Cryptosporidiosis: History, definition, outbreak

Cryptosporidiosis
The protozoan Cryptosporidium parvum was first described in 1907 in asymmetric mice, and for decades now it has been known to be a pathogen of at least 40 mammals and varying numbers of reptiles and birds.

Although the first documented human case was not recorded until 1976, this disease has a worldwide prevalence of 1-4% among patients with diarrhea, and it appears to be increasing.

It is estimated to cause infections in from 7 to 38% of AIDS patients in some hospitals.

The prevalence of C. parvum is diarrheal stools is similar to that of Giardia lamblia.

In human disease is self limiting in immunocompetent individuals, but it is a serious infection in the immunocompromised, such as AIDS patients.

The protozoan is known to be present in at least some bodies of water and this exist the potential for food transmission.

The fecal-oral route of transmission is the most important, but indirect transmission by food and milk is known occur.

C. parvum is an obligate intracellular coccidian parasite that carries out its life cycle in one host. Following ingestion of the thick-walled oocystsm, they excyst in the small intestine and free sporozoites and penetrate the microvillous region of host enterocytes, where sexual reproduction leads to the development of zygotes.

They invade host cells by disrupting their own membrane as well as that of their host.

Host cell acting polymerization at the interface between the parasite and the host cell cytoplasm has been found to be necessary for infection.

The first demonstrated waterborne outbreak of cryptosporidiosis occurred in Braun Station, Texas, in 1984 following the consumption of artesian well water.

There were actually two outbreaks – one in May and the other in July, with 79 victims. A second outbreaks with 13,000 victims occurred in Carrolton, Georgia in 1987 and oocysts were found in the tools of 58 of 147 victims.

The clinical course of cryptosporidiosis in human depends on the immune state, with the most severe cases occurring in the immunocompromised.

In immunocompetent individuals, the organism primarily parasitizes the intestinal epithelium and causes diarrhea.

The disease is it self-limiting, with an incubation period of 6-14 days and symptoms typically last 9-23 days.

In the immunocompromised diarrhea is profuse and watery with as many as 71 stools per day and up to 171 per day reported.

Diarrhea is sometimes accompanied by mucus but rarely blood.
Cryptosporidiosis: History, definition, outbreak

Vibrio vulnificus

Vibrio vulnificus naturally inhabits warm estuarine environments and can infect humans via wound exposure or seafood consumption. These infections are rare and generally limited to individuals with preexisting chronicle illnesses of the immunocompromised.

Vibrio vulnificus is a significant cause of seafood related morbidity and mortality in the United States. On the coast of the Gulf of Mexico, numbers of Vibrio vulnificus are highest with water temperature around 26 ° C and salinity levels of 5-25 parts pr thousands. Under these conditions , number of Vibrio vulnificus can greater than 100000/g of oyster meat.

Vibrio vulnificus can invade through the intestinal barrier onto the bloodstream and has the highest case, fatality rate (approx. 50%) among foodborne pathogens.

Conclusive evidence that Vibrio vulnificus is associated with two forms of serious human illness was presented in 1979 when a study of 39 patients from whom clinical specimens were collected over the period 1964 b-1977 was published.

Beginning in the early 1970s, reports began appearing of extra-intestinal infections with such symptoms as hemorrhagic rash, fever, shock, and tissue ederma and necrosis at the site of the infection. Surgical debridement of affected tissue, amputation of limbs and death were common outcomes.
Vibrio vulnificus 

Immunocompromised

Immunocompromised patient is at increased risk for infection due to defective defense mechanisms.

Recent data suggest that 0.25% to 1.5% of the total population in the United States may be immunocompromised.

As population change new concerns arise about food safety. The number of elderly and immunocompromised persons is rising.

Immunocompromised persons form a group at increased risk of foodborne illnesses. Susceptible individuals typically became ill form smaller doses of pathogens, and the symptoms and durations of their illness can be much more even life threatening.

People infected with human immunodeficiency virus, are at risk of acquiring foodborne illness not only through commonly recognized pathogens, but also through pathogens that may be frequently ingested but do not normally cause illness in healthy persons.
Immunocompromised

Food Borne illnesses

Food Borne illnesses
Since food is biological in nature and is capable of supplying consumers with nutrition, it is equally capable of supporting the growth of contaminating microorganisms. Two types of bacterial food borne disease are recognized: intoxications and infections.

Food borne bacterial intoxication is caused by the ingestion of food containing preformed bacterial toxin resulting from bacterial growth in food.

Food borne infection, on the other hand, is caused by the ingestion of food containing viable bacteria which then grow and establish themselves in host, resulting in illness. Some pathogens occur in normal, healthy animals and in some instances man. Certain microorganisms are thus ubiquitous in nature, occurring on soil and vegetation, in animal wastes, and on animal carcasses. Human skin surfaces and nasal passages harbor staphylococci. Water supply may contain pathogens when contaminated with fecal mater.

Coastal waters in particularly may also naturally harbor recognized as pathogen Vibrio vulnificus. It is thus obvious how difficult to prevent one or more pathogens from entering raw foods.

The most common symptoms associated with food borne illness is diarrhea. Depending on the pathogenicity of the organisms and the susceptibility or health status of the host, the illness may be acute and self-limiting, or it may lead to other serious chronic and life threatening sequellae. Food borne illnesses are more likely to be life-threatening for the immune compromised, the aged , and those individuals debilitated by underlying health problems such as cirrhosis, hepatitis, hemachromatosis. The increase number of sporadic outbreaks of hemorrhagic colitis and the sequella hemolytic uremic syndrome has caused health officials to speculate that Escherichia coli serotypes may be the source of many diarrheal disease of unknown etiology. Food borne disease however, may not necessarily manifest itself in diarrheal illness but may illicit other symptoms such as abdominal cramps or pseudo appendicitis. Although a number of unusual outbreaks related to processed foods have occurred on the past few years , the majority of food borne illnesses are attributable to improper handling , cooking , and syirage practices on food service operations pr in the home.
Food Borne illnesses