Biomedical subjects

K C Hyams

Publications and source records attributed to K C Hyams.

At least 55 records · Page 3Linked to original sources

PubMed1996

A waterborne outbreak of hepatitis E virus transmission in southwestern Vietnam.

A hepatitis outbreak affecting primarily adults occurred in southwestern Vietnam, along the Hau river bordering Cambodia, in June and July 1994. One month after the outbreak, sera and epidemiologic information were collected from 150 subjects: 50 patient cases, 50 matched, healthy community controls, and 50 geographic controls living 50 km upriver. The prevalence of immunoglobulin G (IgG) to hepatitis E virus (HEV) was significantly (P < 0.001) higher (76%) among cases than among the matched (38%) and geographic (38%) control populations. Immunoglobulin M to HEV was detected by enzyme-linked immunosorbent assay and Western blot in 16% of sera collected from patients one month after the outbreak. Hepatitis E virus RNA was detected with the polymerase chain reaction in 6% of sera from patients; RNA was not detected in either control group. These results indicate that HEV was the etiologic agent responsible for the outbreak. Children were under-represented among clinical cases. River water served as the principal source for drinking and bathing among most (96%) of the case and control study populations. Boiling of drinking water was negatively associated (P < 0.05) with IgG anti-HEV seropositivity. Unusually heavy rainfall likely contributed to conditions that favored the outbreak. This is the first recognized outbreak of epidemic HEV transmission in Indo-China.

Adolescent↗

PubMed1996

The epidemiology of dengue virus infection among urban, jungle, and rural populations in the Amazon region of Peru.

The first confirmed outbreak of dengue fever in Peru occurred during 1990 in Iquitos, a city of approximately 300,000 residents in the Amazon region. Because of the apparent establishment of endemic transmission of this mosquito-borne viral disease following the outbreak, epidemiologic studies were initiated in 1992. Blood specimens and data on demographic, environmental, and medical history factors were collected from volunteers in an urban sector of Iquitos, in a rural area on the outskirts of Iquitos, and in three nearby jungle communities. A follow-up blood specimen was obtained approximately one year later from a sample of subjects. Sera were tested for dengue IgG antibody by an enzyme-linked immunosorbent assay, and specificity was verified using a plaque-reduction neutralization test. Dengue antibody prevalence was 66% in the urban population, 26% in the rural population, and 32-67% in the three jungle areas. A significant association was found between age and antibody prevalence, with a steady increase in prevalence from 18% among subjects less than five years of age to greater than 90% for subjects more than 50 years old. Increased antibody prevalence also was associated with urban and jungle residence and with a piped source of household drinking water. Seroconversions were documented in four of five surveyed communities. These results indicate that dengue virus transmission continues in and around Iquitos and suggest that transmission also occurred prior to the 1990 epidemic.

Adolescent↗

PubMed1996

The epidemiology of HIV-1 infection in Peru, 1986-1990.

OBJECTIVE: To determine the extent of the HIV-1 epidemic in Peru. DESIGN: Part of a national serosurvey in Peru. METHODS: Between January 1986 and December 1990, 140,976 serum samples were tested for HIV-1 antibody. RESULTS: HIV-1 antibody was found in a high percentage of serum samples provided by 4300 homosexual men (26%), 2204 male sexually transmitted disease patients (10%), 145 drug users (13%), 269 hemophiliacs (10%), and 146 unlicensed female prostitutes (10%). In addition, the prevalence of HIV-1 infection increased substantially among these groups between the beginning and end of the survey period. A low but rising prevalence of HIV-1 antibody was found during this period among serum samples provided by 83,526 blood donors and 11,101 military personnel:total period prevalence, 0.25 and 0.32%, respectively. CONCLUSION: These data indicate that HIV-1 infection is epidemic in Peru among groups at high risk of sexually and parenterally transmitted diseases, and that the risk of infection appears to be low but possibly increasing among the general population.

Disease Outbreaks↗

PubMed1996

A non-invasive assessment of hepatitis B virus carrier status using saliva samples.

A non-invasive testing method to determine hepatitis B virus (HBV) carrier status in pregnant women was evaluated. Paired serum and saliva samples were collected and assessment of hepatitis B markers were performed. Of the 502 women enrolled, 5.6% (28/502) of their sera were found to be positive for HBV surface antigen (HBsAg). Assessment of 28 HBsAg seroreactive and 200 HBsAg sero-non-reactive paired saliva samples showed that 17 saliva contained HBsAg. Fourteen of the saliva reactive samples were matched to the serum reactive samples (50% sensitivity); and 3 saliva samples were positive for HBsAg among 200 subjects seronegative for HBsAg (98.5% specificity). Seven of the 28 HBsAg positive sera were found to be reactive for HBV envelope antigen (HBeAg) (25%). One of seven HBeAg seroreactive and 16 HBeAg seronegative paired saliva samples tested were non-reactive for HBeAg. This report found a non-invasive saliva testing method to be a possible alternative approach for determining chronic HBV carrier status if the sensitivity of the test can be improved.

Carrier State↗

PubMed1995

Epidemiology of Norwalk virus during an outbreak of acute gastroenteritis aboard a US aircraft carrier.

A large outbreak of acute gastroenteritis occurred over a 5-week period aboard an aircraft carrier. The estimated cumulative attack rate was 13% among the 4,500-man crew. Eight percent of the crew sought medical attention, nearly all of whom missed 1 day or more of work. The risk of developing illness was 2 to 3 times greater for individuals living in more crowded sleeping quarters (> 50 persons per compartment). Occurrence of gastroenteritis was associated with a fourfold or more rise in Norwalk virus antibody levels, as measured by an enzyme-linked immunoassay utilizing a baculovirus expressed recombinant antigen. In addition, 27 nm Norwalk virus-like particles were visualized in two of six stools examined by immune electron microscopy. The presence of a low (< 1:50) or a high (> or = 1:6,400) pre-illness antibody level was associated with a lower incidence of illness. This investigation indicates that Norwalk virus can adversely impact operations of a military vessel and that crowding is a major risk factor in transmission.

Acute Disease↗

PubMed1995

Risks of chronicity following acute hepatitis B virus infection: a review.

A bibliographic search was conducted of English-language articles dealing with chronic hepatitis B virus (HBV) infection to evaluate the risk of chronicity following acute infection. Chronic HBV infection was defined as carriage of hepatitis B surface antigen (HBsAg) for at least 6 months. On the basis of incidence studies employing standard serological test methods, the highest risk (80%-90%) of chronic infection was found to be among infected neonates born to hepatitis B e antigen-positive carrier mothers. Of children infected before 6 years of age, chronic infection was reported to develop in approximately 30%. A relatively wide range of risks (< 1%-12%) was found among diverse populations of older children and adults. However, most of the 10 identified incidence studies of generally healthy adults indicated that the risk of chronicity is very low: < or = 5% in eight studies. In addition, the pooled incidence of chronicity was < 5% among two different adult population groups: initially uninfected subjects, who usually experienced asymptomatic infection, and patients presenting with acute hepatitis B. In addition to the primary influence of age, the studies revealed a higher risk of chronic HBV infection among males and among patients with impaired immunity due to various causes.

Acute Disease↗

PubMed1995

The impact of infectious diseases on the health of U.S. troops deployed to the Persian Gulf during operations Desert Shield and Desert Storm.

An assessment was conducted of the impact of infectious diseases on the 697,000 U.S. troops deployed to the Persian Gulf during 1990-1991 in Operations Desert Shield and Desert Storm. The incidence of nonbattle injuries, including infectious diseases, during this conflict was lower than during previous wars involving U.S. military personnel. The major reported causes of morbidity were generally mild cases of acute diarrheal and upper respiratory disease. The most unexpected outcome was the lack of arboviral infections, particularly sandfly fever, and the occurrence among U.S. troops of 12 cases of visceral leishmaniasis due to Leishmania tropica. The fact that infectious diseases were not a major cause of lost manpower, in sharp contrast to the experience among military personnel in World War II, can be attributed to a combination of factors: the presence of a comprehensive infrastructure of medical care, extensive preventive medicine efforts, and several fortuitous circumstances. Beneficial conditions that may not be present in future conflicts in this region include isolation of most combat troops to barren desert locations during the cooler, winter months, which provided the least favorable conditions for transmission of arthropod-borne diseases.

Animals↗

PubMed1995

The risk of human T cell leukemia virus and viral hepatitis infection among US Marines stationed in Okinawa, Japan.

The prevalence and incidence of human T cell leukemia virus type I/II (HTLV-I/II) and hepatitis A, B, and C virus infection were determined among US Marines stationed in Okinawa, Japan. Of 2875 personnel, 2 (0.07%) had antibody to HTLV-I/II. After 1-3 years, no HTLV seroconversions were observed, although 23% reported sexual contact with Okinawans. Of 1010 hepatitis-tested marines, 121 (12%) had antibody to hepatitis A virus (anti-HAV), 26 (2.6%) had antibody to hepatitis B core antigen (anti-HBc), and 2 (0.2%) had antibody to hepatitis C virus (anti-HCV). On follow-up, 1 subject seroconverted to anti-HAV, 8 to anti-HBc, and none to anti-HCV. Most marines with recent hepatitis B infection were young, single, and enlisted and had been on short deployments to other countries in Southeast Asia. Marines stationed in Okinawa are not at high risk for HTLV infection but are at increased risk for hepatitis B infection and should be considered for vaccination.

Adolescent↗

PubMed1995

Serum antibody to lipopolysaccharide antigens of Shigella species among U.S. military personnel deployed to Saudi Arabia and Kuwait during Operations Desert Shield and Desert Storm.

During Operations Desert Shield and Desert Storm, U.S. troops were at high risk of diarrheal disease due to Shigella spp., particularly Shigella sonnei. In order to better understand the serologic response to Shigella infection, 830 male U.S. combat troops were evaluated before and after the deployment to Saudi Arabia and Kuwait for immunoglobulin A (IgA) and IgG anti-Shigella lipopolysaccharide (LPS) (antibody to S. sonnei form I and Shigella flexneri serotypes 1a, 2a, and 3a) in serum. Just before deployment, 10.3% of the subjects were seropositive for IgA and 18.3% were positive for IgG anti-Shigella LPS. IgA and IgG anti-LPS antibody levels in serum prior to deployment were significantly associated with nonwhite race and ethnicity, birth outside the United States, and antibody to hepatitis A virus and Helicobacter pylori. During the deployment, which lasted for a mean of 131 days, 60% of the subjects reported at least one episode of diarrhea and 15% reported an episode of diarrhea with feverishness; also, 5.5% of the subjects exhibited IgA seroconversion to Shigella LPS and 14.0% exhibited IgG seroconversion. A significant association between the development of diarrheal symptoms and either positive predeployment anti-LPS antibody or seroconversion was not found. These data indicate that in this population of U.S. Desert Storm troops who were at high risk of Shigella infection, there was no apparent relation between IgA or IgG anti-Shigella LPS in serum and diarrheal disease.

Adolescent↗

PubMed1995

The risk of Helicobacter pylori infection among U.S. military personnel deployed outside the United States.

To determine whether military personnel deployed outside the United States are at increased risk of Helicobacter pylori infection, 1,000 male U.S. Navy and Marine Corps personnel (mean age 22 years) were evaluated. Study subjects included 200 recruits, 500 shipboard personnel deployed for six months to South America, West Africa, and the Mediterranean, and 300 ground troops deployed for five months to Saudi Arabia. Among all 1,000 subjects, 247 (25%) were seropositive for H. pylori IgG antibody by an enzyme-linked immunosorbent assay; 24% of new recruits and 25% of troops who had been on active duty for a mean of four years. The prevalence of H. pylori antibody was higher among subjects who were older, nonwhite, foreign-born, and seropositive for antibody to hepatitis A virus. Among the 601 initially seronegative subjects evaluated before and after a 5-6 month deployment outside the United States, five seroconverted, for a rate of infection of 1.9% per person-year of exposure. As found in other populations in developed countries, these data indicate that among U.S. military personnel a large proportion of H. pylori infections occur before adulthood and infection is related to demographic factors. These preliminary findings also suggest that deployed U.S. military personnel may be at increased risk of H. pylori infection compared with adult populations in developed countries either from exposure in developing countries or from crowding.

Adolescent↗

PubMed1995

A high risk of hepatitis C infection among Egyptian blood donors: the role of parenteral drug abuse.

To determine the prevalence and risk factors of hepatitis C virus (HCV) infection among Egyptian blood donors, 188 consecutive adult blood donors from four hospitals and one temporary donor center located in Cairo, Egypt were evaluated. Sera were tested for HCV antibodies (anti-HCV) using second-generation enzyme-linked immunosorbent assay (ELISA) test kits. Sera that were repeatedly reactive by ELISA were further verified by a second-generation recombinant immunoblot assay (RIBA). Antibodies to HCV were detected by RIBA in 26.6% of the blood donors, which is higher than the 10-19% prevalence of antibody found in other studies of Egyptian blood donors. A history of selling blood (odds ratio [OR] = 12.1) and the use of illicit parenteral drugs (OR = 2.5) were significantly associated with anti-HCV seropositivity after controlling for age and gender. These data indicate that the use of illicit drugs may be one reason for high levels of reported HCV infection among Egyptian blood donors. These findings also indicate that Egyptian blood donors should be screened for anti-HCV and individuals who have a history of drug abuse should be deferred from donating blood.

Adolescent↗

PubMed1995

The risk of viral hepatitis A, B, C, and E among North American missionaries.

The seroprevalence and incidence of hepatitis A, B, C, and E virus infection were determined among North American missionaries (n = 328) serving in various geographic locations between 1967 and 1984. The mean age of subjects at entry into the study was 39.7 years (range 5-73 years); 65% were female; 89% had lived outside the United States before the study began. Seventy-eight percent of subjects served in sub-Saharan Africa during the study. At initial evaluation, 50.9% of the subjects had antibodies to hepatitis A virus (total anti-HAV), 8.5% to hepatitis B virus core antigen (total anti-HBc), 0.6% to hepatitis C virus (total anti-HCV by second-generation immunoblot assay), and 0% to hepatitis E virus (IgG anti-HEV). After an average period of service of 7.3 years (2,396 person-years total), 5.8% of the missionaries seroconverted to anti-HAV, 5.5% to anti-HBc, 0.6% to anti-HCV, and 0% to anti-HEV. This study indicates a relatively low risk of hepatitis C and E virus infection among missionaries while confirming the previously reported high risk of hepatitis A and B virus infection. Hepatitis A and B vaccination is recommended for long-term travelers to developing countries.

Adolescent↗

PubMed1995

Comparative study of the immunogenicity and safety of two dosing schedules of hepatitis B vaccine in neonates.

Healthy Egyptian neonates born to hepatitis B surface antigen (HBsAg)-seronegative mothers were randomly enrolled in one of three vaccination schedules. A dose of 2.5 micrograms of recombinant HB vaccine was given at birth, two, and six months of age (group A) or two, four, and nine months of age (group B). These two groups and a third control group (group C) also were given the other routine childhood vaccines (BCG, DPT, polio, and measles). Blood samples were taken one month after the third vaccine dose in groups A (seven months of age) and B (10 months of age), and a second follow-up blood sample was taken at the age of 18 months for all three groups. Sera were tested for HBsAg and antibody to hepatitis B core antigen, and quantitatively for antibody to hepatitis B surface antigen (anti-HBs) using commercial enzyme immunoassay kits. The vaccine was well tolerated and side effects were limited to local soreness, redness, or temporary swelling. Among 590 infants who were followed-up, good (51-300 mIU anti-HBs/ml) or excellent (> 300 mIU/ml) immune responses occurred in 85% of the infants in group A and in 96% in group B. Geometric mean titers of anti-HBs at the first and second follow-up were 306 and 55 mIU/ml in group A, and 1,492 and 147 mIU/ml in group B. The recombinant HB vaccine is safe and immunogenic when given in three doses of 2.5 micrograms in either regimen, but delay of the booster dose of the vaccine until nine months after birth produced a higher immune response.

Female↗

PubMed1994

Chronic liver disease in Peru: role of viral hepatitis.

The prevalence of antibodies to hepatitis C virus (anti-HCV) was determined in 105 patients with biopsy-proven chronic liver disease and 128 comparison patients without any evidence of liver pathology living in Lima, Peru. Using a second-generation EIA screening and supplemental immunoblot assay, anti-HCV was detected in four of 13 patients with chronic hepatitis, in 11% of 85 patients with cirrhosis, and in none of seven patients with hepatocellular carcinoma. Only two (1.6%) comparison patients without liver disease had anti-HCV. Hepatitis B surface antigen (HBsAg) was found in 23% of patients with chronic hepatitis, 12% of patients with cirrhosis, and three of seven patients with hepatocellular carcinoma. There was no evidence of chronic viral hepatitis or alcohol abuse (reported by one-third of subjects) in 48% of chronic liver disease patients. These preliminary data suggest that among this South American population neither hepatitis B nor hepatitis C infection is the predominate cause of chronic liver disease and that other infectious or environmental factors may be important.

Adult↗

PubMed1994

Enhanced chemiluminescence as a means of increasing the sensitivity of western blot assays for HIV antibody.

Chemiluminescence indicator systems offer several advantages for diagnostic assays and have been used successfully to increase the sensitivity of antibody and antigen assays. A technique of enhanced chemiluminescence (ECL) was applied as a replacement for routine chromogenic substrates on HIV-1 Western blots. The results indicated that the enhanced chemiluminescence detection system increased the sensitivity by greater than 10-fold over routine chromogenic indicator systems when testing diluted, reactive sera. When testing 9 seroconversion panels, the use of ECL indicated that early detection of HIV infection was elicited in six panels up to 31 days (average 11.4 days) prior to detection by routine FDA-licensed Western blots, and could be detected in all panels up to 43 days (average 18.8 days) prior to detection by in-house Western blots. In no case was the ECL Western blot system less sensitive than any of the chromogenic Western blots, and in several cases the maximum potential of the ECL system for early detection of antibody could not be determined. The ECL system was capable of detecting antibodies to envelope antigens at a 20-fold increase over chromogenic Western blots. The time of detection of seropositivity by the ECL Western blot was equal to that of most ELISAs in 5 panels and was 31 days earlier than ELISA in one panel. Permanent documentation of Western blot profiles was accomplished using a simple instamatic camera system capable of detecting the chemiluminescence signal, and blots could be re-probed using a second sample.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Western↗

PubMed1994

Application of a rapid assay for detection of antibodies to human immunodeficiency virus in urine.

The use of rapid, simple tests to detect antibodies to human immunodeficiency virus (HIV) in urine could be valuable for several testing situations, such as in private offices, for epidemiologic surveys, and in developing countries. The authors evaluated the performance of the SUDS HIV type 1 test to detect antibody to HIV-1 peptides in urine. Test performance and applicability of the SUDS test were compared with a routine Food and Drug Administration-licensed enzyme-linked immunosorbent assay (ELISA) and Western blot using 139 serum and urine pairs collected from autopsy cases. Using a modified procedure when testing urine by the SUDS test, results indicated that a total of 15 serum/urine pairs were HIV-1 antibody positive by both the SUDS test and ELISA; all could be confirmed positive by Western blot. One sample produced discrepant results. The SUDS test produced no false-positive results when testing serum or urine, as compared with ELISA, and no false-negative results when compared with the Western blot. For optimal accuracy of detection of antibodies using urine, at least 100 microL of sample was required. By Western blot analysis, antibody profiles in urine were generally weaker than in serum, but confirmation of positivity was not compromised when larger volumes were used. The authors concluded that this rapid HIV-1 test, when used to detect antibodies to HIV-1 in urine, is accurate, easy to perform, and appropriate for use in certain testing situations.

Blotting, Western↗

PubMed1994

Threat of hepatitis E virus infection in Somalia during Operation Restore Hope.

In support of Operation Restore Hope, the United States military established a diagnostic laboratory for infectious diseases, the Joint Forward Laboratory, in Mogadishu, Somalia. Because sporadic hepatitis due to unknown causes was a frequent problem, staff members of the Joint Forward Laboratory evaluated 31 Somalis, five displaced Ethiopians, and three Western relief workers who had acute clinical hepatitis. Patients lived in multiple locations in Somalia--Mogadishu, Baidoa, and Merca--and became ill between December 1992 and February 1993. IgM antibody to hepatitis A virus was found in one English relief worker, and IgM antibody to hepatitis E virus was found in 20 (65%) of 31 Somalis, two (40%) of five Ethiopians, and two (67%) of three Western relief workers. No patient had evidence of acute hepatitis B, malaria, yellow fever, or other arbovirus infections. These data indicate that hepatitis E virus--the major cause of enterically transmitted non-A, non-B hepatitis--was a common cause of acute sporadic hepatitis in Somalia during the initial stages of Operation Restore Hope.

Disease Outbreaks↗

PubMed1994

Short-course norfloxacin and trimethoprim-sulfamethoxazole treatment of shigellosis and salmonellosis in Egypt.

In a double-blind clinical study, 109 adult Egyptian patients infected with Shigella spp. and 45 infected with Salmonella spp. were randomly assigned to three treatment groups: 1) norfloxacin in a single 800-mg dose, 2) norfloxacin, 400 mg twice a day for three days, and 3) trimethoprim (160 mg)-sulfamethoxazole (800 mg) (TMP-SMX), twice a day for three days. Among Shigella-infected patients, diarrheal symptoms had resolved in 86-97% and bacteriologic failure (repeat positive stool culture) occurred in only two patients five days after the start of the three treatment regimens. Among Salmonella-infected patients, diarrheal symptoms had resolved in 76-82% of patients and bacteriologic failure was common (18-36%) five days after the start of therapy. These data indicate that short-course therapy with either norfloxacin or TMP-SMX can be effectively used to treat shigellosis in adults in developing countries. However, for uncomplicated Salmonella spp. infection, short-course therapy with norfloxacin and TMP-SMX may not lead to a rapid resolution of symptoms or consistently eliminate this enteropathogen.

Adult↗