The Population Biology and Transmission Dynamics of Loa loa

Abstract

African eye worm (caused by the filarial nematode Loa loa) -affects more than 10 million people. Despite causing ocular and systemic symptoms, it has typically been considered a benign condition, only of public health relevance because it impedes mass drug administration-based interventions against onchocerciasis and lymphatic filariasis in co-endemic areas. Recent research has challenged this conception, demonstrating excess mortality associated with high levels of infection, implying that loiasis warrants attention as an intrinsic public health problem. This review summarises available information on the key parasitological, entomological, and epidemiological characteristics of the infection and argues for the mobilisation of resources to control the disease, and the development of a mathematical transmission model to guide deployment of interventions.

Validation of Loop Mediated Isothermal Amplification for the detection of Loa loa infection in Chrysops spp in experimental and natural field conditions

“…In the western and central Africa, co-infection of loiasis with onchocerciasis are predominately prevalent [55] and thus entomological evaluation of L. loa in the vectors would therefore assist in the development of mathematical models of loiasis transmission and control. While this may not be a solution to reducing the risk of SAEs in the short-term, it would provide long-term bene ts as the construction of a mathematical model re ecting the epidemiological features of L. loa, both in the vector and human host would consequently enable assessing the indirect impact of interventions intended to control and eliminate onchocerciasis or LF and in evaluating the need for further interventions speci cally targeting loiasis [56]. Thus, surveying Chrysops infection rates in areas where Onchocerca volvulus and L. Loa are co-endemic is a rapid and an important indicator of transmission which has long depended on microscopic examination.…”

Impact of repeated annual community directed treatment with ivermectin on loiasis parasitological indicators in Cameroon: Implications for onchocerciasis and lymphatic filariasis elimination in areas co-endemic with Loa loa in Africa

“…Contrary to onchocerciasis, for which mathematical models exist that predict the impact of repeated annual ivermectin treatment on the parasitological and entomological indicators of transmission [ 33 , 34 ], no such models of prediction exist yet for L . loa [ 35 ]. We do not, therefore, have information on what the expected infection levels should be after a decade or more of ivermectin MDA with given levels of coverage and adherence.…”

“…With these double penalties L . loa is inflicting to the control of onchocerciasis and LF in the forest areas of the central African region, there is a pressing need of facing the control of this parasite [ 35 ]. One long-lasting solution to L .…”

Comparison of Three PCR-Based Methods to Detect Loa loa and Mansonella perstans in Long-Term Frozen Storage Dried Blood Spots

“…Among all human larial species, two of the most predominant species in Africa are L. loa and M. perstans [7,8], on which this study has focused Loa Loa, the parasite that causes loiasis (also known as African eye worm) [9], is endemic in eleven countries of Africa according to the Rapid Assessment Procedure for Loiasis (RAPLOA): Angola, Cameroon, Central African Republic, Chad, Congo, Democratic Republic of the Congo, Equatorial Guinea, Ethiopia, Gabon, Nigeria and Sudan [7,10,11]. Ten countries have areas where there are high rates of infection (more than 40% of the people who live in that area report that they have had eye worm in the past).…”

“…In several endemic areas, loiasis co-exists with onchocerciasis and lymphatic lariasis (LF), both classi ed as neglected tropical diseases (NTD) by the World Health Organization (WHO) [12]. The increasing importance of L. loa began when severe adverse events (SAE) presenting as encephalopathy following treatment with ivermectin occurred in areas where loiasis is co-endemic with onchocerciasis and/or LF, especially in very high micro larial loads ( 30000 micro lariae per millilitre (mf/mL) [9,10].…”