scholarly journals Complete Life Cycle of Trypanosoma thomasbancrofti, an Avian Trypanosome Transmitted by Culicine Mosquitoes

2021 ◽  
Vol 9 (10) ◽  
pp. 2101
Author(s):  
Magdaléna Fialová ◽  
Anežka Santolíková ◽  
Anna Brotánková ◽  
Jana Brzoňová ◽  
Milena Svobodová
Keyword(s):  
Life Cycle ◽  
Infection Rate ◽  
Culex Pipiens ◽  
Life Cycles ◽  
Protozoan Parasites ◽  
Infection Rates ◽  
Experimental Transmission ◽  
Complete Life Cycle ◽  
High Infection ◽  
Avian Populations

Avian trypanosomes are cosmopolitan and common protozoan parasites of birds; nevertheless, knowledge of their life cycles and vectors remains incomplete. Mosquitoes have been confirmed as vectors of Trypanosoma culicavium and suggested as vectors of T. thomasbancrofti; however, transmission has been experimentally confirmed only for the former species. This study aims to confirm the experimental transmission of T. thomasbancrofti to birds and its localization in vectors. Culex pipiens were fed on blood using four strains of T. thomasbancrofti, isolated from vectors and avian hosts; all strains established infections, and three of them were able to develop high infection rates in mosquitoes. The infection rate of the culicine isolates was 5–28% for CUL15 and 48–81% for CUL98, 67–92% for isolate OF19 from hippoboscid fly, while the avian isolate PAS343 ranged between 48% and 92%, and heavy infections were detected in 90% of positive females. Contrary to T. culicavium, trypanosomes were localized in the hindgut, where they formed rosettes with the occurrence of free epimastigotes in the hindgut and midgut during late infections. Parasites occurred in urine droplets produced during mosquito prediuresis. Transmission to birds was achieved by the ingestion of mosquito guts containing trypanosomes and via the conjunctiva. Bird infection was proven by blood cultivation and xenodiagnosis; mature infections were present in the dissected guts of 24–26% of mosquitoes fed on infected birds. The prevalence of T. thomasbancrofti in vectors in nature and in avian populations is discussed in this paper. This study confirms the vectorial capacity of culicine mosquitoes for T. thomasbancrofti, a trypanosome related to T. avium, and suggests that prediuresis might be an effective mode of trypanosome transmission.

The Susceptibility of Autogenous and Anautogenous Races of Culex pipiens to Infection with Avian Malaria (Plasmodium relictum)

Parasitology ◽  
1934 ◽  
Vol 26 (4) ◽  
pp. 512-522 ◽  
Author(s):  
P. Tate ◽  
M. Vincent
Keyword(s):  
Infection Rate ◽  
Culex Pipiens ◽  
Avian Malaria ◽  
Infection Rates ◽  
Chronic Infections ◽  
Seasonal Influence ◽  
Plasmodium Relictum ◽  
The Difference ◽  
Different Strains

1. Anautogenous English and autogenous Greek, Hungarian, Maltese and cross-bred strains of C. pipiens were infected with an Algerian and a German strain of P. relictum.2. The different strains of C. pipiens behaved similarly as regards susceptibility and transmission towards the same strain of P. relictum.3. The two strains of malaria differ in the infection rate produced in mosquitoes. The Algerian strain produces an infection rate of about 89 per cent., while that of the German strain is only about 43 per cent.4. The difference in the infection rates of the two strains is not due merely to differences in the number of gametocytes formed.5. In general C. pipiens fed on birds infected with the Algerian strain of malaria became more heavily infected than those fed on birds infected with the German strain.6. C. pipiens were infected in some cases by feeding on birds with chronic infections of the Algerian strain of P. relictum, but not when fed on birds with chronic infections of the German strain.7. No seasonal influence was found as regards the infection of C. pipiens by P. relictum.8. The Algerian strain of malaria was successfully transmitted by English, Greek, Hungarian, Maltese and Greek-Hungarian strains of C. pipiens, and the German strain of malaria by English, Greek, Maltese and Greek-English strains of C. pipiens.

scholarly journals Waning of Measured Influenza Vaccine Effectiveness Over Time: The Potential Contribution of Leaky Vaccine Effect

2020 ◽  
Vol 71 (10) ◽  
pp. e633-e641
Author(s):  
Jerome I Tokars ◽  
Manish M Patel ◽  
Ivo M Foppa ◽  
Carrie Reed ◽  
Alicia M Fry ◽  
...  
Keyword(s):  
Influenza Vaccine ◽  
Infection Rate ◽  
Vaccine Effectiveness ◽  
Potential Contribution ◽  
Infection Rates ◽  
High Infection ◽  
Waning Immunity ◽  
Seasonal Infection ◽  
Incident Cases ◽  
Vaccine Effect

Abstract Background Several observational studies have shown decreases in measured influenza vaccine effectiveness (mVE) during influenza seasons. One study found decreases of 6–11%/month during the 2011–2012 to 2014–2015 seasons. These findings could indicate waning immunity but could also occur if vaccine effectiveness is stable and vaccine provides partial protection in all vaccinees (“leaky”) rather than complete protection in a subset of vaccinees. Since it is unknown whether influenza vaccine is leaky, we simulated the 2011–2012 to 2014–2015 influenza seasons to estimate the potential contribution of leaky vaccine effect to the observed decline in mVE. Methods We used available data to estimate daily numbers of vaccinations and infections with A/H1N1, A/H3N2, and B viruses. We assumed that vaccine effect was leaky, calculated mVE as 1 minus the Mantel-Haenszel relative risk of vaccine on incident cases, and determined the mean mVE change per 30 days since vaccination. Because change in mVE was highly dependent on infection rates, we performed simulations using low (15%) and high (31%) total (including symptomatic and asymptomatic) seasonal infection rates. Results For the low infection rate, decreases (absolute) in mVE per 30 days after vaccination were 2% for A/H1N1 and 1% for A/H3N2and B viruses. For the high infection rate, decreases were 5% for A/H1N1, 4% for A/H3, and 3% for B viruses. Conclusions The leaky vaccine bias could account for some, but probably not all, of the observed intraseasonal decreases in mVE. These results underscore the need for strategies to deal with intraseasonal vaccine effectiveness decline.

scholarly journals Are countries precautionary actions against COVID-19 effective? An assessment study of 175 countries worldwide

2020 ◽  
Author(s):  
Thamir M Alshammari ◽  
Khalidah Alenzi ◽  
Fatemah Alnofal ◽  
Ghada Fradees ◽  
Ali Altebainawi
Keyword(s):  
Health Care ◽  
Severe Acute Respiratory Syndrome ◽  
Observational Study ◽  
Infection Rate ◽  
Infection Rates ◽  
Financial Systems ◽  
School Closures ◽  
Assessment Study ◽  
High Infection ◽  
The Relationship

Background The Coronavirus Disease 2019 (COVID-19) pandemic has affected many countries negatively, particularly in terms of their health care and financial systems. Numerous countries have attempted to employ precautions to address this pandemic. Objective This study was aimed at exploring and assessing the precautionary actions taken by 175 countries on six continents to prevent the spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Methods An observational study was conducted based on data collected during the period from December 31, 2019, until the end of April 2020. Several data were extracted, including information related to the date of the first reported case of SARS-CoV-2, total confirmed cases, total active cases, and more. In addition, seven validated indicators were used to assess the countries preparedness and precautionary actions. Results A total of 175 countries were included in the study. The total COVID-19 infection rate increased exponentially and rapidly in North America and Europe from March to April. The application of the precautions (indicators) varied between countries. School closures, quarantines and curfews were the most applied indicators among all countries. As for the relationship between the indicators and their effects on the infection rate, Italy and Spain were the top countries in Europe and adopted all indicators. Nevertheless, they faced high infection rates: 239,639 and 205,463 COVID-19 cases in Spain, and Italy, respectively. Conclusion The precautionary actions might have played a role in limiting the spread of COVID-19 in several countries. However, many countries did not benefit from applying these indicators.

scholarly journals Trematodiasis occurrence in cattle along the Progo River, Yogyakarta, Indonesia

2019 ◽  
Vol 12 (4) ◽  
pp. 593-597 ◽  
Author(s):  
Korbinianus Feribertus Rinca ◽  
Joko Prastowo ◽  
Dwi Priyo Widodo ◽  
Yudhi Ratna Nugraheni
Keyword(s):  
Infection Rate ◽  
High Rate ◽  
Multiple Infections ◽  
Trematode Species ◽  
Infection Rates ◽  
Fecal Samples ◽  
Sedimentation Technique ◽  
High Infection ◽  
Fasciola Spp ◽  
Trematode Parasites

Aim: This study aimed to measure the occurrence of trematodiasis in cattle along the Progo River, a district of Yogyakarta, Indonesia. The findings help to establish the magnitude of the disease and encourage prevention and treatment of this condition. Materials and Methods: Trematode eggs were extracted from 100 fecal samples collected from cattle. The eggs were examined using the sedimentation technique, and the method of Parfitt and Banks was used to differentiate Paramphistomum spp. eggs from Fasciola spp. eggs. Results: The infection rate of trematode parasites was 50%. Cattle experienced multiple infections of both Paramphistomum spp. and Fasciola spp., as well as single infections of one species or the other. All breeds were vulnerable to infections of both trematode species, although different cattle breeds, including Peranakan Ongole crossbreeds, Simmental crossbreeds, and Limousin crossbreeds, showed differences in infection rate. The highest rate of infection with Paramphistomum spp. (15.78%) occurred in the Simmental crossbreeds. The highest rate of infection (31.57%) with Fasciola spp. was in the Peranakan Ongole crossbreeds. Multiple infections of both Paramphistomum spp. and Fasciola spp. were highest in Simmental crossbreed cattle (28.97%). Conclusion: The high infection rates of trematode parasites found in fecal samples, particularly of Fasciola spp., indicate that the cattle along the Progo River in Indonesia experience a high rate of trematodiasis disease.

The regulation of populations ofOstertagia ostertagiin calves

Parasitology ◽  
1970 ◽  
Vol 61 (3) ◽  
pp. 435-447 ◽  
Author(s):  
J. F. Michel
Keyword(s):  
Infection Rate ◽  
Small Proportion ◽  
Post Mortem ◽  
Fourth Stage ◽  
Infection Rates ◽  
Ostertagia Ostertagi ◽  
High Infection ◽  
The Relationship

The course of the worm burdens of calves infected daily with larvae ofOstertagia ostertagiat five different rates was studied by making post-mortem worm counts on groups of calves killed after experiencing infection for different periods of time.The relationship between worm numbers and infection rates together with evidence that a turnover of worms occurred, led to the conclusion that burdens of adult worms were regulated primarily by a loss of worms at a rate proportional to the number present.Further, estimates based on the number of developing fourth-stage larvae indicated that the proportion of the larvae administered which became established decreased gradually as the experiment progressed.At very low infection rates, the rate of turnover of the worms was slower than at high infection rates but in all groups it remained constant through the 6 months duration of the experiment.The development of a small proportion of the larvae administered was arrested at the early fourth stage. At the highest infection rate used, the proportion of worms that became inhibited was somewhat greater.

An Approach to the Statistical Analysis of Peritonitis Data from Patients on CAPD

1980 ◽  
Vol 1 (1_suppl) ◽  
pp. 29-33 ◽  
Author(s):  
Paul Corey
Keyword(s):  
Median Time ◽  
Infection Rate ◽  
Infection Rates ◽  
Calendar Time ◽  
Risk Of Failure ◽  
High Infection ◽  
Lower Infection ◽  
Males And Females ◽  
Lower Infection Rate ◽  
Increase In Risk

1. The distribution of peritoneal infections at any time during the CAPD program is random. This does not necessarily mean that the patients with high infection rates do not have identifiable characteristics that could be used in patient selection, but rather that these characteristics themselves could be randomly distributed among the patients. 2. The median time to first infection is about 260 days and is the same for males and females. 3. The median time between first and second infection is approximately 300 days. 4. The time to first infection and the infection rate per patient are negatively related to the calendar time of entry into the CAPD program, i.e., patients who entered the program later, tended to experience a lower infection rate. 5. The increase in risk of failure on the CAPD program for patients who have at least one infection in the first 90 to 150 days in the program is greater than three. 6. The increase in risk of failure on the CAPD program increases by at least 3% per annum, i.e., for each additional year on CAPD, the risk of failure increases over that of the previous year by 3%.

Life cycle of the temporary fish parasite,Gnathia pilosus(Crustacea: Isopoda: Gnathiidae) from the east coast of South Africa

2009 ◽  
Vol 89 (7) ◽  
pp. 1331-1339 ◽  
Author(s):  
Kerry A. Hadfield ◽  
Nico J. Smit ◽  
Annemarié Avenant-Oldewage
Keyword(s):  
Life Cycle ◽  
South African ◽  
East Coast ◽  
Life Cycles ◽  
Larval Stages ◽  
Second Stage ◽  
Complete Life Cycle ◽  
Gnathiid Isopod ◽  
Blood Meals ◽  
Main Factor

The life cycle of the South African gnathiid isopod,Gnathia pilosus, was studied using the common east coast tidal pool fish,Scartella emarginataandAntennablennius bifilumas hosts. Laboratory studies observing the feeding ecology of these temporary ectoparasites determined that the second and third unfed larval stages (zuphea larvae 2 and 3) took an average of 3 hours 52 minutes and 4 hours 19 minutes to feed respectively. After feeding, the second stage fed larvae (praniza 2) took 35 days to moult into the third zuphea form. Male and female praniza 3 larvae could be discerned before their final moults into adults which took place approximately 42 and 48 days respectively after their blood meals. Fertilization occurred within 24 hours after the female had completed her moult. It was thus estimated that the complete life cycle from the first larval stage to adult took between 134 to 140 days in water temperatures ranging between 20°C and 25°C. The length for this life cycle is unexpectedly long for gnathiids living in subtropical waters and may indicate that water temperature is not always the main factor in determining the duration of gnathiid life cycles.

Infestation of littorinids by larval Digenea around a small fishing port

Parasitology ◽  
1985 ◽  
Vol 90 (2) ◽  
pp. 277-287 ◽  
Author(s):  
P. M. Matthews ◽  
W. I. Montgomery ◽  
R. E. B. Hanna
Keyword(s):  
Infection Rate ◽  
Direct Relationship ◽  
Snail Host ◽  
Negative Association ◽  
Helminth Species ◽  
High Infection Rate ◽  
Infection Rates ◽  
Snail Infection ◽  
High Infection ◽  
Raw Fish

Larval Digenea infecting Littorina rudis, L. littorea and L. obtusata around Portavogie harbour, Co. Down, were examined. High levels of infection were found among the littorinids collected from sites on the harbour shore, though levels of infection varied somewhat with position on the shore. There was a direct relationship between size of the snail host and likelihood of infection. There was a negative association between certain pairs of helminth species in the same host, particularly where the rediae of Cryptocotyle lingua or Himasthla sp. were involved. Infection rates in gastropods declined away from the harbour and it is concluded that the high infection rate centres around the harbour were probably due to the increased concentration of definitive hosts, mainly seagulls, attracted to this area by dumping of raw fish offal. The infection of Pholis gunnellus with the metacercariae of C. lingua was also examined. Older fish were more heavily infected than younger fish but no direct relationship was found between high snail infection rates and high P. gunnellus infection rates.

MERGERS AND ACQUISITIONS AND THEIR CORRELATION WITH THE LIFE CYCLES OF MEMBER COMPANIES ON THE EXAMPLE OF THE RUSSIAN MARKET 2017–2019

2020 ◽  
Vol 1 (10) ◽  
pp. 26-35
Author(s):  
E. A. SHUBINA ◽  
◽  
Yu. A. KOMAROVSKY ◽  
A. V. MERKUSHEV ◽  
◽  
...  
Keyword(s):  
Life Cycle ◽  
Mergers And Acquisitions ◽  
Life Cycles ◽  
Russian Market

The article is devoted to the study of the largest mergers and acquisitions (M&A, “Mergers & Acquisitions”) in Russia for 2017–2019. (the acquired block of shares is not less than 99%). The concept of life cycles of organizations and theoretical aspects of mergers and acquisitions are described. The stages of the life cycle of the merged and reorganized companies, the goals of mergers and acquisitions, depending on the stages of the life cycle are analyzed.

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