Serological evidence of dengue fever and its associated factors in health facilities in the Borena Zone, South Ethiopia

Epidemiology of arboviruses in humans and livestock in Ethiopia: a systematic review and meta-analysis

BACKGROUND

Arbovirus infections are a global public health threat, accounting for approximately 73% of the total emerging and re-emerging human infections, where the burden is worsened in sub-Saharan Africa, including Ethiopia. However, the surveillance system has been still challenged, and their burden and magnitude are not well estimated due to underestimates of true arbovirus burdens by passive case detections. To support targeted evidence-based public health decision-making, comprehensive evidence of arbovirus prevalence is crucial. Thus, the aim of this study was to assess the prevalence of arboviruses in humans and livestock in Ethiopia.

METHOD

Articles were extensively searched in bibliographic databases and gray literatures using entry terms or phrases. PRISMA 2020 flow diagram was used and data among studies meeting eligibility criteria extracted in MS Excel sheet and exported into STATA-17 software for analysis. A random-effects model was used to compute the pooled magnitude of arboviruses in humans and livestock. The heterogeneity was quantified using the I2 value. Publication bias was assessed using a funnel plot and Egger's test. Sensitivity analysis, subgroup analysis and meta-regression were performed to explore heterogeneity.

RESULT

Of the 1957 studies identified, 39 human and 6 livestock studies were eligible for meta-analysis. The overall pooled sero-epidemiology of arboviruses in humans using anti-IgG and anti-IgM was 15.43% (95% CI: 12.11-18.76) and 10.04% (95% CI: 6.46-13.62), respectively. The molecular prevalence of arboviruses in humans was 38.42% (95% CI: 21.77-55.08). The pooled prevalence of arboviruses in livestock was 15.77% (95% CI: 0.45, 31.08). Dengue virus, Yellow fever virus, Zika virus, Rift valley fever, West Nile virus, and chikungunya virus in humans and Rift valley fever, West Nile virus, and Schmallenberg virus in livestock were reported.

CONCLUSION

The magnitude of arboviruses in humans and livestock in Ethiopia alarms the need for immediate multi-sectoral interventions such as strengthening laboratory diagnostic capacities, undertaking an integrated regular national surveillance, and implementation of one-health initiatives and a planetary health approach.

Resting habitat, blood meal source and viral infection rate of Aedes aegypti (Diptera: Culicidae) in the Southern Afar Region of Ethiopia

BACKGROUND

Knowledge of Aedes species distribution, preference to feed on humans, and susceptibility to viruses is crucial in preventing transmission of Aedes-transmitted viruses. This study aimed to determine resting behavior, blood sources, and viral infection status of Aedes aegypti in Awash Sebat, Awash Arba, and Werer towns of Afar Region.

METHODS

Adult mosquitoes were collected using a Prokopack aspirator between 8:00-14:00 and 15:00-18:00 h both indoor and outdoor of the house. The mosquitoes were sorted by sex, date of collection, collection places, and abdominal status and identified by species/genus using standard keys. Blood meal sources and dengue virus and chikungunya virus infection status of Ae. aegypti were determined using ELISA and RT-qPCR respectively.

RESULT

A total of 2,745 adult mosquitoes comprising the genera Aedes (1433; 52.2%) Culex (1292; 47.1%) and Anopheles (20; 0.7%) were collected. The proportion of female Ae. aegypti in Awash Sebat (611; 36%) was highest as compared to females Ae. aegypti in Awash Arba (172; 33.8%), and in Werer (59; 11%). A higher proportion of outdoor resting of Ae. aegypti was caught from tyres rather than other indoor and outdoor locations (314; 37.29%) (X2 27.374, df = 12; p = 0.007). Seasonal and monthly variation was observed in Ae. aegypti collection, where the wet season and the months of August 2022, September 2022, and October 2022 had high Ae aegypti density. The overall human blood and bovine blood indices of Ae. aegypti were 53/145 (36.6%) and 18/145 (12.4%), respectively. Furthermore, dengue and chikungunya viruses were not detected from the Ae. aegypti examined.

CONCLUSION

The majority of Ae. aegypti collections were made during the wet season from outdoor resting sites, particularly from tyres. Thus, outdoor targeted management of Ae. aegypti is recommended as a strategy particularly tyre removal during the wet season, to reduce resting and proliferation of Ae. aegypti and hence prevent the risks of Aedes-borne disease transmission.

Seroprevalence and hematological profile of dengue among healthy inhabitants of Mayo Kebbi province: South of Tchad

Introduction

Dengue is one of the most serious and rapidly spreading major mosquito borne diseases in the world. Despite many acute febrile illnesses in Tchad, the burden of illness due to dengue in the country is largely unknown. Hence, the present study aimed to determine the seroprevalence of dengue viral (DENV) infection and its association with hematological parameters.

Method

A cross sectional study was carried out in Bongor Provincial Hospital. Blood samples were collected from each participant and were used to determine the hematological profile and to diagnose the presence of DENV infection. A total of 130 participants were enrolled in the study. Among these, 114 (87.7%) were diagnosed positive for DENV infection.

Results

The majority of the positive cases were of the age group 21 to 40 years old. Leukocytosis was the most common hematological parameter affecting 120 (92.3%) of them followed by anemia and thrombocytopenia affecting 69 (53.1%) and 16 (12.3%) of them, respectively, and then lymphocytosis affecting 5 (3.8%) of them. No case of leukopenia was recorded.

Discussion

The seroprevalence rate among participants suggests that the dengue virus is in circulation in Mayo Kebbi province: south of Tchad. The abnormal hematological parameters may contribute to the severity of the infection like the incidence of bleeding in the case of thrombocytopenia.

A dengue virus infection in Ethiopia: a systematic review and meta-analysis

BACKGROUND

Dengue is caused by a positive-stranded RNA virus called dengue virus, which is spread by Aedes mosquito species. It is a fast-growing acute febrile disease with potentially lethal consequences that is a global public health problem, mostly in tropical and subtropical countries. In Ethiopia, dengue fever is understudied, although the virus is still being transmitted and viral infection rates are rising. This systematic review and meta-analysis was aimed at estimating the pooled prevalence of DENV infection in Ethiopia.

METHODS

A literature search was done on the PubMed, Hinari and Google Scholar databases to identify studies published before July, 2023. Random effects and fixed effects models were used to estimate the pooled prevalence of all three markers. The Inconsistency Index was used to assess the level of heterogeneity.

RESULTS

A total of 11 studies conducted on suspected individuals with dengue fever and acutely febrile participants were included in this review. The majority of the studies had a moderate risk of bias and no study had a high risk of bias. A meta-analysis estimated a pooled IgG prevalence of 21% (95% CI: 19-23), a pooled IgM prevalence of 9% (95%CI: 4-13) and a pooled DENV-RNA prevalence of 48% (95% CI: 33-62). There is evidence of possible publication bias in IgG but not in the rest of the markers.

CONCLUSION

Dengue is prevalent among the dengue fever suspected and febrile population in Ethiopia. Healthcare providers, researchers and policymakers should give more attention to dengue fever.

Epidemiology, biology, pathogenesis, clinical manifestations, and diagnosis of dengue virus infection, and its trend in Ethiopia: a comprehensive literature review

Dengue fever is a dengue virus infection, emerging rapidly and posing public health threat worldwide, primarily in tropical and subtropical countries. Nearly half of the world's population is now at risk of contracting the dengue virus, including new countries with no previous history-like Ethiopia. However, little is known about the epidemiology and impact of the disease in different countries. This is especially true in countries, where cases have recently begun to be reported. This review aims to summarize epidemiology, biology, pathogenesis, clinical manifestations, and diagnosis of dengue virus infection and its trend in Ethiopia. It may help countries, where dengue fever is not yet on the public health list-like Ethiopia to alert healthcare workers to consider the disease for diagnosis and treatment. The review retrieved and incorporated 139 published and organizational reports showing approximately 390 million new infections. About 100 million of these infections develop the clinical features of dengue, and thousands of people die annually from severe dengue fever in 129 countries. It is caused by being bitten by a dengue virus-infected female mosquito, primarily Aedes aegypti and, lesser, Ae. albopictus. Dengue virus is a member of the Flavivirus genus of the Flaviviridae family and has four independent but antigen-related single-stranded positive-sense RNA virus serotypes. The infection is usually asymptomatic but causes illnesses ranging from mild febrile illness to fatal dengue hemorrhagic fever or shock syndrome. Diagnosis can be by detecting the virus genome using nucleic acids amplification tests or testing NS1 antigen and/or anti-dengue antibodies from serum, plasma, circulating blood cells, or other tissues. Dengue cases and outbreaks have increased in recent decades, with a significant public health impact. Ethiopia has had nearly annual outbreaks since 2013, devastating an already fragmented health system and economy. Standardization of medication, population-level screening for early diagnosis and prompt treatment, and minimization of mosquito bites reduce overall infection and mortality rates.

Epidemiological, Entomological, and Climatological Investigation of the 2019 Dengue Fever Outbreak in Gewane District, Afar Region, North-East Ethiopia

Dengue Fever (DF) is an important arthropod-borne viral infection that has repeatedly occurred as outbreaks in eastern and northeastern Ethiopia since 2013. A cross-sectional epidemiological outbreak investigation was carried out from September to November 2019 on febrile patients (confirmed malaria negative) who presented with suspected and confirmed DF at both public and private health facilities in Gewane District, Afar Region, northeastern Ethiopia. Entomological investigation of containers found in randomly selected houses belonging to DF-positive patients was undertaken to survey for the presence of Aedes larvae/pupae. A total of 1185 DF cases were recorded from six health facilities during the 3-month study period. The mean age of DF cases was 27.2 years, and 42.7% of cases were female. The most affected age group was 15−49 years old (78.98%). The total case proportions differed significantly across age groups when compared to the population distribution; there were approximately 15% and 5% higher case proportions among those aged 15−49 years and 49+ years, respectively. A total of 162 artificial containers were inspected from 62 houses, with 49.4% found positive for Aedes aegypti larva/pupae. Aedes mosquitoes were most commonly observed breeding in plastic tanks, tires, and plastic or metal buckets/bowls. World Health Organization entomological indices classified the study site as high risk for dengue virus outbreaks (House Index = 45.2%, Container Index = 49.4%, and Breteau Index = 129). Time series climate data, specifically rainfall, were found to be significantly predictive of AR (p = 0.035). Study findings highlight the importance of vector control to prevent future DF outbreaks in the region. The scarcity of drinking water and microclimatic conditions may have also contributed to the occurrence of this outbreak.

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

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.