High asymptomatic malaria among seasonal migrant workers departing to home from malaria endemic areas in northwest Ethiopia

Tilaye, Tesfaye; Tessema, Belay; Alemu, Kassahun

doi:10.1186/s12936-022-04211-9

Cited by 12 publications

(13 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To this end, we recruited 511 FC and 175 RC. The majority of FC and RC were aged 18-29 years and most were male as observed in other studies performed in Northwest Ethiopia(12, 52-55)…”

Section: Discussionsupporting

confidence: 69%

Demographic characteristics and prevalence of asymptomaticLeishmania donovaniinfection in migrant workers working in an endemic area in Northwest Ethiopia

Yimer,

Takele,

Yizengaw

et al. 2024

Preprint

View full text Add to dashboard Cite

Visceral leishmaniasis (VL), a neglected tropical disease that causes substantial morbidity and mortality, is a serious health problem in Ethiopia. Infections are caused byLeishmania(L.)donovaniparasites. Most individuals remain asymptomatic, but some develop VL, which is fatal if not treated.We identified the area of Metema-Humera in Northwest Ethiopia as a setting in which we could follow migrant workers when they arrived in an endemic area. The demographic characteristics of this population and factors associated with their risk of asymptomatic infection are poorly characterised. We divided our cohort into individuals who visited this area for the first time (first comers, FC) and those who had already been in this area (repeat comers, RC). We followed them from the beginning (Time 1, T1) to the end of the agricultural season (Time 2, T2), performing tests for sand fly bite exposure (anti-sand fly saliva antibody ELISA) and serology forLeishmaniainfection (rK39 rapid diagnostic test and the direct agglutination test) at each time point and collecting information on risk factors for infection.Our results show that most migrant workers come from non-endemic areas, are male, young (median age of 20 years) and are farmers or students.At T1, >80% of them had been already exposed to sand fly bites, as shown by the presence of anti-saliva antibodies. However, due to seasonality of sand flies there was no difference in exposure between FC and RC, or between T1 and T2. The serology data showed that at T1, but not at T2, a significantly higher proportion of RC were asymptomatic. Furthermore, 28.6% of FC became asymptomatic between T1 and T2. Over the duration of this study, one FC and one RC developed VL.In multivariable logistic regression of asymptomatic infection at T1, only age and the number of visits to Metema/Humera were significantly associated with asymptomatic infection.A better understanding of the dynamics of parasite transmission and the risk factors associated with the development of asymptomatic infections and potentially VL will be essential for the development of new strategies to prevent leishmaniasis.

show abstract

“…To this end, we recruited 511 FC and 175 RC. The majority of FC and RC were aged 18-29 years and most were male as observed in other studies performed in Northwest Ethiopia(12, 52-55)…”

Section: Discussionsupporting

confidence: 69%

Demographic characteristics and prevalence of asymptomaticLeishmania donovaniinfection in migrant workers working in an endemic area in Northwest Ethiopia

Yimer,

Takele,

Yizengaw

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…Migration from the highlands to the lowlands is common, either for short-term visits or to work on large farms (8)(9)(10). Highly malaria-endemic lowland areas may serve as a source of malaria transmission to low malaria-endemic highland areas.…”

Section: Introductionmentioning

confidence: 99%

“…Highly malaria-endemic lowland areas may serve as a source of malaria transmission to low malaria-endemic highland areas. Travel has been implicated as a major risk factor for P. falciparum infection in low-transmission areas in Ethiopia (5,11), and the return of travelers to the highlands has been associated with increased numbers of malaria infections (8)(9)(10). However, the potential contribution of returnees to malaria transmission in the highlands is not clear.…”

Section: Introductionmentioning

confidence: 99%

Plasmodium falciparumtransmission in the highlands of Ethiopia is driven by closely related and clonal parasites

Holzschuh¹,

Ewnetu²,

Carlier³

et al. 2023

Preprint

View full text Add to dashboard Cite

Malaria cases are frequently recorded in the Ethiopian highlands even at altitudes above 2,000 m. The epidemiology of malaria in the Ethiopian highlands, and in particular the role of importation by human migration from the highly endemic lowlands is not well understood. We characterized the parasite population structure and genetic relatedness by sequencing 159 P. falciparum samples from Gondar and an additional 28 samples from Ziway using a highly multiplexed droplet digital PCR (ddPCR)-based amplicon deep sequencing method targeting 35 microhaplotypes and drug resistance loci. Diversity was moderate (mean HE: 0.54), and infection complexity was low (74.9% single clone infections). A significant percentage of infections shared genomic haplotypes, even across transmission seasons, indicating persistent local and focal transmission. Multiple clusters of clonal or near-clonal infections were identified, highlighting the overall high genetic relatedness. Frequently, infections from travelers were the earliest observed cases, suggesting that parasites may have been imported and then transmitted locally. We observed population structure between Gondar and Ziway, although some haplotypes were shared between sites. 31.1% of infections carried pfhrp2 deletions and 84.4% pfhrp3 deletions, and 28.7% pfhrp2/pfhrp3 double deletions. Parasites with pfhrp2/3 deletions and wild-type parasites were genetically distinct. Mutations associated with resistance to sulfadoxine-pyrimethamine and lumefantrine were observed at near-fixation, but no mutations in pfk13 were found. In conclusion, genomic data corroborates local transmission and the importance of intensified control in the Ethiopian highlands.

show abstract

“…Historically, areas above 2000 m were considered malaria‐free in Ethiopia (FMoH, 2020), but in the Gondar region, a high number of cases were observed during the wet season (Ewnetu, et al., unpublished data). Seasonal migration from highly endemic lowland areas may contribute significantly to highland malaria transmission (Lemma, 2020; Malede et al., 2018; Tilaye et al., 2022), but the dynamics of highland transmission remain elusive.…”

Section: Discussionmentioning

confidence: 99%

“…The highlands are considered regions of ‘unstable’ malaria transmission (Rodó et al., 2021; Siraj et al., 2014). Migration from the highlands to the lowlands is common, either for short‐term visits or to work on large farms (Lemma, 2020; Malede et al., 2018; Tilaye et al., 2022). Highly malaria‐endemic lowland areas may serve as a source of malaria transmission to low malaria‐endemic highland areas.…”

Section: Introductionmentioning

confidence: 99%

Plasmodium falciparum transmission in the highlands of Ethiopia is driven by closely related and clonal parasites

Holzschuh,

Ewnetu,

Carlier

et al. 2024

Molecular Ecology

View full text Add to dashboard Cite

Malaria cases are frequently recorded in the Ethiopian highlands even at altitudes above 2000 m. The epidemiology of malaria in the Ethiopian highlands, and, in particular, the role of importation by human migration from the highly endemic lowlands is not well understood. We sequenced 187 Plasmodium falciparum samples from two sites in the Ethiopian highlands, Gondar (n = 159) and Ziway (n = 28), using a multiplexed droplet digital PCR (ddPCR)‐based amplicon sequencing method targeting 35 microhaplotypes and drug resistance loci. Here, we characterize the parasite population structure and genetic relatedness. We identify moderate parasite diversity (mean HE: 0.54) and low infection complexity (74.9% monoclonal). A significant percentage of infections share microhaplotypes, even across transmission seasons and sites, indicating persistent local transmission. We identify multiple clusters of clonal or near‐clonal infections, highlighting high genetic relatedness. Only 6.3% of individuals diagnosed with P. falciparum reported recent travel. Yet, in clonal or near‐clonal clusters, infections of travellers were frequently observed first in time, suggesting that parasites may have been imported and then transmitted locally. 31.1% of infections are pfhrp2‐deleted and 84.4% pfhrp3‐deleted, and 28.7% have pfhrp2/3 double deletions. Parasites with pfhrp2/3 deletions and wild‐type parasites are genetically distinct. Mutations associated with resistance to sulphadoxine–pyrimethamine or suggested to reduce sensitivity to lumefantrine are observed at near‐fixation. In conclusion, genomic data corroborate local transmission and the importance of intensified control in the Ethiopian highlands.

show abstract

High asymptomatic malaria among seasonal migrant workers departing to home from malaria endemic areas in northwest Ethiopia

Cited by 12 publications

References 49 publications

Demographic characteristics and prevalence of asymptomaticLeishmania donovaniinfection in migrant workers working in an endemic area in Northwest Ethiopia

Demographic characteristics and prevalence of asymptomaticLeishmania donovaniinfection in migrant workers working in an endemic area in Northwest Ethiopia

Plasmodium falciparumtransmission in the highlands of Ethiopia is driven by closely related and clonal parasites

Plasmodium falciparum transmission in the highlands of Ethiopia is driven by closely related and clonal parasites

Contact Info

Product

Resources

About