Qutub Syed

Sporadic Cryptosporidiosis Case- Control Study with Genotyping

Risk factors for Cryptosporidiosis in United Kingdom.

Health sequelae of human cryptosporidiosis in immunocompetent patients

BACKGROUND There have been no systematic studies following up the longer term health effects of cases of cryptosporidiosis for which genotype data exist. METHODS We report a follow-up study of cases of laboratory-confirmed cryptosporidiosis. Case patients were sent a postal questionnaire asking about a wide range of symptoms occurring within 2 months after their initial diagnosis, and control subjects were sent the questionnaire 2 months after they had been recruited to the original study. RESULTS Completed questionnaires were received from 235 case patients and 232 control subjects. For 111 of the case patients, the species of the infecting strain was known; 61 of these strains were Cryptosporidium hominis (human genotype), and 50 were Cryptosporidium parvum (bovine genotype). Forty percent of the case patients reported recurrence of intestinal symptoms after resolution of the acute stage of illness, irrespective of whether infection was with C. hominis or C. parvum. Reports of joint pain (odds ratio [OR], 2.8), eye pains (OR, 2.44), recurrent headache (OR, 2.10), dizzy spells (OR, 1.69), and fatigue (OR, 3.0) were significantly more common in case patients than in control subjects, but only in people who had experienced C. hominis infection. Joint symptoms experienced by case patients were of longer duration than those experienced by control subjects. CONCLUSIONS Our results confirm previous reports of a high rate of relapse of gastrointestinal symptoms following recovery from an acute episode of cryptosporidiosis and show that C. hominis but not C. parvum is associated with an increased risk of nonintestinal sequelae. This study demonstrates that the impact of cryptosporidiosis on public health extends beyond that of the acute diarrheal illness and can lead to significant health sequelae.

Outbreak of cryptosporidiosis associated with a disinfected groundwater supply.

In an outbreak of cryptosporidiosis in Warrington, a town in North-West England, 47 cases were recorded between November 1992 and February 1993, most within the first month. There was a strong statistical association between cases and residence in an area supplied from two groundwater sources. In a case-control study, a strong association between having drunk unboiled tap water from these sources, and a dose-response relationship were found. Oocysts were not detected in the water supply. During very heavy rainfall one source of water was found to drain surface water directly from a field containing livestock faeces, thereby bypassing natural sandstone filtration. Exceptionally heavy rainfall occurred at the probable time of infection. After withdrawal of the original water supply, the outbreak rapidly subsided. It was concluded that there was very strong evidence that this outbreak was waterborne. This, the second documented outbreak of cryptosporidiosis attributable to a groundwater supply, demonstrates that infection can be transmitted from a disinfected groundwater source despite apparently satisfactory treated water quality. We recommended that guidelines for protection of groundwater are implemented, raw groundwater should be routinely monitored for microbiological contamination, and the structure of all sources and waterworks should be assessed in risk surveys of water catchment areas.

Identification of potential environmentally adapted Campylobacter jejuni strain, United Kingdom.

In a study of Campylobacter infection in northwestern England, 2003–2006, C. jejuni multilocus sequence type (ST)–45 was associated with early summer onset and was the most prevalent C. jejuni type in surface waters. ST-45 is likely more adapted to survival outside a host, making it a key driver of transmission between livestock, environmental, and human settings.

Campylobacter jejuni multilocus sequence types in humans, northwest England, 2003-2004.

MLST can be used to describe and analyze the epidemiology of campylobacteriosis in distinct human populations.

Self-reported diarrhea in a control group: a strong association with reporting of low-pressure events in tap water.

In a recently conducted case-control study of sporadic cryptosporidiosis, 6.6% of subjects in the control group reported having had diarrhea in the 2 weeks before completion of the questionnaire. In an analysis of this control group, there was a very strong association between self-reported diarrhea and reported low water pressure at the faucet.

Foot and Mouth Disease and Cryptosporidiosis: Possible Interaction between Two Emerging Infectious Diseases

During 2001, a large outbreak of foot and mouth disease occurred in the United Kingdom, during which approximately 2,030 confirmed cases of the disease were reported, >6 million animals were slaughtered, and strict restrictions on access to the countryside were imposed. We report a dramatic decline in the reported incidence of human cryptosporidiosis in northwest England during weeks 13–38 in 2001, compared with the previous 11 years. This decline coincided with the period of foot and mouth restrictions. No similar reduction occurred in the other 26 weeks of the year. We also noted a substantial decline in the proportion of human infections caused by the bovine strain (genotype 2) of Cryptosporidium parvum during weeks 13–38 that year but not during the other weeks.

A case-control study of lifestyle risk factors associated with tuberculosis in Liverpool, North-West England

The aim of this study was to identify the subtle influences of exposure and individual lifestyles on the risk of developing tuberculosis. A retrospective case-control study (with matching by sex, age, postcode and ethnicity) of all tuberculosis cases notified over a 7-yr period in Liverpool, UK, was carried out. Multiple logistic regression showed that, before diagnosis, cases were 7.4 times more likely to have had visitors from abroad; 4.0 times more likely to have been born abroad; and 3.8 times more likely to have lived with someone with tuberculosis. Subtle socioeconomic factors were also evident with cases 4.0 times less likely to have additional bathrooms. Lifestyle factors emerged with cases 2.3 times more likely to have smoked for at least 30 yrs, 3.8 times less likely to eat dairy products every week and 2.6 times less likely to have had high blood pressure. At interview, these factors were still evident, but cases, unlike controls, had reduced their smoking and alcohol consumption and were less likely to go out of the home or exercise than before their illness. Within individuals, lifestyle consequences of tuberculosis lead to a “healthier” lifestyle on the one hand (less smoking and alcohol consumption), but a reduced quality of life (social activity) on the other.

Re-emerging syphilis: a detrended correspondence analysis of the behaviour of HIV positive and negative gay men

BackgroundRecent syphilis outbreaks in the UK have raised serious concerns about the sexual health of the population. Moreover, syphilis appears more likely to facilitate HIV transmission than any other sexually transmitted infection (STI).MethodsThe sexual and other risk behaviour of a sample of HIV positive and negative gay men with and without syphilis was subjected to a detrended correspondence analysis (DCA).ResultsA DCA plot was used to illustrate similarity of individuals in terms of their behaviours, regardless of their infection status. The majority of those with syphilis (78%; 18/23) fell into a high-risk group with more partners, and use of anonymous sex venues and drugs during sex. However, 16% of uninfected controls (8/49) and 62% of HIV positive individuals without syphilis (8/13) also fell into this high-risk group.ConclusionsUsing a statistical technique that is novel for this type of investigation, we demonstrate behavioural overlaps between syphilis-infected individuals in an ongoing UK outbreak and uninfected HIV positive and negative controls. Given the high-risk behaviour of a significant proportion of uninfected individuals, ongoing transmission of syphilis and HIV in this population seems likely.

Investigation of Food and Environmental Exposures Relating to the Epidemiology of Campylobacter coli in Humans in Northwest England

ABSTRACT This study uses multilocus sequence typing (MLST) to investigate the epidemiology of Campylobacter coli in a continuous study of a population in Northwest England. All cases of Campylobacter identified in four Local Authorities (government administrative boundaries) between 2003 and 2006 were identified to species level and then typed, using MLST. Epidemiological information was collected for each of these cases, including food and recreational exposure variables, and the epidemiologies of C. jejuni and C. coli were compared using case-case methodology. Samples of surface water thought to represent possible points of exposure to the populations under study were also sampled, and campylobacters were typed with multilocus sequence typing. Patients with C. coli were more likely to be older and female than patients with C. jejuni. In logistic regression, C. coli infection was positively associated with patients eating undercooked eggs, eating out, and reporting problems with their water supply prior to illness. C. coli was less associated with consuming pork products. Most of the cases of C. coli yielded sequence types described elsewhere in both livestock and poultry, but several new sequence types were also identified in human cases and water samples. There was no overlap between types identified in humans and surface waters, and genetic analysis suggested three distinct clades but with several “intermediate” types from water that were convergent with the human clade. There is little evidence to suggest that epidemiological differences between human cases of C. coli and C. jejuni are a result of different food or behavioral exposures alone.