dieldrin and Malaria--Falciparum

Although malaria is endemic in some areas of southeastern Iran, following the successful national malaria elimination plan, the local transmission area has been shrunk. The main cases in Iran are due to Plasmodium vivax followed by P. falciparum. This study was aimed to determine the current situation of malaria in Kerman Province of Iran and evaluate the insecticide resistance of main vectors. The field study was conducted in 2019. Data of new malaria cases were obtained from the health centers for the period of 2009-2018. Susceptibility status of Anopheles stephensi and An. dthali was evaluated against dichlorodiphenyltrichloroethane, Dieldrin, Malathion, Bendiocarb, Deltamethrin, and Temephos at the diagnostic dose. A total of 522 malaria cases were recorded and divided into indigenous (33.14%) and imported (66.86%) categories. The highest incidence of the disease was reported from the southern areas of the province, where all indigenous cases occurred. Adults of An. stephensi were resistant to dichlorodiphenyltrichloroethane while its resistance to be confirmed to dieldrin, bendiocarb and deltamethrin. As An. dthali had less than 98% mortality against bendiocarb, the resistance status should be confirmed with more tests. Our findings showed both species had less than 98% mortality against bendiocarb and deltamethrin insecticides which are used in malaria vector control program in Iran. Due to the susceptibility of these vectors to temephos, larviciding can be advised for vector control in this area.

Topics: Animals; Anopheles; DDT; Dieldrin; Insecticide Resistance; Insecticides; Iran; Malaria; Malaria, Falciparum; Mosquito Vectors; Pyrethrins; Temefos; World Health Organization

During five years, from 1953, a village scale indoors residual spraying (IRS) was done in the pilot zone of Bobo-Dioulasso, Burkina Faso, with DDT or dieldrin (DLN) or even HCH with a conceptually both entomological and parasitological evaluation [18].Compared to the control area, DDT induced an approximatively 95% and 67% reduction in the landing rate of

Topics: Animals; Anopheles; Child; DDT; Dieldrin; Humans; Infant; Infant, Newborn; Insecticides; Malaria; Malaria, Falciparum; Mosquito Control; Mosquito Vectors; Plasmodium; Sporozoites

Growing problems of pyrethroid resistance in Anopheles funestus have intensified efforts to identify alternative insecticides. Many agrochemicals target the GABA receptors, but cross-resistance from dieldrin resistance may preclude their introduction. Dieldrin resistance was detected in An. funestus populations from West (Burkina Faso) and central (Cameroon) Africa, but populations from East (Uganda) and Southern Africa (Mozambique and Malawi) were fully susceptible to this insecticide. Partial sequencing of the dieldrin target site, the γ-aminobutyric acid (GABA) receptor, identified two amino acid substitutions, A296S and V327I. The A296S mutation has been associated with dieldrin resistance in other species. The V327I mutations was detected in the resistant sample from Burkina Faso and Cameroon and consistently associated with the A296S substitution. The full-length of the An. funestus GABA-receptor gene, amplified by RT-PCR, generated a sequence of 1674 bp encoding 557 amino acid of the protein in An. funestus with 98% similarity to that of Anopheles gambiae. Two diagnostic assays were developed to genotype the A296S mutation (pyrosequencing and PCR-RFLP), and use of these assays revealed high frequency of the resistant allele in Burkina Faso (60%) and Cameroon (82%), moderate level in Benin (16%) while low frequency or absence of the mutation was observed respectively in Uganda (7.5%) or 0% in Malawi and Mozambique. The distribution of the Rdl(R) mutation in An. funestus populations in Africa suggests extensive barriers to gene flow between populations from different regions.

Topics: Africa; Alleles; Amino Acid Sequence; Animals; Anopheles; Base Sequence; Dieldrin; Genotype; Insect Control; Insect Vectors; Insecticide Resistance; Insecticides; Malaria, Falciparum; Molecular Sequence Data; Mutation; Phylogeography; Plasmodium falciparum; Polymorphism, Restriction Fragment Length; Protein Binding; Receptors, GABA; Reverse Transcriptase Polymerase Chain Reaction; Sequence Analysis, DNA

We reviewed the use of simple mathematical models to estimate the duration of Plasmodium falciparum infection after transmission has been interrupted. We then fit an exponential decay model to repeated cross-sectional survey data collected from three historical trials of indoor residual spraying against malaria: one from two contiguous districts in Tanzania-Kenya (Pare Taveta) carried out in 1954, the others in West Papua (1953), and the Garki project in northern Nigeria (1972-1973). A cross-sectional analysis of these datasets gave overall estimates of 602 days (95% confidence interval [CI] = 581-625) for the infection duration in Pare Taveta, 734 days (95% CI = 645-849) in West Papua, and 1,329 days (95% CI =1,193-1,499) for Garki. These estimates are much greater than the most widely quoted figures for the duration of untreated P. falciparum infections. Although these may be exaggerated because some reinfections occurred despite intensive vector control, prevalence was still decreasing when all these projects ended. Longitudinal survival analysis of the Garki data gave much shorter estimates of duration (186 days, 95% CI = 181-191), but effects of imperfect detection of parasites by microscopy severely bias these estimates. Estimates of infection duration for different age groups showed considerable variation but no general age trend. There was also no clear relationship between malaria endemicity and infection duration. Analyses of successive sampling from the same individuals with parasite typing are needed to obtain more reliable estimates of infection duration in endemic areas. Periods of several years may be required to evaluate long-term effects of interventions on malaria prevalence.

Topics: Animals; Cross-Sectional Studies; DDT; Dieldrin; Housing; Humans; Insecticides; Kenya; Malaria, Falciparum; Models, Biological; Mosquito Control; Nigeria; Papua New Guinea; Plasmodium falciparum; Prevalence; Tanzania