Summary about Disease
Lymphatic filariasis (LF), commonly known as elephantiasis, is a neglected tropical disease caused by parasitic worms called filariae. These worms are transmitted to humans through mosquito bites. The infection damages the lymphatic system, which can lead to abnormal enlargement of body parts, causing pain, severe disability, and social stigma.
Symptoms
Many people with lymphatic filariasis are asymptomatic, meaning they show no outward signs of infection. However, even without visible symptoms, the parasites damage the lymphatic system. When symptoms do appear, they can include:
Lymphedema: Swelling of the limbs (arms, legs), genitalia (hydrocele in men), or breasts.
Elephantiasis: Thickening and hardening of the skin, often in the legs and scrotum. This is a severe form of lymphedema.
Acute Adenolymphangitis (ADL) attacks: Episodes of fever, pain, and inflammation in the affected limbs.
Tropical Pulmonary Eosinophilia (TPE): A rare manifestation characterized by cough, shortness of breath, and increased eosinophils in the blood.
Causes
Lymphatic filariasis is caused by three species of thread-like filarial worms:
Wuchereria bancrofti (responsible for 90% of cases)
Brugia malayi
Brugia timori The worms are transmitted to humans through the bites of infected mosquitoes (various species, including *Culex, Anopheles*, and *Aedes*). When an infected mosquito bites a person, the infective larvae (microfilariae) are deposited on the skin and enter the body through the bite wound. The larvae migrate to the lymphatic vessels, where they mature into adult worms. Adult worms live for several years and produce millions of microfilariae, which circulate in the bloodstream and can be ingested by mosquitoes during a blood meal, continuing the cycle of transmission.
Medicine Used
The primary medicines used to treat lymphatic filariasis are:
Diethylcarbamazine (DEC): DEC kills the microfilariae in the bloodstream. It is the mainstay of mass drug administration (MDA) programs aimed at eliminating the disease.
Albendazole: Albendazole is often given in combination with DEC or ivermectin. It has some effect on the adult worms.
Ivermectin: Ivermectin is used in combination with albendazole in areas where onchocerciasis (river blindness) is co-endemic. It primarily targets the microfilariae. Important: These medications should only be taken under the supervision of a healthcare professional. Side effects are possible.
Is Communicable
Yes, lymphatic filariasis is communicable, but it is not directly transmitted from person to person. It is transmitted through the bite of infected mosquitoes that have picked up microfilariae from an infected person. Therefore, it is considered vector-borne.
Precautions
Precautions to prevent lymphatic filariasis include:
Mosquito bite prevention:
Use mosquito repellent containing DEET, picaridin, or oil of lemon eucalyptus.
Wear long-sleeved shirts and pants, especially during dawn and dusk when mosquitoes are most active.
Use mosquito nets (preferably insecticide-treated nets) while sleeping.
Install screens on windows and doors.
Mosquito control:
Eliminate mosquito breeding sites by draining standing water in containers, such as tires, buckets, and flower pots.
Apply insecticides to mosquito breeding sites when appropriate.
Mass Drug Administration (MDA): Participate in MDA programs in endemic areas, where available.
Good Hygiene: Maintain good hygiene to prevent secondary bacterial infections in affected limbs.
How long does an outbreak last?
Lymphatic filariasis does not typically occur in outbreaks in the same way as some other infectious diseases like influenza. Because it requires multiple mosquito bites over an extended period to establish an infection, and the adult worms can live for several years, the disease is more of an endemic problem in affected areas rather than something that presents in short-term outbreaks. The effects of lymphatic filariasis can persist for a lifetime if left untreated.
How is it diagnosed?
Lymphatic filariasis is diagnosed through:
Microscopic examination: Identification of microfilariae in blood samples. Blood samples are typically collected at night when microfilariae are most abundant in the peripheral circulation.
Antigen detection tests: Immunochromatographic card tests (ICT) and enzyme-linked immunosorbent assays (ELISA) detect filarial antigens in the blood. These tests can detect infection even when microfilariae are not present.
Ultrasound: Ultrasound can sometimes be used to visualize adult worms in lymphatic vessels.
Lymphoscintigraphy: A nuclear medicine imaging technique to assess lymphatic function. This is not routinely used for diagnosis.
Timeline of Symptoms
The timeline of symptoms can vary greatly. Here's a general overview:
Initial infection: Often asymptomatic for years.
Subclinical damage: Damage to the lymphatic system may occur without noticeable symptoms.
Early symptoms:
Acute adenolymphangitis (ADL) attacks (recurring episodes of fever, pain, and inflammation).
Swelling that may be temporary and resolve with rest.
Chronic symptoms:
Lymphedema (persistent swelling of limbs, genitalia, or breasts).
Elephantiasis (thickening and hardening of the skin) - develops over many years.
Increased susceptibility to secondary bacterial and fungal infections of the skin and lymphatic system.
Important Considerations
Global Elimination Program: The World Health Organization (WHO) has a program to eliminate lymphatic filariasis as a public health problem through mass drug administration (MDA).
Morbidity Management and Disability Prevention (MMDP): Even after parasite elimination, ongoing care is needed to manage the morbidity associated with lymphedema and elephantiasis, including hygiene, skin care, exercise, and psychosocial support.
Co-endemicity: In regions where LF co-exists with other filarial diseases (like onchocerciasis), treatment strategies must be carefully considered to avoid severe adverse reactions.
Stigma: Lymphatic filariasis can lead to significant social stigma. Education and support are crucial for affected individuals and communities.
Secondary Infections: Individuals with lymphedema are at increased risk for secondary bacterial and fungal infections. These infections should be promptly treated.