A mathematical model of Plasmodium falciparum transmission incorporating drug resistance: Simulations of the Solomon Islands situation

The Solomon Islands are known as a high endemic region of malaria. The resistance of Plasmodium falciparum to chloroquine has been confirmed since 1980 in the Solomon Islands, and the spread of chloroquine resistance is a big hurdle to malaria control. We have constructured the model for P. falciparum making allowance of chloroquine resistance. We distinguish the infection of resistance strains from that of sensitive strains in both the human and the vector populations. Since the overall parasite rate and the parasite rate of gametocytes for P.　falciparum are strongly dependent on age, the human population is divided into 7 age groups in the model. The epidemiological parameters are determined by malariological survey in northeastern Guadalcanal (Ishii et al.) and the sporozoite rate in vector population is assumed as 0.1% based on the entomological study (Harada et al.) Our study aims at estimating the effect of mass drug administration under the presence of drug-resistance and also analyzing the escalation of drug-resistance through the transmission model for P. falciparum which can deal with chloroquine resistance

Analysis of the effectiveness of control strategies against bioterrorist smallpox attacks by using Individual Based Model

We carried out simulations of various scenarios for bioterrorist attacks using smallpox occurring in a virtual area set up on the basis of the census of Okayama-city, Japan, which predict the effect of control strategies against bioterrorism and the loss scale. On simulating a smallpox epidemic, we followed the method of the Individual Based Model stochastically, which can treat the population in the virtual area as individuals. Individuals have personal information, behavior patterns, and interactions among social groups. We took into consideration the influence of residual immunity due to past vaccination. We considered Traced Vaccination (TV) and Mass Vaccination (MV) strategies against bioterrorism. We investigated the effect of TV and MV strategies on the suppression of smallpox epidemics. Consequently, the TV strategy was found to have higher effectiveness than the MV strategy

The evaluation of control measures against Schistosoma mekongi in Cambodia by a mathematical model

We constructed a mathematical model for the transmission of Schistosoma mekongi in Cambodia. The simulation of the model will be instrumental in planning schistosomiasis control measures. The model includes two definitive hosts, humans and dogs, as animal reservoirs. Dogs are recognized to play an important role in schistosomiasis transmission in Cambodia. For the purpose of dealing with age-specific prevalence and intensity of infection, the human population was classified into eight age categories in the model. To describe the seasonal fluctuation of the intermediate host population of S. mekongi, the "Post-Spate Survival" hypothesis was adopted for the population dynamics of Neotricula aperta present in the Mekong River. We carried out simulations to evaluate the effect of universal treatment (UT) and targeted mass treatment (TT) with praziquantel on the reduction in prevalence of S. mekongi. The simulations indicated that biyearly UT for 8 years or yearly TT for 5 years after three courses of yearly UT could reduce the prevalence to below 5% when a UT or TT coverage of 85% of inhabitants was achieved. The simulation suggested that the suppression of S. mekongi in Cambodia would be possible by UT or TT with a high coverage rate.</p

Analysis of the effectiveness of control measures against Schistosoma mekongi using an intra- and inter-village model in Champasak Province, Lao PDR

Schistosomiasis mekongi is prevalent in the Khong district of Lao PDR, made up of one big island. Khong, and numerous small islands in the Mekong River. Schistosoma mekongi is spread by Neotricula aperta as the intermediate host along the Mekong River. Therefore, even if an epidemic of S. mekongi were stamped out in a certain village, infection may recur if the source of infection is a village located in the upper reaches of the Mekong River. The purpose of this study was to construct a mathematical model for the transmission of S. mekongi among villages from the upper to lower Mekong River to estimate the effect of control measures against it. The chief characteristic of the present model is competence in dealing with the spread of infection among villages through the Mekong River in consideration of the reduction in longevity of cercariae and miracidia and their diffusion in the river. The model also takes into account seasonal fluctuation in the water level of the Mekong River, which affects human behavior in terms of water contact. The results of simulations indicated that the prevalence of schistosomiasis mekongi would be suppressed to a low level for a long time in a village further downstream when universal mass treatment is performed in villages further upstream simultaneously

Development of eosinophilic pneumonia from eosinophilic bronchiolitis without asthma: A case report

Eosinophilic bronchiolitis is a disease concept reported in Japan in 2001, that presents with bronchiolitis accompanied by eosinophilia in the blood and lungs. In 2013, hypereosinophilic obliterative bronchiolitis, as a group of disease presenting with eosinophilic bronchiolitis, was proposed in France. The relationship between eosinophilic bronchiolitis and other eosinophil-related diseases has not been clarified. Herein, we report the case of a 56-year-old female patient with eosinophilic bronchiolitis without asthma, which developed into eosinophilic pneumonia. Treatment with oral prednisone improved the respiratory function. According to the clinicopathological findings in this case, eosinophilic bronchiolitis may be a different disease from asthma

Platinum‐combination chemotherapy with or without immune‐checkpoint inhibitor in patients with postoperative recurrent non‐small cell lung cancer previously treated with adjuvant platinum‐doublet chemotherapy: A multicenter retrospective study

Abstract Background Rechallenge with platinum‐combination chemotherapy in patients with advanced non‐small cell lung cancer (NSCLC) after disease progression on platinum‐combination chemotherapy occasionally leads to a favorable response. The efficacy and safety of platinum‐combination chemotherapy with or without immune‐checkpoint inhibitor (ICI) for patients with recurrent NSCLC after surgery followed by adjuvant platinum‐doublet chemotherapy remains uncertain. Methods Patients who relapsed after surgery plus adjuvant platinum‐doublet chemotherapy and received platinum‐combination chemotherapy with or without ICI between April 2011 and March 2021 at four Nippon Medical School hospitals were retrospectively analyzed. Results Among 177 patients who received adjuvant platinum‐doublet chemotherapy after surgery, a total of 30 patients who received platinum‐combination rechemotherapy with or without ICI after relapse were included in this study. Seven patients received ICI‐combined chemotherapy. The median disease‐free survival (DFS) after surgery was 13.6 months. The objective response rate and disease‐control rate were 46.7% and 80.0%, respectively. The median progression‐free survival and overall survival were 10.2 and 37.5 months, respectively. Patients with longer DFS (≥12 months) had a better prognosis than others. The most common grade ≥3 toxicity associated with this treatment was neutropenia (33%). Grade ≥3 immune‐related adverse events were pneumonitis (14%) and colitis (14%). Treatment‐related deaths did not occur in this study. Conclusion Platinum‐combination chemotherapy with or without ICI for patients with postoperative recurrent NSCLC who previously received adjuvant platinum‐doublet chemotherapy was effective and safe. In particular, this therapy may be promising for patients with longer DFS