Characterising co-infections with Plasmodium spp., Mansonella perstans or Loa loa in asymptomatic children, adults and elderly people living on Bioko Island using nucleic acids extracted from malaria rapid diagnostic tests

Abstract

Background Regular and comprehensive epidemiological surveys of the filarial nematodes Mansonella perstans and Loa loa in children, adolescents and adults living across Bioko Island, Equatorial Guinea are lacking. We aimed to demonstrate that blood retained on malaria rapid diagnostic tests, commonly deployed for malaria surveys, could be used as a source of nucleic acids for molecular based detection of M. perstans and L. loa. We wanted to determine the positivity rate and distribution of filarial nematodes across different age groups and geographical areas as well as to understand level of co-infections with malaria in an asymptomatic population. Methodology M. perstans, L. loa and Plasmodium spp. parasites were monitored by qPCR in a cross-sectional study using DNA extracted from a subset malaria rapid diagnostic tests (mRDTs) collected during the annual malaria indicator survey conducted on Bioko Island in 2018. Principal findings We identified DNA specific for the two filarial nematodes investigated among 8.2% (263) of the 3214 RDTs screened. Positivity rates of M. perstans and L. loa were 6.6% and 1.5%, respectively. M. perstans infection were more prominent in male (10.5%) compared to female (3.9%) survey participants. M. perstans parasite density and positivity rate was higher among older people and the population living in rural areas. The socio-economic status of participants strongly influenced the infection rate with people belonging to the lowest socio-economic quintile more than 3 and 5 times more likely to be L. loa and M. perstans infected, respectively. No increased risk of being co-infected with Plasmodium spp. parasites was observed among the different age groups. Conclusions/Significance We found otherwise asymptomatic individuals were infected with M. perstans and L. loa. Our study demonstrates that employing mRDTs probed with blood for malaria testing represents a promising, future tool to preserve and ship NAs at room temperature to laboratories for molecular, high-throughput diagnosis and genotyping of blood-dwelling nematode filarial infections. Using this approach, asymptomatic populations can be reached and surveyed for infectious diseases beyond malaria.

Development and evaluation of PlasmoPod: A cartridge-based nucleic acid amplification test for rapid malaria diagnosis and surveillance

“…The used RDTs were stored at room temperature in plastic bags with desiccants and subsequently transported to the Swiss Tropical and Public Health Institute for additional molecular analysis. Total nucleic acids were extracted by the “Extraction of Nucleic Acids from RDTs” (ENAR) protocol and [ 19 , 20 ] and the pan- Plasmodium spp. 18S ribosomal DNA and RNA molecules were targeted [ 18 , 21 ] and detected by a highly-sensitive RT-qPCR (herein referred to Pspp18S RT-qPCR assay) [ 19 ].…”

Nodding Syndrome, a Case-control Study in Mahenge, Tanzania: <em>Onchocerca volvulus </em>and not <em>Mansonella </em><em>perstans</em> as Risk Factor

“…Factors associated with poverty also have the potential to explain an association between M. perstans infection and NS. Indeed, a study on Bioko Island, Equatorial Guinea, showed that people belonging to the lowest socioeconomic quintile were five times more likely to be M. perstans infected [42]. Children with NS and their families also belong to the poorest and most vulnerable groups in their communities [43].…”

Prevalence, probability, and characteristics of malaria and filariasis co-infections: A systematic review and meta-analysis

“…We estimated the pooled prevalence of malaria and filariasis co-infections among participants using the data available from 17 studies [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Results of the meta-analysis showed that the pooled prevalence of malaria and filariasis co-infections among participants was 11% (95% confidence interval (CI): 8%-13%, I 2 , 96.7%, 17 studies; Fig 3).…”

“…The pooled prevalence of malaria and L. loa co-infections among participants was estimated using the data available from five studies [24,26,28,32,38]. The results of the meta-analysis showed that participants' pooled prevalence of malaria and L. loa co-infections was 1.2% (95% CI: 0.5%-1.9%, I 2 , 84%, 5 studies; Fig 5).…”

“…The probability of malaria and filariasis co-infections was estimated using the data available from 16 studies [22][23][24][25][27][28][29][30][31][32][33][34][35][36][37][38]. The results of the meta-analysis showed that the co-infections between the two parasites occurred by probability (P = 0.001, OR: 0.34, 95% CI: 0.19-0.62, I 2 : 95.7%, 16 studies; Fig 7).…”