Political, climatic and socio-economic changes related to technology, transport and food security have affected society positively and negatively. They have affected the distribution patterns of parasites and vector arthropods, giving rise to foreign pathogens in new geographic areas. This incidence could eventually pose serious threats to public health. Globalization has also helped the emergence and spread of infectious diseases. Recently, researchers reviewed the incidence and management of emerging parasites and vectors associated with human and veterinary organisms. This review is available in a special issue of the journal Acta Tropica.
Study: Emerging parasites and vectors in a rapidly changing world: from ecology to management. Image credit: Eileen Kumpf / Shutterstock
Different aspects of emerging parasites and vectors
As a result of climate changes, parasites can now thrive in a variety of environments. In addition, they influence the patterns of occurrence and distribution of various other parasitic agents. For example, research has shown that both soft and hard ticks infest humans in Brazil. It is hypothesized that environmental changes caused by deforestation will cause a geographical expansion of some tick species and the pathogens associated with them.
In addition, researchers are actively studying public health and veterinary invasive mosquito species. The presence of Aedes koreicus and Aedes japonicus has already been reported in northern Italy and is almost certainly spreading to European countries soon. Other insects of veterinary importance (eg biting mosquitoes) have been studied in parts of Algeria, which are vectors of various pathogens. The assessment of their distribution and composition could be vital for planning control strategies.
The impact of wildlife on the emergence of parasites has been analyzed in several studies. Roe deer ticks Ixodes ricinus are known to carry a variety of arthropod-borne bacteria. In addition, there is a great diversity of ticks on birds along with Rickettsia spp. was reported in a study conducted in the Brazilian Atlantic Rainforest. Soft ticks were found inside a house in Brazil and were found to be molecularly positive for human blood. This finding is cause for concern as it shows how closely related these primarily wildlife ectoparasites and their pathogens are to humans.
It has been shown that the replacement of native forests with monocultures, such as pine plantations, could influence the spread of orally transmitted parasites (eg Giardia spp.). A number of dermatological conditions in humans are associated with parasites of zoonotic concern. Protozoa, helminths and arthropods are the key parasites that lead to these conditions. Researchers have analyzed these parasites that cause skin lesions and proposed the most appropriate treatment options.
Management strategies of parasitic diseases
Scientists around the world have been developing strategies to prevent and control the transmission of parasitic diseases. This is extremely important because parasites influence several mechanisms that hinder the effectiveness of many classes of drugs.
Biological tools, such as fungi, have been popularly used to manage parasitic diseases; however, this approach is extremely expensive. Recently, another method, the assisted self-diffusion technique, has been developed, which requires further improvements before its implementation. In this technique, target arthropod vectors are introduced with entomopathogenic fungi, which act directly or indirectly as propagators of other pests.
Extensive research has been conducted to manage veterinary and human associated endoparasites. For example, strategies have been formulated to eliminate Trypanosoma evansi, the causative agent of African camel distemper. Ringworm is a disease caused by the T evansi blood parasite, transmitted through biting flies.
Improvements in the capabilities of national veterinary services, such as disease diagnosis and control methods, have helped to control T evansi. In addition, application of integrated management and increased host resistance through improved immune status has helped control T evansi.
Doxycycline has been used for the slow treatment strategy of Dirofilaria immitis infection in dogs. This treatment focused on eliminating the Wolbachia endosymbiont and reducing the level of microfilariae in the blood.
Highly reliable and sensitive diagnostic tools are essential in the management of parasitic diseases. It is important not to solely target disease in vertebrate hosts to manage parasitic diseases. Instead, it could be beneficial to control the vector population. Interestingly, Germany-based honey bait Flinders Technology Associates (FTA) formulated a strategy to detect the circulation of Usutu virus in mosquito populations. This technique could be used in large-scale surveillance programs for the early detection of parasites.
Conclusions
The current study underscored the importance of controlling invasive arthropod vectors, as they can introduce foreign pathogens into geographic regions, adversely affecting animals and human populations. In addition, global warming and globalization have played a key role in helping to change the global distribution patterns of pathogens. Therefore, it is time to invest in the development of alternative management strategies to alleviate the socioeconomic impact of parasitic diseases.