Infections caused by DNA viruses

Author(s):  
Philippa C. Matthews

This chapter consists of short notes, diagrams, and tables to summarize DNA viruses that are significant causes of disease in the tropics and subtropics. This includes pox viruses and hepatitis B virus. For ease of reference, each topic is broken down into sections, including classification, epidemiology, microbiology, pathophysiology, clinical syndromes, diagnosis, treatment, and prevention

2020 ◽  
Author(s):  
Fazle Rabbi Chowdhury ◽  
Anna L McNaughton ◽  
Mohammad Robed Amin ◽  
Lovely Barai ◽  
Mili Rani Saha ◽  
...  

ABSTRACTBangladesh is one of the world’s top ten burdened countries for viral hepatitis. We investigated an adult fever cohort (n=201) recruited in Dhaka, to determine the prevalence of hepatitis B virus (HBV) infection and to identify cases of occult hepatitis B infection (OBI). HBV exposure (anti-HBc) was documented in 72/201 (36%), and active HBV infection in 16/201 (8%), among whom 3 were defined as OBI (defined as detectable HBV DNA but negative HBsAg). Applying a target-enrichment sequencing pipeline to samples with HBV DNA >3.0log10 IU/ml, we obtained deep whole genome sequences for four cases, identifying genotypes A, C and D. Polymorphisms in the surface gene of the OBI case may account for the negative HBsAg status. We identified mutations associated with nucleos(t)ide analogue resistance, although the clinical significance in this cohort is not known. The high prevalence of HBV in this setting highlights the benefits of offering screening in hospital patients and the importance of HBV DNA testing of transfusion products to reduce the risk of transmission. In order to work towards international Sustainable Development Goal targets for HBV elimination, increased investment is required for diagnosis, treatment and prevention in Bangladesh.


2018 ◽  
Vol 3 (6) ◽  
pp. 383-403 ◽  
Author(s):  
Devin Razavi-Shearer ◽  
Ivane Gamkrelidze ◽  
Mindie H Nguyen ◽  
Ding-Shinn Chen ◽  
Pierre Van Damme ◽  
...  

2018 ◽  
Vol 8 (2) ◽  
pp. 75-79 ◽  
Author(s):  
Mukkaram Ali ◽  
Fauzia Imtiaz ◽  
Muhammad Ahsan Rehman Khan ◽  
Zaeem-ur-Rehman Khan ◽  
Bilal Ahmad ◽  
...  

Background: To assess awareness levels of Hepatitis B virus infection, transmission, treatment and prevention in medical and nonmedical students of Karachi. Methods: Undergraduate students in 6 medical and non-medical universities were randomly approached to fill out a questionnaire. A sample size of 530 students was collected and data was analyzed using SPSS 20 software and chi square tests for significance. Results: Of the 530 students interviewed, 361(68.1%) and 169(31.9%) were identified as medical and non-medical students respectively. Significantly greater knowledge on modes of transmission were noted in medical students as well as overall levels of awareness of Hepatitis B virus, (p=0.001) and (p=0.003) respectively. Conclusion: Both medical and non-medical students showed a moderate level of awareness of Hepatitis B virus, its modes of transmission, treatment and preventive measures. Medical students showed an overall greater level of awareness.


2018 ◽  
Author(s):  
Jolynne Mokaya ◽  
Anna L McNaughton ◽  
Martin J Hadley ◽  
Apostolos Beloukas ◽  
Anna-Maria Geretti ◽  
...  

ABSTRACTInternational sustainable development goals for the elimination of viral hepatitis as a public health problem by 2030 highlight the pressing need to optimize strategies for prevention, diagnosis and treatment. Selected or transmitted resistance associated mutations (RAMs) and vaccine escape mutations (VEMs) in hepatitis B virus (HBV) may reduce the success of existing treatment and prevention strategies. These issues are particularly pertinent for many settings in Africa where there is high HBV prevalence and co-endemic HIV infection, but lack of robust epidemiological data and limited education, diagnostics and clinical care. The prevalence, distribution and impact of RAMs and VEMs in these populations are neglected in the current literature. We therefore set out to assimilate data for sub-Saharan Africa through a systematic literature review and analysis of published sequence data, and present these in an on-line database (https://livedataoxford.shinyapps.io/1510659619-3Xkoe2NKkKJ7Drg/). The majority of the data were from HIV/HBV coinfected cohorts. The commonest RAM was rtM204I/V, either alone or in combination with compensatory mutations, and identified in both reportedly treatment-naïve and treatment-experienced adults. We also identified the suite of mutations rtM204V/I + rtL180M + rtV173L, that has been associated with vaccine escape, in over 1/3 of cohorts. Although tenofovir has a high genetic barrier to resistance, it is of concern that emerging data suggest polymorphisms that may be associated with resistance, although the precise clinical impact of these is unknown. Overall, there is an urgent need for improved diagnostic screening, enhanced laboratory assessment of HBV before and during therapy, and sustained roll out of tenofovir in preference to lamivudine alone. Further data are needed in order to inform population and individual approaches to HBV diagnosis, monitoring and therapy in these highly vulnerable settings.Author’s summaryThe Global Hepatitis Health Sector Strategy is aiming for the elimination of viral hepatitis as a public health threat by 2030. However, mutations associated with drug resistance and vaccine escape may reduce the success of existing treatment and prevention strategies. In the current literature, the prevalence, distribution and impact of hepatitis B virus (HBV) mutations in many settings in Africa are neglected, despite the high prevalence of HBV and co-endemic HIV infection. This systematic review describes the frequency, prevalence and co-occurrence of mutations associated with HBV drug resistance and vaccine escape mutations in Africa. The findings suggest a high prevalence of these mutations in some populations in sub-Saharan Africa. Scarce resources have contributed to the lack of HBV diagnostic screening, inconsistent supply of drugs, and poor access to clinical monitoring, all of which contribute to drug and vaccine resistance. Sustainable long-term investment is required to expand consistent drug and vaccine supply, to provide screening to diagnose infection and to detect drug resistance, and to provide appropriate targeted clinical monitoring for treated patients.


Author(s):  
Philippa C. Matthews

This chapter consists of short notes, diagrams, maps, and tables to summarize RNA viruses that are significant causes of disease in the tropics and subtropics. This includes measles, polio, hepatitis A, C, and E viruses, rabies, arboviruses, and viral haemorrhagic fevers. The chapter also includes sections on important retroviruses, HIV, and human T-lymphotropic virus. For ease of reference, each topic is broken down into sections, including classification, epidemiology, microbiology, pathophysiology, clinical syndromes, diagnosis, treatment, and prevention.


Author(s):  
Philippa C. Matthews

This chapter consists of short notes, diagrams, and tables to summarize Gram-negative organisms that are significant causes of disease in the tropics and subtropics. This includes Escherichia coli, Shigella, and Salmonella species (including typhoid and paratyphoid), Brucella, melioid, Campylobacter, and meningococci. For ease of reference, each topic is broken down into sections, including classification, epidemiology, microbiology, pathophysiology, clinical syndromes, diagnosis, treatment, and prevention.


2010 ◽  
Vol 84 (24) ◽  
pp. 12824-12831 ◽  
Author(s):  
Megan L. Maguire ◽  
Daniel D. Loeb

ABSTRACT Hepadnaviruses are DNA viruses that are found in several mammalian and avian species. These viruses replicate their genome through reverse transcription of an RNA intermediate termed pregenomic RNA (pgRNA). pgRNA is reverse transcribed by the viral polymerase into a minus-strand DNA, followed by synthesis of the plus-strand DNA. There are multiple cis-acting sequences that contribute to the synthesis of minus-strand DNA for human hepatitis B virus (HBV). Less is known about the cis-acting sequences of avian hepadnaviruses that contribute to synthesis of minus-strand DNA. To identify cis-acting sequences of duck hepatitis B virus (DHBV) and heron hepatitis B virus (HHBV), we analyzed variants containing 200-nucleotide (nt) deletions. Most variants of DHBV synthesized minus-strand DNA to 50 to 100% of the wild-type (WT) level, while two variants synthesized less than 50%. For HHBV, most variants synthesized minus-strand DNA to less than 50% the WT level. These results differ from those for HBV, where most of the genome can be removed with little consequence. HBV contains a sequence, φ, that contributes to the synthesis of minus-strand DNA. It has been proposed that DHBV has an analogous sequence. We determined that the proposed φ sequence of DHBV does not contribute to the synthesis of minus-strand DNA. Finally, we found that the DR2 sequence present in all hepadnaviruses is important for synthesis of minus-strand DNA in both DHBV and HHBV but not in HBV. These differences in cis-acting sequences suggest that the individual hepadnaviruses have evolved differences in their mechanisms for synthesizing minus-strand DNA, more so than for other steps in replication.


Author(s):  
Philippa C. Matthews

This chapter consists of short notes, diagrams, and tables to summarize Gram-positive organisms that are significant causes of disease in the tropics and subtropics. This includes anthrax, tetanus, clostridial infections, diphtheria, and streptococci. For ease of reference, each topic is broken down into sections, including classification, epidemiology, microbiology, pathophysiology, clinical syndromes, diagnosis, treatment, and prevention.


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