Summary Background Visceral leishmaniasis, also known on the Indian subcontinent as kala-azar, is a fatal form of leishmaniasis caused by the protozoan parasite Leishmania donovani and transmitted by the bites of the vector sandfly Phlebotomus argentipes . To achieve and sustain elimination of visceral leishmaniasis, the transmission potential of individuals exposed to L donovani from across the infection spectrum needs to be elucidated. The aim of this study was to evaluate the relative infectiousness to the sandfly vector of patients with visceral leishmaniasis or post-kala-azar dermal leishmaniasis, before and after treatment, and individuals with asymptomatic infection. Methods In this prospective xenodiagnosis study done in Muzaffarpur district of Bihar, India, we included patients with clinically confirmed active visceral leishmaniasis or post-kala-azar dermal leishmaniasis who presented to the Kala-Azar Medical Research Center. These participants received treatment for L donovani infection. We also included asymptomatic individuals identified through a serosurvey of 17 254 people living in 26 high-transmission clusters. Eligible participants were aged 12–64 years, were HIV negative, and had clinically or serologically confirmed L donovani infection. During xenodiagnosis, the forearms or lower legs of participants were exposed to 30–35 female P argentipes sandflies for 30 min. Blood-engorged flies were held in an environmental cabinet at 28°C and 85% humidity for 60–72 h, after which flies were dissected and evaluated for L donovani infection by microscopy and quantitative PCR (qPCR). The primary endpoint was the proportion of participants with visceral leishmaniasis or post-kala-azar dermal leishmaniasis, before and after treatment, as well as asymptomatic individuals, who were infectious to sandflies, with a participant considered infectious if promastigotes were observed in one or more individual flies by microscopy, or if one or more of the pools of flies tested positive by qPCR. Findings Between July 12, 2016, and March 19, 2019, we recruited 287 individuals, including 77 with active visceral leishmaniasis, 26 with post-kala-azar dermal leishmaniasis, and 184 with asymptomatic infection. Of the patients with active visceral leishmaniasis, 42 (55%) were deemed infectious to sandflies by microscopy and 60 (78%) by qPCR before treatment. No patient with visceral leishmaniasis was found to be infectious by microscopy at 30 days after treatment, although six (8%) were still positive by qPCR. Before treatment, 11 (42%) of 26 patients with post-kala-azar dermal leishmaniasis were deemed infectious to sandflies by microscopy and 23 (88%) by qPCR. Of 23 patients who were available for xenodiagnosis after treatment, one remained infectious ...

The biology of the fruit fly Bactrocera tau, an important horticultural pest, was studied under laboratory conditions at 25°C and 60–70% relative humidity on Cucurbita maxima. The duration of mating averaged 408.03 ± 235.93 min. After mating, the female fly had a preoviposition period of 11.7 ± 4.49 days. The oviposition rate was 9.9 ± 8.50 eggs and fecundity was 464.6 ± 67.98 eggs/female. Eggs were elliptical, smooth and shiny white, turning darker as hatching approached, and measured 1.30 ± 0.07 mm × 0.24 ± 0.04 mm. The chorion has polygonal microsculpturing and is species‐specific with polygonal walls. The egg period lasts for 1.3 ± 0.41 days. The duration of the larval period is 1.2 ± 0.42, 1.7 ± 0.48 and 4.0 ± 0.94 days for first, second and third instars, respectively. Pupation occurs in the sand or soil and pupal periods are 7.0 ± 0.47 days. The life cycle from egg to adult was completed in 14.2 ± 1.69 days; the longevity of mated females and males was 130.33 ± 14.18 and 104.66 ± 31.21 days, respectively. At least two to three generations were observed from June 2008 to June 2009.

This pilot project was preliminary and essential to a larger effort to define the ability of certain human-subject groups across the infection spectrum to serve as reservoirs of Leishmania donovani infection to sand flies in areas of anthroponotic transmission such as in Bihar state, India. This is possible only via xenodiagnosis of well-defined subject groups using live vector sand flies. The objective was to establish at the Kala Azar Medical Research Center (KAMRC), Muzaffarpur, Bihar, India, a self-sustaining colony of Phlebotomus argentipes (Annandale & Brunneti), closed to infusion with wild-caught material and certified safe for human xenodiagnosis. Prior to this endeavor, no laboratory colony of this vector existed in India meeting the stringent biosafety requirements of this human-use study. From March through mid-December, 2015, over 68,000 sand flies were collected in human dwellings and cattle sheds using CDC-type light traps over 254 nights. Blood-fed and gravid P. argentipes females were selected and placed individually in isoline-rearing vials for oviposition, and >2,500 egg clutches were harvested. Progeny were reared according to standard methods, providing a continuous critical mass of F1 males and females to stimulate social feeding behavior. With construction of a large feeding cage and use of a custom-made rabbit restrainer, the desired level of blood-feeding on restrained rabbits was achieved to make the colony self-sustaining and expand it to working level. Once self-sustaining, the colony was closed to infusion with wild-caught material and certified free of specific human pathogens.

No abstract

BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.