Removal of adult subconjunctival Loa loa amongst urban dwellers in Nigeria

Clinical and epidemiological features of imported loiasis in Beijing: a report from patients returned from Africa

BACKGROUND

Loiasis is one of the significant filarial diseases for people living in West and Central Africa with wide endemic area but is not seen in China. As economy booms and international traveling increase, China faces more and more imported parasitic diseases that are not endemic locally. Loiasis is one of the parasitic diseases that enter China by travelers infected in Africa. The better understanding of the clinical and laboratory features of loa loa infection will facilitate the diagnosis and treatment of loiasis in China.

METHODS

The study targeted travelers who were infected with L. loa in endemic Africa regions and returned to Beijing between 2014 and 2023. Epidemiological, clinical, and biological data as well as treatment of these patients were collected.

RESULTS

Total 21 cases were identified as L. loa infection based on their typical clinical manifestations and parasite finding. All cases had a history of travel to Africa for more than 6 months, most of them are the construction workers dispatched to West Africa with outdoor activities. Calabar swelling (n = 19; 90.5%) and pruritus (n = 11; 52.4%) were among the most common clinical symptoms followed by muscle pain (n = 7; 33.3%) and skin rash (n = 2; 9.5%). The adult worms were observed in the eyelid or subconjunctiva (n = 2; 9.5%) and subcutaneous tissues (n = 2; 9.5%). Although all patients presented with a high eosinophil count (> 0.52 × 109/L), only two cases displayed microfilariae in fresh venous blood and positive for filarial antigen. A cut section of adult worm was observed through biopsy on a skin nodule surrounded by lymphocytes, plasma cells and eosinophils. All subjects were positive in PCR targeting L. loa ITS-1. The constructed phylogenetic tree based on the amplified ITS-1 sequences identified their genetical relation to the L. Loa from Africa. All patients treated with albendazole and diethylcarbamazine were recovered without relapse.

CONCLUSION

This study provides useful information and guideline for physicians and researchers in non-endemic countries to diagnose and treat loiasis and L. loa infections acquired from endemic regions.

Loa loa in the Vitreous Cavity of the Eye: A Case Report and State of Art

Loa loa is a filarial nematode responsible for loiasis, endemic to West-Central Africa south of the Sahara and transmitted by flies. This study reports a case of L. loa in the vitreous cavity of the eye of a young patient, along with an in-depth literature review. A 22-year-old woman from Cameroon who migrated from Cameroon to Italy was referred to the Emergency Ophthalmology Department at Policlinico di Bari in July 2021 with the presence of a moving parasite in the subconjunctiva of the left eye. A recent onset of a papular lesion on the dorsal surface of the right wrist and a nodular lesion in the scapular region were detected. L. loa filariasis was diagnosed based on anamnestic data, clinical and paraclinical signs, and a parasitological test confirming the presence of microfilariae in two blood samples collected in the morning of two different days. Because of the unavailability of diethylcarbamazine (DEC), albendazole (ALB) 200 mg twice daily was administered for 21 days. A mild exacerbation of pruritus occurred during treatment, but resolved with the use of an antihistamine. A single dose of 12 mg ivermectin was prescribed at the end of the treatment with albendazole. Unlike other endemic parasite infections, L. loa is not included in the Global Program to Eliminate Lymphatic Filariasis, because it is not mentioned in the WHO and CDC list of neglected tropical diseases. This can result in an overall risk of lack of attention and studies on loiasis, with lack of data on global burden of the disease.

A case of Subconjunctival Filariasis in Abuja,Nigeria

The report presents a case of subconjunctival filariasis in a 20-year-old female student who schools in Oye-Ekiti, Ekiti State, a known loa loa endemic region in Nigeria, and resident in Abuja. The patient presented on the 20th of February 2020, with a history of foreign body sensation and itching on two occasions within a 6-month period and had video evidence of a worm in her left eye. The worm was however not visualized in the clinic. She was placed on tabs Albendazole 20mg twice daily for 21 days and has not felt or seen the worm since she completed the medications. Subconjunctival filariasis is still an issue of concern in the rainforest region of Nigeria.

OUP accepted manuscript

Loa loa microfilariae were found on thick blood smears (TBSs) from 8 of 300 (2.7%) residents of Bioko Island, Equatorial Guinea, during a Plasmodium falciparum sporozoite malaria vaccine clinical trial. Only one subject was found to have microfilaraemia on his first exam; parasites were not discovered in the other seven until subsequent TBSs were performed, at times many weeks into the study. All infected individuals were asymptomatic, and were offered treatment with diethylcarbamazine, per national guidelines. L. loa microfilaraemia complicated the enrolment or continued participation of these eight trial subjects, and only one was able to complete all study procedures. If ruling out loiasis is deemed to be important during clinical trials, tests that are more sensitive than TBSs should be performed.