**1. Introduction**

Malaria is a parasitic disease confined mostly to the tropical areas, caused by *Plasmodium* parasites and transmitted by *Anopheles* mosquitoes. In 2010, nearly 655.000 human deaths, mainly of children ≤5 years of age, were registered among more than 200 million cases worldwide of clinical malaria; the vast majority of cases occurred in the African Region (81%) and South-East Asia (13%), and 91% of them were due to *P. falciparum*, the most viru‐ lent among *Plasmodia* strains (WHO, 2011a).

In order to achieve malaria eradication, an ambitious objective which has been prosecuted since 2007 by the Bill and Melinda Gates Foundation, the World Health Organization (WHO) and the Roll Back Malaria association, several strategies are currently adopted, and a major role is played by vector control (Roberts & Enserink, 2007; Greenwood, 2008; Khad‐ javi et al., 2010; Prato et al., 2012). Dichlorodiphenyltrichloroethane (DDT), one of the insec‐ ticides recommended by the WHO for indoor residual spraying or treated bednets approaches against *Anopheles* mosquitoes, is currently used by approximately fourteen countries, and several others are planning to reintroduce it as a main anti-vector tool; how‐ ever, it strongly polarizes the opinion of scientists, who line up on the field as opponents, centrists or supporters, highlighting DDT health benefits or putative risks depending on their alignment (Bouwman et al., 2011). In this context, the present chapter will review the current knowledge on DDT use, and will suggest some possible future directions to be taken for malaria vector control.

© 2013 Prato et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Prato et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The chapter will open on a short illustration of the *Plasmodium* life cycle, which occurs either in mosquito vector (sexual reproduction) or in human host (asexual replication). Since anti‐ vector control measures are directed to mosquito killing, *Plasmodium* sexual cycle will be pri‐ oritized. Therefore, the insecticides currently allowed for malaria vector control, including organochlorines (OCs), organophosphates (OPs), carbamates (Cs), and pyrethroids (PYs), will be briefly described. After such a brief introduction, a special attention will be paid to DDT. Formulation, cost-effectiveness, mechanisms of action, resistance and environmental issues will be discussed. The big debate among pro-DDT, DDT-centrist, or anti-DDT scien‐ tists will be examined. In this context, the state-of-the-art of knowledge on DDT toxicity will be analyzed, and few tips on possible alternatives to DDT will be given.

Hommel, 2011). The intensity of malaria parasite transmission varies geographically accord‐ ing to vector species of *Anopheles* mosquitoes. Risk is measured in terms of exposure to in‐ fective mosquitoes, with the heaviest annual transmission intensity ranging from 200 to >1000 infective bites per person. Interruption of transmission is technically difficult in many parts of the world because of limitations in approaches and tools for malaria control. In ad‐ dition to ecological and behavioral parameters affecting vectorial capacity, *Anopheles* species also vary in their innate ability to support malaria parasite development. Environmental conditions such as temperature in mosquito microhabitats serve to regulate both the proba‐

DDT as Anti-Malaria Tool: The Bull in the China Shop or the Elephant in the Room?

**Merozoites Gametocytes**

In the mosquito, three phases of life of the parasite involve developmental transitions be‐ tween gametocyte and ookinete stages, between ookinetes and mature oocysts, and between oocysts and sporozoites. When a female Anopheles sucks the blood of a malaria patient, the gametocytes also enter along with blood. They reach the stomach, and gamete formation takes place (Aly et al., 2009). Two types of gametes are formed: the microgametocytes (male) originate active microgametes, and the megagametocyte (female) undergoes some reorgani‐ zation forming megagametes. Fertilization of the female gamete by the male gamete occurs

Salivary gland**: Sporozoites**

New infection

**3**

Midgut: Gamete-Oocyst

http://dx.doi.org/10.5772/53241

333

**2**

bility and timing of sporogonic development (Rogier & Hommel, 2011).

Intra-erythrocytic Cycle

**Hepatic**

**Schizonts**

**Sporozoites**

**Figure 1.** *Plasmodium* parasite life cycle.

**1**

Taken altogether, these notions should help the reader to arise his own opinion on such a hot topic, in order to feed the ongoing debate. In areas endemic for malaria, is DDT dangerous as the bull in a China shop? Or perhaps is it worth using DDT, since its advantages related to malaria prevention are self-evident as the elephant in the room? Any answers aimed at finding the most practicable way to fight malaria through vector control are urgently required.
