Number Of Previous Infections Research Articles

The severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) omicron sub-variants in Bangladesh cause mild COVID-19 and associate with similar antibody responses irrespective of natural infection or vaccination history

ObjectiveGenomic surveillance and seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) in Bangladesh is paramount for COVID-19 pandemic preparedness yet lagging the high-income countries due to limited resources. MethodsSARS-CoV-2 variants, COVID-19 symptoms, and serology were prospectively evaluated in a cross-sectional study of Bangladeshi adults testing RT-PCR positive in 2021 and 2022. ResultsSARS CoV-2 Omicron variants of asymptomatic or mild COVID-19 in 2022 replaced Delta variant infections requiring hospitalization and oxygen support. The omicron XBB became predominant in July 2022 and associated with cough, headache or body ache and loss of smell; 47 of 68 (69 %), 30 of 68 (44 %) and 27 of 68 (40 %) respectively at higher frequency than BA.1/BA.2; 16 of 88 (18 %), 13 of 88 (15 %) and 0 of 88 (0 %) p < 0.01, p < 0.01 and p < 0.0001. Linear regression analysis reveals no associations between the number of previous infections and the number of symptoms, r = −0.084, p = 0.68. The anti-nucleoprotein (N)-protein IgG post COVID-19 and anti-Spike (S) protein IgG post-COVID-19 vaccination were similar between BA.2, BA.4/BA.5 and XBB and significantly lower than the levels in delta variant infections (p < 0.001). ConclusionsOmicron XBB subvariants emerged in Bangladesh two months prior to previous reports and include unique patterns of S-protein mutations not assigned in PANGO lineage. The SARS CoV-2 omicron break-through infections persist in the presence of sustained antibody responses and vaccinations, underscoring the importance of molecular surveillance in low-income countries.

Systemic Review on the Pathogenicity of Plasmodium berghei in the Liver and Spleen of the Experimental Mice

Malaria is still one of the most prevalent tropical and parasitic diseases throughout the world representing a global health concern. Even with all efforts to restrict disease transmission and national malaria control programs, malaria infection continues to cause considerable morbidity and mortality in resource-poor countries. Malaria infection occurs in two stages, the Exoerythrocytic and Erythrocytic stage. The exact biology of malaria parasite in human hosts is likely relatively similar, with the main differences being attributable to the human immune response, the number of previous infections and the exposure profile. The disease severity can be determined by the balance between the pro-inflammatory and anti-inflammatory cytokines. Although, research about the clinical characterization and histology of malaria has shown some information regarding the pathogenesis, the actual mechanisms by which malaria parasites produce severe disease, the immunity defends against infection is remained unknown. Studies in animal models can reveal details about the processes of severe malaria infection and human defense mechanisms. Because of its similarities to the Plasmodium species that cause human malaria, Plasmodium berghei is used as a model organism for the experimental research. In addition, of affecting the central nervous system, Plasmodium berghei infection in the Swiss Webster mouse causes systemic damage, and affects numerous organs including the liver and lymphoid organs. The infected spleen demonstrations includethe splenomegaly, re-modelling and other basic changes consist of the red pulp’s expansion, marginal zone’s slight damage, enlarged vasculature and the barrier cells activities. Moreover, the liver shows hyperplastic Kupffer cells, fatty change, portal tract inflammation, cholestasis, liver cell necrosis, sequestration of Parasitized Red Blood Cells (PRBCs) and deposition of hemozoin pigments.

Sera selected from national STI surveillance system shows Chlamydia trachomatis PgP3 antibody correlates with time since infection and number of previous infections.

BackgroundSeroprevalence surveys of Chlamydia trachomatis (CT) antibodies are promising for estimating age-specific CT cumulative incidence, however accurate estimates require improved understanding of antibody response to CT infection.MethodsWe used GUMCAD, England’s national sexually transmitted infection (STI) surveillance system, to select sera taken from female STI clinic attendees on the day of or after a chlamydia diagnosis. Serum specimens were collected from laboratories and tested anonymously on an indirect and a double-antigen ELISA, both of which are based on the CT-specific Pgp3 antigen. We used cross-sectional and longitudinal descriptive analyses to explore the relationship between seropositivity and a) cumulative number of chlamydia diagnoses and b) time since most recent chlamydia diagnosis.Results919 samples were obtained from visits when chlamydia was diagnosed and 812 during subsequent follow-up visits. Pgp3 seropositivity using the indirect ELISA increased from 57.1% (95% confidence interval: 53.2–60.7) on the day of a first-recorded chlamydia diagnosis to 89.6% (95%CI: 79.3–95.0) on the day of a third or higher documented diagnosis. With the double-antigen ELISA, the increase was from 61.1% (95%CI: 53.2–60.7) to 97.0% (95%CI: 88.5–99.3). Seropositivity decreased with time since CT diagnosis on only the indirect assay, to 49.3% (95%CI: 40.9–57.7) two or more years after a first diagnosis and 51.9% (95%CI: 33.2–70.0) after a repeat diagnosis.ConclusionSeropositivity increased with cumulative number of infections, and decreased over time after diagnosis on the indirect ELISA, but not on the double-antigen ELISA. This is the first study to demonstrate the combined impact of number of chlamydia diagnoses, time since diagnosis, and specific ELISA on Pgp3 seropositivity. Our findings are being used to inform models estimating age-specific chlamydia incidence over time using serial population-representative serum sample collections, to enable accurate public health monitoring of chlamydia.

Health impact and cost-effectiveness of a domestically-produced rotavirus vaccine in India: A model based analysis.

BackgroundCurrently, Indian officials are incorporating a domestically manufactured rotavirus vaccine (based on the 116E rotavirus strain) into the country’s universal immunization program; this vaccine will cost significantly less than western rotavirus vaccines. Here, we examine the public health impact, cost, and cost-effectiveness of universal vaccination in India using the 116E vaccine. This work will allow comparison of universal 116E vaccination with other approaches to child mortality reduction, shed light on the future burden of rotavirus disease in India, and help stakeholders understand future resource needs.MethodsUsing information from published literature, we developed a dynamic simulation model of rotavirus transmission, natural history, and related utilization among Indian infants followed until age five. Infection risk depended on the degree of viral shedding in the population. Infection risk and severity were influenced by age, number of previous infections, and vaccination history. Probabilities of inpatient and outpatient health services utilization depended on symptom severity. With the model, we compared a strategy of nationwide 116E vaccination to one of no vaccination. Costs were considered from the perspective of all payers (including families) and from the societal perspective.ResultsWe estimated that an established 116E vaccination program would reduce symptomatic rotavirus infection by 13.0%, while reducing population-wide rotavirus mortality by 34.6% (over 34,000 lives annually). Rotavirus outpatient visits would decline by 21.3%, and hospitalization would decline by 28.1%. The cost per disability-adjusted life year (DALY) averted was estimated at 3,429 Rupees (approximately $56). Predicted mortality reduction in children born during the first five years of vaccination implementation was nearly identical to that in children born in later years (34.4% versus 34.6%).Conclusions116E vaccination of Indian infants would likely substantially reduce rotavirus-related morbidity, mortality, and utilization at a cost considered highly cost-effective by standard criteria. Nearly the entire mortality reduction benefit of vaccination was attributable to direct protection of those vaccinated, as opposed to indirect “herd immunity” effects.

T follicular helper cells regulate the activation of B lymphocytes and antibody production during Plasmodium vivax infection.

Although the importance of humoral immunity to malaria has been established, factors that control antibody production are poorly understood. Follicular helper T cells (Tfh cells) are pivotal for generating high-affinity, long-lived antibody responses. While it has been proposed that expansion of antigen-specific Tfh cells, interleukin (IL) 21 production and robust germinal center formation are associated with protection against malaria in mice, whether Tfh cells are found during Plasmodium vivax (P. vivax) infection and if they play a role during disease remains unknown. Our goal was to define the role of Tfh cells during P. vivax malaria. We demonstrate that P. vivax infection triggers IL-21 production and an increase in Tfh cells (PD-1+ICOS+CXCR5+CD45RO+CD4+CD3+). As expected, FACS-sorted Tfh cells, the primary source of IL-21, induced immunoglobulin production by purified naïve B cells. Furthermore, we found that P. vivax infection alters the B cell compartment and these alterations were dependent on the number of previous infections. First exposure leads to increased proportions of activated and atypical memory B cells and decreased frequencies of classical memory B cells, whereas patients that experienced multiple episodes displayed lower proportions of atypical B cells and higher frequencies of classical memory B cells. Despite the limited sample size, but consistent with the latter finding, the data suggest that patients who had more than five infections harbored more Tfh cells and produce more specific antibodies. P. vivax infection triggers IL-21 production by Tfh that impact B cell responses in humans.

Association of serum antibodies with protection against rotavirus infection and disease in South Indian children

Serum antibodies play an important role in natural protection from rotavirus infection and disease, but conflicting estimates of association have emerged from epidemiological studies in different geographical settings. In this study, we aim to assess the relationship between pre-existing serum immunoglobulin (Ig)G and IgA titers with protection against rotavirus infection and disease in a birth cohort of Indian children. Children were recruited at birth and followed up for 36 months. Stool samples were collected every 2 weeks and during episodes of diarrhea and serum samples were obtained at least every 6 months. The incidence rate of rotavirus infection and diarrhea was 0.9 (95% CI: 0.88, 0.99) and 0.2 (95% CI: 0.19, 0.25) episodes per child year, respectively. The risk of rotavirus infection and diarrhea decreased with age, while antibody titers (IgG and IgA) increased with age. After adjusting for age and number of previous infections, higher levels of IgG and IgA were independently associated with reduced risk of rotavirus infection. However, we did not find a clear association of IgG or IgA with rotavirus diarrhea risk or a threshold level of protection. The study supports a correlation of serum antibodies in reducing the risk of rotavirus infections, however the potential of serum antibody titer as a correlate of protection is not clear for children in lower income settings.

Public health impact and cost effectiveness of mass vaccination with live attenuated human rotavirus vaccine (RIX4414) in India: model based analysis

Objectives To examine the public health impact of mass vaccination with live attenuated human rotavirus vaccine (RIX4414) in a birth cohort in India, and to estimate the cost effectiveness and...

Choosing between public and private health-care: A case study of malaria treatment in Brazil

Individuals infected with malaria may be treated either in the public sector or in a private clinic. Private treatment is better, but expensive. Using micro-level data from a colonization project in Brazil, we estimate the factors that determine an individual's choice between the two sectors. Private treatment is (strongly) price sensitive and (weakly) wealth sensitive. Rural individuals are more likely to choose private treatment, but long distances to the treatment source deter private treatment. Individuals belonging to small, literate households are more likely to choose private treatment. Gender, age, and number of previous infections are unimportant. Policy implications are discussed.

Cell-mediated immune response in gonococcal infection.

A peripheral leukocyte migration inhibition test has been used to demonstrate cellular immunity to a protein component of Neisseria gonorrhoeae. Human leukocytes served as effector cells in an agarose method to distinguish antigen-sensitive from nonsensitive individuals. Leukocytes, preincubated with antigen, were placed in wells in medium 199 agarose. After 18 h of incubation the migration index was calculated by dividing the area of migration of cells preincubated with antigen by the area of migration of the control cells. Significant migration inhibition was demonstrated for 16 of the 30 patients with uncomplicated gonorrhoea. Maximum inhibition was obtained 7-10 days following the onset of symptoms and the duration of the response varied from 14 to more than 40 days. There was a statistically significant positive correlation between the number of previous infections and migration inhibition. A control group, which included individuals with Neisseria meningitidis infection, showed an insignificant response to this gonococcal antigen. Although these results indicate the presence of cell-mediated immunity, the significance of this response in the protection of the host or in the pathogenesis of gonococcal disease has yet to be determined.

The response of rabbits to repeated infections withFasciola hepatica

Rabbits developed a partial resistance to infection withFasciola hepatica following two previous infections of four weeks duration, which had been terminated by chemotherapy. Serum glutamic dehydrogenase assays 4–5 weeks post infection correlated negatively with both the number of flukes derived from the challenge infection and with the number of previous infections. Peripheral eosinophil counts did not give similar correlations.

Treatment of uncomplicated urinary tract infection in non-pregnant women

Summary A study of placebo treatment of acute symptomatic urinary tract infection in non-pregnant women showed that about 80% obtained sterile urine spontaneously within 5 months. About one-half of these had recurrent infection within a year. Antimicrobials produced a high immediate cure rate, but only 45% maintained sterile urine for 2 years. The recurrence rate was highest during the first 2 months after treatment, and thereafter nearly constant during the subsequent 20 months. Twenty-nine percent of recurrences were recrudescences and 71% reinfections. About one-sixth of the patients had a very high recurrence rate, 2·6 infections/year, as compared with 0·32/year in the remainder. Nearly all of these patients had their first recurrence within 5 months of the initial treatment. The probability of recurrence increased with the number of previous infections. Some patients, however, after a period with many recurrences, showed a remarkable decrease in recurrence rate. If the aim of treatment is to keep periods of bacteriuria to a minimum, it is necessary to do frequent urine cultures for at least 6 months after elimination of bacteriuria.

Venereal Disease Contacts of Merchant Seamen

T HE Division of Foreign Quarantine, in cooperation with the then Division of Venereal Disease, Public Health Service, conducted a study of venereal disease contacts among merchant seamen during a 6-month period beginning June 1, 1951, and ending November 30, 1951. The purpose of the study was to determine which seaports of the world are the principal foci of infection. Each major quarantine station in the United States, Hawaii, and Puerto Rico participated. A contact study report was completed for each seaman (citizen or alien) who had been treated for venereal disease during the voyage to the United States or who had clinical symptoms of venereal disease and was so diagnosed upon arrival. The report form included the name and nationality of vessel, date of arrival, nationality of the seaman, venereal disease for which the seaman was treated, number of previous infections, ports where sex contacts occurred, number of days of shore leave, and number and type of different sex partners. In the 6-month period of the study, 2,426 infected seamen reported 4,364 sex contacts in ports throughout the world. This represents a contact index of 1.80. Of the total number of infected seamen, 2,052 (84.6 percent) were treated for venereal disease en route to the United States, and 381 (15.7 percent) were treated upon arrival. (The total exceeds 100 percent because some men were treated both en route and upon arrival.) Patients with gonorrhea accounted for 1,953 of the venereal infections and comprised 80.5 percent of the total 2.426. Based on current venereal disease rates, the 1,953 cases of gonorrhea represent the morbidity which might be expected from a population of 1,286,000 United States citizens annually. Similarly, the 225 cases of syphilis are equal to the annual morbidity of infectious cases to be expected among 1,086,000 United States citizens. Although some 30 countries of residence were represented, 64 percent of the infected seamen were Americans. Fifty-one percent of the patients reported they had had previous infections. The nmimber of infected seamen reported to quarantine stations in the various geographic areas are as follows: east coast, 982; gulf coast, 298; west coast, 1,057; Hawaii, 60; and Puerto Rico, 29. The nationalities of infected seamen, arranged in descending order of frequency, were: American, Norwegian, British, Danish, Swedish, Canadian, Dutch, Greek, German, Honduran, Finnish, French, Cuban, and Spanish. Each of these nationalities included 10 or more infected. seamen. Table 1 lists the leading ports of exposure throughout the world and shows the number of seamen infect;ed and the number of exposures. The total nurnber of infected seamen and contacts also are shown for each port and continent. Since some men were exposed in more than one port, the sum of infected men in this table exceeds the total of 2,426. Table 2 indicates the number of contacts by geographic area of exposure and type of contact. Pickup-no-fee is reported more often than any other type of contact in ports of the United States and Europe. On the other hand, house prostitute is reported more often than other types of contacts in Mexico, Japan, West Indies, Central America, South America, India, and Africa. Of the total contacts in all ports, almost half (47.2 percent) were reported as house prostitute. The remaining types of contacts were distributed among streettwalker Dr. Stuart is health program officer and Mr. Joyce is a statistician with the Venereal Disease Branch, Division of Special Health Services, Public Health Service.