Prevalence Of Asymptomatic Parasitaemia Research Articles

Prevalence of asymptomatic malaria parasitaemia following mass testing and treatment in Pakro sub-district of Ghana

BackgroundGlobal efforts to scale-up malaria control interventions are gaining steam. These include the use of Long-Lasting Insecticide Nets, Indoor Residual Spraying, Intermittent Preventive Treatment and Test, Treat and Track. Despite these, the drive for malaria elimination is far from being realistic in endemic communities in Africa. This is partly due to the fact that asymptomatic parasite carriage, not specifically targeted by most interventions, remains the bedrock that fuels transmission. This has led to mass testing, treatment and tracking (MTTT) as an alternative strategy to target asymptomatic individuals. We report the impact of MTTT on the prevalence of asymptomatic malaria parasitaemia over a one-year period in Ghana, hypothesizing that implementing MTTT could reduce the rate of asymptomatic parasitaemia.MethodsA population of about 5000 individuals in seven communities in the Pakro sub-district of Ghana participated in this study. A register was developed for each community following a census. MTTT engaged trained community-based health volunteers who conducted house-to-house testing using RDTs every 4 months and treated positive cases with Artemisinin–based Combination Therapy. Between interventions, community-based management of malaria was implemented for symptomatic cases.ResultsMTTT Coverage was 98.8% in July 2017 and 79.3% in July 2018. Of those tested, asymptomatic infection with malaria parasites reduced from 36.3% (1795/4941) in July 2017 to 32.9% (1303/3966) in July 2018 (p = 0.001). Prevalence of asymptomatic parasitaemia among children under 15 years declined from 52.6% (1043/1984) in July 2017 to 47.5% (820/1728) in July 2018 (p = 0.002). Implementing MTTT significantly reduced asymptomatic parasitaemia by 24% from July 2017 to July 2018 after adjusting for age, ITN use and axillary temperature (OR = 0.76, CI = 0.67, 0.85 p ≤ 0.001).ConclusionThis study has demonstrated that implementing MTTT is feasible and could reduce the prevalence of asymptomatic malaria parasitaemia in children under 15 years of age. Furthermore, the use of community-based health volunteers could ensure high coverage at lower cost of implementation.Trial registrationNCT04167566, Date 14/11/2019. Retrospective registration.

Malaria burden in a birth cohort of HIV-exposed uninfected Ugandan infants living in a high malaria transmission setting.

BackgroundHIV-exposed, uninfected (HEU) infants suffer high morbidity and mortality in the first year of life compared to HIV-unexposed, uninfected (HUU) infants, but accurate data on the contribution of malaria are limited.MethodsThe incidence of febrile illnesses and malaria were evaluated in a birth cohort of HEU infants. Infants were prescribed daily trimethoprim–sulfamethoxazole (TS) prophylaxis from 6 weeks of age until exclusion of HIV-infection after cessation of breastfeeding. Infants were followed for all illnesses using passive surveillance and routine blood smears were done monthly. Malaria was diagnosed as a positive blood smear plus fever. Placental malaria was determined by histopathology, placental blood smear and PCR. Risk factors for time to first episode of malaria were assessed using a Cox proportional hazards model. Malaria incidence among HEU infants aged 6–12 months was compared to that in other cohorts of HEU and HUU infants from the same region.ResultsAmong 361 HEU infants enrolled, 248 completed 12 months of follow-up resulting in 1562 episodes of febrile illness and 253 episodes of malaria after 305 person-years of follow-up. The incidence of febrile illness was 5.12 episodes per person-year (PPY), ranging from 4.13 episodes PPY in the first 4 months of life to 5.71 episodes PPY between 5 and 12 months of age. The overall malaria incidence was 0.83 episodes per person-year (PPY), increasing from 0.03 episodes PPY in the first 2 months of life to 2.00 episodes PPY between 11 and 12 months of age. There were no episodes of complicated malaria. The prevalence of asymptomatic parasitaemia was 1.2 % (19 of 1568 routine smears positive). Infants born to mothers with parasites detected from placental blood smears were at higher risk of malaria (hazard ratio = 4.51, P < 0.001). HEU infants in this study had a 2.4- to 3.5-fold lower incidence of malaria compared to HUU infants in other cohort studies from the same area.ConclusionThe burden of malaria in this birth cohort of HEU infants living in a high-transmission setting and taking daily TS prophylaxis was relatively low. Alternative etiologies of fever should be considered in HEU-infants taking daily TS prophylaxis who present with fever. Trial Registration NCT00993031, registered 8 October, 2009

Microscopic and molecular evidence of the presence of asymptomatic Plasmodium falciparum and Plasmodium vivax infections in an area with low, seasonal and unstable malaria transmission in Ethiopia.

BackgroundThe presence of asymptomatic infections has serious implications for malaria elimination campaigns. Since asymptomatic carriers do not seek treatment for their infection and may become gametocyte carriers, they undoubtedly contribute to the persistence of malaria transmission in a population. The presence of asymptomatic parasitemias was noted in areas with seasonal malaria transmission. In Ethiopia there is a paucity of data regarding the prevalence of asymptomatic malaria carriage. This study was undertaken to assess the presence and prevalence of asymptomatic Plasmodium falciparum and Plasmodium vivax infections in south-central Oromia, Ethiopia.MethodsA total of 1094 apparently healthy individuals ≥ 2 years of age in south-central Oromia, Ethiopia, an area with seasonal and unstable malaria transmission, were screened for the presence of asymptomatic plasmodial infections. Finger-prick blood samples were taken from each participant for blood film preparation for microscopy and the rapid diagnostic test (RDT). Blood samples were also spotted on Whatman 3MM filter paper for parasite DNA extraction.ResultsThe prevalence of asymptomatic Plasmodium carriage (P. falciparum, P. vivax and mixed species) was 5.0 % (55/1,094) as determined by microscopy, while the prevalence as determined using RDT was 8.2 % (90/1,094). PCR was done on 47 of 55 microscopy-confirmed and on 79 of 90 RDT-confirmed samples. PCR detected parasite DNA in 89.4 % (42/47) of the microscopy-positive samples and in 77.2 % (61/79) of the RDT-positive samples. No significant difference was observed in the prevalence of asymptomatic P. falciparum or P. vivax infections in the study area (P > 0.1). However, the prevalence of asymptomatic parasitaemia was significantly associated with gender (OR = 0.47, P = 0.015; being higher in males than females) and age (X2 = 25, P < 0.001; being higher in younger than in older individuals). Age and parasite densities had an inverse relationship.ConclusionsThis study confirms the presence of asymptomatic P. falciparum and P. vivax infections in south-central Oromia, an area with low, seasonal and unstable malaria transmission in Ethiopia. Of 55 microscopically confirmed asymptomatic infections, P. falciparum monoinfection accounted for 45.5 % and of 90 RDT positive asymptomatic infections, 66.7 % were P. falciparum. Although not statistically significant, P. falciparum accounted for a relatively large number of the asymptomatic infections as determined by both tests. The prevalence of asymptomatic parasitaemia was highest in the younger age group. HRP-2-based RDTs specific for P. falciparum showed high false positivity rate compared to Plasmodium lactate dehydrogenase (pLDH) specific to P. vivax. Although microscopy and RDT detected substantial numbers of asymptomatic infections in apparently healthy inhabitants, the use of a highly sensitive molecular diagnostics offers a more accurate assessment of the magnitude of asymptomatic infections.

The clinical impact of combining intermittent preventive treatment with home management of malaria in children aged below 5 years: cluster randomised trial

To investigate the impact of seasonal intermittent preventive treatment (IPTc) on malaria-related morbidity in children <5 years of age who already had access to home-based management of malaria (HMM) for presumptive treatment of fevers. Thirty community-based drug distributors (CDDs) from all 13 communities of a rural subdistrict in Ghana were trained to provide prompt treatment for presumptive malaria using artesunate-amodiaquine (AS+AQ) to all children under 5 years of age. Six communities were randomised to also receive bimonthly courses of seasonal IPTc with AS+AQ in May, July and September of 2007. The primary outcome was the incidence rate of febrile episodes diagnosed presumptively as malaria by the CDDs in the communities in each intervention group. Cross-sectional surveys were conducted to determine the prevalence of parasitaemia and anaemia among the study children. During the 6 months in which IPTc was delivered, incidence of fevers in communities given HMM+IPTc was lower than in communities given HMM alone, but this difference was not statistically significant (protective efficacy: 37.0%(95% CI: -9.7 to 63.8; P = 0.14). However, incidence of presumptive malaria was significantly lower in IPTc communities when only children who received all three courses of IPTc were included in the analysis: protective efficacy 61.5% (95% CI:31.2-78.5; P = 0.018). Protection with IPTc was not followed by rebound morbidity in the following year. At the end of the intervention period, prevalence of asymptomatic parasitaemia was lower in communities that had received IPTc, but there were no differences in anaemia or haemoglobin concentration. In this study area, incidence of fevers was lower in communities given three courses of IPTc during the time of peak transmission than in communities that received only HMM. However, high levels of coverage for IPTc will be necessary for maximum impact.

Malaria preventive measures, health care seeking behaviour and malaria burden in different epidemiological settings in Sudan

To provide information about preventive measures and treatment seeking behaviour as well as an estimate of the malaria burden in different epidemiological settings for effective monitoring and evaluation of the ongoing efforts. Cross-sectional survey carried out in four areas representing different levels of transmission to explore the use of preventive measures, care-seeking behaviour and accessibility in addition to point prevalence was followed by a follow-up phase in which the health workers registered and reported all fever cases including malaria. The relation between the reported malaria incidence, the product of symptomatic/asymptomatic ratio and the prevalence of confirmed malaria cases was used to develop the equation that could predict the true malaria incidence. Thousand households and 3628 individuals were surveyed. The presence of any net varied between 6.6% and 40%; the percentage of people who reportedly slept under mosquito nets in the previous night varied between 35 and 80. Prompt use of medications ranged between 14 and 48% with a delay of more than 24 h noticed in different areas. The mean number of individuals per household who reported use of anti-malarial drugs in the last 2 weeks ranged between 0.6 (SD = 0.92) and 1.2 (SD = 1.1), with variable cost per treatment and affordability. The prevalence of asymptomatic parasitaemia, fever and confirmed malaria at time of the survey differed by area. The incidence of malaria during the follow-up period was estimated to be 8.5, 178.6, 23.7 and 10.3 episodes per 1000 population in Malakal, Elrank, Elhosh and El Matama, respectively. Based on this, a prediction equation was developed. We found suboptimal health care seeking behaviour, coverage and use of preventive measures with a high malaria burden. We developed a model for future estimation of malaria episodes.

Asymptomatic parasitaemia as a risk factor for symptomatic malaria in a cohort of Ugandan children.

To assess the prevalence of asymptomatic parasitaemia, determine its association with symptomatic malaria, and identify independent predictors of asymptomatic parasitaemia in a cohort of children from Kampala, Uganda. A total of 316 children aged 6 months to 5 years were recruited from the community. The prevalence of asymptomatic parasitaemia was assessed at enrollment and approximately every 30 days during follow-up. Participants received all of their health care in our clinic, including a standardized approach to the diagnosis and treatment of symptomatic malaria. A total of 283 (90%) subjects completed the full 1-year follow-up and were included in this study, yielding 2557 routine smears. The prevalence of asymptomatic parasitaemia was 17% at enrollment, but 5-8% for the remainder of the study. The risk of developing symptomatic malaria within 30 days was significantly higher in those with a positive routine than in those with a negative one (50%vs. 9%, P < 0.001). Higher parasite densities were associated with increased odds of developing symptomatic malaria within 30 days (P = 0.003). Only 11% of episodes of asymptomatic parasitaemia, involving 6% of subjects, arose and cleared without therapy. In multivariate analysis the only significant risk factor for asymptomatic parasitaemia was whether a child had any episode of symptomatic malaria during the course of the study (OR = 3.0, P = 0.02). In our cohort of children from an urban meso-endemic environment, asymptomatic parasitaemia was uncommon and frequently followed by symptomatic malaria. This suggests that presumptive treatment of asymptomatic parasitaemia in such settings would be an efficient means of preventing symptomatic malaria.