TRAINING COURSE ON MALARIA ELIMINATION FOR THE GMSChiang Mai, Thailand, 10-21 August 2015

Risintha PremaratneMBBS, MPH (Bio-security), MSc, MD (Community Medicine)Director, NMCP, Ministry of Health, Sri Lanka

Prevention of re-introduction of

Malaria

Explain the concepts of receptivity, vulnerability, and their relationship to the likelihood of malaria becoming re-established

Define vigilance and describe patterns of vigilance required to prevent re-establishment of transmission in different settings

Explain the required capabilities and organization of the health services in countries that have recently been freed from malaria transmission

Determine training needs for adequate malaria vigilance in different settings

Learning objectivesBy the end of this Unit, the participant should be able to:

Malaria programme phases and milestones on the path to malaria elimination

The vectorial capacity, which is or would be found in a given area at a given point in time in the absence of deliberate control measures. It is mainly determined by the interaction between local vectors and ecology including factors of human ecology such as outside night-time activities, type of housing, use of mosquito nets etc.

Receptivity

Number of new infections the population of a given vector would distribute per case per day at a given place and time, assuming conditions of non-immunity. Factors affecting vectorial capacity include: (i) the density of female anophelines relative to humans; (ii) their longevity, frequency of feeding and propensity to

bite humans; and (iii) the length of the extrinsic cycle of the parasite.

Vectorial capacity

The risk of imported human or mosquito malaria parasite carriers being present in a given area at a given point in time. For humans, those carriers who stay long in the area and those who are asymptomatic are the most important. Infected vectors may enter by flying across land borders or by air transport (airport malaria).

Vulnerability

Vulnerability

Related to the importation by humans The roles of the two main groups are different

local people going abroad incoming immigrants

Related to the importation by vectors: 2 types of vector importation

importation of infected vectors importation of alien vectors previously not present in

the given area

Vector control coverage

Vectorial capacity

Indigenous cases

Imported cases

Years

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Slide courtesy of Allan Schapira

An indication may be derived from its malaria history: original degree of endemicity; vectorial capacity before the implementation of

intensive control measures; response of vector to withdrawal of insecticide

spraying after the application of intensive control measures;

environmental changes as a result of developments, which may affect the vector population.

Degree of receptivity of an area

A. culicifacies density -2013

An indication of the degree of vulnerability will be available from knowledge of traditional patterns of travel into the area recent changes that will be apparent from the

epidemiological investigation of cases in the recent past.

The number of people arriving, their origin, the categories of people involved as well as their local destination and length of stay

Degree of vulnerability of an area

http://au.news.yahoo.com/thewest/a/-/breaking/16053899/sri-lanka-rescues-138-stranded-on-sinking-boat/

Singapore – Kunming Rail Link

Trans Asian Highway

Trans Asian Railway

Slide courtesy of Deyer Gopinath

The receptivity and vulnerability of the area are poorly correlated since receptivity characterizes the possibility and conditions for re-establishment of malaria transmission in the country after its elimination, whereas vulnerability characterizes the risk of introduction of malaria parasites into an area where they do not exist

Assessment of the risk of malaria re-introduction

Scenario Receptivity Vulnerability Level of the risk of malaria re-establishment

1 + + From high to low depending on the severity of risk factors

2 + - None (can rise with increasing degree of vulnerability)

3 - + None (can rise with increasing degree of susceptibility)

4 - - None

Vigilance

A function of the public health service during the prevention of re-introduction phase, consisting of alert watchfulness for any occurrence of malaria in an area in which it had not existed or from which it had been eliminated, and the application of necessary measures against it.

probability of malaria becoming re-established varies from area to area

pattern of vigilance appropriate to each area is necessary

Vigilance

early case detection by a vigilant general health service, complemented by

epidemiological investigation of every case and focus and

appropriate curative and preventive measures,- may be sufficient to prevent re-establishment of transmission

Patterns of vigilanceLow levels of receptivity & vulnerability

supplement above activities by active case detection, which may possibly be combined with other regularly repeated health activities involving house visits

Patterns of vigilance Increasing levels of receptivity & vulnerability

Based on continued updating of the information on the local situation it may be necessary to reduce receptivity by the use of appropriate vector control measures

indoor residual spraying long-lasting insecticidal nets or Larviciding IVM

Patterns of vigilance Areas of high vulnerability

Lack of an enabling environment – increasing reluctance to commit personnel, time and

expenditure to a disease not present. The general public and politicians forget about malaria &

its devastating effects The disease is no longer recorded – becomes a

“forgotten” disease result in loss of skills in clinical and microscopy diagnosis

and epidemiological investigation of cases little opportunity for training based on actual cases

Key consequences of being malaria free

Risk of re-introduction is high in areas with high receptivity and vulnerability

Resistance to a continued effort against malaria can be expected both within the health services and among the general population

Thus, a high level technical nucleus where knowledge and skills are maintained must be kept up in the country

Organization of the health service

Key consequences of being malaria free

The nucleus should: consist of the central office of the former malaria control programme

and its specialized technical sections; function in the framework of the directorate of preventive health

services and thereby have free lines of communication with the general health services at central and intermediate levels;

exercise overall oversight of the country’s vigilance activities and case notification, and maintain the national malaria case register;

be responsible for QC & QA of diagnostic laboratory operations as well as the regular updating of the antimalarial drug policy for:

– the management of malaria cases, – chemoprophylaxis for residents travelling to endemic areas;

be responsible for planning and QC of entomological investigations and essential vector control operations directed at reducing the receptivity of an area for malaria.

Example of the organization and operations

Organization of the health service

Maintaining adequate levels of malaria training, which can be guided by the technical nucleus is necessary

all relevant personnel in areas where there is a possibility of re-establishment; the training focuses on the technical aspects related to maintaining the malaria-free status;

all relevant personnel in the public health service; the training raises awareness of factors causing increases in vulnerability and receptivity, so that appropriate measures can be taken to lessen their effects;

the general medical profession and undergraduate medical students; they require continued education in:

– the diagnosis and treatment of malaria, – prevention measures, including those for international travelers.

Training

Maintaining an adequate level of competence in the laboratory diagnosis of malaria. The technical nucleus can

Conduct relevant teaching and training act as the cross-checking centre for blood films (which

can identify personnel who need re-training). An annual malaria report as:

A tool to stimulate and maintain interest a useful educational medium.

Training contd.

Tasks of the programme at a glance

• In relation to the risk of importation of the parasites and vectors (vulnerability):– To reduce the risk of importation of parasite carriers;– To minimize the infective period;– To reduce the risk of importation of infected vectors;– To reduce the risk of importation of new vectors;

• In relation to the risk of local transmission (receptivity):– To maintain vectorial capacity at the lowest, with priority for vulnerable areas;

• In relation to the abilities of the health systems to react (vigilance):– To promptly detect eventual sources of infection;– To ensure that they do not infect local mosquitoes – To maintain good practices of the public and private health services in relation to

malaria cases, through training, dissemination of information, awareness-raising and logistics;

– To maintain capabilities of local health services to react promptly to any outbreak, by adequate training, financing and logistics.

– To influence practices of relevant segments of the public including populations at high risk and other sectors, in relation to malaria, by HE & collaboration.

the occurrence of three or more introduced and/or indigenous malaria infections linked in space and time to local mosquito-borne transmission in the same geographical focus, for 2 consecutive years for P. falciparum for 3 consecutive years for P. vivax

Criteria for the re-establishment of malaria transmission

Reading material for guidelines on prevention of re-introduction and certification of malaria elimination

Malaria elimination: A field manual for low and moderate endemic countries: Chapter 6 (pp.40-44) (http://www.who.int/malaria/publications/atoz/9789241596084/en/)Regional framework for prevention of malaria reintroduction and certification of malaria elimination 2014–2020

Acknowledgement

• Mikhail Ejov for his guidance & numerous slides used in this presentation

• Allan Schapira for the original material used for the presentation

Exercise 6.1

• Each group is required to prepare a short summary (one page) about a specific country experience on prevention of malaria re-introduction or a history of a post-elimination outbreak.