Dr Ayesha Akinkugbe, Consultant Dermatologist and Genitourinary Doctor at Lagos University Hospital, Idi-Araba, Lagos, talks to ALEXANDER OKERE about elephantiasis, a common but neglected tropical disease in Nigeria
What is elephantiasis?
Elephantiasis, also known as lymphatic filariasis and considered a neglected tropical disease worldwide, is a parasitic disease caused by microscopic thread-like worms. Adult worms only live in the human lymphatic system. The lymphatic system maintains the body’s water balance and fights infections. Lymphatic filariasis is spread from person to person by mosquitoes. People with the disease can have lymphedema and elephantiasis, and in men, swelling of the scrotum called a hydrocele. Lymphatic filariasis is one of the leading causes of permanent disability around the world. People affected by this disability are generally stigmatized in communities with the associated job loss and economic downturn.
Mosquitoes of the genera Aedes, anopheles, culex or mansonia are intermediate hosts and vectors of all the species responsible for lymphatic filariasis. It is most common in sub-Saharan Africa, Southeast Asia, the Indian subcontinent, the Pacific islands, and the tropical and subtropical climates of the Caribbean and South America. Most of the patients in endemic areas were exposed in their 30s or 40s.
Why is it considered a neglected tropical disease?
Neglected tropical diseases include several diseases that have a range of effects, from extreme pain to permanent disability to death. NTDs are infectious diseases that mainly affect the poorest people in the world. They have been neglected for decades, initially as part of a general disregard for the developing world, and more recently because of the intensity of attention paid to HIV / AIDS, tuberculosis and malaria.
What are the risk factors?
A relatively prolonged stay in an endemic area is usually necessary to contract the infection while disorganized urbanization increases the vector population and, consequently, the increase in the incidence and prevalence of these diseases in the regions. low income countries. Repeated mosquito bites over several months or years are necessary to contract lymphatic filariasis.
In addition, people who have lived for a long time in tropical or subtropical areas where the disease is common are most at risk of infection. Short-term tourists have a very low risk, although infection can appear during a blood test.
How exactly does the infection occur?
The main reservoir of filariasis is humans and the vector is mosquitoes. Human-to-human transmission occurs through mosquito bites. Mosquitoes deposit larvae in a human’s skin, which burrow through the bite wound into the bloodstream. The larvae migrate to regional lymph nodes and lymphatics and become adults. Adult worms undergo sexual reproduction, with females giving rise to microfilariae which actively migrate through lymph and blood.
A mosquito ingests the microfilariae during a blood meal. After ingestion, the microfilariae pass through the wall of the mosquito’s midgut and reach the chest muscles. Within the mosquito, the microfilariae turn into infectious larvae and migrate to the mosquito’s proboscis, where they can infect a human during the mosquito’s next blood meal.
When does it become a disease?
After mating, the adult female lays thousands of microfilariae daily. In most areas, the microfilariae of W. bancrofti are circulating (present in the bloodstream) during the night hours. In the South Pacific, microfilariae circulate throughout the day. Filaria antigens trigger increased cytokines and immunoglobulins Molting, death or death of adult worms produces pathological changes while chronic and repeated infections lead to granuloma formation, fibrosis of lymphatic vessels and surrounding connective tissue.
The effects are contractile dysfunction and lymphatic occlusion, causing lymphedema and inhibiting lymphatic drainage, and susceptibility of the human host to bacterial and fungal infections, which further contribute to tissue damage.
How long can the worm survive in the human body?
Adult heartworms can survive inside humans for up to nine years. Adult worms also carry Wolbachia (endosymbiotic bacteria) in their gut, which appears to be beneficial for worms.
Which regions of the country are the most affected?
In sub-Saharan Africa, around 512 million people are at risk of becoming infected, while 28 million are known to be infected. Although mortality from lymphatic filariasis is low, the disease is the fourth leading cause of disability-adjusted life years. Nigeria is ranked third most endemic country in the world. Lymphatic filariasis remains a public health problem in Nigeria, being endemic in 583 (75.3%) of the 774 local government areas.
In Nigeria lymphatic filariasis is widespread and constitutes a serious public health problem. It occurs in all six geopolitical zones, however, the highest prevalence is found in the Northwest. The high prevalence in the northwest is largely attributed to unfavorable climatic conditions which have set up man-made options such as building irrigation, further enhancing disease vectors to thrive.
Why is it difficult for people to know when they are infected?
Symptoms can take anywhere from nine months to a year to appear after the initial infection. Children or individuals in endemic areas often remain asymptomatic, while others exhibit acute and / or chronic signs and symptoms. Lymphatic filariasis is known to cause a wide range of clinical and subclinical symptoms. It is estimated that two-thirds of those infected have no clear evidence of the disease, but when tested, they showed some level of immunosuppression.
Since the disease is transmitted by mosquitoes, which are widespread in our society, how do you know when you have been bitten by a mosquito carrying the malaria parasite and one carrying the parasitic worms responsible for lymphatic filariasis?
You may not immediately know the difference, and it is also difficult for a doctor to tell the difference. However, if one has a bite and it does not seem to heal well, and even more so if one is in an endemic area, a strong suspicion of elephantiasis is necessary and best treated in the first place. This is why there is a call for increased awareness, prevention of mosquito bites and mass treatment of communities.
When should an infected person come for an assessment?
It is advisable to present yourself immediately to avoid complications.
How to make a diagnosis and what should a doctor watch out for?
Several tests can be carried out, some more easily than others while some are not carried out in certain places. The standard method for diagnosing an active infection is examining the blood under a microscope to identify microscopic worms, called microfilariae. This is not always feasible because, in most parts of the world, microfilariae are nocturnal periodic, which means that they circulate in the blood only at night. For this reason, the blood sample should be taken at night to coincide with the appearance of microfilariae in the blood.
Serological techniques offer an alternative to microscopic detection of microfilariae for the diagnosis of lymphatic filariasis. Because lymphedema (swelling of the arm or leg) can develop several years after infection, lab tests are often negative in these patients.
Laboratory tests include a smear of peripheral blood (thick and thin smears) taken between 10 p.m. and 2 a.m. because microfilaria have nocturnal periodicity and Giemsa or Wright spots. Circulating filaria antigen (W. bancrofti) detects antigens from adult filaria and can be positive even in those without microfilaria. There are anti-filarial antibody tests for high levels of anti-filarial IgG4 in the blood. They are mainly used for travelers who do not come from endemic areas.
Others are the polymerase chain reaction for the detection of antigens, used in research, and biopsy, using tissue from skin lesions. In areas endemic to onchocerciasis (river blindness) caused by onchocerca volvulus or loiasis, also known as the African eye worm caused by the parasitic worm called Loa loa, co-infection should be determined, as management will be different. Ultrasound shows adult worms moving through lymphatic vessels; the “wire dance sign” – an irregular pattern of movement of the worms – can be detected on Doppler. Lymphoscintigraphy, which assesses lymphatic drainage and detects preclinical lymphedema; and chest x-ray.
Is elephantiasis curable?
Yes, it is curable when detected early; however, it is rare. Most cases are detected late. In chronic lymphangitis and lymphedema, healing can be difficult because the lymph vessels are damaged. However, surgery can help.
In what ways can it be treated?
There are four main treatment methods available. This is an anthelmintic treatment, antibiotic therapy (against the symbiotic bacteria Wolbachia), surgical excision or decompression, needle aspiration. But severely damaged extremities can undergo surgical decompression of the lymphatic system.
Are there any habits that could prevent elephantiasis?
Yes. The best way to prevent elephantiasis is to avoid mosquito bites. At night, sleep in an air-conditioned room or sleep under a mosquito net. Between dusk and dawn, wear long sleeves and pants, and use mosquito repellent on exposed skin. Another prevention approach is giving entire communities drugs that kill microscopic worms and controlling mosquitoes. Annual mass treatment reduces the level of microfilariae in the blood and thus decreases the transmission of infection. It is the basis of the World Health Organization’s Global Lymphatic Filariasis Elimination Program.
What are the complications of the disease?
Complications of the disease include chronic lymphedema, pain, recurrent skin infections, hydrocele, renal involvement (chyluria, hematuria, proteinuria), tropical pulmonary eosinophilia, immobility and disability. There are also socio-economic implications.
Are there some mistaken beliefs, such as witchcraft, curses, and other superstitions, that make cases of elephantiasis worse in Nigeria?
Absoutely! There is a lack of awareness of the condition. It is also believed to be a spiritual problem, a condition among those with poor hygiene. This results in stigma, discrimination against an infected person and social exclusion.
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