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Ali S Khan

Publications and source records attributed to Ali S Khan.

18 recordsLinked to original sources
PubMed2005

Evaluation of human-to-human transmission of monkeypox from infected patients to health care workers.

BACKGROUND: In 2003, human monkeypox was first identified in the United States. The outbreak was associated with exposure to infected prairie dogs, but the potential for person-to-person transmission was a concern. This study examines health care worker (HCW) exposure to 3 patients with confirmed monkeypox. METHODS: Exposed HCWs, defined as HCWs who entered a 2-m radius surrounding case patients with confirmed monkeypox, were identified by infection-control practitioners. A self-administered questionnaire and analysis of paired serum specimens determined exposure status, immune response, and postexposure signs and symptoms of monkeypox. RESULTS: Of 81 exposed HCWs, 57 (70%) participated in the study. Among 57 participants, 40 (70%) had > or =1 unprotected exposure; none reported signs or symptoms consistent with monkeypox illness. One exposed HCW (2%), who had been vaccinated for smallpox within the past year, had serological evidence of recent orthopoxvirus infection; acute- and convalescent-phase serum specimens tested positive for anti-orthopoxvirus IgM. No exposed HCWs had signs and symptoms consistent with monkeypox. CONCLUSION: More than three-quarters of exposed HCWs reported at least 1 unprotected encounter with a patient who had monkeypox. One asymptomatic HCW showed laboratory evidence of recent orthopoxvirus infection, which was possibly attributable to either recent infection or smallpox vaccination. Transmission of monkeypox likely is a rare event in the health care setting.

Adult↗
PubMed2005

Transmission of monkeypox among persons exposed to infected prairie dogs in Indiana in 2003.

OBJECTIVE: To describe a cluster of human monkeypox cases associated with exposure to ill prairie dogs in a home child care. DESIGN, SETTING, PARTICIPANTS: We identified all persons exposed to 2 pet prairie dogs in County A, Indiana; performed active surveillance for symptomatic monkeypox infection; and evaluated the types of exposure that may have resulted in infection. For children who attended the child care where the animals were housed, we also measured the rate of seroconversion to monkeypox virus. MAIN OUTCOME MEASURES: Nine (13%) of 70 persons exposed to the prairie dogs reported signs and symptoms of monkeypox. Two (40%) of 5 symptomatic child care attendees reported direct contact with the prairie dogs. Two (13%) of 15 child care attendees evaluated tested positive for IgM antibodies against orthopoxvirus; both reported symptoms consistent with monkeypox. RESULTS: The risk of symptomatic infection correlated with the time and intensity of animal exposure, which was 100% (4/4) among family members with extensive direct contact, 19% (5/26) among the veterinarian and nonfamily child care attendees with moderate exposure, and 0% (0/40) among school children with limited exposure (P<.01). CONCLUSIONS: Monkeypox virus was transmitted from ill prairie dogs in a child care and veterinary facilities. The risk of symptomatic infection correlated with the amount of exposure to the prairie dogs. Although most cases of human monkeypox were associated with direct animal contact, other routes of transmission cannot be excluded.

Adult↗
PubMed2004

SARS surveillance during emergency public health response, United States, March-July 2003.

In response to the emergence of severe acute respiratory syndrome (SARS), the United States established national surveillance using a sensitive case definition incorporating clinical, epidemiologic, and laboratory criteria. Of 1,460 unexplained respiratory illnesses reported by state and local health departments to the Centers for Disease Control and Prevention from March 17 to July 30, 2003, a total of 398 (27%) met clinical and epidemiologic SARS case criteria. Of these, 72 (18%) were probable cases with radiographic evidence of pneumonia. Eight (2%) were laboratory-confirmed SARS-coronavirus (SARS-CoV) infections, 206 (52%) were SARS-CoV negative, and 184 (46%) had undetermined SARS-CoV status because of missing convalescent-phase serum specimens. Thirty-one percent (124/398) of case-patients were hospitalized; none died. Travel was the most common epidemiologic link (329/398, 83%), and mainland China was the affected area most commonly visited. One case of possible household transmission was reported, and no laboratory-confirmed infections occurred among healthcare workers. Successes and limitations of this emergency surveillance can guide preparations for future outbreaks of SARS or respiratory diseases of unknown etiology.

Adolescent↗
PubMed2004

SARS transmission and hospital containment.

An outbreak of severe acute respiratory syndrome (SARS) was detected in Singapore at the beginning of March 2003. The outbreak, initiated by a traveler to Hong Kong in late February 2003, led to sequential spread of SARS to three major acute care hospitals in Singapore. The critical factor in containing this outbreak was early detection and complete assessment of movements and follow-up of patients, healthcare workers, and visitors who were contacts. Visitor records were important in helping identify exposed persons who could carry the infection into the community. In the three hospital outbreaks, three different containment strategies were used to contain spread of infection: closing an entire hospital, removing all potentially infected persons to a dedicated SARS hospital, and managing exposed persons in place. On the basis of this experience, if a nosocomial outbreak is detected late, a hospital may need to be closed in order to contain spread of the disease. Outbreaks detected early can be managed by either removing all exposed persons to a designated location or isolating and managing them in place.

Adult↗
PubMed2004

Outbreak of hantavirus pulmonary syndrome, Los Santos, Panama, 1999-2000.

An outbreak of hantavirus pulmonary syndrome occurred in the province of Los Santos, Panama, in late 1999 and early 2000. Eleven cases were identified; 9 were confirmed by serology. Three cases were fatal; however, no confirmed case-patient died. Case-neighborhood serologic surveys resulted in an overall hantavirus antibody prevalence of 13% among household and neighborhood members from the outbreak foci. Epidemiologic investigations did not suggest person-to-person transmission of hantavirus infection. By use of Sin Nombre virus antigen, hantavirus antibodies were detected in Oligoryzomys fulvescens and Zygodontomys brevicauda cherriei. This outbreak resulted in the first documented cases of human hantavirus infections in Central America.

Adolescent↗
PubMed2004

Virus-specific RNA and antibody from convalescent-phase SARS patients discharged from hospital.

Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus (SARS-CoV). In a longitudinal cross-sectional study, we determined the prevalence of virus in bodily excretions and time of seroconversion in discharged patients with SARS. Conjunctival, throat, stool, and urine specimens were collected weekly from 64 patients and tested for SARS-CoV RNA by real-time polymerase chain reaction; serum samples were collected weekly and tested for SARS-CoV antibody with indirect enzyme immunoassay and immunofluorescence assay. In total, 126 conjunctival, 124 throat swab, 116 stool, and 124 urine specimens were analyzed. Five patients had positive stool samples, collected in weeks 5-9. Two patients seroconverted in weeks 7 and 8; the others were seropositive at the first serum sample collection. In this study, 5 (7.8%) of 64 patients continued to shed viral RNA in stool samples only, for up to week 8 of illness. Most seroconversions occurred by week 6 of illness.

Adolescent↗
PubMed2003

Rift Valley fever epidemic in Saudi Arabia: epidemiological, clinical, and laboratory characteristics.

This cohort descriptive study summarizes the epidemiological, clinical, and laboratory characteristics of the Rift Valley fever (RVF) epidemic that occurred in Saudi Arabia from 26 August 2000 through 22 September 2001. A total of 886 cases were reported. Of 834 reported cases for which laboratory results were available, 81.9% were laboratory confirmed, of which 51.1% were positive for only RVF immunoglobulin M, 35.7% were positive for only RVF antigen, and 13.2% were positive for both. The mean age (+/- standard deviation) was 46.9+/-19.4 years, and the ratio of male to female patients was 4:1. Clinical and laboratory features included fever (92.6% of patients), nausea (59.4%), vomiting (52.6%), abdominal pain (38.0%), diarrhea (22.1%), jaundice (18.1%), neurological manifestations (17.1%), hemorrhagic manifestations (7.1%), vision loss or scotomas (1.5%), elevated liver enzyme levels (98%), elevated lactate dehydrogenase level (60.2%), thrombocytopenia (38.4%), leukopenia (39.7%), renal impairment or failure (27.8%), elevated creatine kinase level (27.3%), and severe anemia (15.1%). The mortality rate was 13.9%. Bleeding, neurological manifestations, and jaundice were independently associated with a high mortality rate. Patients with leukopenia had significantly a lower mortality rate than did those with a normal or high leukocyte count (2.3% vs. 27.9%; odds ratio, 0.09; 95% confidence interval, 0.01-0.63).

Adolescent↗
PubMed2002

Hantavirus pulmonary syndrome--United States: updated recommendations for risk reduction. Centers for Disease Control and Prevention.

This report provides updated recommendations for prevention and control of hantavirus infections associated with rodents in the United States. It supersedes the previous report (CDC. Hantavirus infection--southwestern United States: interim recommendations for risk reduction. MMWR 1993; 42[No. RR-11]: 1-13). These recommendations are based on principles of rodent and infection control, and accumulating evidence that most infections result from exposure, in closed spaces, to active infestations of infected rodents. The recommendations contain updated specific measures and precautions for limiting household, recreational, and occupational exposure to rodents, eliminating rodent infestations, rodent-proofing human dwellings, cleaning up rodent-contaminated areas and dead rodents, and working in homes of persons with confirmed hantavirus infection or buildings with heavy rodent infestations.

Animals↗
PubMed2002

Hantavirus pulmonary syndrome: the new American hemorrhagic fever.

The recognition of hantavirus pulmonary syndrome (HPS) after the investigation of a cluster of unexplained respiratory deaths in the southwestern United States during the spring of 1993 showcased our ability to recognize new and emerging diseases, given the correct juxtaposition of a new clinical entity with circumscribed epidemiologic features that are analyzed with novel diagnostic methods. In less than a decade, HPS has become established as a pan-American zoonosis due to numerous viruses maintained by sigmodontine rodents with rodent- and virus-specific epidemiologic profiles. The classical features of the syndrome-acute febrile illness associated with prominent cardiorespiratory compromise after direct contact or inhalation of aerosolized rodent excreta-has been extended to include clinical variants, including disease with frank hemorrhage, that have confirmed that this syndrome is a viral hemorrhagic fever. Efforts are under way to refine prevention strategies, to understand the pathogenesis of the shock, and to identify therapeutic modalities.

Animals↗
PubMed2002

Threat of a biological terrorist attack on the US food supply: the CDC perspective.

Deliberate contamination of food with biological agents has already been perpetrated in the USA. The US food supply is increasingly characterised by centralised production and wide distribution of products. Deliberate contamination of a commercial food product could cause an outbreak of disease, with many illnesses dispersed over wide geographical areas. Dependent on the biological agent and contaminated food, such an outbreak could either present as a slow, diffuse, and initially unremarkable increase in sporadic cases, or as an explosive epidemic suddenly producing many illnesses. Preparedness for a bioterrorist event affecting the food supply, therefore, entails augmentation of the traditional public-health infrastructure to enhance disease surveillance, accelerate capacity of laboratory detection, rapidly investigate and control outbreaks, and develop capacity for response to mass-casualty disasters.

Bioterrorism↗
PubMed2002

Experimental evaluation of rodent exclusion methods to reduce hantavirus transmission to residents in a Native American community in New Mexico.

We conducted a pilot study to evaluate the efficacy of rodent proofing continuously occupied homes as a method for lowering the risk for hantavirus pulmonary syndrome (HPS) among residents of a Native American community in northwestern New Mexico. Rodent proofing of dwellings was paired with culturally appropriate health education. Seventy homes were randomly assigned to treatment or control categories. Treatment homes were rodent-proofed by sealing openings around foundations, doors, roofs, and pipes and repairing screens and windows. Repairs to each dwelling were limited to $500 US. After repairs were completed, 15-20 snap traps were placed in each treatment and control home and checked approximately every 2 days for an average of 3-4 weeks. During 23,373 trap nights, one house mouse (Mus musculus) was captured in one treatment home, and 20 mice (16 deer mice, Peromyscus maniculatus, two Pinyon mice, Peromyscus truei, and two unidentified mice) were captured in five control homes (one house had 14 captures, two had two captures, and two had one capture). Trap success was 0.01% in treatment homes and 0.15% in controls. Intensity of infestation (mean number of mice captured per infested home) was 1 in treatment homes and 4 in controls. Observations of evidence of infestation (feces, nesting material, gnaw marks, or reports of infestation by occupant) per 100 days of observation were 1.2 in treatment homes and 3.1 in controls. Statistical power of the experiment was limited because it coincided with a period of low rodent abundance (August-November 2000). Nevertheless, these results suggest that inexpensive rodent proofing of occupied rural homes can decrease the frequency and intensity of rodent intrusion, thereby reducing the risk of HPS among rural residents in the southwestern United States.

Animals↗
PubMed2002

An outbreak of Rift Valley fever in Northeastern Kenya, 1997-98.

In December 1997, 170 hemorrhagic fever-associated deaths were reported in Garissa District, Kenya. Laboratory testing identified evidence of acute Rift Valley fever virus (RVFV). Of the 171 persons enrolled in a cross-sectional study, 31(18%) were anti-RVFV immunoglobulin (Ig) M positive. An age-adjusted IgM antibody prevalence of 14% was estimated for the district. We estimate approximately 27,500 infections occurred in Garissa District, making this the largest recorded outbreak of RVFV in East Africa. In multivariable analysis, contact with sheep body fluids and sheltering livestock in one s home were significantly associated with infection. Direct contact with animals, particularly contact with sheep body fluids, was the most important modifiable risk factor for RVFV infection. Public education during epizootics may reduce human illness and deaths associated with future outbreaks.

Adolescent↗
PubMed2002

Hemorrhagic fever with renal syndrome presenting with hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis--which is associated with a variety of infections, malignant neoplasms, autoimmune diseases, and immunodeficiencies--is an uncommon syndrome with a rapidly fatal outcome. We describe the first case of hemorrhagic fever with renal syndrome due to Hantaan virus presenting with reactive hemophagocytosis.

Diagnosis, Differential↗
PubMed2002

Inhalational anthrax outbreak among postal workers, Washington, D.C., 2001.

In October 2001, four cases of inhalational anthrax occurred in workers in a Washington, D.C., mail facility that processed envelopes containing Bacillus anthracis spores. We reviewed the envelopes' paths and obtained exposure histories and nasal swab cultures from postal workers. Environmental sampling was performed. A sample of employees was assessed for antibody concentrations to B. anthracis protective antigen. Case-patients worked on nonoverlapping shifts throughout the facility, suggesting multiple aerosolization events. Environmental sampling showed diffuse contamination of the facility. Potential workplace exposures were similar for the case-patients and the sample of workers. All nasal swab cultures and serum antibody tests were negative. Available tools could not identify subgroups of employees at higher risk for exposure or disease. Prophylaxis was necessary for all employees. To protect postal workers against bioterrorism, measures to reduce the risk of occupational exposure are necessary.

Adult↗
PubMed2002

Opening a bacillus anthracis-containing envelope, Capitol Hill, Washington, D.C.: the public health response.

On October 15, 2001, a U.S. Senate staff member opened an envelope containing Bacillus anthracis spores. Chemoprophylaxis was promptly initiated and nasal swabs obtained for all persons in the immediate area. An epidemiologic investigation was conducted to define exposure areas and identify persons who should receive prolonged chemoprophylaxis, based on their exposure risk. Persons immediately exposed to B. anthracis spores were interviewed; records were reviewed to identify additional persons in this area. Persons with positive nasal swabs had repeat swabs and serial serologic evaluation to measure antibodies to B. anthracis protective antigen (anti-PA). A total of 625 persons were identified as requiring prolonged chemoprophylaxis; 28 had positive nasal swabs. Repeat nasal swabs were negative at 7 days; none had developed anti-PA antibodies by 42 days after exposure. Early nasal swab testing is a useful epidemiologic tool to assess risk of exposure to aerosolized B. anthracis. Early, wide chemoprophylaxis may have averted an outbreak of anthrax in this population.

Anthrax↗
PubMed2002

Genetic analysis of viruses associated with emergence of Rift Valley fever in Saudi Arabia and Yemen, 2000-01.

The first confirmed Rift Valley fever outbreak outside Africa was reported in September 2000, in the Arabian Peninsula. As of February 2001, a total of 884 hospitalized patients were identified in Saudi Arabia, with 124 deaths. In Yemen, 1,087 cases were estimated to have occurred, with 121 deaths. Laboratory diagnosis of Rift Valley fever virus (RVFV) infections included virus genetic detection and characterization of clinical specimens by reverse transcription-polymerase chain reaction, in addition to serologic tests and virus isolation. Genetic analysis of selected regions of virus S, M, and L RNA genome segments indicated little genetic variation among the viruses associated with disease. The Saudi Arabia and Yemen viruses were almost identical to those associated with earlier RVF epidemics in East Africa. Analysis of S, M, and L RNA genome segment sequence differences showed similar phylogenetic relationships among these viruses, indicating that genetic reassortment did not play an important role in the emergence of this virus in the Arabian Peninsula. These results are consistent with the recent introduction of RVFV into the Arabian Peninsula from East Africa.

Antigens, Viral↗
PubMedDate not supplied

Epidemiologic clues to bioterrorism.

Public health investigators have successfully carried out epidemiologic investigations of outbreaks of disease for many years. By far the majority of these outbreaks have occurred naturally. With the recent illnesses resulting from deliberate dissemination of B. anthracis on an unsuspecting population, public health investigation of diseases must now include consideration of bioterrorism as a potential cause of outbreaks of disease. The features of naturally occurring outbreaks have a certain amount of predictability in terms of consistency with previous occurrences, or at least biological plausibility. However, with a deliberately introduced outbreak or infection among a population, this predictability is minimized. In this paper, the authors propose some epidemiologic clues that highlight features of outbreaks that may be suggestive of bioterrorism. They also describe briefly the general process of involvement of agencies at various levels of government, public health and non-public health, depending on the extent of an outbreak or level of suspicion.

Anthrax↗