Evaluation of the economic impact of brucellosis in domestic yaks of Tibet

Brucellosis is considered as an endemic disease in yaks (Bos grunniens) in China, but few economic analyses describing the cost of the disease and potential benefits of control have been reported. The aim of the study was to estimate the economic cost of brucellosis in yaks and the economic value of three control strategies: (a) vaccination; (b) test‐and‐slaughter; and (c) a combination of vaccination and test‐and‐slaughter programs in Damxung and Maizhokunggar counties and Pali township of Yadong county in Tibet. Using data from a cross‐sectional seroprevalence survey conducted in 2015, combined with financial data, the predicted costs and benefits of the different control strategies were simulated over a 6‐year period. The annual estimated cost of brucellosis in yaks within the study area was US$ 521,043 (95% CI: US$ 334,441; US$ 759,862), with an annual average cost per yak estimated at US$ 1.42 (95% CI: US$ 0.91, US$ 2.07). The benefit‐cost analysis predicted that vaccination was the most effective control method with a benefit‐cost ratio (BCR) of 3.19 (95% CI: 2.17, 4.66) and a net present value (NPV) of US$ 313,355 (95% CI: US$ 157,679, US$ 541,062) over a 6‐year period. A sensitivity analysis found the NPV was most sensitive to the loss from a female yak aborting in the vaccination control program. In contrast, the price of yaks that were slaughtered had the largest influence on the NPV for both the test‐and‐slaughter control program and the combination control program. These estimates provide valuable information and establish a foundation for formulating and implementing cost‐effective measures for controlling the disease in yaks on the Tibetan plateau, and more broadly in China.     

Prevalence of caprine brucellosis on herds of toba communities in Villa Río Bermejito,Chaco, Argentina (October 2010)

The purpose of this study was to evaluate the prevalence of caprine brucellosis in goat herds in a region known as ‘The Impenetrable’ in Chaco Province, Argentina, in order to prevent the occurrence of the disease in people consuming goats’ milk. There are high levels of child malnutrition and difficulties in accessing high‐quality protein in this region; therefore, goats’ milk is a valuable nutrition source. We travelled with Patricia Sosa's foundation ‘Little gestures, big results’ to Villa Río Bermejito, Chaco, in October 2010 with the laboratory equipment needed to carry out field tests. The foundation is staffed by voluntary workers, including doctors, dentists, experts in social issues, psychologists, who encourage the community to consume goats’ milk in their meals after cooking or pasteurizing it to avoid contamination. Blood samples were taken from 273 goats distributed in 13 herds established in the depth of Chaco dry forest that had not been vaccinated against brucellosis. Samples were analysed using the buffered plate antigen test, and positive results were confirmed using the slow agglutination test. Animals were identified using small plastic ear tags. We found only one positive case, with a titre of 1/50. This was considered suspicious and the owner was advised to take the animal out of the herd. Our results indicate that the isolation of these herds in the depths of the forest has protected them from brucellosis, and therefore, they are a good source of high‐quality protein, which the people of this region need.     

The epidemiology and hotspots of road traffic injuries in Moshi,Tanzania: An observational study

Road traffic injuries (RTIs) continue to increase with the proliferation of motor vehicles, especially in low-income countries where safe road infrastructure is lacking. Knowing where and why RTIs occur would allow for increased safety and prevention planning. In this study, police records of 300 motor vehicle collisions which occurred between February 2013 and January 2014 in Moshi, Tanzania were reviewed. Analysis of variables including victim age, gender, type of collision, conditions, and use of safety equipment were analyzed. Geographic information system (GIS) analysis was performed to identify areas with the most collisions. Most injuries occurred at four intersections on two main corridor. Car crashes represented 48% of reports while motorcycle collisions were 35% of reports. Victims were predominantly male. The majority (64%) of RTI victims in cars used seatbelts while only 43% of motorcyclists wore helmets; none of those who used the helmet or seatbelt suffered a grievous injury. These data demonstrate that RTIs in Moshi occur in predictable high traffic locations. RTIs injure victims of all backgrounds and safety equipment is not universally utilized. More investment is needed in improved data collection methods, and a greater emphasis on intersection safety is needed to reduce these preventable injuries.     

An estimate of the incidence and quantitative risk assessment of human brucellosis in mainland China

Two epidemiological models were applied to simulate whether animals with latent infections were contagious and calculate the outcomes of people that contracting brucellosis by all possible transmission routes under control measures implemented by the Chinese government. The health and economic burden of brucellosis overall presented an increasing trend from 2004 to 2017. Scenarios from epidemiological models showed that a larger scale of vaccine coverage would contribute to fewer infections in livestock and humans. S2 vaccine, the disinfection of the environment and the protection of the susceptible animals and humans could effectively reverse the trend of increasing brucellosis and reduce the incidence rates of brucellosis in humans to curb the epidemic of brucellosis in China.     

Bovine Tuberculosis and Brucellosis in Cattle and African Buffalo in the Limpopo National Park,Mozambique

Bovine tuberculosis (BTB) and brucellosis are prevalent in buffaloes of the Kruger National Park (KNP, South Africa). Both diseases were considered to have no or a very low prevalence in wildlife and livestock in and around the Limpopo National Park (LNP, Mozambique). The same applies for tuberculosis in Gonarezhou National Park (GNP, Zimbabwe), but just recently, BTB was detected in buffaloes in the GNP and fears arose that the disease might also spread to the LNP as a result of the partial removal of the fences between the three parks to form the Great Limpopo Transfrontier Park. To assess the status of both diseases in and around LNP, 62 buffaloes were tested for bovine tuberculosis (BTB) and bovine brucellosis. The percentage of positive BTB reactors in buffalo was 8.06% using BovidTB Stat‐Pak^® and 0% with BOVIGAM^® IFN‐γ test and IDEXX ELISA. The brucellosis seroprevalence in buffalo was found to be 17.72% and 27.42% using Rose Bengal Test (RBT) and ELISA, respectively. In addition, 2445 cattle in and around the LNP were examined for BTB using the single intradermal cervical comparative tuberculin test (SICCT), and an apparent prevalence of 0.98% was found with no significant difference inside (0.5%) and outside (1.3%) the park. This is the first published report on the presence of positive reactors to BTB and bovine brucellosis in buffalo and cattle in and outside the LNP. Monitoring the wildlife–livestock–human interface of zoonotic high‐impact diseases such as BTB and brucellosis is of outmost importance for the successful implementation and management of any transfrontier park that aims to improve the livelihoods of the local communities.     

Seroprevalence of brucellosis in goats and sheep in Thailand: Results from the Thai National Brucellosis Surveillance System from 2013 to 2015

In Thailand, brucellosis re‐emerged in humans in 2003 and is considered a public health risk to goat farmers as the disease is endemic in small ruminants. The Thai Department of Livestock Development (DLD ) established a nationwide surveillance system for brucellosis in goats and sheep in 1997. Using data from this surveillance system, we describe the seroprevalence of brucellosis from 2013 to 2015 in small ruminants and the spatial distribution of the disease throughout Thailand. Surveillance data collected included the number of animals and herds tested, the province of the animal and herd and the laboratory results. Seroprevalence was estimated at both the animal and herd levels. During the 3‐year period, 443,561 goats and sheep were tested for brucellosis by the DLD throughout Thailand using the Rose Bengal Plate Test (RBPT ) and the enzyme‐linked immunosorbent assay test for Brucella . Among the 3 years, 2013 had the highest proportion of herds that tested positive for brucellosis at 13.80% (95% CI, 12.52, 15.16). Overall, this study found that brucellosis seroprevalence in small ruminants is decreasing throughout Thailand. However, there is variability in the spread of the disease with provinces in the eastern and western regions of Thailand having higher proportions of animals and herds testing positive. Overall provinces in the south had the lowest proportion of animals and herds testing positive for brucellosis. Periodic review of surveillance data documents the impact of the current brucellosis control programme and supports a targeted response in higher prevalence regions when there are limited financial resources for control measures.     

Symptomatic and asymptomatic cases of African swine fever in Tanzania

African swine fever (ASF) is an acute, highly contagious and deadly viral haemorrhagic disease of domestic pigs caused by African swine fever virus (ASFV). In ASF endemic countries, there are an increasing number of reports on circulating ASFV strains with different levels of virulence causing a broad range of clinical symptoms in susceptible animals. Tanzania, where ASFV is endemic since 2001, recorded several outbreaks including symptomatic and asymptomatic cases between 2015 and 2017. We collected 35 clinical samples from four outbreaks for diagnostic confirmation and sequenced the partial B646L (p72), the full E183L (p54) gene, the central variable region of the B602L gene and the intergenic region between the I73R and I329L genes to characterize molecularly the new ASFV isolates and analyse their relatedness with previously reported Tanzanian and foreign isolates. We detected ASFV in 21 samples, 15 from symptomatic and six from asymptomatic pigs. Phylogenetic analyses based on the partial p72 gene and the complete p54 (E183L) genes revealed that the ASFVs in samples from symptomatic pigs belonged to genotypes II and those in samples from asymptomatic pigs belonged to genotype IX. The CVR profiles of the p72 genotype II and genotype IX isolates differed between each other and from previously published Tanzanian sequences. The sequence analysis of the intergenic region between the I73R and I329L for the 2017 genotype II isolates showed the absence of one GGAATATATA motif in those isolates. This study showed the simultaneous circulation of two different ASFV genotypes with different levels of pathogenicity in Tanzania. Since the existence of sub‐clinically infected pigs may contribute to the persistence of the virus, our findings suggest continuous surveillance and characterization of ASFV isolates in disease‐endemic regions.     

The Prevalence of Brucellosis in Cattle,Goats and Humans in Rural Uganda: A Comparative Study

A cross‐sectional study was conducted to determine the presence of brucellosis in cattle, goats and humans in farms from south‐western Uganda and identify risk factors associated with brucellosis in these three host groups. Data and serum samples were collected from 768 cattle, 315 goats and 236 humans, with 635 samples of bovine milk, from 70 farms in two different study areas in south‐western Uganda. Sera from livestock were tested with the Rose Bengal Plate test, using B. abortus and B. melitensis antigens, and human sera were tested with a commercial IgG/IgM lateral flow assay. Milk samples were tested using the OIE‐approved milk ring test. Screening tests for brucellosis were positive in 14% of cattle serum, 29% of bovine milk, 17% of goat serum and 11% of human serum samples. There were significant differences in the test prevalence of brucellosis by study site, with levels higher in the study area near Lake Mburo National Park than in the study area near Queen Elizabeth National Park. Multivariable regression models identified risk factors associated with increasing test positivity at the individual and farm levels for cattle, goats and humans. Positive associations were seen between increasing seropositivity of brucellosis in goats, cattle and humans. Results of multivariable analyses suggest that improvements in farm biosecurity and hygiene may reduce the risk of brucellosis on the farm and suggest a role for ticks in bovine brucellosis. Although cattle are the focus of brucellosis control in Uganda, the significant associations between seropositivity in humans and seropositivity in goats suggest that brucellosis in goats may be an important contributor to the epidemiology of the disease on the farm.     

Risky behaviours among young people living with HIV attending care and treatment clinics in Dar Es Salaam,Tanzania: implications for prevention with a positive approach

Introduction

Prevention with a positive approach has been advocated as one of the main strategies to reduce new instances of HIV infection. Risky sexual behaviours among people living with HIV/AIDS are the cornerstone for this approach. Understanding the extent to which infected individuals practice risky behaviours is fundamental in designing appropriate population-specific interventions. With the HIV infection transmission rates remaining high among young people in sub-Saharan Africa, continued prevention among them remains a priority. This study therefore seeks to describe the magnitude and determinants of risky sexual behaviours among young people living with HIV.

Methods

A cross-sectional study was conducted between June and July 2010 in selected Care and Treatment Clinics (CTCs) in Dar Es Salaam, Tanzania. A total of 282 HIV-positive patients aged 15–24 were interviewed about their sexual behaviours using a questionnaire.

Results

Prevalence of unprotected sex was 40.0% among young males and 37.5% among young females (p<0.001). Multiple sexual partnerships were reported by 10.6% of males and 15.9% of females (p<0.005). More than 50% of the participants did not know about the HIV status of their sexual partners. A large proportion of participants had minimal knowledge of transmission (46.7% males vs. 60.4% females) and prevention (65.3% males vs. 73.4% females) of sexually transmitted infections (STIs). Independent predictors of condom use included non-use of alcohol [adjusted odds ratio (AOR), 0.40 95% confidence interval (CI); 0.17–0.84] and younger age (15–19 years) (AOR, 2.76, 95% CI: 1.05–7.27). Being on antiretroviral therapy (AOR, 0.38, 95% CI: 0.17–0.85) and not knowing partners’ HIV sero-status (AOR, 2.62, 95% CI: 1.14–5.10) predicted the practice of multiple sexual partnership.

Conclusions

Unprotected sex and multiple sexual partnerships were prevalent among young people living with HIV. Less knowledge on STI and lack of HIV disclosure increased the vulnerability and risk for HIV transmission among young people. Specific intervention measures addressing alcohol consumption, risky sexual behaviours, and STI transmission and prevention knowledge should be integrated in the routine HIV/AIDS care and treatment offered to this age group.     

Predictors of mortality among adolescents and young adults living with HIV on antiretroviral therapy in Dar es Salaam,Tanzania: a retrospective cohort study

IntroductionGlobal AIDS‐related deaths have declined by only 10% among adolescents since its peak in 2003. This is disproportionately low compared to a decline of 74% among children aged 0–9 years old. We determined the magnitude of, and predictors of mortality among adolescents and young adults living with HIV on antiretroviral therapy (ART) in Dar‐es‐Salaam, Tanzania.MethodsA retrospective cohort study was conducted among adolescents (aged 10–19) and young adults (aged 20–24) living with HIV and enrolled in care and treatment centres in Dar es Salaam, Tanzania between January 2015 and December 2019. Data were analysed using STATA version 16. Cumulative hazard curves were used to estimate and illustrate 1‐year mortality. Predictors for mortality were assessed by the Fine and Gray competing risk regression model. Sub‐hazard ratios (SHR) and 95% confidence intervals (95% CI) were then reported.ResultsA total of 15,874 young people living with HIV were included: 4916 (31.3%) were adolescents and 10,913 (68.7%) were young adults. A total of 3843 (77.5%) adolescents and 9517 (87.2%) young adults were female. Deaths occurred in 2.3% (114/4961) of adolescents and 1.2% (135/10,913) of young adults (p < 0.001). Over a follow‐up of 9292 person‐years, the mortality rate was 3.8 per 100 person years [95% CI 3.2–4.6/100 person‐years] among adolescents and 2.1 per 100 person‐years among young adults [95% CI 1.8–2.5/100 person‐years]. Independent predictors of mortality among adolescents were male sex (adjusted (SHR) aSHR = 1.90, 95% CI: 1.3–2.8), CD4 count < 200 cells/mm³ (aSHR = 2.7, 95% CI: 1.4–5.0) and attending a private health facility (aSHR = 1.7, 95% CI: 1.1–2.5). Predictors of mortality among young adults were CD4 count < 200 cells/mm³ (aSHR = 2.8, 95% CI 1.7–4.5), being underweight (aSHR = 2.1, 95% CI: 1.4–3.3) and using nevirapine‐based therapy (aHR = 8.3, 95% CI: 3.5–19.5).ConclusionsThe mortality rate for persons living with HIV and on ART in Tanzania was significantly higher in adolescents than young adults. Age‐ and sex‐specific risk factors identify targets for intervention to reduce mortality among affected adolescents and young adults.     

Detection of African Swine Fever Virus DNA in Blood Samples Stored on FTA Cards from Asymptomatic Pigs in Mbeya Region,Tanzania

The aim of the study was to assess whether blood samples collected onto FTA^® cards could be used in combination with real‐time PCR for the detection of African swine fever virus (ASFV) DNA in samples from resource‐poor settings under the assumption that asymptomatically (sub‐clinically) infected pigs may be present. Blood samples were collected from clinically healthy pigs from Mbeya Region, Tanzania. The blood samples were stored on FTA^® cards and analysed by real‐time PCR assays in duplicate; three pigs had high levels of viral DNA (Ct values of 27–29), and three pigs had a low level of viral DNA (Ct 36–45). Four pigs were positive in one of the duplicate samples only, but clear products of the expected size were obtained when the reactions were analysed by gel electrophoresis. For comparison, blood samples from pigs experimentally infected with either a pathogenic (OURT T88/1) or a non‐pathogenic (OURT T88/3) isolate of ASFV were collected, stored on FTA^® cards and analysed in the same way. The blood from pigs infected with the OURT T88/1 isolate showed high levels of viral DNA (Ct 22‐33), whereas infection with non‐pathogenic OURT T88/3 isolate resulted in only low levels of viral DNA (Ct 39) in samples collected at 10–14 days after inoculation.     

Modelling the impact of HIV and HCV prevention and treatment interventions for people who inject drugs in Dar es Salaam,Tanzania

IntroductionPeople who inject drugs (PWID) in Dar es Salaam, Tanzania, have a high prevalence of HIV and hepatitis C virus (HCV). While needle and syringe programmes (NSP), opioid agonist therapy (OAT) and anti‐retroviral therapy (ART) are available in Tanzania, their coverage is sub‐optimal. We assess the impact of existing and scaled up harm reduction (HR) interventions on HIV and HCV transmission among PWID in Dar es Salaam.MethodsAn HIV and HCV transmission model among PWID in Tanzania was calibrated to data over 2006–2018 on HIV (∼30% and ∼67% prevalence in males and females in 2011) and HCV prevalence (∼16% in 2017), numbers on HR interventions (5254 ever on OAT in 2018, 766–1479 accessing NSP in 2017) and ART coverage (63.1% in 2015). We evaluated the impact of existing interventions in 2019 and impact by 2030 of scaling‐up the coverage of OAT (to 50% of PWID), NSP (75%, both combined termed “full HR”) and ART (81% with 90% virally suppressed) from 2019, reducing sexual HIV transmission by 50%, and/or HCV‐treating 10% of PWID infected with HCV annually.ResultsThe model projects HIV and HCV prevalence of 19.0% (95% credibility interval: 16.4–21.2%) and 41.0% (24.4–49.0%) in 2019, respectively. For HIV, 24.6% (13.6–32.6%) and 70.3% (59.3–77.1%) of incident infections among male and female PWID are sexually transmitted, respectively. Due to their low coverage (22.8% for OAT, 16.3% for NSP in 2019), OAT and NSP averted 20.4% (12.9–24.7%) of HIV infections and 21.7% (17.0–25.2%) of HCV infections in 2019. Existing ART (68.5% coverage by 2019) averted 48.1% (29.7–64.3%) of HIV infections in 2019. Scaling up to full HR will reduce HIV and HCV incidence by 62.6% (52.5–74.0%) and 81.4% (56.7–81.4%), respectively, over 2019–2030; scaled up ART alongside full HR will decrease HIV incidence by 66.8% (55.6–77.5%), increasing to 81.5% (73.7–87.5%) when sexual risk is also reduced. HCV‐treatment alongside full HR will decrease HCV incidence by 92.4% (80.7–95.8%) by 2030.ConclusionsCombination interventions, including sexual risk reduction and HCV treatment, are needed to eliminate HCV and HIV among PWID in Tanzania.     

The socioeconomic factors surrounding the initial emergence of peste des petits ruminants in Kenya,Uganda, and Tanzania from 2006 through 2008

Peste des petits ruminants (PPR) is a devastating disease of small ruminants that significantly hinders productivity in endemic areas. Kenya, Uganda and Tanzania reported their first cases in each country between 2006 and 2008 despite the disease being present in the region (Ethiopia and Sudan) since the 1990s. The time leading up to the outbreaks involved refugee movements, drought, civil unrest, and resulted in increased animal mingling, movement and density in these regions. Refugee camps with animal source food demands and a robust informal economy further added to the development of animal mingling and movement as well. Once introduced, common pastoral migration lands and trade routes likely transported the disease throughout the region. This paper highlights why trade routes, refugee camps and areas of animal crowding during droughts should be targeted for interventions, monitoring and surveillance as part of PPR control in a region.     

Genetic diversity of pathogenic leptospires from wild,domestic and captive host species in Portugal

Leptospirosis is a neglected zoonotic disease of worldwide distribution with a significant veterinary and public health impact. It is caused by pathogenic bacteria of the genus Leptospira. The availability of effective tools to accurately identify and type leptospires is of utmost importance for the diagnosis of the disease and for assessing its epidemiology. Several multi‐locus sequence typing (MLST) approaches were described for the typing of worldwide isolates of Leptospira but an extensive agreement towards the adoption of a unique consensus scheme for this agent is still lacking. Most genotyped strains originate from Asian and South American countries, with a minority originating from Europe (being most countries represented only by one or a few isolates). The knowledge of the diversity of circulating leptospires is the key to understanding the disease transmission and its zoonotic implications. In this study, we revisited the taxonomy of several isolates of pathogenic Leptospira obtained from domestic, wild and captive animals in Portugal, between 1990 and 2012. A selection of these isolates was genotyped using two previously published MLST schemes. A total of seven distinct sequence types (STs) were detected among the Portuguese isolates with two STs representing L. borgpetersenii (ST149 and ST152), two STs representing L. kirschneri (ST117 and ST100) and three STs representing L. interrogans (ST17, ST24 and ST140). Global widespread (and maybe more virulent) Leptospira genotypes seem to circulate in Portugal, particularly the L. interrogans ST17 isolates which are associated with several outbreaks of leptospirosis among humans and animals in different regions of the world. This study contributes to the enrichment of the global MLST databases with a new set of allele and sequence type information also providing novel data on circulating Leptospira serovars in Portugal.     

Spermiotoxicity of commercial condoms made from polyurethane,polyisoprene and latex,using domestic ruminants as an experimental animal model

The use of condoms could provide a means of collecting high‐quality spermatozoa from different species under physiological ejaculation conditions. However, certain condom materials may affect sperm functionality. This study examined the spermiotoxicity of different commercial condom materials towards ram and goat spermatozoa. Sperm samples were diluted in Tyrode's medium and placed in contact with a piece of condom material (polyurethane, polyisoprene or latex) and incubated for 30 or 90 min. Contact time in the polyisoprene and latex treatments affected some sperm variables; no such effects were seen, however, in the polyurethane treatments. For ram spermatozoa in contact with polyisoprene, the percentage of dead spermatozoa with a damaged acrosome increased at 90 min, while for spermatozoa in contact with latex, the percentage of live spermatozoa with an intact acrosome decreased. For goat spermatozoa in contact with both polyisoprene and latex, the percentage of dead spermatozoa with a damaged acrosome increased at 90 min, while for spermatozoa in contact with polyisoprene, the percentage of live spermatozoa with an intact acrosome decreased. In conclusion, latex and polyisoprene contain components that affect sperm motility, plasma membrane integrity and acrosome function. Polyurethane does not seem to reduce the quality of semen.     

An Integrative Genetics Approach to Identify Candidate Genes Regulating BMD: Combining Linkage,Gene Expression,and Association

Numerous quantitative trait loci (QTLs) affecting bone traits have been identified in the mouse; however, few of the underlying genes have been discovered. To improve the process of transitioning from QTL to gene, we describe an integrative genetics approach, which combines linkage analysis, expression QTL (eQTL) mapping, causality modeling, and genetic association in outbred mice. In C57BL/6J × C3H/HeJ (BXH) F₂ mice, nine QTLs regulating femoral BMD were identified. To select candidate genes from within each QTL region, microarray gene expression profiles from individual F₂ mice were used to identify 148 genes whose expression was correlated with BMD and regulated by local eQTLs. Many of the genes that were the most highly correlated with BMD have been previously shown to modulate bone mass or skeletal development. Candidates were further prioritized by determining whether their expression was predicted to underlie variation in BMD. Using network edge orienting (NEO), a causality modeling algorithm, 18 of the 148 candidates were predicted to be causally related to differences in BMD. To fine‐map QTLs, markers in outbred MF1 mice were tested for association with BMD. Three chromosome 11 SNPs were identified that were associated with BMD within the Bmd11 QTL. Finally, our approach provides strong support for Wnt9a, Rasd1, or both underlying Bmd11. Integration of multiple genetic and genomic data sets can substantially improve the efficiency of QTL fine‐mapping and candidate gene identification.     

Segmentation of subcomponents within the superior longitudinal fascicle in humans: a quantitative, in vivo, DT-MRI study

Previous research in non-human primates has shown that the superior longitudinal fascicle (SLF), a major intrahemispheric fiber tract, is actually composed of four separate components. In humans, only post-mortem investigations have been available to examine the trajectory of this tract. This study evaluates the hypothesis that the four subcomponents observed in non-human primates can also be found in the human brain using in vivo diffusion tensor magnetic resonance imaging (DT-MRI). The results of our study demonstrated that the four subdivisions could indeed be identified and segmented in humans. SLF I is located in the white matter of the superior parietal and superior frontal lobes and extends to the dorsal premotor and dorsolateral prefrontal regions. SLF II occupies the central core of the white matter above the insula. It extends from the angular gyrus to the caudal-lateral prefrontal regions. SLF III is situated in the white matter of the parietal and frontal opercula and extends from the supramarginal gyrus to the ventral premotor and prefrontal regions. The fourth subdivision of the SLF, the arcuate fascicle, stems from the caudal part of the superior temporal gyrus arches around the caudal end of the Sylvian fissure and extends to the lateral prefrontal cortex along with the SLF II fibers. Since DT-MRI allows the precise definition of only the stem portion of each fiber pathway, the origin and termination of the subdivisions of SLF are extrapolated from the available data in experimental material from non-human primates.