Impact of Mosquito Bites on Asexual Parasite Density and Gametocyte Prevalence in Asymptomatic Chronic Plasmodium falciparum Infections and Correlation with IgE and IgG Titers

Lawaly, Ramatoulaye; Konaté, Lassana; Marrama, Laurence; Dia, Ibrahima; Diallo, Diawo; Sarr, Fatoumata Diène; Schneider, Bradley S.; Casadémont, Isabelle; Diallo, Mawlouth; Brey, Paul T.; Sakuntabhai, Anavaj; Mécheri, Salaheddine; Rácz, Paul

doi:10.1128/iai.06414-11

Cited by 25 publications

(31 citation statements)

References 54 publications

(43 reference statements)

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“…falciparum gametocytes [3,9,57,58]. For example, a longitudinal study in Burkina Faso found that season is an independent determinant of gametocyte prevalence and density and that it is significantly higher in the wet season compared to the dry season [9].…”

Section: Discussionmentioning

confidence: 99%

Associations between Season and Gametocyte Dynamics in Chronic Plasmodium falciparum Infections

et al. 2016

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IntroductionIn a markedly seasonal malaria setting, the transition from the transmission-free dry season to the transmission season depends on the resurgence of the mosquito population following the start of annual rains. The sudden onset of malaria outbreaks at the start of the transmission season suggests that parasites persist during the dry season and respond to either the reappearance of vectors, or correlated events, by increasing the production of transmission stages. Here, we investigate whether Plasmodium falciparum gametocyte density and the correlation between gametocyte density and parasite density show seasonal variation in chronic (largely asymptomatic) carriers in eastern Sudan.Materials and MethodsWe recruited and treated 123 malaria patients in the transmission season 2001. We then followed them monthly during four distinct consecutive epidemiological seasons: transmission season 1, transmission-free season, pre-clinical period, and transmission season 2. In samples collected from 25 participants who fulfilled the selection criteria of the current analysis, we used quantitative PCR (qPCR) and RT-qPCR to quantify parasite and gametocyte densities, respectively.Results and DiscussionWe observed a significant increase in gametocyte density and a significantly steeper positive correlation between gametocyte density and total parasite density during the pre-clinical period compared to the preceding transmission-free season. However, there was no corresponding increase in the density or prevalence of total parasites or gametocyte prevalence. The increase in gametocyte production during the pre-clinical period supports the hypothesis that P. falciparum may respond to environmental cues, such as mosquito biting, to modulate its transmission strategy. Thus, seasonal changes may be important to ignite transmission in unstable-malaria settings.

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Section: Discussionmentioning

confidence: 99%

Associations between Season and Gametocyte Dynamics in Chronic Plasmodium falciparum Infections

et al. 2016

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“…There was no evidence of antiparasite IgE in this cohort of children. We previously showed that circulating antiparasite IgE titres were strongly positively correlated with antimosquito saliva IgE, but became undetectable following malaria exposure, potentially being bound to effector cells 33. Only mosquito saliva, a known major local allergen, induced a specific IgE response at significantly higher titres in individuals with atopic dermatitis.…”

Section: Discussionmentioning

confidence: 99%

“…Specific IgE titres were measured by ELISA as previously described 33. A panel of allergens of potential pertinence to the three classes of allergy was used: (1) salivary gland extracts (SGE) of two mosquito species present in the study cohorts, Aedes aegypti and Anopheles gambiae sensu stricto and (2) P falciparum parasite extract were prepared as previously described31; (3) House dust mite spp.…”

Section: Methodsmentioning

confidence: 99%

“…Allergy classes were reduced to two levels, severe or moderate vs none for analyses of asthma, atopic dermatitis and allergic rhinoconjunctivitis and high probability vs probable and unlikely for atopic tendency. Covariables included sickle cell trait33 gender, number of days present on site during the trimester, trimestrial incidence of P falciparum and age. Age was initially analysed as a continuous covariate.…”

Section: Methodsmentioning

confidence: 99%

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Asthma and atopic dermatitis are associated with increased risk of clinicalPlasmodium falciparummalaria

et al. 2013

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ObjectivesTo assess the impact of atopy and allergy on the risk of clinical malaria.DesignA clinical and immunological allergy cross-sectional survey in a birth cohort of 175 children from 1 month to 14 years of age followed for up to 15 years in a longitudinal open cohort study of malaria in Senegal. Malaria incidence data were available for 143 of these children (aged 4 months to 14 years of age) for up to 15 years. Mixed-model regression analysis was used to determine the impact of allergy status on malaria incidence, adjusting for age, gender, sickle-cell trait and force of infection.Main outcome measuresAsthma, allergic rhinoconjunctivitis and atopic dermatitis status, the number of clinical Plasmodium falciparum malaria episodes since birth and associated parasite density.Results12% of the children were classified as asthmatic and 10% as having atopic dermatitis. These groups had respectively a twofold (OR 2.12 95%; CI 1.46 to 3.08; p=8×10−5) and threefold (OR 3.15; 1.56 to 6.33; p=1.3×10−3) increase in the risk of clinical P falciparum malaria once older than the age of peak incidence of clinical malaria (3–4 years of age). They also presented with higher P falciparum parasite densities (asthma: mean 105.3 parasites/μL±SE 41.0 vs 51.3±9.7; p=6.2×10−3. Atopic dermatitis: 135.4±70.7 vs 52.3±11.0; p=0.014). There was no effect of allergy on the number of non-malaria clinical presentations. Individuals with allergic rhinoconjunctivitis did not have an increased risk of clinical malaria nor any difference in parasite densities.ConclusionsThese results demonstrate that asthma and atopic dermatitis delay the development of clinical immunity to P falciparum. Despite the encouraging decrease in malaria incidence rates in Africa, a significant concern is the extent to which the increase in allergy will exacerbate the burden of malaria. Given the demonstrated antiparasitic effect of antihistamines, administration to atopic children will likely reduce the burden of clinical malaria in these children, increase the efficacy of first-line treatment antimalarials and alleviate the non-infectious consequences of atopy.

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“…44,45 If silica particles truly have such a dramatic effect on sporozoite invasion, on drug efficacy, on infected erythrocytes and on gametocytes one may wonder why all the laboratories desperately looking for a solution to the alarming malaria catastrophy ignored this possibility. May be because all studies are based on in vitro efficiencies of potential antimalarials against parasites.…”

Section: Resultsmentioning

confidence: 99%

Silica particles inhibit sporozoite invasion, promote IgE, inhibit CYP3A4 and provoke bursting of infected erythrocytes

Lutgen¹

2018

PPIJ

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Silica may boost the immune system and stimulate IgE production. This effect is known since 40 years. IgE is probably the most important item in acquired humoral activity against malaria.2-7 A single dose of standard quartz with particle size <5μm is able to stimulate in Balb/c mice the production of IgE and IgG1 antibody. Silica in plants and in ArtemisiaThis mineral has barely been studied in plants. Plants take up silicon as mono-silicic acid and later it is deposited in its polymerized form as amorphous hydrated silica. Major silica depositions occur in root endodermis, leaf epidermal cells and trichomes. The ability of a plant to accumulate Si varies greatly between species. It is up to 2% in wheat, rice, oats, close to 0 % in flowers, and intermediate in kitchen and medicinal herbs: 0.4 % in spinach, 0,1 in ginseng, 0.32%, in parsley, 0.56 in salvia, 0,56 in tilia, 0.26 % in dill, 0,67 in inula, 0,6 in hibiscus, 0.61% in mint, 0.35% in Artemisia annua, 0.22% in Artemisia absinthium, 0.57% in Artemisia frigida, but only 0.002% in Artemisia maritima. Horsetail (Equisetum arvense) and nettle (Urtica dioica) containing 1.1% silica were used in Europe against malaria. [9][10][11][12][13] In many plants silica is present in the form of phytoliths in cell walls for their strenghtening. Families with high phytolith production are Acanthaceae, Aceraceae, Annonaceae, Asteraceae, Artemisia tridentata and Artemisia spicata for example contain phytoliths.

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Impact of Mosquito Bites on Asexual Parasite Density and Gametocyte Prevalence in Asymptomatic Chronic Plasmodium falciparum Infections and Correlation with IgE and IgG Titers

Cited by 25 publications

References 54 publications

Associations between Season and Gametocyte Dynamics in Chronic Plasmodium falciparum Infections

Associations between Season and Gametocyte Dynamics in Chronic Plasmodium falciparum Infections

Asthma and atopic dermatitis are associated with increased risk of clinicalPlasmodium falciparummalaria

Silica particles inhibit sporozoite invasion, promote IgE, inhibit CYP3A4 and provoke bursting of infected erythrocytes

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