Filariasis Treatment & Management

Updated: Oct 09, 2017
  • Author: Brian F Lich, MD; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Treatment

Approach Considerations

Medical Management

The medical management of a filarial infection should be specific and based on the microfilariae isolated or antigenemia detected. Specific attention should be paid to the presence of coinfection with multiple filarial organisms, as this will alter the treatment regimen.

Mass drug administration (MDA) reduces the transmission of filarial infection and disease morbidity by decreasing the burden of microfilaremia, resulting in suboptimal levels for transmission by disease vectors. [48, 49, 50, 51, 52, 53] The effects of mass treatment on filariasis have reportedly been sustained for up to 6 years. [54, 55, 56, 57]

In 1997, the World Health Organization (WHO) initiated the Global Program to Eliminate Lymphatic Filariasis (GPELF) with a goal to globally eliminate lymphatic filariasis as a public health problem by 2020. [2, 30] This initiative utilizes mass drug administration (MDA) in 60 countries at risk to reduce prevalence levels to a point at which transmission is no longer sustainable. The effort has led to a prevalence reduction in 15 countries thus far. [2] Overall, MDA strategies have differed both in their drug regimen and frequency. Traditionally, annual mass treatment with albendazole plus ivermectin or DEC has been used to interrupt the transmission of W bancrofti.

One study evaluated the effect of higher dose and increased frequency (twice yearly) of albendazole plus ivermectin therapy for W bancrofti. It found that it resulted in complete microfilarial clearance, as well as a more sustained clearance than that resulting from standard-dose albendazole-ivermectin treatment. [58] Another study demonstrated that a 3-drug regimen (DEC, albendazole, ivermectin) resulted in better outcomes and fewer adverse events than therapy with DEC and albendazole alone. [59]

In 2016, Abu-Hamed, Sudan, became the first focus of onchocerciasis to eliminate the disease under a mass treatment program with ivermectin. [33] Today, continued efforts to reduce disease prevalence are conducted via guidance by the WHO and Nongovernmental Development Organizations Coordination Group for Onchocerciasis Control.

Loiasis remains of particular interest when initiating MDA programs for lymphatic filariasis, because the drugs commonly used in these regimens (DEC) may have adverse effects in patients with significant loiasis.

Although there have been efforts to develop an effective vaccine, none is currently available. [60]

Surgery

Lymphatic filariasis

Large hydroceles and scrotal elephantiasis can be managed with surgical excision. Correcting gross limb elephantiasis with surgery is less successful and may necessitate multiple procedures and skin grafting.

Onchocerciasis

Nodulectomy with local anesthetic is a common treatment to reduce skin and eye complications.

Diet and activity

Fatty foods are restricted in individuals with proven chyluria that is associated with lymphatic filariasis. Because of associated nutritional deficiencies, diets should be high in protein.

Individuals with chronic lymphatic filariasis are encouraged to mobilize (with compression bandage support and regular exercise) the affected limb and to elevate it at night.

Prevention

Avoidance of bites from insect vectors is usually not feasible for residents of endemic areas, but visitors to these regions should use insect repellent and mosquito nets. As noted above, mass drug administration programs are the backbone of the goal to reduce prevalence rates to a point at which transmission is no longer sustainable.

Consultations

To prevent inappropriate treatment, consult an infectious disease specialist in all cases of suspected filariasis outside of endemic nations. Other possible consultations include:

  • Urologist
  • Ophthalmologist
  • General surgeon
  • Plastic surgeon
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Pharmacologic Therapy

Lymphatic filariasis

Diethylcarbamazine (DEC) is the treatment of choice for lymphatic filariasis. However, when co-infection with other filarial organisms exists or in the context of mass drug administration, the treatment course must be adjusted accordingly.

Treatment for lymphatic filariasis monoinfection consists of DEC 6 mg/kg for 12 days. Alternatively, doxycycline (200 mg/d) may be added to the regimen for a 6-week course. Studies indicate reduced severity of lymphedema in certain cases. [61] Other regimens, including doxycycline for 23 days followed by doxycycline plus albendazole for 7 days, have also been shown to be safe and effective. [62] As stated above, in the context of MDA to reduce microfilaremia in endemic areas, annual (or semi-annual) multidrug regimens of albendazole plus ivermectin or DEC are used.

Patients with asymptomatic microfilaremia can be treated on an outpatient basis. Supervision of oral DEC therapy and post-administration observation are recommended for patient compliance with therapy and for the management of febrile reactions in heavily infected patients.

Inpatient care may initially be required for adenolymphangitis (ADL) and chronic filariasis. Such care includes the use of antihistamines, steroids, pain relief, and intravenous antibiotics for secondary infections.

Lymphedema

Steroids can be used to soften and reduce the swelling of lymphedematous tissues. As noted above, mild to moderate filarial lymphedema has been shown to improve with a 6-week course of doxycycline, independent of ongoing infection. [61]

Bed rest, limb elevation, and compression bandages traditionally have been used for the management of chronic lymphedema.

Chronic filariasis

Treatment of chronic filariasis does not change the prognosis, as irreversible fibrosis usually destroys lymphatic tissue. However, asymptomatic patients, hoping to diminish progression of the disease, still typically undergo treatment, although the benefit of this is unclear. [63]

Chyluria

In the treatment of chyluria, a special low-fat, high-protein diet supplemented with medium-chain triglycerides may prove beneficial.

Secondary infection

Supportive care should include the prevention of secondary infection, especially in patients with advanced disease. Individuals with chronic infections should wash the affected area frequently, apply antiseptic creams to abrasions, wear comfortable footwear, and exercise the affected limb to aid lymphatic flow.

Concomitant infections

The treatment regimen must be adjusted in patients who are co-infected with onchocerciasis and/or loiasis to avoid a severe adverse reaction to DEC.

For concomitant infection with onchocerciasis, DEC cannot be used as primary treatment owing to the risk of complications resulting from dying microfilariae in the eye or skin. To avoid this, co-infected patients can be treated first with ivermectin followed by DEC treatment one month later. However, when there is ocular involvement, this timing mechanism remains unclear. [64] Alternatively, doxycycline 200 mg/d for 6 weeks may be given first, followed by a single dose of ivermectin 150 mcg/kg; however, these studies were solely evaluated in onchocerciasis and did not focus on individuals co-infected with lymphatic filariasis. [65]

For concomitant infection with loiasis, treatment variation depends on the level of Loa loa microfilariae in the blood. In general, if microfilarial levels of Loa loa are low (<2500/mL), DEC can be safely administered with low risk for serious adverse reactions. One study indicated that ivermectin could safely be used until Loa loa levels reached 8000 microfilariae/mL, at which point the threshold for a severe reaction to ivermectin significantly increased. [66] If levels exceed 8000 microfilariae/mL, pretreatment with albendazole 200 mg bid for 3 weeks has shown potential benefit in its ability to decrease microfilarial levels in loiasis. [67]

Onchocerciasis

The primary treatment of onchocerciasis depends on the prevalence and transmission of the disease in the area. In areas with high transmission rates, ivermectin is administered at a dose of 150 mcg/kg once every 3 months until symptoms resolve. [68] . In nonendemic areas, the same treatment regimen as above with ivermectin may be used; however, some regimens that include doxycycline 200 mg/d for 4-6 weeks followed by ivermectin have been investigated. [69]

Moxidectin is being investigated as an alternative to ivermectin for the treatment of river blindness. This agent may shorten the number of annual treatments to six. [70]

Loiasis

In general, DEC is used as the primary treatment for loiasis; however, owing to the risk of severe encephalopathy in patients with significant microfilaremia, the regimen is adjusted accordingly. Thus, before starting therapy, an accurate microfilarial count must be obtained.

If a patient has a low level of microfilariae in the blood (<2500/mL), he or she can be safely treated with DEC 8-10 mg/kg/d for 21 days. If microfilarial levels are higher, patients should be treated only if they are symptomatic. In these cases of high microfilarial levels and symptoms, patients can be pretreated with albendazole 200 mg bid for 3 weeks prior to definitive treatment with DEC. [67] When available, apheresis lowers microfilarial counts prior to treatment with DEC. [71]

Mansonella infection

Treatment strategies for M perstans infection vary based on regional strain differences. Several treatment courses may be needed to achieve cure. Wolbachia, an endosymbiont found in many filarial species, will predict whether doxycycline is necessary to clear microfilaremia. [72] For strains that do not contain Wolbachia, treatment with DEC and mebendazole or mebendazole alone may be effective, although rates of microfilarial clearance are low.

Doxycycline treatment typically kills or sterilizes the filarial nematode. In an open-label, randomized trial, Coulibaly et al recruited patients with M perstans infection from four African villages in Mali. Patients were randomly assigned to receive 200 mg of doxycycline orally every day for 6 weeks or no treatment. At 12 months, 97% of patients who received doxycycline had no detectable blood levels of M perstans, compared with 16% of patients in the group who did not receive treatment. At 36 months, M perstans remained suppressed in 75% of patients who had received doxycycline. [73]

M ozzardi may be treated with ivermectin while DEC is commonly used for M streptocerca. Ivermectin has been used to treat these infections and those strains of M ozzardi that contain Wolbachia may respond to doxycycline. M ozzardi strains do not respond to DEC treatment.

Long-Term Monitoring

Patient monitoring includes posttreatment follow-up for 12 months, with examination of peripheral blood and skin snips for microfilariae.

Observe and monitor oral therapeutic plans with DEC because compliance with therapy is poor and usually incomplete.

Patients with filariasis are, by default, at risk for other parasitic infections, because areas endemic for bancroftian filariasis are also endemic for other parasites. After treatment, patients should be monitored for symptoms that are characteristic of parasitic infections.

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