Transmission potential of Rickettsia felis infection by Anopheles gambiae mosquitoes

A growing number of recent reports have implicated Rickettsia felis as a human pathogen, paralleling the increasing detection of R. felis in arthropod hosts across the globe, primarily in fleas. Here Anopheles gambiae mosquitoes, the primary malarial vectors in sub-Saharan Africa, were fed with either blood meal infected with R. felis or infected cellular media administered in membrane feeding systems. In addition, a group of mosquitoes was fed on R. felis-infected BALB/c mice. The acquisition and persistence of R. felis in mosquitoes was demonstrated by quantitative PCR detection of the bacteria up to day 15 postinfection. R. felis was detected in mosquito feces up to day 14. Furthermore, R. felis was visualized by immunofluorescence in salivary glands, in and around the gut, and in the ovaries, although no vertical transmission was observed. R. felis was also found in the cotton used for sucrose feeding after the mosquitoes were fed infected blood. Natural bites from R. felis-infected An. gambiae were able to cause transient rickettsemias in mice, indicating that this mosquito species has the potential to be a vector of R. felis infection. This is particularly important given the recent report of high prevalence of R. felis infection in patients with “fever of unknown origin” in malaria-endemic areas.

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Multiple blood feeding in mosquitoes shortens the Plasmodium falciparum incubation period and increases malaria transmission potential

10.1101/2020.03.24.991356 ◽

2020 ◽

Author(s):

W. Robert Shaw ◽

Inga E. Holmdahl ◽

Maurice A. Itoe ◽

Kristine Werling ◽

Meghan Marquette ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Anopheles Gambiae ◽

Malaria Transmission ◽

Incubation Period ◽

Malaria Vector ◽

Blood Feeding ◽

Sub Saharan Africa ◽

Transmission Potential ◽

Sub Saharan ◽

Major Malaria Vector

AbstractMany mosquito species, including the major malaria vector Anopheles gambiae, naturally undergo multiple reproductive cycles of blood feeding, egg development and egg laying in their lifespan. Such complex mosquito behavior is regularly overlooked when mosquitoes are experimentally infected with malaria parasites, limiting our ability to accurately describe potential effects on transmission. Here, we examine how Plasmodium falciparum development and transmission potential is impacted when infected mosquitoes feed an additional time. We measured P. falciparum oocyst size and performed sporozoite time course analyses to determine the parasite’s extrinsic incubation period (EIP), i.e. the time required by parasites to reach infectious sporozoite stages, in An. gambiae females blood fed either once or twice. An additional blood feed at 3 days post infection drastically accelerates oocyst growth rates, causing earlier sporozoite accumulation in the salivary glands, thereby shortening the EIP (reduction of 2.25 ± 0.39 days). Moreover, parasite growth is further accelerated in transgenic mosquitoes with reduced reproductive capacity, which mimic genetic modifications currently proposed in population suppression gene drives. We incorporate our shortened EIP values into a measure of transmission potential, the basic reproduction number R0, and find the average R0 is remarkably higher (range: 10.1%–12.1% increase) across sub-Saharan Africa than when using traditional EIP measurements. These data suggest that malaria elimination may be substantially more challenging and that younger mosquitoes or those with reduced reproductive ability may provide a larger contribution to infection than currently believed. Our findings have profound implications for current and future mosquito control interventions.Significance StatementIn natural settings the female Anopheles gambiae mosquito, the major malaria vector, blood feeds multiple times in her lifespan. Here we demonstrate that an additional blood feed accelerates the growth of Plasmodium falciparum malaria parasites in this mosquito. Incorporating these data into a mathematical model across sub-Saharan Africa reveals that malaria transmission potential is likely to be substantially higher than previously thought, making disease elimination more difficult. Additionally, we show that control strategies that manipulate mosquito reproduction with the aim of suppressing Anopheles populations may inadvertently favor malaria transmission. Our data also suggest that parasites can be transmitted by younger mosquitoes, which are less susceptible to insecticide killing, with negative implications for the success of insecticide-based strategies.

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Multiple Mammarenaviruses Circulating in Angolan Rodents

Viruses ◽

10.3390/v13060982 ◽

2021 ◽

Vol 13 (6) ◽

pp. 982

Author(s):

Jana Těšíková ◽

Jarmila Krásová ◽

Joëlle Goüy de Bellocq

Keyword(s):

Geographical Area ◽

Sub Saharan Africa ◽

Virus Diversity ◽

High Prevalence ◽

Biogeographical Regions ◽

Sub Saharan ◽

Rodent Community ◽

High Virus ◽

Almost All ◽

Virus Genomes

Rodents are a speciose group of mammals with strong zoonotic potential. Some parts of Africa are still underexplored for the occurrence of rodent-borne pathogens, despite this high potential. Angola is at the convergence of three major biogeographical regions of sub-Saharan Africa, each harbouring a specific rodent community. This rodent-rich area is, therefore, strategic for studying the diversity and evolution of rodent-borne viruses. In this study we examined 290 small mammals, almost all rodents, for the presence of mammarenavirus and hantavirus RNA. While no hantavirus was detected, we found three rodent species positive for distinct mammarenaviruses with a particularly high prevalence in Namaqua rock rats (Micaelamys namaquensis). We characterised four complete virus genomes, which showed typical mammarenavirus organisation. Phylogenetic and genetic distance analyses revealed: (i) the presence of a significantly divergent strain of Luna virus in Angolan representatives of the ubiquitous Natal multimammate mouse (Mastomys natalensis), (ii) a novel Okahandja-related virus associated with the Angolan lineage of Micaelamys namaquensis for which we propose the name Bitu virus (BITV) and (iii) the occurrence of a novel Mobala-like mammarenavirus in the grey-bellied pygmy mouse (Mus triton) for which we propose the name Kwanza virus (KWAV). This high virus diversity in a limited host sample size and in a relatively small geographical area supports the idea that Angola is a hotspot for mammarenavirus diversity.

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High prevalence of Schistosoma haematobium × Schistosoma bovis hybrids in schoolchildren in Côte d'Ivoire

Parasitology ◽

10.1017/s0031182019001549 ◽

2019 ◽

Vol 147 (3) ◽

pp. 287-294 ◽

Cited By ~ 3

Author(s):

Etienne K. Angora ◽

Jean-François Allienne ◽

Olivier Rey ◽

Hervé Menan ◽

André O. Touré ◽

...

Keyword(s):

Cote D'ivoire ◽

Schistosoma Haematobium ◽

Côte D’Ivoire ◽

Sub Saharan Africa ◽

Cote D’Ivoire ◽

Mitochondrial Cox1 ◽

Fta Cards ◽

Côte D'ivoire ◽

High Prevalence ◽

Sub Saharan

AbstractSchistosomiasis is a neglected tropical disease, though it is highly prevalent in many parts of sub-Saharan Africa. While Schistosoma haematobium-bovis hybrids have been reported in West Africa, no data about Schistosoma hybrids in humans are available from Côte d'Ivoire. This study aimed to identify and quantify S. haematobium-bovis hybrids among schoolchildren in four localities of Côte d'Ivoire. Urine samples were collected and examined by filtration to detect Schistosoma eggs. Eggs were hatched and 503 miracidia were individually collected and stored on Whatman® FTA cards for molecular analysis. Individual miracidia were molecularly characterized by analysis of mitochondrial cox1 and nuclear internal transcribed spacer 2 (ITS 2) DNA regions. A mitochondrial cox1-based diagnostic polymerase chain reaction was performed on 459 miracidia, with 239 (52.1%) exhibiting the typical band for S. haematobium and 220 (47.9%) the S. bovis band. The cox1 and ITS 2 amplicons were Sanger sequenced from 40 randomly selected miracidia to confirm species and hybrids status. Among the 33 cox1 sequences analysed, we identified 15 S. haematobium sequences (45.5%) belonging to seven haplotypes and 18 S. bovis sequences (54.5%) belonging to 12 haplotypes. Of 40 ITS 2 sequences analysed, 31 (77.5%) were assigned to pure S. haematobium, four (10.0%) to pure S. bovis and five (12.5%) to S. haematobium-bovis hybrids. Our findings suggest that S. haematobium-bovis hybrids are common in Côte d'Ivoire. Hence, intense prospection of domestic and wild animals is warranted to determine whether zoonotic transmission occurs.

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Characterizing Permethrin and Etofenprox Resistance in Two Common Laboratory Strains of Anopheles gambiae (Diptera: Culicidae)

Insects ◽

10.3390/insects9040146 ◽

2018 ◽

Vol 9 (4) ◽

pp. 146 ◽

Cited By ~ 3

Author(s):

Aaron Gross ◽

Jeffrey Bloomquist

Keyword(s):

Anopheles Gambiae ◽

Pyrethroid Resistance ◽

Laboratory Strain ◽

Pyrethroid Insecticide ◽

Sub Saharan Africa ◽

Cross Resistance ◽

Type I ◽

Mosquito Vector ◽

Sub Saharan ◽

Anopheles Gambiae Giles

Anopheles gambiae Giles (Diptera: Culicidae) is the most prolific malaria vector in sub-Saharan Africa, where widespread insecticide resistance has been reported. An. gambiae laboratory strains are commonly used to study the basic biology of this important mosquito vector, and also in new insecticide discovery programs, where insecticide-susceptible and -resistant strains are often used to screen new molecules for potency and cross-resistance, respectively. This study investigated the toxicity of permethrin, a Type-I pyrethroid insecticide, and etofenprox, a non-ester containing pyrethroid insecticide, against An. gambiae at three life stages. This characterization was performed with susceptible (G3; MRA-112) and resistant (Akdr; MRA-1280) An. gambiae strains; the Akdr strain is known to contain the L1014F mutation in the voltage-sensitive sodium channel. Surprisingly, etofenprox displays a lower level of resistance than permethrin against all stages of mosquitoes, except in a headless larval paralysis assay designed to minimize penetration factors. In first-instar An. gambiae larvae, permethrin had significant resistance, determined by the resistance ratio (RR50 = 5), but etofenprox was not significantly different (RR50 = 3.4) from the wild-type strain. Fourth-instar larvae displayed the highest level of resistance for permethrin (RR50 = 108) and etofenprox (RR50 = 35). Permethrin (PC50 = 2 ppb) and etofenprox (PC50 = 9 ppb) resulted in headless larval paralysis (5-h), but resistance, albeit lower, was still present for permethrin (RR50 = 5) and etofenprox (RR50 = 6.9). In adult female mosquitoes, permethrin displayed higher resistance (RR50 = 14) compared to etofenprox (RR50 = 4.3). The level of etofenprox resistance was different from that previously reported for a similar Akron An. gambiae laboratory strain (MRA-913). The chemical synergists piperonyl butoxide (PBO) and diethyl maleate (DEM) were able to synergize permethrin, but not etofenprox in the resistant strain (Akdr). In conclusion, multiple mechanisms are likely involved in pyrethroid resistance, but resistance profiles are dependent upon selection. Etofenprox is an effective insecticide against An. gambiae in the lab but will likely suffer from resistance in the field.

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Prevalence of Anemia and Undernutrition of Adolescent Females in Selected Schools in Ghana

Journal of Nutrition and Metabolism ◽

10.1155/2021/6684839 ◽

2021 ◽

Vol 2021 ◽

pp. 1-5

Author(s):

Marina Aferiba Tandoh ◽

Abigail Owusuaa Appiah ◽

Anthony Kwaku Edusei

Keyword(s):

Public Health Problem ◽

Cross Sectional Study ◽

Adolescent Females ◽

Sub Saharan Africa ◽

Health And Wellness ◽

Cross Sectional ◽

High Prevalence ◽

Sub Saharan ◽

Poor Nutrition ◽

Prevalence Of Anemia

Anemia among adolescent females is a major worldwide public health problem which should be given appropriate attention. Half of all anemic cases are caused by iron deficiency. In addition to anemia, poor nutrition is also a challenge in sub-Saharan Africa. This study determined the prevalence of anemia and undernutrition among adolescent females in school. A cross-sectional study was conducted among 151 adolescent females in four basic schools in the Ahafo region of Ghana. The hemoglobin level and anthropometry measures of participants were taken to determine their anemic and nutritional status. The prevalence of anemia among adolescent females in school was 50.3%. Out of the 151 participants, 6.6%, 19.9%, and 23.8% were severely anemic, moderately anemic, or mildly anemic, respectively. Only 2% of the participants were underweight, but the rate of stunting was 26.5%. The notable high prevalence of anemia that was found among adolescent females was correlated with other health and wellness concerns. Anemia and under nutrition negatively affect academic performance, productivity, and general wellbeing of adolescents; therefore, effective measures should be put in place to correct and eradicate these nutritional problems.

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High prevalence of preventable infections in pregnancy in sub-Saharan Africa

Springer Healthcare News ◽

10.1007/s40014-012-0227-8 ◽

2012 ◽

Vol 1 (1) ◽

Keyword(s):

Sub Saharan Africa ◽

High Prevalence ◽

Sub Saharan ◽

In Pregnancy

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High-Prevalence Stunting in Preschool Children (1–5 Years) Attending Selected Health Centers in a Food Rich Area-Bushenyi District Southwestern Uganda

Journal of Nutrition and Metabolism ◽

10.1155/2021/5736864 ◽

2021 ◽

Vol 2021 ◽

pp. 1-6

Author(s):

Douglas Mugarura ◽

Herbert Izo Ninsiima ◽

Hellen Kinyi ◽

Ejike Daniel Eze ◽

Sam Tumwesigire ◽

...

Keyword(s):

Preschool Children ◽

Prevalence Ratio ◽

Cross Sectional Study ◽

Health Centers ◽

Sub Saharan Africa ◽

Cross Sectional ◽

High Prevalence ◽

Development Goals ◽

Chronic Undernutrition ◽

Sub Saharan

The prevalence of stunting among children in Uganda and Sub-Saharan Africa is still high, and if Uganda is to achieve the food-related Sustainable Development Goals (SDGs), it must urgently invest in improving nutrition and sanitation. In a food rich area like Bushenyi, chronic undernutrition could be due to several other factors than mere scarcity of food. The Objective(s). This study was carried out to determine the prevalence and socioclinical factors responsible for chronic undernutrition (stunting) among preschool children aged 1–5 years in selected Health facilities in Bushenyi district. Methodology. This was a cross-sectional study assessing the prevalence of stunting and its associated factors among children aged 1–5 years attending selected health centers in Bushenyi District. Data was collected using a pretested questionnaire, taking anthropometric measurements (height/length), and stool analysis for eggs of soil-transmitted helminthes. Prevalence of stunting was presented as percentages. Logistic regression with adjusted prevalence ratio was performed to test the association between the sociodemographic and clinical factors and stunting at bivariate levels of analysis. Results. Most of the children were female, with a median age of 2.1 years and resided in semiurban areas of Bushenyi with their parents. Prevalence of stunting was 89.3%. Only 10.7% of the children were infested with soil-transmitted helminthes. Children likely to be stunted were those who drank unboiled water and were exclusively breastfed. Conclusion. There is a high prevalence of chronic malnutrition in Bushenyi district associated with parents’/care takers’ low level of knowledge.

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Neurocysticercosis – A Journey from Pre-independence to Modern India

Annals of the National Academy of Medical Sciences (India) ◽

10.1055/s-0040-1712609 ◽

2016 ◽

Vol 52 (02) ◽

pp. 076-099

Author(s):

Gagandeep Singh ◽

Monika Singla

Keyword(s):

Indian Subcontinent ◽

Taenia Solium ◽

Population Based ◽

Sub Saharan Africa ◽

Ct Scans ◽

Common Finding ◽

Cns Involvement ◽

High Prevalence ◽

Endemic Areas ◽

Sub Saharan

ABSTRACTNeurocysticercosis (NCC) is infestation of the human brain by the larva of worm, Taenia solium and is the most prevalent central nervous system (CNS) helminthiasis. The disease is widespread in tropical and subtropical regions of the world, including the Indian subcontinent, China, Sub-Saharan Africa, Central and South America and contributes substantially to the burden of epilepsy in these areas(1) . CNS involvement is seen in 60-90% of systemic cysticercosis. About 2.5 million people worldwide are infected with T. solium, and antibodies to T. solium are seen in up to 25% of people in endemic areas(1-3) . A higher prevalence of epilepsy and seizures in endemic countries is partly because of a high prevalence of cysticercosis in these regions. Seizures are thought to be caused by NCC in as many as 30% of adult patients and in 51% of children in population based endemic regions (2) . About 12% of admissions to neurological services in endemic regions are attributed to NCC and nearly half a million deaths occurring annually worldwide can be attributed directly or indirectly to NCC (Bern et al.). Punctate calcific foci on CT scan are a very common finding in asymptomatic people residing in endemic areas, found in 14-20 % of CT scans. Both seizures and positive cysticercus serology are associated with the detection of cysticerci on CT scans. Seroprevalence using a recently developed CDC- based enzyme-linked immunotransfer blot (EITB) assay is estimated at 8-12% in Latin America and 4.9-24% in Africa and South-East Asia. It is estimated that 20 million people harbour neurocysticercosis worldwide(1) .

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