Another dengue fever outbreak in Eastern Ethiopia—An emerging public health threat

Abstract

Background Dengue Fever (DF) is a viral disease primarily transmitted by Aedes (Ae.) aegypti mosquitoes. Outbreaks in Eastern Ethiopia were reported during 2014–2016. In May 2017, we investigated the first suspected DF outbreak from Kabridahar Town, Somali region (Eastern Ethiopia) to describe its magnitude, assess risk factors, and implement control measures. Methods Suspected DF cases were defined as acute febrile illness plus ≥2 symptoms (headache, fever, retro-orbital pain, myalgia, arthralgia, rash, or hemorrhage) in Kabridahar District residents. All reported cases were identified through medical record review and active searches. Severe dengue was defined as DF with severe organ impairment, severe hemorrhage, or severe plasma leakage. We conducted a neighborhood-matched case-control study using a subset of suspected cases and conveniently-selected asymptomatic community controls and interviewed participants to collect demographic and risk factor data. We tested sera by RT-PCR to detect dengue virus (DENV) and identify serotypes. Entomologists conducted mosquito surveys at community households to identify species and estimate larval density using the house index (HI), container index (CI) and Breteau index (BI), with BI≥20 indicating high density. Results We identified 101 total cases from May 12–31, 2017, including five with severe dengue (one death). The attack rate (AR) was 17/10,000. Of 21 tested samples, 15 (72%) were DENV serotype 2 (DENV 2). In the case-control study with 50 cases and 100 controls, a lack of formal education (AOR [Adjusted Odds Ratio] = 4.2, 95% CI [Confidence Interval] 1.6–11.2) and open water containers near the home (AOR = 3.0, 95% CI 1.2–7.5) were risk factors, while long-lasting insecticide treated-net (LLITN) usage (AOR = 0.21, 95% CI 0.05–0.79) was protective. HI and BI were 66/136 (49%) and 147 per 100 homes (147%) respectively, with 151/167 (90%) adult mosquitoes identified as Ae. aegypti. Conclusion The epidemiologic, entomologic, and laboratory investigation confirmed a DF outbreak. Mosquito indices were far above safe thresholds, indicating inadequate vector control. We recommended improved vector surveillance and control programs, including best practices in preserving water and disposal of open containers to reduce Aedes mosquito density.

Risk Factors Associated With Dengue Fever Outbreak in Taiz Governorate, Yemen, 2018: Case-control Study

“…This nding might be due to the fact that mosquito nets are usually used at night, while Aedes aegypti mosquito is active during the day, especially in the early morning and late afternoon. However, this result is dissimilar to two studies in Ethiopia and one in Kenya [3,4,18]. Furthermore, our nding is similar to studies in Ethiopia [4] and Malaysia [16] reported that wearing long clothes is found to be protective and reduces the risk of DF infection, but dissimilar to study in Ethiopia [3].…”

“…Our ndings revealed that there isn't a signi cant association between not covering water containers and getting DF infection. Similar ndings were reported in studies from Ethiopia and India [4,17], but dissimilar to previous studies in Al Hodeidah governorate and Vietnam [1,2].…”

“…Our result is in agreement with the fact that mosquito repellent is a protective measure against DF infection and showed that people who do not use mosquito repellents are at higher risk of getting infection with DF. These ndings are consistent with studies in India, Kenya and Pakistan [17,18,19] and inconsistent with two studies in Ethiopia and others studies in Malaysia and China [3,4,16,20].…”

“…Globally, DF incidence has increased 30-fold over the last 50 years, with increasing geographic expansion to new countries [3,4]. DF is endemic throughout the tropics and sub-tropics with 3.5-4.1 billion people (approximately 53% of the global population) is currently at risk of dengue virus infection [4]. Nearly 390 million cases were reported annually from 120 countries [5].…”

“…Nearly 390 million cases were reported annually from 120 countries [5]. The majority is in Asia, followed by Africa and the Americas [4]. In 2020, dengue affected several countries, with an increased number of cases in Bangladesh, Brazil, Ecuador, India, Indonesia, Maldives, Mauritania, Mayotte (Fr), Nepal, Singapore, Sri Lanka, Sudan, Thailand, Timor-Leste and Yemen [6].…”