Spatiotemporal distribution and bionomics of Anopheles stephensi in different eco-epidemiological settings in Ethiopia

Background: Malaria is a major public health concern in Ethiopia, and its incidence could worsen with the spread of the invasive mosquito species Anopheles stephensi in the country. This study aimed to provide updates on the distribution of An. stephensi and likely household exposure in Ethiopia. Methods: Entomological surveillance was performed in 26 urban settings in Ethiopia from 2021 to 2023. A kilometer-by-kilometer quadrant was established per town, and approximately 20 structures per quadrant were surveyed every 3 months. Additional extensive sampling was conducted in 50 randomly selected structures in four urban centers in 2022 and 2023 to assess households’ exposure to An. stephensi. Prokopack aspirators and CDC light traps were used to collect adult mosquitoes, and standard dippers were used to collect immature stages. The collected mosquitoes were identified to species level by morphological keys and molecular methods. PCR assays were used to assess Plasmodium infection and mosquito blood meal source. Results: Catches of adult An. stephensi were generally low (mean: 0.15 per trap), with eight positive sites among the 26 surveyed. This mosquito species was reported for the first time in Assosa, western Ethiopia. Anopheles stephensi was the predominant species in four of the eight positive sites, accounting for 75–100% relative abundance of the adult Anopheles catches. Household-level exposure, defined as the percentage of households with a peridomestic presence of An. stephensi, ranged from 18% in Metehara to 30% in Danan. Anopheles arabiensis was the predominant species in 20 of the 26 sites, accounting for 42.9–100% of the Anopheles catches. Bovine blood index, ovine blood index and human blood index values were 69.2%, 32.3% and 24.6%, respectively, for An. stephensi, and 65.4%, 46.7% and 35.8%, respectively, for An. arabiensis. None of the 197 An. stephensi mosquitoes assayed tested positive for Plasmodium sporozoite, while of the 1434 An. arabiensis mosquitoes assayed, 62 were positive for Plasmodium (10 for P. falciparum and 52 for P. vivax). Conclusions: This study shows that the geographical range of An. stephensi has expanded to western Ethiopia. Strongly zoophagic behavior coupled with low adult catches might explain the absence of Plasmodium infection. The level of household exposure to An. stephensi in this study varied across positive sites. Further research is needed to better understand the bionomics and contribution of An. stephensi to malaria transmission. Graphical Abstract

Risky HIV sexual behavior and utilization of voluntary counseling and HIV testing and associated factors among undergraduate students in Addis Ababa, Ethiopia

Abstract Background HIV/AIDS is a major public health problem in Ethiopia. University students are often a young and sexually active group that is at risk of acquiring and transmitting HIV. We assessed risky HIV sexual behaviors and utilization of voluntary counseling and testing services among undergraduate students at Addis Ababa Science and Technology University, Ethiopia. Methods A cross-sectional study was conducted between May and June, 2013. Standardized semi-structured self-administered questionnaire was used to collect data. Simple random sampling technique was use to select departments from each school. All students in the selected departments were the study participants. Data were entered into EPI-Info and analyzed using SPPS statistical packages. P-value < 0.05 was considered as statistically significant. Results Of the total 602 students selected, an overall response rate of 557 (92.6%) were registered. Among the participants 361 (60%) were males. The student ages’ were ranged from 17 up to 25 years with mean age of 20.3 ± 1.6. Around 385 (64%) of them were in the age group of 17 up to 20 years. Among the study participants, 161 (26.8%) had sexual contact and the mean age of first sexual encounter was 17.4 (SD =2.3) years. About 443 (76%) of students knew that condoms can prevent Sexually Transmitted Infections (STIs). Among sexually active students, 74 (46%) had not used condom during first time sex. Among those responded, 488 (83.4%) had heard information about VCT; however, 52% had not ever used VCT service. The overall mean score of knowledge and attitude of students towards risk perception on HIV was around 66% and 57%, respectively. Students who enrolled in health science departments had almost three time more knowledge [AOR(95%CI) = 2.83 (1.67, 4.80)] and two and half times more favorable [AOR (95% CI) = 2.55 (1.60, 4.06)] attitudes towards HIV risk reduction strategies than students in non-health related departments. Conclusions Some students were engaged in risky sexual behaviour even though they had heard about HIV/AIDS. The perception of risk for acquisition of HIV infection and utilization of VCT were low. HIV prevention and control strategies including education in the areas of HIV/AIDS as part of university programs curriculum, specially non-health students, and strengthening health institutions to provide youth-friendly VCT services for HIV with “know your HIV status” campaigns are strongly recommended

Efficacy of Chloroquine for the Treatment of <i>Vivax malaria</i> in Northwest Ethiopia

<div><p>Background</p><p>Resistance to anti-malarials is a major challenge for effective malaria control in sub-Saharan Africa. This triggered a need for routine monitoring of the efficacy of the antimalarial drugs every two years in all malaria endemic countries. Chloroquine remained the drug of choice for the treatment of vivax malaria in Ethiopia. Though, a strong scientific evidence of chloroquine resistance to <i>P</i>.<i>vivax</i> that could have brought change of treatment regimen is yet to be established in Ethiopia, continuous and regular monitoring of drug’s efficacy is critical for establishing rational anti-malarial drug policies. This study therefore, assessed the therapeutic efficacy of Chloroquine (CQ) for the treatment of <i>Plasmodium vivax</i> infections in Northwestern Ethiopia.</p><p>Methods</p><p>An observational, 28- day therapeutic clinical efficacy study was conducted from August to December, 2014, in Northwest Ethiopia. Patients confirmed to have monoinfection of vivax malaria, aged above 6 months were included. All subjects were treated with standard chloroquine dose of 25 mg/kg for three (3) days. Parasitological and clinical outcomes of treated patients were then evaluated on days 1, 2, 3, 7, 14, 21, and 28 during the entire 28-day follow-up period. A portable spectrophotometer (HemoCue Hb 301 System, Sweden) was used to estimate hemoglobin concentration.</p><p>Results</p><p>A total of 69 subjects had completed follow up. Some 57/69 (82.6%) had fever at enrolment and the rest 12 patients 48 hours before enrollment. Out of total, 65/69 (94.2%) and 66/69 (95.6%) of the study subjects were free of fever by day 1 and day 2 respectively but fever was cleared in all subjects by day 3. At base line the mean asexual parasitemia was 3540 parasites/μL of blood. Parasite carriage on day 3 was 3%. The overall cure rate (an adequate and clinical parasitological response) was very high (97%) [(95% CI = 93.1–99.4)]. The time to parasite, fever and gametocyte clearance as expressed in mean (SD) was 35 (3), 25 (4.6), 28 (3.2) hours respectively. Mean hemoglobin was significantly increased (P<0.001) from 12.2 (7–15) g/dl at day 0 to 13.3 (10–16) g/dl on day 28.</p><p>Conclusions</p><p>In view of our findings, CQ remains efficacious for the treatment of vivax malaria in the study area. However, there is a need to monitor CQR regularly using molecular and or biochemical tools for better evaluation of treatment outcomes.</p></div

Parasite and fever clearance rate and hemoglobin recovery in study participants Bullen Health center, Northwest Ethiopia.

<p>Parasite and fever clearance rate and hemoglobin recovery in study participants Bullen Health center, Northwest Ethiopia.</p

Pattern of parasite, gametocyte and fever clearance in <i>P</i>. <i>vivax</i> monoinfected patients treated with Chloroquine in Northwest Ethiopia.

<p>Pattern of parasite, gametocyte and fever clearance in <i>P</i>. <i>vivax</i> monoinfected patients treated with Chloroquine in Northwest Ethiopia.</p

Hemoglobin concentrations and degree of anemia in <i>P</i>. <i>vivax</i> infected patients before CQ treatment and at the end of treatment follow up, with respect to age, Northwest Ethiopia (August–December, 2015).

<p>Hemoglobin concentrations and degree of anemia in <i>P</i>. <i>vivax</i> infected patients before CQ treatment and at the end of treatment follow up, with respect to age, Northwest Ethiopia (August–December, 2015).</p

Patient recruitment and follow-up for the trial of CQ efficacy against <i>P</i>. <i>vivax</i> malaria in Bullen Health Centre Northwest Ethiopia (17 August to 19 December, 2014).

<p>Patient recruitment and follow-up for the trial of CQ efficacy against <i>P</i>. <i>vivax</i> malaria in Bullen Health Centre Northwest Ethiopia (17 August to 19 December, 2014).</p

Baseline characteristics of the study participants, Bullen Health Center, August-December, 2014, Bullen, Ethiopia.

<p>Baseline characteristics of the study participants, Bullen Health Center, August-December, 2014, Bullen, Ethiopia.</p

Map of the study site.

<p>Metekel Zone, Bullen District.</p