Genetic Diversity of Circulating Rotavirus Strains in Tanzania Prior to the Introduction of Vaccination

Background

Tanzania currently rolls out vaccination against rotavirus-diarrhea, a major cause of child illness and death. As the vaccine covers a limited number of rotavirus variants, this study describes the molecular epidemiology of rotavirus among children under two years in Dar es Salaam, Tanzania, prior to implementation of vaccination.

Methods

Stool specimens, demographic and clinical information, were collected from 690 children admitted to hospital due to diarrhea (cases) and 545 children without diarrhea (controls) during one year. Controls were inpatient or children attending child health clinics. Rotavirus antigen was detected using ELISA and positive samples were typed by multiplex semi-nested PCR and sequencing.

Results

The prevalence of rotavirus was higher in cases (32.5%) than in controls (7.7%, P<0.001). The most common G genotypes were G1 followed by G8, G12, and G4 in cases and G1, G12 and G8 in controls. The Tanzanian G1 variants displayed 94% similarity with the Rotarix vaccine G1 variant. The commonest P genotypes were P[8], P[4] and P[6], and the commonest G/P combination G1 P[8] (n = 123), G8 P[4] and G12 P[6]. Overall, rotavirus prevalence was higher in cool (23.9%) than hot months (17.1%) of the year (P = 0.012). We also observed significant seasonal variation of G genotypes. Rotavirus was most frequently found in the age group of four to six months. The prevalence of rotavirus in cases was lower in stunted children (28.9%) than in non-stunted children (40.1%, P = 0.003) and lower in HIV-infected (15.4%, 4/26) than in HIV-uninfected children (55.3%, 42/76, P<0.001).

Conclusion

This pre-vaccination study shows predominance of genotype G1 in Tanzania, which is phylogenetically distantly related to the vaccine strains. We confirm the emergence of genotype G8 and G12. Rotavirus infection and circulating genotypes showed seasonal variation. This study also suggests that rotavirus may not be an opportunistic pathogen in children infected with HIV.     

Household Transmission of Rotavirus in a Community with Rotavirus Vaccination in Quininde,Ecuador

Background

We studied the transmission of rotavirus infection in households in peri-urban Ecuador in the vaccination era.

Methods

Stool samples were collected from household contacts of child rotavirus cases, diarrhea controls and healthy controls following presentation of the index child to health facilities. Rotavirus infection status of contacts was determined by RT-qPCR. We examined factors associated with transmissibility (index-case characteristics) and susceptibility (household-contact characteristics).

Results

Amongst cases, diarrhea controls and healthy control household contacts, infection attack rates (iAR) were 55%, 8% and 2%, (n = 137, 130, 137) respectively. iARs were higher from index cases with vomiting, and amongst siblings. Disease ARs were higher when the index child was <18 months and had vomiting, with household contact <10 years and those sharing a room with the index case being more susceptible. We found no evidence of asymptomatic infections leading to disease transmission.

Conclusion

Transmission rates of rotavirus are high in households with an infected child, while background infections are rare. We have identified factors associated with transmission (vomiting/young age of index case) and susceptibility (young age/sharing a room/being a sibling of the index case). Vaccination may lead to indirect benefits by averting episodes or reducing symptoms in vaccinees.     

Predominance of Norovirus and Sapovirus in Nicaragua after Implementation of Universal Rotavirus Vaccination

Background

Despite significant reduction of rotavirus (RV) infections following implementation of RotaTeq vaccination in Nicaragua, a large burden of patients with diarrhea persists.

Methods

We conducted a community- and hospital-based study of the burden of RV, norovirus (NV) and sapovirus (SV) infections as cause of sporadic acute gastroenteritis (GE) among 330 children ≤ 5 years of age between September 2009 and October 2010 in two major cities of Nicaragua with a RotaTeq coverage rate of 95%.

Results

We found that NV, SV and RV infections altogether accounted for 45% of cases of GE. Notably, NV was found in 24% (79/330) of the children, followed by SV (17%, 57/330) and RV (8%, 25/330). The detection rate in the hospital setting was 27%, 15% and 14% for NV, SV and RV respectively, whereas in the community setting the detection rate of RV was < 1%. Among each of the investigated viruses one particular genogroup or genotype was dominant; GII.4 (82%) for NV, GI (46%) for SV and G1P[8] (64%) in RV. These variants were also found in higher proportions in the hospital setting compared to the community setting. The GII.4.2006 Minerva strain circulating globally since 2006 was the most common among genotyped NV in this study, with the GII.4-2010 New Orleans emerging in 2010.

Conclusions

This study shows that NV has become the leading viral cause of gastroenteritis at hospital and community settings in Nicaragua after implementation of RV vaccination.     

Speech Defects in Children Aged 7 Years: A National Study

A series of screening procedures applied on a national scale by doctors, teachers, and health visitors showed that between 10% and 13% of British 7-year-old children born in one week in 1958 were reported as having an appreciable degree of speech impairment. Between 1% and 2% had a marked speech defect though hearing normally. This latter group of speech-defective children were more often male and of poor family background, and more were born towards the end of a long family. They were often at a disadvantage educationally and had more clumsiness and defects of vision and visuomotor co-ordination than the rest of the sample. The methods used for screening provided a reliable guide in the selection of children who require further investigation.     

Evaluation of the Intussusception Risk after Pentavalent Rotavirus Vaccination in Finnish Infants

Background

An association between rotavirus immunisation and intussusception (IS) has been suggested with present rotavirus vaccines in post-licensure studies. In Finland, rotavirus vaccination programme was implemented in September 2009 using a 2, 3, and 5 months schedule with the pentavalent rotavirus vaccine. By the end of 2013, it is estimated that 719 000 rotavirus vaccine doses have been given in the national programme of which 240 000 were first doses. Nationwide register allows us to evaluate the association between rotavirus vaccination and IS.

Methods and Materials

Cases of IS diagnosed during 1999–2013 were identified from National Hospital Discharge Register. All cases under 250 days of age diagnosed during 2009–2013 were confirmed by reviewing medical charts. Self-controlled case-series method was used to assess the risk of IS during 1–21 days compared to 22–42 days post vaccination.

Findings

In register data the relative incidence of IS at 2 months of age between the post and pre vaccination era was 9.1 (95%CI 2.0–84.3). We identified 22 verified cases with date of admission less than 43 days after any of the three rotavirus vaccine doses. The incidence of IS in the risk period after the 1st dose relative to the control period was 2.0 (95% CI 0.5–8.4; p = 0.34.) Number of excess IS cases per 100 000 first vaccine doses was therefore estimated to be 1.04 (95% CI 0.0–2.5), i.e. one additional IS case per 96 000 first doses of rotavirus vaccine (95% CI 54 600 to ∞). There was no risk detected after 2nd and 3rd doses.

Conclusion

The finding is in line with the recent published estimates. The benefits of rotavirus immunisation programme outweigh possible small risks of intussusception.     

Group A Rotavirus in Sewage Samples from Barcelona and Cairo: Emergence of Unusual Genotypes

The presence of rotavirus strains in sewage samples from Cairo, Egypt (November 1998 to October 1999), and Barcelona, Spain (November 1998 to December 2002), was investigated by using a generic molecular detection method based on amplification of a VP6 gene fragment. Overall, 85.7 and 66.9% of the sewage samples from Cairo and Barcelona, respectively, were positive. Positive samples were characterized further, and VP7 and VP4 genotypes were determined. Although 30% of the positive samples from Cairo were G untypeable, the distribution of G types in the positive samples was 69.6% G1, 13% G3, 8.7% G4, and 8.7% G9. The percentage of untypeable samples was much higher for the Barcelona samples (56.5%), and the distribution in the positive samples was 56.4% G1, 31.5% G3, 6% G9, 4% G2, and 2% G5. When the P types were examined, 26.7% of the positive samples from Cairo were untypeable, and the distribution of types in the positive samples was 53.3% P[8], 30% P[6], and 16.6% P[4]. In Barcelona, 27.2% of the samples were P untypeable, and the frequencies of the types detected were 49.7% P[8], 37.2% P[4], 8.8% P[6], and 4.2% P[9]. The distribution for strains from Cairo was 38.5% P[8]G1, 27% P[6]G1, 11.5% P[4]G1, 11.5% P[8]G3, 7.7% P[6]G4, and 3.8% P[8]G9. Strikingly, equivalent frequencies of common and uncommon strains were observed for Barcelona samples, and the distribution was 38.8% P[8]G1, 30.6% P[4]G1, 11.6% P[8]G3, 6.6% P[4]G3, 5.8% P[6]G1, 1.6% P[6]G3, 1.6% P[9]G1, 0.8% P[4]G2, 0.8% P[6]G9, 0.8% P[8]G9, and 0.8% P[8]G5. Additionally, two P[−]G5 strains were isolated in Barcelona, and the porcine or human origin of these strains was unclear. Rotavirus variability exhibited not only a geographic pattern but also a temporal pattern.     

轮状病毒VP7基因的克隆与表达

应用聚合酶链式反应技术(PCR)扩增轮状病毒VP7基因,并将其克隆到pMD18-T simple载体上,对重组子进行PCR检测和限制性内切酶分析,并测定DNA全序列。结果显示,克隆片段全长为981 bp。将轮状病毒VP7基因定向的克隆到原核表达载体pET-32a启动子下游,构建原核表达载体pET-32aVP7。将质粒pET-32aVP7转化Transetta表达菌株进行诱导表达,裂解菌体细胞抽提蛋白质进行SDS-PAGE。结果表明,轮状病毒壳蛋白VP7基因在Transetta表达菌株内得到成功表达。     

Circulating Antibody Response in BCG Vaccination,Tuberculous Infection and Sarcoidosis

The bentonite flocculation test was used to differentiate antibodies formed by BCG vaccination from those produced by infections with virulent tubercle bacilli. Of 116 BCG-vaccinated nurses, only two (1.7%) showed antibody titres higher (1:128) than the threshold titre of 1:64 established for tuberculous patients.The bentonite test was also used to follow the course of infection in 54 patients with tuberculosis. A good correlation was found between the clinical course of the disease and O.T.-bentonite titres on repeated serological testing.Tuberculosis-like antibodies were demonstrated in sarcoidosis patients. These antibodies, however, are globulins (7S), in contrast to the macroglobulins (19S) found in tuberculous patients.     

Skin Vaccination against Rotavirus Using Microneedles: Proof of Concept in Gnotobiotic Piglets

Live-attenuated oral rotavirus (RV) vaccines have lower efficacy in low income countries, and additionally are associated with a rare but severe adverse event, intussusception. We have been pursuing the development of an inactivated rotavirus vaccine (IRV) using the human rotavirus strain CDC-9 (G1P[8]) through parenteral immunization and previously demonstrated dose sparing and enhanced immunogenicity of intradermal (ID) unadjuvanted IRV using a coated microneedle patch in comparison with intramuscular (IM) administration in mice. The aim of this study was to evaluate the immune response and protection against RV infection and diarrhea conferred by the administration of the ID unadjuvanted IRV using the microneedle device MicronJet600^® in neonatal gnotobiotic (Gn) piglets challenged with virulent Wa G1P[8] human RV. Three doses of 5 μg IRV when administered intradermally and 5 μg IRV formulated with aluminum hydroxide [Al(OH)₃] when administered intramuscularly induced comparable rotavirus-specific antibody titers of IgA, IgG, IgG avidity index and neutralizing activity in sera of neonatal piglets. Both IRV vaccination regimens protected against RV antigen shedding in stools, and reduced the cumulative diarrhea scores in the piglets. This study demonstrated that the ID and IM administrations of IRV are immunogenic and protective against RV-induced diarrhea in neonatal piglets. Our findings highlight the potential value of an adjuvant sparing effect of the IRV ID delivery route.     

Cost-Effectiveness Analysis of Universal Vaccination of Adults Aged 60 Years with 23-Valent Pneumococcal Polysaccharide Vaccine versus Current Practice in Brazil

Objective

To evaluate the cost-effectiveness of introducing universal vaccination of adults aged 60 years with the 23-valent pneumococcal polysaccharide vaccine (PPV23) into the National Immunization Program (NIP) in Brazil.

Methods

Economic evaluation using a Markov model to compare two strategies: (1) universal vaccination of adults aged 60 years with one dose of PPV23 and 2) current practice (vaccination of institutionalized elderly and elderly with underlying diseases). The perspective was from the health system and society. Temporal horizon was 10 years. Discount rate of 5% was applied to costs and benefits. Clinical syndromes of interest were invasive pneumococcal disease (IPD) including meningitis, sepsis and others and pneumonia. Vaccine efficacy against IPD was obtained from a meta-analysis of randomized control trials and randomized studies, whereas vaccine effectiveness against pneumonia was obtained from cohort studies. Resource utilization and costs were obtained from the Brazilian Health Information Systems. The primary outcome was cost per life year saved (LYS). Univariate and multivariate sensitivity analysis were performed.

Results

The universal vaccination strategy avoided 7,810 hospitalizations and 514 deaths, saving 3,787 years of life and costing a total of USD$31,507,012 and USD$44,548,180, respectively, from the health system and societal perspective. The universal immunization would result in ICERs of USD$1,297 per LYS, from the perspective of the health system, and USD$904 per LYS, from the societal perspective.

Conclusion

The results suggest that universal vaccination of adults aged 60 years with the 23-valent pneumococcal polysaccharide vaccine (PPV23) is a very cost-effective intervention for preventing hospitalization and deaths for IPD and pneumonia is this age group in Brazil.     

Forecasting Temporal Dynamics of Cutaneous Leishmaniasis in Northeast Brazil

Introduction

Cutaneous leishmaniasis (CL) is a vector-borne disease of increasing importance in northeastern Brazil. It is known that sandflies, which spread the causative parasites, have weather-dependent population dynamics. Routinely-gathered weather data may be useful for anticipating disease risk and planning interventions.

Methodology/Principal Findings

We fit time series models using meteorological covariates to predict CL cases in a rural region of Bahía, Brazil from 1994 to 2004. We used the models to forecast CL cases for the period 2005 to 2008. Models accounting for meteorological predictors reduced mean squared error in one, two, and three month-ahead forecasts by up to 16% relative to forecasts from a null model accounting only for temporal autocorrelation.

Significance

These outcomes suggest CL risk in northeastern Brazil might be partially dependent on weather. Responses to forecasted CL epidemics may include bolstering clinical capacity and disease surveillance in at-risk areas. Ecological mechanisms by which weather influences CL risk merit future research attention as public health intervention targets.     

Erythrocytary Zinc and the Infant Growth Profile in Northeast Brazil

This study evaluated nutritional status linked to zinc levels in 239 randomly selected children at crèches in Teresina, Brazil, aged 3 to 6. Blood samples were collected after fasting of 10 h. Erythrocytary zinc levels were determined through flame atomic absorption spectrophotometry. Zinc deficiency was determined as below 40 µg Zn/g Hb. Infant linear growth was evaluated measuring weight and height, and nutritional status by height/age, weight/height, and weight/age indices, expressed as Z scores, in line with the National Center for Health Statistics. The mean zinc concentration was 35.50?±?10.95 µg Zn/g Hb. Zinc distribution in the 10, 50, 75, and 90 percentiles was 24.73 µg Zn/g Hb, 35.45 µg Zn/g Hb, 40.73 µg Zn/g Hb and 52.77 µg Zn/g Hb, respectively. Based on this distribution, normal values were found only from the 75th percentile and above. Since the cutoff point adopted was 40 µg Zn/g Hb, the prevalence of zinc deficiency was 74.3%. As for growth profile, 8.4% were chronically malnourished, although the statistical association between linear impairment and nutritional status regarding zinc was insignificant. The study revealed that an important segment of the infant population was mineral deficient; however, the degree of deficiency did not influence growth profiles.     

我国人轮状病毒不同基因型NSP4的致病性研究

对我国轮状病毒流行株NSP4基因变异特点的分析表明,NSP4基因主要可分为Wa组和Kun组,在Wa组内可形成三个亚组,形成了4种NSP4基因型.为了进一步阐明人轮状病毒流行株NSP4基因变异与其致病性变化是否存在联系,我们首先利用杆状病毒载体对NSP4蛋白进行表达,获得了对应4种不同NSP4基因型的重组杆状病毒rvBac97B6,rvBac97S34,rvBac97S36和rvBac97SZ8.用这些病毒感染Sf-9细胞后,检测细胞内Ca2+浓度的变化,发现与野生型杆状病毒感染细胞相比,重组病毒感染细胞内的Ca2+浓度显著升高,但各个重组病毒之间无显著性差异.在此基础上,我们进一步在E.coli中分别表达纯化了代表Wa和Kun基因分组的97S34和97SZ8流行株的NSP4.分别用纯化的重组NSP4蛋白攻击乳鼠后,发现不同基因型的NSP4蛋白的致腹泻活性没有明显差异,这种作用可被NSP4抗体拮抗,但这种拮抗作用存在基因型特异性.上述结果表明人轮状病毒流行株NSP4氨基酸序列间的变异并没有使其钙调节及致腹泻能力产生改变,在致腹泻作用中发挥关键作用(或决定性作用)的氨基酸位点在不同NSP4基因型间可能是相对保守的.针对NSP4抗体的有效性也为新型轮状病毒疫苗和药物研究提供了线索.     

我国人轮状病毒不同基因型NSP4的致病性研究

对我国轮状病毒流行株NSP4基因变异特点的分析表明,NSP4基因主要可分为Wa组和Kun组,在Wa组内可形成三个亚组,形成了4种NSP4基因型。为了进一步阐明人轮状病毒流行株NSP4基因变异与其致病性变化是否存在联系,我们首先利用杆状病毒载体对NSP4蛋白进行表达,获得了对应4种不同NSP4基因型的重组杆状病毒rvBac97B6,rvBac97S34,rvBac97S36和rvBac97SZ8。用这些病毒感染Sf9细胞后,检测细胞内Ca2 浓度的变化,发现与野生型杆状病毒感染细胞相比,重组病毒感染细胞内的Ca2 浓度显著升高,但各个重组病毒之间无显著性差异。在此基础上,我们进一步在E.coli中分别表达纯化了代表Wa和Kun基因分组的97S34和97SZ8流行株的NSP4。分别用纯化的重组NSP4蛋白攻击乳鼠后,发现不同基因型的NSP4蛋白的致腹泻活性没有明显差异,这种作用可被NSP4抗体拮抗,但这种拮抗作用存在基因型特异性。上述结果表明人轮状病毒流行株NSP4氨基酸序列间的变异并没有使其钙调节及致腹泻能力产生改变,在致腹泻作用中发挥关键作用(或决定性作用)的氨基酸位点在不同NSP4基因型间可能是相对保守的。针对NSP4抗体的有效性也为新型轮状病毒疫苗和药物研究提供了线索。     

Soil bacterial diversity in degraded and restored lands of Northeast Brazil

Land degradation deteriorates biological productivity and affects environmental, social, and economic sustainability, particularly so in the semi-arid region of Northeast Brazil. Although some studies exist reporting gross measures of soil microbial parameters and processes, limited information is available on how land degradation and restoration strategies influence the diversity and composition of soil microbial communities. In this study we compare the structure and diversity of bacterial communities in degraded and restored lands in Northeast Brazil and determine the soil biological and chemical properties influencing bacterial communities. We found that land degradation decreased the diversity of soil bacteria as indicated by both reduced operational taxonomic unit (OTU) richness and Shannon index. Soils under native vegetation and restoration had significantly higher bacterial richness and diversity than degraded soils. Redundancy analysis revealed that low soil bacterial diversity correlated with a high respiratory quotient, indicating stressed microbial communities. By contrast, soil bacterial communities in restored land positively correlated with high soil P levels. Importantly, however, we found significant differences in the soil bacterial community composition under native vegetation and in restored land, which may indicate differences in their functioning despite equal levels of bacterial diversity.     

Effect of Measles Vaccination on Incidence of Measles in the Community

A study of the effect of measles vaccination on the incidence of the disease in eight separate areas of England and Wales was begun in 1966. It showed an inverse association between the proportion of children vaccinated and the incidence of measles in the area in the following year, but measles epidemics occurred in several of the areas in subsequent years, despite continuing vaccinations.Measles vaccination was introduced on a large scale in Britain in 1968. Analysis of the notification and vaccination statistics shows that the vaccination of about 10% of the child population (under 15 years) in 1968 sufficed to “replace” the measles epidemic which had been expected in the period October 1968 to September 1969 by a low incidence of the disease, typical of that in previous “interepidemic” years. Further, the effect of the vaccinations was to prevent the development of natural measles in susceptible unvaccinated children as well as in the vaccinated subjects. Thus the number of immune subjects in the community was increased by the vaccinations, but as a result there was a reduction in the number of subjects who acquired immunity from natural measles. These opposed results can therefore explain why vaccination may be effective in the community for only a year or two, though vaccination protects the individual for much longer.It is estimated that a continuing vaccination rate of 40 to 50% of the children born each year would be necessary to replace the regular biennial measles epidemics in Britain by a continuous endemic incidence, and might perhaps lead to the disappearance of the disease without a further major epidemic, but that a continuing vaccination rate of 80 to 90% of children born each year would then be necessary to prevent its reintroduction. The long-term control of measles by vaccination will thus probably prove more difficult than for any other infectious disease.     

Two‐step vegetation response to enhanced precipitation in Northeast Brazil during Heinrich event 1

High resolution palynological and geochemical data of sediment core GeoB 3910‐2 (located offshore Northeast Brazil) spanning the period between 19 600 and 14 500 calibrated year bp (19.6–14.5 ka) show a land‐cover change in the catchment area of local rivers in two steps related to changes in precipitation associated with Heinrich Event 1 (H1 stadial). At the end of the last glacial maximum, the landscape in semi‐arid Northeast Brazil was dominated by a very dry type of caatinga vegetation, mainly composed of grasslands with some herbs and shrubs. After 18 ka, considerably more humid conditions are suggested by changes in the vegetation and by C_org and C/N data indicative of fluvial erosion. The caatinga became wetter and along lakes and rivers, sedges and gallery forest expanded. The most humid period was recorded between 16.5 and 15 ka, when humid gallery (and floodplain) forest and even small patches of mountainous Atlantic rain forest occurred together with dry forest, the latter being considered as a rather lush type of caatinga vegetation. During this humid phase erosion decreased as less lithogenic material and more organic terrestrial material were deposited on the continental slope of northern Brazil. After 15 ka arid conditions returned. During the humid second phase of the H1 stadial, a rich variety of landscapes existed in Northeast Brazil and during the drier periods small pockets of forest could probably survive in favorable spots, which would have increased the resilience of the forest to climate change.     

Molecular Typing of Pathogenic Leptospira Serogroup Icterohaemorrhagiae Strains Circulating in China during the Past 50 Years

Background

Leptospirosis is one of the most important neglected tropical infectious diseases worldwide. Icterohaemorrhagiae has been throughout recent history, and still is, the predominant serogroup of this pathogen in China. However, very little in detail is known about the serovars or genotypes of this serogroup.

Methodology/Principal Findings

In this study, 120 epidemic strains from five geographically diverse regions in China collected over a 50 year period (1958~2008), and 8 international reference strains characterized by 16S rRNA sequencing and MLST analysis. 115, 11 and 2 strains were identified as L. interrogans, L. borgpetersenii, and L. kirschneri, respectively. 17 different STs were identified including 69 ST1 strains, 18 ST17, 18 ST128, 9 ST143 and 2 ST209. The remaining 12 strains belonged to 12 different STs. eBURST analysis demonstrated that, among the clonal complexes isolated (CCs), CC1 accounted for 73.3% (88/120) strains representing three STs: ST1, ST128 and ST98. ST1 was the most likely ancestral strain of this CC, followed by singleton CC17 (17/120) and CC143 (11/120). Further analysis of adding 116 serogroup Icterohaemorrhagiae strains in the MLST database and studies previously described using global eBURST analysis and MST dendrogram revealed relatively similar ST clustering patterns with five main CCs and 8 singletons among these 244 strains. CC17 was found to be the most prevalent clone of pathogenic Leptospira circulating worldwide. This is the first time, to our knowledge, that ST1 and ST17 strains were distributed among 4 distinct serovars, indicating a highly complicated relationship between serovars and STs.

Conclusions/Significance

Our studies demonstrated a high level of genetic diversity in the serogroup Icterohaemorrhagiae strains. Distinct from ST17 or ST37 circulating elsewhere, ST1 included in CC1, has over the past 50 years or so, proven to be the most prevalent ST of pathogenic leptospires isolated in China. Moreover, the complicated relationship between STs and serovars indicates an urgent need to develop an improved scheme for Leptospira serotyping.