Therapeutic efficacy of doxycycline in domestic cats naturally infected with Brugia malayi in field condition.

OBJECTIVE: The aim of this study was to evaluate the efficacy of oral doxycycline treatment for Brugia malayi as measured by microfilarial and filarial DNA clearance in naturally infected domestic cats. METHODS: This study included 8 domestic cats that lived with families that resided in Tak Bai District of Narathiwat Province, which is located in Southern Thailand. The study area is a known B. malayi endemic area. All study cats received doxycycline treatment doses by their respective owners according to a previously described protocol. Briefly, doxycycline (VibraVet@) was given orally once a day during weeks 1-4, 10-11, and 16-17. Blood collections were performed at baseline before treatment, and then every month for 12 months after the initial dose of doxycycline to assess microfilaraemia by Giemsa stain, and filarial DNA detection by high-resolution melt (HRM) real-time polymerase chain reaction (PCR). RESULTS: One month after the start of doxycycline treatment, five of eight cats were negative for microfilaraemia, and 4 of those were negative for filarial DNA. All cats receiving doxycycline treatment were negative for microfilaria by Giemsa stain, and for filarial DNA by HRM real-time PCR within 8 months after receiving the initial dose of doxycycline treatment. CONCLUSION: Administration of oral doxycycline to domestic cats naturally infected with B. malayi in disease endemic areas can significantly reduce microfilaraemia at 1 month and filarial DNA was undetectable by 8 months after the initial dose of doxycycline treatment. No recurrence of microfilaraemia or filarial DNA was observed in study cats at 1 year after the start of doxycycline. Included cats appeared to tolerate doxycycline (VibraVet@) well, with no adverse drug reactions reported by any study cat owner.

Balamuthia mandrillaris trophozoites ingest human neuronal cells via a trogocytosis-independent mechanism.

BACKGROUND: Environmental protozoa need an adaptation mechanism to survive drastic changes in niches in the human body. In the brain parenchyma, Balamuthia mandrillaris trophozoites, which are causative agents of fatal brain damage, must acquire nutrients through the ingestion of surrounding cells. However, the mechanism deployed by the trophozoites for cellular uptake remains unknown. METHODS: Amoebic ingestion of human neural cell components was investigated using a coculture system of clinically isolated B. mandrillaris trophozoites and human neuroblastoma SH-SY5Y cells. Cell-to-cell interactions were visualized in a three-dimensional manner using confocal and holotomographic microscopes. RESULTS: The B. mandrillaris trophozoites first attached themselves to human neuroblastoma SH-SY5Y cells and then twisted themselves around the cytoplasmic bridge. Based on fluorescence-based cell tracking, the B. mandrillaris trophozoites then inserted invadopodia into the cytoplasm of the human cells. Subsequently, the human protein-enriched components were internalized into the trophozoites in the form of nonmembranous granules, whereas the human lipids were dispersed in the cytoplasm. Intervention of trogocytosis, a process involving nibbling on parts of the target cells, failed to inhibit this cellular uptake. CONCLUSIONS: Human cell ingestion by B. mandrillaris trophozoites likely differs from trogocytosis, suggesting that a pathogen-specific strategy can be used to ameliorate brain damage.

A novel droplet digital polymerase chain reaction for diagnosis of Pneumocystis pneumonia (PCP)-a clinical performance study and survey of sulfamethoxazole-trimethoprim resistant mutations.

Objectives To determine the performance of droplet digital polymerase chain reaction (ddPCR) assays in diagnosing Pneumocystis pneumonia (PCP), and to survey the sulfamethoxazole-trimethoprim (SMX-TMP) resistant mutations in our PCP cohort. Methods A prospective study was conducted from January 2017 to June 2018. Adult immunocompromised subjects with pneumonia were enrolled. Bronchoalveolar lavage fluid samples were obtained for standard microscopic testing and ddPCR to quantify the Pneumocystis MSG gene. DHPS and DHFR gene sequencings were performed to detect SMX-TMP resistance. Results Of 54 subjects, 12 had definite PCP, 7 had probable PCP, and 35 were non-PCP. In the PCP cohort, 10 (53%) had HIV infections. Using a cutoff value of ≥ 1.94 copies/µL, the ddPCR exhibited an overall sensitivity of 91.7% (61.5-99.8%) and specificity of 88.1% (74.4-96%). It showed a better performance when different cutoff values were used in subjects with HIV (≥ 1.80 copies/µL) and non-HIV (≥ 4.5 copies/µL). ROC curves demonstrated an AUC of 0.80 (95% CI, 0.56-1.0) for the HIV group, and 0.99 (95% CI, 0.95-1.0) for the non-HIV group. Of 16 PCP samples tested for DHPS- and DHFR-mutations, only DHPS mutations were detected (2). Most of the subjects, including those with DHPS mutations, demonstrated favorable outcomes. Conclusions The ddPCR exhibited a satisfactory diagnostic performance for PCP. Based on very limited data, the treatment outcomes of PCP did not seem to be affected by the DHPS mutations.

The first case report of subcutaneous dirofilariasis caused by Dirofilaria repens in Thailand.

Dirofilariasis is a rare zoonotic disease which is commonly caused by two Dirofilaria species; Dirofilaria immitis and Dirofilaria repens. Humans are accidental dead-end hosts of the parasites, and the infection is mainly asymptomatic. Here, we report the case of a 54-year-old Thai woman who experienced a painful left shoulder nodule and eosinophilia for 1 month. An excisional biopsy of the nodule revealed a degenerated filarial nematode compatible with adult females of the Dirofilaria species. Molecular identification of the partial 12 mt rRNA gene of the worm confirmed that the causative species was D. repens, a zoonotic filariasis that causes subcutaneous dirofilariasis in dogs and cats. To the best of our knowledge, this was the first reported case of subcutaneous dirofilariasis caused by D. repens in Thailand. This increased concerns about zoonotic filariasis from natural animal reservoirs in Thailand.