American Cutaneous Leishmaniasis in Panama: a historical review of entomological studies on anthropophilic Lutzomyia sand fly species

We review existing information on the epidemiology of American Cutaneous Leishmaniasis (ACL) in Panama, with emphasis on the bionomics of anthropophilic Lutzomyia sand fly species. Evidence from Panamanian studies suggests that there are six anthropophilic species in the country: Lutzomyia trapidoi, Lu. panamensis, Lu. gomezi, Lu. ylephiletor, Lu. sanguinaria and Lu. pessoana (Henceforth Lu. carrerai thula). In general, these taxa are abundant, widespread and feed opportunistically on their hosts, which make them potential transmitters of pathogens to a broad range of wildlife, domesticated animals and humans. Furthermore, nearly all man-biting species in Panama (with the exception of Lu. gomezi) expand demographically during the rainy season when transmission is likely higher due to elevated Leishmania infection rates in vector populations. Despite this, data on the distribution and prevalence of ACL suggest little influence of vector density on transmission intensity. Apart from Lu. trapidoi, anthropophilic species seem to be most active in the understory, but vertical stratification, as well as their opportunistic feeding behavior, could vary geographically. This in turn seems related to variation in host species composition and relative abundance across sites that have experienced different degrees of human alteration (e.g., deforestation) in leishmaniasis endemic regions of Panama.We review existing information on the epidemiology of American Cutaneous Leishmaniasis (ACL) in Panama, with emphasis on the bionomics of anthropophilic Lutzomyia sand fly species. Evidence from Panamanian studies suggests that there are six anthropophilic species in the country: Lutzomyia trapidoi, Lu. panamensis, Lu. gomezi, Lu. ylephiletor, Lu. sanguinaria and Lu. pessoana (Henceforth Lu. carrerai thula). In general, these taxa are abundant, widespread and feed opportunistically on their hosts, which make them potential transmitters of pathogens to a broad range of wildlife, domesticated animals and humans. Furthermore, nearly all man-biting species in Panama (with the exception of Lu. gomezi) expand demographically during the rainy season when transmission is likely higher due to elevated Leishmania infection rates in vector populations. Despite this, data on the distribution and prevalence of ACL suggest little influence of vector density on transmission intensity. Apart from Lu. trapidoi, anthropophilic species seem to be most active in the understory, but vertical stratification, as well as their opportunistic feeding behavior, could vary geographically. This in turn seems related to variation in host species composition and relative abundance across sites that have experienced different degrees of human alteration (e.g., deforestation) in leishmaniasis endemic regions of Panama

Cambios en la estructura comunitaria y taxonomia molecular de mosquitos vectores de enfermedades (díptera: Culicidae) en areas deforestadas y boscosas de Panamá

En este estudio se colectaron y criaron estados inmaduros de mosquitos; y se utilizó la técnica de códigos de barra de ADN para investigar la taxonomía de especies de Culicidae poco estudiadas en Panamá. Se usaron las secuencias del gen CO] para investigar los cambios en la riqueza de linajes moleculares entre una localidad poco intervenida y dos muy alteradas por actividades humanas. Se colectó y crió 1,185 mosquitos en total, de los cuales se extrajo el ADN genómico de 712 individuos y se utilizaron 380 haplotipos en los análisis filogenéticos. Los árboles de distancias genéticas delimitaron un total de 52 linajes moleculares o "Cluster", la gran mayoría con valores de Boostrap superiores al 95 por ciento. La delimitación de los linajes moleculares concordó con la identificación morfológica inicial de las muestras secuenciadas, sin embargo, hubo excepciones, por ejemplo, las especies Mansonia titillans, Mansonia indubitans y Mansonia dyari se agruparon en un solo Cluster en vez de en tres distintos. Además, los individuos identificados morfológicamente como Uranotaenia lowi se agruparon en tres linajes moleculares distintos que presentaron divergencias genéticas superiores al 2 por ciento. Por otro lado, BCI presentó el mayor número de linajes moleculares únicos conó14 seguido por Las Pavas y Achiote con 7 y 6 cada uno, respectivamente. Las Pavas y Achiote compartieron el mayor numero de linajes moleculares entre si con 8 en total, mientras que Las Pavas y BCI compartieron 5, seguido por Achiote y BCI con 2. Nuestros resultados indican que los cambios en la estructura comunitaria de los mosquitos no se deben a la distancia geográfica y/o variabilidad climática entre localidades, lino a los diferentes grados de perturbación humana que estas presentan. Las diferencias entre BCI, Las Pavas y Achiote parecen estar determinadas por la calidad y cantidad de habitats larvales para mosquitos, BCI posee mayor proporción y variedad de sitios de cría para especies de mosquitos especialistas del bosque, mientras que estos sitios de cría disminuyen por causa de la deforestación en Las Pavas y Achiote. La relevancia epidemiológica de estos resultados radica en que en ocasiones las especies generalistas como Anopheles albimanus, Aedes angustivittattus, Psorophora cingulata, Culex coronator y Culex interrogator son vectores mas eficientes en la transmisión de patógenos a humanos, ya que se adaptan a vivir en el peri-domicilio, se alimentan preferencialmente de sangre humana y sus poblaciones crecen exponencialmente

Diverse novel phleboviruses in sandflies from the Panama Canal area, Central Panama

The genus Phlebovirus (order Bunyavirales, family Phenuiviridae) comprises 57 viruses that are grouped into nine speciescomplexes. Sandfly-transmitted phleboviruses are found in Europe, Africa and the Americas and are responsible for febrile illness and infections of the nervous system in humans. The aim of this study was to assess the genetic diversity of sandflytransmitted phleboviruses in connected and isolated forest habitats throughout the Panama Canal area in Central Panama. In total, we collected 13 807 sandflies comprising eight phlebotomine species. We detected several strains pertaining to five previously unknown viruses showing maximum pairwise identities of 45–78 % to the RNA-dependent RNA polymerase genes of phleboviruses. Entire coding regions were directly sequenced from infected sandflies as virus isolation in cell culture was not successful. The viruses were tentatively named La Gloria virus (LAGV), Mona Grita virus (MOGV), Peña Blanca virus (PEBV), Tico virus (TICV) and Tres Almendras virus (TRAV). Inferred phylogenies and p-distance-based analyses revealed that PEBV groups with the Bujaru phlebovirus species-complex, TRAV with the Candiru phlebovirus speciescomplex and MOGV belongs to the proposed Icoarci phlebovirus species-complex, whereas LAGV and TICV seem to be distant members of the Bujaru phlebovirus species-complex. No specific vector or habitat association was found for any of the five viruses. Relative abundance of sandflies was similar over habitat types. Our study shows that blood-feeding insects originating from remote and biodiverse habitats harbour multiple previously unknown phleboviruses. These viruses should be included in future surveillance studies to assess their geographic distribution and to elucidate if these viruses cause symptoms of disease in animals or humans.The genus Phlebovirus (order Bunyavirales, family Phenuiviridae) comprises 57 viruses that are grouped into nine speciescomplexes. Sandfly-transmitted phleboviruses are found in Europe, Africa and the Americas and are responsible for febrile illness and infections of the nervous system in humans. The aim of this study was to assess the genetic diversity of sandflytransmitted phleboviruses in connected and isolated forest habitats throughout the Panama Canal area in Central Panama. In total, we collected 13 807 sandflies comprising eight phlebotomine species. We detected several strains pertaining to five previously unknown viruses showing maximum pairwise identities of 45–78 % to the RNA-dependent RNA polymerase genes of phleboviruses. Entire coding regions were directly sequenced from infected sandflies as virus isolation in cell culture was not successful. The viruses were tentatively named La Gloria virus (LAGV), Mona Grita virus (MOGV), Peña Blanca virus (PEBV), Tico virus (TICV) and Tres Almendras virus (TRAV). Inferred phylogenies and p-distance-based analyses revealed that PEBV groups with the Bujaru phlebovirus species-complex, TRAV with the Candiru phlebovirus speciescomplex and MOGV belongs to the proposed Icoarci phlebovirus species-complex, whereas LAGV and TICV seem to be distant members of the Bujaru phlebovirus species-complex. No specific vector or habitat association was found for any of the five viruses. Relative abundance of sandflies was similar over habitat types. Our study shows that blood-feeding insects originating from remote and biodiverse habitats harbour multiple previously unknown phleboviruses. These viruses should be included in future surveillance studies to assess their geographic distribution and to elucidate if these viruses cause symptoms of disease in animals or humans

Forest disturbance and vector transmitted diseases in thelowland tropical rainforest of central Panama

objective To explore possible changes in the community attributes of haematophagous insects as afunction of forest disturbance. We compare the patterns of diversity and abundance, plus thebehavioural responses of three epidemiologically distinct vector assemblages across sites depictingvarious levels of forest cover.methods Over a 3-year period, we sampled mosquitoes, sandflies and biting-midges in forestedhabitats of central Panama. We placed CDC light traps in the forest canopy and in the understorey togather blood-seeking females.results We collected 168 405 adult haematophagous dipterans in total, including 26 genera and 86species. Pristine forest settings were always more taxonomically diverse than the disturbed forest sites,confirming that disturbance has a negative impact on species richness. Species of Phlebotominae andCulicoides were mainly classified as climax (i.e. forest specialist) or disturbance-generalist, which tendto decrease in abundance along with rising levels of disturbance. In contrast, a significant portion ofmosquito species, including primary and secondary disease vectors, was classified as colonists (i.e.disturbed-areas specialists), which tend to increase in numbers towards more disturbed forest habitats.At pristine forest, the most prevalent species of Phlebotominae and Culicoides partitioned the verticalniche by being active at the forest canopy or in the understorey; yet this pattern was less clear indisturbed habitats. Most mosquito species were not vertically stratified in their habitat preference.conclusion We posit that entomological risk and related pathogen exposure to humans is higher inpristine forest scenarios for Culicoides and Phlebotominae transmitted diseases, whereas forestdisturbance poses a higher entomological risk for mosquito-borne infections. This suggests that theDilution Effect Hypothesis (DEH) does not apply in tropical rainforests where highly abundant, yetunrecognised insect vectors and neglected zoonotic diseases occur. Comprehensive, community levelentomological surveillance is, therefore, the key for predicting potential disease spill over in scenariosof pristine forest intermixed with anthropogenic habitats. We suggest that changes in forest qualityshould also be considered when assessing arthropod-borne disease transmission risk.objective To explore possible changes in the community attributes of haematophagous insects as afunction of forest disturbance. We compare the patterns of diversity and abundance, plus thebehavioural responses of three epidemiologically distinct vector assemblages across sites depictingvarious levels of forest cover.methods Over a 3-year period, we sampled mosquitoes, sandflies and biting-midges in forestedhabitats of central Panama. We placed CDC light traps in the forest canopy and in the understorey togather blood-seeking females.results We collected 168 405 adult haematophagous dipterans in total, including 26 genera and 86species. Pristine forest settings were always more taxonomically diverse than the disturbed forest sites,confirming that disturbance has a negative impact on species richness. Species of Phlebotominae andCulicoides were mainly classified as climax (i.e. forest specialist) or disturbance-generalist, which tendto decrease in abundance along with rising levels of disturbance. In contrast, a significant portion ofmosquito species, including primary and secondary disease vectors, was classified as colonists (i.e.disturbed-areas specialists), which tend to increase in numbers towards more disturbed forest habitats.At pristine forest, the most prevalent species of Phlebotominae and Culicoides partitioned the verticalniche by being active at the forest canopy or in the understorey; yet this pattern was less clear indisturbed habitats. Most mosquito species were not vertically stratified in their habitat preference.conclusion We posit that entomological risk and related pathogen exposure to humans is higher inpristine forest scenarios for Culicoides and Phlebotominae transmitted diseases, whereas forestdisturbance poses a higher entomological risk for mosquito-borne infections. This suggests that theDilution Effect Hypothesis (DEH) does not apply in tropical rainforests where highly abundant, yetunrecognised insect vectors and neglected zoonotic diseases occur. Comprehensive, community levelentomological surveillance is, therefore, the key for predicting potential disease spill over in scenariosof pristine forest intermixed with anthropogenic habitats. We suggest that changes in forest qualityshould also be considered when assessing arthropod-borne disease transmission risk

Epidemic and Non-Epidemic Hot Spots of Malaria Transmission Occur in Indigenous <i>Comarcas</i> of Panama

<div><p>From 2002–2005, Panama experienced a malaria epidemic that has been associated with El Niño Southern Oscillation weather patterns, decreased funding for malaria control, and landscape modification. Case numbers quickly decreased afterward, and Panama is now in the pre-elimination stage of malaria eradication. To achieve this new goal, the characterization of epidemiological risk factors, foci of transmission, and important anopheline vectors is needed. Of the 24,681 reported cases in these analyses (2000–2014), ~62% occurred in epidemic years and ~44% in indigenous <i>comarcas</i> (5.9% of Panama’s population). Sub-analyses comparing overall numbers of cases in epidemic and non-epidemic years identified females, <i>comarcas</i> and some 5-year age categories as those disproportionately affected by malaria during epidemic years. Annual parasites indices (APIs; number of cases per 1,000 persons) for <i>Plasmodium vivax</i> were higher in <i>comarcas</i> compared to provinces for all study years, though <i>P</i>. <i>falciparum</i> APIs were only higher in <i>comarcas</i> during epidemic years. Interestingly, two <i>comarcas</i> report increasing numbers of cases annually, despite national annual decreases. Inclusion of these <i>comarcas</i> within identified foci of malaria transmission confirmed their roles in continued transmission. Comparison of species distribution models for two important anophelines with <i>Plasmodium</i> case distribution suggest <i>An</i>. <i>albimanus</i> is the primary malaria vector in Panama, confirmed by identification of nine <i>P</i>. <i>vivax</i>-infected specimen pools. Future malaria eradication strategies in Panama should focus on indigenous <i>comarcas</i> and include both active surveillance for cases and comprehensive anopheline vector surveys.</p></div

Number of districts and <i>corregimientos</i> (centroids) per province or <i>comarca</i> in Panama.

<p>Number of districts and <i>corregimientos</i> (centroids) per province or <i>comarca</i> in Panama.</p

Comparison of predicted <i>Anopheles albimanus</i> and <i>An</i>. <i>punctimacula s</i>.<i>l</i>. distributions together with the distributions of <i>Plasmodium vivax</i> and <i>P</i>. <i>falciparum</i> cases in Panama.

<p>Comparison of predicted <i>Anopheles albimanus</i> and <i>An</i>. <i>punctimacula s</i>.<i>l</i>. distributions together with the distributions of <i>Plasmodium vivax</i> and <i>P</i>. <i>falciparum</i> cases in Panama.</p

Species distribution models.

<p><b>A</b> and <b>C</b>) <i>Anopheles albimanus</i> and <b>B</b> and <b>D</b>) <i>Anopheles punctimacula s</i>.<i>l</i>. in Panama. Panels <b>A</b> and <b>B</b> represent the full extent of the species distribution models. Panels <b>C</b> and <b>D</b> represent the distributions of each species within Panama. Color shading indicates areas of predicted suitable habitat/presence of the species; white indicates areas of predicted absence of the species. Central and South American GIS shapefiles freely available from DIVA-GIS [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004718#pntd.0004718.ref074" target="_blank">74</a>]. Panama GIS shapefile obtained from STRI [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004718#pntd.0004718.ref030" target="_blank">30</a>].</p

Total frequency of cluster occurrence for <i>Plasmodium vivax</i> and <i>P</i>. <i>falciparum</i> in Panama.

<p><i>Corregimientos</i> are colored by the frequency at which they were identified by both hot spot detection methods over the designated period. <b>A</b>) <i>P</i>. <i>vivax</i> cluster frequency by <i>corregimiento</i> in epidemic years (2002–2005; maximum frequency = 8). <b>B</b>) <i>P</i>. <i>falciparum</i> cluster frequency by <i>corregimiento</i> in epidemic years (2002–2005; maximum frequency = 8). <b>C</b>) <i>P</i>. <i>vivax</i> cluster frequency by <i>corregimiento</i> in non-epidemic years (2000–2001, 2006–2014; maximum frequency = 22). <b>D</b>) <i>P</i>. <i>falciparum</i> cluster frequency by <i>corregimiento</i> in non-epidemic years (2000–2001, 2006–2010; maximum frequency = 14). Frequencies were calculated using data shown in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004718#pntd.0004718.s002" target="_blank">S1</a> and <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004718#pntd.0004718.s003" target="_blank">S2</a> Figs. Panama GIS shapefile obtained from STRI [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004718#pntd.0004718.ref030" target="_blank">30</a>].</p