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.

Estimating risk factors of urban malaria in Blantyre, Malawi: A spatial regression analysis

Objective: To estimate risk factors of urban malaria in Blantyre, Malawi, with the goal of understanding the epidemiology and ecology of the disease, and informing malaria elimination policies for African urban cities that have markedly low prevalence of malaria. Methods: We used a case-control study design, with cases being children under the age of five years diagnosed with malaria, and matched controls obtained at hospital and communities. The data were obtained from Ndirande health facility catchment area. We then fitted a multivariate spatial logistic model of malaria risk. Covariate and risk factors in the model included child-specific, household and environmental risk factor (nearness to garden, standing water, river and swamps). The spatial component was assumed to follow a Gaussian process and model fitted using Bayesian inference. Results: Our findings showed that children who visited rural areas were 6 times more likely to have malaria than those who did not [odds ratio (OR) = 6.66, 95% confidence interval (CI): 4.79-9.61]. The risk of malaria increased with age of the child (OR = 1.01, 95% CI: 1.003-1.020), but reduced with high socio-economic status compared to lower status (OR = 0.39, 95% CI: 0.25-0.54 for the highest level and OR = 0.67, 95% CI: 0.47-0.94 for the medium level). Although nearness to a garden, river and standing water showed increased risk, these effects were not significant. Furthermore, significant spatial clusters of risk emerged, which does suggest other factors do explain malaria risk variability apart from those established above. Conclusions: As malaria in urban areas is highly fuelled by rural-urban migration, emphasis should be to optimize information, education and communication prevention strategies, particularly targeting children from lower socio-economic position.

A Case of Cutaneous Larva Migrans on the Neck without a History of Travel to an Endemic Area / 대한피부과학회지

Cutaneous larva migrans is a characteristic serpiginous creeping eruption that is caused by the migration of the larval form of neomatodes in the skin. It is caused by hookworm larvae, which are present in the feces of infected dogs and cats. The skin lesions progressively evolve at a rate of 2~3 cm daily. Most cases have a travel history to tropical and subtropical countries, but our patient had no travel history to an endemic area and no contact history with the feces of dogs and cats. We report herein on a case of cutaneous larva migrans on the neck and the patient did not have a travel history to an endemic area and the lesions showed relatively rapid progression.

Clinical Characteristics of Amebic Colitis as Diagnosed by using Colonoscopic Findings

PURPOSE: Nowadays, with improvements in hygiene and in the sewage system, the prevalence of amebic colitis in Korea is declining. However, amebic colitis still occurs every year. We investigated the clinical features of current patients with amebic colitis and compared the results with those for a past endemic period in Korea. METHODS: From June 2000 to June 2005, 10 patients were diagnosed in the Digestive endoscopy center of Song Do colorectal hospital as having amebic colitis. We evaluated their medical histories, clinical characteristics, and colonoscopic findings. RESULTS: The male-to-female ratio was 1.5 : 1. The mean age was 38.4+/-11.4 years. The mean diagnostic period from occurrence of symptoms to diagnosis was 20.4+/-17.5 days. The clinical symptoms of amebic colitis were diarrhea (80%), bloody stool (70%), mucoid stool (60%), abdominal pain (50%), fever, weight loss, nausea, and fatigue. Seven patients (70%) had a history of travel, and six of those seven patients had taken trips abroad. The foreign areas of travel included India (50%), Indonesia (28.6%), and Japan (16.7%). The diagnostic methods were colonoscopic biopsies to detect trophozoites of Entameba histolytica (90%) and serologic tests for the anti-ameba antibody (10%). The most common colonic locations of the lesions were the cecum (80%) and the rectum (80%). Another was the ascending colon (30%); pan-colonic involvement was also seen (10%). CONCLUSIONS: In the past, the cause of amebic colitis in Korea was poor hygiene. Nowadays, however, travel to amebiasis-endemic areas may be the most important cause. Therefore, the travel history of diarrheal patients is an important diagnostic factor in cases of amebic colitis and a differential diagnosis factor in cases of inflammatory bowel disease.