Prevention and Treatment
Vector Control
The idea behind vector control is to eliminate the intermediate host by killing the fly larvae.  This disrupts the transmission of the disease by eliminating the parasite reservoir and therefore the incidence in the human population declines.  One method of controlling the Simulium Black Fly (used by the OCP) is to use helicopters to aerially apply larvicide into the rivers and nearby breeding habitats of the fly.  This method has had no lasting effect in Central America because the campaigns have been too short and directed at areas that were too small, but has reduced transmission in Africa.  A major problem with this method of control on both continents is locating and treating all breeding grounds because some species of Simuliid breed in streams only 50 cm wide.  If even a small number of flies remain in an endemic area, this vector control is not effective at eliminating transmission.  In the past, health officials have also tried spraying DDT in rivers and fogging areas with dieldrin, but these methods were ineffective and had severe environmental consequences.  In general, vector control has been more effective in the broad endemic areas in Africa, than in Latin America where the disease is distributed in small foci. (23, 24)
 
(21)
(22)
 

Personal Protection
Because no vaccine or effective chemoprophylaxis is available to prevent onchocerciasis, one method used to reduce the chance of infection is to take basic measures to avoid getting bitten by the black fly.  These measures include avoiding the black fly habitat, using insecticides like DEET, wearing long pants and sleeves, and putting insect netting around where one sleeps.  These methods have been found to be fairly effective for travelers, but less effective for people who live in endemic areas. (25)

(26)
 


Ivermectin (Mectizan, Stromectol)
This is the drug of choice for treating onchocherciasis.  It is a semisynthetic braod-spectrum anthelmintic drug that was isolated from S. avermitilis by Merck.  It affects the parasite by binding selectively with glutamate-gated chloride-ion channels in invertebrate nerve and muscle cells.  This causes cell death in the microfilariae once the drug has been metabolized by the liver, but does not kill the adult worms.  In mass treatment programs like the APOC, a single dose can be given once a year and will reduce microfilariae to low levels for up to 2 years.  If an individual needs more intensive therapy, he or she may receive doses every three months.
* Risks: This is the safest drug available to treat the parasite, but it has been documented to have adverse effects in some populations. 

  Patients with Sowda (a severe form of dermatitis first described in Yemen) are more likely to have severe reactions including edema and aggravation of onchodermatitis.  The drug has also not been proven safe for pregnant women or women who are breastfeeding.  In areas where Loa loa is coendemic, Ivermectin is not recommended because of the risk of encephalitis.  About 1-5% of patients taking Ivermectin experience adverse effects. (14) (27)
 

Suramin (Metaret or Antrypol)
This drug was originally developed as an antiparasitic drug to treat CNS trypanosomiasis.  It is the only drug available that is effective in killing the adult worms.  Due to side effects, a test dose of 100-200 mg is usually given.  Short term side effects include nausea, vomiting, shock, loss of consciousness, and skin reactions.  If the patient’s reaction is not severe, he or she is given 66.7 mg/kg total dose in 6 weekly installments through a slow IV injection.  Over this period, many patients experience delayed effects including skin eruptions, fever, paresthesia, and hematuria.  Because of the difficulty in using an IV medication in public health initiatives and the numerous side effects, Suramin has largely been replaced by Ivermectin in onchocerciasis treatment.  Suramin is now only used in extreme cases of hyperreactive onchodermatitis.(14, 17)

 

DEC
This anthelmintic drug was used as a microfilaricide before the invention of Ivermectin.  It was taken as an oral dose and often provoked the severe Mazzotti reaction.  The severity of the effects (itching, rash, headache, fever, joint pain, swollen lymph nodes, vertigo) varies from person to person.  There can also be severe ocular effects due to the mobilization of the microfilariae.  The acute side effects and the availability of free Ivermectin have led to a discontinuation of using DEC for onchocerciasis treatment. (17)

Nodulectomy
This method of treatment is not feasible as a population-wide intervention due to the high cost of surgery and the unavailability of trained doctors.  The only case of systemic use occurred in endemic areas of Guatemala and Mexico.  Nodules around the head were particularly targeted to reduce the microfilarial load near the eyes.  This treatment could be a beneficial addition to patients already being treated with Ivermectin. (14)