Lighting and ventilation effects of Anopheles arabicans entering homes using light trap trials in Tanzania: Experimental Cabin Research Malaria Journal

In sub-Saharan Africa, home design and ventilation can influence the number of malaria-carrying mosquitoes entering a home. This study hypothesized that interior light from a CDC light trap (visible from outside the cabin) would increase the entry of Anopheles arabinis, an important malaria vector, and examined whether ventilation reverses this effect.
Four occupied experimental houses, each located in a large room, were used to evaluate how light and ventilation affect the number of mosquitoes entering the houses in Tanzania. Every night 300 laboratory-bred female Anns. arabiensis were released into each room for 72 nights. Night collection of mosquitoes was carried out using light traps placed indoors. Use a data logger to measure temperature and carbon dioxide concentration. Treatment and sleeping quarters alternated between cabins using a randomized block design.
When indoor light was visible outside the huts, there was an 84% increase in the odds of collecting mosquitoes indoors (Odds ratio, OR = 1.84, 95% confidence intervals, 95% CI 1.74–1.95, p < 0.001) compared with when it was not. When indoor light was visible outside the huts, there was an 84% increase in the odds of collecting mosquitoes indoors (Odds ratio, OR = 1.84, 95% confidence intervals, 95% CI 1.74–1.95, p < 0.001) compared with when it was not. Когда внутренний свет был виден за пределами хижины, вероятность сбора комаров в помещении увеличивалась на 84 % (отношение шансов, ОШ = 1,84, 95 % доверительные интервалы, 95 % ДИ 1,74–1,95, р < 0,001) по сравнению с тем, когда он не было. When interior light was visible outside the hut, the likelihood of indoor mosquito collection increased by 84% (odds ratio, OR = 1.84, 95% confidence intervals, 95% CI 1.74–1.95, p < 0.001) compared to with when he wasn’t.当室内光线在小屋外可见时,在室内收集蚊子的几率增加了84%(优势比,OR = 1.84,95% 置信区间,95% CI 1.74–1.95,p < 0.001)。当 室内 光线 在 小 屋 外 见 时 , 在 室内 蚊子 的 几率 增加 了 了 了 84% (比 , , , , , , , , , , , , , , , , , 置信 , 95% Ci 1.74–1.95 , p <0.001)。。。)))))))))) Вероятность сбора комаров в помещении увеличивалась на 84 %, когда внутренний свет был виден за пределами кабины (отношение шансов, ОШ = 1,84, доверительный интервал 95 %, 95 % ДИ 1,74–1,95, р < 0,001). The likelihood of indoor mosquito collection increased by 84% when interior light was visible outside the cabin (odds ratio, OR = 1.84, 95% CI, 95% CI 1.74–1.95, p < 0.001). no. Although the odds of collecting mosquitoes in huts with closed eaves (OR = 0.54, 95% CI 0.41–0.72, p < 0.001) was less than those with open eaves, few mosquitoes entered either type of well-ventilated hut. Although the odds of collecting mosquitoes in huts with closed eaves (OR = 0.54, 95% CI 0.41–0.72, p < 0.001) was less than those with open eaves, few mosquitoes entered either type of well-ventilated hut. Хотя вероятность сбора комаров в хижинах с закрытыми крышами (ОШ = 0,54, 95% ДИ 0,41–0,72, p <0,001) была меньше, чем в хижинах с открытыми крышами, мало комаров проникало в хорошо вентилируемые хижины любого типа. Although the probability of gathering mosquitoes in closed-roof huts (OR = 0.54, 95% CI 0.41–0.72, p < 0.001) was less than in open-roof huts, few mosquitoes entered well-ventilated huts of any type. .尽管在封闭屋檐的小屋中收集蚊子的几率(OR = 0.54, 95% CI 0.41–0.72, p < 0.001)低于开放屋檐的小屋,但很少有蚊子进入任何一种通风良好的小屋。尽管 在 封闭 屋檐 的 小 屋 收集 蚊子 的 几 (((or = 0.54, 95% Ci 0.41–0.72, p <0.001) 开放 屋檐 的 屋 但 很少 有 蚊子 进入 任何 一 通风 良好 小。。 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋 屋A Немногие комары проникали в хорошо проветриваемые хижины любого типа, хотя вероятность сбора комаров в хижинах с закрытыми крышами (OR = 0,54, 95% ДИ 0,41–0,72, p <0,001) была ниже, чем в хижинах с открытыми крышами. Few mosquitoes entered well-ventilated huts of any type, although the likelihood of collecting mosquitoes in huts with closed roofs (OR = 0.54, 95% CI 0.41–0.72, p < 0.001) was lower than in huts with open roofs . The odds of collecting mosquitoes was 99% less in well-ventilated huts, compared with poorly-ventilated traditional huts (OR = 0.01, 95% CI 0.01–0.03, p < 0.001). The odds of collecting mosquitoes was 99% less in well-ventilated huts, compared with poorly-ventilated traditional huts (OR = 0.01, 95% CI 0.01–0.03, p < 0.001). Вероятность сбора комаров была на 99% меньше в хорошо проветриваемых хижинах по сравнению с плохо вентилируемыми традиционными хижинами (ОШ = 0,01, 95% ДИ 0,01–0,03, р <0,001). The likelihood of mosquito collection was 99% less in well-ventilated huts compared to poorly ventilated traditional huts (OR = 0.01, 95% CI 0.01–0.03, p<0.001).与通风不良的传统小屋相比,在通风良好的小屋中收集蚊子的几率要低99%(OR = 0.01, 95% CI 0.01–0.03, p < 0.001)。 99%(OR = 0.01,95% CI 0.01–0.03, p<0.03 Вероятность сбора комаров была на 99% ниже в хорошо проветриваемых хижинах, чем в плохо вентилируемых обычных хижинах (ОШ = 0,01, 95% ДИ 0,01–0,03, р <0,001). The likelihood of mosquito collection was 99% lower in well-ventilated huts than in poorly ventilated conventional huts (OR = 0.01, 95% CI 0.01–0.03, p<0.001). In well-ventilated huts, indoor temperatures were 1.3 °C (95% CI 0.9–1.7, p < 0.001) cooler, with lower carbon dioxide (CO2) levels (mean difference = 97 ppm, 77.8–116.2, p < 0.001) than in poorly-ventilated huts. In well-ventilated huts, indoor temperatures were 1.3 °C (95% CI 0.9–1.7, p < 0.001) cooler, with lower carbon dioxide (CO2) levels (mean difference = 97 ppm, 77.8–116.2, p < 0.001) than in poorly ventilated huts. В хорошо проветриваемых хижинах температура в помещении была на 1,3 °C (95% ДИ 0,9–1,7, p < 0,001) ниже, с более низким уровнем углекислого газа (CO2) (средняя разница = 97 частей на миллион, 77,8–116,2, p < 0,001), чем в плохо проветриваемых бараках. In well-ventilated huts, indoor temperatures were 1.3°C (95% CI 0.9–1.7, p < 0.001) lower, with lower levels of carbon dioxide (CO2) (mean difference = 97 ppm, 77.8–116.2, p < 0.001) than in poorly ventilated barracks.在通风良好的小屋中,室内温度低1.3 °C(95% CI 0.9–1.7,p < 0.001),二氧化碳(CO2) 水平(平均差= 97 ppm,77.8–116.2,p < 0.001)低于在通风不良的小屋里。在 通风 良好 的 小屋 中 室内 温度 低 低 1.3 ° C (95% Ci 0.9–1.7 , p <0.001) 二氧化 碳 碳 碳 水平 平均 差 差 = 97 ppm , 77.8–116.2 , p <0.001) 通风 通风 通风 通风 通风 通风 通风 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 HIP不良的小屋里。 В хорошо проветриваемом салоне температура в помещении была на 1,3 °C ниже (95% ДИ 0,9–1,7, p < 0,001), а уровень углекислого газа (CO2) (средняя разница = 97 частей на миллион, 77,8–116,2, p < 0,001) был ниже. In a well-ventilated cabin, room temperature was 1.3°C lower (95% CI 0.9–1.7, p < 0.001) and carbon dioxide (CO2) levels (mean difference = 97 ppm, 77, 8–116.2, p < 0.001) was lower. lower than in a ventilated cab Poor cab.
While light visible from the outside of the hut increases the penetration of the mesh, good natural ventilation reduces the concentration of indoor carbon dioxide, which is the main bait for mosquitoes, thus reducing the penetration of the mesh.
In sub-Saharan Africa, the majority of malaria transmission occurs at night indoors [1, 2]. The design of the house [3, 4], its height above the ground [5] and the degree of crowding in the building [6] all influence the entry of malarial mosquitoes into the house. One reason for this is that the relative attractiveness of a building depends on how the building emits CO2 produced by the occupants [3]. This gas is the main attractant of mosquitoes [7], and a large concentrated plume is more attractive than a low concentration gas that spreads from many parts of the building [3]. Ultimately, it will be possible to design “invisible” houses that only a few mosquitoes find and enter.
Improved ventilation is needed to reduce the transmission of malaria in homes for a number of reasons: (i) it will reduce indoor carbon dioxide concentrations and reduce the odor plumes emitted by buildings [4], thereby reducing the chance of transmission of blood-seeking mosquitoes. Find someone to feed and spread malaria, (ii) this will keep the bedroom cool by cooling the body and reducing the carbon dioxide produced by people sleeping in the room[4], and (iii) cooling the home makes it more likely that people will sleep under mosquito nets [8]. Based on the need to ventilate and cool the house well, scientists have developed several prototype houses to reduce the entry of mosquitoes [9]. The walls of the house are made of light and shade fabric, which allows air and light to pass through, has a low heat capacity, which leads to a rapid cooling of the house at night. A pilot study of six prototype well-ventilated houses in Tanzania showed a 95% reduction in mosquito penetration into a two-story building and a shielded one-story stilt building compared to an unmodified reference house by 70%. Raised one-story and two-story buildings were 2.3°C colder (95% CI 2.2–2.4) than conventional dwellings. Therefore, the use of wall construction materials with increased ventilation and low thermal mass results in fewer indoor mosquitoes and lower indoor temperatures. In addition, raising houses can also reduce mosquito entry, as shown in an experimental study of huts in the Gambia, in which individual huts were raised or lowered to different heights [5].
Based on these encouraging results, a randomized controlled trial (RCT) is being conducted in a rural area of ​​southeastern Tanzania to investigate the health effects of a new healthy home called Star House (Figure 1A) [9]. Star Residence is a two-story building with bedrooms on the top floor and a kitchen and storage room on the ground floor. The house is designed to be cool and airy, mainly because it is built with shading panels and most of the walls are breathable. However, before testing began, the new home and study design had two problems that led to the series of experiments described here. First, it was assumed that the light from the light traps that the Centers for Disease Control and Prevention (CDC) used to assess the protective effectiveness of these homes could be seen from the outside of the homes and likely attract more mosquitoes to the homes than at night. No traps were used—the mosquito repellant was inflated at Star’s house. Second, given that open eaves are the main entry route for Anopheles gambiae (sl) into ordinary houses, there are small gaps under the corrugated roof slabs of Star houses that can be important entry points for mosquitoes (Figure 1B). 10, 11]. The experiments described here aim to answer these questions, while at the same time evaluating how the light emitted by the light trap, combined with improved ventilation, affects the behavior of Anopheles arabinis, the most common vector of malaria in the Rift Valley and Rift Valley. Valley. Sahara More arid regions of southern Africa [12].
star house. Exterior view; B Interior view: bright light above breathable mesh walls and green-tinted purlins and under a corrugated iron roof with roof openings
The study was conducted in Mosquito City, a part-field system of the Ifakara Health Institute, near the village of Kiningina (8.11417 S, 36.67484 E), approximately 5 km north of Ifakara city, Tanzania, during drought. season, 72 nights (i.e., 3 experiments from September 2020 to February 2021 [13, 14] × 24 nights) (Fig. 2). Briefly, the semi-floor system is a large outdoor cage consisting of a metal frame-shell and mesh walls resting on a concrete floor 4.53 m high and 553 m2 in area (Fig. 2) [15]. The building consists of six identical rooms, each with a floor area of ​​9.6m × 9.6m and a side wall height of 4.1m, each with an experimental cabin. In each room, the floor was covered with local soil to a depth of 400 mm, which allowed vegetation to grow inside [14, 16]. Four rooms are used every night: two with a cabin and two with a comparison cabin.
The Ifakara Health Institute is located in the semi-field section of the Mosquito City complex in the village of Kiningina with experimental cabins in individual cages.
Treatment was administered to four-day, four-room cohorts using a randomized block design. This is a balanced design, so every possible combination of cabin types was tested after six blocks, with each cabin type tested in three blocks in each room (Supplementary File 1: Table S1). At the start of each experiment, the sleeper was randomly assigned to a cabin and then rotated between cabins over the next three nights, so that at the end of the four-day block, everyone in each cabin slept six times. This design quantifies the effect of cabin type, adjusting for night-to-night transition, bed, and room. For each experiment, mosquitoes were collected indoors using light traps every Thursday evening for six weeks (n = 24 nights).
Three experiments were carried out using four experimental cabins, each with an adult male. Each research group had two booths, each inside a large shielded cage (Figure 2). 300 amps per night. Arabidopsis females were released into each cage outside the hut and collected indoors using a CDC light trap. Experiment 1 compared booths with light-transmitting walls and booths with opaque walls, and its purpose was to determine whether more mosquitoes entered booths with light-transmitting walls compared to booths with opaque walls. In Experiment 2, openings under the corrugated roof of a hut with shaded walls were compared with a star-shaped dwelling with a similar hut without openings under the roof. This is done to determine if small openings in the roof increase mosquito entry. In Experiment 3, star dwelling-style cottages were compared with traditional adobe-walled, thatched-roofed houses, replicating the types of houses found in the RCT study area. The results of the experiments are shown in Figure 3.
Summary of the experiment. The reference cabin in each experiment is shown in the first column of each row. Locally unusable doors were simulated in each experiment by adding narrow gaps above and below each door.
Details of the experimental cabin are shown in Figure 3 and attached file 1. In Experiment 1, a cabin with light-transmitting walls was compared with a cabin with opaque walls. It is important to note that the walls consist of two layers: an outer layer of dense fabric and an inner layer of transparent or opaque plastic. The design compares only the light effect, keeping the same internal temperature for both cabin types. Each hut is built using a 25.4mm2 iron metal frame, with a floor area of ​​2.62m x 1.86m, with a wall height of 2.0m and a 150mm high eaves under an overhanging roof. Each hut has a metal door 1.75 m high and 75 cm wide with slots 20 mm high and 750 mm wide above and below the door, imitating the awkward doors common in the village. The roof is made of corrugated board and has an inclined design.
In experiment 1, a light-transmitting wall was constructed from panels composed of 80% light-blocking green mesh (UV stabilized high-density polyethylene mesh, Multiknit Ltd, South Africa) with a mesh size of 2 mm × 2 mm on the outer surface, black opaque high 2.4m x 0.69m x 0.8mm thick PE inner face (JK Platopack Pvt Ltd, Ahmedabad, India) or similar but the same size as clear transparent plastic film (bronze, JK Platopack Pvt Ltd, Ahmedabad, India) Medabad; figure 3). Use Velcro straps to hold interior panels in place so panels can be easily moved between cabins.
In Experiment 2, the construction of the Star family hut was similar to that described in Experiment 1, although in this experiment there were no plastic film interior panels, and the gaps in the eaves were either open or closed. The experiment compared cabins with small gaps (24 mm wide and 18 mm radius) formed under corrugated roof slabs formed on purlins (horizontal beams along the length of the roof supporting the rafters), these openings in the roof for houses with sponge (Fig. 3) .
In Experiment 3, the Star family hut described in Experiment 2 was compared with traditional style huts commonly found in Tanzania and other parts of Sub-Saharan Africa (Figure 3). The traditional hut has a floor area of ​​3.1 m × 2.7 m and a wall height of 1.8 m. sides. In front of the hut there is a door 1.75 m high and 0.75 m wide. The cabin has four windows measuring 0.56 m x 0.56 m, one on each side of the cabin. Although the windows were closed during the experiments, they had a 5 mm wide gap on the vertical side of each window to simulate an unsuitable window.
Sleepers were enrolled in the study after signing a consent form and tested for the presence of malaria parasites using a rapid test (paraHIT®f, Span Diagnostics Ltd, Sachin (Surat), India). All tests are negative. During the study period, these people did not smoke, drink alcohol, or wear perfume.
Three hundred hungry 5-8 day old female An. Every night at 18:30, Arabiensis is released into each room 3 m from the front door of each cottage. A man between the ages of 18 and 35 slept in each hut under a full insecticide-treated net (Olyset chain, Sumitomo Chemical, Arusha, Tanzania), 0.9 m wide, 1.8 m long and 1.8 m high. Sleepers enter to the cabin at 19:00 and leave at 07:00 the next day. Mosquitoes were collected in each hut using a CDC light trap (incandescent lamp type 512, BioQuip Products, CA, USA) with a lamp 1 m above the floor at the foot of the bed, operating from 19:00 to 07:00. Mosquitoes in light traps were collected and killed by exposure to chloroform. Every morning, use a mechanical aspirator (Prokopack® Model 1419, John W. Hock Co., Gainesville, USA) to remove any remaining mosquitoes inside and outside the cottage. The mosquitoes collected by the light trap and aspirator were counted (Additional file 1).
After turning off the light traps at 07:00, stationary mosquitoes were also collected. Every morning between 07:15 and 07:45, use a mechanical aspirator (Prokopack® Model 1419, John W. Hock Co., Gainesville, USA) to remove any remaining mosquitoes inside and outside the hut. Start collecting stationary mosquitoes in a hut, then on the street. Gather more mosquitoes to make sure there are no mosquitoes left in the hut and room that could interfere with the next day’s experiments. Count and record resting mosquitoes collected indoors and outdoors using a mechanical aspirator.
Room temperature, carbon dioxide concentration, and relative humidity were recorded using a data logger (CO2Meter.com, model CM-0018-AA, GasLab, Florida, USA). Data loggers are located in the center of each cabin 1 m above the ground and record at 30-minute intervals from 18:30 to 07:00. Outdoor air temperature, carbon dioxide concentration and relative humidity were measured only in experiment 3 at a height of 1 m from the center of each large cage, 5 m from each hut.
The primary result was the proportion of finding a host and rest. arabiensis were collected from each cabin every night using a light trap and a Prokopack aspirator. Secondary outcomes were mean indoor temperature and mean indoor carbon dioxide concentration recorded from 19:00 to 07:00.
The sample size was estimated based on a previously completed study [17] in the study area, where An. arabic was collected 10.4 (SD = 21.5) per trap per night. Sample size modeling was based on a negative binomial distribution with a 5% significance level and 90% power to detect a 50% reduction in house mosquitoes, a 24-day (six-week) experiment was sufficient.
Data analysis was carried out using R (version 3.3.2) [18], using the lme4 [19, 20] and dplyr [21] packages. Mosquito count data were modeled using a generalized linear mixed effects model (glmer) using a binomial distribution to account for the logarithmic relationship function. The number of mosquitoes recaptured on an SFS camera on a given night is expressed as the proportion of mosquitoes released into that camera. The response variable was the proportion of mosquitoes caught in the light traps, and cabin type was included as a fixed factor. Sleep, room id and night are included as fixed effects. The model coefficients are raised to a power to obtain the odds ratio (OR) and 95% confidence intervals. Adjusted mean night temperature difference, relative humidity and carbon dioxide concentrations, and their night/hut values ​​(95% CI) were calculated using a linear mixed effects model (lmer) modeled with a normal distribution. Analysis of variance was used to estimate significance levels (p-values) of mean differences in environmental conditions derived from the salon/night typology. Experiment 3 used a paired t-test to compare the average indoor carbon dioxide concentration with the average outdoor carbon dioxide concentration for each cabin type.
During the experiment, 69.5% (10,010/14,400) mosquitoes were collected in booths with transparent walls compared to 53.8% (7,747/14,400) in booths with opaque walls. The mean percentage of mosquitoes collected in each hut was 69.9% (95% CI, CI 67.4–72.3) and 55.8% (95% CI 52.9–58.6) in huts with transparent walls in huts with opaque walls. The adjusted analysis showed that the odds of finding mosquitoes in huts with transparent walls, where the light could be seen from outside, was 84% greater than huts with opaque walls, where little, if any light, was visible from outside (Odds ratio, OR = 1.84, 95% CIs 1.74–1.95, p < 0.001, Table 1). The adjusted analysis showed that the odds of finding mosquitoes in huts with transparent walls, where the light could be seen from outside, was 84% ​​greater than huts with opaque walls, where little, if any light, was visible from outside (Odds ratio, OR = 1.84, 95% CIs 1.74–1.95, p < 0.001, Table 1). Adjusted analysis showed that huts with transparent walls, where light was visible from the outside, were 84% more likely to detect mosquitoes than huts with opaque walls, where little, if any, light was visible from outside (Chances). соотношение, ОШ = 1,84, 95% ДИ 1,74–1,95, р < 0,001, табл. ratio, OR = 1.84, 95% CI 1.74–1.95, p < 0.001, tab. one).调整后的分析表明,在可以从外面看到光线的透明墙壁小屋中发现蚊子的几率比不透明墙壁的小屋高出84%,在不透明墙壁的小屋中,从外面几乎看不到任何光线(优势比, OR = 1.84, 95% CIs 1.74–1.95, p < 0.001, 表1)。调整后的分析表明,在可以从外面看到光线的透明墙壁小屋中发现蚊子的几率比不透明墙壁的小屋高出84%,在不透明墙壁的小屋中,从外面几乎看不到任何光线(优势比, OR = 1.84, 95% CIs 1.74–1.95, p < 0.001, 表1)。 The adjusted analysis showed that mosquitoes were 84% more likely to be found in cabins with transparent walls, where the light was visible from the outside, than in cabins with opaque walls, where the light from the outside was almost invisible (odds ratio). 1,84, 95% ДИ 1,74–1,95, p < 0,001, табл. 1.84, 95% CI 1.74–1.95, p < 0.001, tab. one). There were no differences in average nighttime room temperature or indoor CO2 levels between the two cabins (Table 3), suggesting that the difference in mosquito penetration was due to light only and not to temperature or CO2.
There is no difference in the safety of indoor recreation. arabiensis were collected in different types of houses (odds ratio = 0.89, 95% CI 0.74–1.05, p = 0.17). Outdoor recreation is less protected. arabiensis in transparent-walled houses compared to opaque-walled houses (OR = 0.57, 95% CIs 0.54–0.64, p < 0.001; Table 2). arabiensis in transparent-walled houses compared to opaque-walled houses (OR = 0.57, 95% CIs 0.54–0.64, p < 0.001; Table 2). arabiensis в птичниках с прозрачными стенами по сравнению с птичниками с непрозрачными стенами (ОШ = 0,57, 95% ДИ 0,54–0,64, р < 0,001; таблица 2). arabiensis in transparent-walled houses compared to non-transparent-walled houses (OR = 0.57, 95% CI 0.54–0.64, p < 0.001; Table 2).与不透明墙壁房屋相比,透明墙壁房屋中的阿拉伯阿拉伯人(OR = 0.57, 95% CIs 0.54–0.64, p < 0.001; 表2)。 (OR = 0.57, 95% CIs 0.54–0.64, p < 0.001; 表2)。 Арабы в домах с прозрачными стенами по сравнению с домами с непрозрачными стенами (ОШ = 0,57, 95% ДИ 0,54–0,64, р <0,001; таблица 2). Arabs in houses with transparent walls compared with houses with opaque walls (OR = 0.57, 95% CI 0.54–0.64, p < 0.001; Table 2).
In this experiment, only 1.0% (144/14,400) of mosquitoes were collected in houses with open roof slots compared to 0.6% (80/14,400) in houses with slots. The average percentage of mosquitoes collected in each hut was 0.03% (95% CI 0.01–0.12) and 0.02% (95% CI 0.0–0.1) with no gaps. In the adjusted analysis, 46% fewer mosquitoes were collected in huts with no gaps than those with open gaps (OR = 0.54, 95% CIs 0.41–0.72, p < 0.001) (Table 1). In the adjusted analysis, 46% fewer mosquitoes were collected in huts with no gaps than those with open gaps (OR = 0.54, 95% CIs 0.41–0.72, p < 0.001) (Table 1). В скорректированном анализе в хижинах без щелей было собрано на 46% меньше комаров, чем в хижинах с открытыми щелями (ОШ = 0,54, 95% ДИ 0,41–0,72, р < 0,001) (таблица 1). In an adjusted analysis, 46% fewer mosquitoes were collected in huts without slots than in huts with open slots (OR = 0.54, 95% CI 0.41–0.72, p < 0.001) (Table 1).在调整后的分析中,没有缝隙的小屋中收集的蚊子比有缝隙的小屋少46%(OR = 0.54, 95% CIs 0.41–0.72, p < 0.001)(表1)。在调整后的分析中,没有缝隙的小屋中收集的蚊子比有缝隙的小屋少46%(OR = 0.54, 95% CIs 0.41–0.72), p < 0.72) В скорректированном анализе в хижинах без щелей было собрано на 46% меньше комаров, чем в хижинах с щелями (ОШ = 0,54, 95% ДИ 0,41–0,72, р < 0,001) (табл. 1). In an adjusted analysis, 46% fewer mosquitoes were collected in huts without slots than in huts with slots (OR = 0.54, 95% CI 0.41–0.72, p < 0.001) (Table 1). There were no differences in temperature and carbon dioxide between the two types of cabins (Table 3).
Houses with a closed cornice are less likely to rest indoors. arabiensis than those with open-eaves (OR = 0.19, 95% CIs 0.08–0.46, p < 0.001). arabiensis than those with open-eaves (OR = 0.19, 95% CIs 0.08–0.46, p < 0.001). arabiensis, чем с открытыми карнизами (ОШ = 0,19, 95% ДИ 0,08–0,46, р <0,001). arabiensis than with open cornices (OR = 0.19, 95% CI 0.08–0.46, p<0.001). arabiensis 比那些开檐的(OR = 0.19, 95% CIs 0.08–0.46, p < 0.001)。 arabiensis 比那些开檐的(OR = 0.19, 95% CIs 0.08–0.46, p < 0.001)。 arabiensis, чем с открытым карнизом (ОШ = 0,19, 95% ДИ 0,08–0,46, р <0,001). arabiensis than with open eaves (OR = 0.19, 95% CI 0.08–0.46, p<0.001). There was a corresponding increase in outdoor-resting mosquitoes in cages with huts with closed eaves compared to cages with open eave huts (OR = 1.03, 95% CIs 0.97–1.09, p < 0.05; Table 2). There was a corresponding increase in outdoor-resting mosquitoes in cages with huts with closed eaves compared to cages with open eave huts (OR = 1.03, 95% CIs 0.97–1.09, p < 0.05; Table 2). Соответствующее увеличение числа комаров, отдыхающих на открытом воздухе, наблюдалось в клетках с хижинами с закрытыми навесами по сравнению с клетками с хижинами с открытыми навесами (ОШ = 1,03, 95% ДИ 0,97–1,09, р < 0,05; таблица 2). A corresponding increase in the number of mosquitoes resting outdoors was observed in cages with closed huts compared to cages with open huts (OR = 1.03, 95% CI 0.97–1.09, p < 0.05 ; table 2).与开檐小屋的笼子相比,带封闭檐小屋的笼子中户外休息的蚊子相应增加(OR = 1.03,95% CIs 0.97-1.09,p < 0.05;表2)。与 开檐 小屋 的 笼子 相比 带 封闭 檐 小屋 笼子 中 户外 休息 的 蚊子 相应 增加 ((or = 1.03,95% cis 0.97-1.09 , p <0.05 ; 2)。。。。。。。。。))))))))))))))))))))))) Было соответствующее увеличение количества комаров, отдыхающих на открытом воздухе в клетках с закрытыми хижинами по сравнению с клетками в хижинах с открытыми крышами (ОШ = 1,03, 95% ДИ 0,97–1,09, р < 0,05; таблица 2). There was a corresponding increase in the number of mosquitoes resting outdoors in cages with closed huts compared to cages in huts with open roofs (OR = 1.03, 95% CI 0.97–1.09, p < 0.05; Table 2 ).
In this experiment, only 0.3% (46/14,400) of mosquitoes were collected in the Star family’s well-ventilated home, compared to 29.5% (4246/14,400) in the traditional-style poorly ventilated home. The average percentage of mosquitoes collected in each hut was 0.3% (95% CI 0.16–0.66) in star huts and 19.3% (95% CI 17.0–21.9) in traditional huts. type. The adjusted analysis showed that the odds of mosquito house entry was 99% less in well-ventilated huts than poorly-ventilated huts (OR = 0.01, 95% CIs 0.01–0.03, p < 0.001, Table 1). The adjusted analysis showed that the odds of mosquito house entry was 99% less in well-ventilated huts than poorly-ventilated huts (OR = 0.01, 95% CIs 0.01–0.03, p < 0.001, Table 1). Скорректированный анализ показал, что вероятность проникновения комаров в дом была на 99% меньше в хорошо проветриваемых хижинах, чем в плохо вентилируемых хижинах (OR = 0,01, 95% CI 0,01–0,03, p <0,001, таблица 1). Adjusted analysis showed that the likelihood of mosquito entry into the home was 99% less in well-ventilated huts than in poorly ventilated huts (OR = 0.01, 95% CI 0.01–0.03, p < 0.001, Table 1) .调整后的分析表明,在通风良好的小屋中,蚊子进入的几率比通风不良的小屋低99%(OR = 0.01, 95% CIs 0.01-0.03, p < 0.001,表1)。调整 后 的 分析 表明 , 在 良好 的 小屋 中 蚊子 进入 的 几率 比 通风不良 的 小 屋 低 低 低 99% ((((((((((((((, 95% CIS 0.01-0.03, p <0.001 , 表 1)。。。。。。。。。。))))))))))))))))))))))))))) Скорректированный анализ показал, что вероятность проникновения комаров в хорошо проветриваемые хижины была на 99% ниже, чем в плохо проветриваемых хижинах (ОШ = 0,01, 95% ДИ 0,01–0,03, р < 0,001, таблица 1). Adjusted analyzes showed that well-ventilated huts were 99% less likely to enter mosquitoes than poorly ventilated huts (OR = 0.01, 95% CI 0.01–0.03, p < 0.001, Table 1).
The odds of collecting indoor-resting mosquitoes was 88% less in well-ventilated, Star-home-style huts than traditional-style huts (OR = 0.12, 95% CIs 0.06–0.23, p < 0.001). The odds of collecting-resting mosquitoes was 88% less in well-ventilated, Star-home-style huts than traditional-style huts (OR = 0.12, 95% CIs 0.06–0.23, p < 0.001). Вероятность сбора отдыхающих в помещении комаров была на 88% меньше в хорошо проветриваемых хижинах типа «звездный дом», чем в традиционных хижинах (ОШ = 0,12, 95% ДИ 0,06–0,23, р <0,001). The likelihood of collecting indoor mosquitoes was 88% less in well-ventilated star house huts than in traditional huts (OR = 0.12, 95% CI 0.06–0.23, p < 0.001).与传统风格的小屋相比,在通风良好的星屋式小屋中,收集室内静息蚊子的几率要低88%(OR = 0.12, 95% CIs 0.06–0.23, p < 0.001)。与 传统 风格 的 小屋 相比 , 通风 良好 的 星屋式 中 , 收集 室内 静息 蚊子 的 要 低 低 低 88% (OR = 0.12, 95% CIS 0.06–0.23, p <0.001。。。。。。。。。。。。。。。。。。。。。。。))))) Вероятность сбора отдыхающих комаров в помещении была на 88% ниже в хорошо проветриваемых домиках типа «звездный дом», чем в домиках традиционного типа (ОШ = 0,12, 95% ДИ 0,06–0,23, р <0,001). The likelihood of collecting resting mosquitoes indoors was 88% lower in well-ventilated star-houses than in traditional houses (OR = 0.12, 95% CI 0.06–0.23, p < 0.001). As a result, the chance to collect outdoor recreation in the Star House cage increases. arabiensis than traditional-style huts (OR = 3.04, 95% CIs 2.90–3.20, p < 0.001; Table 2). arabiensis than traditional-style huts (OR = 3.04, 95% CIs 2.90–3.20, p < 0.001; Table 2). arabiensis, чем хижины традиционного типа (ОШ = 3,04, 95% ДИ 2,90–3,20, р <0,001; таблица 2). arabiensis than traditional huts (OR = 3.04, 95% CI 2.90–3.20, p < 0.001; Table 2). arabiensis 比传统风格的小屋(OR = 3.04, 95% CIs 2.90–3.20, p < 0.001; 表2)。 arabiensis 比传统风格的小屋(OR = 3.04, 95% CIs 2.90–3.20, p < 0.001; 表2)。 arabiensis, чем хижины традиционного типа (ОШ = 3,04, 95% ДИ 2,90–3,20, р <0,001; таблица 2). arabiensis than traditional huts (OR = 3.04, 95% CI 2.90–3.20, p < 0.001; Table 2).
The indoor temperature was 1.3 °C, (95% CIs 0.9–1.7, p < 0.001) cooler in the Star home-style huts (24.8 °C, 95% CIs 24.6–25.1) than traditional-style huts (26.1 °C, 95% CIs 25.7–26.4). The indoor temperature was 1.3 °C, (95% CIs 0.9–1.7, p < 0.001) cooler in the Star home-style huts (24.8 °C, 95% CIs 24.6–25.1) than traditional-style huts (26.1 °C, 95% CIs 25.7–26.4). Температура в помещении была на 1,3 °C (95% ДИ 0,9–1,7, p < 0,001) ниже в хижинах по-домашнему «Звезда» (24,8 °C, 95% ДИ 24,6–25,1), чем в традиционных хижинах (26,1 °C, 95% ДИ 25,7–26,4). Indoor temperature was 1.3°C (95% CI 0.9–1.7, p < 0.001) lower in Zvezda home-style huts (24.8°C, 95% CI 24.6–25 .1) than traditional huts (26.1°C, 95% CI 25.7–26.4).室内温度为1.3 °C,(95% CIs 0.9–1.7, p < 0.001) 与传统风格的小屋(26.1 °C, 95% CI 25.7–26.4)。室内温度为1.3 °C,(95% CIs 0.9–1.7, p < 0.001) Температура в помещении составляла 1,3 °C (95% ДИ 0,9–1,7, p <0,001) по сравнению с каютами традиционного стиля (26,1 °C, 95% ДИ 25,7–26,4). Room temperature was 1.3°C (95% CI 0.9–1.7, p < 0.001) compared to conventional style cabins (26.1°C, 95% CI 25.7–26.4). There were also lower concentrations of carbon dioxide indoors in Star home-style huts (mean concentration = 320 ppm, 95%, CI 314–327) than traditional-style huts (541 ppm, 95% CI 516.4–565.4, p < 0.001). There were also lower concentrations of carbon dioxide indoors in Star home-style huts (mean concentration = 320 ppm, 95%, CI 314–327) than traditional-style huts (541 ppm, 95% CI 516.4–565.4, p < 0.001) . Также были более низкие концентрации углекислого газа внутри помещений в хижинах «Стар» (средняя концентрация = 320 частей на миллион, 95%, ДИ 314–327), чем в хижинах традиционного стиля (541 частей на миллион, 95% ДИ 516,4–565,4, р <0,001). There were also lower indoor carbon dioxide concentrations in Star huts (mean concentration = 320 ppm, 95%, CI 314–327) than in traditional style huts (541 ppm, 95% CI 516.4– 565.4, p<0.001). . Star 家庭式小屋的室内二氧化碳浓度(平均浓度= 320 ppm,95%,CI 314–327)也低于传统式小屋(541 ppm,95% CI 516.4–565.4,p < 0.001) . Star 家庭式 小屋 的 室内 碳 浓度 平均 浓度 浓度 = 320 ppm , 95% , ci 314–327) 低于 传统式 小 ((((((541 ppm , 95% Ci 516.4–565.4 , p <0.001). Концентрация CO2 внутри кабины семейства Star (средняя концентрация = 320 частей на миллион, 95% ДИ 314–327) также была ниже, чем в обычной кабине (541 частей на миллион, 95% ДИ 516,4–565,4, p < 0,001). The CO2 concentration inside the Star family cabin (mean concentration = 320 ppm, 95% CI 314–327) was also lower than in the conventional cabin (541 ppm, 95% CI 516.4–565.4, p < 0.001 ). Importantly, the CO2 concentration in the Star family cabin was similar to outdoor levels (mean difference = 11 ppm, 95% CI 4-13, p = 0.95), but the CO2 concentration in the traditional style cabin was 232 parts per million per million higher than outdoors (95% CI 176–298, p = 0.03 (Table 3). :00) was 25.1°C (95% CI 24.3–27) and carbon dioxide was 309 ppm (95% CI 290–320).
This series of experiments evaluates three aspects of a stellar home: (1) transparent and opaque walls, (2) the presence and absence of small corrugated iron roof eaves, and (3) permeable walls achieved by darkening the cabin. ventilation. These experiments provide new insights into the effects of light and ventilation on the entry of An into homes, one of the most important vectors of malaria in sub-Saharan Africa. Arab. In this experimental setting, when the light from the CDC light traps was visible from outside the cab, the chances of catching mosquitoes indoors increased by 84% compared to when the light was not visible from outside. It is clear that in this experiment, the light and smells of a person attracted mosquitoes from outside the inhabited hut. In the 1960s, in a pioneering study that pioneered the use of optical traps to collect African mosquitoes, Odetoynbo showed that light was an important element in CDC optical traps because, in the absence of light, the traps collected 95% less An. Gambia sl [22]. Similarly, when Costantini and colleagues used a light trap in a dark room, they collected 63% less An. Gambia sl than light bulb traps [23].
This conclusion is important for several reasons. First, light traps have been the standard tool for indoor mosquito collection in randomized trials of vector control interventions [24, 25]. While this may not be a problem in most studies where the sampling units are normal houses with opaque walls and doors, they can be biased towards samples that use shielded doors or if they are used for houses with many small openings (e.g. bamboo at home) that transmit light. so that it can be seen from outside the house. In a recent trial in the Gambia where mesh doors were installed in village houses, the number of mosquitoes collected indoors was higher than in the control group with solid doors [26]. A study in the Gambia seems to overestimate the density of mosquitoes in houses with mesh doors because the light from the traps is visible from the outside. Secondly, it also raises concerns about whether light traps should be used in tests of mosquito penetration into star houses compared to conventional houses. Third, these results raise the question: Does home lighting increase malaria transmission? The results are mixed: most studies show an increase in malarial mosquito bites associated with electrification [27, 28, 29], possibly due to people spending more time outdoors at night and being bitten by malarial mosquitoes. However, in a study in Tanzania, houses with electricity had fewer mosquitoes than houses without electricity [30]. Because electricity is associated with greater wealth, fewer mosquitoes may be due to higher quality homes having fewer mosquito entry points or mosquito coils than poorer households [30, 31]. It is clear that further research is needed to find out whether electric lamps, including tungsten and LED lamps, are attractive to mosquitoes and at what light intensity.
The response of a mosquito to light is complex because it varies depending on the time of day, the feeding status of the mosquito, and the intensity and wavelength of the light. At dawn and dusk in natural conditions, a significant part of the rest indoors. Gambiae sl, including those semi-pregnant, pregnant, and blood-feeding, are attracted to weak light from windows, and the bright light they receive during the day prevents them from leaving [32, 33]. Host-seeking mosquitoes are also stimulated to fly at dusk due to low light intensity, a behavior controlled by circadian rhythms [34]. Interestingly, when mosquitoes were exposed to bright white light for 10 minutes early in the night, feeding could be interrupted for up to 4 hours [35]. In Brazil, An has decreased tenfold. gambiae sl (now known as An. arabiensis) in light houses compared to the darkest houses [36]. In Canada, nocturnal blood-sucking mosquitoes are attracted to low-intensity colors such as black, blue, and red rather than bright colors such as white and yellow [37], suggesting that this behavior may be related to color choice. dark daytime site. In the Gambia, mosquito hosts are also attracted to large solid objects at a distance of 15–20 m [38]. Gillis and Wilks argue that the profile of a house, or the degree to which it is isolated from other houses or high vegetation, can affect the attractiveness of one house over another. Collectively, there is evidence that while light in the presence of human scents is attractive to host-seeking mosquitoes, the shape and location of dwellings may also be important.
Small gaps were created where the corrugated metal roof rested on the purlins and, as shown in Experiment 2, more mosquitoes entered the hut than a hut without gaps. This is to be expected, as open cornices, the gaps between the tops of the walls and the roof, are Anne’s main route. gambiae sl penetrates the house [10, 11, 39]. However, in this experiment, only a few mosquitoes entered the hut, suggesting that the holes cannot lead to a significant increase in the mosquito population in houses of similar design, such as the Star House. The most plausible explanation for this finding is that, unlike the solid plastic walls used in Experiment 1, the cloth-walled hut attracted fewer mosquitoes because it allowed the carbon dioxide to quickly dissipate from the hut.
In Experiment 3, the Star family’s well-ventilated hut had 99% fewer mosquitoes than a poorly ventilated house-like hut. The main explanation for this difference in attractiveness has to do with the carbon dioxide concentration gradient between the two types of cabins. In the well-ventilated cabin, the concentration of carbon dioxide was only 11 ppm above the outside air level, indicating that the gas was effectively removed from the cabin through the permeable walls. Because mosquitoes can only detect differences in carbon dioxide concentrations above 40 ppm [40], this suggests that they cannot easily detect people sleeping in star-house type cabins. In contrast, the poorly ventilated cabin had much higher concentrations of carbon dioxide, 232 ppm above background levels, which provided a sharp gradient in gas concentration that allowed outdoor mosquitoes to find indoor hosts. These results are supported by a recent study in the Gambia that found that well-ventilated homes can reduce indoor mosquito density by 80% compared to poorly ventilated homes [4]. Well-ventilated huts also reduced interior temperatures by 1.3°C compared to poorly ventilated huts, which can increase human comfort and thus increase the use of mosquito nets [9]. A star house with well-ventilated walls is more likely to act as a “stealth house”, especially if the bedroom is on the second floor. Recent studies have shown that the amount is safe. Gambia sl penetration into residential buildings decreased with height, with mosquito numbers decreasing by 84% when the house was 3 m above the ground [5].
This training has several limitations. First, the experimental huts are smaller than the village houses, so it is unlikely that these results can be directly compared with the field ones. Secondly, only one person sleeps in each hut, while in the village from two to six people sleep in one house [41]. Thirdly, the study was carried out in a semi-field system of laboratory-grown An. arabiensis, they may behave differently than wild mosquitoes because colonization may reduce changes in behavioral traits in wild populations. Fourthly, there was no change in the time when the sleepers went to bed, and they were not allowed to open and close the doors of the hut at will, which prevented access to the mosquito net. Fifth, this study is based on the use of CDC light traps to collect indoor mosquitoes, and the results could be different if sampling methods were used that did not use light as an attractant (eg, trapping landing humans).
The light from the CDC light trap, visible from the outside of the hut, increased the number of host-seeking mosquitoes entering the building compared to huts with opaque walls. While small gaps under the corrugated roof increase access to the inside, in cabins with breathable walls, this results in fewer mosquitoes entering the cabin. In fact, the well-ventilated cottages had significantly fewer mosquitoes than the hotter, more poorly ventilated traditional home. While light traps and holes under the roof increase the number of mosquitoes entering the building, the presence of breathable walls that increase ventilation results in significantly fewer mosquitoes entering the building compared to conventional buildings. Evidence suggests that increased ventilation in buildings will significantly reduce mosquito entry into Tanzania, and is supported by studies in the Gambia [4] suggesting that this could be widely applied to malaria control in the region. Given that no other simple sampling instruments exist that are immune to operator bias, this also suggests that routine sampling using optical traps can be done at Star’s home, although this may slightly overestimate the true mosquito entry rate. As far as healthy home design is concerned, filling small roof openings may have little effect on the total number of mosquitoes entering such homes. Most importantly, the results complement the literature showing that increasing home ventilation in sub-Saharan Africa can help reduce malaria transmission and keep bedrooms cool at night.
[PubMed] Kaindoa E.V., Matovo N.S., Ngowo H.S., Mkandavile G., Mmbando A., Finda M., Okumu F.O. Effective interventions targeting the Anopheles mosquito could greatly improve the control of ongoing malaria transmission in southeastern Tanzania. PLOS One. 2017;12:e0177807.
Sherrard-Smith E, Skarp JE, Beale AD, Fornadel C, Norris LC, Moore SJ, etc. Mosquito feeding behavior and how it affects residual malaria transmission in Africa. Proc Nat Acad Sci USA. 2019;116:15086-95.
Jatta E, Jawara M, Bradley J, Jeffreys D, Kande B, Knudsen JB et al. How house design affects density, temperature and relative humidity of Anopheles mosquitoes: a pilot study in rural Gambia. Lancet Planet Health. 2018; 2: e498–508.
Giatta E., Carrasco-Tenezaka M., Javara M., Bradley J., Cesay S., D’Alessandro W. and others. Effect of increased ventilation on indoor temperature and density of Anopheles mosquitoes: a pilot study in The Gambia. JR Soc interface. 2021;18:20201030.
Carrasco-Tenezaka M, Javara M, Abdi M.Yu., Bradley J., Britten O.S., Sizey S. et al. Relationship between house height and mosquito entry into houses: a pilot study in rural Gambia. JR Soc interface. 2021;18:20210256.
Kaindoa E.V., Mkandavile G., Ligamba G., Kelly-Hope L.A., Okumu F.O. Correlation between household employment and malaria vector bite risk in rural Tanzania: Implications for high-resolution spatial containment of control measures. Malar J. 2016; 15:199.
Gillis M. The role of carbon dioxide in mosquito hosts (Diptera: Culicidae): a review. Tank with bovine insects. 1980; 70:525–32.
Pulford J, Hetzel MV, Bryant M, Siba PM, Muller I. Reasons for not using mosquito nets when reporting: a review of the published literature. Malar J. 2011; 10:83.
von Seidlein L, Ikonomidis K, Mshamu S, Nkya TE, Mukaka M, Pell C, et al. Affordable Housing Project to Improve the Health of Rural People in Africa: A Field Study in North East Tanzania. Lancet Planet Health. 2017;1:e188-99.
Nzhi M., Dilger E., Lindsey S.W., Kirby M.J. Significance of eaves for entry into the house of mosquitoes of the genus Anopheles, but not mosquitoes-culicines. J Med Entomol. 2014;46:505–10.
Lindsey S, Snow R. Rooftop Trouble, Invasion of Homes by Malaria Vectors. Trans R Soc Trop Med Hyg., 1988;82:645-6.
Wiebe A, Longbottom J, Gleave K, Shearer FM, Sinka ME, Massey NC, etc. Geographic distribution and evidence for insecticide resistance of African related malaria vectors. Malar J. 2017; 16:85.


Post time: Sep-13-2022
WhatsApp Online Chat !