Tracing Back the Source of an Outbreak of Salmonella Typhimurium; National Outbreak Linked to the Consumption of Raw and Undercooked Beef Products, the Netherlands, October to December 2015

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Introduction. On 23 October 2015, six related cases with gastroenteritis called the Netherlands Food and Consumer Product Safety Authority. They suspected filet américain, a raw beef spread, to be the source of infection. Leftovers and stool samples tested positive for Salmonella Typhimurium. Multiple locus variable-number of tandem repeat analysis (MLVA) revealed a MLVA pattern (02-23-08-08-212), which had not been detected in the Netherlands before. Concomitantly, an increase of this MLVA type was observed in the national Salmonella surveillance, amounting to 46 cases between 26 October and 9 December.

Methods. To investigate whether filet américain or an alternative (related) source could  be linked to surveillance-reported cases, cases (n=38) were invited to complete a questionnaire and upstream source tracing to map the food supply chain was initiated.

Results. Rapid interdisciplinary action resulted in identification of a contaminated 46-ton batch of beef distributed via a Dutch deboning plant as the likely source of infection. In total, 24/29 respondents (83%) could be linked to the incriminated batch of beef products (predominantly filet américain and minced beef).

Discussion. Repeated identification of raw meat products as a source of infection emphasizes the importance of awareness of the risk of infection when handling or consuming these products. Improved measures and procedures on product labelling, pre-treatment or product testing should be considered.

The 2015 Outbreak of Severe Influenza in Kashmir, North India: Emergence of a New Clade of A/H1n1 Influenza Virus

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HA phylogenetic analysis of 2015 isolates of A(H1N1)pdm09 . The tree consists of 2015 isolates from Pune, Delhi and compared with Srinager isolates .The astrix and underline isolates are from the fatal severe cases . The 2015-16 vaccine component is shown in red font. Srinager strains are in blue font. 2015 isolates belong to Clade 7 with clade specific A203T and D97N signature mutations

Introduction: Following the initial outbreak of A/H1N1pdm09, periodic resurgences of the virus, with variable morbidity and mortality, have been reported from various parts of India including the temperate Kashmir region of northern India. An outbreak of A/H1N1 was reported in early 2015 across India with a high morbidity and mortality. We studied patients during the outbreak in Kashmir.

Methods: Patients (n=1780, age 1 month to 90 years, median 35 years) presenting with acute respiratory illness to a tertiary care hospital in Srinagar, Kashmir from October 2014 to April 2015 were recruited. After clinical data recording, combined throat and nasal swabs were collected in viral transport medium and tested by real-time RT-PCR for influenza viruses. All influenza A positive samples were further subtyped using primers and probes for A/H1N1pdm09 and A/H3 whereas influenza B samples were further subtyped into B/Yamagata and B/Victoria lineages. Virus isolation, hemagglutination inhibition testing, sequencing and phylogenetic analysis was carried out using standard procedures. Testing for H275Y mutation was done to determine sensitivity to oseltamivir. All patients received symptomatic therapy and influenza positive patients were administered oseltamivir.

Results: Of the 1780 patients, 540 (30%) required hospitalization and 533 tested positive for influenza [influenza A=517(A/H1N1pdm09=437, A/H3N2=78 with co-infection of both in 2 cases); influenza B=16 (B/Yamgata=15)]. About 14% (n=254) had been vaccinated against influenza, having received the NH 2014-15 vaccine, 27 (11.3%) of these testing positive for influenza.  Sixteen patients, including 4 pregnant females, died due to multi-organ failure. HA sequencing depicted that 2015 isolates belonged to Clade 6B.1. No H275Y mutation was reported from A/H1N1 positives.

Conclusion: Resurgent outbreak of A/H1N1pdm09, with emergence of clade 6B.1, in 2014-15 resulted in high rate of hospitalizations, morbidity and mortality. Periodic resurgences and appearance of mutants emphasize continued surveillance so as to identify newer mutations with potential for outbreaks and severe outcomes.

The 2016-2017 Chikungunya Outbreak in Karachi

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Introduction: Chikungunya is an incipient disease, caused by Chikungunya virus (CHKV) that belongs to genus alphavirus of the family Togaviridae.

Materials and Methods: In this study, during an outbreak of CHKV in Dec 2016 in Karachi, Pakistan, samples were collected from patients presenting with fever, tiredness and pain in muscles and joints. Total 126 sera were tested for the presence of Chikungunya infection through ELISA and Real-time Reverse Transcriptase PCR assay.

Results and Discussion: This study showed that approx 79.4% samples were positive for CHKV. To our knowledge, this is the first reported outbreak from last decades in which the presence of CHKV is confirmed in Karachi while affecting such large no. of individuals.. Conclusion: CHKV diagnosis should be considered by the scientists and clinicians as a differential diagnosis in febrile patients, and appropriate control strategies must be adopted for its surveillance.

Identifying Areas at Greatest Risk for Recent Zika Virus Importation — New York City, 2016

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Introduction: The New York City Department of Health and Mental Hygiene sought to detect and minimize the risk of local, mosquito-borne Zika virus (ZIKV) transmission. We modeled areas at greatest risk for recent ZIKV importation, in the context of spatially biased ZIKV case ascertainment and no data on the local spatial distribution of persons arriving from ZIKV-affected countries.

Methods: For each of 14 weeks during June-September 2016, we used logistic regression to model the census tract-level presence of any ZIKV cases in the prior month, using eight covariates from static sociodemographic census data and the latest surveillance data, restricting to census tracts with any ZIKV testing in the prior month. To assess whether the model discriminated better than random between census tracts with and without recent cases, we compared the area under the receiver operating characteristic (ROC) curve for each week’s fitted model versus an intercept-only model applied to cross-validated data. For weeks where the ROC contrast test was significant at P < 0.05, we output and mapped the model-predicted individual probabilities for all census tracts, including those with no recent testing.

Results: The ROC contrast test was significant for 8 of 14 weekly analyses. No covariates were consistently associated with the presence of recent cases. Modeled risk areas fluctuated across these 8 weeks, with Spearman correlation coefficients ranging from 0.30 to 0.93, all P < 0.0001. Areas in the Bronx and upper Manhattan were in the highest risk decile as of late June, while as of late August, the greatest risk shifted to eastern Brooklyn.

Conclusion: We used observable characteristics of areas with recent, known travel-associated ZIKV cases to identify similar areas with no observed cases that might also be at-risk each week. Findings were used to target public education and Aedes spp. mosquito surveillance and control. These methods are applicable to other conditions for which biased case ascertainment is suspected and knowledge of how cases are geographically distributed is important for targeting public health activities.

Lessons Learnt from Epidemiological Investigation of Lassa Fever Outbreak in a Southwest State of Nigeria December 2015 to April 2016

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Introduction: An outbreak of Lassa Fever (LF) reported and confirmed in Ondo state, Southwest Nigeria in January 2016 was investigated. This paper provides the epidemiology of the LF and lessons learnt from the investigation of the outbreak.

Methods: The incidence management system (IMS) model was used for the outbreak coordination. Cases and deaths were identified through the routine surveillance system using standard definitions for suspected and confirmed cases and deaths respectively. Blood specimens collected from suspect cases were sent for confirmation at a WHO accredited laboratory. Active case search was intensified, and identified contacts of confirmed cases were followed up for the maximum incubation period of the disease. Other public health responses included infection prevention and control, communication and advocacy as well as case management. Data collected were analysed using SPSS 20, by time, place and persons and important lessons drawn were discussed.  

Results: We identified 90 suspected LF cases of which 19 were confirmed by the laboratory. More than half (52.6%) of the confirmed cases were females with majority (73.7%) in the age group ≥ 15 years. The Case Fatality Rate (CFR) of 63.2% among the laboratory-confirmed positive cases where 9 of 19 cases died, was significantly higher compared to the laboratory confirmed negative cases where 6 of the 65 cases died ( CFR; 8.5%) p ≤ 0.05. Two hundred and eighty-seven contacts of the confirmed cases were identified, out of which 267(93.0%) completed  the follow-up without developing any symptoms and 2 (0.7%) developed symptoms consistent with LF and were confirmed by the laboratory. More than half of the contacts were females (64.5%) with most of them (89.2%) in the age group ≥ 25 years.  

Discussion: One key lesson learnt from the investigation was that the confirmed cases were mainly primary cases; hence the needs to focus on measures of breaking the chain of transmission in the animal-man interphase during Lassa fever epidemic preparedness and response. In addition, the high case fatality rate despite early reporting and investigation suggested the need for a review of the case management policy and structure in the State. Key Words: Lassa fever, Outbreak Response, Incident Management System, Nigeria

Zika virus outbreak in Suriname, a report based on laboratory surveillance data

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Introduction : Since the identification of ZIKV in Brazil in May 2015, the virus has spread extensively throughout the Americas. Cases of ZIKV infection have been reported in Suriname since October 2, 2015.  Methods : A laboratory-based surveillance system was quickly implemented according to previous experience with the emergence of chikungunya. General practitioners and public health centers located in different districts of Suriname were asked to send blood samples from suspicious cases to Academic Hospital for molecular diagnosis of Zika virus infection. We investigated Zika-related laboratory data collected during surveillance and response activities to provide the first outbreak report in Suriname in terms of time, location and person. Results : A total of 791 molecularly confirmed cases were reported during a 48-week interval from October 2015 to August 2016. The majority of ZIKV-positive cases involved women between 20 and 39 years of age, reflecting concern about Zika infection during pregnancy. The outbreak peaked in mid-January and gradually spread from the district of Paramaribo to western coastal areas. Discussion : This report provides a simple and comprehensive description of the outbreak in Suriname and demonstrates the utility of laboratory data to highlight the spatiotemporal dynamics of the outbreak in that country.

The First Outbreak of Autochthonous Zika Virus in Sabah, Malaysian Borneo

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Background: Zika virus (ZIKV) infection is a public health concern. The first ZIKV outside Africa was detected in mosquito in Malaysia. More than six decades ago, serological surveys indicated the presence of human infection with ZIKV in the Malaysian Borneo state of Sabah. It has also been demonstrated that orangutans in Sabah have antibodies against ZIKV. Several years ago, a case of human ZIKV infection was reported in a traveler who visited Sabah. Therefore, it is thought that ZIKV is endogenous to Sabah and is widely distributed.  During the recent global epidemic of ZIKV, the first autochthonous case and two subsequent autochthonous cases were detected in Sabah. Because ZIKV infection is mainly asymptomatic or mildly symptomatic, the extent of ZIKV infection in the population of Sabah is not known. Furthermore, the presence of ZIKV in vector mosquitoes and animals has not been investigated. Therefore, the present study was performed to analyze the outbreak cases of ZIKV infection and to determine their relationship with the burden of ZIKV infection in the local population, mosquitoes, and wild nonhuman primates in Sabah. 

Methods: Serum and urine samples were collected from two local patients with ZIKV infection, their household members, and those who resided within 400m of the patients’ residences. Serum samples were also collected from four wild Maca fascicularis. Mosquito samples, mostly female Aedes albopictus, were collected from 30 sites in Kota Kinabalu. The presence of ZIKV was assessed by RT-qPCR and RT-PCR. Phylogenetic analysis was performed using the neighbor-joining method.  

Results: Two cases of ZIKV infection were identified by reverse-transcription quantitative PCR (RT-qPCR) in residents of Kota Kinabalu, and the Taiwanese health authorities reported one case in an individual who visited Kota Kinabalu during the study period. All household members of both local patients and people living within a 400 m radius of the patients were negative for ZIKV. Furthermore, mosquitoes collected from the surroundings of the residences and places visited by the patients and four serum samples from M. fascicularis were also negative for ZIKV. A phylogenetic tree constructed using the nucleotide sequences of the envelope genes of ZIKV showed that the strains from Sabah formed a cluster with strains from Thailand and Cambodia, and belong to the Asian lineage. 

Conclusions: Our study revealed that ZIKVs in Sabah is of Asian lineage and are not related to the recent outbreak strains in the Americas and Singapore. ZIKV infection in Sabah is sporadic, possibly because of limited transmission of the virus. Further studies are needed to characterize the evolutionary history of ZIKV in Sabah to understand the epidemiology of this infection in Borneo.

A Psittacosis Outbreak among English Office Workers with Little or No Contact with Birds, August 2015

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Introduction: On 14th August 2015 an office manager informed Public Health England of five employees known to have been diagnosed with pneumonia over the previous three weeks. We investigated to establish whether an outbreak occurred and to identify and control the source of infection.

Methods: We undertook case finding for self-reported pneumonia cases at local businesses (July-August 2015). Clinical samples from a hospitalised case were tested for common respiratory pathogens, but returned negative results. Further testing confirmed Chlamydia psittaci infection in this case (serology and PCR).  We subsequently undertook C. psittaci testing for all cases, redefining them as confirmed (C. psittaci PCR or high antibody titre via serology) or probable (inconclusive C. psittaci serology). Twenty-eight day exposure histories informed descriptive epidemiological analysis. We conducted an environmental investigation at the office to identify potential sources of exposure.

Results: We identified six office workers with pneumonia; four met case definitions (three confirmed, one probable) with symptom onset between 29th July and 4th August 2015. Workplace was the only epidemiological link and only one case reported limited, indirect bird contact. Environmental investigations identified pigeons roosting near the office which were being fed by workers (none cases).

Discussion: This was a probable outbreak of psittacosis with no direct bird-to-human contact reported. Cases recovered after receiving appropriate antibiotics. Feeding of pigeons was stopped. A deep clean of office ventilation systems was conducted and workers were advised to avoid bird contact.  We hypothesised that indirect environmental exposure to infected pigeons was to the source of this outbreak. This work provides evidence that health professionals should consider psittacosis in the differential diagnosis of cases of severe or atypical respiratory illness even without overt bird contact.

Analyzing the Local Epidemiological Profile of Malaria Transmission in the Brazilian Amazon Between 2010 and 2015

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Introduction: Malaria still is a public health problem in the Americas. In 2015, Brazil accounted for 37% of all cases in the Americas, and of these cases, 99.5% were located in the Brazilian Amazon. Despite the mobilization of resources from the Brazilian National Plan for Malaria Control, too many municipalities have high transmission levels. The objective of this study is to evaluate the local epidemiological profile of malaria and its trend between 2010 and 2015 in the Brazilian Amazon. This study also aims to recognize the epidemiological differences in the local temporo-spatial dynamics of malaria.

Methods: Malaria data were stratified by the annual parasite incidence (API) over the six-year period and by municipality. We used the method of seasonal decomposition by Loess smoothing to capture trend, seasonal and irregular components. A generalized linear model was applied to quantify trends, and the Kruskal-Wallis Rank Sum was applied to test for seasonality significance.

Results: The malaria API declined by 61% from 2010 to 2015, and there was a 40% reduction of municipalities with high transmission (determined as an API higher than 50). In 2015, 9.4% of municipalities had high transmission and included 62.8% of the total cases. The time-series analyses showed different incidence patterns by region after 2012; several states have minimized the effect of the seasonality in their incidence rates, thus achieving low rates of incidence. There were 13 municipalities with sustained high transmission that have become the principal focus of malaria control; these municipalities contained 40% of the cases between 2013 and 2015.

Discussion: Brazil has achieved advances, but more sustained efforts are necessary to contain malaria resurgence. The use of malaria stratification has been demonstrated as a relevant tool to plan malaria programs more efficiently, and spatiotemporal analysis corroborates the idea that implementing any intervention in malaria should be stratified by time to interpret tendencies and by space to understand the local dynamics of the disease.

Health Information Needs and Health Seeking Behavior During the 2014-2016 Ebola Outbreak: A Twitter Content Analysis

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Introduction: For effective public communication during major disease outbreaks like the 2014-2016 Ebola epidemic, health information needs of the population must be adequately assessed. Through content analysis of social media data, like tweets, public health information needs can be effectively assessed and in turn provide appropriate health information to address such needs. The aim of the current study was to assess health information needs about Ebola, at distinct epidemic time points, through longitudinal tracking.

Methods: Natural language processing was applied to explore public response to Ebola over time from July 2014 to March 2015. A total 155,647 tweets (unique 68,736, retweet 86,911) mentioning Ebola were analyzed and visualized with infographics.

Results: Public fear, frustration, and health information seeking regarding Ebola-related global priorities were observed across time. Our longitudinal content analysis revealed that due to ongoing health information deficiencies, resulting in fear and frustration, social media was at times an impediment and not a vehicle to support health information needs. 

Discussion: Content analysis of tweets effectively assessed Ebola information needs. Our study also demonstrates the use of Twitter as a method for capturing real-time data to assess ongoing information needs, fear, and frustration over time.