Temporal and spatial dynamics of Cryptosporidium parvum infection on dairy farms in the New York City Watershed: a cluster analysis based on crude and Bayesian risk estimates

<p>Abstract</p> <p>Background</p> <p><it>Cryptosporidium parvum </it>is one of the most important biological contaminants in drinking water that produces life threatening infection in people with compromised immune systems. Dairy calves are thought to be the primary source of <it>C. parvum </it>contamination in watersheds. Understanding the spatial and temporal variation in the risk of <it>C. parvum </it>infection in dairy cattle is essential for designing cost-effective watershed management strategies to protect drinking water sources. Crude and Bayesian seasonal risk estimates for <it>Cryptosporidium </it>in dairy calves were used to investigate the spatio-temporal dynamics of <it>C. parvum </it>infection on dairy farms in the New York City watershed.</p> <p>Results</p> <p>Both global (Global Moran's I) and specific (SaTScan) cluster analysis methods revealed a significant (p < 0.05) elliptical spatial cluster in the winter with a relative risk of 5.8, but not in other seasons. There was a two-fold increase in the risk of <it>C. parvum </it>infection in all herds in the summer (p = 0.002), compared to the rest of the year. Bayesian estimates did not show significant spatial autocorrelation in any season.</p> <p>Conclusions</p> <p>Although we were not able to identify seasonal clusters using Bayesian approach, crude estimates highlighted both temporal and spatial clusters of <it>C. parvum </it>infection in dairy herds in a major watershed. We recommend that further studies focus on the factors that may lead to the presence of <it>C. parvum </it>clusters within the watershed, so that monitoring and prevention practices such as stream monitoring, riparian buffers, fencing and manure management can be prioritized and improved, to protect drinking water supplies and public health.</p

Session presentation

Aflatoxins are a group of toxic metabolites produced by Aspergillus molds that contaminate a variety of food and animal feeds. Exposure to aflatoxins causes serious illness in humans, including liver cancer and stunting in children. When cows ingest aflatoxin-contaminated feed, they secrete aflatoxin M1 (AFM1) in their milk. Aflatoxin M1 has been detected in high concentration throughout sub-Saharan Africa in cow’s milk and in human breast milk, putting infants at high risk. In Ethiopia, a currently ongoing study has revealed high levels of contamination of dairy feeds with aflatoxins in the Greater Addis milk shed. In this study, we have collected raw milk samples from dairy farmers and milk collectors in the Greater Addis milk shed and quantified the levels of AFM1 using enzyme-linked immunosorbent assay (ELISA). Using a cross-sectional study design, a total of 100 raw milk samples were collected from dairy farms in Addis Ababa and its surrounding areas (27 from Addis Ababa, 23 from Debre Zeit, 9 from Sebeta, 31 from Sendafa and 10 from Sululta). All the milk samples were contaminated with AFM1 and most (92%) of the samples had aflatoxin levels exceeding 50 ppt, which is the FAO/WHO and EU permissible level of AFM1 in milk. The highest AFM1 content was 4977 ppt and the lowest was 28 ppt. In addition, ten raw milk samples were collected from milk collectors located in Addis Ababa (1), Debre Zeit (3) and Sululta (6). All of the samples from milk collectors were contaminated with AFM1 exceeding 50 ppt. The high levels of AFM1 in milk in the Greater Addis milk shed is alarming, because it is one of the largest milk sheds in the country, and most residents of Addis Ababa get their milk from these sources. Children in particular are encouraged to drink milk as much as possible. Considering that young children are weaned on to cow's milk and they are not immune-competent at this early age, consumption of milk contaminated with AFM1 may further suppress their immunity and also contribute to stunting. In addition, it has been estimated that aflatoxins may play a causative role in up to 30% of the cases of liver cancer globally each year. Therefore, the high level of aflatoxin contamination in the peri-urban dairy value chain of Addis Ababa requires urgent response to reduce human and animal exposure to these toxins. Our research group is currently testing intervention strategies to address the problem of aflatoxins in dairy feed in Ethiopia

The need for awareness raising on the causes and treatment of mastitis in livestock among pastoralists in southern Ethiopia

Ethiopia has high prevalence of clinical and subclinical mastitis in different livestock species and production systems and these contribute substantially to poor productivity in affected herds. Thus far, studies have focused on identification of microbial pathogens and associated risk factors for mastitis. However, relatively little is known about the knowledge and beliefs of livestock keepers regarding prevailing livestock health problems in general and mastitis in particular. An accurate understanding of these beliefs would be central to the design of effective disease control programs that give due consideration to the livestock keepers. As a first step, we set out to conduct a qualitative study aimed at exploring the knowledge and belief surrounding the causes, clinical signs and treatments for mastitis in (agro-) pastoral communities in southern Ethiopia. In four village administrations of Yabello district of Borana zone, different participatory tools were used to collect qualitative data. Individual interviews were held with 40 women using a pre-tested semi-structured questionnaire guide. Four focus group discussions with women were also carried out (one in each village) and informal discussion were held with different community members. The data was analysed qualitative by repeated reading to identify different themes. Mastitis is locally known as ‘dhukkuba muchaa”, which translates to ‘disease of teats’. Those interviewed classified mastitis into three types: (1) tick infestation (dirandisa), (2) swelling of udder often with pus discharge (nyaqarsa) and (3) acute mastitis caused by ‘evil eye’ (buda) associated with bloody milk. Tick infestation was perceived to directly cause mechanical damage to udder tissue or to result in swelling leading to nyaqarsa. Our analysis also revealed a strong perception that acute mastitis is caused by 'evil eye'; generally affected cows are with large udders mostly during late pregnancy and early lactation. The pastoralists often treat mastitis by combining both modern and traditional methods. Hand removal and acarcide application were the preferred methods for limiting tick infestation while swelling and ‘evil eye’ cases were treated with antibiotics (e.g. oxytetracycline). The study also revealed that specific herbs, only known by the herbalists, were used for traditional treatment of mastitis and although this information could not be divulged at the time, it should form the subject of further investigation. Traditional treatment for evil eye was often administered through nostrils, raising questions about its effectiveness. It is interesting that the pastoralists associated mastitis to tick infestation which is compatible with existing scientific evidence. However, the misperception of causes for acute mastitis as ‘evil eye’ can be problematic as far as the application of appropriate treatment and management of the disease is concerned and highlights the need for capacity building on causes of mastitis and how they can be treated