Naegleria fowleri is the only Naegleria spp. known to cause an acute, fulminant, and rapidly fatal central nervous system infection in humans called primary amebic meningoencephalitis (PAM). In 2016, a patient with suspected PAM was found in Zhejiang Province of China. The pathogen was identified by microscopic examination and PCR. The positive PCR products were sequenced and the sequences were aligned using the NCBI BLAST program. The homologous and phylogenetic analysis was conducted using MEGA 6 program. On microscopy of direct smears, motile cells with pseudopodia were observed, and the motion characteristics of the pseudopodia as well as the cell morphology suggested that the pathogens were amoeba trophozoites. Wright-Giemsa-stained smears showed amoeba trophozoites of various shapes, which measured 10-25μm in size; these were characterized by a prominent, centrally placed nucleolus and a vacuolated cytoplasm. PCR was negative for Entamoeba histolytica and Entamoeba dispar, but positive for Naegleria spp. and N. fowleri. The nucleotide sequences acquired in this study have been submitted to GenBank with accession numbers KX909928 and KX909927, respectively. The BLAST analysis revealed that the sequences of KX909928 and KX909927 had 100% similarity with the sequence of the N. fowleri gene (KT375442.1). Sequence alignment and the phylogenetic tree revealed that the N. fowleri collected in this study was classified as genotype 2 and was most closely related to Naegleria lovaniensis. This study confirmed N. fowleri as the agent responsible for the infection in this patient. PAM normally progresses rapidly and is generally universally fatal within a week. Unfortunately this patient died at 2 weeks after the onset of symptoms.
4 April 2018 in The American Journal of Tropical Medicine and Hygiene
To study the epidemiological distribution and the incident trends of imported malaria from 2012 to 2016 in Zhejiang Province, southeastern China, we collected data on malaria from the Information System for Parasitic Disease Control and Prevention. A total of 1,003 malaria cases were reported during 2012–2016, and all of these cases were imported. Plasmodium falciparum was the predominant species (76.3%) in Zhejiang Province. The percentage of Plasmodium vivax decreased from 33.6% to 8.1%, whereas the percentage of Plasmodium ovale and Plasmodium malariae increased. Most cases were male (89.8%), mostly in the age group of 21–50 years (82.6%). Businessmen (33.0%), workers (21.0%), farmers (18.8%), and overseas laborers (11.7%) were at high risk. The origin of the largest number of imported cases was Africa (89.5%), followed by Asia (10.0%) and Oceania (0.5%). The time interval from illness onset to confirmation was found to be significantly associated with the complications of patients. Out of 3,461 febrile individuals tested during reactive case detection, 10 malaria-positive individuals were identified. Effective surveillance and response system should be strengthened to prevent the reintroduction of malaria.
Anopheles sinensis is one of the most important malaria vectors in China and other Southeast Asian countries. High levels of resistance have been reported in this species due to the long-term use of insecticides, especially pyrethroids, for public health and agricultural purposes. Knockdown resistance (kdr) caused by a single base pair mutation in the gene encoding the sodium channel is strongly associated with pyrethroid insecticide resistance in many Anopheles mosquitoes. There are few methods currently available for detecting kdr mutations in An. sinensis. A novel AllGlo probe-based qPCR (AllGlo-qPCR) method was developed to screen for the predominant kdr mutations in An. sinensis mosquitoes from the Jiangsu Province. The results from AllGlo-qPCR, allele-specific PCR (AS-PCR), and TaqMan-MGB probe-based qPCR (TaqMan-qPCR) were compared. A comparative analysis of the equipment required, ease of use and cost of the available methods was also performed. Finally, the AllGlo-qPCR method was used to detect the frequencies of kdr mutations from the other four provinces in central China. Six kdr genotypes were detected in An. sinensis from the Jiangsu Province by DNA sequencing. The AllGlo-qPCR method detected all of the kdr genotypes with a high level of accuracy (97% sensitivity and 98% specificity). AllGlo-qPCR correctly determined the kdr genotypes of 98.73% of 158 An. sinensis samples, whereas TaqMan-qPCR and AS-PCR correctly identified 96.84% and 88.61% of mutations, respectively. Furthermore, the AllGlo-qPCR method is simpler to perform, requires less equipment, and exhibits a moderate expense cost comparing with the other tested methods of kdr mutation detection. Samples collected from four of the other provinces in central China showed a high frequency of kdr mutation in An. sinensis, as detected by the established AllGlo-qPCR method. The novel AllGlo-qPCR method developed for kdr mutation detection in An. sinensis exhibits greater specificity and sensitivity than currently available methods and is more cost-effective; therefore, it represents a useful tool for entomological surveillance.