The Impact of Bushmeat Hunting on the Primates of Bioko Island, Equatorial Guinea

AbstractBackgroundMalaria elimination is the goal for Bioko Island, Equatorial Guinea. Intensive interventions implemented since 2004 have reduced prevalence, but progress has stalled in recent years. A challenge for elimination has been malaria infections in residents acquired during travel to mainland Equatorial Guinea. We quantify how off-island contributes to remaining malaria prevalence on Bioko Island, and investigate the potential role of a pre-erythrocytic vaccine in making further progress towards elimination.MethodsWe simulated malaria transmission on Bioko Island using a model calibrated based on data from the Malaria Indicator Surveys (MIS) from 2015-2018, including detailed travel histories and malaria positivity by rapid-diagnostic tests (RDTs), as well as geospatial estimates of malaria prevalence. Mosquito population density was adjusted to fit local transmission, conditional on importation rates under current levels of control and within-island mobility. We evaluated the impact of two pre-erythrocytic vaccine distribution strategies: mass treat and vaccinate, and prophylactic vaccination for off-island travelers. We propagated uncertainty through the model through an ensemble of simulations fit to the Bayesian joint posterior probability distribution of the geospatial prevalence estimates.ResultsThe simulations suggest that in Malabo, an urban city containing 80% of the population, there are some pockets of residual transmission, but a large proportion of prevalence is attributable to malaria importation by travelers. Outside of Malabo, prevalence was mainly attributable to local transmission. We assess the uncertainty in the local transmission vs. importation to be lowest within Malabo and highest outside. Using a pre-erythrocytic vaccine to protect travelers would have larger benefits than using the vaccine to protect residents of Bioko Island from local transmission. In simulations, mass treatment and vaccination had short-lived benefits, as malaria prevalence returned to current levels as the vaccine’s efficacy waned. Prophylactic vaccination of travelers resulted in longer-lasting reductions in prevalence. These projections were robust to underlying uncertainty in prevalence estimates.ConclusionsThe modeled outcomes suggest that the volume of malaria cases imported from the mainland is a partial driver of continued endemic malaria on Bioko Island, and that continued elimination efforts on must account for human travel activity.

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Quantifying Malaria Acquired During Travel and Its Role in Malaria Elimination on Bioko Island

10.21203/rs.3.rs-522727/v1 ◽

2021 ◽

Author(s):

Daniel T Citron ◽

Carlos A Guerra ◽

Guillermo A García ◽

Sean L Wu ◽

Katherine E Battle ◽

...

Keyword(s):

Malaria Elimination ◽

Malaria Prevalence ◽

Equatorial Guinea ◽

Bioko Island ◽

Posterior Probability Distribution ◽

Urban City ◽

Prevalence Estimates ◽

Prophylactic Vaccination ◽

The Impact ◽

Local Transmission

Abstract Background Malaria elimination is the goal for Bioko Island, Equatorial Guinea. Intensive interventions implemented since 2004 have reduced prevalence, but progress has stalled in recent years. A challenge for elimination has been malaria infections in residents acquired during travel to mainland Equatorial Guinea. We quantify how off-island contributes to remaining malaria prevalence on Bioko Island, and investigate the potential role of a pre-erythrocytic vaccine in making further progress towards elimination. Methods We simulated malaria transmission on Bioko Island using a model calibrated based on data from the Malaria Indicator Surveys (MIS) from 2015-2018, including detailed travel histories and malaria positivity by rapid-diagnostic tests (RDTs), as well as geospatial estimates of malaria prevalence. Mosquito population density was adjusted to fit local transmission, conditional on importation rates under current levels of control and within-island mobility. We evaluated the impact of two pre-erythrocytic vaccine distribution strategies: mass treat and vaccinate, and prophylactic vaccination for off-island travelers. We propagated uncertainty through the model through an ensemble of simulations fit to the Bayesian joint posterior probability distribution of the geospatial prevalence estimates. Results The simulations suggest that in Malabo, an urban city containing 80\% of the population, there are some pockets of residual transmission, but a large proportion of prevalence is attributable to malaria importation by travelers. Outside of Malabo, prevalence was mainly attributable to local transmission. We assess the uncertainty in the local transmission vs. importation to be lowest within Malabo and highest outside. Using a pre-erythrocytic vaccine to protect travelers would have larger benefits than using the vaccine to protect residents of Bioko Island from local transmission. In simulations, mass treatment and vaccination had short-lived benefits, as malaria prevalence returned to current levels as the vaccine's efficacy waned. Prophylactic vaccination of travelers resulted in longer-lasting reductions in prevalence. These projections were robust to underlying uncertainty in prevalence estimates. Conclusions The modeled outcomes suggest that the volume of malaria cases imported from the mainland is a partial driver of continued endemic malaria on Bioko Island, and that continued elimination efforts on must account for human travel activity.

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Quantifying malaria acquired during travel and its role in malaria elimination on Bioko Island

Malaria Journal ◽

10.1186/s12936-021-03893-x ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Daniel T. Citron ◽

Carlos A. Guerra ◽

Guillermo A. García ◽

Sean L. Wu ◽

Katherine E. Battle ◽

...

Keyword(s):

Malaria Elimination ◽

Malaria Prevalence ◽

Equatorial Guinea ◽

Bioko Island ◽

Posterior Probability Distribution ◽

Urban City ◽

Prevalence Estimates ◽

Prophylactic Vaccination ◽

The Impact ◽

Local Transmission

Abstract Background Malaria elimination is the goal for Bioko Island, Equatorial Guinea. Intensive interventions implemented since 2004 have reduced prevalence, but progress has stalled in recent years. A challenge for elimination has been malaria infections in residents acquired during travel to mainland Equatorial Guinea. The present article quantifies how off-island contributes to remaining malaria prevalence on Bioko Island, and investigates the potential role of a pre-erythrocytic vaccine in making further progress towards elimination. Methods Malaria transmission on Bioko Island was simulated using a model calibrated based on data from the Malaria Indicator Surveys (MIS) from 2015 to 2018, including detailed travel histories and malaria positivity by rapid-diagnostic tests (RDTs), as well as geospatial estimates of malaria prevalence. Mosquito population density was adjusted to fit local transmission, conditional on importation rates under current levels of control and within-island mobility. The simulations were then used to evaluate the impact of two pre-erythrocytic vaccine distribution strategies: mass treat and vaccinate, and prophylactic vaccination for off-island travellers. Lastly, a sensitivity analysis was performed through an ensemble of simulations fit to the Bayesian joint posterior probability distribution of the geospatial prevalence estimates. Results The simulations suggest that in Malabo, an urban city containing 80% of the population, there are some pockets of residual transmission, but a large proportion of infections are acquired off-island by travellers to the mainland. Outside of Malabo, prevalence was mainly attributable to local transmission. The uncertainty in the local transmission vs. importation is lowest within Malabo and highest outside. Using a pre-erythrocytic vaccine to protect travellers would have larger benefits than using the vaccine to protect residents of Bioko Island from local transmission. In simulations, mass treatment and vaccination had short-lived benefits, as malaria prevalence returned to current levels as the vaccine’s efficacy waned. Prophylactic vaccination of travellers resulted in longer-lasting reductions in prevalence. These projections were robust to underlying uncertainty in prevalence estimates. Conclusions The modelled outcomes suggest that the volume of malaria cases imported from the mainland is a partial driver of continued endemic malaria on Bioko Island, and that continued elimination efforts on must account for human travel activity.

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Incidence of Plasmodium falciparum malaria infection in 6-month to 45-year-olds on selected areas of Bioko Island, Equatorial Guinea

Malaria Journal ◽

10.1186/s12936-021-03850-8 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Vicente Urbano Nsue Ndong Nchama ◽

Ali Hamad Said ◽

Ali Mtoro ◽

Gertrudis Owono Bidjimi ◽

Marta Alene Owono ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Malaria Control ◽

Malaria Infection ◽

Age Groups ◽

Control Measures ◽

Equatorial Guinea ◽

Safety And Efficacy ◽

Bioko Island ◽

Malaria Vaccines

Abstract Background Extensive malaria control measures have been implemented on Bioko Island, Equatorial Guinea over the past 16 years, reducing parasite prevalence and malaria-related morbidity and mortality, but without achieving elimination. Malaria vaccines offer hope for reducing the burden to zero. Three phase 1/2 studies have been conducted successfully on Bioko Island to evaluate the safety and efficacy of whole Plasmodium falciparum (Pf) sporozoite (SPZ) malaria vaccines. A large, pivotal trial of the safety and efficacy of the radiation-attenuated Sanaria® PfSPZ Vaccine against P. falciparum is planned for 2022. This study assessed the incidence of malaria at the phase 3 study site and characterized the influence of socio-demographic factors on the burden of malaria to guide trial design. Methods A cohort of 240 randomly selected individuals aged 6 months to 45 years from selected areas of North Bioko Province, Bioko Island, was followed for 24 weeks after clearance of parasitaemia. Assessment of clinical presentation consistent with malaria and thick blood smears were performed every 2 weeks. Incidence of first and multiple malaria infections per person-time of follow-up was estimated, compared between age groups, and examined for associated socio-demographic risk factors. Results There were 58 malaria infection episodes observed during the follow up period, including 47 first and 11 repeat infections. The incidence of malaria was 0.25 [95% CI (0.19, 0.32)] and of first malaria was 0.23 [95% CI (0.17, 0.30)] per person per 24 weeks (0.22 in 6–59-month-olds, 0.26 in 5–17-year-olds, 0.20 in 18–45-year-olds). Incidence of first malaria with symptoms was 0.13 [95% CI (0.09, 0.19)] per person per 24 weeks (0.16 in 6–59-month-olds, 0.10 in 5–17-year-olds, 0.11 in 18–45-year-olds). Multivariate assessment showed that study area, gender, malaria positivity at screening, and household socioeconomic status independently predicted the observed incidence of malaria. Conclusion Despite intensive malaria control efforts on Bioko Island, local transmission remains and is spread evenly throughout age groups. These incidence rates indicate moderate malaria transmission which may be sufficient to support future larger trials of PfSPZ Vaccine. The long-term goal is to conduct mass vaccination programmes to halt transmission and eliminate P. falciparum malaria.

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Use of Market Data to Assess Bushmeat Hunting Sustainability in Equatorial Guinea

Conservation Biology ◽

10.1111/j.1523-1739.2011.01681.x ◽

2011 ◽

Vol 25 (3) ◽

pp. 597-606 ◽

Cited By ~ 27

Author(s):

S.M. ALLEBONE-WEBB ◽

N.F. KÜMPEL ◽

J. RIST ◽

G. COWLISHAW ◽

J.M. ROWCLIFFE ◽

...

Keyword(s):

Equatorial Guinea ◽

Market Data ◽

Bushmeat Hunting

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The family Lecithoceridae (Lepidoptera, Gelechioidea) from Bioko Island (Equatorial Guinea), with descriptions of five new species

Zootaxa ◽

10.11646/zootaxa.4995.3.12 ◽

2021 ◽

Vol 4995 (3) ◽

pp. 581-593

Author(s):

KYU-TEK PARK ◽

TIMM KARISCH

Keyword(s):

New Species ◽

Equatorial Guinea ◽

Bioko Island ◽

The Family ◽

First Time ◽

A New Species

Five new species belonging to the subfamily Torodorinae of Lecithoceridae are described from Bioko Island (Equatorial Guinea), based on specimens which were collected during a short expedition on the island by the second author in 1994. The new species are three species of the genus Thubdora Park, 2018 (T. biocoica sp. nov., T. vernaculella sp. nov., and T. angustiala sp. nov.), and a new species of Ptilothyris Walsingham, 1891and Dragmatucha Meyrick, 1908 respectively (Ptylothyris ruicheensis sp. nov.; and Dragmatucha vulcaniella sp. nov.). In addition, Thubdora bilobella Park, 2018 is reported for the first time from Equatorial Guinea. Images for adults and the genitalia of all species are given.

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Genetic diversity and allele frequencies of Plasmodium falciparum msp1 and msp2 in parasite isolates from Bioko Island, Equatorial Guinea

Malaria Journal ◽

10.1186/s12936-018-2611-z ◽

2018 ◽

Vol 17 (1) ◽

Cited By ~ 6

Author(s):

Jiang-Tao Chen ◽

Jian Li ◽

Guang-Cai Zha ◽

Guang Huang ◽

Zhi-Xiu Huang ◽

...

Keyword(s):

Genetic Diversity ◽

Plasmodium Falciparum ◽

Allele Frequencies ◽

Equatorial Guinea ◽

Bioko Island

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The Effects of Nest Location and Beach Environment on Hatching Success for Leatherback (Dermochelys Coriacea) and Green (Chelonia Mydas) Sea Turtles on Bioko Island, Equatorial Guinea

10.21203/rs.3.rs-317848/v1 ◽

2021 ◽

Author(s):

Callie A. Veelenturf ◽

Elizabeth M. Sinclair ◽

Peter Leopold ◽

Frank V. Paladino ◽

Shaya Honarvar

Keyword(s):

Green Turtle ◽

Hatching Success ◽

Sea Turtles ◽

Chelonia Mydas ◽

Dermochelys Coriacea ◽

Equatorial Guinea ◽

Leatherback Turtles ◽

Nest Location ◽

Bioko Island ◽

Elevation Range

Abstract Hatching success in sea turtles is hindered by a variety of biotic and abiotic factors. This study of the nesting ecology of leatherback (Dermochelys coriacea) and green (Chelonia mydas) sea turtles, investigated how several environmental factors and beach characteristics on Bioko Island, Equatorial Guinea influence sea turtle reproductive success. Average clutch hatching success was 40.4% for green turtles and 41.73% for leatherback turtles. For leatherback turtles, clutch elevation relative to the high tide line (HTL) was found to be the most influential factor in determining hatching success, highlighting the sensitivity of this species to sea level rise (SLR). Multiple linear regression analysis demonstrated that nest distance to vegetation and sand conductivity also played significant roles in leatherback clutch hatching success. For leatherback clutches, 33% percent of experimental nests were affected by inundation and 17% by predation. An optimum clutch elevation range for leatherback turtles was identified, where a distinct increase in hatching success was observed between -0.286 m to -0.0528 m above the HTL. For green sea turtles, 64% of experimental nests were affected by predation, confounding conclusions about the roles of environmental characteristics in green turtle hatching success. We propose further investigation into influential characteristics in green turtle nests and confirmation of the observed optimum elevation range on Bioko Island and other nesting grounds. Identified sensitivities of each species to SLR and beach characteristics will be used to encourage the government of Equatorial Guinea to consider the vulnerability of their resident turtle populations when planning for future coastal development.

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