MALARIA ELIMINATION IN ZANZIBAR - Soper Strategies

FIGURE 2.1: AVERAGE MONTHLY RAINFALL FOR ZANZIBAR
RAINFALL (MM)
350
300
250
200
150
100
50
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
AVERAGE RAINFALL (MM)
In 2002, Zanzibar was estimated to have 981,754 inhabitants
and a population density of 370 inhabitants per square kilometer
(National Bureau of Statistics, 2002). Forty percent were
estimated to be living in urban areas. The population growth
rate was high, 3.1%, and this was mostly attributed to a high
fertility rate of 5.3 children/women. The projected population
for 2008 was 1,193,127. The average household size in 2004 was
5.5 members. About a quarter of adults in Zanzibar are reported
to have no education but almost 76% of adults can read and
write in at least one language. The basic education enrollment
for the pupils 7 to 16 years of age was 78.4% (Office of the Chief
Government Statistician, 2006).
Residents of Zanzibar have a life expectancy of approximately 57
years. Infant mortality rate has fallen from 83 per 1,000 live births
in 1999, to 61 per 1,000 live births in 2005 (National Bureau
of Statistics and ORC Macro, 2005) Although 97% of women
receive ante-natal care (ZMCP, 2008), only 50% of deliveries
are assisted by a medical professional and the maternal mortality
rate remains high at 110/100,000 live births (National Bureau of
Statistics and ORC Macro, 2005). HIV prevalence is estimated
to be below 1%. The Household Budget Survey performed in
2004 showed that about one-fifth of people suffered at least one
kind of illness in the four week period preceding the survey; with
variations of 23% in the rural population as compared to 13% in
urban populations. More than four-fifths of individuals who were
ill consulted with a health care provider, mainly through primary
health care (PHC) units. Only 16% consulted with a provider
through private health facilities. Seventy percent of all households
(50% in rural areas, and more than 90% in urban areas) were
located within 2 kilometers from their health centre (Office of the
Chief Government Statistician, 2006).
A quarter of the labor force is in agriculture, mainly farming and
livestock keeping, and only one in ten is an “employee”, employed
either by the government, public enterprise, non-governmental
organizations or faith-based organizations. Although work in
agriculture is the largest single economic activity, wage labor
is the most important source of cash income and one-third of
the households reported running a business (Office of the Chief
Government Statistician, 2006).
ZANZIBAR MALARIA EPIDEMIOLOGY
Until recently, malaria in Zanzibar has been characterized by
perennial stable transmission. The introduction of ACT as first-
line treatment, the use of long-lasting insecticide-treated nets by a
large proportion of pregnant women and under fives and the high
coverage of indoor residual spraying is thought to have changed
the endemicity pattern from hyper- to hypo-endemic (Bhattarai
et al., 2007) with malaria prevalence estimates of below 1%; 0%
in the Stonetown area and around 3% in Northern Pemba (see
Figure 3) (ZMCP, 2008). Nevertheless, the entire population
remains at risk of malaria and it is assumed that due to past
transmission patterns older age groups still have some immunity
and children below the age of five and pregnant women remain
more vulnerable to infection.
FIGURE 3: MALARIA PREVALENCE BY DISTRICT (ZMCP, 2008)
Unguja
Urban
0%
North B
0.1 - 0.2%
West
0%
North A
0.6 - 2.5%
Central
0.1 - 0.2%
Prevalence of
Plasmodium Falciparum
South
0.1 - 0.2%
0%
Pemba
Michewni
2.6 - 3.7%
Wete
0.6 - 2.5%
Chakechake
0.3 - 0.5%
Mikoani
0.3 - 0.5%
Introduction
0.1 - 0.2% 0.3 - 0.5% 0.6 - 2.5% 2.6 - 3.7%
Plasmodium falciparum is the predominant species and
accounts for 97% of all malaria infections. The only other species
found is P. malariae. (ZMCP, 2008). Anopheles gambiae sensu
lato, An. funestus and An. coustani are the only malaria vectors on
Zanzibar (Ilumba et al., 2007). Members of the An. gambiae s.l.
include An. gambiae s.s.; An. arabiensis; and An. quadriannulatus.
Because of the slightly different rainfall patterns between Pemba
(uni-modal) and Unguja (bi-modal) the transmission patterns
also differ. Pemba has a single transmission season while the
evaluation of entomological inoculation rates on Unguja showed
two peaks in malaria transmission with high biting rates during
the long rainy season and lower ones during the short rains.
In 2000, the overall treatment failure to chloroquine was found to
be 60% in a 14-day efficacy trial and consequently the Zanzibar
MOHSW decided in November 2001 to change both first- and
second-line treatment guidelines for uncomplicated malaria from
chloroquine (CQ) and sulfadoxine-pyrimethamine (SP) to ACT
(ZMCP, 2002). A combination of Artesunate and Amodiaquine
(AS-AQ) was chosen as the first-line treatment while for secondline
treatment Artemeter and Lumefantrine (Coartem®) was
recommended. Quinine is still used to treat severe malaria
and malaria in the first trimester of pregnancy. SP is only used
for intermittent preventative treatment for pregnant women
(IPTp). The ACT policy was implemented in September 2003
making Zanzibar one of the first regions in sub-Saharan Africa
to recommend routine use of ACT. In the same year a study
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