Description of study sites

Mali is a large landlocked country in West Africa divided in 8 administrative regions with a wide range of malaria transmission patterns as described earlier (Doumbo O., 1991). The infant mortality is estimated to be 99 per 1000 live births and the under-five mortality rate is 176 per 1000 live births (UNICEF, 2011). Malaria accounts for 38.4% of clinic visits with 1,633,423 cases and 2,331 fatalities reported in 2009.

Malaria transmission is highly seasonal, spans usually from June to December with the peak in September-October and varies importantly by regions. Transmission patterns in Mali were classified ‘a priori’ into 5 strata based on the prevalence of prevalence of parasitemia in children aged 2-9 years old (Doumbo O., 1991): 1) in the South and South- West of the country, malaria transmission is holo-endemic with a peak infection prevalence of 70 to 80%and with an annual rainfall total of >1,000 mm and a relatively long rainy season lasting ~6 months and an equally long transmission season; 2) the savannah areas extending between the North and South have an annual rainfall total of ~500 to 1000 mm and a season spanning 3-4 months (Maiga et al., 2010). Malaria transmission in these areas is meso-to hyperendemic with peak infection prevalence of 50-70%; 3) the arid Sahelian areas such as in the Timbuktu region in northern Mali have little rain (<300 mm per year) and very short seasons (2-3 months). Malaria transmission is hypo-endemic or epidemic with a peak infection prevalence not exceeding ~ 5%. Nevertheless, even though the annual rainfall is very low in these arid areas, focal transmission can be maintained throughout the year near permanent water reservoirs

Chapter 1

22

such as ponds and oases (Koita et al., 2012); 4) the bimodal transmission areas: In addition to the characteristics for savannah regions, these areas have virtually year- round transmission due to the combination of seasonal rainfall (from June to October) and irrigation projects for the rest of the year (Sogoba et al., 2007, Ceesay et al., 2012); 5) lastly, in the urban transmission areas such as Bamako malaria transmission is low with peak infection prevalence of ~5-10%.

Our studies were conducted in 9 study sites which have been stratified a priori

(Doumbo et al, 1991) into high (Bougouni, Kita, and Fana), moderate (San, Djenne, Koro, Sangha), and low (Bamako, Timbuktu) transmission settings (Figure 2. 1 & Table 2. 1 in chapter 2). In addition, the site of Bla in moderate transmission area has served for the conduct of the study discussed in chapter 3.

1.7.1 High malaria transmission areas:

Bougouni: Located (Latitude 11.41, Longitude -7.48) in the South of Mali, 180 kilometres south of Bamako. In Bougouni malaria transmission occurs mainly during the rainy season (May-June to October) with the peak in October. The study described in chapter 2 was conducted from September 2006 to March 2007 in the 3 community health centers and the reference health center of the town of Bougouni. This site was identified for the pilot implementation of IPTp at community level by “Save the Children” described in chapter 6. The population of the urban community of Bougouni was estimated to be 59,679 in 2009 with 2,984 pregnant women. The number of assisted deliveries recorded in the four health structures was estimated to be 1,021 in 2007.

Kita: The study described in chapter 2 and 6 was conducted from July 2009 to January 2010 in the reference health center and the two community health centers of the town of Kita (Latitude 13.05, Longitude -9.48). Located 182 kilometers west of Bamako, this site started the IPTp-SP strategy in 2004 with the support of UNICEF. The population of the commune of Kita is estimated to be 48,947 in 2009 with 2,448 pregnant women. In 2009, the number of assisted deliveries was estimated to be 1,358 in the three health centers where the study took place.

Fana: Located (Latitude 12.77, Longitude -6.95) 130 kilometres east of Bamako, Fana is a semi urban area where malaria transmission is intense, with similar rainfall as

Chapter 1

23

the above sites. The chapter 2 study was conducted from November 2005 to February 2006 in the reference health centre which had received more than 1,500 ANC visits and 869 deliveries in 2006. The frequency of the Pfcrt K76T mutants in Plasmodium falciparum infections in peripheral blood was 68.8% (11/16) and 100% (16/16) in the placenta (p = 0.004). The frequency in peripheral blood of the DHFR N51I mutation was 12.5% (2/16) and 18.8% (3/16) in the placenta (p=0.12). The frequencies of the DHPS A437G mutants were similar in both sites 25% (4/16). No DHPS K540E and DHFR 164L mutations were found (Doumbo, 2013).

1.7.2 Moderate malaria transmission areas: #

Here the surveys described in chapter 2 and 6 were conducted from September 2006 to March 2007 in the health districts of Koro, Djenne, and San.

Since 2003, the sites of Koro (Latitude 13.94, Longitude -3.02) and Djenne

(Latitude 13.9, longitude -4.55) were part of a UNICEF funded pilot implementation program of IPTp as part of their project on “Child and Mother hood Survivor Project”. Both Koro and Djenne belong to the Mopti region. The town of Djenne becomes an island during the rainy season resulting from the annual flood produced by Bani river. In 2009, the population and number of pregnant women was estimated to be ~62,681 inhabitants and 3,135 pregnant women in Koro and 32,944 and 1,650 in Djenne, respectively. In both sites, malaria transmission lasts from June to October with the peak in September.

The site of San (Latitude 13.3, Longitude -4.9) also benefitted from the support from UNICEF’s IPTp pilot program since late 2004. In the town of San, two surveys had been conducted, the first from September 2006 to March 2007 and the second from July 2009 to January 2010. This area has similar characteristics of rainfall and malaria transmission pattern as Koro and Djenne. In 2009, the commune of San had 68,078 inhabitants and 3,404 pregnant women. The number of ANC visits, and assisted deliveries in the town of San was 2,019 and 1,042 in 2009. This site belongs to Segou region as well as the following site.

The site of Bla is located (Latitude 12.95, Longitude -5.75) 320 kilometres east of Bamako in the Segou region. The district has had the support from UNICEF since 2001,

Chapter 1

24

but IPTp implementation only started in 2004. The trial comparing 3 versus 2 doses of SP described in chapter 3 was conducted from April 2006 to March 2008 in the two main health facilities in Bla (Diakite et al., 2011), which serve a population of approximately 39,000 inhabitants.

Sangha (Latitude 14.66, Longitude-3.31) is a rural commune, 800 kilometers north-east of Bamako in the district of Bandiagara, in Mopti region. The commune is known as a centre for traditional religion with many temples and shrines, and as a base for visitors to the local Dogon villages. The commune of Sangha had a population of 32,513 inhabitants in 2009 with an estimated 1,626 pregnant women. Malaria transmission occurs during the rainy season which lasts from July to October with annual rainfall of ~700 mm3. The prevalence of malaria disease in the general population was 14% in 2008 and entomologic inoculation rate (EIR) measured in Bandiagara was 1.1 infected bites per person year (Yaro A.S., 2003). IPTp-SP implementation started in 2004 with the support of UNICEF. The study described in chapter 2 was conducted from June 2006 to February 2007 in the community health center.

1.7.3 Low or epidemic malaria transmission areas:

In Bamako (Latitude 12.65, Longitude -8.00), two surveys were conducted, the first in January 2005 in the community health centre of Banconi having 11,084 antenatal visits and 3,506 deliveries in 2011, and the second from March to November 2009 in the community health centre of Sabalibougou which recorded 3,498 ANC visits and 1,109 deliveries in 2009. The community health centre covered a population of 72,995 in 2008. Although Bamako is characterized by heavy rainfall (more than 1,000 mm per year), malaria transmission is low because of its urbanisation (Doumbo O., 1991, Pond, 2013). Malaria transmission spans from June to December with a peak in October corresponding to the end of the rainy season.

In the Timbuktu region, data were collected from January to March 2005 in the reference health centre of Timbuktu (Latitude 16.77, Longitude -3.00) and Niafunke (Latitude 15.93, Longitude -3.99) which is located 200 kilometres west of Timbuktu by the left side of the river Niger. Timbuktu is part of the Sahara, with an average temperature of 38oC (varying from 25oC to 45oC) in the hot dry season (March, April, and

Chapter 1

25

May) and annual rainfall of ~300 mm (Koita et al., 2012). Malaria transmission is thought to be very low or epidemic (Doumbo O., 1991, Koita et al., 2012). Infections with P.vivax

have been reported in this area (Bernabeu et al., 2012). Although Timbuktu is indicated to be a semi-arid region (Doumbo O., 1991) as are the other regions in northern Mali, the recent arrival of large irrigation projects permitting rice culture during the dry season has created a massive body of water formed by rice paddies. This can maintain mosquito population abundance after the rainy season to levels needed to sustain malaria transmission during the dry season.