Table 1 Possible challenges to implement multiple ivermectin treatments annually

Increased cost

- Reticence from drug manufacturers to provide additional huge quantities of ivermectin for free.

- Increased local cost for ivermectin distribution, because of more logistical needs and multiplied labour force.

Multiple CDTI per year would increase absolute cost, but the public health benefits for both malaria and neglected tropical diseases would be huge.

- Secure external funding to sustain pluri-annual CDTI.

- Convince drug manufacturers to continue providing the drug for free.

Reduced compliance

- Fear of side effects.

- Ignorance, lack of education and sensitization about CDTI.

Most adverse effects of ivermectin are due to an initially high microfilarial density or loasis co-infection. Rarely, adverse effects may still occur outside these circumstances but often requires abnormally high drug dosages and/or frequency of administration.

- Use a test-and-not-treat approach in co-endemic settings [16].

- Respect dosages of 150–200 μg/kg.

- Educate the population on the health benefits of CDTI.

- Reassure the population that side effects will decrease with subsequent doses of ivermectin, as the microfilarial density keeps reducing.

Drug resistance

Increased exposure to ivermectin due to a higher frequency of treatment may induce ivermectin resistance in the parasite [17].

Polytherapy could help prevent drug resistance to a single drug. During the RIMDAMAL study for instance, ivermectin was co-administered with albendazole.

- Monitor drug resistance.

- Provide ivermectin in combination with other drugs using an integrated MDA approach [18].

Drug interactions

Ivermectin can interact with a number of molecules, including anti-infectious agents [19].

Important for drugs that are taken regularly, such as anti-epileptic drugs or antiretroviral drugs.

Individuals presenting a risk for drug interactions should not receive a multi-dose ivermectin treatment regimen.