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result(s) for
"Frempong, Kwadwo K."
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Climate-driven models reveal temporal trends in Aedes breeding: implications for outbreak preparedness and control interventions
by
Boakye, Helena A.
,
Akorli, Jewelna
,
Oware, Stephen K. D.
in
Aedes
,
Aedes - growth & development
,
Aedes - physiology
2025
Background
Aedes
-borne arboviral diseases, especially dengue, are on the rise. The global expansion of
Aedes
mosquitoes, driven by changing climatic conditions, has led to the emergence of these diseases in previously non-endemic regions. Effective entomological surveillance, which considers changes in weather conditions, is crucial for the timely detection, emergency preparedness and control of
Aedes-
borne diseases.
Methods
In this study, we collected
Aedes
eggs using ovitraps and estimated peri-domestic larval indices from urban locations over 6 months. Regression models were applied to determine the influence of meteorological factors on
Aedes
breeding and temporal trends in entomological indices pertinent to disease risk prediction.
Results
Ovitraps and larval sampling identified different months as most conducive for
Ae. aegypti
breeding activities, highlighting the impact of sampling method on surveillance and data interpretation for outbreak preparedness. Temperature and wind speed were identified as strong predictors of the entomological indices investigated. Rainfall was not a consistent predictor of
Ae. aegypti
breeding, except when in combination with temperature or wind speed. The presence of unused tyres within the peri-domestic environment was identified as a primary breeding site, but other open receptacles such as discarded cans and broken clay pots, especially in the absence of tyres, also contributed to
Aedes
presence.
Conclusions
Our models demonstrated predictive potential for estimating vector populations and risk of disease outbreaks, which could help in emergency preparedness and the deployment of control measures. Additionally, these models offer a tool for anticipating shifts in vector distribution under changing climate conditions, providing valuable insights for improving disease prevention strategies.
Journal Article
Progress towards lymphatic filariasis elimination in Ghana from 2000-2016: Analysis of microfilaria prevalence data from 430 communities
by
Biritwum, Nana Kwadwo
,
Asiedu, Odame
,
Alomatu, Bright
in
Albendazole
,
Albendazole - therapeutic use
,
Animals
2019
Ghana started its national programme to eliminate lymphatic filariasis (LF) in 2000, with mass drug administration (MDA) with ivermectin and albendazole as main strategy. We review the progress towards elimination that was made by 2016 for all endemic districts of Ghana and analyze microfilaria (mf) prevalence from sentinel and spot-check sites in endemic districts.
We reviewed district level data on the history of MDA and outcomes of transmission assessment surveys (TAS). We further collated and analyzed mf prevalence data from sentinel and spot-check sites.
MDA was initiated in 2001-2006 in all 98 endemic districts; by the end of 2016, 81 had stopped MDA after passing TAS and after an average of 11 rounds of treatment (range 8-14 rounds). The median reported coverage for the communities was 77-80%. Mf prevalence survey data were available for 430 communities from 78/98 endemic districts. Baseline mf prevalence data were available for 53 communities, with an average mf prevalence of 8.7% (0-45.7%). Repeated measurements were available for 78 communities, showing a steep decrease in mean mf prevalence in the first few years of MDA, followed by a gradual further decline. In the 2013 and 2014 surveys, 7 and 10 communities respectively were identified with mf prevalence still above 1% (maximum 5.6%). Fifteen of the communities above threshold are all within districts where MDA was still ongoing by 2016.
The MDA programme of the Ghana Health Services has reduced mf prevalence in sentinel sites below the 1% threshold in 81/98 endemic districts in Ghana, yet 15 communities within 13 districts (MDA ongoing by 2016) had higher prevalence than this threshold during the surveys in 2013 and 2014. These districts may need to intensify interventions to achieve the WHO 2020 target.
Journal Article
Biting Behavior and Molecular Identification of Aedes aegypti (Diptera: Culicidae) Subspecies in Some Selected Recent Yellow Fever Outbreak Communities in Northern Ghana
by
Asoala, Victor
,
Adabie-Gomez, Delphina
,
Chabi, Joseph
in
adults
,
Aedes
,
Aedes - anatomy & histology
2020
Aedes aegypti (L.) (Diptera: Culicidae) is a diurnal feeder that lives in close association with human populations. It is the principal vector of yellow fever, dengue fever and the Zika Virus. Issues of arboviral diseases have been on the ascendency in most countries including Ghana where Aedes mosquito is the main vector of yellow fever. A comparative study of the biting behavior of Ae. aegypti and the identification of subspecies were undertaken using molecular technique. Standard human landing technique was used to collect both indoor and outdoor biting mosquitoes at three zones located in the Upper East (Bolgatanga), Upper West (Nadowli), and Northern (Damongo) Regions of Ghana during the dry and rainy seasons between 0600 and 1800 Greenwich Mean Time (GMT). All collected mosquitoes were identified morphologically using taxonomic keys. random amplified polymorphic DNA polymerase chain reaction was used to categorize Ae. aegypti into subspecies. Adult female Aedes mosquitoes identified formed 62% (n = 1,206) of all female mosquitoes collected. Aedes aegypti 98% and Aedes vittatus 2% were the only Aedes species identified. Bolgatanga recorded the largest number of Ae. aegypti 42%, whereas Nadowli 22% recorded the least. Aedes vittatus was observed in Nadowli. Aedes aegypti exhibited a bimodal biting behavior peaking at 0600–0800 GMT and 1500–1600 h GMT. Molecular findings revealed 69% Ae. aegypti aegypti and 31% Ae. aegypti formosus as the two subspecies (n = 110). This information is important for implementing effective vector control programs in the three regions of the northern Ghana.
Journal Article
Does Increasing Treatment Frequency Address Suboptimal Responses to Ivermectin for the Control and Elimination of River Blindness?
by
Cheke, Robert A.
,
Tetevi, Edward Jenner
,
Osei-Atweneboana, Mike
in
Adult
,
and Commentaries
,
Antiparasitic Agents - administration & dosage
2016
Background. Several African countries have adopted a biannual ivermectin distribution strategy in some foci to control and eliminate onchocerciasis. In 2010, the Ghana Health Service started biannual distribution to combat transmission hotspots and suboptimal responses to treatment. We assessed the epidemiological impact of the first 3 years of this strategy and quantified responses to ivermectin over 2 consecutive rounds of treatment in 10 sentinel communities. Methods. We evaluated Onchocerca volvulus community microfilarial intensity and prevalence in persons aged ≥20 years before the first, second, and fifth (or sixth) biannual treatment rounds using skin snip data from 956 participants. We used longitudinal regression modeling to estimate rates of microfilarial repopulation of the skin in a cohort of 217 participants who were followed up over the first 2 rounds of biannual treatment. Results. Biannual treatment has had a positive impact, with substantial reductions in infection intensity after 4 or 5 rounds in most communities. We identified 3 communities—all having been previously recognized as responding suboptimally to ivermectin—with statistically significantly high microfilarial repopulation rates. We did not find any clear association between microfilarial repopulation rate and the number of years of prior intervention, coverage, or the community level of infection. Conclusions. The strategy of biannual ivermectin treatment in Ghana has reduced O. volvulus microfilarial intensity and prevalence, but suboptimal responses to treatment remain evident in a number of previously and consistently implicated communities. Whether increasing the frequency of treatment will be sufficient to meet the World Health Organization's 2020 elimination goals remains uncertain.
Journal Article
Biting Behavior and Molecular Identification of Aedes aegypti
2020
Aedes aegypti (L.) (Diptera: Culicidae) is a diurnal feeder that lives in close association with human populations. It is the principal vector of yellow fever, dengue fever and the Zika Virus. Issues of arboviral diseases have been on the ascendency in most countries including Ghana where Aedes mosquito is the main vector of yellow fever. A comparative study of the biting behavior of Ae. aegypti and the identification of subspecies were undertaken using molecular technique. Standard human landing technique was used to collect both indoor and outdoor biting mosquitoes at three zones located in the Upper East (Bolgatanga), Upper West (Nadowli), and Northern (Damongo) Regions of Ghana during the dry and rainy seasons between 0600 and 1800 Greenwich Mean Time (GMT). All collected mosquitoes were identified morphologically using taxonomic keys. random amplified polymorphic DNA polymerase chain reaction was used to categorize Ae. aegypti into subspecies. Adult female Aedes mosquitoes identified formed 62% (n = 1,206) of all female mosquitoes collected. Aedes aegypti 98% and Aedes vittatus 2% were the only Aedes species identified. Bolgatanga recorded the largest number of Ae. aegypti 42%, whereas Nadowli 22% recorded the least. Aedes vittatus was observed in Nadowli. Aedes aegypti exhibited a bimodal biting behavior peaking at 0600-0800 GMT and 1500-1600 h GMT. Molecular findings revealed 69% Ae. aegypti aegypti and 31% Ae. aegypti formosus as the two subspecies (n = 110). This information is important for implementing effective vector control programs in the three regions of the northern Ghana.
Journal Article
Indication of Risk of Mother-to-Child Toxoplasma gondii Transmission in the Greater Accra Region of Ghana
2016
Objectives
Congenital infection with
Toxoplasma gondii
is known to result in neurological and brain disorders including ophthalmic disorders later in life. Research in Ghana revealed high sero-prevalence among pregnant women and eye patients. This study determines the risk of congenital transmission of
T. gondii
infection in Accra, Ghana.
Methods
One hundred consented pregnant women aged 18–45 years (mean 29.85 ± 5.76) participated. Venous blood and tissue samples were taken from the maternal side of each placenta after delivery. Cord blood samples were also taken after they were separated from the infants. Finger-prick blood was taken from infants of participating women at 2 or 6 weeks post-natal. ELISA was used to detect
T. gondii
antibodies in all blood samples while Nested-PCR was used to detect
T. gondii
DNA from placental tissues. Data was analysed using SPSS v. 16.
Results
Overall, 37.6 % of maternal blood, 39.5 % of umbilical cord blood, and 57.5 % of post-natal infant blood were positive for anti-
T. gondii
IgG. No anti-
T. gondii
IgM was detected in any of those samples.
Toxoplasma gondii
DNA was detected in 39.8 % of placental tissue samples. Strong association was observed in the occurrence of placental
T. gondii
DNA and anti-
T. gondii
IgG positive women (ø = 0.810,
p
< 0.00001) as well as high Relative risk shown in the likelihood of foetal exposure to infection in latently-infected women (RR 10.39; CI 4.47–24.17;
p
< 0.00001).
Conclusions for Practice
The presence of anti-
T. gondii
IgG antibodies only, and
T. gondii
DNA in placental tissues indicate the women might have been infected early during the pregnancy, placing about 39.8 % of the babies at risk. These results can strongly influence policy to screen and treat pregnant women for
T. gondii
infection.
Journal Article
Implementing a community vector collection strategy for monitoring vector-borne diseases in Ghana
2019
Background: Monitoring vector-borne diseases requires sampling of very large numbers of disease vectors in order to corroborate infections in the human population. This can be challenging, as current vector collection tools are either inefficient, or expensive to implement from a public health perspective. To circumvent this challenge, this study compared a community vector collection strategy using a double-netted mosquito collection method (a tent trap (TT)) to the traditional human landing collection (HLC) method in three communities in lymphatic filariasis-endemic districts in Ghana. Methods: Following community entry and sensitization, community volunteers appointed by the community leaders were trained in the mosquito collection and storage methods and provided with supplies for mosquito collection over a 7-month period. They were visited occasionally by the study team to retrieve the mosquito samples for identification. The collectors were also assessed to evaluate their perspectives on using community vector collectors for monitoring vector-borne diseases. Results: The results of the study indicated that the TT method collected significantly more mosquitoes (63%) over the collection period than HLC (37%). Thus, the TTs were observed to be performing relatively better than the HLC (P<0.001). The collectors knew the importance of mosquitoes in transmitting diseases, could identify the main diseases that were locally transmitted within their communities. They appreciated the involvement of the community in the collection as this enhanced community ownership of the programme as well as providing some financial incentives to those directly involved in the collection. Conclusions: The study revealed that use of community volunteers for the collection of mosquitoes for xenomonitoring purposes can be a viable strategy in the monitoring of vector-borne diseases. However, further development of the strategies and assessments of the costs involved will be required to make this a sustainable approach to monitoring vector-borne disease interventions and enhance community ownership of the programmes.
Journal Article
Implementing a community vector collection strategy for monitoring vector-borne diseases in Ghana
2019
Background: Monitoring vector-borne diseases requires sampling of very large numbers of disease vectors in order to corroborate infections in the human population. This can be challenging, as current vector collection tools are either inefficient, or expensive to implement from a public health perspective. To circumvent this challenge, this study compared a community vector collection strategy using a double-netted mosquito collection method (a tent trap (TT)) to the traditional human landing collection (HLC) method in three communities in lymphatic filariasis-endemic districts in Ghana. Methods: Following community entry and sensitization, community volunteers appointed by the community leaders were trained in the mosquito collection and storage methods and provided with supplies for mosquito collection over a 7-month period. They were visited occasionally by the study team to retrieve the mosquito samples for identification. The collectors were also assessed to evaluate their perspectives on using community vector collectors for monitoring vector-borne diseases. Results: The results of the study indicated that the TT method collected significantly more mosquitoes (63%) over the collection period than HLC (37%). Thus, the TTs were observed to be performing relatively better than the HLC ( P <0.001). The collectors knew the importance of mosquitoes in transmitting diseases, could identify the main diseases that were locally transmitted within their communities. They appreciated the involvement of the community in the collection as this enhanced community ownership of the programme as well as providing some financial incentives to those directly involved in the collection. Conclusions: The study revealed that use of community volunteers for the collection of mosquitoes for xenomonitoring purposes can be a viable strategy in the monitoring of vector-borne diseases. However, further development of the strategies and assessments of the costs involved will be required to make this a sustainable approach to monitoring vector-borne disease interventions and enhance community ownership of the programmes.
Journal Article
Implementing a community vector collection strategy for monitoring vector-borne diseases in Ghana
2019
Background: Monitoring vector-borne diseases requires sampling of very large numbers of disease vectors in order to corroborate infections in the human population. This can be challenging, as current vector collection tools are either inefficient, or expensive to implement from a public health perspective. To circumvent this challenge, this study compared a community vector collection strategy using a double-netted mosquito collection method (a tent trap (TT)) to the traditional human landing collection (HLC) method in three communities in lymphatic filariasis-endemic districts in Ghana. Methods: Following community entry and sensitization, community volunteers appointed by the community leaders were trained in the mosquito collection and storage methods and provided with supplies for mosquito collection over a 7-month period. They were visited occasionally by the study team to retrieve the mosquito samples for identification. The collectors were also assessed to evaluate their perspectives on using community vector collectors for monitoring vector-borne diseases. Results: The results of the study indicated that the TT method collected significantly more mosquitoes (63%) over the collection period than HLC (37%). Thus, the TTs were observed to be performing relatively better than the HLC ( P <0.001). The collectors knew the importance of mosquitoes in transmitting diseases, could identify the main diseases that were locally transmitted within their communities. They appreciated the involvement of the community in the collection as this enhanced community ownership of the programme as well as providing some financial incentives to those directly involved in the collection. Conclusions: The study revealed that use of community volunteers for the collection of mosquitoes for xenomonitoring purposes can be a viable strategy in the monitoring of vector-borne diseases. However, further development of the strategies and assessments of the costs involved will be required to make this a sustainable approach to monitoring vector-borne disease interventions and enhance community ownership of the programmes.
Journal Article
Progress towards lymphatic filariasis elimination in Ghana from 2000-2016: analysis of microfilaria prevalence data from 430 communities
by
Asiedu, Odame
,
Kontoroupis, Periklis
,
Bright Alomatu
in
Albendazole
,
Epidemiology
,
Filariasis
2018
Background Ghana started its national programme to eliminate lymphatic filariasis (LF) in 2000, with mass drug administration (MDA) with ivermectin and albendazole as main strategy. We review the progress towards elimination that was made by 2016 for all endemic districts of Ghana and analyze mf prevalence from sentinel and spot-check sites in endemic districts. Methods We reviewed district level data on the history of MDA and outcomes of transmission assessment surveys (TAS). We further collated and analyzed microfilaria (mf) prevalence data from sentinel and spot-check sites. Results MDA was initiated in 2001-2006 in all 98 endemic districts; by the end of 2016, 81 had stopped MDA after passing TAS and after an average of 11 rounds of treatment (range 8 – 14 rounds). The median reported coverage for the communities was 77-80%. Mf prevalence survey data were available for 430 communities from 78/98 endemic districts. Baseline mf prevalence data were available for 53 communities, with an average mf prevalence of 8.7% (0 - 45.7%). Repeated measurements were available for 78 communities, showing a steep decrease in mean mf prevalence in the first few years of MDA, followed by a gradual further decline. In the 2013 and 2014 surveys, 7 and 10 communities respectively were identified with mf prevalence still above 1% (maximum 5.6%). Two stopped MDA in 2015 and 2016 respectively, while the rest of the 15 communities above threshold are all within 13/17 districts where MDA is still ongoing. Conclusions The MDA programme of the Ghana Health Services has reduced mf prevalence in sentinel sites below the 1% threshold in 81/98 endemic districts in Ghana, yet 15 communities within 13 districts (MDA ongoing) had higher prevalence than this threshold during the surveys in 2013 and 2014. These districts may need to intensify interventions to achieve the WHO 2020 target.