The Programme to Eliminate Lymphatic Filariasis
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History of the disease
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Lymphatic filariasis has been a worldwide misfortune of civilization for thousands of years. Described on the pharaonic murals of Egypt and in the ancient medical texts of China, India, Japan and Persia, elephantiasis and hydrocoele were first associated with parasitic filarial worms and their mosquito vectors in the late 19th century by French, English and Australian physicians working with patients from Cuba, Brazil, China and India. [Top]
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| Magnitude of the problem |
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More than 80 countries are affected |
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120 million people have developed the disease |
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1.2 billion people are at risk |
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The successes of the elimination programmes in China and Japan have resulted in saving hundreds of millions of people from lymphatic filariasis. |
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Lymphatic filariasis, also known as elephantiasis, now puts at risk more than a billion people in at least 80 countries. There are more than 120 million have been affected by lymphatic filariasis and over 40 million of them are seriously incapacitated and disfigured by the disease. One third of those infected live in India, one-third in Africa and most of the remainder in South Asia, the Pacific and the Americas. In tropical and subtropical areas where lymphatic filariasis is well established, the prevalence of infection is continuing to increase. |
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Globally the infection has been recognized as the second leading cause of permanent and long term disability, with the deforming, mutilating disease of the limbs and genitals resulting not only in physical crippling but also in serious psycho-social crippling. [Top] |
| The disease |
The disease caused by thread like parasitic filarial worms, Wucheria Bancrofti, that live most exclusively in humans. These worm lodge in the lymphatic system, the network of nodes and vessels that maintains the delicate fluid balance between the tissues and blood, and which is an essential component for the body’s immune defense system. They live for 4-6 years, and the female worms release millions of baby worms (immature microfilariae) that circulate in the blood.
In its most obvious manifestations, lymphatic filariasis cause enlargement of the entire leg or arm, the genitals, vulva and breasts. In endemic communities, 10-50% of men and up to 10% of women can be affected. The psychological and social stigma associated with these aspects of the disease is immense. In addition, even more common that the overt abnormalities is hidden, internal damage to the kidneys and lymphatic system caused by the filariae. [Top] |
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Transmission of the life cycle
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Mosquitoes that bite infected humans and pick up the microfilariae from the blood transmit the disease. The microfilariae ingested by the mosquito pass to the stomach. After a period of approximately two weeks the parasites migrate to the head of the mosquito and position themselves in the mouth parts ready to enter the punctured skin of the next individual when the mosquitoes bites, thus completing the cycle. [Top]
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Signs and symptoms
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Once outward signs of the disease are visible, it’s too late; it cannot be cured. However, you can relieve the suffering through appropriate treatment, which prevents further complications due to infections.
The development of the disease itself in humans is still something mysterious to scientists. Though the infection is generally acquired early in childhood, the disease may take years to manifest itself. Indeed many people may never acquire outward clinical manifestations of their infections. Even though there may be no clinical symptoms, studies have now disclosed that such victims, outwardly healthy, actually have hidden lymphatic pathology and kidney damages as well. The symptomatic form of infection is most often characterized by the presence in the blood of thousands or millions of larval parasites (microfilariae) and adult worms located in the lymphatic system.
The worst symptoms of the chronic disease generally appear in adults and in men more often than in women. In endemic communities, some 10-50% of men suffer from genital damage, especially hydrocoele (fluid-filled balloon like enlargement of the sacs around the testes) and elephantiasis of the penis and scrotum. Elephantiasis of the entire leg, the entire arm, the vulva, or the breast swelling up to several times normal size-can affect up to 10% of men and women in these communities.
Acute episodes of local inflammation involving skin, lymph nodes and lymphatic vessels often accompany the chronic lymphoedema or elephantiasis. Some of these are caused by the body’s immune response to the parasite, but most are the result of bacterial infection of skin where normal defenses have been partially lost due to underlying lymphatic damage. Careful cleansing can be extremely helpful in healing the infected surface areas and in both slowing and even more remarkably, reversing much of the overt damage that has occurred already.
Lymohoedema may develop within six months and elephantiasis as quickly as a year after arrival.
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| Diagnosis |
Until very recently, diagnosing lymphatic filariasis had been extremely difficult, since parasites had to be detected microscopically in the blood, and in most parts of the world, the parasites have a nocturnal periodicity that restricts their appearance in the blood to only hours around midnight. The new development of a very sensitive, very specific simple "card test" to detect circulating parasite antigens without the need for laboratory facilities and using only finger-prick blood droplets taken anytime of the day has completely transformed the approach to diagnosis. With this and other new diagnostic tools, it will now be possible both to improve our understanding of where the infection actually occurs and to monitor more easily the effectiveness of treatment and control programmes.
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| The goal |
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The primary goal of treating the affected community is to eliminate microfilariae from the blood of infected individuals so that transmission of the infection by the mosquito can be interrupted. This treatment is to protect the next generation from elephantiasis and other manifestations of filarial disease by breaking the cycle of infection between mosquitoes and humans.
The drugs given during the elimination programme will spare the next generation from elephantiasis, hydrocoele and other manifestations of lymphatic filariasis. As an added benefit of the treatment, the burden of intestinal parasites will also be significantly reduced in areas where these exist alongside lymphatic filariasis. Thus, children will grow up healthier, learn more effectively and play a more active role in the development of their communities and countries. [Top]
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| The strategy |
| The programme to eliminate lymphatic filariasis has two major objectives: |
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To stop the spread of filarial infection (i.e. interrupt transmission) in all endemic countries: To interrupt transmission, community wide ("mass treatment") programmes implemented to treat the entire at risk population. In most countries, the programme will be based on once yearly administration of single dosed of two drugs given together: albendaozole plus diethylcarbamazine (DEC), single dose treatment must be carried out for 4-6 years. |
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To alleviate and prevent the suffering and disability of affected individuals (i.e. control morbidity):
-Home based care for patients with elephantiasis and adenolymphangitis (ADL)
-Early surgery for patients with hydrocoele.
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To address the physical, social and economic hardship in individuals who already have clinical manifestations of the disease ((lymphoedema, hydrocoele, elephantiasis of the limbs or genitals, or secondary infections associated with damaged lymphatics), simple, effective hygiene measures are advocated. These are dramatically effective on preventing painful, debilitating and damaging episodes of lymphangitis and can even reverse much of the damage already sustained. They consist of regular washing with soap and water, regular exercising of the limbs and other simple activities easily carried out in the home. [Top] |
| Mass Drug Administration |
Mass Drug administration is focused on community-based treatment, in order to eliminate hidden infections. In community wide treatment, the entire population of an area is treated.
This elimination programme will be based on once yearly administration of two single dose drugs given together.diethylcarbamazine (DEC) plus Albendazole. This yearly, single dose treatment will be carried out for 4-6 years, until the adult worms in the body have come to the end of their normal life span. [Top] |
| Drugs |
Diethylcarbamazine (DEC): developed over 50 years ago, DEC is inexpensive, safe and effective.
Albendazole: This is one of the most widely used antiparasite drugs for curing hookworms. If DEC is given in combination with Albendazole, effectiveness is greatly increased and transmission can be dramatically interrupted.
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Adverse reactions |
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DEC and Albendazole are safe and well tolerated drugs. They kill adult worms in infected patients. Adverse reactions sometimes occur, primarily as a result of the worms being killed by the drugs. General adverse reactions occur during the treatment and generally do not last more than 3 days. These are usually self-limited. The greater the microfilarial load in the patient, the greater the frequency and severity of such reactions: |
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| General adverse reactions |
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headache |
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body ache |
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fever |
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dizziness |
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decreased appetite |
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malaise |
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nausea |
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itching |
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vomiting |
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The additional benefit
An additional benefit of these medications is their effectiveness against each other, well-trenched topical diseases, such an intestinal worms. As an added benefit, the drugs used have a very broad effect against other parasitic infections, especially intestinal parasites, which are a particular burden to children in areas where these exist alongside lymphatic filariasis.
Both Albendazole and DEC have been shown to be effective in killing the adult stage filarial parasites. It is clear that this anti parasite treatment can result in improvement of patients elephantiasis and hydrocoele (especially in the early stages of disease), but the most significant treatment advance to alleviate the suffering of those with elephantiasis has come from recognizing that much of the progression in pathology results from bacterial and tissue with compromised lymphatic function caused by earlier filarial infection.
Thus, rigorous hygiene to the affected limbs, with accompanying adjunctive measures to minimize infection and promote lymph flow, results both in a dramatic reduction in frequency of acute episodes of inflammation ("filarial fevers") and in an astonishing degree of improvement of the elephantiasis itself. [Top] |
| Economic and social impact |
Lymphatic filariasis is a major social economic burden. Lymphatic filariasis is a disfiguring, disabling disease, which makes life difficult for you and your family. The physical consequences are pain, ugly swelling limbs and bad smelling skin. But there is also damage to the inside of the body that you can’t see: the lymphatic system and the kidneys are affected. Everyday life becomes difficult. Simple actions like walking and working become impossible. The more the disease progresses the more sufferers are shunned by society.
Because of its prevalence often in remote rural areas, on the one hand, and in disfavored periurban and urban areas, on the other, lymphatic filariasis is primarily a disease of the poor. As many filariasis patients are physically incapacitated, it is also a disease that prevents patients from having a normal working life. LF exerts a heavy social burden that is especially severe because of the specific attributes of the disease, particularly since chronic complications are often hidden and are considered shameful. For men genital damage is severe handing leading to physical limitations and social stigmatization. For women, shame and taboos are also associated with the disease. When affected by lymphoedema, they are considered undesirable and when their lower limbs and genital parts are enlarged, they are severely stigmatized: marriage, in many situations and essential source of security, is often impossible. It’s clinical signs result not only in physical but also in psychological damage. To fight to eliminate LF is also a fight against poverty. [Top] |
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