Monday, September 3, 2018

Case of the Week 509

This week features our monthly case from Idzi Potters and the Institute of Tropical Medicine, Antwerp. The patient is a European male with recent travel to Senegal who presented with right conjunctivitis. On ocular examination, a 10-cm long worm was identified and removed from the right conjunctiva. It measured 470 micrometers in diameter.

A Knott's concentration was also performed on the patient's blood, revealing 6 larvae per milliliter. Each larva measured approximately 375 micrometers long by 10 micrometers wide.



Identification?

25 comments:

Sam said...

Loa loa

Unknown said...

Loa loa

Lyne C├ędilotte said...

Loa loa ( filaria)

Anonymous said...

The geography and eye infection point the diagnosis to Loa loa. Wish the shadow of the sheath could better captured in the pictures.
Florida Fan

Anonymous said...

Loa loa.
6 larvae per ml in the blood sounds like a terribly high parasite load. No other signs/symptoms than the conjunctivitis?
Bw in Vt

Curious Vet Parasitologist said...

Could it be Onchocerca volvulus? The mf seem unsheathed to me

Old One said...

A filared, but what species? I think further tests are required. There is one species that share many of the characteristics described in this case.

The adult worm appears to have longitudinal ridges. The microfilaria appear to be unsheathed and their size in Knott's preparation are consistent with Dirofilaria repens. However the tail of the microfilaria lacks the "button hook" characteristic of D. repens.

D. repens is a up and coming zoonotic in Europe. Most common in Italy but is spreading to other counties. Infections have occurred in human conjunctiva.

nema said...

Classic passage under the conjunctiva of an adult female with setting in the blood of microfilaria are in favor of filariasis in Loa Loa. This being in view of the maturation period of this wired (a few months) and the fact that the usual geographical area is Central Africa and not West Africa I think that it is necessary to look at this traveler the notion of previous trips. A Mondjo

Agnes Kurniawan said...

It is Loaloa adult worm in conjungtiva and confirmed by the microfilariae morphology

Blaine A. Mathison said...

I am going to have to side with the Old One on this case, I think this is Dirofilaria, and being from Europe, I would say D. repens.

I also see longitudinal cuticular ridges on the outside of the body of the worm. The microfilariae are about 100 micrometers too long and the adult about 30 cm too short to be Loa loa, and the nuclear arrangement is not right in the microfilaria.

Microfilaremia is rare in cases of human dirfilariasis, but not impossible!

Ayisi Frank said...

My first thought went to Loa loa but I'm beginning to reconsider that after reading the comments

Ayisi Frank said...

My first thought went to Loa loa but I'm beginning to reconsider that after reading the comments

Anonymous said...

Everything considered, Old One's and Blaine's comments seem to conclude the discrepancies such as the size of the adult and the lack of a clear sheath very well. Thank you very much for the comments.
Florida Fan

Anonymous said...

It's Loa loa!

Idzi P. said...

Hi everybody!
There is a nice discussion going on!
Prevalence of Loa loa in Senegal is worth checking.
Hi Blaine! Maybe also check size of adult Loa loa?
Cheerio to all of you!

Blaine Adam Mathison said...

DPDx has adult female Loa loa as being 40-70 cm long; males less than 3.5 cm (although I am sure there is wiggle room in size). But regardless of size the longitudinal ridges support Dirofilaria and rule-out Loa, which should have random pimple-like bosses. Also, at 375 um, the microfilaria is too long for L. loa (average length 230-350 um).

Idzi P. said...

Hi Blaine! DPDx seems to tell me that “The female worms measure 40 to 70 mm in length” (https://www.cdc.gov/dpdx/loiasis/index.html) ... I guess that either there’s a typo somewhere or ...

Blaine A. Mathison said...

Yes, that's a typo (I alerted them to it). Honestly, I am probably the one responsible for the typo since I wrote that text when I worked for DPDx LOL

Blaine A. Mathison said...

Wait, my mistake. That is correct. Sorry I was confusing it with Onchocerca. Uggh. I hate math LOL. I can never remember numbers. 22 years of parasitology and I still have to look up sizes LOL.

Females of L. loa are 4-7 cm. So the adult worm in the case is between the published sizes of Loa and Dirofilaria. But the cuticular morphology and microfilarial morphology still support Dirofilaria to me.

Old One said...

A wonderful, challenging case. Thanks Idzi P.

Senegal appears to be out of the distribution of Loa loa and is a stretch for Dirofilaria repens.

I must say that the appearance of the adult female reminded me so much of D. immitis.

Blaine A. Mathison said...

It can't be D. immitis. Dirofilaria immitis lacks the longitudinal cuticular ridges (it defines Dirofilaria at the subgenus level).

The average length for a mf of D. repens in 369 micrometers.

D. repens is endemic to Europe too.

Given the epi, morphology, and measurements I am standing firmly behind a diagnosis of Dirofilaria repens (genus is sound).

Old One said...

I'm still leaning toward D. repens.

Old One said...

I'm in complete agreement with Blaine

Blaine A. Mathison said...

Something all of our ‘pupils’ should know, to keep an ‘eye’ out for important differentials...yes, I know...my jokes are ‘cornea’!

Idzi P. said...

Hahaaa!
Blaine’s humor never lets us down!
Any additional questions one could ask to our patient?