Multisectoral Perspectives on Global Warming and Vector-borne Diseases: a Focus on Southern Europe

Association of temperature and precipitation with malaria incidence in 57 countries and territories from 2000 to 2019: A worldwide observational study

Background

The transmission of malaria is known to be affected by climatic factors. However, existing studies on the impact of temperature and precipitation on malaria incidence offer no clear-cut conclusions, and there is a lack of research on a global scale. We aimed to estimate the association of temperature and precipitation with malaria incidence globally from 2000 to 2019.

Methods

We used meteorological data from the National Centers for Environmental Information and malaria incidence data from the Global Burden of Disease Study 2019 to calculate effect sizes through quasi-Poisson generalised linear models while controlling for confounders.

Results

231.4 million malaria cases occurred worldwide in 2019. National annual average temperature and precipitation were associated with malaria incidence, with an increase in the age-standardised incidence rate (ASIR) of 2.01% (95% confidence interval (CI) = 2.00, 2.02) and 6.04% (95% CI = 6.00, 6.09) following one unit increase of national annual average temperature and precipitation. In subgroup analysis, we found that malaria incidence in Asian countries was most affected by temperature, while the incidence in African countries was most affected by precipitation (P < 0.05). Stratified by age, children under five were most affected by both temperature and precipitation (P < 0.05). We additionally found that the impact of the national annual average temperature on malaria incidence increased over time (P < 0.05).

Conclusions

We advocate for a comprehensive approach to malaria prevention, focussed on addressing the impact of climate factors through international collaboration, adaptive measures, and targeted interventions for vulnerable populations.

Updates in Air Pollution: Current Research and Future Challenges

Background

The United Nations has declared that humans have a right to clean air. Despite this, many deaths and disability-adjusted life years are attributed to air pollution exposure each year. We face both challenges to air quality and opportunities to improve, but several areas need to be addressed with urgency.

Objective

This paper summarises the recent research presented at the Pacific Basin Consortium for Environment and Health Symposium and focuses on three key areas of air pollution that are important to human health and require more research.

Findings and conclusion

Indoor spaces are commonly places of exposure to poor air quality and are difficult to monitor and regulate. Global climate change risks worsening air quality in a bi-directional fashion. The rising use of electric vehicles may offer opportunities to improve air quality, but it also presents new challenges. Government policies and initiatives could lead to improved air and environmental justice. Several populations, such as older people and children, face increased harm from air pollution and should become priority groups for action.

Identifying Knowledge Gaps through the Systematic Review of Temperature-Driven Variability in the Competence of Aedes aegypti and Ae. albopictus for Chikungunya Virus

Temperature is a well-known effector of several transmission factors of mosquito-borne viruses, including within mosquito dynamics. These dynamics are often characterized by vector competence and the extrinsic incubation period (EIP). Vector competence is the intrinsic ability of a mosquito population to become infected with and transmit a virus, while EIP is the time it takes for the virus to reach the salivary glands and be expectorated following an infectious bloodmeal. Temperatures outside the optimal range act on life traits, decreasing transmission potential, while increasing temperature within the optimal range correlates to increasing vector competence and a decreased EIP. These relatively well-studied effects of other Aedes borne viruses (dengue and Zika) are used to make predictions about transmission efficiency, including the challenges presented by urban heat islands and climate change. However, the knowledge of temperature and chikungunya (CHIKV) dynamics within its two primary vectors-Ae. aegypti and Ae. albopictus-remains less characterized, even though CHIKV remains a virus of public-health importance. Here, we review the literature and summarize the state of the literature on CHIKV and temperature dependence of vector competence and EIP and use these data to demonstrate how the remaining knowledge gap might confound the ability to adequately predict and, thus, prepare for future outbreaks.

Molecular identification of phlebotomine sand flies and the harbored Leishmania spp. in Sokoto State, Nigeria

Introduction

Female sand flies are hematophagous, feeding on animals and in the process serve as vectors for Leishmania, the parasites that cause leishmaniasis in humans. Leishmaniasis are a group of parasitic neglected tropical diseases in 98 countries including Nigeria and kills ~60,000 people/year. In Nigeria, Sokoto State is endemic to leishmaniasis but there is a knowledge gap on the identity of the prevalent sand flies and the Leishmania species they transmit. Hence, this cross-sectional study was designed to take inventory of the species of sand flies in Sokoto using genetic methods.

Methods

1,260 (310 females) sand flies were collected from three Local Government Areas (L.G.A) of Sokoto State- Wamakko, Sokoto South and Kware. Genomic DNA was extracted from each fly and DNA amplification by polymerase chain reaction (PCR) was carried out on the DNA samples using primers targeting the arthropods mitochondrial cytochrome oxidase subunit 1 (mt-coI) gene, and nested PCR with primers targeting the gene for Leishmania internal transcribed spacer-1 (its-1) of ribosomal RNA its-1rRNA. The PCR products were sequenced.

Results

Gene sequence analysis revealed five species of sand flies belonging to the old-world genera namely Phlebotomus and Sergentomyia. The identified species were P. papatasi (6.45%), S. adleri (6.45%), S. affinis (9.7%), S. distincta (9.7%), S. schwetzi (67.7%). Within the sampling period, sand flies were most abundant in the rainy months of August (104/33.5%) and September (116/37.4%) with all the five identified species occurring. Sequence analysis of its-1 gene identified Leishmania infantum in two sand flies (2/310)- P. papatasi (from Sokoto South) and S. affinis (from Wamakko). BLAST search in NCBI and phylogenetic analysis revealed that the sand fly species are related to the species reported in different parts of Africa, while the L. infantum is identical to strain reported in Brazil (KY379083.1).

Discussion

Phlebotomus papatasi and four species belonging to the genus Sergentomyia are the most prevalent sand flies in Sokoto State, Nigeria and they harbor L. infantum solely. The results shed light on why visceral leishmaniasis is the most predominant form of the disease. Therefore, we recommend that adequate care for dogs must be instituted as dogs are the major animal reservoir for L. infantum.