malaria problem emerged again on a large ity is divided into three districts: Ilala, Kinondoni and
scale in Dar es Salaam, mainly because of the deteriora- Temeke. To study the heterogeneity of malaria risk, Dar es
tion of the health care system. In 2000, 33% of the popu- Salaam was divided into four zones: centre, intermediate,
lation in Tanzania lived in urban areas [7] and urban periphery and surrounding rural areas. The zones were
poverty was widespread and increasing. More attention is defined on the basis of city characteristics and the poten-
now being devoted again to urban malaria, as uncon- tial malaria risk indicated by an existing Anopheles breed-
trolled urban population growth calls for upscaled and ing site maps (Figure 1) [8,16]. Due to the time
adapted strategies [8,9]. constraints of a RUMA, only one or two representative
health facilities and one or two representative schools in
There are only a few papers concerning malaria epidemi- each zone could be selected (two units were selected when
ology in Dar es Salaam. Okeahialam et al. [10] examined the target sample size could not be reached in a single
218 hospital inpatients and 422 outpatients throughout unit).
1971 and found that 20% of fever cases had malaria par-
Centreasitaemia. Mkawagile [11] reported that during the heavy
rainy season in 1981, about 47.6% of adult outpatients Mtendeni primary school and Mnazi Mmoja Health Cen-
attending Mwananyamala hospital with typical malaria tre are located in Ilala District facing the harbour and
symptoms had parasitaemia; among all outpatients the Mbagala Creek (Figures 1). It is a trader-dominated com-
parasitaemia prevalence was only 27%. Makani [12] mercial centre of the inner city. They are located approxi-
noted that 87% of patients who received antimalarial mately 1–2 km from Msimbazi Valley where Anopheles sp.
treatment in Muhimbili National Hospital for presumed breeding sites are numerous [16].
severe malaria did not have detectable parasitaemia. In
Intermediate zonethat situation, over-diagnosis of cerebral malaria in
patients with neurological dysfunction resulted in over- Mwenge primary school, Kijitonyama Kisiwani primary
treatment of malaria and a neglect of other potentially school, Mwenge dispensary and Kijitonyama dispensary
life-threatening conditions. Yamagata [8] reported that are located in Kijitonyama Ward in Kinondoni District in
the malaria prevalence rates among schoolchildren in the a middle class suburb (Figure 1). There are only few breed-
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ing sites in this area, apart from one with high productiv- Parasite density was defined as the number of parasites
ity near Kijitonyama Kisiwani primary school (1 km per 200 white blood cells. The children were interviewed
away). Mwenge primary school is far from the identified with the assistance of school teachers regarding their fam-
breeding sites. ily situation and malaria infection history.
Periphery Health facility fever surveys
in Temeke District, Ufukoni primary schools and Kigam- The health facility surveys aimed at determining the
boni Health Centre in Kigamboni Ward were chosen (Fig- malaria prevalence among fever cases and the fraction of
ure 1). Kigamboni Ward is a new peri-urban low-incomeattributable fevers [18]. The surveys were carried
suburb south of Dar es Salaam associated with a medium out between July 16 and August 15, 2003. Two hundreds
level of mosquito breeding sites. fever cases and 200 non-fever controls were recruited from
one to two clinics located in each area. About 50% of the
Rural zone sample population was aged ≤ five years. Outpatients with
Buza primary school, Buza dispensary and Makangarawe a history of fever (past 36 hours) or with a measured tem-
dispensary are located at the emerging urban-rural inter- perature of ≥ 37.5°C were defined as cases. After being
face on the hill besi