Department of Comparative Pathobiology, Purdue University College of Veterinary Medicine, West Lafayette, IN 47907-2027, USA
Received Date: January 23, 2013; Accepted Date: January 25, 2013; Published Date: January 27, 2013
Citation: Camp JW (2013) Introduction to the Special Issue on Epidemiology and Ecology of Parasitic Diseases. J Clin Exp Pathol S3:e001. doi: 10.4172/2161-0681.S3:e001
Copyright: © 2013 Camp JW. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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The articles within this special issue of JCEP are varied in that some deal with human parasitic diseases while others cover parasitic diseases of veterinary medical importance. Of course, zoonotic relationships are inevitable and are also discussed in several papers. In spite of the varied topics of these papers, important themesinclude the impact of global and regional climate changes, habitat changes and poverty on the transmission and potential spread of these parasites.
Although not always recognized in the developed world, malaria is still a major scourge in many parts of the developing world. In 2000, it was estimated that 800,000 children died of malaria infections . In many malaria-endemic areas of the world, children are also malnourished . Prudence et al. examines the relationship between protein energy malnutrition and clinical malariain children at the time of hospitalization. Their study was done in the Democratic Republic of Congo (DRC) where malaria and malnutrition are significant pediatric health issues.Previous studies of the relationships between malaria and malnutrition have provided contradictory results. However, studies examining the influence of Protein Energy Malnutrition (PEM) on clinical malaria suggested lower survival rates in children exhibiting PEM who also had clinical malaria . The results of the current study suggest that clinical malaria is more common in severely malnourished children requiring therapeutic feeding. Interestingly, the results also suggest that there is an increased risk of clinical malaria occurring when nutritional rehabilitation is provided. The authors suggest that additional studies are needed to verify these results and that the relationship among malnutrition, therapeutic feeding and malaria is quite complex and little understood. This seems like a fruitful area of research with the potential to save the lives of many children, if funding can be obtained. In a follow-up paper, Prudence et al. examined the efficacy of Artesunate (AS) Plus Amodiaquine (AQ) as a treatment for falciparum malaria in malnourished children less than five years of age in the DRC. They found that the combination of AS and AQ had good efficacy for treating children under five years of age suffering from uncomplicated falciparum malaria who also suffered with severe acute malnutrition.
Human African Trypanosomiasis (HAT), commonly known as sleeping sickness is a vector-borne parasitic infection caused by protozoa of the genus Trypanosoma. It can be fatal if left untreated. HAT is found in sub-Saharan Africa, but is restricted to the range of its tsetse vector. In recent decades, the foci of HAT infections have changed and it has been suggested that climate change and changes to the habitats of the tsetse vectors have influenced the observed changes. The paper by Tongué et al. clearly demonstrates the effects of habitat change on the transmission of African trypanosomiasis. Certain subspecies of Glossina have adjusted to the decrease in natural habitats by exhibiting peri-domestic behaviors that allow them to live in urban and suburban habitats near humans. The increase in urban and suburban habitats for subspecies of the tsetse vector Glossina has reduced the effectiveness of efforts to control, much less eliminate, transmission of the causative species Trypanosoma brucei rhodesiense (causes the acute form of the disease) and Trypanosoma brucei gambiense (causes the chronic from of the disease). This study provides a cautionary tale about the influence of habitat changes and climate change on the future of HAT transmission (and other pathogens), assuming these changes continue to occur.
In the next study, we move west off of the continent of Africa to consider a species of mosquito in the genusCulex and its possible role in the transmission of Dirofilaria immitis, the primary causative agent of heartworm disease. Although the Canary Islands are a known endemic focus of Dirofilaria immitis, the mosquito vector on the island has, heretofore, not been identified. This article by Morchón García et al. provides convincing evidence that they found the mosquito species that serves as the vector of D. immitis on the islands. Five potential vector species of mosquitoes were collected on the islands. Using molecular biological techniques, the authors identified one species of mosquito, Culex theileri, which was infected with D. immitis. Recent studies in Iran  and Spain  suggest that C. theileri is a competent vector species. In addition, comparing analyses of the mtDNA in the cox1 gene between C. theileri populations in the Canary Islands and Iran suggest that the two populations are molecularly similar. Although the results of this study are supportive of the role of C. theileri in the transmission of D. immitis in the Canary Islands, the authors caution that additional studies are required to conclusively support their suggestions.
Our next study takes us to Asia and consideration of the status of Visceral Leishmaniasis (VL) in Iran. In his review, Mohebali combines his personal experience with numerous (>3,000) cases of leishmaniasis in Iran with results obtained from a search of databases from 1996 through 2010. The author’s results suggest that canids serve as the primary reservoir hosts of infection of humans a result found in previous studies . Several species of Phlebotomus serve the insect vectors in Iran. In Iran, VL appears to be a disease of the young as children 12 years of age and younger made up 92.8% of the reported cases of VL during the time span under review. Mohebali found that the direct agglutination test was an effective means of detecting anti- Leishmania antibodies and recommended it as a surveillance tool. The author concluded that VL is a serious zoonotic threat in Iran with sporadic prevalence in most geographic zones while being endemic in northwestern and southern Iran.
Finally, we go further east and north to Mongolia where Papageorgiou et al. examined the epidemiology of tick-borne pathogens in two of the country’s provinces (aimags). Livestock were investigated using serology and PCR to identify exposure and infection to several pathogens. The pathogens included Borrelia burgdorferi, Anaplasma phagocytophilum, A. ovis and spotted fever rickettsia species. These species are often pathogenic and have disease sequelae that can lead to economic hardship due to loss of production, culling of affected individuals and premature death [7,8]. The authors found differences between the two provinces as well as among the various species of livestock. These are nicely detailed in the article. This study is especially important as it constitutes the first effort in almost 50 years to investigate the presence of tick-borne pathogens in northern Mongolia. The authors note that there have been recent reports of newly identified Rickettsia and Borrelia species in neighboring provinces of northern China.These reports combined with the data from the current study emphasize the importance of further investigation of tick-borne pathogens to identify reservoir hosts and infection in Mongolian herders. The authors recognize that additional studies are necessary before concrete conclusions can be drawn, but their results suggest that Mongolia provides unique, while challenging, opportunities for additional research on tick-borne pathogens that affect domestic animals and humans.
Although not tied together closely by the subjects of their studies, these articles reinforce the importance of pursuing research on the numerous aspects of host-parasite interactions in both human and veterinary medicine. Such studies have the potential to provide important answers as well as directions for research to those dealing with these diseases especially in the developing world where the human and economic impacts can be the most devastating.
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