Cholera, Diarrhoea, Other plant diseases
Details: Cholera outbreak in Nampula
An outbreak of cholera was reported in Nampula in northern Mozambique on 04 March 2014. The health authorities already recorded 172 cases by the time of the information release and mentioned that an average of 10 to 13 severely affected people still arrive at the cholera treatment centre every day. To control the outbreak, water samples were analysed to determine the presence and level of contamination and the residents were encouraged by mobile health units to apply and strengthen individual and collective hygiene measures. In addition, the city authorities were requested to implement sanitation procedures to prevent the spread the disease.
Characteristics of the illness
Epidemiology: Cholera is an illness characterized by a severe diarrhoea that can kill within hours if not treated. According to the World Health Organization (WHO) about 3–5 million cholera cases occur every year and 100 000–120 000 of the infected people die. The disease is endemic to many countries and occurs especially in places where hygienic conditions are poor.
Cause: The causative agent is Vibrio cholerae, a bacterium that belongs to the family Vibrionaceae. It is a Gram-negative, facultative anaerobic and non-spore-forming curved rod. Based on differences in the sugar composition of the heat-stable surface somatic “O” antigen, different serogroups can be distinguished. The O1 and O139 serogroups are responsible for the disease outbreaks, with O1 being the most spread agent. In the human body, Vibria cholerae releases a cholera toxin in the intestine provoking thereby the acute diarrhoea.
Transmission: Cholera is contracted by consuming food or water contaminated with discharges of infected people containing Vibrio cholerae. Areas with poor hygienic conditions such peri-urban slums and refugee camps where minimum requirements of clean water and sanitation are not met. Cholera is rarely spread directly from human to human.
Symptoms: These occur within 2 hours to five days after infection and are characterized by e.g. a purging diarrhoea, vomiting, stomach cramps and weakness. The acute diarrhoea and vomiting are responsible for an extreme dehydration and an increase of the concentration of blood cells. Many infected people do not exhibit symptoms.
Diagnosis: This includes, patient examination and questioning, analysis of stool for isolation and identification of Vibrio cholerae (mainly serogroup O1 or O139) by culture on specific media, biochemical tests (Crystal VC® dipstick kit) and DNA investigation.
Treatment: Many people are successfully treated through administration of oral rehydration salts. However, severely affected individuals require administration of intravenous fluids and antibiotics such as tetracycline chloramphenicol, doxycycline and Erythromycin.
Prevention: The critical factor in reducing the impact of cholera is the provision of safer water and sanitation. Education of the population in the application of good hygienic life styles and safe food handling is also very important. In addition, there are 2 types of oral cholera vaccines that can be administrated to prevent and control the illness.
The occurrence of more aggressive new strains of Vibrio cholerae in Asia and Africa raises a serious global public health concern. The WHO also reported a continuing increase in cholera cases every year, including 589 854 cases from 58 countries, including 7816 deaths in 2011. Another big issue is the occurrence of multi-drug resistant strains of Vibrio cholerae (6 emerged in Bangladesh recently), which compromises more the chances for successful treatment in severely affected people
Birmingham, M.E., Lee, L.A., Ndayimirije, N., Nkurikiye, S., Hersh, B.S., Wells, J.G., Deming, M.S. (1997). Epidemic cholera in Burundi: patterns of trans- mission in the Great Rift Valley Lame region. Lancet, 349 (9057), 981–985.
The World Health Organization (2013). Cholera 2012. Weekly epidemiological record, 88(31), 321-336.