Wim van der Hoek

Reducing acute poisoning in developing countries—options for restricting the availability of pesticides

Hundreds of thousands of people are dying around the world each year from the effects of the use, or misuse, of pesticides. This paper reviews the different options to reduce availability of the most hazardous chemicals, focusing on issues in developing countries. Emphasis is placed on the fatal poisoning cases and hence the focus on self-harm cases. Overall, it is argued here that restricting access to the most hazardous pesticides would be of paramount importance to reduce the number of severe acute poisoning cases and case-fatalities and would provide greater opportunities for preventive programmes to act effectively. The aim should be to achieve an almost immediate phasing out of the WHO Classes I and II pesticides through national policies and enforcement. These short-term aims will have to be supported by medium- and long-term objectives focusing on the substitution of pesticides with safe and cost-effective alternatives, possibly guided by the establishment of a Minimum Pesticide List, and the development of future agricultural practices where pesticide usage is reduced to an absolute minimum. Underlying factors that make individuals at risk for self-harm include domestic problems, alcohol or drug addiction, emotional distress, depression, physical illness, social isolation or financial hardship. These should be addressed through preventive health programmes and community development efforts.

The 2007-2010 Q fever epidemic in The Netherlands: characteristics of notified acute Q fever patients and the association with dairy goat farming.

We describe the Q fever epidemic in the Netherlands with emphasis on the epidemiological characteristics of acute Q fever patients and the association with veterinary factors. Data from 3264 notifications for acute Q fever in the period from 2007 through 2009 were analysed. The patients most affected were men, smokers and persons aged 40–60 years. Pneumonia was the most common clinical presentation (62% in 2007 and 2008). Only 3.2% of the patients were working in the agriculture sector and 0.5% in the meat-processing industry including abattoirs. Dairy goat farms with Coxiella burnetii-induced abortion waves were mainly located in the same area where human cases occurred. Airborne transmission of contaminated dust particles from commercial dairy goat farms in densely populated areas has probably caused this epidemic. In 2010, there was a sharp decline in the number of notified cases following the implementation of control measures on dairy goat and sheep farms such as vaccination, hygiene measures and culling of pregnant animals on infected farms. In combination with a rise in the human population with antibodies against C. burnetii, these have most likely ended the outbreak. Development of chronic Q fever in infected patients remains an important problem for years to come.

The use of a geographic information system to identify a dairy goat farm as the most likely source of an urban Q-fever outbreak

BackgroundA Q-fever outbreak occurred in an urban area in the south of the Netherlands in May 2008. The distribution and timing of cases suggested a common source. We studied the spatial relationship between the residence locations of human cases and nearby small ruminant farms, of which one dairy goat farm had experienced abortions due to Q-fever since mid April 2008. A generic geographic information system (GIS) was used to develop a method for source detection in the still evolving major epidemic of Q-fever in the Netherlands.MethodsAll notified Q-fever cases in the area were interviewed. Postal codes of cases and of small ruminant farms (size >40 animals) located within 5 kilometres of the cluster area were geo-referenced as point locations in a GIS-model. For each farm, attack rates and relative risks were calculated for 5 concentric zones adding 1 kilometre at a time, using the 5-10 kilometres zone as reference. These data were linked to the results of veterinary investigations.ResultsPersons living within 2 kilometres of an affected dairy goat farm (>400 animals) had a much higher risk for Q-fever than those living more than 5 kilometres away (Relative risk 31.1 [95% CI 16.4-59.1]).ConclusionsThe study supported the hypothesis that a single dairy goat farm was the source of the human outbreak. GIS-based attack rate analysis is a promising tool for source detection in outbreaks of human Q-fever.

Mortality Attributable to 9 Common Infections: Significant Effect of Influenza A, Respiratory Syncytial Virus, Influenza B, Norovirus, and Parainfluenza in Elderly Persons

BACKGROUND Because there may be substantial hidden mortality caused by common seasonal pathogens, we estimated the number of deaths in elderly persons attributable to viruses and bacteria for which robust weekly laboratory surveillance data were available. METHODS On weekly time series (1999-2007) we used regression models to associate total death counts in individuals aged 65-74, 75-84, and ≥85 years (a population of 2.5 million) with pathogen circulation-influenza A (season-specific), influenza B, respiratory syncytial virus (RSV), parainfluenza, enterovirus, rotavirus, norovirus, Campylobacter, and Salmonella-adjusted for extreme outdoor temperatures. RESULTS Influenza A and RSV were significantly (P < .05) associated with mortality in all studied age groups; influenza B and parainfluenza were additionally associated in those aged ≥75 years, and norovirus was additionally associated in those aged ≥85 years. The proportions of deaths attributable to seasonal viruses were 6.8% (≥85 years), 4.4% (75-84 years), and 1.4% (65-74 years), but with great variations between years. Influenza occasionally showed lower impact than some of the other viruses. CONCLUSIONS The number of different pathogens associated with mortality in the older population increases with increasing age. Besides influenza A and RSV, influenza B, parainfluenza and norovirus may also contribute substantially to elderly mortality.

Risk factors for acute pesticide poisoning in Sri Lanka

This report describes the characteristics of patients with acute pesticide poisoning in a rural area of Sri Lanka and, for intentional self‐poisoning cases, explores the relative importance of the different determinants. Data were collected for 239 acute pesticide‐poisoning cases, which were admitted to two rural hospitals in Sri Lanka. Sociodemographic characteristics, negative life events and agricultural practices of the intentional self‐poisoning cases were compared with a control group. Most cases occurred among young adults and the large majority (84%) was because of intentional self‐poisoning. Case fatality was 18% with extremely high case fatality for poisoning with the insecticide endosulfan and the herbicide paraquat. Cases were generally younger than controls, of lower educational status and were more often unemployed. No agricultural risk factors were found but a family history of pesticide poisoning and having ended an emotional relationship in the past year was clearly associated with intentional self‐poisoning. The presence of mental disorders could only be assessed for a subsample of the cases and controls and this showed that alcohol dependence was a risk factor. This study shows that acute pesticide poisoning in Sri Lanka is determined by a combination of sociodemographic and psychological factors. Suggestions are given for interventions that could control the morbidity and mortality due to acute pesticide poisoning in developing countries.

STRONG ASSOCIATION BETWEEN HOUSE CHARACTERISTICS AND MALARIA VECTORS IN SRI LANKA

The objective of this study was to determine whether house characteristics could be used to further refine the residual insecticide-spraying program in Sri Lanka. Indoor-resting mosquito densities were estimated in 473 houses based on fortnightly collections over a two-and-a-half-year period. The type of house construction and the exact location of all houses were determined. In a multivariate analysis, distance of less than 750 meters between a house and the main vector-breeding site was strongly associated with the presence of Anopheles culicifacies in the house (odds ratio [OR] 4.8, 95% confidence interval [CI] 3.4-6.8) and to a lesser extent with the presence of An. subpictus (OR 1.4, 95% CI 1.1-1.7). Poor housing construction also was an independent risk factor (OR for An. culicifacies 1.3, 95% CI 1.0-1.9; OR for An. subpictus 1.3, 95% CI 1.0-1.6). It is recommended that a malaria control strategy focus on residential areas within 750 meters of streams and rivers, with special attention given to areas with the poorest type of house construction.

Coxiella burnetii infection among blood donors during the 2009 Q-fever outbreak in The Netherlands.

BACKGROUND: In 2007, 2008, and 2009 outbreaks of Q‐fever occurred in the Netherlands with increasing magnitude. The 2009 outbreak with 2354 reported cases is the largest human Q‐fever outbreak ever recorded. To assess the extent of infection and the safety of donated blood, we tested local blood donations for presence of Coxiella burnetii antibodies and DNA.

Follow-up of 686 patients with acute Q fever and detection of chronic infection

BACKGROUND Recent outbreaks in the Netherlands allowed for laboratory follow-up of a large series of patients with acute Q fever and for evaluation of test algorithms to detect chronic Q fever, a condition with considerable morbidity and mortality. METHODS For 686 patients with acute Q fever, IgG antibodies to Coxiella burnetii were determined using an immunofluorescence assay at 3, 6, and 12 months of follow-up. Polymerase chain reaction (PCR) was performed after 12 months and on earlier serum samples with an IgG phase I antibody titer ≥ 1:1024. RESULTS In 43% of patients, the IgG phase II antibody titers remained high (≥ 1:1024) at 3, 6, and 12 months of follow-up. Three months after acute Q fever, 14% of the patients had an IgG phase I titer ≥ 1:1024, which became negative later in 81%. IgG phase I antibody titers were rarely higher than phase II titers. Eleven cases of chronic Q fever were identified on the basis of serological profile, PCR results, and clinical presentation. Six of these patients were known to have clinical risk factors at the time of acute Q fever. In a comparison of various serological algorithms, IgG phase I titer ≥ 1:1024 at 6 months had the most favorable sensitivity and positive predictive value for the detection of chronic Q fever. CONCLUSIONS The wide variation of serological and PCR results during the follow-up of acute Q fever implies that the diagnosis of chronic Q fever, necessitating long-term antibiotic treatment, must be based primarily on clinical grounds. Different serological follow-up strategies are needed for patients with and without known risk factors for chronic Q fever.

Q fever in The Netherlands: the role of local environmental conditions

The Netherlands is facing a Q fever epidemic in which dairy goats are implicated. People living close to an affected farm have an increased risk. However, no human cases were reported around a number of farms with serious Q fever problems. To assess the role of local environmental conditions which may add to the transmission or risk of Q fever, we gathered datasets on vegetation, land use, soil characteristics, and weather conditions in 5 km areas around infected farms. Areas without transmission had a higher vegetation density and relatively shallow groundwater conditions. Vegetation and soil moisture are relevant factors in the transmission of Coxiella burnetii from infected farms to humans, by reducing the amount of dust available for dispersion of the bacteria. The findings suggest that intensive goat and sheep husbandry should be avoided in areas that are characterized by a combination of arable land with deep groundwater and little vegetation.

Irrigation water as a source of drinking water: is safe use possible?

BACKGROUND In arid and semi‐arid countries there are often large areas where groundwater is brackish and where people have to obtain water from irrigation canals for all uses, including domestic ones. An alternative to drawing drinking water directly from irrigation canals or village water reservoirs is to use the water that has seeped from the irrigation canals and irrigated fields and that has formed a small layer of fresh water on top of the brackish groundwater. The objective of this study was to assess whether use of irrigation seepage water for drinking results in less diarrhoea than direct use of irrigation water and how irrigation water management would impact on health.