A 20-Year Longitudinal Study of Plasmodium ovale and Plasmodium malariae Prevalence and Morbidity in a West African Population

Abstract

Background Plasmodium ovale and Plasmodium malariae have long been reported to be widely distributed in tropical Africa and in other major malaria-endemic areas of the world. However, little is known about the burden caused by these two malaria species.Methods and FindingsWe did a longitudinal study of the inhabitants of Dielmo village, Senegal, between June, 1990, and December, 2010. We monitored the inhabitants for fever during this period and performed quarterly measurements of parasitemia. We analyzed parasitological and clinical data in a random-effect logistic regression model to investigate the relationship between the level of parasitemia and the risk of fever and to establish diagnostic criteria for P. ovale and P. malariae clinical attacks. The prevalence of P. ovale and P. malariae infections in asymptomatic individuals were high during the first years of the project but decreased after 2004 and almost disappeared in 2010 in relation to changes in malaria control policies. The average incidence densities of P. ovale and P. malariae clinical attacks were 0.053 and 0.093 attacks per person per year in children <15 years and 0.024 and 0.009 attacks per person per year in adults ≥15 years, respectively. These two malaria species represented together 5.9% of the malaria burden.Conclusions P. ovale and P. malariae were a common cause of morbidity in Dielmo villagers until the recent dramatic decrease of malaria that followed the introduction of new malaria control policies. P. ovale and P. malariae may constitute an important cause of morbidity in many areas of tropical Africa.

High Prevalence of Mansonella perstans Filariasis in Rural Senegal

“…5,24 On each slide, 200 oil-immersion fields (∼0.5 μL blood) were examined, and the filarial:leukocyte ratio was measured. 25,26 Arthropod collection. Insects were collected using a modified CDC light trap (BioQuip Products, Compton, CA), as previously reported.…”

Parasitological correlates of Plasmodium ovale curtisi and Plasmodium ovale wallikeri infection

“…Plasmodium ovale is one species of malaria parasites that is pathogenic to humans [1]. Prevalent in West and East Africa and the Asia–Pacific [1], P. ovale infections can be challenging to diagnose in part due to the typical presentation of clinically mild disease and low parasite burden [2].…”

“…Prevalent in West and East Africa and the Asia–Pacific [1], P. ovale infections can be challenging to diagnose in part due to the typical presentation of clinically mild disease and low parasite burden [2]. Consequently, conventional diagnostic tools, such as microscopy of blood films and rapid diagnostic tests (RDT), have limited performance in detecting P. ovale infection [3–5], often resulting in the use of molecular techniques to confirm the diagnosis [5].…”

Plasmodium infections and fluctuating asymmetry among children and teenagers from Senegal

“…Maximum threshold values in young children for P. ovale and malariae clinical attacks ranged from 3800/ll to 2000/ll according to study periods and decreased to 350-300/ll in older adults (Roucher et al, 2014). For Plasmodium falciparum, maximum threshold values in young children ranged from 21,500/ll to 10,000/ll and minimum values in older adults from 2000/ll to 500/ll (Roucher et al, 2012(Roucher et al, , 2014. For infants, thick blood films were taken twice a month up to six months and we attributed fever episodes to malaria when the onset of fever corresponded either to the onset of patent parasitaemia and/or to peaks of high parasitaemia.…”

“…We attributed fever to malaria when parasite density was higher than an age-dependent threshold calculated for each Plasmodium species during the corresponding period according to methods described in Roucher et al (2012). Maximum threshold values in young children for P. ovale and malariae clinical attacks ranged from 3800/ll to 2000/ll according to study periods and decreased to 350-300/ll in older adults (Roucher et al, 2014). For Plasmodium falciparum, maximum threshold values in young children ranged from 21,500/ll to 10,000/ll and minimum values in older adults from 2000/ll to 500/ll (Roucher et al, 2012(Roucher et al, , 2014.…”