Sunday, January 21, 2007

Protozoal infections

In a setting such as Brunei jungle where sanitation system are often poor & many unknown sources of water from lakes and river, contaminated water sources are often the source that eventually lead to outbreaks if there is any. As such, all water-borne protozoa are emphasized and described in greater details.

1.6 Entamoeba Histolytica (Amoebiasis)

Brief overview

Entamoeba histolytica is a common parasite in the large intestine of humans. It is often present in 3 stages: the active ameba, the inactive cyst or the intermediate precyst. Entamoeba histolytica can cause amoebiasis which is usually contracted by ingesting water or food contaminated by amoebic cysts. This is usually a waterborne disease. It also can be transmitted by direct contact with dirty hands .

Mode of transmission
• Ingestion of cyst transmitted by fecal oral route in contaminated food and water.

Associated symptoms :
Symptoms are usually gastrointestinal such as diarrhea, vomiting, abdominal pain or discomfort and fever. Dysentry (bloody stool) is often observed in people infected with entamoeba histolytica. Amebic liver abscess with symptoms such as right upper quandrant pain, weight loss, fever, tender & enlarged liver. Symptoms take from a few days to a few weeks to develop and manifest themselves (Usually 2- 4 wks). Most infected patients are asymptomatic. Most infection occur in the digestive tract but other tissues may be invaded. Complications include ulcerative and abscess pain.

Treatment / Prevention


Infection with Entamoeba histolytica occurs in both the intestine and/or the liver. Asymptomatic amebiasis can be treated with iodoquinol, furamide or paromomycin. Paromomycin is the most effective drug for treating intestinal infection. Metronidazole is the drug of choice to destroy the amebae that invaded tissues. Both types of drug must be given to treat infection, with metronidazole usually being given first followed by paromomycin.

Prevention or control measures consist of improving environmental and food sanitation as cysts are usually ingested through contaminated water. In the tropics, contaminated food and vegetables are also important cyst sources. As such, avoid contamination of food and water and promote good personal hygiene such as hand washing regularly. Use of purification tablets to purify water supply especially in tropics zone is also essential and lastly, always cook vegetable or any food fully before consumption.

1.7 Sporozoa- Plasomodium sp (Malaria parasite)

There are four species of plasmodia namely plasmodium vivax, plasmodium ovale, plasmodium malariae and plasmodium flaciparum. Mode of transmission to humans is by the bloodsucking bite of female anopheles mosquito of various species. Malaria today is generally limited to the tropic and subtropics area. The life cycle of malaria parasite include sporozites, merozoites, erythrocytic development and sporogony.

Clinical features:
Most common associated clinical features include high fever, nausea, vomiting & headaches, anaemia (pale-looking like face due to destruction of red blood cells).

Treatment
Chloroquine (Aralen) is the drug of choice for treatment of all susceptible forms of malaria during the acute attack. In the case of resistant to chloroquine, mefloquine is now the chemoprophylatic drug of choice to be administered to patient. Primaquine eliminates the exoerythrocytic forms in the liver. Malaria coma from chloroquine-resistant falciparum malaria should be treated with parental quinine or quinidine plus intravenous doxycycline or clindamycin. Oral therapy should replace parental treatment as soon as possible.

Prevention / Control

Anti-malarial drug such as maloprim or primaquine can be given to man before they venture into any tropics area such as the jungle or forest. Personal protection against mosquitoes can be enhanced by clothing with love sleeves and trousers or even usage or repellents.

1.8 Flagellate – Giardia lamblia

Giardia lamblia is the only common pathogenic protozoan found in the duodenum and jejunum of humans. Similarly to entamoeba histolytica, mode of transmission is through the ingestion of cyst in fecally contaminated food and water or by direct fecal contamination. Cysts can survive in water for up to 3 months. In poor sanitiation areas such as jungle, outbreaks that are associated with giardia is not surprising since poor hygiene practices are commonly present in tropic area settings.

Clinical features :

Nonbloody, foul smelling diarrhea, nausea, anorexia, flatulence & abdominal cramps.

Treatment

Metronidazole will clear over 90% of G lamblia infections. Oral quinacrine hydrochloride (Atabrine) and furazolidone (Furoxone) are alternatives.

Prevention

It can be prevented by drinking boiled, filtered, iodine treated water in areas with poor sanitiation system or unreliable source of water.

1.9 Sporozoa – Toxoplasma

Brief Overview
Diseases caused by Toxoplasma gondii are known as toxoplasmosis. It is usually transmitted by ingestion of cysts in uncooked meat or food contaminated with cat feces. Since it is primarily transmitted through food sources, it was shortlisted since uncooked or not fully cooked food is very likely to present in an area without proper cooking tools or gases.

Treatment
Acute infection can be treated with a combination of pyrimethamine and sulfadiazine or trisulfapyrimidines. Alternative drugs include spiramycin, clindamycin, trimethoprim-sulfamethoxazole and various other sulfonamide drugs.

1.10 Helminths- Wuchereria bancrofti

Brief overview
Wuchereria bancrofti is a parasitic filarial worm that causes lymphatic filariasis, which is the inflammation and obstruction of lymphatic glands, sometimes resulting in elephantiasis if left untreated. It is suspected as the disease is found primarily in Africa, South America, and other tropical and sub-tropical countries.

Mode of transmission
The disease spreads from person to person by mosquito bites. When a mosquito bites a person who has lymphatic filariasis, microscopic worms circulating in the person's blood enter and infect the mosquito. People get lymphatic filariasis from the bite of the infected mosquito.

Associated symptoms :
Symptoms include swelling and impaired circulation. The lymphatic system becomes dysfunctional as it becomes hardened and clogged with fibrous tissue. Without the proper drainage of fluids, the affected tissue will expand and elephantiasis can occur as a result.

Treatment / Prevention
Either ivermectin, albendazole, or diethylcarbamazine is used to treat the infection. Unfortunately, much of the tissue damage may not be reversible. The medication is started at low doses to prevent reactions caused by large numbers of dying parasites.

*Summary

In summary, unknown sources of water either from lakes or river that could harbour parasites such as Giardia lamblia or Entamoeba Histolytica that may unknowingly causes disease in soldiers after drinking those contaminated water which may seem clear in color at one glance. Environment settings of jungle where there could be many mosquitoes could contribute to infection such as malaria by P. Vivax, P.Malariae, P.falciparum & P.ovale as well as lymphatic filariasis by Wuchereria bancrofti.

References

1. Geo. F. Brooks, Janet S. Butel, Stephen A. Morse. (2001). Medical
Microbiology. Singapore.McGraw-Hill.
2.www.wikipedia.org

2 comments:

Samantha said...

Hi! We've got a question for you. Is malaria infection really prominent in Brunei? We've found from this site http://www.state.gov/r/pa/ei/bgn/2700.htm that malaria has already been eradicated.

This question has been discussed by the group (blank 06)

Unknown said...

My wife is allergic to flagyl, and we can't find quinacrine anywhere. She took it 12 years ago for giardia, and now needs it again. I read some studies that bacitracin tablets are effective, but I find only ointments.

Does anybody know a source? I can get a prescription sent anywhere.