Caracterización clínica-epidemiológica de COVID-19

Las epidemias y las pandemias son eventos de ocurrencia natural. La aparición de una nueva enfermedad infecciosa supone siempre una situación compleja, sobre todo si lo hace como una epidemia de extensión o gravedad significativa, con el objetivo de describir las características clínico-epidemiológicas en pacientes confirmados con COVID-19. Se realizó un estudio descriptivo y retrospectivo sobre las características clínico-epidemiológicas de los 161 pacientes diagnosticados con esta enfermedad, en el municipio Yara, de la provincia Granma durante el período comprendido de junio de 2020-2021. Se estudiaron las variables: edad, sexo, lugar de infección, presencia o no de síntomas y signos, antecedentes patológicos personales, área de salud y consejo popular. El 60,8% de los afectados fueron del sexo femenino con 98 pacientes y el grupo de 30-44 años de edad quedó representado por 50 pacientes (31.0%); en 150 casos, la transmisión fue mayormente autóctona (93,1%) y asintomática en 86 casos para el 53,4%. De los pacientes sintomáticos fueron las manifestaciones respiratorias, los principales síntomas con 70 casos para el 93,3%, 63 pacientes tenían antecedentes personales de hipertensión arterial (39,1%). El área de salud que más casos notificó fue "Luis Enrique de la Paz" con 106 pacientes para el 65,8% y Yara el consejo popular más afectado con 72 casos (44,7%), la mayoría de los pacientes fueron del sexo femenino, predominó la transmisión autóctona y la presentación asintomática. La epidemia en el municipio Yara se comportó similar al resto del país.

Epidemics and pandemics are naturally occurring events. The emergence of a new infectious disease is always a complex situation, especially when it occurs as an epidemic of significant spread or severity. The aim of this study was to describe the clinical-epidemiologic characteristics of patients confirmed with COVID-19. A descriptive and retrospective study was carried out on the clinical-epidemiological characteristics of 161 patients diagnosed with this disease, in the municipality of Yara, province of Granma. The following variables were studied: age, sex, site of infection, presence or not of symptoms and signs, personal pathological antecedents, health area and locality. Out of the total, 98 patients were female (60.8%), and the age group 30-44 years was represented by 50 patients (31.0%). Transmission was generally autochthonous in 150 cases (93.1%), and asymptomatic in 86 cases (53.4%). Among the symptomatic patients, respiratory manifestations were the main symptom in 70 cases (93.3%). Also, 63 patients had a personal medical history of hypertension (39.1%). Luis Enrique de la Paz was the health area that reported the most cases with 106 patients (65.8%), and Yara was the most affected locality with 72 cases (44.7%). The majority of patients were female; and autochthonous transmission and asymptomatic presentation predominated. The epidemic in Yara municipality behaved alike in the whole country.

Epidemias e pandemias são eventos naturais. O surgimento de uma nova doença infecciosa é sempre uma situação complexa, especialmente se for uma epidemia de extensão ou gravidade significativa, com o objetivo de descrever as características clínico-epidemiológicas em pacientes confirmados com COVID-19. Foi realizado um estudo descritivo e retrospectivo sobre as características clínico-epidemiológicas dos 161 pacientes diagnosticados com essa doença, no município de Yara, província de Granma, no período de junho de 2020 a 2021, as variáveis foram estudadas: idade, sexo, local de infecção, presença ou não de sintomas e sinais, história patológica pessoal, área de saúde e conselho popular. O 60,8% dos acometidos eram do sexo feminino com 98 pacientes e a faixa etária de 30 a 44 anos foi representada por 50 pacientes (31,0%); Em 150 casos, a transmissão foi predominantemente autóctone (93,1%) e assintomática em 86 casos para 53,4%, entre os sintomáticos foram manifestações respiratórias, sendo os principais sintomas 70 casos para 93,3%, 63 pacientes tinham história pessoal de hipertensão arterial (39,1%). A área de saúde que mais registrou casos foi "Luis Enrique de la Paz" com 106 pacientes para 65,8% e Yara o município popular mais afetado com 72 casos (44,7%), a maioria dos pacientes era do sexo feminino, de transmissão autóctone e apresentação assintomática. A epidemia no município de Yara se comportou de forma semelhante ao resto do país.

Study on efficacy and regulation of inflammatory factors with oseltamivir phosphate by different time series of interventions in a murine model of influenza A H1N1 virus infection / 中国药理学通报

Aim To compare the effects of different time sequence interventions on virus infected mice by using oseltamivir (Tamiflu) as a "tool drug" in view of the current situation of the too early the administration time of antiviral in vivo experiment, so as to provide a basis for selecting a reasonable model intervention time point for antiviral drug research. Methods Balb/c mice were randomly divided into six groups. The virus infection model was established by intranasal infection with influenza virus (0.25 TCID50). Tamiflu-1 group and Tamiflu-2 group were administered orally on 1st and 4th day after exposure. The body mass, survival rate, organ index, viral load and inflammatory factor content were measured. Results Compared with the blank control group, the body weight of the mice in the model group decreased and the lung index increased significantly (P < 0.05). The expression levels of 13 inflammatory factors in model 2 group were significantly different ( P < 0.05). Compared with the model-1 group ,the lung index and spleen index of the Tamiflu-1 group decreased significantly (P < 0.05). Compared with the mode-2 group,the lung index in the Tamiflu-2 group was significantly lower (P <0.05) ,and the thy-mus index was significantly higher (P<0.05). The viral load was 0. 03 times that of the model-2 group. The expression levels of 13 inflammatory factors were significantly different (P < 0. 05). Conclusions The symptoms of the mice in Scheme 2 are more obvious and stable after exposure. After administration, the lung inflammation damage is alleviated. Considering the latency, drug intervention is in line with the drug indications when the model animals show symptoms. It will be more reasonable and accurate whether in the model evaluation or drug evaluation.

Analysis of disease progression and influencing factors of HIV-infected persons in 2010-2020 / 公共卫生与预防医学

Objective To investigate the disease progression and influencing factors of human immunodeficiency virus (HIV)-infected persons in Sanya area from 2010-2020. Methods Data of HIV infected cases reported in XX region from January 2014 to January 2020 were collected through the National AIDS Comprehensive Prevention and Control Information System. The incidence of AIDS was calculated by the life expectancy method, and the single factors influencing the progression of HIV infection were analyzed from the aspects of sex, age, BMI, nationality, marital status, educational level, highly active anti-retroviral therapy (HAART), anemia, route of transmission, CD4+ cell count, and co-infection of other viruses. Results A total of 761 HIV-infected cases were reported in Sanya areaFrom January 2010 to January 2020, of which 103 had progressed to AIDS (13.53%), the incidence of AIDS was 6.01/100 person-years, the average incubation period was 4.63 years; There were 31 death cases, and the all-cause mortality rate was 1.81/100 person years; Gender, age, HAART treatment status, anemia, CD4+ cell count, and other viral infections were single factors that affect the disease progression of HIV-infected persons (χ2=16.803, 13.362, 15.954, 20.119, 16.039, 15.711, P+ cell count, and other viral infections were independent risk factors that affect the disease progression of HIV-infected persons (P=0.014, 0.007, 0.017, 0.009, 0.001, 0.001). Conclusion The incubation period is an important stage of the disease progression of HIV-infected patients, moreover, age, HAART treatment status, anemia, CD4+ cell count, and other viral infections are all independent risk factors that affect the disease progression of HIV-infected patients.

Examining geographical disparities in the incubation period of the COVID-19 infected cases in Shenzhen and Hefei, China

BACKGROUND@#Current studies on the COVID-19 depicted a general incubation period distribution and did not examine whether the incubation period distribution varies across patients living in different geographical locations with varying environmental attributes. Profiling the incubation distributions geographically help to determine the appropriate quarantine duration for different regions.@*METHODS@#This retrospective study mainly applied big data analytics and methodology, using the publicly accessible clinical report for patients (n = 543) confirmed as infected in Shenzhen and Hefei, China. Based on 217 patients on whom the incubation period could be identified by the epidemiological method. Statistical and econometric methods were employed to investigate how the incubation distributions varied between infected cases reported in Shenzhen and Hefei.@*RESULTS@#The median incubation period of the COVID-19 for all the 217 infected patients was 8 days (95% CI 7 to 9), while median values were 9 days in Shenzhen and 4 days in Hefei. The incubation period probably has an inverse U-shaped association with the meteorological temperature. The warmer condition in the winter of Shenzhen, average environmental temperature between 10 °C to 15 °C, may decrease viral virulence and result in more extended incubation periods.@*CONCLUSION@#Case studies of the COVID-19 outbreak in Shenzhen and Hefei indicated that the incubation period of COVID-19 had exhibited evident geographical disparities, although the pathological causality between meteorological conditions and incubation period deserves further investigation. Methodologies based on big data released by local public health authorities are applicable for identifying incubation period and relevant epidemiological research.

Analysis of clinical characteristics and blood purification effect of mushroom poisoning in children in Hunan Province / 中国小儿急救医学

Objective:To analyze the epidemiological characteristics, clinical characteristics and blood purification effect of mushroom poisoning in children.Methods:A retrospective study was conducted on 51 children with acute mushroom poisoning admitted to Hunan Children′s Hospital from 2002 to 2020.The epidemiological and clinical characteristics were analyzed, and the prognosis of children with different incubation periods was analyzed and compared.Among them, 36 critically ill children were treated with blood purification.Results:The age distribution was 66(43, 115)months.Mushroom poisoning had obvious seasonal and spatial aggregation.The first symptom was mainly manifested by digestive tract, which was manifested as vomiting, abdominal pain and diarrhea, accounting for 94.1% patients(48/51). The gastrointestinal tract type accounted for 45.1%(23/51) of the clinical types and the multi-organ damage type accounted for 51.0% patients(26/51). The length of hospital stay was 6(3, 11)days.Among them, early onset accounted for 45.1% patients(23/51), late onset accounted for 54.9% patients(28/51). Early onset hospitalization was shorter, about 4(2, 7)days, and fewer organs 1(0, 3) were damaged.The length of hospital stay of late onset was 8(3, 12)days, and the number of damaged organs was 4(2, 4). There was a statistically significant difference( P<0.05). Late onset patients had more severe organ function damage, including liver function, coagulation function, renal function, myocardial enzyme, and there was no significant difference in the final outcome between two groups.In 36 children who were given blood purification treatment, alanine aminotransferase, aspartate aminotransferase, prothrombin time, international normalized ratio, blood urea nitrogen, and lactate dehydrogenase were significantly improved, with statistically significant differences( P<0.05). Conclusion:Mushroom poisoning has obvious seasonal and geographical distribution characteristics; the first manifestation is mainly gastrointestinal symptoms; the clinical types are more common in gastrointestinal and multiple organ damage types.Children with early onset have shorter hospital stays and fewer complications than later onset.Blood purification treatment can significantly improve liver function, kidney function and blood coagulation function in children with toadstool poisoning.

Corona virus pandemic: current scenario and future hopes

Whenever we human beings challenge the existence of the god or tried to prove ourselves superior to the nature. The Nature bounces back in the form of these pandemics of infectious disease which forced us to either surrender or to lockdown ourselves in homes. The current outbreak of Corona Virus Disease-19 (COVID-19) is the same warning from nature. It is spreading very fast from one country to other and almost affects the whole world. We have many unanswered questions. Currently in absence of any definitive treatment, prevention is an only option. But future hopes are still there. This article gives a brief and accurate detail of COVID-19 pandemic regarding current situation and future hopes.

The Importance of Social Distancing

@#As countries battle the COVID-19 pandemic, it is important to understand why certain public health policies and practices are adopted. This article seeks to explain basic communicable disease epidemiological concepts such as Reproductive Ratio, Serial Interval and Incubation Period. The article also demonstrates the effects of exponential growth on cluster size. These concepts help us to better understand the "disease dynamics" of COVID-19 and so enable us to understand better the policies and practices employed to combat COVID-19, e.g. social distancing, personal hygiene and mask-wearing.

Study on assessing early epidemiological parameters of coronavirus disease epidemic in China / 中华流行病学杂志

Objective@#To study the early dynamics of the epidemic of coronavirus disease (COVID-19) in China from 15 to 31 January, 2020, and estimate the corresponding epidemiological parameters (incubation period, generation interval and basic reproduction number) of the epidemic.@*Methods@#By means of Weibull, Gamma and Lognormal distributions methods, we estimated the probability distribution of the incubation period and generation interval data obtained from the reported COVID-19 cases. Moreover, the AIC criterion was used to determine the optimal distribution. Considering the epidemic is ongoing, the exponential growth model was used to fit the incidence data of COVID-19 from 10 to 31 January, 2020, and exponential growth method, maximum likelihood method and SEIR model were used to estimate the basic reproduction number.@*Results@#Early COVID-19 cases kept an increase in exponential growth manner before 26 January, 2020, then the increase trend became slower. The average incubation period was 5.01 (95%CI: 4.31-5.69) days; the average generation interval was 6.03 (95%CI: 5.20-6.91) days. The basic reproduction number was estimated to be 3.74 (95%CI: 3.63-3.87), 3.16 (95%CI: 2.90-3.43), and 3.91 (95%CI: 3.71-4.11) by three methods, respectively.@*Conclusions@#The Gamma distribution fits both the generation interval and incubation period best, and the mean value of generation interval is 1.02 day longer than that of incubation period. The relatively high basic reproduction number indicates that the epidemic is still serious; Based on our analysis, the turning point of the epidemic would be seen on 26 January, the growth rate would be lower afterwards.

The preliminary analysis on the characteristics of the cluster for the Corona Virus Disease / 中华流行病学杂志

Since December 2019, Corona Virus Disease (COVID-19), a new emerging infection disease occurred in Wuhan, has spread in 27 countries and regions. The clusters of many cases were reported with the epidemic progresses. We collected currently available information for 377 COVID-19 clusters (1 719 cases), excluded the hospital clusters and Hubei cases, during the period from January 1, 2020 to February 20, 2020. There were 297 family clusters (79%), case median 4; 39 clusters of dining (10%), case median 5; 23 clusters of shopping malls or supermarkets (6%), case median 13; 12 clusters of work units (3%), case median 6, and 6 clusters of transportation. We selected 325 cases to estimate the incubation period and found its range is 1 to 20 days, median was 7 days, and mode was 4 days. The analysis of the epidemic situation in a department store in China indicates that there is a possibility of patients as the source of infection during the incubation period of the epidemic. From February 5, 2020 to February 21, 2020, 634 persons were infected in the Diamond Princess Liner. All persons are susceptible to SARS-CoV-2. The older, patients during the incubation period and the worse environment may be the cause of the cases rising. The progress of the two typical outbreaks clearly demonstrates the spread of the early cases in Wuhan. Whatever happens, screening and isolating close contacts remains essential except for clinical treatment during the epidemic. Especially for the healthy people in the epidemic area, isolation is the key.

Diagnosis of new occupational lung tumor in Guangdong Province / 中国职业医学

OBJECTIVE: To summarize and analyze the diagnostic ideas of new occupational lung tumors in Guangdong Province.METHODS: According to the Law of the People′s Republic of China on the Prevention and Control of Occupational Disease and the GBZ 94-2002 Diagnostic Criteria of Occupational Cancer, the key diagnostic points of 6 new occupational lung tumors diagnosed in Guangdong Province from 2010 to 2011 were analyzed. RESULTS: There were 9 cases of 6 new kinds of new occupational tumors were diagnosed in Guangdong Province in 2010-2011. The cases included 3 occupational lung cancer of coke oven workers, 2 occupational lung cancer caused by asbestos, 1 occupational mesothelioma caused by asbestos, 1 occupational lung cancer caused by arsenate, 1 occupational lung cancer caused by chromate salt, and 1 occupational lung cancer caused by asphalt. During the process, the diagnosis was based on the principles of the comprehensive analysis and the attribution diagnosis, combined with occupational history, occupational disease hazard exposure history, clinical data and auxiliary examination results. If the patients were diagnosed with a primary tumor, the patients′ exposure history to occupational carcinogens should be tracked, traced and confirmed, and the diagnosis should be confirmed by referring to the list of occupational carcinogens and literature reports of the International Labor Organization, and not limited to only the personnel in a particular industry. CONCLUSION: During the diagnostic process of occupational tumors, attention should be paid to confirm the exposure history of occupational carcinogen. The key is to determine the exposure of corresponding occupational carcinogen, the route and the time of exposure and the incubation period.

Duration of Pulmonary Tuberculosis Infectiousness under Adequate Therapy, as Assessed Using Induced Sputum Samples / 결핵및호흡기질환

BACKGROUND: A sputum culture is the most reliable indicator of the infectiousness of pulmonary tuberculosis (PTB); however, a spontaneous sputum specimen may not be suitable. The aim of this study was to evaluate the infectious period in patients with non–drug-resistant (DR) PTB receiving adequate standard chemotherapy, using induced sputum (IS) specimens. METHODS: We evaluated the duration of infectiousness of PTB using a retrospective cohort design. RESULTS: Among the 35 patients with PTB, 22 were smear-positive. The rates of IS culture positivity from baseline to the sixth week of anti-tuberculosis medication in the smear-positive PTB group were 100%, 100%, 91%, 73%, 36%, and 18%, respectively. For smear-positive PTB cases, the median time of conversion to culture negativity was 35.0 days (range, 28.0–42.0 days). In the smear-negative PTB group (n=13), the weekly rates of positive IS culture were 100%, 77%, 39%, 8%, 0%, and 0%, respectively, and the median time to conversion to culture-negative was 21.0 days (range, 17.5–28.0 days). CONCLUSION: The infectiousness of PTB, under adequate therapy, may persist longer than previously reported, even in patients with non-DR PTB.

Gray mold in immature fig fruit: pathogenicity and growth temperature / Mofo cinzento em frutos imaturos de figo: patogenicidade e temperatura para crescimento

ABSTRACT: Several diseases can be associated with figs but recently a fruit rot was observed in green fruit. The purpose of this study was to determine the pathogenicity of Botrytis sp., to quantify incubation period (IP) and latent period (LP), to verify the optimum temperature for mycelial growth, and to identify the different species of Botrytis sp. isolated from immature figs. Botrytis sp. isolated from figs proved to be pathogenic to immature fruit with and without wounding the fruit surface and ostiole. The IP period was 3 days on fruit with wounds and 5 days on fruit inoculated within the ostiole (without wound). The LP was 6 days in all treatments. The optimum temperature for mycelial growth was 18°C. Inferred from sequences of a segment comprising the ITS region of ribosomal DNA concluded that the isolates are Botrytis cinerea.

RESUMO: Várias doenças podem estar associadas com figos, mas recentemente uma podridão dos frutos foi observada em frutos verdes. O objetivo deste estudo foi determinar a patogenicidade de Botrytis sp., quantificar o período de incubação (PI) e o período de latência (PL), verificar a temperatura ótima para o crescimento micelial e identificar as diferentes espécies de Botrytis sp. isoladas a partir de frutos imaturos de figo. Botrytis sp. isolado a partir de figos provou ser patogênico em frutos imaturos com e sem ferimento na superfície dos frutos e no ostíolo. O PI foi de 3 dias em frutos com ferimento e 5 dias em frutos inoculados no ostíolo e sem ferimento. O PL foi de 6 dias em todos os tratamentos. A temperatura ótima de crescimento micelial foi18°C. A partir de sequências de um segmento que compreende a região de ITS do DNA ribossomal, concluiu-se que os isolados são Botrytis cinerea.

Estimation of the size of the iatrogenic Creutzfeldt-Jakob disease outbreak associated with cadaveric dura mater grafts in Korea / 한국역학회지

OBJECTIVES: This study estimated the overall incidence of iatrogenic Creutzfeldt-Jakob disease (iCJD) based on dura graft cases in Korea using a mathematical model. METHODS: We estimated the number of annual dura grafts performed between 1980 and 1995 by applying the proportion of dura grafts recorded by the Health Insurance Review Agency claim dataset in Korea to the number of nationwide neurosurgery cases. The distribution of the incubation period was assumed to fall under a Weibull distribution with density function or a log-logistic distribution with density function. RESULTS: The total number of neurosurgery procedures performed from 1980 to 1995 was estimated to be 263,945, and among those operations, 37% used dura graft products. Between the years of 1980 and 2020, our model predicted that the total number of iCJD cases would be between 14.9 and 33.2 (95% confidence interval [CI], 13.4 to 50.9). Notably, we estimated that the cumulative number of iCJD cases caused by dura grafts between 1980 and 2011 was approximately 13.3 to 27.3 (95% CI, 12.2 to 40.6). CONCLUSIONS: Based on our model, we postulate that the incidence of iCJD will sharply decline from 2012 to 2020. However, additional new cases are still expected, which necessitates a strong national surveillance system.

Epidemiologic Parameters of the Middle East Respiratory Syndrome Outbreak in Korea, 2015 / 감염과화학요법

BACKGROUND: Epidemiologic parameters are important in planning infection control policies during the outbreak of emerging infections. Korea experienced an outbreak of Middle East Respiratory Syndrome coronavirus (MERS-CoV) infection in 2015, which was characterized by superspreading events in healthcare settings. We aimed to estimate the epidemiologic parameters over time during the outbreak to assess the effectiveness of countermeasures. MATERIALS AND METHODS: Publicly available data pertaining to the MERS outbreak in Korea were collected. We estimated the incubation periods of 162 cases whose sources of exposure were identified and the temporal trend was evaluated. Factors influencing incubation duration were analyzed. The generational reproduction number (R(g)) and case reproduction number (R(c)) were estimated over time. RESULTS: The estimated median incubation period was 7.4 days (95% CI, 6.9-8.0). Median incubation periods tended to be longer over time as the disease generation progressed: 6.16 days (95% CI, 5.38-6.97), 7.68 days (95% CI, 7.04-8.44), and 7.95 days (95% CI, 6.25-9.88) in the first, second, and third generations, respectively. The number of days of illness in the source cases at the time of exposure inversely correlated with the incubation periods in the receiving cases (HR 0.91 [95% CI, 0.84-0.99] per one illness day increase; P=0.026). This relationship was consistent (HR 0.83 [95% CI, 0.74-0.93] per one illness day increase) in the multivariable analysis incorporating clinical characteristics, the order of generation, and a link to superspreaders. Because the third generation cases were exposed to their source cases in the early stage (median one day) compared to the second generation cases (median 6 days), the temporal trend of incubation periods appears to be influenced by early isolation of symptomatic cases and reduction of potential exposure to source cases in the later stage. R(g) declined rapidly from 28 to 0.23 in two generations. R(c) dropped below the epidemic threshold at one on May 31, 2015, which approximately coincided with the initiation of the stringent countermeasures. CONCLUSIONS: Despite the initial delay, the stringent countermeasures targeted towards second generation cases appeared to effectively contain the MERS outbreak in Korea as suggested by the decline of R(c) shortly after implementation. Except for superspreading events, the transmission potential for MERS-CoV seems to be low. Further research should be focused on characterizing superspreaders in comparison to non-transmitting cases with regard to environmental, behavioral, and virologic and host genetic factors in order to better prepare for future outbreaks of MERS-CoV.

Research on pattern reversal visual evoked potential of children with spastic cerebral palsy / 国际眼科杂志(Guoji Yanke Zazhi)

AlM: To explore the judgment of pattern reversal visual evoked potential on visual function and injured part of children with spastic cerebral palsy.METHODS: There were two groups in this study. 30 children with spastic cerebral palsy ( quadriplegia: 15, diplegia:15) were selected as observation group, while 30 normal children were selected as control group with randomized controlled trial. The changes of half-view and full- view incubation period and amplitude were observed by pattern reversal visual evoked potential.RESULTS: Full-view pattern reversal visual evoked potential: the P100 incubation period of the observation group was 113. 55 ± 8. 14ms, and the P100 amplitude was 23. 08±15. 41μV. The P100 incubation period of the control group was 105. 05 ± 5. 58ms, and the P100 amplitude was 31. 65±7. 37μV. From the comparison on P100 incubation and P100 amplitude between two groups, the difference was statistically significant ( P0. 05). Compared to the control group, each eye and each view latency of observation group were higher, the difference was statistically significant ( P<0. 05). The change of the incubation period of the full-view and half - view pattern reversal visual evoked potential took place in the lesion of the visual pathway:including optic neuropathy, some optic nerve lesion, lesion after optic chiasma, and optic chiasma lesion. Among them, the lesion after the optic chiasma was the most common.CONCLUSlON:Pattern reversal visual evoked potential can help people to understand the visual impairment and injury of children with spastic cerebral palsy in order to identify the abnormal children and early intervention.

Statistical estimations forPlasmodium vivaxmalaria in South Korea

Objective:To calculate the numbers of weekly infections and prevalence of malaria, and to predict future trend of malaria incidences in South Korea.Methods:Weekly incidences of malaria for 13 years from the period 2001-2013 in South Korea were analyzed. The back-calculation equations were used with incubation period distributions. The maximum likelihood estimation for Poisson model was also used. The confidence intervals of the estimates were obtained by a bootstrap method. A regression model for time series of malaria incidences over 13 years was fitted by the non-linear least squares method, and used to predict futuretrend. Results:The estimated infection curve is narrower and more concentrated in the summer than in the incidence distribution. Infection started around the 19th week and was over around the 41st week. The maximum weekly infection 110 was obtained at the 29th week. The prevalence at the first week was around 496 persons, the minimum number was 366 at 22nd week, and the maximum prevalence was 648 at 34th week. Prevalence drops in late spring with people that falling ill and had had long incubation periods and rose in the summer with new infections. Our future forecast based on the regression model was that an increase at year 2014 compared to 2013 may reach a peak (at maximum about 70 weekly cases) at year 2015, with a decreasing trend after then.Conclusions:This work shows that back-calculation methods could work well in estimating the infection rates and the prevalence of malaria. The obtained results can be useful in establishing an efficient preventive program for malaria infection. The method presented here can be used in other countries where incidence data and incubation period are available.

Statistical estimations for Plasmodium vivax malaria in South Korea

OBJECTIVE@#To calculate the numbers of weekly infections and prevalence of malaria, and to predict future trend of malaria incidences in South Korea.@*METHODS@#Weekly incidences of malaria for 13 years from the period 2001-2013 in South Korea were analyzed. The back-calculation equations were used with incubation period distributions. The maximum likelihood estimation for Poisson model was also used. The confidence intervals of the estimates were obtained by a bootstrap method. A regression model for time series of malaria incidences over 13 years was fitted by the non-linear least squares method, and used to predict futuretrend.@*RESULTS@#The estimated infection curve is narrower and more concentrated in the summer than in the incidence distribution. Infection started around the 19th week and was over around the 41st week. The maximum weekly infection 110 was obtained at the 29th week. The prevalence at the first week was around 496 persons, the minimum number was 366 at 22nd week, and the maximum prevalence was 648 at 34th week. Prevalence drops in late spring with people that falling ill and had had long incubation periods and rose in the summer with new infections. Our future forecast based on the regression model was that an increase at year 2014 compared to 2013 may reach a peak (at maximum about 70 weekly cases) at year 2015, with a decreasing trend after then.@*CONCLUSIONS@#This work shows that back-calculation methods could work well in estimating the infection rates and the prevalence of malaria. The obtained results can be useful in establishing an efficient preventive program for malaria infection. The method presented here can be used in other countries where incidence data and incubation period are available.

Statistical estimations for Plasmodium vivax malaria in South Korea

Objective: To calculate the numbers of weekly infections and prevalence of malaria, and to predict future trend of malaria incidences in South Korea. Methods: Weekly incidences of malaria for 13 years from the period 2001-2013 in South Korea were analyzed. The back-calculation equations were used with incubation period distributions. The maximum likelihood estimation for Poisson model was also used. The confidence intervals of the estimates were obtained by a bootstrap method. A regression model for time series of malaria incidences over 13 years was fitted by the non-linear least squares method, and used to predict futuretrend. Results: The estimated infection curve is narrower and more concentrated in the summer than in the incidence distribution. Infection started around the 19th week and was over around the 41st week. The maximum weekly infection 110 was obtained at the 29th week. The prevalence at the first week was around 496 persons, the minimum number was 366 at 22nd week, and the maximum prevalence was 648 at 34th week. Prevalence drops in late spring with people that falling ill and had had long incubation periods and rose in the summer with new infections. Our future forecast based on the regression model was that an increase at year 2014 compared to 2013 may reach a peak (at maximum about 70 weekly cases) at year 2015, with a decreasing trend after then. Conclusions: This work shows that back-calculation methods could work well in estimating the infection rates and the prevalence of malaria. The obtained results can be useful in establishing an efficient preventive program for malaria infection. The method presented here can be used in other countries where incidence data and incubation period are available.

The Long and Short Incubation Periods of Plasmodium vivax Malaria in Korea: The Characteristics and Relating Factors / 감염과화학요법

BACKGROUND: The cases of Plasmodium vivax malaria in Korea are mixed with long and short incubation periods. This study aims to define clinico-epidemiologic chracteristcs of Plasmodium vivax malaria in Korea. MATERIALS AND METHODS: We selected the civilian cases infected with P. vivax malaria in Korea from the epidemiological investigation data of 2001 to 2010, whose incubation periods could be estimated. The long and short incubation periods were defined by duration of infection and onset time, and the cases were compared by demographic factors and clinical symptom, infection and onset time. The correlation was analyzed between the proportion of cases in the infected region with the long incubation period and meteorological factors along with latitude. RESULTS: The length of the mean short and long incubation periods for the cases were 25.5 days and 329.4 days, respectively. The total number of the study subjects was 897, and the number cases of short and long incubation periods was 575 (64.1%) and 322 (35.9%), respectively. The aspect of incubation period showed a significant difference by region of infection; there was a higher proportion of long incubation period infection cases in Gangwon-do than in Gyeonggi-do and Incheon. The proportion of long incubation period cases showed significant correlation with latitude and temperature of August and September of the infected regions. CONCLUSIONS: Incubation period of P. vivax malaria in Korea showed significant difference by infected region, infection and onset time and the proportion of long incubation period cases showed significant correlation with latitude and meteorological factors of the infected regions.

Malária vivax com tempo de incubação prolongado, detectada no Distrito Federal: relato de três casos / Vivax malaria with long incubation period, detected in the Federal District: three case reports

Foram detectados três casos de malária vivax em Brasília, Distrito Federal, área considerada indene, procedentes da Amazônia, seis meses após estarem residindo em Brasília. Período de incubação prolongado tem sido descrito apenas para infecções por cepas de Plasmodium vivax de clima temperado. Não foi possível genotipar os parasitos.

Three cases of vivax malaria originating from the Amazon region were detected after living in Brasilia, Federal District (considered to be a non-endemic area), for six months. Long incubation periods have been described only for infections due to strains of Plasmodium vivax in temperate climates. It was not possible to genotype the parasites.