Global Malaria Control: It’s Time To Cast Down The Net

by Adepoju Paul Olusegun

Maybe as her own demonstration of love during the Valentine season, the First Lady of Nigeria – Dame Patience Jonathan on Sunday 13th day of February 2011 turned a portion of Aso Rock into a repository for insecticide-treated nets (ITNs) that were subsequently distributed to some categories of Nigerian women. Her love gift is one out of the numerous efforts by various individuals, groups, communities, societies, agencies, governments, stakeholders and non stakeholders alike, in the fight against malaria that has decisively and ruthlessly dealt with the third world tropical countries of sub-Saharan Africa.

Public health officials had hoped to wipe out malaria during the 20th century. However, malaria parasites have developed several defense mechanisms against many anti-malarial drugs. This response, known as drug resistance, makes the drugs less effective. In addition, the Anopheles mosquitoes that transmit the disease have become resistant to many insecticides. Hence malaria remains a global health problem although Nigeria and other sub-Saharan Africa countries are worst hit, and public health efforts today focus on controlling it.

Although a worldwide effort is under way to develop potent vaccines that protect against malaria, the prospect so far has not been bright and medical scientists are still several light years away from making reliable, stable and safe malaria vaccine available. In the meantime however, researches by the WHO and other bodies have found that sleeping under mosquito bed nets treated with insecticide can greatly reduce deaths from malaria, especially among children.

Nets treated with insecticides—known as insecticide treated nets (ITNs) — were developed in the 1980s for malaria prevention. Insecticide-treated nets (ITN) are estimated to be twice as effective as untreated nets, and offer greater than seventy per cent protection compared with no net. These nets are dip treated using a synthetic pyrethroid insecticide such as deltamethrin or permethrin which will double the protection over a non-treated net by killing and repelling mosquitoes. ITNs have been shown to be the most cost-effective prevention method so far against malaria and are part of WHO’s plan towards the realization and actualization of Millennium Development Goals (MDGs).

Unlike ordinary mosquito nets, ITNs protect people sleeping under the net and simultaneously kill mosquitoes that come in contact with the net. Some protection is also provided to others by this method, including people sleeping in the same room but not under the net. However, mathematical modelling has suggested that disease transmission may be exacerbated after bed nets have lost their insecticidal properties under certain circumstances including direct sunlight and repeated washing.
Online searches for negative side effects associated with the usage of insecticide treated nets often give no clear-cut results as Google search results usually redirect users to web pages that speak glowingly of the potency, efficacy and safety of ITNs. These often give the impression that ITNs are trouble-free; and more effective than the much elusive malaria vaccine. But in the real sense, this is not the case – ITNs have their own Pandora box that has been discouraging many Africans from embracing its usage. These issues are economically, socially, psychologically, chemically and medically relevant.

It’s only in TDR News (a WHO tropical disease research newsletter) and other similar publications that the usage of insecticide treated nets is improving in Africa and other parts of the world. The data, though true, are often confusing and they fail to present the true picture of the status of ITN usage in Africa. In Nigeria for instance, the Roll Back Malaria programme, Society for Family Health, Nothing But Nets, World Health Organization, and several others distribute nets freely yet more Nigerians prefer to buy and burn mosquito coils. . . even on credit, than to get ITNs free of charge. Some things must be wrong somewhere! The cost is one of such.

Some experts argue that international organizations should distribute ITNs to people for free in order to maximize coverage (since such a policy would reduces price barriers), others insist that cost-sharing between the international organization and recipients would lead to greater usage of the net (arguing that people will value a good more if they pay for it). Additionally, proponents of cost-sharing argue that such a policy ensures that nets are efficiently allocated to those people who most need them (or are most vulnerable to infection). Through a “selection effect”, they argue, those people who need the bed nets most will choose to purchase them, while those who need it less will surely opt out.

In real practice however, this is not the case. Although many Nigerians are at risk of malarial infection if left unprotected, only a minute fraction of the demography purchase the nets and if the notion of “needs” is put into consideration, most Nigerians at risk don’t need the net. Apart from the lack of interest, tales of those who had bad experiences with the nets are enough to discourage others from using ITNs.

Insecticide treated mosquito nets have very small pore sizes that reduce air flow to a large extent. Hence sleeping under ITNs is hotter than sleeping without one. This is uncomfortable in tropical countries like Nigeria with epileptic, erratic, unstable and unreliable power supply to power electric fans and air-conditioning units. For people who have difficulty with breathing and those who love free flow of air while asleep, the alternative for reducing mosquito bites is to use a fan to increase air flow as mosquito prefer still air. To them, mosquito nets are no options when the fan is not on. They utilize alternatives which include applying insect repellent cream to the skin, “flitting” the room with Raid or Mortein, or burning the cheap but hazard-prone coil.

The chemical component of the insecticide treated nets is another issue of concern. Although ordinary literature searches often yield no negative results, interaction with users give an expose on what they face. In the first few days of usage, ITN (Permanet®) users complain of serious overwhelming burning sensation. The long-term effect of this, especially the longer term impact it has, on the user calls for concern; it questions the justification for users to continue to sleep under the controversial nets.

The burning sensation could be traced to the chemical that the net has been impregnated with. Several patients also present with bloated swollen painful faces of varying proportions. Medical books are inconclusive on whether users should tremble and panic, or to consider the disproportionate bloated face which often corrects itself later on, as just “one of those things”. The insecticide content of ITNs that are distributed in Nigeria has menthol as its solvent. This is a very useful chemical, but constant exposure to it has been associated with several side effects.

Menthol in the form that is being used in ITNs has also been associated with breathing problems, difficulty swallowing, chest tightness, irritation in the nose, redness and irritation at site of application, etc. Over the years, various health professionals, institutions and bodies had reiterated the fact that allergic reactions cannot be associated with the usage of ITNs, yet numerous instances had been experienced in practice when users present with blisters and several other dermal (skin) reactions.

Apart from reactions, the active pesticide in Africa’s major ITNs

– deltamethrin – also has some associated risks to the user, and malaria control itself. It is used as one of a battery of pyrethroid insecticides in control of malarial vectors. The major challenge it is currently facing in recent times has been resistance, although advocates of ITN usage are playing it down, hence it’s not yet a huge press issue.

Resistance to deltamethrin is now extremely widespread and threatens the success of worldwide vector control programmes. In medical science terms, resistance has been characterised in several important vectors of malaria. Resistance include thickening of the cuticle of the vector to facilitate less permeation of the insecticide, metabolic resistance via over-expression of metabolising P450 mono-oxygenases and glutathione-S-transferases, and the sodium channel mutations which render the action of insecticides ineffectual, even when co-administered with piperonyl butoxide. Characterisation of the different forms of resistance has become a top priority in groups studying tropical medicine due to the high mortality of those who reside in endemic areas. Field caught Permethrin-Resistant Anopheles gambiae over-express CYP6P3, a P450 that metabolises pyrethroids.

The simple explanation for the complex medical science terms of previous paragraph is that malaria vectors (mosquitoes), and the malaria parasites are devising methods of evading the activities of the chemicals that has been saddled with the responsibility of killing mosquitoes in and around ITNs. Apart from making the nets, in the nearest future to be nothing but heat-producing potentially risky ineffective extremely tight fish nets, resistance also create new challenges that could make the search for vaccines more difficult, maybe impossible, if the malaria parasite is also undergoing mutation (changes) that could compromise its well understood pathogenesis (the stages through which an infective organism go through to cause infection and establish a disease state).

Chemical poisoning is another issue of paramount concern in the usage of ITNs. Deltamethrin (mentioned earlier) is a neurotoxin, it attacks the nervous system. Skin contact can lead to tingling or reddening of the skin local to the application. If taken in through the eyes or mouth, which might occur when children “play” with the net, a common symptom is facial paraesthesia, which can feel like many different abnormal sensations, including burning, partial numbness, “pins and needles”, skin crawling, etc. According to recent medical case reports, chronic exposure to pyrethroid insecticides like deltamethrin can cause motor neuron disease.

Apart from medical and chemical complications, there are psychological, social and safety issues to put into consideration. Many users feel incarcerated and restricted, like prison inmates, whenever they sleep under the net. This is of paramount concern for the claustrophobic members of the public that are depressed, and uncomfortable when confined to a “safe” secluded area – a bed draped with chemical laden nets. Is it right to protect them from malaria and expose them to their much dreaded phobia?

Also, the instructions on how to sleep under the net make the whole idea too bogus and excessive for “ordinary malaria”. In the same vein, lack of extensive freedom and fear of being caught within the net when there are house accidents like fire accidents create more bottlenecks for the WHO’s desire to see that every African child sleep under an ITN in the nearest future.

Recently, health experts across several tropical countries in Africa began to advocate the incorporation of sweetly scented mosquito insecticides into household anti-malaria plan in addition to the usage of insecticide treated nets. Apart from sleeping under the nets, they recommend that the room should be flitted with insecticides like Raid or Mortein three times in a week. This budding phenomenon connotes that going by the current pace, sooner than later, families would have to assign a sizeable portion of their annual household budget for the fight against malaria and its vectors. There is the risk of making malaria a very expensive disease to treat, just like cancer and Alzheimer’s disease. And if this happens, Africa would be the worst hit.

In South Africa, residues of deltamethrin were found in breast milk. Lactating babies ingesting such milk during lactation are bound to have several medical aberrations that might cause permanent deformation to the innocent children. It is quite disappointing that apart from insecticide treated nets, the only thing that has come out of the various multibillion dollar malaria research labs across the world since the 1980s has been more insecticide treated nets. Like other infections associated with increased morbidity and mortality, malaria deserves new thoughtful capricious changes that catch the parasite unawares instead of the current predictable measures that are both archaic and potentially harmful for the next generation.

Like most inept and supercilious African leaders that are unperturbed with the status quo, malaria researchers with their continual reliance on insecticide treated nets as viable protective measure against malaria infection are sitting on a malaria time bomb which can escalate beyond imaginable proportions. The nets ought to be temporary stop gap measures until a vaccine is discovered; but as it is gradually becoming evident, the WHO, other health organizations and government health ministries had embraced it as the last hope for those at risk of contracting malaria. If this is true, then they’ve not done enough.

You may also like

Leave a Comment