Review of Issues on Residual Malaria Transmission.

Residual malaria transmission is the actual maintained inoculation of Plasmodium, in spite of a well-designed and implemented vector control programs, and is of great concern for malaria elimination. Residual malaria transmission occurs under several possible circumstances, among which the presence of exophilic vector species, such as Anopheles dirus, or indoor- and outdoor-biting vectors, such as Anopheles nili, or specific behavior, such as feeding on humans indoors, then resting or leaving the house the same night (such as Anopheles moucheti) or also changes in behavior induced by insecticides applied inside houses, such as the well-known deterrent effect of permethrin-treated nets or the irritant effect of DDT. The use of insecticides may change the composition of local Anopheles populations, such as A.

Coalition: Advocacy for prospective clinical trials to test the post-exposure potential of hydroxychloroquine against COVID-19.

Our coalition of public health experts, doctors, and scientists worldwide want to draw attention to the need for high-quality evaluation protocols of the potential beneficial effect of hydroxychloroquine (HCQ) as a post-exposure drug for exposed people. In the absence of an approved, recognized effective pre or post-exposure prophylactic drug or vaccine for COVID-19, nor of any approved and validated therapeutic drug, coupled with social and political pressure raised by publicity both regarding the potential beneficial effect of hydroxychloroquine (HCQ) as well as potential risks from HCQ, we urge the immediate proper clinical trials. Specifically, we mean using HCQ for post-exposure of people with close contact with patients with positive COVID19 rtPCR, including home and medical caregivers.

Insecticide-Treated Mosquito Nets.

The coherent and coordinated strategy put in place since the beginning of the century to fight malaria has led to a significant reduction in the global burden of the disease. Of the various elements composing this strategy, it appears that vector control and, in the first place, the massive distribution of LLIN (long-lasting impregnated nets) have contributed significantly to this success. The idea, a priori trivial, of impregnating nets with insecticide to make them more effective, emerged in the late 1980s in Benin.

Malaria overdiagnosis and subsequent overconsumption of antimalarial drugs in Angola: Consequences and effects on human health.

Microscopic blood smear examinations done in health centers of Angola demonstrated a large overdiagnosis of malaria cases with an average rate of errors as high as 85%. Overall 83% of patients who received Coartem had an inappropriate treatment. Overestimated malaria diagnosis was noticed even when specific symptoms were part of the clinical observation, antimalarial treatments being subsequently given.

Spatio-temporal variations of Anopheles coluzzii and An. gambiae and their Plasmodium infectivity rates in Lobito, Angola.

From 2003 to 2007, entomological surveys were conducted in Lobito town (Benguela Province, Angola) to determine which Anopheles species were present and to identify the vectors responsible for malaria transmission in areas where workers of the Sonamet Company live. Two types of surveys were conducted: (1) time and space surveys in the low and upper parts of Lobito during the rainy and dry periods; (2) a two-year longitudinal study in Sonamet workers' houses provided with long-lasting insecticide-treated nets (LLIN), "PermaNet," along with the neighboring community. Both species, An.

Pilot study on the combination of an organophosphate-based insecticide paint and pyrethroid-treated long lasting nets against pyrethroid resistant malaria vectors in Burkina Faso.

A pilot study to test the efficacy of combining an organophosphate-based insecticide paint and pyrethroid-treated Long Lasting Insecticide Treated Nets (LLINs) against pyrethroid-resistant malaria vector mosquitoes was performed in a real village setting in Burkina Faso. Paint Inesfly 5A IGR™, comprised of two organophosphates (OPs) and an Insect Growth Regulator (IGR), was tested in combination with pyrethroid-treated LLINs. Efficacy was assessed in terms of mortality for 12 months using Early Morning Collections of malaria vectors and 30-minute WHO bioassays.

Molecular epidemiology of drug-resistant Plasmodium falciparum in Benguela province, Angola.

Background: The malaria situation has been worsening in Angola, partly due to armed conflict until the recent past and drug-resistant Plasmodium falciparum. Malaria transmission is heterogeneous within the country, and data on drug-resistant malaria in different parts of the country are incomplete. The aim of the present study was to evaluate resistance to 4-aminoquinolines and antifolate drugs in P.

The Anopheles gambiae cE5 salivary protein: a sensitive biomarker to evaluate the efficacy of insecticide-treated nets in malaria vector control.

Evaluation of vector control is crucial for improving malaria containment and, according to World Health Organization, new complementary indicators would be very valuable. In this study the IgG response to the Anopheles-specific cE5 salivary protein was tested as a tool to evaluate the efficacy of insecticide-treated nets in reducing human exposure to malaria vectors. Sera collected during a longitudinal study carried out in Angola, and including entomological and parasitological data, were used to assess the IgG response to the Anopheles gambiae cE5 in both children and adults, before and after the application of insecticide-treated nets.

Proposed use of spatial mortality assessments as part of the pesticide evaluation scheme for vector control.

Background: The WHO Pesticide Evaluation Scheme to evaluate the efficacy of insecticides does not include the testing of a lethal effect at a distance. A tool was developed to evaluate the spatial mortality of an insecticide product against adult mosquitoes at a distance under laboratory and field conditions. Operational implications are discussed.

Inland valley rice production systems and malaria infection and disease in the forest region of western Côte d'Ivoire.

Background: This study aimed to determine the epidemiological impact of rice cultivation in inland valleys on malaria in the forest region of western Côte d'Ivoire. The importance of malaria was compared in terms of prevalence and parasite density of infections and also in terms of clinical malaria incidence between three agro-ecosystems: (i) uncultivated inland valleys, (R0), (ii) inland valleys with one annual rice cultivation in the rainy season, (R1) and (iii) developed inland valleys with two annual rice cultivation cycles, (R2).

Methods: Between May 1998 and March 1999, seven villages of each agro-ecosystem (R0, R1 and R2) were randomly selected among villages pooled by farming system.

Insecticide-treated plastic sheeting for emergency malaria prevention and shelter among displaced populations: an observational cohort study in a refugee setting in Sierra Leone.

A double-blind phase III malaria prevention trial was conducted in two refugee camps using pre-manufactured insecticide-treated plastic sheeting (ITPS) or untreated polyethylene sheeting (UPS) randomly deployed to defined sectors of each camp. In Largo camp the ITPS or UPS was attached to inner walls and ceilings of shelters, whereas in Tobanda the ITPS or UPS was used to line only the ceiling and roof. In Largo the Plasmodium falciparum incidence rate in children up to 3 years of age who were cleared of parasites and monitored for 8 months was 163/100 person-years under UPS and 63 under ITPS (adjusted odds ratio [AOR] = 0.

Multiple independent introductions of Plasmodium falciparum in South America.

The origin of Plasmodium falciparum in South America is controversial. Some studies suggest a recent introduction during the European colonizations and the transatlantic slave trade. Other evidence--archeological and genetic--suggests a much older origin.

Efficacy of an insecticide paint against malaria vectors and nuisance in West Africa--part 2: field evaluation.

Background: Widespread resistance of the main malaria vector Anopheles gambiae to pyrethroids reported in many African countries and operational drawbacks to current IRS methods suggest the convenience of exploring new products and approaches for vector control. Insecticide paint Inesfly 5A IGR™, containing two organophosphates (OPs), chlorpyrifos and diazinon, and one insect growth regulator (IGR), pyriproxyfen, was tested in Benin, West Africa, for 12 months.

Methods: Field trials were conducted in six experimental huts that were randomly allocated to one or two layers of insecticide at 1 Kg/6 m2 or control.

Efficacy of an insecticide paint against insecticide-susceptible and resistant mosquitoes - part 1: laboratory evaluation.

Background: The main malaria vector Anopheles gambiae and the urban pest nuisance Culex quinquefasciatus are increasingly resistant to pyrethroids in many African countries. There is a need for new products and strategies. Insecticide paint Inesfly 5A IGR™, containing two organophosphates (OPs), chlorpyrifos and diazinon, and insect growth regulator (IGR), pyriproxyfen, was tested under laboratory conditions for 12 months following WHOPES Phase I procedures.

Effectiveness of permanet in Côte d'Ivoire rural areas and residual activity on a knockdown-resistant strain of Anopheles gambiae.

The effectiveness of long-lasting preimpregnated nets of Permanet type (deltamethrin, 50 mg/m2) erected in households in rural areas of Côte d'Ivoire was tested on two laboratory strains of Anopheles gambiae s.s.: the Kisumu susceptible strain and the Vk per pyrethroids resistant strain with >70% kdr allelic frequency.

Evaluation of synthetic repellents on mosquito nets in experimental huts against insecticide-resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes.

Owing to the development of pyrethroid resistance in Anopheles gambiae, there is a need to develop chemical alternatives for use on mosquito nets. Synthetic insect repellents are widely used for personal protection as skin or clothing applications. The efficacy of repellent-treated nets (RTN) was evaluated in experimental huts in Côte d'Ivoire against pyrethroid-resistant populations of An.

Protective efficacy of lambda-cyhalothrin treated nets in Anopheles gambiae pyrethroid resistance areas of Côte d'Ivoire.

The efficacy of nets treated with lambda-cyhalothrin, a pyrethroid insecticide, on malaria infection and disease was assessed for the first time at the community level in Anopheles gambiae pyrethroid resistance areas. The study was carried out in northern Côte d'Ivoire, which is an area of kdr resistance. Four pairs of villages were selected and matched according to demographic, sociological, and ecological criteria.

Combating malaria vectors in Africa: current directions of research.

Vector control remains an important component of malaria control, particularly in Africa where most infant deaths occur. Among the different methods, insecticide-treated bednets seem to be a suitable way to reduce morbidity and child mortality in endemic areas. To facilitate their large-scale use and to investigate alternative vector control methods, the authors propose these current directions of research that are already being explored in Africa through a collaborating network involving several African countries: (1) vector genetics, (2) insecticide resistance and (3) vector control strategies.