Open the West Africa carton, not a feed
The US label's onchocerciasis indication is not a vibe. It cites randomised, double-blind, placebo-controlled and comparative studies in 1427 patients from endemic West Africa.
Diethylcarbamazine citrate was the old comparator in the comparative arms. DEC-C could crash microfilariae too, and it was infamous for Mazzotti-type and ocular reactions when larvae died in a rush. Ivermectin's job in those cartons was to show a single oral dose could cut skin counts hard, keep them down for months, and do it with a reaction profile programmes could live with. The evaluation block the label still quotes rests on 1278 patients. That is the carton this page opens. A feed that starts with a pandemic headline is a different drawer, and it does not get to speak first on an Edinburgh trial desk.
Onchocerca volvulus adults sit in subcutaneous nodules for years. The tablet is microfilaricidal. It is not a sterilising adulticide. Every positive curve in this file has to be read with that limit or you will mis-file a year of low skin counts as a cure. Nodules can be excised; the label even mentions nodulectomy as a way to remove the factory. Mass programmes did not scale surgery. They scaled a 3 mg chip and a calendar. If you want the calendar, use the working card. If you want the numbers that justified the calendar, stay here.
Liberia 200: three mcg/kg rungs, one pick
| Rung | What the Liberia file showed | Flag for the desk |
|---|---|---|
| 100 mcg/kg | Big drop, fewer people fully clear at 3 months | Under-clears versus 150/200 |
| 150 mcg/kg | Clearance like 200, milder systemic reaction than 200 | Picked as initial optimum |
| 200 mcg/kg | Similar 3-month kill, more systemic reaction | Not the onchocerciasis default |
| Placebo | No comparable crash in skin counts | Control arm, not a treatment |
A controlled dose-finding study in 200 Liberians compared 100, 150, and 200 mcg/kg against placebo and followed people for 12 months. Therapy was associated with only minimal systemic and ocular side effects in that design. The 200 mcg/kg rung carried more systemic reaction than 100. Each ivermectin arm cut skin microfilariae by day 3 and by about 95 percent at three months. At three months, the share of people with no microfilariae in a skin specimen was significantly lower in the 100 mcg/kg group than in the 150 or 200 groups. At twelve months, skin levels were still down about 80 percent. Ocular involvement fell in all treated groups.
The authors' practical post, and the one programmes later lived with, was that 150 mcg/kg looked like the optimal initial dose: enough clearance that 100 could not match at three months, without paying the extra systemic reaction seen at 200. That is a trial signal, not a marketing preference. It is also why this site's SERP lock for onchocerciasis talks 150 mcg/kg and a 3 mg chip count, while strongyloidiasis - a different parasite, a different endpoint - sits near 200. Mixing the rungs is how a working card gets someone the wrong stack of tablets.
83.2 percent by day 3, 99.5 by month 3
DailyMed still prints the geometric-mean skin-snip drops from a double-blind, placebo-controlled adult study of moderate to severe infection.
A single 150 mcg/kg dose produced an 83.2 percent decrease in skin microfilariae count at three days and a 99.5 percent decrease at three months. A marked reduction of more than 90 percent held for up to twelve months after that one dose. That year-long tail is the MDA rationale in one line. You do not need a daily tablet to keep skin counts crushed. You need a counted 3 mg pass and a calendar that comes back before the factory in the nodules restocks the skin.
Eyes have their own curve, and it is easy to misread. As with other microfilaricides, some patients showed an increase in anterior-chamber microfilariae at day 3. By three and six months, a significantly greater share of ivermectin-treated patients had decreases in that anterior-chamber count than placebo patients. A separate open paediatric study in 103 children aged 6 to 13 years, weights 17 to 41 kg, showed similar skin-count drops lasting up to twelve months. The Stromectol DailyMed label is the primary carton for those percentages. This page does not re-dress them as a cure of the adult worm.
DEC-C sits as the old comparator
Before ivermectin, diethylcarbamazine was the microfilaricide people knew, and they knew it as a rough drug in onchocerciasis. Mazzotti reactions - itch, rash, tender nodes, fever, occasional hypotension - and ocular inflammation were part of the DEC-C story because dying larvae dump antigen. The West Africa comparative studies put ivermectin next to that standard rather than next to a rumour. The signal that moved programmes was not 'a new class exists'. It was 'a single oral dose can replace a harsher, more frequently dosed microfilaricide in community use'.
Suramin, an older adulticide, sits in the historical drawer as a toxic hospital drug, not as a mass-campaign tool. CDC's current clinical-care note still says ivermectin is the treatment of choice to kill microfilariae, that it does not kill adult worms, and that suramin and DEC should not be used. Doxycycline, aimed at Wolbachia endosymbionts, is a later specialist sleeve: a six-week course can kill a majority of adult females and sterilise most of the rest, but it does not clear microfilariae on ivermectin's timetable. This trial file mentions that sleeve so nobody files doxycycline as a replacement for the 3 mg onchocerciasis pass. It is an adjunct in selected programmes and clinics, not the carton that earned MDA.
Stool-cure rows belong in a side sleeve
| Carton | n / design (label) | Signal this desk posts |
|---|---|---|
| Onchocerciasis evaluation | 1278 patients; 150 mcg/kg adult study | 83.2% day 3, 99.5% month 3 skin mf |
| Onchocerciasis indication | 1427 West Africa; vs placebo and DEC-C | Single oral dose, programme-usable |
| Liberia dose-finding | 200 people; 100/150/200 vs placebo | 150 mcg/kg picked as initial optimum |
| Paediatric open | 103 ages 6-13; 17-41 kg | Similar skin-count drop to 12 months |
| Strongyloides vs albendazole | Two comparative studies | Higher stool-cure than albendazole |
| Strongyloides vs thiabendazole | US and international | Similar cure, better tolerated |
Strongyloidiasis is on the same US tablet and a different endpoint. Cure meant no larvae in at least two follow-up stools three to four weeks after therapy. Against albendazole 200 mg twice daily for three days, a single 170-200 mcg/kg ivermectin dose cured 24 of 26 (92 percent) versus 12 of 22 (55 percent) in one international comparison, and 126 of 152 (83 percent) versus 67 of 149 (45 percent) in a WHO study. Against thiabendazole 25 mg/kg twice daily for three days, ivermectin was in the same efficacy band and better tolerated. Those rows justify the 200 mcg/kg strongyloidiasis band. They do not outrank the onchocerciasis carton on this page.
A French follow-up in a non-endemic setting, where reinfection was unlikely, saw larvae return in stool as late as day 106. The label's post is operational: at least three stool exams over three months, concentration methods such as Baermann, retreatment if recrudescence appears. Immunocompromised hosts were never given an adequate controlled regimen; two-week intervals and even monthly suppression show up as practical language, not as a tidy trial win. Keep that sleeve labelled. Mixing a stool-cure percentage into an onchocerciasis argument, or the reverse, is how trial files get sloppy.
TOGETHER and ACTIV-6 stay a negative ping
A dish assay can inhibit SARS-CoV-2 at concentrations more than fifty-fold above what a labelled human plasma level can reach. That is a laboratory ping, not a trial signal. When people treated it as a signal, this desk's job was to wait for hospital and recovery endpoints in randomised outpatients. TOGETHER, in Minas Gerais, randomised high-risk outpatients to ivermectin 400 mcg/kg daily for three days or placebo. It did not find a significantly or clinically meaningful lower risk of hospital admission or prolonged emergency-department observation. Secondary outcomes were empty in the same direction. The NEJM TOGETHER report is the carton.
ACTIV-6, a US decentralised platform, tested 400 mcg/kg for three days and later 600 mcg/kg for six days in mild-to-moderate outpatient COVID-19. Time to sustained recovery did not move in a way that mattered. Hospitalisation and death were uncommon and not improved. Duke's summary with Vanderbilt was blunt: no role for ivermectin in that setting given other options that actually cut hospitalisation and death. This page flags those arms so an onchocerciasis file cannot be laundered into a viral one. The 3 mg chip earned its reputation on skin snips. It did not earn a respiratory indication. FDA language matches that flag.
Mazzotti percentages are dying-larva noise
In 963 adults treated with 100 to 200 mcg/kg, worsening Mazzotti features in the first four days included pruritus 27.5 percent, fever 22.6 percent, skin oedema or rash 22.7 percent, inguinal node tenderness 13.9 percent, inguinal enlargement 12.6 percent, axillary enlargement 11.0 percent, arthralgia or synovitis 9.3 percent. Facial oedema 1.2 percent, peripheral oedema 3.2 percent, orthostatic hypotension 1.1 percent, and tachycardia 3.5 percent were listed as drug-related at or above 1 percent. Headache and myalgia were common overall regardless of causality. Those percentages are a dying-microfilariae signal. They are not proof the tablet failed, and they are not a reason to invent a daily schedule.
The dangerous rare flag is different. People with onchocerciasis who also carry a heavy Loa loa load can develop encephalopathy - pain, red eye, conjunctival haemorrhage, incontinence, inability to stand, confusion, seizures, coma - after an effective microfilaricide. The label says pretreatment assessment for loiasis and careful follow-up when there has been significant exposure to West or Central African Loa-endemic areas. Sowda, the hyperreactive onchodermatitis phenotype, may react more severely, especially with oedema. Neurotoxicity has also been reported without Loa loa, generally resolving with support and stopping the drug. Trial-safety flags belong in the carton. They do not belong in a viral anecdote about a horse paste.
A year-long count is the post, not a cure
Post the onchocerciasis file as a count that lasts. Day 3 crash, month 3 near-wipe of skin microfilariae, month 12 still mostly down, adults still alive, MDA usually yearly, clinic retreatment as short as three months. That is a coherent trial signal. It matches the CDC onchocerciasis care note: one dose drops the load for a year or more; prolonged daily dosing has no evidence of extra benefit over the annual pass. Semiannual MDA can suppress skin microfilariae better than annual in some Ghanaian trial communities; albendazole added to ivermectin did not improve Onchocerca clearance in that design. Frequency is a programme choice. It is not a new molecule.
Do not post a cure. Do not post a viral win. Do not post a stool-cure percentage as if it were a skin-snip. The soil history explains why the carton exists. The working card turns 150 mcg/kg into a 3 mg stack. This trial file only ranks signals. If a reader brings a travel history from the African belt or a lab report with Onchocerca, the next conversation is with their own clinician, not with a comment thread. Edinburgh signs the teaching line. It does not sign a personal regimen.