Phylogeny of dengue virus type 3 circulating in Colombia between 2001 and 2007

Dengue virus type 3 (DENV-3) re-appeared in Colombia in 2001 after 23 years of apparent absence, in the state of Santander in the North-eastern region near to Venezuelan border. In 2002, the virus was isolated in the state of Valle del Cauca in the South-east region near to Ecuadorian/Peruvian border, and in the state of Antioquia in the North-east region near to Panama border. To gain insight into the molecular epidemiology of DENV-3 in Colombia, we sequenced the complete E gene of 21 isolates sampled in the period 2001–2007. Phylogenetic analyses revealed that Colombian strains seem to have been introduced from Venezuela, Ecuador and Peru, but not from Brazil, Argentina, Paraguay or Central America countries. This study also confirms previous report showing that Colombian isolates is closely related to DENV-3 genotype III.     

Dengue in travellers: applicability of the 1975–1997 and the 2009 WHO classification system of dengue fever

Objectives The aim of this study was to assess the applicability and benefits of the new WHO dengue fever guidelines in clinical practice, for returning travellers. Methods We compared differences in specificity and sensitivity between the old and the new guidelines for diagnosing dengue and assessed the usefulness in predicting the clinical course of the disease. Also, we investigated whether hypertension, diabetes or allergies, ethnicity or high age influenced the course of disease. Results In our setting, the old classification, compared with the new, had a marginally higher sensitivity for diagnosing dengue. The new classification had a slightly higher specificity and was less rigid. Patients with dengue who had warning signs as postulated in the new classification were admitted more often than those who had no warning signs (RR, 8.09 [1.80–35.48]). We did not find ethnicity, age, hypertension, diabetes mellitus or allergies to be predictive of the clinical course. Conclusions In our cohort of returned travellers, the new classification system did not differ in sensitivity and specificity from the old system to a clinically relevant degree. The guidelines did not improve identification of severe disease.     

2001-2016年广州市登革3型病毒E基因序列及系统进化树分析

目的 了解2001-2016年广州市登革3型病毒的流行情况,掌握毒株的进化情况和趋势。方法 将登革热确诊病例的血清用荧光PCR检测,阳性血清用C6/36细胞进行病毒分离,测定分离毒株的E基因序列,与NCBI的毒株序列相比较,利用Mega 4.0软件构建系统进化树。结果2001-2016年共分离到登革3型病毒24株,从基因型上分类属于基因亚型I、II、III和V型,基因亚型III在流行年份和分离毒株数上稍占优势。流行病学调查和序列分析均显示与东南亚国家流行的登革热相关度较高。结论 广州市登革3型病毒以输入为主,随着输入压力增大、基因亚型增多和转换,可能会使广州市登革热流行传播更为复杂,流行风险进一步增高。     

Investigation of a Chikungunya-like illness in Tirunelveli district, Tamil Nadu, India 2009-2010

Objective To identify the aetiological agent/s of an outbreak of chikungunya‐like illness with high morbidity and several fatalities in Tamil Nadu, India, 2009–2010. Methods Two hundred and seventeen serum samples were collected from the affected areas and screened for chikungunya virus (CHIKV), dengue virus (DENV) and Japanese encephalitis virus (JEV) IgM antibodies using MAC‐ELISA kits. A few selected samples were also tested for Ross River, Sindbis, and Murrey Valley viruses by RT‐PCR and Hantan virus by serology. Twelve acute serum and mosquito samples were processed for virus isolation in C6/36 cells. CHIKV isolate was characterised by RT‐PCR and sequencing. Results Diagnostic levels of IgM antibodies were detected in 107 (49.3%) CHIKV samples and 22 (10.1%) DENV samples. IgM antibodies against JEV were not detected (n = 46). Characterisation of the CHIKV isolate at genetic level demonstrated it as ECSA (E1: 226A). Thirty‐six selected samples were also negative for Ross River, Sindbis, Murrey Valley and Hantan viruses. Conclusion High prevalence of CHIKV IgM antibody positivity, clinical symptoms, virus isolation and the presence of vector mosquitoes clearly suggest CHIKV as the aetiological agent responsible for the outbreak.     

Dengue,chikungunya and Zika virus infections among Dutch travellers to Suriname: a prospective study during the introduction of chikungunya and Zika virus, 2014 to 2017

BackgroundSuriname, a country endemic for dengue virus (DENV), is a popular destination for Dutch travellers visiting friends and relatives and tourist travellers. Chikungunya and Zika virus (CHIKV, ZIKV) were introduced in 2014 and 2015, respectively. Data on infection risks among travellers are limited.AimWe aimed to prospectively study incidence rate (IR) and determinants for DENV, ZIKV and CHIKV infection in adult travellers to Suriname from 2014 through 2017.MethodsParticipants kept a travel diary and were tested for anti-DENV, anti-ZIKV and anti-CHIKV IgG antibodies (Euroimmun). Selected samples were subjected to an in-house DENV and ZIKV PRNT50. The IR (infections/1,000 person-months of travel) and IR ratio and determinants for infection were calculated.ResultsTravel-acquired infections were found in 21 of 481 participants: 18 DENV, four ZIKV and two CHIKV, yielding an IR_DENV of 47.0 (95% CI: 29.6–74.6), IR_ZIKV of 11.6 (95% CI: 4.4–31.0) and IR_CHIKV of 5.6 (95% CI: 1.4–22.2)/1,000 person-months. In nine DENV and three ZIKV infected participants, infections were PRNT50-confirmed, yielding a lower IR_DENV of 23.3 (95% CI: 12.1–44.8) and an IR_ZIKV of 8.4 (95% CI: 2.7–26.1) per 1,000 person-months. Tourist travel was associated with DENV infection. ZIKV and CHIKV infections occurred soon after their reported introductions.ConclusionsDespite an overestimation of serologically confirmed infections, Dutch travellers to Suriname, especially tourists, are at substantial risk of DENV infection. As expected, the risk of contracting ZIKV and CHIKV was highest during outbreaks. Cross-reaction and potential cross-protection of anti-DENV and -ZIKV antibodies should be further explored.     

The development of predictive tools for pre‐emptive dengue vector control: a study of Aedes aegypti abundance and meteorological variables in North Queensland,Australia

Objectives To describe the meteorological influences on adult dengue vector abundance in Australia for the development of predictive models to trigger pre‐emptive control operation. Methods Multiple linear regression analyses were performed using meteorological data and female Aedes aegypti collection data from BG‐Sentinel Mosquito traps placed at 11 monitoring sites in Cairns, north Queensland. Results Considerable regression coefficients (R² = 0.64 and 0.61) for longer‐ and shorter‐term factor models respectively were derived. Longer‐term factors significantly associated with abundance of adult vectors were mean minimum temperature (lagged 6 month) and mean daily temperature (lagged 4 month), explaining the predictable increase in abundance during the wet season. Factors explaining fluctuation in abundance in the shorter term were mean relative humidity over the previous 2 week and current daily average temperature. Rainfall variables were not found to be strong predictors of A. aegypti abundance in either longer‐ or shorter‐term models. Conclusions The implications of these findings for the development of useful predictive models for vector abundance risks are discussed. Such models can be used to guide the application of pre‐emptive dengue vector control, and thereby enhance disease management.     

A population‐based study of how children are exposed to saliva in KwaZulu‐Natal Province,South Africa: implications for the spread of saliva‐borne pathogens to children

Objectives In sub‐Saharan Africa, many viral infections, including Epstein–Barr virus, cytomegalovirus, Kaposi’s sarcoma‐associated herpesvirus and hepatitis B are acquired in childhood. While saliva is an important transmission conduit for these viruses, little is known about how saliva is passed to African children. We endeavoured to identify the range and determinants of acts by which African children are exposed to saliva. Methods To identify the range of acts by which African children are exposed to saliva, we conducted focus groups, semi‐structured interviews and participant observations in an urban and a rural community in South Africa. To measure the prevalence and determinants of the identified acts, we administered a questionnaire to a population‐based sample of caregivers. Results We identified 12 caregiving practices that expose a child’s oral–respiratory mucosa, cutaneous surfaces or anal–rectal mucosa to saliva. Several acts were heretofore not described in the contemporary literature (e.g., caregiver inserting finger lubricated with saliva into child’s rectum to relieve constipation). Among 896 participants in the population‐based survey, many of the acts were commonly practised by all respondent types (mothers, fathers, grandmothers and siblings). The most common were premastication of food, sharing sweets and premastication of medicinal plants that are spit onto a child’s body. Conclusions African children are exposed to saliva through a variety of acts, practised by a variety of caregivers, with no single predominant practice. This diversity poses challenges for epidemiologic work seeking to identify specific saliva‐passing practices that transmit viruses. Most acts could be replaced by other actions and are theoretically preventable.