clay and Malaria

Surveillance of indoor and outdoor resting malaria vector populations is crucial to monitor possible changes in vector resting and feeding behaviours. This study was conducted to assess the resting behaviour, blood meal sources and circumsporozoite (CSP) rates of Anopheles mosquito in Aradum village, Northern Ethiopia.. Mosquito collection was conducted from September 2019 to February 2020 using clay pots (indoor and outdoor), pit shelter and pyrethrum spray catches (PSC). The species of Anopheles gambiae complex and Anopheles funestus group were identified using polymerase chain reaction (PCR). Enzyme-linked immunosorbent assay (ELISA) was done to determine CSP and blood meal sources of malaria vectors.. A total of 775 female Anopheles mosquitoes were collected using the clay pot, PSC and pit shelter. Seven Anopheles mosquito species were identified morphologically, of which Anopheles demeilloni (593; 76.5%) was the dominant species followed by An. funestus group (73; 9.4%). Seventy-three An. funestus group screened by PCR, 91.8% (67/73) were identified as Anopheles leesoni and only 2.7% (2/73) were found to be Anopheles parensis. The molecular speciation of 71 An. gambiae complex confirmed 91.5% (65/71) of Anopheles arabiensis. The majority of Anopheles mosquitoes were collected from outdoor pit shelter (42.2%) followed by outdoor clay pots. The majority of the blood meal of An. demeilloni (57.5%; 161/280), An. funestus sensu lato 10 (43.5%) and An. gambiae (33.3%; 14/42) originated from bovine. None of the 364 Anopheles mosquitoes tested for Plasmodium falciparum and Plasmodium vivax sporozoite infections were positive.. Since the Anopheles mosquitoes in the area prefer to bite cattle, it may be best to target them with an animal-based intervention. Clay pots could be an alternative tool for outdoor monitoring of malaria vectors in areas where pit shelter construction is not possible.

Topics: Animals; Anopheles; Cattle; Clay; Ethiopia; Female; Malaria; Malaria, Vivax; Mosquito Vectors; Protozoan Proteins

Anopheles funestus, the main malaria vector, prefer to oviposit in permanent and/or semi-permanent breeding habitats located far from human dwellings. Difficulties in identifying and accessing these habitats jeopardize the feasibility of conventional larviciding. In this way, a semi-field study was conducted to assess the potential of autodissemination of pyriproxyfen (PPF) by An. funestus for its control.. The study was conducted inside a semi-field system (SFS). Therein, two identical separate chambers, the treatment chamber with a PPF-treated clay pot (0.25 g AI), and the control chamber with an untreated clay pot. In both chambers, one artificial breeding habitat made of a plastic basin with one litre of water was provided. Three hundred blood-fed female An. funestus aged 5-9 days were held inside untreated and treated clay pots for 30 min and 48 h before being released for oviposition. The impact of PPF on adult emergence, fecundity, and fertility through autodissemination and sterilization effects were assessed by comparing the treatment with its appropriate control group.. Mean (95% CI) percentage of adult emergence was 15.5% (14.9-16.1%) and 70.3% (69-71%) in the PPF and control chamber for females exposed for 30 min (p < 0.001); and 19% (12-28%) and 95% (88-98%) in the PPF and control chamber for females exposed for 48 h (p < 0.001) respectively. Eggs laid by exposed mosquitoes and their hatch rate were significantly reduced compared to unexposed mosquitoes (p < 0.001). Approximately, 90% of females exposed for 48 h retained abnormal ovarian follicles and only 42% in females exposed for 30 min.. The study demonstrated sterilization and adult emergence inhibition via autodissemination of PPF by An. funestus. Also, it offers proof that sterilized An. funestus can transfer PPF to prevent adult emergence at breeding habitats. These findings warrant further assessment of the autodissemination of PPF in controlling wild population of An. funestus, and highlights its potential for complementing long-lasting insecticidal nets.

Topics: Adult; Animals; Anopheles; Clay; Female; Humans; Malaria; Mosquito Vectors

Plasmodium vivax was endemic in northern Europe until the early twentieth century. Considering climate change and the recent emergence of other vector borne diseases in Europe, historical insight into the relationship between malaria and environmental factors in northern Europe is needed. This article describes malaria epidemiology in late-nineteenth century Denmark.. We described the seasonality and spatial patterns of malaria, and the relationship of the disease with environmental factors such as soil types, clay content and elevation for the period 1862-1914. We studied demographic and seasonal patterns and malaria mortality in the high-morbidity period of 1862-1880. Finally, we studied the relationship between malaria seasonality and temperature and precipitation using a Spearman correlation test.. We found that the highest incidence occurred in eastern Denmark. Lolland-Falster medical region experienced the highest incidence (14.5 cases per 1000 pop.) and Bornholm medical region experienced the lowest incidence (0.57 cases per 1000 pop.). Areas with high malaria incidence also had high soil clay content, high agricultural production, and Lolland-Falster furthermore has a low elevation. Malaria incidence typically peaked in May and was associated with high temperatures in July and August of the previous year but not with precipitation. The case fatality rate was 0.17%, and the disease affected both sexes and all age groups except for infants. In 1873, a large epidemic occurred following flooding from a storm surge in November 1872.. Malaria gradually declined in Denmark during our study period and had essentially disappeared by 1900. The high adult and low child morbidity in 1862-1880 indicates that malaria was not highly endemic in this period, as malaria is most frequent among children in highly endemic areas today. The association of high malaria incidence in spring with warmer temperatures in the previous summer suggests that transmission took place in the previous summers. The close geographical connection between malaria and soil types, agricultural production and elevation suggests that these factors are detrimental to sustain endemic malaria. Our findings of a close connection between malaria and environmental factors such as climate and geography provides insights to address potential reintroduction of malaria in temperate climates.

Topics: Adult; Child; Clay; Denmark; Female; Humans; Incidence; Malaria; Malaria, Vivax; Male; Plasmodium vivax; Soil