BED NETS (LLINS/ITNS) COVERAGE AND THE IMPACTS OF THESE BED NETS IN PREVENTING MALARIA

CHAPTER ONE

INTRODUCTION AND LITERATURE REVIEW

Malaria is a major international public health problem. Globally, an estimated 3.4 billion people are at risk of malaria. WHO estimates that 207 million cases of malaria occurred globally in 2012? Most cases (80%) occurred in Africa followed by South-East Asia region (13%) and the Eastern Mediterranean region (6%).

About 9% of estimated cases globally are due to P. vivax, although the proportion outside the African continent is 50%. (WMR, 2013). There were an estimated 627 000 malaria deaths worldwide in 2012.  It is estimated that 90% of deaths in 2012 were in the African Region, followed by the South-East Asia Region (7%) and Eastern Mediterranean Region (3%). About 482 000 malaria deaths were estimated to occur in children under 5 years of age worldwide. Most deaths are due to P. falciparum; however, P. vivaxis increasingly recognized as a cause of severe malaria and death.

In Cameroon, malaria is the leading cause of morbidity and mortality in among the most vulnerable groups, children and pregnant women. It is endemic throughout the country, with almost all Cameroonians reporting at least one episode annually. (WHO WMR, 2013).

1.2.4. Pathogenesis

Fever is caused by release of waste material when infected cells rupture in the blood. Cerebral malaria is caused by clotting of red blood cells in the brain blood capillaries as a result of the malaria infection. Severe anaemia is caused by destruction of both infected and uninfected cells by the parasite or by the body itself. The failure of other organs, like kidneys, liver and spleen, is caused by the flood of waste materials and the clotting of blood capillaries, to the point where the body can no longer cope.

1.2.5. Clinical Manifestation

From infection to first symptoms (incubation period) is usually 7-14 days after initial exposure in a malaria-endemic area and as late as several months or more after departure. Malaria is characterized by fever and influenza-like symptoms, including chills, headache, myalgias, and malaise; these symptoms can occur at intervals (Paul &Kathrine, 2014).

Uncomplicated disease may be associated with anaemia and jaundice. In severe disease, seizures, mental confusion, kidney failure, acute respiratory distress syndrome, coma, and death may occur reports the WHO Practical Handbook Of Management Of Severe Malaria (2013).

1.2.6 Diagnosis

In the past, fever was equated with malaria in many endemic countries. In early 2010, WHO recommended that every suspected malaria case be confirmed by prompt parasitological confirmation by microscopy or a rapid diagnostic test (RDT) prior to treatment. Only in areas where diagnostic testing is not possible should malaria treatment be initiated solely on clinical suspicion.

Routine parasitological confirmation of malaria is based on either identification of parasites in blood films examined by light microscopy or detection of parasite antigens with RDTs.

1.2.7 Treatment

Malaria can be treated effectively early in the course of the disease, but delay of therapy can have serious or even fatal consequences. Specific treatment options depend on the species of malaria, the likelihood of drug resistance (based on where the infection was acquired), the age of the patient, pregnancy status, and the severity of infection (Paul and Kathrine ,2014).

1.2.8 Uncomplicated Malaria

Antimalarial combination therapy is the simultaneous use of two or more blood schizontocidal medicines with independent modes of action and, thus, differentbio chemical targets in the parasite.

Uncomplicated P. falciparum malaria should be treated with an ACT. The five ACTs currently recommended for use by WHO are:

• ■ Artemether plus Lumefantrine, (AL).
• ■ Artesunate plus Amodiaquine, (AS+AQ).
• ■ Artesunate plus Mefloquine, (AS+MQ).
• ■ Artesunate plus Sulfadoxine-Pyrimethamine, 7(AS+SP).
• With sufficient evidence on safety and efficacy of
• ■ Dihydroartemisinic plus Piperaquine.(DHA+PPQ), added to the list of ACTs options recommended for the treatment of uncomplicated falciparum malaria (WHO WMR, 2013).

1.2.9. Complicated Malaria

It is essential that effective, parenteral (or rectal) antimalarial treatment in full doses is given promptly in severe malaria. Two classes of medicines are available for the parenteral treatment of severe malaria:

• The cinchona alkaloids (quinine and quinidine) and
• The artemisinin derivatives (artesunate, artemether and artemotil).

With high quality evidence, it is strongly recommended that Intravenous artesunate should be used in preference to quinine for the treatment of severe P. falciparum malaria in adults and children in all geographical settings.

1.2.10. Prevention

The goal of malaria prevention is to prevent malaria caused by all species of Plasmodium. Malaria prevention consists of a combination of vector control measures and chemoprophylaxis. WHO recommends integrated strategy to control and eliminate malaria, which includes vector control interventions, preventive therapies, diagnostic testing, treatment with quality- assured artemisinin-based combination therapies (ACTs),and strong malaria surveillance, (WHO WMR, 2013).

1.2.11.  Malaria prevention through vector control

The two most powerful and most broadly applied interventions for malaria vector control prevention are insecticide-treated mosquito nets (ITNs) and indoor residual spraying (IRS).Other vector control methods are environmental management, biological control and larval management (chemical control).

1.2.12Indoor Residual Spraying, IRS

Chemical control of adult female mosquitoes has been the most widely successful vector control method since the 1940s. The rationale for IRS is based on the behaviour of those Anopheles species that rest on walls before or after biting humans.

The most common practice is indoor residual house spraying (IRS), in which the inside walls, the ceiling, and sometimes the outside eaves, porches, and nearby animal sheds are sprayed with a persistent insecticide. An appropriate insecticide should be highly toxic to the insect, safe for humans and non-target organisms, persistent on the wall or ceiling surface, acceptable to the inhabitants of the house, easy to apply, and fairly inexpensive (Rozendaal 1997).

1.2.13. Insecticide-treated nets, ITNs.

Because of the nocturnal feeding habits of Anopheles mosquitoes, malaria transmission occurs primarily between dusk and dawn. Contact with mosquitoes can be reduced by using mosquito bed nets during evening and night time hours, (preferably insecticide-treated nets), and wearing clothes that cover most of the body.An insecticide-treated net is a mosquito net that repels, disables and/or kills mosquitoes coming into contact with insecticide on the netting material. There are two categories of ITNs: conventionally treated nets and long-lasting insecticidal nets:

A conventionally treated net is a mosquito net that has been treated by dipping in aWHO recommended insecticide. To ensure its continued insecticidal effect, the net should be re-treated after three washes, or at least once a year.

A long-lasting insecticidal net is a factory-treated mosquito net made with netting material that has insecticide incorporated within or bound around the fibres. The net must retain its effective biological activity without re-treatment for at least 20 WHO standard washes under laboratory conditions and three years of recommended use under field conditions.Consistent use of ITNs can reduce malaria transmission by up to 90% (Gimning et al 2003) and overt as much as 44% of all-cause mortality among children under five (Lengeler 2002).

There is also evidence that if more than 80% of households in an area sleep under an ITN, malaria transmission is significantly reduced, which can benefit people who do not use an ITN themselves according to CDC (2008), Dipping nets in a solution of a parathyroid insecticide transforms the net from a simple physical barrier into a physical and chemical barrier that can repel or kill the female anopheles mosquito, which is responsible for transmitting malaria parasiteTo meet the target of universal access, WHO recommends that one LLIN be distributed for every two people at risk of malaria in the target population. LLINs procured through public health funds should be provided free of charge to all populations at risk.

1.2.14. Bed net (LLINs/ITNs) Distribution

A total of 88 countries distribute ITNs free of charge, including 39 of 44 countries in the African Region with on-going malaria transmission (WHO WMR, 2012). In 83 countries, ITNs are distributed to all age groups; in64 of those countries, the ITNs are distributed to all age groups through mass campaigns.

In Cameroon, while 52% of households possess any net, only 36% own an ITN, and only 28% of children below 5 years were reported to have slept under a net, with 21% under an ITN. One of the objectives of the Ministry of Health is to have 80% of children below five years sleeping under LLINs by 2015 (Cameroon Health sector Strategy, 2009).

Thus, to increase bed net possession, the NMCP launched in August 2011 a national campaign for distribution of free LLINs to households, over eight million free long-lasting insecticide treated nets (LLINs) were distributed in an effort to reduce the significant morbidity and mortality burden of malaria in the country. However, one of the greatest challenges is its effective use by individuals.

Previous studies have shown that several factors influence net use. Household factors include: household size, age, education and occupation of household head, Other factors include climate and temperature associated with increased net use in the rainy season or reduced use during excessive heat (Pulford J. et al., 2011),as well as socio-cultural and socio-economic activities which can temporary reduce net use even among regular net users (Dunn E., Le Mare A., and Makungu C., 2011).

1.2.15. Maintaining high coverage

A number of countries have embarked on mass distribution campaign strategies as a means of rapidly increasing LLIN coverage. Because of the lifespan of LLINs (3–5 years), it is critical to ensure mechanisms for their replacement. Of

Experience has shown that possession and appropriate use of ITNs do not automatically go hand-in-hand. Many people who received ITNs did not sleep under them, re-sold them, reduced their efficacy through inappropriate washing practices, or failed to replace them when they became damaged or torn.

1.3. RATIONALE

Despite the free distribution of nets, the prevalence of malaria in the Mile 16 neighbourhood is still very high and the population particularly pregnant women and children below 5years are still at risk of having malaria This gives reason to investigate the impact of the nets in preventing malaria in that area.

1.4. OBJECTIVES

1.4.1. Main Objective

To determine bed nets (LLINs/ITNs) coverage and the impacts of these bed nets in preventing malaria.

1.4.2. Specific Objectives

1. To determine the coverage and use of bed nets in the study area.
2. Determine pregnant women and children are involved.
3. Impact of bed nets in reducing the incidence of malaria.

1.5. Hypothesis

Bed nets do not have an impact in the incidence of malaria in the Mile 16 neighbourhood.