Toxoplasma gondii is an intracellular parasite involved in the etiology of various behavioral and hormonal alterations in humans and rodents. Various mechanisms, including induction changes of testosterone production,...Toxoplasma gondii is an intracellular parasite involved in the etiology of various behavioral and hormonal alterations in humans and rodents. Various mechanisms, including induction changes of testosterone production, have been proposed in the etiology of behavioral alterations during T. gondii infection. However, controversy remains about the effects of T. gondii infection on testosterone production; in some studies, increased levels of testosterone were reported, whereas other studies reported decreased levels. This is a significant point, because testosterone has been shown to play important roles in various processes, from reproduction to fear and behavior. This contradiction seems to indicate that different factors--primarily parasite strains and host variations--have diverse effects on the intensity of T. gondii infection, which consequently has diverse effects on testosterone production and behavioral alterations. This paper reviews the role of parasite strains, host variations, and intensity of T. gondii infection on behavioral alterations and testosterone production, as well as the role of testosterone in the etiology of these alterations during toxoplasmosis.展开更多
Background:Urinary schistosomiasis has been a major public health problem in Zambia for many years.However,the disease profile may vary in different locale due to the changing ecosystem that contributes to the risk of...Background:Urinary schistosomiasis has been a major public health problem in Zambia for many years.However,the disease profile may vary in different locale due to the changing ecosystem that contributes to the risk of acquiring the disease.The objective of this study was to quantify risk factors associated with the intensity of urinary schistosomiasis infection in school children in Lusaka Province,Zambia,in order to better understand local transmission.Methods:Data were obtained from 1912 school children,in 20 communities,in the districts of Luangwa and Kafue in Lusaka Province.Both individual-and community-level covariates were incorporated into an ordinal logistic regression model to predict the probability of an infection being a certain intensity in a three-category outcome response:0=no infection,1=light infection,and 2=moderate/heavy infection.Random effects were introduced to capture unobserved heterogeneity.Results:Overall,the risk of urinary schistosomiasis was strongly associated with age,altitude at which the child lived,and sex.Weak associations were observed with the normalized difference vegetation index,maximum temperature,and snail abundance.Detailed analysis indicated that the association between infection intensities and age and altitude were category-specific.Particularly,infection intensity was lower in children aged between 5 and 9 years compared to those aged 10 to 15 years(OR=0.72,95%CI=0.51-0.99).However,the age-specific risk changed at different levels of infection,such that when comparing children with light infection to those who were not infected,age was associated with a lower odds(category 1 vs category 0:OR=0.71,95%CI:0.50-0.99),yet such a relation was not significant when considering children who were moderately or heavily infected compared to those with a light or no infection(category 2 vs category 0:OR=0.96,95%CI:0.45-1.64).Overall,we observed that children living in the valley were less likely to acquire urinary schistosomiasis compared to those living in plateau areas(OR=0.48,95%CI:0.16-0.71).However,category-specific effects showed no significant association in category 1(light infection),whereas in category 2(moderate/high infection),the risk was still significantly lower for those living in the valley compared to those living in plateau areas(OR=0.18,95%CI:0.04-0.75).Conclusions:This study demonstrates the importance of understanding the dynamics and heterogeneity of infection in control efforts,and further suggests that apart from the well-researched factors of Schistosoma intensity,various other factors influence transmission.Control programmes need to take into consideration the varying infection intensities of the disease so that effective interventions can be designed.展开更多
Background:Ascariasis is one of the most important neglected tropical diseases of humans worldwide.The epidemiology of Ascaris infection appears to have changed with improvements in sanitation and mass drug administra...Background:Ascariasis is one of the most important neglected tropical diseases of humans worldwide.The epidemiology of Ascaris infection appears to have changed with improvements in sanitation and mass drug administration,but there is no recent information on prevalence worldwide.Here,we performed a systematic review and meta-analysis to assess the global prevalence of human Ascaris infection from 2010 to 2021.Methods:We searched MEDLINE/PubMed,and Scopus databases for studies measuring prevalence of Ascaris infection,published between 1 January 2010 and 1 January 2022.We included studies of the general human population in endemic regions,which used accepted coprodiagnostic methods,and excluded studies of people with occupations with an increased risk or probability of ascariasis and/or specifc diseases other than ascariasis.We applied randomefects models to obtain pooled prevalence estimates for six sustainable development goal regions of the world.We extrapolated the prevalence estimates to the global population in 2020,to estimate the number of individuals with Ascaris infection.We conducted multiple subgroup and meta-regression analyses to explore possible sources of heterogeneity,and to assess relationships between prevalence estimates and demographic,socio-economic,geoclimatic factors.Results:Of 11,245 studies screened,we analysed 758 prevalence estimates for a total number of 4,923,876 participants in 616 studies from 81 countries.The global prevalence estimated was 11.01%(95%confdence interval:10.27–11.78%),with regional prevalences ranging from 28.77%(7.07–57.66%)in Melanesia(Oceania)to 1.39%(1.07–1.74%)in Eastern Asia.We estimated that~732(682–782)million people harboured Ascaris worldwide in 2021.The infected people in Latin America and the Caribbean region had a higher prevalence of high intensity infection(8.4%,3.9–14.1%).Prevalence estimates were higher in children,and people in rural communities or in countries or regions with lower income and human development indices.There was a trend for a higher prevalence in regions with increasing mean annual relative humidity,precipitation and environmental temperature.Conclusions:Our fndings indicate that,despite a renewed commitment by some communities or authorities to control ascariasis,a substantial portion of the world’s human population(>0.7 billion)is infected with Ascaris.Despite the clinical and socioeconomic importance of ascariasis,many past routine surveys did not assess the intensity of Ascaris infection in people.We propose that the present fndings might stimulate the development of customised strategies for the improved control and prevention of Ascaris infection worldwide.展开更多
文摘Toxoplasma gondii is an intracellular parasite involved in the etiology of various behavioral and hormonal alterations in humans and rodents. Various mechanisms, including induction changes of testosterone production, have been proposed in the etiology of behavioral alterations during T. gondii infection. However, controversy remains about the effects of T. gondii infection on testosterone production; in some studies, increased levels of testosterone were reported, whereas other studies reported decreased levels. This is a significant point, because testosterone has been shown to play important roles in various processes, from reproduction to fear and behavior. This contradiction seems to indicate that different factors--primarily parasite strains and host variations--have diverse effects on the intensity of T. gondii infection, which consequently has diverse effects on testosterone production and behavioral alterations. This paper reviews the role of parasite strains, host variations, and intensity of T. gondii infection on behavioral alterations and testosterone production, as well as the role of testosterone in the etiology of these alterations during toxoplasmosis.
基金The first author(CS)received a travel award from the Danish Bilharziasis Laboratory,now the DBL-Centre for Health Research and Development,University of Copenhagen,DenmarkThe second author’s(LNK)efforts were partly funded by the University of Namibia.
文摘Background:Urinary schistosomiasis has been a major public health problem in Zambia for many years.However,the disease profile may vary in different locale due to the changing ecosystem that contributes to the risk of acquiring the disease.The objective of this study was to quantify risk factors associated with the intensity of urinary schistosomiasis infection in school children in Lusaka Province,Zambia,in order to better understand local transmission.Methods:Data were obtained from 1912 school children,in 20 communities,in the districts of Luangwa and Kafue in Lusaka Province.Both individual-and community-level covariates were incorporated into an ordinal logistic regression model to predict the probability of an infection being a certain intensity in a three-category outcome response:0=no infection,1=light infection,and 2=moderate/heavy infection.Random effects were introduced to capture unobserved heterogeneity.Results:Overall,the risk of urinary schistosomiasis was strongly associated with age,altitude at which the child lived,and sex.Weak associations were observed with the normalized difference vegetation index,maximum temperature,and snail abundance.Detailed analysis indicated that the association between infection intensities and age and altitude were category-specific.Particularly,infection intensity was lower in children aged between 5 and 9 years compared to those aged 10 to 15 years(OR=0.72,95%CI=0.51-0.99).However,the age-specific risk changed at different levels of infection,such that when comparing children with light infection to those who were not infected,age was associated with a lower odds(category 1 vs category 0:OR=0.71,95%CI:0.50-0.99),yet such a relation was not significant when considering children who were moderately or heavily infected compared to those with a light or no infection(category 2 vs category 0:OR=0.96,95%CI:0.45-1.64).Overall,we observed that children living in the valley were less likely to acquire urinary schistosomiasis compared to those living in plateau areas(OR=0.48,95%CI:0.16-0.71).However,category-specific effects showed no significant association in category 1(light infection),whereas in category 2(moderate/high infection),the risk was still significantly lower for those living in the valley compared to those living in plateau areas(OR=0.18,95%CI:0.04-0.75).Conclusions:This study demonstrates the importance of understanding the dynamics and heterogeneity of infection in control efforts,and further suggests that apart from the well-researched factors of Schistosoma intensity,various other factors influence transmission.Control programmes need to take into consideration the varying infection intensities of the disease so that effective interventions can be designed.
文摘Background:Ascariasis is one of the most important neglected tropical diseases of humans worldwide.The epidemiology of Ascaris infection appears to have changed with improvements in sanitation and mass drug administration,but there is no recent information on prevalence worldwide.Here,we performed a systematic review and meta-analysis to assess the global prevalence of human Ascaris infection from 2010 to 2021.Methods:We searched MEDLINE/PubMed,and Scopus databases for studies measuring prevalence of Ascaris infection,published between 1 January 2010 and 1 January 2022.We included studies of the general human population in endemic regions,which used accepted coprodiagnostic methods,and excluded studies of people with occupations with an increased risk or probability of ascariasis and/or specifc diseases other than ascariasis.We applied randomefects models to obtain pooled prevalence estimates for six sustainable development goal regions of the world.We extrapolated the prevalence estimates to the global population in 2020,to estimate the number of individuals with Ascaris infection.We conducted multiple subgroup and meta-regression analyses to explore possible sources of heterogeneity,and to assess relationships between prevalence estimates and demographic,socio-economic,geoclimatic factors.Results:Of 11,245 studies screened,we analysed 758 prevalence estimates for a total number of 4,923,876 participants in 616 studies from 81 countries.The global prevalence estimated was 11.01%(95%confdence interval:10.27–11.78%),with regional prevalences ranging from 28.77%(7.07–57.66%)in Melanesia(Oceania)to 1.39%(1.07–1.74%)in Eastern Asia.We estimated that~732(682–782)million people harboured Ascaris worldwide in 2021.The infected people in Latin America and the Caribbean region had a higher prevalence of high intensity infection(8.4%,3.9–14.1%).Prevalence estimates were higher in children,and people in rural communities or in countries or regions with lower income and human development indices.There was a trend for a higher prevalence in regions with increasing mean annual relative humidity,precipitation and environmental temperature.Conclusions:Our fndings indicate that,despite a renewed commitment by some communities or authorities to control ascariasis,a substantial portion of the world’s human population(>0.7 billion)is infected with Ascaris.Despite the clinical and socioeconomic importance of ascariasis,many past routine surveys did not assess the intensity of Ascaris infection in people.We propose that the present fndings might stimulate the development of customised strategies for the improved control and prevention of Ascaris infection worldwide.
