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D M Watts

Publications and source records attributed to D M Watts.

At least 37 records · Page 2Linked to original sources
PubMed1999

Isolation and genetic characterization of a hantavirus (Bunyaviridae: Hantavirus) from a rodent, Oligoryzomys microtis (Muridae), collected in northeastern Peru.

This paper describes the isolation and partial genetic characterization of a hantavirus from a pygmy rice rat, Oligoryzomys microtis, collected within the urban area of Iquitos, Loreto Department, Peru. The virus, designated HTN-007, exhibited the highest degree of genetic similarity to Rio Mamore virus, which was originally described from the same rodent species in eastern Bolivia. Comparison of small and medium segment nucleotide sequence data from HTN-007 and Rio Mamore virus revealed 87% and 85% sequence identity, respectively. Based on these analyses, HTN-007 appears to be a variant of Rio Mamore virus. As such, it represents the first successful isolation of Rio Mamore virus and the first evidence for the existence of a hantavirus in Peru. Serologic studies done by immunofluorescence on blood samples of 56 O. microtis trapped at the collection site indicated that 21.4% had antibodies to hantavirus. In view of the proximity of this rodent species to humans and the close phylogenetic relationship of Rio Mamore virus to hantaviruses that have been associated with human disease, Rio Mamore virus may be a hantavirus of some public health importance in tropical South America.

Animals↗
PubMed1998

Resectional gastric bypass is a new alternative in morbid obesity.

BACKGROUND: Severe obesity is a common serious health problem in the United States. Medical therapy is often ineffective. A variety of surgical procedures have been employed for treatment of morbid obesity. Surgical therapy continues to evolve. METHODS: Eighty-five patients have undergone subtotal gastrectomy and retrocolic Roux-en-Y gastrojejunostomy for weight control at our institution. We refer to this procedure as resectional gastric bypass (RGB). Thirty-eight patients have undergone RGB as conversion from failed or problematic prior bariatric procedures. Forty-seven patients have had RGB as their primary bariatric procedure. RESULTS: Twenty-six patients undergoing RGB for conversion of an anatomically or functionally failed prior bariatric procedure have had mean additional weight loss of 37% excess body weight (EBWL) in 18 months follow-up. Twelve patients undergoing RGB for intractable side effects of prior bariatric procedures have all had clinical improvement. Forty-seven patients undergoing RGB as a primary procedure have had EBWL of 53%, in mean follow-up of 11 months. For the entire series, major complications were one anastomotic leak, one reexploration for suspected subphrenic abscess, and one major pulmonary embolus. These patients recovered. There was no mortality in the series. CONCLUSIONS: Resectional gastric bypass is a new alternative for salvage of a failed or problematic prior bariatric procedure. It is also effective as a primary weight control operation.

Adult↗
PubMed1998

Evaluation of recombinant dengue viral envelope B domain protein antigens for the detection of dengue complex-specific antibodies.

To increase the specificity of dengue (DEN) diagnosis based on antibody detection, we have evaluated recombinant proteins as antigens that incorporate most of the B domain of the DEN virus envelope protein fused to the trpE protein of Escherichia coli (trpE-DEN). A pooled antigen consisting of trpE-DEN proteins representing all four serotypes of DEN virus was used in an indirect ELISA for the detection of IgG or IgM antibody. This assay was compared with a standard IgG indirect ELISA and an IgM-capture ELISA using DEN virus-infected cell culture pooled antigens. The results indicated that the trpE-DEN antigens and the cell culture antigens were equally sensitive for detecting IgM and IgG antibodies in convalescent sera from Peru and Indonesia representing virus isolation-confirmed primary and secondary DEN infections, respectively. Fourteen day postinfection IgG antibody-positive sera obtained from individuals infected with DEN-1 virus who had been vaccinated with other flaviviruses were more strongly reactive with the cell culture antigen than with the recombinant antigen, but by day 21 postinfection, a strong antibody response to the trpE-DEN antigens was present. These results suggested that the early antibody response was directed predominantly towards shared flavivirus group antigens that were not detected with the trpE-DEN antigens. Comparison of the trpE-DEN-1 recombinant antigen with a DEN-1 virus-infected cell lysate antigen for the detection of IgG antibody in sera from a cohort of 55 individuals from Peru who seroconverted over a one-year period indicated greater specificity for the recombinant antigens. Also, sera from individuals with no known DEN infections that had been sequentially vaccinated with yellow fever and Japanese encephalitis reacted with the DEN virus cell culture antigen in the IgG ELISA, but did not react with the trpE-DEN pooled antigens. Similarly, YF IgM antibody positive samples that showed cross-reactivity with the DEN virus cell culture antigens, did not react with the trpE-DEN pooled antigens. These results indicated that the trpE-DEN pooled antigen provided a more specific diagnosis of dengue infections than DEN virus-infected cell culture antigen and avoided the biohazards associated with handling live virus during the preparation of diagnostic reagents. The trpE-DEN pooled antigen should permit a better approach to distinguish between past DEN and other flavivirus infections in epidemiologic surveys, and also increase the specificity of serologic diagnosis of acute DEN infections.

Antibodies, Viral↗
PubMed1998

Venezuelan equine encephalitis febrile cases among humans in the Peruvian Amazon River region.

A survey was conducted from October 1, 1993 to June 30, 1995 to determine the arboviral etiologies of febrile illnesses in the city of Iquitos in the Amazon River Basin of Peru. The study subjects were patients who were enrolled at medical care clinics or in their homes by Peruvian Ministry of Health (MOH) workers as part of the passive and active disease surveillance program of the MOH. The clinical criterion for enrollment was the diagnosis of a suspected viral-associated, acute, undifferentiated febrile illness of < or = 5 days duration. A total of 598 patients were enrolled in the study. Demographic information, medical history, clinical data, and blood samples were obtained from each patient. The more common clinical features were fever, headache, myalgia, arthralgia, retro-ocular pain, and chills. Sera were tested for virus by the newborn mouse and cell culture assays. Viral isolates were identified initially by immunofluorescence using polyclonal antibody. An ELISA using viral-specific monoclonal antibodies and nucleotide sequence analysis were used to determine the specific variety of the viruses. In addition, thin and thick blood smears were observed for malaria parasites. Venezuelan equine encephalitis (VEE) virus subtype I, variety ID virus was isolated from 10 cases, including three cases in October, November, and December 1993, five cases in January and February 1994, and two cases in June 1995. The ELISA for IgM and IgG antibody indicated that VEE virus was the cause of an additional four confirmed and four presumptive cases, including five from January through March 1994 and three in August 1994. Sixteen cases were positive for malaria. The 18 cases of VEE occurred among military recruits (n = 7), agriculture workers (n = 3), students (n = 3), and general laborers (n = 5). These data indicated that an enzootic strain of VEE virus was the cause of at least 3% (18 of 598) of the cases of febrile illnesses studied in the city of Iquitos in the Amazon Basin region of Peru.

Adolescent↗
PubMed1998

Identification and genetic analysis of Panama-genotype Venezuelan equine encephalitis virus subtype ID in Peru.

Venezuelan equine encephalitis (VEE) virus was isolated in 1993, 1994, and 1995 from human cases of acute, undifferentiated, febrile illness in the Peruvian Amazon Basin. Two virus isolates were recovered in 1994 from Peruvian soldiers at a jungle outpost near Pantoja in northern Peru, and 10 isolates were obtained from military personnel and civilians in 1993-1995 in Iquitos, an urban center in northeastern Peru. The genetic relationship of these isolates to other VEE virus strains was determined by sequencing 856-867 nucleotide reverse transcription-polymerase chain reaction fragments derived from the PE2 glycoprotein gene. The sequences were compared with those of other VEE virus strains, including representatives of the IAB, IC, ID, IE, II, and IIIC subtypes. The two Pantoja isolates were most closely related to subtype IC and ID viruses previously isolated in Colombia and Venezuela, and to the ID viruses isolated during the 1970s in Iquitos. All of the recent Iquitos isolates were similar to one another, but they were more closely related to Panamanian ID strains than to isolates previously obtained in Iquitos, Peru, or in Colombia and Venezuela. The recent Iquitos VEE viral isolates were the first Panama-genotype VEE ID virus strains identified outside of the Republic of Panama.

Animals↗
PubMed1998

Geographic distribution and clinical description of leishmaniasis cases in Peru.

Studies were conducted from 1986 through 1993 to further define the geographic distribution and relative importance of different species of Leishmania as a cause of leishmaniasis in Peru. Patients with a clinical diagnosis of cutaneous and/or mucosal or diffuse cutaneous leishmaniasis were enrolled at the Naval Medical Research Institute Detachment (NAMRID) Laboratory in Lima, the Tropical Disease Clinic at San Marcos University Daniel A. Carrión, the Central Military Hospital, and a Ministry of Health hospital in Cusco, Peru. Clinical features, lesion aspirates, and biopsy tissue were obtained from each patient. All specimens were collected and assayed separately, including multiple specimens from some of the same patients for Leishmania parasites by inoculating aliquots of either aspirates or biopsy tissue suspensions onto Senekji's blood agar medium. Stocks of Leishmania isolates were used to prepare promastigotes to produce extracts for identifying the Leishmania species by the cellulose acetate electrophoresis enzyme technique. A total of 351 isolates of Leishmania were obtained from 350 patients who were infected primarily in the low and high jungle of at least 15 different Departments of Peru. Of the 351 isolates, 79% were identified as L. (V.) braziliensis, 7% as L. (V.) guyanensis, 10% as L. (V.) peruviana, 2% as L. (V.) lainsoni, and 1.7% as L. (L.) amazonensis. The clinical form of disease varied depending on the species of Leishmania, with L. (V.) braziliensis being associated most frequently with cutaneous, mucosal ulcers and mixed cutaneous and mucosal disease, and L. (V) peruviana, L. (V.) guyanensis, L. (V.) lainsoni with cutaneous lesions. Leishmania (L.) amazonensis was isolated from six patients, three with cutaneous lesions, one with mucosal lesions, and two with diffuse cutaneous lesions. Among all of the leishmaniasis cases, males were affected more frequently, and cases occurred among patients less than 10 to more than 51 years of age. These data further defined the geographic distribution and the relative frequency of Leishmania species associated with different clinical forms of leishmaniasis in Peru.

Adolescent↗
PubMed1998

Epidemiology of endemic Oropouche virus transmission in upper Amazonian Peru.

A cross-sectional serosurvey of a rural community near Iquitos, Peru was conducted to determine Oropouche (ORO) virus antibody prevalence and risk factors for human infection. Venous blood samples, and demographic, social, and risk factor data were obtained from people age five years of age and older who lived in the village of Santa Clara on the Nanay River, a tributary of the Amazon River. Sera were tested for ORO viral antibody by an ELISA. The specificity of viral antibody reactivity was determined by a standard plaque-reduction neutralization test. Interview data were analyzed by univariate and multiple logistic regression to determine which variables were statistically associated with previous ORO viral infection, as indicated by the presence of IgG antibody. Final models were evaluated based on log-likelihood and Wald chi-square. Clustering of seropositive residents within houses was analyzed by the method of Walter. Among 1,227 persons sampled, 33.7% (n=414) were positive for ORO viral IgG antibody. Overall, antibody prevalence was similar for males (33.9%) and females (33.6%), and increased significantly with age for both sexes to include more than half of persons more than 25 years of age. The length of residence in the village was positively associated with serologic status; persons who had moved to the village within the past 15 years were less likely to be seropositive than life-long residents of the same age. Antibody prevalence among immigrants who had lived in Santa Clara more than 15 years was similar to that in life-long residents. The activity most predictive of previous ORO viral infection was travel to forest communities and travel to Iquitos. No evidence of spatial heterogeneity in ORO virus antibody distribution was observed. Results suggested that endemic transmission of ORO virus in this region has been ongoing during many decades, and that people are at considerable risk of infection.

Adolescent↗
PubMed1997

Evaluation of a dipstick enzyme-linked immunosorbent assay for detection of antibodies to dengue virus.

Accurate serological confirmation of dengue (DEN) infection is difficult, because simple reliable assays for the detection of DEN antibodies are not available. To address this problem, a dipstick enzyme-linked immunosorbent assay (ELISA) was evaluated. The dipstick contained dots of serially diluted DEN 2 antigen. To detect immunoglobulin G (IgG), the dipstick was processed through four reaction cuvettes containing test serum, enhancer, enzyme-conjugated anti-human IgG and IgM antibody, and substrate. Total assay time was 45 min. To detect IgM, the serum was passed through a protein G device to remove IgG. The dipstick was then processed as before, except that the incubation times were longer and enzyme-conjugated anti-human IgM was used. The total assay time was 3 h. The dipstick ELISA results were compared with results from microplate ELISA. The IgG dipstick ELISA showed a sensitivity of 95.2% and a specificity of 100% compared to an IgG microplate ELISA with serum samples from 125 individuals living in an area in which DEN is endemic. In tests with 75 serum samples from patients with clinically suspected acute DEN infections, the IgM dipstick ELISA showed a sensitivity of 97.9% and specificity of 100% compared to those of an IgM antibody capture microplate ELISA. These results showed that the dipstick ELISA was a sensitive and specific test for the detection of either DEN IgM or IgG in human serum. The dipstick ELISA was also shown to be useful for detecting seroconversions to DEN IgM or IgG in paired serum samples from 20 patients with virus isolation-confirmed acute DEN infections.

Animals↗
PubMed1997

Oropouche virus transmission in the Amazon River basin of Peru.

Seroepidemiologic studies were conducted to determine the prevalence of Oropouche (ORO) viral antibody, risk factors, and the incidence of infection among residents of the Amazon region of Peru. Blood samples, as well as demographic, cultural, and medical history data, were collected from residents in a sector of the city of Iquitos and in an adjacent rural and three neotropical rain forest communities. Blood specimens were obtained approximately one year later from a cohort of the same study subjects who were negative for ORO antibody on the initial cross-sectional survey. Sera were tested for ORO IgG antibody by an enzyme-linked immunosorbent assay. Antibody prevalences were 35% for residents of the urban population, 24-46% for the forest communities, and 18% for the rural community. Antibody prevalence increased with age, and subjects who were seropositive were significantly (P = 0.001) older (mean = 33 years) than the seronegative subjects (mean = 15 years). Multivariate analysis revealed that only age, urban and forest residence, and occupation as a farmer or housekeeper remained significantly associated with seropositivity. Seroconversion data for the same populations one year later demonstrated evidence of ORO viral infection among 28% of the residents in the rural community and 2% or less in the forest and urban communities. Oropouche virus infection was significantly associated with older age (P = 0.04) in the rural community (P < 0.001). These data support prior evidence of ORO viral infection among residents of Iquitos and surrounding villages and suggest that transmission of this virus occurs continuously in the population of this area of the Amazon basin.

Adolescent↗
PubMed1997

Venezuelan equine encephalitis and Oropouche virus infections among Peruvian army troops in the Amazon region of Peru.

An outbreak of a febrile illness characterized by headache, ocular pain, myalgia, and arthralgia occurred during June 1994 among Peruvian army troops in Northern Peru. On June 14-16, 1994, clinical data and blood samples were obtained from eight soldiers with a febrile illness, and from 26 others who had a history of febrile illness during the past three months. A follow-up blood sample was obtained 107 days later from four of the febrile and seven of the afebrile soldiers. Serum samples were tested for dengue (DEN), Oropouche (ORO), and Venezuelan equine encephalitis (VEE) IgM and IgG antibodies by an enzyme-linked immunosorbent assay (ELISA). Virus isolation was performed by inoculation of newborn mice and Vero cell cultures. Viral isolates were identified by immunofluorescence, ELISA, and nucleotide sequencing. A VEE virus infection was confirmed in three of the eight febrile soldiers, two by virus isolation, and one by serology. Antigenic analysis indicated that one of the virus isolates was similar to VEE subtype I, variety ID, viruses previously isolated in Colombia and Venezuela. Nucleotide sequence data showed that both viral isolates were identical to one another and closely related to VEE ID viruses previously isolated in Peru, Colombia, and Venezuela. Serologic results showed that two of 26 afebrile soldiers had IgM antibody to VEE and four had IgG antibody to VEE; two febrile soldiers had IgG antibody in their first serum samples. Oropouche-specific IgM antibody was detected in one of the eight febrile and five of the afebrile soldiers, and 18 of the 34 soldiers had low titers of ORO IgG antibody titers, which did not meet the diagnostic criteria for confirmed cases. All soldiers were negative for DEN IgM antibody, and 10 had flavivirus IgG antibody that reacted with DEN antigens. These data indicated that VEE ID virus was one of the causes of illness among Peruvians soldiers and that this was the first association of this VEE subtype with human disease in Peru.

Adolescent↗
PubMed1997

Application of an immunoperoxidase monolayer assay for the detection of arboviral antibodies.

An immunoperoxidase monolayer assay (IPMA) was adapted for the detection of antibodies to six arboviruses: three viruses within the flavivirus group (dengue 2, West Nile (WN) and yellow fever) and three in the phlebovirus group (Rift Valley fever (RVF), sandfly fever Naples and sandfly fever Sicilian). Antibody titers of homologous hyper-immune mouse ascitic fluid (HMAF) measured by IPMA were two to eight-fold less than those determined by ELISA. In tests with heterologous HMAF, cross-reactions frequently observed in ELISA, particularly in the flavivirus group, were absent in all IPMA titrations. With human serum samples tested for antibodies to RVF (n = 52) and WN (n = 90), the sensitivity of IPMA as compared with ELISA was 96 and 91%, respectively, specificity of IPMA was 100%. In addition, the IPMA format has several advantages that make it a useful alternative to ELISA for diagnosing arboviral infections under field conditions.

Antibodies, Viral↗
PubMed1996

Genetic variation in yellow fever virus: duplication in the 3' noncoding region of strains from Africa.

The nucleotide sequences of three regions of the genomes of 13 yellow fever (YF) virus isolates were determined to define genetic variation and evolution of the virus. Phylogenetic trees generated from sequences of either the 5' terminal 1320 nucleotides of the genome, 754 nucleotides from the NS4A and NS4B genes, or the 3' terminal 511 nucleotides were very similar and contained minor differences. Overall, these results suggested that there were at least four major genotypes of YF virus, including one in Central/East Africa, one in West Africa, and two in South America. Examination of the 3' noncoding region (3'NCR) showed that only West African strains had a 3'NCR of 511 nucleotides while strains from Central/East Africa and South America had shorter 3'NCRs (443-469 nucleotides) due to the absence of YF specific repeat sequences (RYFs). Central/East African strains have two RYFs and West African strains have three RYFs while South American strains only have one copy of the RYF. It is speculated that duplication of the RYF took place in West Africa subsequent to the presumed introduction of YF virus into South America. Thus, both tick-borne (Mandl et al., J. Virol. 65, 4070-4077, 1991 and Wallner et al., Virology 213, 169-178, 1995) and mosquito-borne flaviviruses have variable 3'NCRs.

Africa↗
PubMed1996

Evaluation of arthropod-borne viruses and other infectious disease pathogens as the causes of febrile illnesses in the Khartoum Province of Sudan.

The relative importance of arthropod-borne and other disease pathogens as the cause of an outbreak of febrile illnesses was assessed during August 1988, following severe flooding in Khartoum, Sudan. A total of 200 patients with acute febrile illness and 100 afebrile controls were enrolled in the study during October and November 1988; at the Omdurman Military Hospital, Khartoum, Sudan. Sera were tested for IgM and IgG antibodies to six arthropod-borne viruses by an enzyme-linked immunoabsorbent assay, and for similar antibodies to Lassa fever, Crimean-Congo hemorrhagic fever, and Ebola and Marburg viruses by an indirect fluorescence assay. Thick and thin blood smears were examined microscopically for malaria parasites, and fecal and blood specimens were tested for bacteria by standard culture methods. Among the acute and convalescent sera collected from 67 febrile patients, five cases were caused by sandfly fever Sicilian (SFS), six by sandfly fever Naples (SFN), and 12 by unidentified phleboviruses. Of 233 remaining unpaired, acute-phase sera collected from cases and controls, 49 (21%) had IgM antibodies to SFS or SFN, RVF, West Nile (WN), and Chikungunya (CHIK) viruses. Forty-three (22%) of 192 febrile cases and two of the 100 afebrile controls were positive for Plasmodium falciparum, and bacterial enteropathogens were associated with 25 (13%) cases and four controls. These data indicated that phleboviruses and to a lesser extent, WN, P. falciparum, and enterobacterial pathogens were causes of acute febrile illnesses following the 1988 flood in Khartoum, Sudan.

Acute Disease↗
PubMed1996

Hepatitis B virus (HBV)/hepatitis D virus (HDV) coinfection in outbreaks of acute hepatitis in the Peruvian Amazon basin: the roles of HDV genotype III and HBV genotype F.

Recurring outbreaks of acute hepatitis have been a significant cause of morbidity and mortality among Peruvian military personnel stationed in the Amazon Basin region of Peru. The role of hepatitis B virus (HBV) and hepatitis D virus (HDV) infection was investigated as the possible cause of acute hepatitis among 88 military patients stationed at four different jungle outposts during 1992-1993. Analysis of serum markers indicated that 95% (84/88) had evidence of acute HBV infection; 64% (54/84) were also infected with HDV. Genetic analysis of PCR-amplified HDV and HBV fragments showed exclusively HDV genotype III and HBV genotype F. Furthermore, HDV RNA sequences were similar among patients from the same outpost but different from those at other jungle locations. The data suggested focal sources of HDV infection in the jungle environment of the outposts and, further, confirmed the unique association of HDV genotype III with severe cases of human disease in northern South America.

Acute Disease↗
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↗