Malaria risk stratification in Colombia 2010 to 2019

Exploring the Diversity of Microbial Communities Associated with Two Anopheles Species During Dry Season in an Indigenous Community from the Colombian Amazon

Malaria disease affects millions of people annually, making the Amazon Basin a major hotspot in the Americas. While traditional control strategies rely on physical and chemical methods, the Anopheles microbiome offers a promising avenue for biological control, as certain bacteria can inhibit parasite development and alter vector immune and reproductive systems, disrupting the transmission cycle. For this reason, this study aimed to explore the bacterial communities in An. darlingi and An. triannulatus s.l., including breeding sites, immature stages, and adults from San Pedro de los Lagos (Leticia, Amazonas) through next-generation sequencing of the 16S rRNA gene. The results revealed a higher bacterial genus richness in the L1-L2 larvae of An. triannulatus s.l. Aeromonas and Enterobacter were prevalent in most samples, with abundances of 52.51% in L3-L4 larvae and 48.88% in pupae of An. triannulatus s.l., respectively. In breeding site water, Verrucomicrobiota bacteria were the most dominant (52.39%). We also identified Delftia (15.46%) in An. triannulatus s.l. pupae and Asaia (98.22%) in An. triannulatus, linked to Plasmodium inhibition, and Elizabethkingia, in low abundances, along with Klebsiella and Serratia, known for paratransgenesis potential. Considering the high bacterial diversity observed across the different mosquito life stages, identifying bacterial composition is the first step towards developing new strategies for malaria control. However, the specific roles of these bacteria in anophelines and the malaria transmission cycle remain to be elucidated.

Malaria, Dengue Fever, and Leptospirosis in the Urabá Antioqueño Region, Colombia: Etiological and Molecular Characterization among Patients with Acute Undifferentiated Febrile Illness

Acute undifferentiated febrile illness (AUFI) is the main cause of medical attention in the tropics worldwide. Malaria, arboviral diseases, and leptospirosis are the most important etiologies. These are highly endemic in the Urabá antioqueño, Colombia, being the main causes of fever in several municipalities in this region. However, up-to-date data regarding the infecting species and serotypes are lacking. Thus, we characterized the etiology of AUFI, focusing on malaria, arboviruses, and leptospirosis in this region and the circulating infecting species. An active surveillance was conducted between January and April 2022, and July and October 2023 in two local hospitals in the Urabá antioqueño. Febrile patients were enrolled voluntarily. Malaria, arboviral diseases, and leptospirosis were screened through direct, serological, molecular, and rapid diagnostic methods. Amplicons obtained for dengue virus (DENV) and Leptospira spp. were analyzed through phylogenetic analysis. A total of 184 febrile patients were enrolled. A confirmed etiology was detected in 43.4% of patients from Apartadó and 61.2% from Turbo. Malaria was the most frequent cause in both municipalities, which was caused mainly by Plasmodium falciparum in Apartadó and Plasmodium vivax in Turbo. Dengue virus serotype 1 genotype V, DENV genotype Asian-American, and DENV genotype Cosmopolitan were identified, as well as pathogenic Leptospira species closely related to Leptospira santarosai and Leptospira noguchii. The present study confirms the importance of malaria, dengue fever, and leptospirosis in the Urabá antioqueño. Plasmodium falciparum and P. vivax were identified, as well as two DENV serotypes and three DENV genotypes and two different Leptospira species.

Community Knowledge, Attitudes and Practices About Malaria: Insights from a Northwestern Colombian Endemic Locality

Malaria prevention and control programs are mainly oriented to vector control, timely diagnosis and adequate treatment. Malaria transmission is influenced by several factors, including biological and social aspects. Thus, it is relevant to consider community beliefs and practices to ensure sustainable prevention and control strategies. This study aimed to determine knowledge, attitudes and practices (KAP) towards malaria in an endemic locality in northwestern Colombia. Preliminary data were collected through a focus group discussion. Subsequently, a KAP survey was administered to the community. KAP scores were associated with both sociodemographic characteristics and with previous malaria infection. Focus group data revealed knowledge gaps and the absence of or having worn-out nets. Survey results showed that participants recognized a mosquito bite as the transmission mode (72.09%), followed by dirty water (44.19%), high fever (86.05%) and headache (79.07%) as the main symptoms. Regarding attitudes, 44.19% of the people would go to the hospital in the case of having symptoms. The most recognized practices for disease prevention were the use of mosquito nets (65.12%) and fans (23.26%). The results showed that some people had misconceptions about the disease transmission mode. The analysis showed significant associations of either female gender and homemaker occupation with a good knowledge [OR = 3.74, (p = 0.04), OR = 3.55, (p = 0.04), respectively] or female with a positive attitude towards malaria control and prevention [OR = 4.80, (p = 0.04)]. These results showed that the identified gaps in KAP require increasing education among the community in addition to applying public health prevention efforts. The data may be useful in designing malaria control strategies that involve community participation.

Malaria Vectors and Plasmodium Transmission in Malaria-Endemic Localities of Colombia

Anopheles species composition, abundance, and Plasmodium natural infection are important aspects to assess malaria transmission risk. In this study, these aspects were evaluated in a large number of localities in the most important malaria-endemic regions of Colombia. Mosquitoes were collected from 2012 to 2015 in 55 localities of northwestern and western Colombia. Anopheles species composition, abundance, and Plasmodium infection were estimated. A total of 13,218 Anopheles specimens were evaluated. The highest species richness was detected in the northwest, where the main vectors, An. albimanus (27.8%) and An. nuneztovari (26.7%), were the most abundant species. In the west, An. nuneztovari predominated (51.6%), followed by An. darlingi (29.2%). Six species were infected with Plasmodium, An. darlingi, An. nuneztovari, An. albimanus, An. calderoni, An. triannulatus, and An. braziliensis. Results showed that in these localities the main Colombian vectors are widely spread, which suggests a high malaria risk. Notably, this study is the first to report An. braziliensis from Colombia as being naturally infected with Plasmodium. Infection results for species that are suspected local vectors indicate the importance of conducting further studies to assess their epidemiological importance. This information provides the basis for the application of directed vector control strategies that are species-specific.

First report of an acute case of chagas disease in the municipality of Miraflores, Guaviare, Colombia

We present a case of acute phase Chagas disease in a 40-year-old male patient from Vereda Buenos Aires, Municipality of Miraflores, Department of Guaviare. The patient attended the emergency department with fever, headache, asthenia, adynamia and dysuria. The blood smear and urinalysis were positive for symptomatic urinary tract infection, but negative for malaria. Five days later the diagnosis of acute phase Chagas disease was confirmed after a positive result for Trypanosoma cruzi. The patient was treated with nifurtimox and benznidazole, his contacts and risk areas were investigated, an active entomological community and institutional search was carried out, as well as in the reservoirs, finally, laboratory surveillance for possible cases of infection in the community was conducted. Five cases with similar symptoms were identified, but parasitological tests were negative. Health education measures were implemented to prevent the spread of the disease.

Changes in the endemic-epidemic pattern of malaria in Colombia, 1978-2021

BACKGROUND

Malaria is a major global public health issue with varying epidemiologies across countries. In Colombia, it is a priority endemic-epidemic event included in the national public health policy. However, evidence demonstrating nationwide variations in the disease behavior is limited. This study aimed to analyze changes in the levels and distribution of endemic-epidemic malaria transmission in the eco-epidemiological regions of Colombia from 1978 to 1999 and 2000 to 2021.

METHODS

We conducted a comprehensive time-series study using official secondary data on malaria-associated morbidity and mortality in Colombia from 1978 to 2021. Temporal-spatial and population variables were analyzed, and the absolute and relative frequency measures of general and regional morbidity and mortality were estimated.

RESULTS

We observed an 18% reduction in malaria endemic cases between the two study periods. The frequency and severity of the epidemic transmission of malaria varied less and were comparable across both periods. A shift was observed in the frequency of parasitic infections, with a tendency to match and increase infections by Plasmodium falciparum. The risk of malaria transmission varied significantly among the eco-epidemiological regions during both study periods. This study demonstrated a sustained decrease of 78% in malarial mortality.

CONCLUSIONS

Although the endemic components of malaria decreased slightly between the two study periods, the epidemic pattern persisted. There were significant variations in the risk of transmission across the different eco-epidemiological regions. These findings underscore the importance of targeted public health interventions in reducing malarial morbidity and mortality rates in Colombia.

Evaluating the genetic diversity of the Plasmodium vivax siap2 locus: A promising candidate for an effective malaria vaccine?

Malaria is the deadliest parasitic disease in the world. Traditional control measures have become less effective; hence, there is a need to explore alternative strategies, such as antimalarial vaccines. However, designing an anti-Plasmodium vivax vaccine is considered a challenge due to the complex parasite biology and the antigens' high genetic diversity. Recently, the sporozoite invasion-associated protein 2 (SIAP2) has been suggested as a potential antigen to be considered in vaccine design due to its significance during hepatocyte invasion. However, its use may be limited by the incomplete understanding of gene/protein diversity. Here, the genetic diversity of pvsiap2 using P. vivax DNA samples from Colombia was assessed. Through PCR amplification and sequencing, we compared the Colombian sequences with available worldwide sequences, revealing that pvsiap2 displays low genetic diversity. Molecular evolutionary analyses showed that pvsiap2 appears to be influenced by directional selection. Moreover, the haplotypes found differ by a few mutational steps and several of them were shared between different geographical areas. On the other hand, several conserved regions within PvSIAP2 were predicted as potential B-cell or T-cell epitopes. Considering these characteristics and its role in hepatocyte invasion, the PvSIAP2 protein emerges as a promising antigen to be considered in a multi-antigen-multi-stage (multivalent) fully effective vaccine against P. vivax malaria.

Malaria risk stratification in Lao PDR guides program planning in an elimination setting

Malaria in Lao People's Democratic Republic (Lao PDR) has declined rapidly over the last two decades, from 279,903 to 3926 (99%) cases between 2001 and 2021. Elimination of human malaria is an achievable goal and limited resources need to be targeted at remaining hotspots of transmission. In 2022, the Center of Malariology, Parasitology and Entomology (CMPE) conducted an epidemiological stratification exercise to assign districts and health facility catchment areas (HFCAs) in Lao PDR based on malaria risk. The stratification used reported malaria case numbers from 2019 to 2021, risk maps derived from predictive modelling, and feedback from malaria staff nationwide. Of 148 districts, 14 were deemed as burden reduction (high risk) districts and the remaining 134 as elimination (low risk) districts. Out of 1235 HFCAs, 88 (7%) were classified as highest risk, an improvement from 187 (15%) in the last stratification in 2019. Using the HFCA-level stratification, the updated stratification resulted in the at-risk population (total population in Strata 2, 3 and 4 HFCAs) declining from 3,210,191 to 2,366,068, a 26% decrease. CMPE are using the stratification results to strengthen targeting of resources. Updating national stratifications is a necessary exercise to assess progress in malaria control, reassign interventions to the highest risk populations in the country and ensure greatest impact of limited resources.

Malaria Stratification Mapping in Thailand to Support Prevention of Reestablishment

Thailand aims to eliminate malaria by 2026, with 46 of the country's 77 provinces already verified as malaria free. However, these provinces remain susceptible to the reestablishment of indigenous transmission that would threaten the national goal. Thus, the country is prioritizing national and subnational prevention of reestablishment (POR) planning while considering the spatial heterogeneity of the remaining malaria caseload. To support POR efforts, a novel nonmodeling method produced a malaria stratification map at the tambon (subdistrict) level, incorporating malaria case data, demographic data, and environmental factors. The stratification analysis categorized 7,425 tambons into the following four risk strata: Local Transmission (2.9%), At Risk for Transmission (3.1%), High Risk for Reintroduction (2.9%), and Low Risk for Reintroduction (91.1%). The stratification map will support the national program to target malaria interventions in remaining hotspots and mitigate the risk of transmission in malaria-free areas.

Etiological characterization of acute undifferentiated febrile illness in Apartadó and Villeta municipalities, Colombia, during COVID-19 pandemic

Background

Acute undifferentiated febrile illness (AUFI) is one of the leading causes of illness in tropical regions. Although malaria is the most important cause, other pathogens such as Dengue (DENV), Leptospira and recently, Coronavirus Disease 2019 (COVID-19) have gained importance. In Colombia, few studies aimed to identify the etiology of AUFI. Most of them performed in Apartadó and Villeta municipalities, identifying the active circulation of several pathogens. Thus, we conducted a cross-sectional study in these municipalities to characterize the etiologies of AUFI during COVID-19 pandemic.

Methods

An active surveillance was conducted between September and December 2021 in local hospitals of Apartadó and Villeta municipalities. Febrile patients were enrolled after voluntarily agreeing to participate in the study. Ten different etiologies were evaluated through direct, serological, molecular and rapid diagnostic methods.

Results

In Apartadó a confirmed etiology was found in 60% of subjects, DENV (25%) being the most frequent, followed by leptospirosis (16.7%), malaria (10%), COVID-19 (8.3%), spotted fever group (SFG) rickettsiosis (6.7%) and Chikungunya (1.7%). In Villeta, a specific etiology was confirmed in 55.4% of patients, of which SFG rickettsiosis (39.3%) was the most frequent, followed by leptospirosis (21.4%), DENV (3.6%) and malaria (1.8%). No cases due to Mayaro, Yellow Fever, Oropouche and Venezuelan Equine Encephalitis viruses were detected.

Conclusion

We confirm the relevance of dengue fever, leptospirosis, SFG rickettsiosis, COVID-19 and malaria as causes of AUFI in the municipality of Apartadó, and highlight the great importance of SFG rickettsiosis as the main cause of AUFI in the municipality of Villeta.

Time lag effect on malaria transmission dynamics in an Amazonian Colombian municipality and importance for early warning systems

Malaria remains a significant public health problem worldwide, particularly in low-income regions with limited access to healthcare. Despite the use of antimalarial drugs, transmission remains an issue in Colombia, especially among indigenous populations in remote areas. In this study, we used an SIR Ross MacDonald model that considered land use change, temperature, and precipitation to analyze eco epidemiological parameters and the impact of time lags on malaria transmission in La Pedrera-Amazonas municipality. We found changes in land use between 2007 and 2020, with increases in forested areas, urban infrastructure and water edges resulting in a constant increase in mosquito carrying capacity. Temperature and precipitation variables exhibited a fluctuating pattern that corresponded to rainy and dry seasons, respectively and a marked influence of the El Niño climatic phenomenon. Our findings suggest that elevated precipitation and temperature increase malaria infection risk in the following 2 months. The risk is influenced by the secondary vegetation and urban infrastructure near primary forest formation or water body edges. These results may help public health officials and policymakers develop effective malaria control strategies by monitoring precipitation, temperature, and land use variables to flag high-risk areas and critical periods, considering the time lag effect.

A conserved epitope in VAR2CSA is targeted by a cross-reactive antibody originating from Plasmodium vivax Duffy binding protein

During Plasmodium falciparum infection in pregnancy, VAR2CSA is expressed on the surface of infected erythrocytes (IEs) and mediates their sequestration in the placenta. As a result, antibodies to VAR2CSA are largely restricted to women who were infected during pregnancy. However, we discovered that VAR2CSA antibodies can also be elicited by P. vivax Duffy binding protein (PvDBP). We proposed that infection with P. vivax in non-pregnant individuals can generate antibodies that cross-react with VAR2CSA. To better understand the specificity of these antibodies, we took advantage of a mouse monoclonal antibody (3D10) raised against PvDBP that cross-reacts with VAR2CSA and identified the epitopes targeted by this antibody. We screened two peptide arrays that span the ectodomain of VAR2CSA from the FCR3 and NF54 alleles. Based on the top epitope recognized by 3D10, we designed a 34-amino acid synthetic peptide, which we call CRP1, that maps to a highly conserved region in DBL3X. Specific lysine residues are critical for 3D10 recognition, and these same amino acids are within a previously defined chondroitin sulfate A (CSA) binding site in DBL3X. We showed by isothermal titration calorimetry that the CRP1 peptide can bind directly to CSA, and antibodies to CRP1 raised in rats significantly blocked the binding of IEs to CSA in vitro. In our Colombian cohorts of pregnant and non-pregnant individuals, at least 45% were seroreactive to CRP1. Antibody reactivities to CRP1 and the 3D10 natural epitope in PvDBP region II, subdomain 1 (SD1), were strongly correlated in both cohorts. These findings suggest that antibodies arising from PvDBP may cross-react with VAR2CSA through the epitope in CRP1 and that CRP1 could be a potential vaccine candidate to target a distinct CSA binding site in VAR2CSA.

Service availability and readiness of malaria surveillance information systems implementation at primary health centers in Indonesia

One of the most important indicators in malaria eradication is the malaria surveillance information system (SISMAL) for recording and reporting medical cases. This paper aims to describe the availability and readiness of SISMALs at primary health centers (PHCs) in Indonesia. A cross-sectional survey was implemented in seven provinces for this study. The data was analyzed using bivariate, multivariate, and linear regression. The availability of the information system was measured by assessing the presence of the electronic malaria surveillance information system (E-SISMAL) at the studied PHCs. The readiness was measured by averaging each component of the assessment. From 400 PHC samples, only 58.5% had available SISMALs, and their level of readiness was only 50.2%. Three components had very low levels of readiness: (1) the availability of personnel (40.9%), (2) SISMAL integration and storage (50.2%), and (3) the availability of data sources and indicators (56.8%). Remote and border (DTPK) areas had a 4% better readiness score than non-DTPK areas. Endemic areas were 1.4% better than elimination areas, while regions with low financial capacity were 3.78% better than regions with high financial capacity, with moderate capacity (2.91%). The availability rate of the SISMAL at PHCs is only 58.5%. Many PHCs still do not have SISMALs. The readiness of the SISMAL at these PHCs is significantly related to DTPK/remote area, high endemicity status, and low financial capacity. This study found that the implementation of SISMAL is more accessible to malaria surveillance for the remote area and regions with low financial capacity. Therefore, this effort will well-fit to address barrier to malaria surveillance in developing countries.

Environmental and socio-economic determinants of the occurrence of malaria clusters in Colombia

This study identifies the environmental and socio-economic determinants of clusters of high malaria incidence in Colombia during the period of 2008-2019. The malaria cases were obtained from the National System of Surveillance in Public Health, with 798,897 cases reported in the 986 Colombian municipalities evaluated during the study period. Spatial autocorrelation of incidence was examined with global and local indices. Clusters were identified in the Amazon, Pacific, and Uraba-Bajo Cauca-Alto Sinú regions. The factors associated with a municipality belonging to a high-incidence cluster were identified using a logistic regression model with mixed effects and showed a positive association for the variables (forest coverage and minimum multi-year average rainfall). An inverse relationship was observed for aqueduct coverage and the odds of belonging to a cluster. A 1% increase in forest coverage was associated with a 4.2% increase in the odds of belonging to a malaria cluster. The association with minimum multi-year average rainfall was positive (OR = 1.0011; 95% CI 1.0005-1.0027). A 1% increase in aqueduct coverage was associated with a 4.3% decrease in the odds of belonging to malaria cluster. The identification of malaria cluster determinants in Colombia could help guide surveillance and disease control policies.

Resolving drug selection and migration in an inbred South American Plasmodium falciparum population with identity-by-descent analysis

The human malaria parasite Plasmodium falciparum is globally widespread, but its prevalence varies significantly between and even within countries. Most population genetic studies in P. falciparum focus on regions of high transmission where parasite populations are large and genetically diverse, such as sub-Saharan Africa. Understanding population dynamics in low transmission settings, however, is of particular importance as these are often where drug resistance first evolves. Here, we use the Pacific Coast of Colombia and Ecuador as a model for understanding the population structure and evolution of Plasmodium parasites in small populations harboring less genetic diversity. The combination of low transmission and a high proportion of monoclonal infections means there are few outcrossing events and clonal lineages persist for long periods of time. Yet despite this, the population is evolutionarily labile and has successfully adapted to changes in drug regime. Using newly sequenced whole genomes, we measure relatedness between 166 parasites, calculated as identity by descent (IBD), and find 17 distinct but highly related clonal lineages, six of which have persisted in the region for at least a decade. This inbred population structure is captured in more detail with IBD than with other common population structure analyses like PCA, ADMIXTURE, and distance-based trees. We additionally use patterns of intra-chromosomal IBD and an analysis of haplotypic variation to explore past selection events in the region. Two genes associated with chloroquine resistance, crt and aat1, show evidence of hard selective sweeps, while selection appears soft and/or incomplete at three other key resistance loci (dhps, mdr1, and dhfr). Overall, this work highlights the strength of IBD analyses for studying parasite population structure and resistance evolution in regions of low transmission, and emphasizes that drug resistance can evolve and spread in small populations, as will occur in any region nearing malaria elimination.

Analysis of interactions of actors of the knowledge network on malaria in Colombia

Introduction: Malaria is a disease with a high impact on Colombian population, which must be approached from the point of view of teamwork of institutions for knowledge exchange. Objective: To analyze the interactions of the Red de Gestión del Conocimiento, Investigación e Innovación en Malaria de Colombia. Materials and methods: An analysis of social networks was applied that allowed identifying the proximity between actors and the degree of knowledge between them. Indicators of density, diameter, average distance, and degree of centrality were observed. The documentary corpus for the study consisted of 193 technical documents published between 2016 and 2021, which were analyzed using text mining using the R programming language. The network was categorized based on five variables: comprehensive patient care, diagnosis, epidemiology and health information analysis systems, public policy and promotion and prevention. Results: The analysis of interactions indicated that the network was made up by 99 actors. The main interest in knowledge production was on epidemiology and health information analysis systems (98 % of the actors), followed by the integral patient care (80 % of the actors). On the contrary, the least approached category was malaria promotion and prevention practices (54 % of the actors). Conclusions: In general, this study contributes to the strengthening of key strategies in the dissemination of knowledge about malaria in Colombia.

Molecular surveillance for anti-malarial drug resistance and genetic diversity of Plasmodium falciparum after chloroquine and sulfadoxine-pyrimethamine withdrawal in Quibdo, Colombia, 2018

Background

Resistance to anti-malarial drugs is associated with polymorphisms in target genes and surveillance for these molecular markers is important to detect the emergence of mutations associated with drug resistance and signal recovering sensitivity to anti-malarials previously used.

Methods

The presence of polymorphisms in genes associated with Plasmodium falciparum resistance to chloroquine and sulfadoxine-pyrimethamine was evaluated by Sanger sequencing, in 85 P. falciparum day of enrollment samples from a therapeutic efficacy study of artemether–lumefantrine conducted in 2018–2019 in Quibdo, Colombia. Samples were genotyped to assess mutations in pfcrt (codons 72–76), pfdhfr (codons 51, 59, 108, and 164), and pfdhps genes (codons 436, 437, 540, and 581). Further, the genetic diversity of infections using seven neutral microsatellites (NMSs) (C2M34, C3M69, Poly α, TA1, TA109, 2490, and PfPK2) was assessed.

Results

All isolates carried mutant alleles for pfcrt (K76T and N75E), and for pfdhfr (N51I and S108N), while for pfdhps, mutations were observed only for codon A437G (32/73, 43.8%). Fifty samples (58.8%) showed a complete neutral microsatellites (NMS) profile. The low mean number of alleles (2 ± 0.57) per locus and mean expected heterozygosity (0.17 ± 0.03) showed a reduced genetic diversity. NMS multilocus genotypes (MMG) were built and nine MMG were identified.

Conclusions

Overall, these findings confirm the fixation of chloroquine and pyrimethamine-resistant alleles already described in the literature, implying that these drugs are not currently appropriate for use in Colombia. In contrast, mutations in the pfdhps gene were only observed at codon 437, an indication that full resistance to sulfadoxine has not been achieved in Choco. MMGs found matched the clonal lineage E variant 1 previously reported in northwestern Colombia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04328-x.

Malaria in the eco-epidemiological region of the Colombian Caribbean, 1960-2019

OBJECTIVES.

Motivation for the study: the information available on the epidemiology of malaria in the Colombian Caribbean region is incomplete, poorly systematized and its dissemination is limited. This has led to a lack of knowledge of its magnitude and a low perception of its importance as a public health problem. Main findings: the behavior of malaria is endemic-epidemic, with low to very low transmission, focused and with irregular outbreaks. Plasmodium vivax infections predominate. Implications: the results of this study contribute to improve evidence-based decision making for the implementation of malaria eradication plans. Malaria has a heterogeneous and variable behavior among Colombian regions. In order to establish its epidemiological behavior in the Colombian Caribbean region between 1960 and 2019, we carried out an observational, descriptive and retrospective study based on records from the Ministry of Health and other secondary sources. We defined epidemiological variables and used measures of frequency and central tendency. A total of 155,096 cases were registered. The decades with the highest number of cases were 1990-1999 (20.5%) and 1980-1989 (18.9%). The average number of cases per decade was 25,849.3. The highest parasite rates were recorded in 1970 (3.3 per 1000 population) and 1981 (3.9 per 1000 population). Plasmodium vivax was the most frequent species and most of the burden by age group was found in people under 29 years of age, between 2010-2019. Malaria showed an endemic-epidemic pattern of low and very low transmission intensity, with a decreasing trend.

Survey and Analysis of Chemoprophylaxis Policies for Domestic Travel in Malaria-Endemic Countries

The prevention of malaria in travelers with the use of antimalarials often occurs in connection with international travel to areas of significant risk of infection. Although these travelers sometimes cause outbreaks in their malaria-free home countries, the cardinal objective of prescribed chemoprophylaxis is to protect the traveler from patent malaria during travel. Here we consider the chemoprophylaxis of domestic travelers from malaria-free but -receptive areas within malaria-endemic countries. The main objective in this setting is the protection of those areas from reintroduced malaria transmission. In order to better understand policy and practices in this regard, we surveyed malaria prevention and treatment guidelines of 36 malaria-endemic countries and 2 that have recently eliminated malaria (Sri Lanka, China) for recommendations regarding malaria chemoprophylaxis for domestic travel. Among them, just 8 provided specific and positive recommendations, 1 recommended without specific guidance, and 4 advised against the practice. Most nations (25/38; 66%) did not mention chemoprophylaxis for domestic travel, though many of those did offer guidance for international travel. The few positive recommendations for domestic travel were dominated by the suppressive prophylaxis options of daily doxycycline or atovaquone-proguanil or weekly mefloquine. The incomplete protection afforded by these strategies, along with impractical dosing in connection with the typically brief domestic travel, may in part explain the broad lack of policies and practices across malaria-endemic nations regarding chemoprophylaxis.

A Follow-Up to the Geographical Distribution of Anopheles Species in Malaria-Endemic and Non-Endemic Areas of Honduras

Simple Summary

Malaria is a tropical disease caused by parasites of the genus Plasmodium. The parasite is transmitted to humans through the bite of the female mosquito Anopheles. Honduras is close to the goal of eliminating malaria, but the region called La Moskitia continues to concentrate almost all of the country’s malaria cases. One of the key factors in achieving malaria elimination is a thorough understanding of the mosquito vectors that transmit the disease. There are few studies related to malaria vectors in Honduras. This study aims to contribute to knowing which are the species of vector mosquitoes, mainly in the Department of Gracias a Dios and in other departments in which cases of malaria occur, in addition to describing molecularly for the first time the anophelines of the Bay Islands. The most abundant species found here were Anopheles albimanus, but seven other species were also identified, some of which may contribute to parasite transmission.

Abstract

Anopheles species are the vectors of malaria, one of the diseases with the greatest impact on the health of the inhabitants of the tropics. Due to their epidemiological relevance and biological complexity, monitoring of anopheline populations in current and former malaria-endemic areas is critical for malaria risk assessment. Recent efforts have described the anopheline species present in the main malaria foci in Honduras. This study updates and expands knowledge about Anopheles species composition, geographical distribution, and genetic diversity in the continental territory of Honduras as in the Bay Islands. Outdoor insect collections were carried out at 25 sites in eight municipalities in five departments of Honduras between 2018 and 2021. Specimens were identified using taxonomic keys. Partial COI gene sequences were used for molecular species identification and phylogenetic analyses. In addition, detection of Plasmodium DNA was carried out in 255 female mosquitoes. Overall, 288 Anopheles mosquitoes were collected from 8 municipalities. Eight species were morphologically identified. Anopheles albimanus was the most abundant and widely distributed species (79.5%). A subset of 175 partial COI gene sequences from 8 species was obtained. Taxonomic identifications were confirmed via sequence analysis. Anopheles albimanus and An. apicimacula showed the highest haplotype diversity and nucleotide variation, respectively. Phylogenetic clustering was found for An. argyritarsis and An. neomaculipalpus when compared with mosquitoes from other Neotropical countries. Plasmodium DNA was not detected in any of the mosquitoes tested. This report builds upon recent records of the distribution and diversity of Anopheles species in malaria-endemic and non-endemic areas of Honduras. New COI sequences are reported for three anopheline species. This is also the first report of COI sequences of An. albimanus collected on the island of Roatán with apparent gene flow relative to mainland populations.

Epidemiological evolution and historical anti-malarial control initiatives in Colombia, 1848-2019

The evolution of epidemiological transmission and the control measures implemented in Colombia have been the result of complex global and regional economic and political processes that occurred at different historical moments, since the dawn of the country's republican life. The development of economic activities for the production, exploitation and export of agricultural products, minerals and raw materials demanded in the international market, favored the necessary conditions for the emergence, expansion, resurgence and persistence of the endemic epidemic of malaria in the different stages studied. A common and fundamental element in the different defined historical moments was the importance given to malaria as an economic problem due to the negative externalities it imposed on the labor force. In addition, due to the role it played as a barrier that limited the exploitation of natural resources and raw materials of interest; as well as the impact that it caused to the flow and commercial exchange. The previous situation was framed with the growth, consolidation and geostrategic expansion of the United States, as the main commercial partner of the region, and its interest in the exploitation of resources and raw materials, cheap labor, the need to create new markets, which coincided with the goals of modernization and economic strengthening of Colombia. Taking into account different relevant milestones that occurred in the 1848-2019 period, the following stages were defined: Epidemiological emergence and re-emergence of tropical fevers in places of economic exploitation, 1848-1899;Emergence of a new paradigm, control in enclaves of economic interest, ports and cities, 1900-1949;Control to eradication, intensified control-eradication, prevention and control, 1950-1999;Prevention, control and elimination of malaria, 2000-2019. Historically, antimalarial control initiatives in the country have been directed, restricted and prioritized in places of political and economic importance. The technical-scientific intervention measures implemented in the different stages studied have been uncritically replicated without adapting to the epidemiological scenarios existing in the country. Finally, the antimalarial control measures implemented in Colombia have been imported and adopted from international health initiatives as a result of commitments and obligations acquired in the global commercial context.

Frequency of placental malaria and its associated factors in northwestern Colombia, pooled analysis 2009–2020

Knowledge about placental malaria (PM) is insufficient in the world, and incipient in Colombia where studies are few and recent. In this country, PM has been reported by Plasmodium vivax, Plasmodium falciparum, and mixed infection. The objective was to determine the frequency of PM and its associated clinical-epidemiological factors in mothers and neonates in northwestern Colombia, 2009–2020. A Retrospective pooled analysis with 602 placentas captured in five investigations. The diagnosis of PM was made with thick blood smear (TBS) and qPCR. The groups with and without PM were compared using the Chi-square test, Mann-Whitney test, and crude and adjusted prevalence ratios in a log-binomial model. The prevalence of PM was 27.7% with 92% (155/167) of submicroscopic cases; 41.3% by P. vivax, 44,3% by P. falciparum, and 14.4% by mixed infections. In the multivariate adjustment, PM was associated with the diagnosis of congenital malaria, low neonatal weight, gestational malaria, maternal anemia, previous malaria during pregnancy, and age between 25–43 years. This research is the investigation with the largest number of subjects for studying PM in Colombia, in the ecoepidemiological zone that produces more cases of malaria per year, finding a high prevalence of submicroscopic PM that caused serious maternal (anemia) and neonatal (congenital malaria and low neonatal weight) effects. The results show limitations in the timely diagnosis and treatment, given that the epidemiological surveillance program in Colombia is based on thick blood smear, which generates a substantial underestimation of the magnitude of PM, with serious effects and clinical risks. It is urgent to demand that the health authorities adopt measures such as prenatal control visits as soon as the pregnancy begins, monthly implementation of TBS, and active search for infected pregnant women in their homes and workplaces.

Malaria epidemics in Colombia, 1970-2019

Background:

Malaria has unstable transmission in Colombia and has variable endemic-epidemic patterns. This study describes the epidemiological characteristics of malaria epidemics registered in Colombia from 1970-2019.

Methods:

Data from 1979-2019 were collected from the National Public Health Surveillance System. The data was tabulated and pertinent descriptive analyses were carried out.

Results:

Fifteen malaria outbreaks and approximately five-year-long epidemic cycles were observed in Colombia during the study period.

Conclusions:

Malaria epidemics in Colombia present a five-yearly transmission pattern, mainly due to the increased vulnerability produced by seasonal population migrations in receptive areas with active transmission.