Kuwait University, Medical college, Microbiology Department

Emerging infection in Kuwait: Cryptosporidiosis

Ammar Abdullah Sadeq (211224229)

Course name: Medical Parasitology (0520-509)

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Introduction:

An emerging infection comes to attention because it involves a newly recognized

organism, a known organism that newly started to cause disease, or an organism whose

transmission has increased. Although Cryptosporidium is not new, evidence suggests that it is

newly spread (in increasingly used day-care centers and possibly in widely distributed water

supplies, public pools, and institutions such as hospitals and extended-care facilities for the

elderly); it is newly able to cause potentially life-threatening disease in the growing number of

immunocompromised patients; and in humans, it is newly recognized, largely since 1982 with the

AIDS epidemic. Cryptosporidium is a most highly infectious enteric pathogen, and because it is

resistant to chlorine, small and difficult to filter, and ubiquitous in many animals, it has become a

major threat to the U.S. water supply. (1) The first case of human cryptosporidiosis was identified

in 1976. In 1993 the largest waterborne cryptosporidiosis outbreak occurred in Milwaukee, USA

and 403,000 people became infected and 104 died (MacKenzie et al,1994).

Cryptosporidium is a microscopic parasite that causes the diarrheal disease

cryptosporidiosis. Both the parasite and the disease are commonly known as "Crypto." (2) The

parasite lives in soil, food and water. It may also be on surfaces that have been contaminated with

waste. Most people with crypto get better with no treatment, but crypto can cause serious

problems in people with weak immune systems such as in people with HIV/AIDS (3). The

parasite is found in the small intestine of many vertebrates, including man. Symptoms and clinical

manifestations include Diarrhea (profuse watery, yellowish – green with offensive odor), Fever (<

30 C°), Vomiting, Nausea, Weight loss, Abdominal pain, Weakness. (4) Body system other than

gastrointestinal tract like respiratory tract may be affected leading to shortness of breath, cough,

wheezing and sinusitis. There are five common species of cryptosporidium which include C.

hominis, C. parvum, C. felis, and C. canis. Of these C. hominis and C. parvum are the two most

common species causing diarrheal disease. Transmission can be waterborne, food borne, zoonotic

(animal to man) and anthroponotic (man to man). Zoonotic transmission is usually by fecal-oral

route and anthroponotic is usually by sharing public recreational areas like swimming pool. C.

hominis is transmitted anthroponotically, C. parvum from Cattle to Man, and C. meleagridis is

transmitted from birds to Man. (4)

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Life cycle and pathophisiology:

Sporulated oocysts, containing 4 sporozoites, are excreted by the infected host through feces and

possibly other routes such as respiratory secretions . Transmission of Cryptosporidium parvum

and C. hominis occurs mainly through contact with contaminated water (e.g., drinking or

recreational water). Occasionally food sources, such as chicken salad, may serve as vehicles for

transmission. Many outbreaks in the United States have occurred in waterparks, community

swimming pools, and day care centers. Zoonotic and anthroponotic transmission of C. parvum

and anthroponotic transmission of C. hominis occur through exposure to infected animals or

exposure to water contaminated by feces of infected animals . Following ingestion (and possibly

inhalation) by a suitable host , excystation occurs. The sporozoites are released and parasitize

epithelial cells ( , ) of the gastrointestinal tract or other tissues such as the respiratory tract. In

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these cells, the parasites undergo asexual multiplication (schizogony or merogony) ( , , ) and

then sexual multiplication (gametogony) producing microgamonts (male) and macrogamonts

(female) . Upon fertilization of the macrogamonts by the microgametes ( ), oocysts ( , )

develop that sporulate in the infected host. Two different types of oocysts are produced, the thick-

walled, which is commonly excreted from the host , and the thin-walled oocyst , which is

primarily involved in autoinfection. Oocysts are infective upon excretion, thus permitting direct

and immediate fecal-oral transmission. (2)

Invasion of host cells leads to loss of the surface epithelium and displacement of the

microvillous border, leading to alteration in villous architecture, with villous atrophy, blunting,

and crypt-cell hyperplasia, and mononuclear cell infiltration in the lamina propria. The causative

mechanisms for the diarrhoea are not fully understood: the large-volume, watery stool resembles

secretory diarrhoea, which may indicate an enterotoxin as a specific mechanism, but a

Cryptosporidium toxin has not been isolated. Increased intercellular permeability and

inflammation in the lamina propria could contribute to secretory diarrhoea via cytokines and

neuropeptides. Crypt-cell hyperplasia causes increased chloride secretion, and villous blunting

leads to decreased sodium absorption, also resulting in overall enhanced secretion. Faecal

leukocytes are usually absent, although infection has been associated with a persistent systemic

inflammatory response. In HIV-infected patients, histopathology shows evidence of mucosal

injury and a variable inflammatory response that is often associated with co-infection with other

pathogens. (5)

Diagnosis:

Diagnosis of cryptosporidiosis is made by examination of stool samples. Because

detection of Cryptosporidium can be difficult, patients may be asked to submit several stool

samples over several days. Most often, stool specimens are examined microscopically using

different techniques (e.g., acid-fast staining, direct fluorescent antibody [DFA], and/or enzyme

immunoassays for detection of Cryptosporidium sp. antigens). Molecular methods (e.g.,

polymerase chain reaction – PCR) are increasingly used in reference diagnostic labs, since they

can be used to identify Cryptosporidium spp. at the species level. Tests for Cryptosporidium are

not routinely done in most laboratories; therefore, health care providers should specifically

request testing for this parasite. (2)

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Fig 1:

Fig 2:

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Fig 3:

Fig 4:

Epidemiology:

In developing countries 8-19% of diarrheal diseases can be attributed to Cryptosporiudium

and is mainly waterborne transmission with most cases related to C. hominis 6 whereas

transmission in developed countries is 1-3% and is usually associated with contact with other

cases, travel abroad and contact with cattles. Species in developed countries (UK and US as two

examples of developed countries) are mixed with C. parvum, C. hominis, C. meleagridis, C. felis,

C. canis, Cryptosporidium cervine, horse, skunk genotypes in UK and in US C. hominis & C.

parvum are prevalent. In Kuwait both anthroponotic and zoonotic transmission is prevalent with

C. parvum and C. hominis as common species.

Fig 5: Geography of worldwide occurrence of human cryptosporidiosis outbreaks and sporadic

cases. A color-coded distribution of the main cases of cryptosporidosis reported in the literature

during the last decade (1998–2008) for the entire population (adults and children) is here

represented. Waterborne and foodborne diseases are represented by red and grey color,

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respectively. Spreading of the infection due to HIV immunological impairment is represented by

green and travel-related disease by pink color. When not applicable the definition of waterborne

and foodborne disease, the term community disease has been applied to person-to-person contacts

and represented by a pale blue color. For countries characterized by two or three coexisting

transmission modes, a double color-filling effect plus thick border lines have been used,

consistently with the above reported code. (7)

Fig 6: Geographic distribution of Cryptosporidium parvum. Worldwide distribution in temperate and tropical zone (8)

Cryptosporidium and cryptosporidiosis distribution in the Middle East and Gulf Countries:

Iran: Three Cryptosporidium species, C. hominis, C. parvum, and C. meleagridis, were

recognized, and zoonotically transmitted C. parvum was the predominant species found in

humans. (Meamer, A.R et all, 2007)9

Yemen: Cryptosporidium sp was identified from children sample of different age group (1

month – 12 yrs). The overall positive percentage was 43.7%. The higher incidence (36.2 %) was

occurred in males while the lowest incidence (32.7 %) was observed in females (r= 0.876; P=

0.001). The correlation between infected cases and the type of drinking water was r = 0.121.

Among the cases examined by ELISA (92 cases), 26.1 % were infected. The correlation between

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seropositivity and gender was r= 0.652 (P=0.031). Therefore, Cryptosporidium spp. is a

significant pathogen among children at Taiz. Fresh water supplies, education, eating habits and

domestic animals are considered the main sources for transmission of cryptosporidiosis. (Al-

Shamiri et al, 2010)10

Egypt: Research showed an elevated prevalence of C. hominis (80.0%), the most anthroponotic

species, suggesting a human-human transmission. Also 40% of samples were infected with C.

parvum. (Abd El Kader NM et al, 2012)11

Iraq: Cryptosporidium among 114 positive cases with intestinal parasites was 18.3%. The boy-

to-girl ratio was 1:2 among the Cryptosporidium-positive children. Most patients complained of

abdominal colic and watery diarrhoea and were clinically dehydrated. The associated symptoms

were fever and vomiting. Cryptosporidium and Giardia appeared to be associated. (Mahdi et al,

1996)12

Jordan: Genotyping of 44 Cryptosporidium isolates from Jordanian children at the 18S rRNA

locus and a unique diagnostic locus identified four Cryptosporidium species; C. parvum (22), C.

hominis (20), C. meleagridis (1) and C. canis (1). Sub-genotype analysis of 29 isolates at the 60-

kDa glycoprotein (GP60) locus identified three C. parvum, two C. hominis subtype families and

one C. meleagridis subtype. Several rare and novel subtypes were identified indicating unique

endemicity and transmission of Cryptosporidium in Jordan. (Hijjawi et al, 2010)13

Saudi Arabia: Between the March and May of 2000, stool specimens were collected from

children aged <5 in six pre-school crèches and clinics in the Jeddah area of Saudi Arabia. Sixty-

three (25%) of the children had diarrhoeal disease but the other 190 were asymptomatic. When

the stool samples were stained and examined for the oocysts of Cryptosporidium spp. and other

enteric protozoa, 20 (32%) of the symptomatic children but only nine (4.7%) of the asymptomatic

were found to be excreting Cryptosporidium oocysts. Similarly, Cyclospora cayetanensis was

found, always as a co-infection with Cryptosporidium sp., in seven (11%) of the children with

diarrhoeal disease but only eight (4.2%) of the asymptomatics. One asymptomatic child was

found to be co-infected with Isospora belli and Cryptosporidium. Giardia intestinalis and cysts of

Entamoeba histolytica/dispar were detected in 18 (29%) and nine (14%) of the children with

diarrhoeal disease and in eight (4.2%) and 13 (6.8%) of the asymptomatic children, respectively.

(Al-Braiken FA et al, 2003)14

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Kuwait:

Research was done on the prevalence of cryptosporidium in children in Kuwait. The

median age of infected children was 4.5 years, and 77% of infections occurred during the cool

season of November to April. Fifty-eight of the children (94%) had Cryptosporidium parvum,

three (5%) had Cryptosporidium hominis, and one (1%) had both C. parvum and C. hominis.

Altogether, 13 subtypes of C. parvum (belonging to four subtype allele families) and C. hominis

(belonging to three subtype allele families) were observed, with 92% of specimens belonging to

the common allele family IIa and the unusual allele family IId. Thus, the transmission of

cryptosporidiosis in Kuwaiti children differed significantly from other tropical countries. (Iqbal et

al, 2005)15

Cryptosporidiosis in Kuwaiti children: seasonality and endemicity:

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Fig 7: Seasonal distribution of Cryptosporidium genotypes and subtypes in Kuwaiti children. Black bars, C. parvum; hatched bars, C. hominis.

Cryptosporidium oocysts were detected in 51 (10%) children with diarrhea. Prevalence

was highest (73%) in children > 2 years of age compared with children < 2 years of age. The

maximum number of cases, 38 of 51 (75%), was seen during the months January to April,

indicating a marked seasonal variation. Polyparasitism was common in children with diarrhea;

however, 43 of the 51 (84%) children with cryptosporidiosis had cryptosporidium infection only.

Blastocystis hominis and Endolimax nana were the most common parasites detected (38% and

15%, respectively). Forty-seven of the 51 (90%) children with cryptosporidiosis were Kuwaiti

and gave no history of travel abroad, suggesting that the infection was acquired indigenously.

Sociodemographic information on children with cryptosporidiosis suggests three possible modes

of transmission of infection: drinking contaminated water stored in overhead water tanks, person

to person, or contact with infected animals. (Iqbal et al, 2001)16

Cryptosporidiosis in Kuwaiti children: association of clinical characteristics with Cryptosporidium species and subtypes:

Associated clinical manifestations varied between C. parvum and C. hominis. Diarrhea

associated with subtype Id, the most commonly identified C. hominis subtype, was more severe

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than that associated with other subtypes. The study showed predominance of C. parvum IIa and

IId among the Kuwaiti children with diarrhea. In addition, subtype Id of C. hominis was

associated with more diverse and severe clinical manifestations in infected children suggesting

that parasite genetics may play an important role in the clinical manifestations of human

cryptosporidiosis. (Iqbal et al, 2011)17

Comparison of Cryptosporidiosis in Kuwait and other countries:

Tropical countries have shown highest prevalence of cryptosporidiosis in children younger

than 2 years whereas Kuwaiti children infected were significantly older. The same thing was also

found in Saudi Arabia. The delayed infection in Kuwaiti children is attributed to better hygiene.

Also in tropical countries, Cryptosporidium transmission in children is usually associated with the

rainy season and water borne transmission is the major route in the epidemiology of

cryptosporidiosis in these areas. In Kuwait, due to very little rainfall transmission is usually

during November to April (see fig 7 above). Waterborne transmission is less likely due to

desalinated water as source of drinking water in Kuwait. Differences in infection source could be

an important factor for the unique endemicity in Kuwait. C. hominis is more common in most

other countries but C. parvum is more common in Kuwait. Predominance of C. parvum may be

related to zoonotic transmission but all C. parvum infections are not due to zoonotic transmission.

Due to low proportions of C. hominis anthroponotic transmission is not as important as in other

countries. (Iqbal et al, 2005)15

References:

1. Guerrant, R.L. (1997) Cryptosporidiosis: An Emerging, Highly Infectious Threat. EID Journal, Vol 3, No 1, pp. 51-57http://wwwnc.cdc.gov/eid/article/3/1/97-0106_article.htm

2. CDC. (2011) Parasites - Cryptosporidium (also known as "Crypto")http://www.cdc.gov/parasites/crypto/

3. Medline Plus. (2012) Cryptosporidiosishttp://www.nlm.nih.gov/medlineplus/cryptosporidiosis.html

4. Baha Latif. Cryptosporidiosis Food & Water Borne Parasitic Disease http://jknkelantan.moh.gov.my/v3/uploads/files/pdfs/khc2011/OP_08.pdf

5. BMJ. (2011) http://bestpractice.bmj.com/best-practice/monograph/1149/basics/pathophysiology.html

6. Snelling et al. (2007) Cryptosporidiosis in developing countries. J Infect Developing Countries, 1(3): 242-256.

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http://jidc.org/index.php/journal/article/viewFile/19734601/2087. Putignani et al. (2010) Global Distribution, Public Health and Clinical Impact of the

Protozoan Pathogen Cryptosporidium. Interdisciplinary Perspectives on Infectious Diseases, Volume 2010 (2010), Article ID 753512, 39 pages, doi:10.1155/2010/753512http://www.hindawi.com/journals/ipid/2010/753512/

8. The Korean society for Parasitology: Web Atlas of Medical Parasitology. (2003) Cryptosporidium parvumhttp://atlas.or.kr/atlas/alphabet_view.php?my_codeName=Cryptosporidium%20parvum

9. Meamer, A.R et al. (2007) Molecular Characterization of Cryptosporidium Isolates from Humans and Animals in Iran. Appl. Environ. Microbiol, Vol 73, No 3, pp. 1033-1035 http://aem.asm.org/content/73/3/1033.full.pdf

10. Al-Shamiri et al. (2010) The Prevalence of Cryptosporidium spp. in Children, Taiz District, Yemen. Iranian J Parasitol : Vol. 5 , No. 2 , pp. 26- 32 http://journals.tums.ac.ir/upload_files/pdf/_/15795.pdf

11. Abd El Kader NM et al. (2012) Detection of Cryptosporidium parvum and Cryptosporidium hominis in human patients in Cairo, Egypt. Parasitol Res. 2012 Jan; 110(1):161-6. Epub 2011 May 24http://www.ncbi.nlm.nih.gov/pubmed/21607688

12. Mahdi et al. (1996) First report of cryptosporidiosis among Iraqi children. Eastern Mediterranean Health Journal, Volume 2, Issue 1, 1996, Page 115-120http://www.emro.who.int/publications/emhj/0201/16.htm

13. Hijjawi et al. (2010) Identification of rare and novel Cryptosporidium GP60 subtypes in human isolates from Jordan. Experimental Parasitology 125 (2010) 161–164http://ipac.kacst.edu.sa/eDoc/2010/190275_1.pdf

14. Al-Braiken FA et al. (2003) Detection of Cryptosporidium amongst diarrhoeic and asymptomatic children in Jeddah, Saudi Arabia. Ann Trop Med Parasitol; 97(5): 505-10 http://www.ncbi.nlm.nih.gov/pubmed/12930614

15. Iqbal et al. (2005) Unique Endemicity of Cryptosporidiosis in Children in Kuwait. Journal of Clinical Microbiology, Vol 43, No 6, pp. 2805-2809

16. Iqbal et al. (2001) Cryptosporidiosis in Kuwaiti children: seasonality and endemicity. Clin Microbiol Infect. 7(5):261-6

17. Iqbal et al. Cryptosporidiosis in Kuwaiti children: association of clinical characteristics with Cryptosporidium species and subtypes. J Med Microbiol May 2011 vol. 60 no. 5 647-652

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