Accurate Epidemiological Information Research Articles

Interlaboratory variability in screening for Bonamia ostreae, a protistan parasite of the European flat oyster Ostrea edulis.

The spread of the protozoan parasite Bonamia ostreae is of major concern to the European flat oyster Ostrea edulis industry. Many studies have looked at the sensitivity of individual methods available to screen for B. ostreae, but in this study, 3 separate laboratories examined 4 methods of diagnosis currently used routinely in laboratories: heart imprints, histology, polymerase chain reaction (PCR) and in situ hybridisation (ISH). The results were compared to estimate interlaboratory variability. Heart imprints and histology had the highest reproducibility amongst the 3 laboratories, with greatest agreement between detection of infected and uninfected individuals. PCR had the highest detection level in every laboratory. These positives were related to the presence of confirmed infections but also in unconfirmed infections, possibly due to the presence of traces of B. ostreae DNA in oysters where clinical infections were not observed. PCR, in combination with histology or ISH, provided the most reliable detection levels in every laboratory. Variation in results for PCR and ISH observed between laboratories may be due to the different protocols used by each laboratory for both methods. Overall, the findings from the 3 laboratories indicated that at least 2 methods, with fixed protocols, should be used for the accurate detection and determination of infection prevalence within a sample. This combination of methods would allow for a clearer and more precise diagnosis of B. ostreae, preventing further spread of the disease and providing more accurate detection levels and epidemiological information.

Estimating rheumatic fever incidence in New Zealand using multiple data sources

Rheumatic fever (RF) is an important public health problem in New Zealand (NZ). There are three sources of RF surveillance data, all with major limitations that prevent NZ generating accurate epidemiological information. We aimed to estimate the likely RF incidence using multiple surveillance data sources. National RF hospitalization and notification data were obtained, covering the periods 1988-2011 and 1997-2011, respectively. Data were also obtained from four regional registers: Wellington, Waikato, Hawke's Bay and Rotorua. Coded patient identifiers were used to calculate the proportion of individuals who could be matched between datasets. Capture-recapture analyses were used to calculate the likely number of true RF cases for the period 1997-2011. A range of scenarios were used to correct for likely dataset incompleteness. The estimated sensitivity of each data source was calculated. Patients who were male, Māori or Pacific, aged 5-15 years and met the Jones criteria, were most likely to be matched between national datasets. All registers appeared incomplete. An average of 113 new initial cases occurred annually. Sensitivity was estimated at 80% for the hospitalization dataset and 60% for the notification dataset. There is a clear need to develop a high-quality RF surveillance system, such as a national register. Such a system could link important data sources to provide effective, comprehensive national surveillance to support both strategy-focused and control-focused activities, helping reduce the incidence and impact of this disease. It is important to remind clinicians that RF cases do occur outside the well-characterized high-risk group.

Development of a Specimen-Sparing Multichannel Bead Assay to Detect Antiparasite IgG4 for the Diagnosis of Schistosoma and Wuchereria Infections on the Coast of Kenya

To better delineate the impact of parasitic coinfection in coastal Kenya, we developed a novel specimen-sparing bead assay using multiplex flow immunoassay (MFI) technology to simultaneously measure serum or plasma immunoglobulin G4 (IgG4) against Brugia malayi antigen (BMA) and Schistosoma haematobium soluble worm antigen (SWAP). Properties of the bead assay were estimated by latent class analysis using data from S. haematobium egg counts/filarial rapid diagnostic cards (RDTs), parasite-specific enzyme-linked immunosorbent assays (ELISAs), and the multichannel IgG4 assay. For schistosomiasis, the bead assay had an estimated sensitivity of 81% and a specificity of 45%, and it was more sensitive than ELISA or urine egg counts for diagnosing infection. For filariasis, it had a sensitivity of 86% and a specificity of 39%, and it was more sensitive than ELISA or RDT. Measuring antibody by MFI is feasible and may provide more accurate epidemiological information than current parasitological tests, especially in the setting of low-intensity infections.

The incidence of Parkinson's disease in the North-East of England

Parkinson's disease is a common disorder among older people. Accurate epidemiological information is essential to identify possible aetiological factors, plan health services and set priorities for medical research. to determine the incidence of idiopathic Parkinson's disease in a defined geographical area in the North-East of England. using a prospective, longitudinal design, we sought to identify every new case of Parkinson's disease arising in the Newcastle and Gateshead area in the North-East of England. The base population comprised 488 576 individuals and multiple sources of case ascertainment were employed. All the patients with newly diagnosed idiopathic Parkinson's disease or parkinsonism between 1 June 2009 and 31 May 2011 were invited to participate. Patients were examined by a specialist and followed longitudinally to permit diagnostic review. we identified 257 potential cases, of whom 181 had suspected idiopathic Parkinson's disease. After a follow-up period of 18 months, 155 patients retained a clinical diagnosis of probable Parkinson's disease. The mean age at diagnosis was 72.4 ± 10 years. The crude incidence of PD in Newcastle and Gateshead was 15.9 per 100 000 persons per year (95% CI: 13.4-18.4). Age-standardised to the European population the incidence of Parkinson's disease was 12.0 per 100 000 (95% CI: 10.1-14.0). We found a higher crude incidence among men 17.7 per 100 000 (95% CI: 14.0-21.4) than women 14.0 per 100 000 (95% CI: 10.7-17.4). in this prospective longitudinal study, the incidence rate of Parkinson's disease in North-East England is similar to that of other modern European and American studies.

Surveillance for enteric pathogens in a case-control study of acute diarrhea in Western Kenya

Acute diarrhea remains a major public health problem in East African nations such as Kenya. Surveillance for a broad range of enteric pathogens is necessary to accurately predict the frequency of pathogens and potential changes in antibiotic resistance patterns. Stool samples were collected from September 2009 to September 2011; 193 and 239 samples, from age-matched cases and asymptomatic controls, were collected, respectively, from Kericho and Kisumu District Hospitals in western Kenya. Bacterial pathogens were identified by conventional microbiological methods; antibiotic susceptibility of bacterial isolates was ascertained using the MicroScan WalkAway 40 Plus. An enzyme immunoassay kit was used to detect rotavirus, and ova and parasite examination was conducted by microscopy and an enzyme immunoassay. Rotavirus (10.2% and 10.5%) and Shigella (11% and 8%) were isolated significantly more often in the cases than the controls from Kericho and Kisumu District Hospitals respectively. The diarrheagenic Escherichia coli, Campylobacter jejuni and Salmonella were found most often in the cases while Giardia lamblia and Entamoeba histolytica/E. dispar were found more often in the controls. Most pathogens were isolated from children under 5 years old. More than 50% of the Shigella, Salmonella and diarrheagenic E. coli isolates were multidrug resistant to ampicillin, tetracycline and trimethoprim/sulfamethoxazole with several enteroaggregative and enterotoxigenic E. coli isolates producing extended-spectrum beta-lactamases. Accurate epidemiologic information on acute diarrheal illness in Kenya will be critical for augmenting existing diarrhea management policies in terms of treatment and to strengthen future community awareness and health promotion programs.

Outbreak analysis and typing of MRSA isolates by automated repetitive-sequence-based PCR in a region with multiple strain types causing epidemics

The usefulness and performance of repetitive-sequence-based polymerase chain reaction (rep-PCR), the DiversiLab system, in the epidemiological surveillance for methicillin-resistant Staphylococcus aureus (MRSA) strain typing was assessed. MRSA isolates from five distinct outbreaks with precise epidemiological data (n = 69) and from the culture collection of well-characterized MRSA strains (n = 132) consisting of 35 spa and 23 pulsed-field gel electrophoresis (PFGE) types were analyzed. The typing results of the DiversiLab system in outbreak analysis were compared to the spa and PFGE typing methods. The DiversiLab system proved to be a reliable tool for the rapid first-line typing of MRSA isolates, showing a good reliability in distinguishing MRSA strains in an area where several MRSA types were causing epidemics. This, however, required that the automatic clustering was combined with manual interpretation using the pattern overlay function when the strain types showing high similarity were clustered together. All outbreaks were distinguished with the DiversiLab system and the PFGE method, but not with the spa typing method. The overall discriminatory power of the DiversiLab system in differentiating diverse MRSA strains proved to be good. We also demonstrated that, in addition to the genetic relatedness analysis of MRSA strains, it is important to obtain accurate epidemiological information in order to perform reliable epidemiological surveillance studies.

The epidemiology and economic impact of varicella-related hospitalizations in Turkey from 2008 to 2010: a nationwide survey during the pre-vaccine era (VARICOMP study)

Varicella can cause complications that are potentially serious and require hospitalization. Our current understanding of the causes and incidence of varicella-related hospitalization in Turkey is limited and sufficiently accurate epidemiological and economical information is lacking. The aim of this study was to estimate the annual incidence of varicella-related hospitalizations, describe the complications, and estimate the annual mortality and cost of varicella in children. VARICOMP is a multi-center study that was performed to provide epidemiological and economic data on hospitalization for varicella in children between 0 and 15years of age from October 2008 to September 2010 in Turkey. According to medical records from 27 health care centers in 14 cities (representing 49.3% of the childhood population in Turkey), 824 children (73% previously healthy) were hospitalized for varicella over the 2-year period. Most cases occurred in the spring and early summer months. Most cases were in children under 5years of age, and 29.5% were in children under 1year of age. The estimated incidence of varicella-related hospitalization was 5.29-6.89 per 100,000 in all children between 0-15years of age in Turkey, 21.7 to 28 per 100,000 children under 1year of age, 9.8-13.8 per 100,000 children under 5years of age, 3.96-6.52 per 100,000 children between 5 and 10years of age and 0.42 to 0.71 per 100,000 children between 10 and 15years of age. Among the 824 children, 212 (25.7%) were hospitalized because of primary varicella infection. The most common complications in children were secondary bacterial infection (23%), neurological (19.1%), and respiratory (17.5%) complications. Secondary bacterial infections (p < 0.001) and neurological complications (p < 0.001) were significantly more common in previously healthy children, whereas hematological complications (p < 0.001) were more commonly observed in children with underlying conditions. The median length of the hospital stay was 6days, and it was longer in children with underlying conditions (<0.001). The median cost of hospitalization per patient was $338 and was significantly higher in children with underlying conditions (p < 0.001). The estimated direct annual cost (not including the loss of parental work time and school absence) of varicella-related hospitalization in children under the age of 15years in Turkey was $856,190 to $1,407,006. According to our estimates, 882 to 1,450 children are hospitalized for varicella each year, reflecting a population-wide occurrence of 466-768 varicella cases per 100,000 children. In conclusion, this study confirms that varicella-related hospitalizations are not uncommon in children, and two thirds of these children are otherwise healthy. The annual cost of hospitalization for varicella reflects only a small part of the overall cost of this disease, as only a very few cases require hospital admission. The incidence of this disease was higher in children <1year of age, and there are no prevention strategies for these children other than population-wide vaccination. Universal vaccination is therefore the only realistic option for the prevention of severe complications and deaths. The surveillance of varicella-associated complications is essential for monitoring of the impact of varicella immunization.

Population-based study of asymptomatic infection with Chlamydia trachomatis among female and male students

There are few epidemiological studies of asymptomatic chlamydial infection among students in non-medical settings with minimal bias and improved accuracy; thus, useful data from screening among students are limited. We aimed to obtain accurate epidemiological information about asymptomatic chlamydial infection among students in non-medical settings. A population-based cross-sectional survey of 10,440 >or=18-year-old asymptomatic students who volunteered for a urine screening test for chlamydia was conducted. The prevalences of asymptomatic infection were 9.5% for women and 6.7% for men. Multivariate analysis revealed the risk factors to be a lifetime history of >or=4 sexual partners for women (odds ratio [OR] 3.17) and inconsistent condom use for men (OR 4.18). For both sexes, younger age at first intercourse was associated with a higher rate of inconsistent condom use. This study produced accurate epidemiological information on asymptomatic chlamydial infection. These results may contribute to the establishment of preventive countermeasures against such infection.

PRE-EMPTING PLANT-PARASITIC NEMATODE LOSSES ON BANANA IN AFRICA: WHICH SPECIES DO WE TARGET?

ISHS III International Symposium on Banana: ISHS-ProMusa Symposium on Recent Advances in Banana Crop Protection for Sustainable Production and Improved Livelihoods PRE-EMPTING PLANT-PARASITIC NEMATODE LOSSES ON BANANA IN AFRICA: WHICH SPECIES DO WE TARGET?

The role of mass media in disease outbreak reporting in the United Republic of Tanzania

Emerging infectious diseases and the growth of information communication technology have produced new demands and possibilities for disease outbreak information and reporting. An analysis of disease outbreak information and reporting by the Tanzanian mass media was carried out to cover a 12-month period between July 2002 and June 2003. Outbreak episodes reported in four local dailies were collected, compiled and analysed. The disease that received the highest coverage was cholera. Cholera outbreaks were frequently reported from the 3 districts in Dar es Salaam Region. Other epidemic-prone diseases received very little coverage. These included meningitis and rabies. With globalisation and high technological information systems, reports of disease outbreaks are more widely disseminated and more easily accessible than ever before. However, the quality of information is no longer controlled and may be provided out of context, often causing unnecessary public anxiety and confusion. It is important that mass media is provided with accurate epidemiological reports if correct information is to reach the public. The role of media in outbreak reporting is herein discussed in relation to the importance of providing timely and accurate epidemiological information. Tanzania Health Research Bulletin Vol.6(2) 2004: 73-77

Biopsy vs. superficial scraping: detection of human papillomavirus 6, 11, 16, and 18 in potentially malignant and malignant oral lesions

Several epidemiologic studies have shown a broad variation in the prevalence of human papillomavirus (HPV) in oral precancerous tissues and oral carcinomas. Biopsies and superficial scrapes of lesions, clinically suspected of HPV infection, were taken from patients with potentially malignant and malignant oral lesions, and subject to HPV DNA detection by PCR-Southern blot analysis. From 22 patients with potentially malignant and malignant lesions analyzed, 41% of the biopsies were HPV DNA positive, whereas 95-100% of the superficial scrapes were positive (McNemar, P < 0.0001). Clinical presumption of HPV infection detected 67% (P < 0.0001) of the HPV DNA positive cases compared with 48% (P < 0.0001) determined by cytology and histopathology. The prevalence of HPV 6, 11, 16 and 18 in the oral mucosa was studied in 59 individuals. While 9% of normal controls were HPV DNA positive, 100% of the patients with potentially malignant and malignant lesions were HPV DNA positive, and the prevailing genotype was HPV 16 followed by HPV 18. The higher HPV DNA detection rate in superficial oral scrapes than in biopsies suggests that accurate epidemiological information on oral HPV infection/oral carcinogenesis depends not only on the DNA detection technique, but also on the tissue/cell sampling procedure.

Syphilis surveillance and trends of the syphilis epidemic in Germany since the mid-90s.

Recent surveillance reports from Europe and the United States show an increase in syphilis cases. Accurate epidemiological information about the distribution of syphilis is important for targeting screening and intervention programmes. The German syphilis notification system changed in 2001 from physician to laboratory-based reporting, which is complemented by a newly introduced sexually transmitted infection (STI) sentinel system. After reaching an all time low during the 1990s, syphilis notifications have increased significantly since 2001, coinciding with the introduction of the new reporting system. However, the increased reported incidence is reflecting a true rise in the number of cases and is not predominantly determined by more underreporting through the previous reporting system. The increase reflects syphilis outbreaks among men who have sex with men (MSM). The first of these outbreaks was observed in Hamburg in 1997. In 2003, incidence in men was ten times higher than in women. An estimated 75% of syphilis cases are currently diagnosed among MSM. A high proportion (according to sentinel data, up to 50%) of MSM diagnosed with syphilis are HIV positive. The continuously high number of syphilis cases diagnosed among heterosexuals in Germany in recent years compared with other western European countries may reflect the higher population movement between Germany and syphilis high incidence regions in south-east and eastern Europe.

Clinical Features, Laboratory Findings and Management of Meningococcal Meningitis in England and Wales: Report of a 1997 Survey

Objectives: To describe the epidemiological, clinical and laboratory features of meningococcal meningitis and the effects of antibiotics on laboratory investigations under current clinical practices in England and Wales.Methods: Using a telephone questionnaire, information was gathered on 103 cases with a clinical diagnosis of meningococcal meningitis. Included were cases with samples submitted to the Public Health Laboratory Service (PHLS), Meningococcal Reference Unit (MRU) over a 5-month period in 1997. Tests included microscopic examination, latex agglutination and culture for Neisseria meningitidis, and at MRU confirmation of identification and characterization of isolates and meningococal polymerase chain reaction (PCR) analysis on blood and cerebrospinal fluids (CSF).Results: Clinically 45% of the cases had predominantly meningitis and 55% had septicaemia and meningitis. Only 29% of the cases received pre-admission benzylpenicillin, and 66% were given antibiotics within an hour of hospital attendance. Microbiological confirmation was achieved in 97 cases, 46 (44%) by traditional tests and 92 (89%) by PCR assay, including some with both. The blood culture positive rate was 23 (22%), but in predominant meningitis the rate was only 10% (5/46). PCR was the sole method of confirmation in 48 cases. Seventy percent of the plasma samples referred were reactive by PCR assay, but all samples taken more than 24 h after hospital antibiotics were non-reactive. PCR-based techniques increased the overall number of cases with a serogroup identified by 44%. Lumbar punctures were performed in 73 of the cases and microbiological confirmation was achieved in 67 (92%) of these cases, compared to 26/30 without lumbar puncture (LP). Eighty-nine percent of the CSF samples referred were reactive by PCR; 50% of the CSF samples taken more than 24 h after hospital antibiotics were reactive, whilst none were positive by culture or microscopy.Conclusion: Due to variable clinical manifestations, early diagnosis and treatment was difficult. Laboratory confirmation has been improved by the introduction of PCR-based techniques. Meningococcal DNA was detected by molecular methods in CSF samples taken up to 72 h after commencement of antibiotics. During this period patients could be stabilized and the chances of complications attendant upon early LP reduced. In addition to providing accurate epidemiological information, confirming the diagnosis may alter the extent and length of follow-up.

The epidemiology of syphilis in the waning years of an epidemic: Houston, Texas, 1991-1997.

National and local syphilis rates have fallen since 1990. Accurate epidemiologic information about the distribution of syphilis during the waning years of an epidemic are important to health care organizations so that they can specifically target screening and intervention programs. To describe the epidemiology of syphilis in Houston, Texas, from 1991 through 1997. Descriptive evaluation of morbidity surveillance data from the Houston Department of Health and Human Services. Between 1991 and 1997, rates for syphilis fell 61%. Rates for primary and secondary syphilis fell 90% among men and women in all race/ethnicity groups; early latent rates fell 81% among blacks, 57% among Hispanics, and 50% among whites. Late latent rates were stable among blacks and whites and increased among Hispanics. The proportion of total cases identified as late latent disease increased from 16% in 1991 to 63% in 1997. Congenital syphilis rates have remained at approximately 2 per 1,000 live births since 1993. Syphilis continues to be a problem in Houston. The medical community and HIV/STD prevention programs need to be vigilant in actively screening high-risk individuals to identify syphilis at earlier stages of the disease and to prevent congenital syphilis.

The importance of epidemiology in understanding eye disease

Most leading causes of visual impairment are age related, so the health care implications of an increasing prevalence of eye disease in the elderly are significant. Epidemiological research provides the foundation to address immediate and long-term needs associated with visual impairment and eye disease. It contributes to a community's knowledge of the presence, diagnosis, characteristics, and distribution of eye conditions affecting the elderly. Obtaining accurate epidemiological information on the extent of visual impairment and eye disease in the community is essential to determine and estimate the cost of primary and secondary eye health care needs.

A simple epidemiological method for animal trypanosomiasis to provide relevant data for effective financial decision-making

The epidemiology of bovine trypanosomiasis on Galana Ranch, Kenya was studied for one year (July 1980–June 1981), using measurements from an experimental population of 3 types of Boran cattle. The results were applied to the estimated ranch population at risk, and an attempt was made to measure the potential economic loss due to trypanosomiasis. The potential losses in beef production due to trypanosomiasis in the ranch population at risk at Galana were estimated at around K.Shs. 8900/km 2, when the stocking rate was 14.2 Tropical Livestock Units per km 2. The estimated potential loss in the total population at risk was approximately K.Shs. 5 million (arround US$ 700 000 at 1981 values). These losses can be minimised by good management techniques based on accurate epidemiological information. Results indicate that Orma-type Boran steers are more resistant to trypanosomiasis than Galana-type Boran steers. Although both types showed similar mortality rates, untreated Orma animals which survived showed a similar growth performance to animals maintained under 3-month Samorin prophylaxis. Untreated Galana Borans lost 14% of their body weight when compared with animals maintained under 3-month Samorin. Also, 305 of the untreated Orma Borans never showed typpanosomes in their blood over the study period, while all corresponding Galana Borans showed parasites; this resulted in a lower measured attact rate in Orma cattle. In 1982, a combination of treating only those animals under trypanosome attack, relating the timing of chemotherapy to measured increased trypanosome attack, and the increased utilisation of the trypano-tolerant Orma Borans resulted in an annual saving of aroung US$ 110 000 in control costs and an increased land usage of approximately 5%.