Biology subjects

Massebo, F.

Publications and source records attributed to Massebo, F..

3 recordsLinked to original sources

bioRxiv2024

Trypanosome infection rate and blood-feeding patterns of tsetse fly in an area with a recent human African trypanosomiasis outbreak in Southwest Ethiopia

IntroductionThe recent outbreak of Human African Trypanosomiasis (HAT) in the Deme River Valley, Ethiopia, has highlighted the need for more comprehensive data on the infection rate of trypanosomes and the feeding patterns of tsetse. The study aimed to assess the infection rate of trypanosomes and the feeding patterns of tsetse flies collected using various attractants. Methodology/principal findingsTraps with various bait odors were placed randomly and rotated monthly. Anesthetized and recently deceased tsetse flies were examined to determine the infection rate using microscopy, and the origins of the blood meal were determined using the polymerase chain reaction technique. We used the Poisson regression model to analyze count data and the binary logistic regression model to assess binary outcomes (positive or negative) and infection rates. Of the 1208 tsetse flies captured, 751 (62.2%) were Glossina pallidipes, while 457 (37.8%) were Glossina fuscipes fuscipes. The trypanosome infection rate in tsetse flies was 17.1% (95% CI: 14.2-20.3). Of the 103 positive tsetse flies, 66% were infected with T. congolense, 24.3% with T. vivax, 1.9% with T. brucei, and 7.8% with either T. congolense or T. brucei (the immature stages identified in the mid-gut). The infection rate of trypanosomes in G. pallidipes (19. 6%) was higher than that of G. f. fuscipes (12.8%). Traps using a combination of cow urine and acetone captured tsetse flies with a higher infection rate of trypanosomes (21.2%), followed by acetone alone (18.9%), cow urine alone (12.2%), and traps without bait (6.1%). Of 107 freshly fed tsetse flies, 23.4% were fed to dogs, 8.4% to humans, 7.5% to cattle, and 4.7% to goats, including the mixed blood meals. Conclusions/main suggestionsThe high trypanosome infection rate in tsetse flies indicates an increased risk of trypanosomiasis infection. Although tsetse flies seem attracted to dogs, the potential risk of human exposure must also be considered. Further research is needed to understand the role of dogs in parasite transmission. Authors summaryAfrican Animal Trypanosomosis (AAT) is a significant issue in animal production in sub-Saharan African countries, including Ethiopia. The recent outbreak of HAT in the Deme River Valley, Ethiopia, has emphasized the need for more comprehensive data on the infection rate of trypanosomes and the feeding patterns of tsetse flies to understand human exposure. The current study revealed a high infection rate of trypanosomes in tsetse flies, with T. congolense having the highest prevalence, followed by T. vivax. Public concern is related to the T. brucei complex, as it is possibly the strain that causes HAT. Combining cow urine with acetone could significantly improve tsetse trapping and be used in tsetse suppression programs to reduce the risks of infectious tsetse flies. Analysis of the blood meal origins revealed that tsetse flies feed on various vertebrate animals, including dogs and humans. Urgent research is needed to understand the role of dogs in parasite transmission. It is recommended that large-scale tsetse control be implemented using baits such as fermented cow urine in combination with acetone for tsetse suppression.

zoology↗

bioRxiv2019

Feeding behavior and activity of Phlebotomus pedifer and potential reservoir hosts of Leishmania aethiopica in southwestern Ethiopia.

BackgroundCutaneous leishmaniasis (CL) is a major public health concern in Ethiopia. However, knowledge about the complex zoonotic transmission cycle is limited, hampering implementation of control strategies. We explored the feeding behavior and activity of the vector (Phlebotomus pedifer) and established the role of livestock in CL transmission. MethodsBlood meal origins of engorged sand flies were determined by sequencing host DNA. A host choice experiment was performed to assess the feeding preference of P. pedifer when humans and hyraxes are equally accessible. Ear and nose biopsies from goats and bovines were screened for the presence of Leishmania parasites. Sand flies were captured indoor and outdoor with human landing catches (HLC) and CDC light traps to determine at which time and where P. pedifer is mostly active. Principal findingsA total of 180 sand flies were found to bite hosts of 12 genera. Humans were the predominant blood meal source (59.4%, p < 0.001) in all habitats, even in caves, where hyraxes are abundant. Only 10.6% of the sand flies fed on hyraxes based on the blood meal analysis, but the host choice experiment revealed that sand flies have a significant preference for feeding on hyraxes over humans (p = 0.009) when hosts are equally accessible. Only a single goat nose biopsy from 412 animal samples was found with Leishmania RNA. We found that P. pedifer is predominantly endophagic (p = 0.003), but occurs both indoors and outdoors. A substantial amount of sand flies was active in the early evening, which increased over time reaching its maximum around midnight. ConclusionWe indicate that Leishmania transmission in southwestern Ethiopia is, in contrast to earlier suggestions, likely mainly anthroponotic and that livestock does not play a role in transmission. Combined indoor and outdoor vector control measures at night are required for efficient vector control. Author summaryCutaneous leishmaniasis is a major public health problem in Ethiopia. It is caused by Leishmania aethiopica protozoa that are transmitted when female sand flies take a blood meal. Hyraxes are assigned as the reservoirs of the infection, because many were found infected with Leishmania. There is very limited knowledge about the behavior of sand flies and other potential hosts of the infection. However, this information is a prerequisite for disease control, which is currently hampered. In this study, we found that humans are likely the main source of the infection and that the role of hyraxes in disease transmission needs further investigation to decide whether they should be included in control programs. Livestock appears not play a role in transmission, even though sand flies like to feed on them. We also show that sand flies are active indoors and outdoors, but have a preference for feeding inside human dwellings and that they are mostly active around midnight. Overall, we conclude that disease prevention and control should emphasize on human protection by applying vector control indoors, at night.

ecology↗

bioRxiv2018

A community-level investigation of the yellow fever virus outbreak in South Omo Zone, South-West Ethiopia, 2012-2014

BackgroundA yellow fever (YF) outbreak occurred in South Omo Zone, Ethiopia in 2012-2014. This study aimed to analyse historical epidemiological data, to assess the risk for future YF outbreaks through entomological surveillance, including mosquito species identification and molecular screening for arboviruses, and finally to determine the knowledge, attitudes and current preventative practices within the affected communities.\n\nMethodology/Principal FindingsFrom October 2012 to March 2014, 165 cases and 62 deaths were reported, principally in rural areas of South Ari region (83.6%), south-west Ethiopia. The majority of patients were 15-44 years old (74.5%) and most case deaths were males (76%). Between June and August 2017, 688 containers were sampled from across 177 households to identify key breeding sites for Aedes mosquitoes. Ensete ventricosum (\"false banana\") was identified as the primary natural breeding site, and clay pots outside the home as the most productive artificial breeding site. Entomological risk indices from the majority of sites were classified as \"high risk\" for future outbreaks under current World Health Organization criteria. Adult trapping resulted in the identification of members of the Aedes simpsoni complex in and around households. Screening of adult females revealed no detection of yellow fever virus (YFV) or other arboviruses. 88% of 177 participants had heard of YF, however many participants easily confused transmission and symptoms of YF with malaria, which is also endemic in the area.\n\nConclusions/SignificanceStudy results emphasise the need for further entomological studies to improve our understanding of local vector species and transmission dynamics. Disease surveillance systems and in-country laboratory capacity also need to be strengthened to facilitate more rapid responses to future YF outbreaks.\n\nAuthor SummaryDespite the availability of a highly effective vaccine, yellow fever virus (YFV) remains an important public health problem across Africa and South America due to its high case-fatality rate. This study aimed to assess and reduce the risk for future outbreaks. During this study, historical data analysis was conducted to understand the epidemiology of the recent outbreak in 2012-2014. Entomological surveillance was also carried out, including both mosquito species identification and molecular screening for arboviruses, as well as a household survey to understand the knowledge and attitudes towards yellow fever (YF) within the affected areas and to assess community-level practices for YF prevention. We found a high abundance of Aedes simpsoni complex in the context of low vaccination coverage. Community knowledge and practice levels were low for reducing potential breeding sites, highlighting the need for increased dissemination of information to community members on how to reduce their risk of exposure to mosquito vectors of arboviruses.

epidemiology↗